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lavacuator tube image gastric lavage

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Lavacuator Tube

The Lavacuator (also spelled "lavacuator") is a large-bore, clear plastic orogastric hose specifically designed for gastric lavage. It is the preferred tube for stomach washout in cases of poisoning and overdose.

Images

Image A & B - Classic Lavacuator tube (double-lumen design):

Lavacuator tube - classic double-lumen orogastric hose

(A) The assembled tube. (B) Components labeled: 1 = gastric hose with multiple distal holes, 2 = drainage tubing, 3 = Y-connector adapter for closed-system lavage.

Modern lavacuator / large-bore gastric lavage tube (green-striped variant):

Modern large-bore gastric lavage tube with green stripe

Key Features

Feature	Detail
Bore size (adults)	36-40 Fr (external diameter ~12-13.3 mm)
Bore size (children)	24-28 Fr (diameter ~7.8-9.3 mm)
Route	Orogastric (NOT nasogastric - too large for the nose)
Distal end	Multiple holes cut near the tip to enhance aspiration of particulate matter
Y-connector	Closed system with two arms - one for fluid infusion, one for drainage
Material	Clear, flexible plastic (allows visual inspection of aspirate)

How It Works

The Y-connector closed system allows sequential lavage cycles:

Clamp the drainage arm, infuse aliquots of fluid (tap water in adults; warmed normal saline in children) into the stomach
Clamp the infusion arm, open the drainage arm - gravity drainage of stomach contents
Intermittent suction can be applied to enhance emptying

Clinical Notes

Larger diameter tubes are more likely to retrieve particulate matter, but whole pills still rarely pass through
The tube is large enough that it must be passed orally only
Position patient in left lateral decubitus, Trendelenburg (~20-degree tilt) to reduce aspiration risk and slow passage of gastric contents into the duodenum
Confirm placement radiographically before starting lavage

Sources: Roberts and Hedges' Clinical Procedures in Emergency Medicine, Ch. 42; P.C. Dikshit Textbook of Forensic Medicine and Toxicology

Absolute vs relative

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Absolute vs Relative Contraindications to Gastric Lavage

The textbooks group contraindications into hard stops (absolute) and situations requiring caution (relative):

Absolute Contraindications

#	Contraindication	Reason
1	Unprotected airway (no gag reflex, obtunded patient without ETT)	High risk of aspiration of lavage fluid and gastric contents
2	Corrosive ingestion (strong acids or alkalis)	Passing the tube risks further esophageal/gastric perforation
3	Hydrocarbon ingestion (unless containing highly toxic pesticides or heavy metals)	Risk of aspiration pneumonitis; the toxin absorption risk is less than the lavage risk
4	Known esophageal stricture	Tube passage risks rupture
5	History of gastric bypass surgery	Altered anatomy - tube placement is dangerous and unreliable

Relative Contraindications (Use With Caution)

#	Contraindication	Reason
1	Combative / uncooperative patient	Risk of injury to patient and staff; tube displacement
2	Bleeding diathesis (coagulopathy, thrombocytopenia)	Mucosal trauma during tube passage can cause significant bleeding
3	Ingestion >1-2 hours prior	Most benefit is within 1 hour; risk-benefit tilts against lavage with increasing time

Important Note on "Protected Airway"

A patient who is intubated moves the airway contraindication from absolute to relative - many clinicians will proceed with lavage in a seriously ill intubated patient because the airway is already protected. However, intubation + paralysis solely to perform gastric lavage is generally not recommended.

Key principle: The distinction between absolute and relative is essentially - absolute contraindications mean lavage should never be done regardless of circumstance; relative means the risk must be weighed against the potential benefit of toxin removal, with additional precautions taken.

Source: Roberts and Hedges' Clinical Procedures in Emergency Medicine, Ch. 42 - Gastric Lavage

Why hypothermia contraindicated in hypothermia

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Why is Cold Gastric Lavage Contraindicated in Hypothermia?

The question is: cold gastric lavage (used as a cooling technique) is contraindicated in patients who are already hypothermic (low body temperature). This seems paradoxical because cold lavage is used to cool patients -- so why not in hypothermia?

The Logic

Cold gastric lavage is a core cooling technique designed for hyperthermia (heatstroke) -- it works by instilling iced water into the stomach, which sits adjacent to the liver, great vessels, kidneys, and heart, rapidly drawing heat away from core organs.

If a patient is already hypothermic (core temp already low), instilling iced water would:

Worsen the hypothermia - further drop core temperature, potentially into life-threatening ranges (severe hypothermia <28°C causes ventricular fibrillation)
Remove what little heat remains - the body in hypothermia is already struggling to maintain core temperature; cold lavage actively strips more heat from central organs
Trigger cardiac arrhythmias - the heart in hypothermia is highly irritable; cold fluid near the pericardium/great vessels can precipitate VF

What It Is Used For (and When It Is Appropriate)

Indication	Contraindication
Severe hyperthermia / heatstroke	Pre-existing hypothermia
Cooling rate: ~0.15°C/min	Would deepen dangerous core cooling
Best when external cooling is insufficient	Any condition with low core temp

Key Teaching Point

Cold gastric lavage takes heat away from the core. In hyperthermia you want this. In hypothermia you absolutely do not -- it would be adding insult to injury by cooling an already dangerously cold patient further.

The same principle applies to other cold lavage methods (bladder, peritoneal, rectal) -- all are contraindicated in hypothermia for identical reasons.

Source: Roberts and Hedges' Clinical Procedures in Emergency Medicine, Ch. 65 - Cold Gastric Lavage / Contraindications to Rapid Cooling

Create a quick reference guide on heatstroke vs hypothermia management

Activated charcoal use in gastric lavage

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1. Quick Reference Guide: Heatstroke vs Hypothermia Management

Definition & Classification

Feature	Heatstroke	Hypothermia
Core temp	>40°C (>104°F)	<35°C (<95°F)
Mild	37-40°C	32-35°C
Moderate	--	28-32°C
Severe	>40°C with organ failure	<28°C
Key danger	Multi-organ failure, cerebral edema	VF, cardiac arrest

Heatstroke Management

Goal: Reduce rectal temp to ≤40°C within 30 minutes

Step 1 - ABCs + Monitoring

IV access, cardiac monitor, pulse oximetry
Consider intubation if GCS impaired (also needed before gastric lavage)

Step 2 - Cooling Techniques (in order of preference)

Technique	Method	Cooling Rate	Notes
Evaporative (1st choice)	Tepid water mist (15°C) + large warm fans, expose all body surfaces	~0.10-0.31°C/min	Simplest, fastest external method; non-invasive
Ice water immersion	Full body submersion in ice water	~0.15-0.20°C/min	Effective but cumbersome; monitoring difficult; shivering
Strategic ice packs	Axilla, groin, neck	~0.03-0.11°C/min	Adjunct; patient tolerates poorly
Cold gastric lavage	10 mL/kg iced water, 30-60s dwell, suction - repeat	~0.15°C/min	Requires ETT; invasive; limited human data
Cold peritoneal lavage	Peritoneal catheter, cold fluid	~0.11-0.56°C/min	Rapid; invasive; only if not responding
Hemodialysis/ECMO	Cold dialysate 30-35°C	Variable	Last resort for refractory cases

Step 3 - Pharmacologic Adjuncts

Drug	Indication	Notes
Dantrolene	Muscle rigidity OR suspected malignant hyperthermia (MH)	NOT routinely used in heatstroke (no benefit in RCT)
Bromocriptine / Amantadine	Neuroleptic malignant syndrome (NMS)	Dopamine agonist
IV Ketorolac 30mg	Adjunct to cooling	One RCT: temp 2x lower at 90 min vs placebo
Benzodiazepines	Shivering / agitation	Reduces metabolic heat production

Cooling Contraindication

Rapid cooling is never contraindicated in heatstroke
Cold gastric lavage: contraindicated without protected airway (ETT)

Hypothermia Management

Goal: Increase core temp at 0.5-2.0°C/hour; avoid aggressive rewarming in mild/stable cases

Rewarming Methods by Severity

Severity	Temp	Method
Mild	32-35°C	Passive External Rewarming (PER): remove wet clothing, insulate, blankets, warm oral fluids (only if fully alert), warm IV fluids
Moderate	28-32°C	Active External Rewarming (AER): heating pads/blankets to trunk only, forced warm air; + less invasive active core
Severe	<28°C	Active Core Rewarming (ACR): warmed humidified oxygen, warm IV fluids 40-42°C, bladder/gastric/pleural warm lavage, ECMO/bypass

Active Core Rewarming Options

Technique	Route	Notes
Warmed IV fluids (40-42°C)	IV	Counteracts cold diuresis; first step
Warmed humidified O₂	Airway	40-45°C
Warm bladder lavage	Foley	Minimally invasive
Warm gastric lavage	NG/OG tube	Warm fluid (opposite of heatstroke!)
Warm pleural lavage	Chest tubes	Bilateral
Peritoneal lavage	Peritoneal catheter	Relative CI if prior abdominal surgery
ECMO / Cardiac bypass	Vascular	Most effective; for cardiac arrest + hypothermia

Pitfalls in Hypothermia

⚠️ Danger	Reason
Aggressive rewarming in mild cases	Can cause rebound hypotension, paradoxical core temp drop, arrhythmias
Cold IV fluids	Worsen hypothermia
Cold gastric lavage	Absolutely contraindicated - worsens core cooling, precipitates VF
Ignoring underlying cause	Hypoglycemia, sepsis, adrenal crisis, hypothyroidism, drug OD must be treated simultaneously

Side-by-Side Summary

	Heatstroke	Hypothermia
Core temp direction	↑ Must LOWER	↓ Must RAISE
Gastric lavage fluid	Ice cold	Warm (40-45°C)
Fan/airflow	Yes - maximize evaporation	No - increases heat loss
Dantrolene	Only if rigidity / MH	Not indicated
ECMO	Last resort for refractory	Cardiac arrest + severe hypothermia
Endpoint	Rectal temp ≤40°C in 30 min	Core temp rising 0.5-2°C/hr

Sources: Roberts and Hedges' Clinical Procedures in Emergency Medicine, Ch. 65; Goldman-Cecil Medicine; Tintinalli's Emergency Medicine

2. Activated Charcoal in Gastric Lavage

What Is It?

Activated charcoal (AC) is a fine black powder of carbon treated to have an enormous surface area. It adsorbs (binds) most organic toxins in the gut, reducing systemic absorption. It is given after gastric lavage is completed, through the same lavage tube before removal.

Timing in the Procedure

After gastric aspiration and lavage are completed → administer AC slurry through the gastric tube → then clamp the tube before removal (to avoid dribbling into airway)

Dosing

Age	Single Dose
<1 year	1 g/kg body weight
1-12 years	25-50 g
>12 years / adult	25-100 g

Target ratio: 10:1 (charcoal : toxin by weight) if amount ingested is known. Plain aqueous charcoal (without sorbitol) is preferred.

Indications

Most organic drug/toxin overdoses where a clinically significant fraction remains in the GI tract
Most effective within 60 minutes of ingestion (extended for bezoar-forming drugs like aspirin)
AC is generally considered superior to gastric lavage alone for gut decontamination
MDAC (multiple-dose AC) is used to:
- Prevent ongoing absorption (extended-release/enteric-coated preparations)
- Enhance elimination of already-absorbed drugs by interrupting enterobiliary recirculation (e.g., phenobarbital, theophylline, carbamazepine, digoxin, dapsone, quinine)

Contraindications

Contraindication	Reason
Unprotected airway (no ETT)	Aspiration risk - can cause pneumonitis, ARDS, bronchiolitis obliterans
Corrosive ingestion (acids/alkalis)	No benefit; triggers vomiting; can enter mediastinum/peritoneum if perforation
Aliphatic hydrocarbons	Not adsorbed by AC; increases aspiration risk
Iron ingestion	Iron NOT adsorbed by charcoal
Lithium ingestion	Lithium NOT adsorbed by charcoal
Ethanol ingestion	Not adsorbed
Bowel obstruction/perforation	Inspissated charcoal worsens obstruction
Gastric bypass history	Anatomical risk

Complications

Complication	Notes
Pulmonary aspiration	Most feared; 4-39% in intubated patients; can cause pneumonitis, ARDS
Vomiting	In both awake and obtunded patients
Constipation	Common
Bowel obstruction	From inspissated charcoal (especially MDAC)
Bowel perforation	Rare; reported in diverticular disease
Electrolyte imbalance	With MDAC + cathartic combinations

Lavage + AC vs AC Alone

Within 1 hour of ingestion: lavage + AC provides a small but statistically significant advantage over AC alone
After 1 hour: no difference in outcome between lavage + AC vs AC alone
Current trend: AC used in <1% of overdose cases in the US (2014 data); lavage also declining

Source: Roberts and Hedges' Clinical Procedures in Emergency Medicine, Ch. 42; Goldman-Cecil Medicine, Ch. 96

Urinary alkalization vs urinary acidification

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Urinary Alkalinization vs Urinary Acidification

Both are enhanced elimination techniques that exploit the principle of ion trapping - manipulating urinary pH to keep a drug ionized in the tubular lumen so it cannot be reabsorbed and must be excreted.

The Core Principle: Ion Trapping

Drug type	Behavior in urine	Trick
Weak ACID (e.g. salicylate, phenobarbital)	Unionized in acidic urine → reabsorbed	Alkalinize urine → drug becomes ionized → trapped → excreted
Weak BASE (e.g. amphetamine, PCP)	Unionized in alkaline urine → reabsorbed	Acidify urine → drug becomes ionized → trapped → excreted (but NOT recommended - see below)

1. Urinary Alkalinization ✅ (Recommended)

Mechanism

Raising urine pH causes weak acid drugs to become ionized (negatively charged) → cannot cross tubular cell membranes → stay in urine → excreted. Also alkalinizes serum, which keeps drugs like salicylate out of the CNS (added benefit).

Drugs Treated

Drug	Notes
Salicylates (aspirin)	Primary indication; serum level >30 mg/dL = start; alkalinization also prevents CNS penetration
Phenobarbital	Weak acid; enhanced elimination
Chlorpropamide	Weak acid
Methotrexate	Weak acid
2,4-Dichlorophenoxyacetic acid (herbicide)	Weak acid
Formic acid	Methanol metabolite
Chlorpropamide	Oral hypoglycemic

Mnemonic - CAMPS: Chlorpropamide, Aspirin/salicylates, Methotrexate, Phenobarbital, (2,4-D/herbicides)

Protocol

IV bolus: Sodium bicarbonate 1-2 mEq/kg body weight
Infusion: 3 ampules (150 mEq) of 8.4% NaHCO₃ in 1 L D5W + 20-40 mEq KCl → infuse at 2-3x maintenance rate (up to 250 mL/hr)
Target urine pH: 7.5-8.0 (check hourly)
Target serum pH: 7.45-7.55 (do NOT exceed 7.55)

Critical: Correct Hypokalemia First

Alkalinization causes intracellular shift of K⁺ → hypokalemia → distal tubule compensates by excreting H⁺ in exchange for K⁺ → acidifies urine → defeats the purpose entirely. Always co-administer potassium.

Contraindications

Volume overload
Cerebral or pulmonary edema
Severe alkalemia (pH >7.55)

2. Urinary Acidification ❌ (NOT Recommended)

Mechanism

Lowering urine pH causes weak base drugs (amphetamines, PCP) to become ionized (positively charged) → cannot be reabsorbed → excreted faster.

Why It Is NOT Done

Reason	Explanation
Rhabdomyolysis risk	Amphetamines and PCP commonly cause rhabdomyolysis. Acidifying urine causes myoglobin to precipitate in renal tubules → acute tubular necrosis / acute renal failure
Modest benefit	The increase in elimination doesn't outweigh the renal danger
MAOI overdose	Acidification is ineffective AND predisposes to acute renal failure

"Acidification may increase the urine concentration of drugs such as phencyclidine and amphetamines but is not advised because it may worsen renal complications from rhabdomyolysis, which often accompanies the intoxication." - Katzung

Side-by-Side Comparison

Feature	Urinary Alkalinization	Urinary Acidification
Target drug type	Weak ACIDS	Weak BASES
Mechanism	Ion trapping of anions	Ion trapping of cations
Agent used	IV sodium bicarbonate	Ammonium chloride / ascorbic acid (historical)
Target urine pH	7.5-8.0	<5.5
Key drugs	Salicylates, phenobarbital, methotrexate	Amphetamines, PCP (theoretical only)
Currently recommended?	Yes (for salicylates especially)	No (abandoned - rhabdomyolysis risk)
Major hazard	Hypokalemia (blocks alkalinization), systemic alkalemia	Acute renal failure from myoglobin precipitation
Extra benefit	Prevents CNS penetration of salicylate	None

Key Exam Points

Urinary alkalinization = NaHCO₃ + KCl (always correct hypokalemia)
It is 1st-line for moderate salicylate poisoning not meeting hemodialysis criteria
Urinary acidification is historically taught but clinically abandoned
Forced diuresis alone (without pH change) is also not recommended - causes volume overload without meaningful benefit (except possibly in lithium poisoning)

Sources: Goldman-Cecil Medicine; Goodman & Gilman's Pharmacology; Katzung Basic & Clinical Pharmacology; Rosen's Emergency Medicine; Washington Manual of Medical Therapeutics

Give any tricks to remember poision and antidote

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Poison & Antidote - Memory Tricks

Group 1: The "OPIOID Reversal" Pair - Easy One First

Poison	Antidote	Trick
Opioids (morphine, heroin, fentanyl)	Naloxone	NALoxone = NALls the opioid down. "NALl it shut"
Benzodiazepines (diazepam)	Flumazenil	FLUmazenil FLUshes out the benzo. Flu clears the sedation

Group 2: The Famous Trio - Organophosphates (OP)

"ATROPINE PRALIDOXIME for OPs - ATP for energy, ATPase for nerve"

Poison	Antidote	Trick
Organophosphates / carbamates / nerve agents	Atropine (1st) + Pralidoxime / 2-PAM (2nd)	Atropine for All symptoms (dries secretions), Pralidoxime to Prevent aging of AChE

Atropine blocks muscarinic effects (SLUDGE)

Pralidoxime reactivates AChE if given early (before "aging")

Mnemonic: "AP for OP" = Atropine + Pralidoxime for OrganoPosphate

Group 3: Heavy Metals - The Chelators

"BAD metals need BAL or DMSA"

Poison	Antidote	Trick
Lead	Dimercaprol (BAL) + CaNa₂EDTA or Succimer (DMSA)	Lead = Lots of chelators. "EDTA grabs Lead"
Mercury	Dimercaprol (BAL) / Succimer	Mercury → Mercaprol (both start with Mer-)
Arsenic	Dimercaprol (BAL) / Succimer	Arsenic → BAL (British Anti-Lewisite - used in WWI arsenic warfare)
Iron	Deferoxamine	Deferoxamine Drags out iron = De-iron-amine
Thallium/Cesium	Prussian Blue	Thallium → "Thallium turns Prussian Blue" (used in nuclear accidents)

BAL trick: BAL = Bad Arsenic Lead (+ mercury) - covers all 3

Group 4: Carbon & Cyanide - The "Gas Killers"

Poison	Antidote	Trick
Carbon Monoxide	100% O₂ (± hyperbaric)	CO kicks O₂ off Hb → flood with O₂ to kick CO back off
Cyanide	Hydroxycobalamin (1st line) OR Sodium nitrite + Sodium thiosulfate	"Cyanide → Cyanocobalamin cousin = Hydroxycobalamin"

Cyanide antidote logic:

Nitrite creates methaemoglobin → CN prefers metHb over cytochrome (diverts it)

Thiosulfate donates sulfur → rhodanese converts CN → thiocyanate (harmless, excreted)

Mnemonic: "NiNa NiNa" = Nitrite + Na thiosulfate (like a siren - emergency!)

Group 5: Paracetamol / Acetaminophen

Poison	Antidote	Trick
Paracetamol (APAP)	N-Acetylcysteine (NAC)	"Paracetamol → NACk it with NAC". NAC replenishes glutathione** to neutralize NAPQI

NAPQI is the toxic metabolite. NAC = glutathione substitute. Give within 8-10 hours.

Group 6: Anticoagulants - Reverse the Clot Stoppers

Poison / Drug	Antidote	Trick
Warfarin / Coumarins	Vitamin K₁ (Phytonadione)	War-far-in is far from clotting → K brings it back
Heparin	Protamine sulfate	Heparin → Protamine (Pro is the opposite/antidote)
Dabigatran (direct thrombin inhibitor)	Idarucizumab	Idarucizumab Ida-reverses Dabigatran (Ida ~ reversal of Da)
Rivaroxaban / Apixaban (Xa inhibitors)	Andexanet alfa	Andexanet for Xa (factor Xa inhibitors)

Group 7: Receptor Blockers & Overdoses

Poison	Antidote	Trick
Beta-blockers	Glucagon + High-dose insulin	Glucagon for β-Gone heart rate. Glucagon bypasses the blocked β-receptor
Calcium channel blockers	Calcium + Glucagon + High-dose insulin	CCB → give Calcium to compete
Digoxin/Digitalis	Digoxin-immune Fab	Fabulous Fab fragments Fabulate the digoxin away
Anticholinergic (atropine OD, antihistamines)	Physostigmine	Anticholinergic → Physostigmine (cholinesterase inhibitor = restores ACh)
Methemoglobinemia (nitrites, dapsone)	Methylene Blue	Met-Hb is blue → Methylene Blue fixes blue blood

Group 8: Metabolic Poisons

Poison	Antidote	Trick
Methanol / Ethylene glycol	Fomepizole (4-MP)	Fomepizole Freezes alcohol dehydrogenase - stops toxic metabolite formation
Isoniazid (INH) / Gyromitra mushroom	Pyridoxine (Vit B₆)	INH depletes B₆ → "INH eats B₆, give it back"
Methotrexate	Leucovorin (folinic acid) + Glucarpidase	MTX blocks folate → Leucovorin = Rescue folate
Sulfonylurea hypoglycemia	Octreotide	Octreotide Octopus grabs and stops insulin release
Local anesthetics (bupivacaine toxicity)	Intralipid (IV fat emulsion)	Fat soaks up fat-soluble drug - "lipid sink"

Master Memory Table - "ABCDEFGH" Framework

Letter	Poison	Antidote
A	Acetaminophen	Acetylcysteine (NAC)
B	Benzodiazepines	Flumazenil (Benzo → Flush)
C	Cyanide	Hydroxycobalamin / NaNO₂ + Na-thiosulfate
D	Digoxin	Digoxin-immune Fab
E	Ethylene glycol / mEthanol	Fomepizole
F	Fluoride / Ca-channel blocker	Calcium gluconate
G	β-blockers (Gone HR)	Glucagon
H	Heparin	Protamine
I	Iron	Deferoxamine

Quick-Fire Mnemonics Summary

Mnemonic	Covers
"NAL nails opioids"	Naloxone → opioids
"FLU flushes benzos"	Flumazenil → benzodiazepines
"AP for OP"	Atropine + Pralidoxime → Organophosphates
"BAL for BAd metals"	BAL/Dimercaprol → Lead, Arsenic, Mercury
"De-iron-amine"	Deferoxamine → Iron
"NiNa NiNa"	Nitrite + Na-thiosulfate → Cyanide
"NAC-k Paracetamol"	N-Acetylcysteine → Paracetamol
"Fab-ulous for Digoxin"	Digoxin-immune Fab → Digoxin
"Fomepizole Freezes ADH"	Fomepizole → Methanol / Ethylene glycol
"INH eats B₆"	Pyridoxine → INH / Gyromitra mushroom
"Methylene blue for blue blood"	Methylene blue → MetHb
"Fat sink for fat drugs"	Intralipid → local anesthetic toxicity
"War-farin → War needs K to stop"	Vitamin K → Warfarin
"Prussian Blue for Thallium"	Prussian Blue → Thallium/Cesium

Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics, Table 9-14; Lippincott Illustrated Reviews Pharmacology; Park's Textbook of Preventive and Social Medicine

Acid corrosives vs alkali corrosives

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Acid Corrosives vs Alkali Corrosives

1. Basic Definitions & Examples

Feature	Acid Corrosives	Alkali Corrosives
pH	<7	>7
Common agents	Sulfuric acid (H₂SO₄), Hydrochloric acid (HCl), Nitric acid (HNO₃), Formic acid, Acetic acid	Sodium hydroxide/lye (NaOH), Potassium hydroxide (KOH), Ammonia (NH₃), Sodium hypochlorite (bleach)
Found in	Toilet bowl cleaners, pool cleaners, rust removers, battery acid	Drain cleaners (Drano), oven cleaners, hair relaxers, dish detergents, industrial bleach
Other name	Corrosives	Caustics

2. Mechanism of Injury - THE KEY DIFFERENCE

	Acid	Alkali
Type of necrosis	Coagulation necrosis	Liquefaction necrosis
Mechanism	H⁺ ions denature proteins → form a coagulum (gel-like eschar) on mucosa	OH⁻ ions cause protein denaturation + lipid saponification → deep tissue destruction + microvascular thrombosis
Depth of injury	Coagulum limits penetration - relatively self-limiting	No limiting barrier - penetrates deeply into all tissue layers
Severity	Generally less severe	More severe - progressive, worsening with time

Memory trick: Acid = Armour (coagulum forms a protective shell). Alkali = Attacks everywhere (no barrier, melts through)

3. Anatomical Distribution of Injury

Site	Acid	Alkali
Oropharynx	Less affected (bitter taste + gag reflex limits ingestion)	More affected (especially solid/powder forms - lye crystals)
Esophagus	Relatively spared (coagulum protects) though recent endoscopy data shows equal esophageal injury rates	Primary site of injury (full-thickness burns, circumferential strictures)
Stomach	Main target - acid settles in stomach, increased pH → deeper penetration → pyloric stenosis, gastric outlet obstruction, perforation	Can be affected with large intentional ingestions
Beyond GI	Systemic absorption → metabolic acidosis, hemolysis, renal failure	Deep penetration → mediastinitis, pancreatitis, peritonitis

Trick: Acid hits the Abdomen (stomach). Alkali hits the Airway and Airpipe (esophagus, pharynx)

4. Esophageal Burn Grading (Zargar Classification)

Grade	Endoscopic Finding	Risk
0	Normal	None
1	Mucosal edema + hyperemia	No stricture
IIa	Superficial, non-circumferential ulcers, whitish membranes	Low stricture risk
IIb	Deep, circumferential lesions	High stricture risk
IIIa	Small scattered areas of necrosis	Very high
IIIb	Extensive necrosis	Surgical
IV	Perforation	Emergency surgery

Critical period: Days 2-14 after injury = maximum tissue friability + perforation risk (both spontaneous and iatrogenic)

5. Clinical Features (Both)

Symptom	Mechanism
Vomiting (most common)	Direct mucosal irritation
Dysphagia / odynophagia	Esophageal burn
Drooling	Cannot swallow saliva
Oral/chest/abdominal pain	Mucosal/transmural injury
Hoarseness, stridor	Laryngeal/epiglottic injury - "chemical epiglottitis"
Dribble burns on face/chest	Streaks from spillage - acid ingestion classic sign
Fever + chest pain	Mediastinitis / perforation
Hypotension	Shock (hemorrhage, perforation, third-spacing)

6. Management - What NOT to Do

❌ Contraindicated	Reason
Activated charcoal	Doesn't bind caustics; obscures endoscopy
Emetics / Ipecac	Re-exposes mucosa + airway to caustic on the way back up; can cause perforation
Neutralization (giving acid for alkali and vice versa)	Exothermic reaction → more heat damage + distension + vomiting
Dilution	No proven benefit; causes distension, vomiting
Blind NGT insertion	Risks perforation of injured esophagus
Gastric lavage	Absolute contraindication (perforation risk)
Blind nasotracheal intubation	Can worsen airway injury

7. Management - What TO Do

Step 1 - Airway (FIRST priority)

Approach as difficult airway - oedema worsens with time
Early oral intubation under direct vision
Fiberoptic evaluation before intubation if possible
Cricothyrotomy if intubation impossible

Step 2 - Decontamination

Remove contaminated clothing
Copious water irrigation of skin/eyes
DO NOT neutralize

Step 3 - Investigations

ABG, electrolytes, LFTs, FBC, lactate, blood type & screen
Chest X-ray - look for mediastinal/peritoneal free air
CT thoracoabdomen (IV contrast) - better than endoscopy at predicting stricture depth and need for surgery
Endoscopy - gold standard for grading; do within 12-24 hours; mandatory for all intentional ingestions

Step 4 - Supportive

Large-bore IV + crystalloid resuscitation
Nil by mouth
Analgesia
PPI / H2 blockers

Step 5 - Steroids?

Controversial - one trial showed benefit for grade IIb lesions
Meta-analysis: no clear benefit + may increase infection/perforation risk
Currently not routinely recommended

Side-by-Side Summary

Feature	Acid	Alkali
Necrosis type	Coagulation	Liquefaction
Depth	Superficial (self-limiting eschar)	Deep (progressive, no barrier)
Primary site	Stomach (pyloric stenosis, GOO)	Esophagus (strictures)
Severity	Less severe	More severe
Systemic toxicity	Metabolic acidosis, hemolysis, renal failure	Mediastinitis, pancreatitis, peritonitis
Stricture risk	Lower	Higher (especially Grade IIb+)
Both contraindicated	Lavage, charcoal, emetics, neutralization	Same

Sources: Tintinalli's Emergency Medicine Ch. 200; Cummings Otolaryngology Ch. 211; Rosen's Emergency Medicine; Tintinalli's EM - Alkali Injuries

Give information for undergraduate level with full clarification

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Acid Corrosives vs Alkali Corrosives

Complete Undergraduate Guide

PART 1: INTRODUCTION & DEFINITIONS

A corrosive poison is a chemical agent that destroys living tissue immediately upon contact by direct chemical action, before any systemic absorption is needed. This distinguishes it from a systemic poison (like cyanide) which must be absorbed first to cause harm.

Corrosive = derived from Latin corrodere = "to gnaw through flesh"
Caustic = strictly refers to alkalis/bases, but clinically used interchangeably with "corrosive"
Some agents are BOTH corrosive AND poison (e.g., phenol = local corrosive + systemic CNS depressant)

Two major groups:

Acid corrosives - pH <7
Alkali (caustic) corrosives - pH >7

PART 2: ACID CORROSIVES

2A. SULFURIC ACID (H₂SO₄) - "Oil of Vitriol" - The Most Important

Physical Characters:

Pure form: heavy, odorless, colorless, non-fuming, oily hygroscopic liquid
Commercial form: brown or dark colored (due to impurities)
Causes superficial burns in 1 second; full-thickness burns in 30 seconds
Strongly hygroscopic - absorbs water from tissues causing dehydration injury

Mechanism: Coagulation necrosis - H⁺ ions denature surface proteins → form a hard, leathery coagulum (eschar) → this eschar limits further penetration (self-limiting at mucosa level, BUT not in stomach where acid pools)

Signs & Symptoms (Ingestion):

System	Feature
Lips/mouth	Swollen, excoriated; brown/black streaks from angles of mouth to chin ("dribble burns")
Teeth	Chalky-white
Tongue	Swollen, sodden, black
Throat/esophagus	Burning pain, stridor, odynophagia, dysphagia
Stomach	Epigastric pain spreading all over abdomen; vomiting - vomit is brown/black, mucoid, strongly acid, may contain charred stomach wall shreds
Thirst	Intense, but any attempt to drink causes more vomiting
Bowels	Severe constipation + tenesmus
Voice	Hoarse and husky
Eyes	Sunken; pupils dilated
Sensorium	Mind remains clear till death (classic exam point)

Fatal Dose: 10-15 mL Fatal Period: 12-24 hours

Cause of Death:

Circulatory collapse (shock)
Spasm or edema of glottis → asphyxia
Perforation of stomach → peritonitis
Toxemia
Delayed: hypostatic pneumonia, secondary infection, renal failure, starvation from esophageal stricture

Complications:

Acute	Chronic
Upper airway obstruction	Esophageal stricture/obstruction
GI hemorrhage	Pyloric stenosis
Esophageal/gastric perforation	Vocal cord paralysis
Sepsis	Permanent skin/oropharyngeal scars
Tracheobronchial necrosis, atelectasis

Postmortem Appearances:

External:

Corrosion of lips, mouth, throat, skin at chin angles and hands
Necrotic areas: initially greyish-white → become brown or black and leathery
Examine clothing for burns and stains

Internal:

Upper digestive tract inflamed and edematous even when corrosion is absent
Acid hematin forms in stomach → contents brown or black, gelatinous
Stomach wall soft, friable; gastric mucosa may be detached in patches
Esophageal mucosa shows longitudinal erosions and corrosion
Intestines usually spared; upper duodenum may be affected
Kidneys: swollen, congested; tubules may contain hemoglobin casts
Thickening of wall due to intense inflammatory reaction

Chemical Test:

Barium nitrate or chloride solution → white precipitate of barium sulphate (confirms sulfate)
Strong acid chars organic matter

Circumstances of Poisoning:

Accidental - mistaken for glycerin or castor oil; inhalation in chemical factories
Suicidal - most common
Homicidal - rare (bitter taste, immediate local action, obvious physical changes make detection easy)
Used as abortifacient by vaginal injection
VITRIOLAGE - throwing acid on another person (see below)

2B. VITRIOLAGE (Acid Attack)

"Throwing of sulfuric acid on another individual is known as vitriolage"

Burns are initially painless (due to nerve ending damage)
Penetrating burns - acid devitalizes tissue and predisposes to infection
Repair is slow; scar tissue causes contracture
Blindness if eyes involved
Death from shock or toxemia if extensive area involved
Other agents also used: nitric acid, carbolic acid, corrosive alkali, juice of marking nut (Semecarpus anacardium), calotropis

Medicolegal aspect (BNS Section 124): Causing permanent/partial damage by throwing or administering acid = imprisonment not less than 10 years (up to life) + fine. The fine is paid to the victim.

2C. NITRIC ACID (HNO₃) - "Aqua Fortis" / "Red Spirit of Niter"

Physical Characters:

Clear, colorless, fuming, heavy liquid with peculiar choking odor

Hallmark Feature: YELLOW discoloration of tissues - due to xanthoproteic reaction (reaction with proteins produces picric acid)

Yellow stains on clothing, yellow discoloration of skin, crowns of teeth, urine (brown)

Signs & Symptoms: Same as sulfuric acid PLUS:

More eructation and greater abdominal distension (due to gas formation)
Lachrymation, photophobia on inhalation of fumes → sneezing, coughing, dyspnoea, asphyxia

Fatal Dose: 10-15 mL | Fatal Period: 12-24 hours

Postmortem: Similar to H₂SO₄ but with characteristic YELLOW staining of tissues. May appear brown-black due to acid hematin. Stomach wall soft, friable, ulcerated.

Test: Brown ring test - add ferrous sulphate solution + sulphuric acid to a solution containing nitric acid → brown ring forms at the junction of two fluids

2D. HYDROCHLORIC ACID (HCl) - "Muriatic Acid"

Physical Characters:

Pungent, colorless, fuming liquid
Natural constituent of gastric juice

Key Distinction:

Less corrosive than H₂SO₄
Does not usually corrode skin seriously, but readily destroys mucous membrane
Mucous membrane initially grey or grey-white → later dark

Fatal Dose: 15-20 mL | Fatal Period: 12-24 hours

2E. OXALIC ACID - "Special Organic Acid"

Unique mechanism: Unlike mineral acids, oxalic acid exerts BOTH local corrosive AND systemic toxic effects

Three Phases of Poisoning:

Local/Corrosive phase: Whitened, "bleached" mucosa of esophagus; corrugated with longitudinal erosions; gastric mucosa reddened/black; gelatinous brown stomach contents (acid hematin)
Systemic/Convulsive phase: Hypocalcemia (oxalate binds Ca²⁺) → muscle irritability, tetany, convulsions, numbness/tingling of fingertips and legs, cardiovascular collapse
Delayed phase: Uremia - scanty/suppressed urine with blood, albumin, calcium oxalate crystals; metabolic acidosis; ventricular fibrillation

Postmortem: Kidneys swollen, congested; tubules filled with oxalate crystals; proximal convoluted tubules necrosed

Antidote: Calcium (any form - lime water, calcium lactate, calcium gluconate) - converts oxalate to insoluble calcium oxalate + IV Calcium gluconate 10% 10mL

Test: Barium nitrate → white precipitate of barium oxalate (soluble in HCl/HNO₃)

2F. CARBOLIC ACID (Phenol; C₆H₄OH) - "Carbolism"

Unique features:

BOTH a corrosive AND a systemic poison
Rapidly absorbed through ALL routes (skin, GI, rectum, vagina, serous cavities, wounds, lungs)
Characteristic carbolic/phenolic smell

Fatal Dose: 10-15 g | Fatal Period: 3-4 hours (much faster than mineral acids)

Local Effects:

Skin: burning + numbness (damages nerve endings); hard, cracked, whitish surfaces; deep burns are black; white opaque painless eschar that falls off leaving brown stain
GI: burning pain mouth to stomach; white/grey corrugated mucosa

Systemic Effects (CNS Depressant):

Excitement → narcosis → unconsciousness → death
Respiratory failure (CNS depression)
Dark/smoky brown urine (phenol metabolites - hydroquinone, pyrocatechol)

Test: Add 10% ferric chloride to urine → bluish colour (also positive with salicylates)

Key exam point: Phenol is about 8 times more toxic than Lysol (Lysol = 50% cresol in saponified vegetable oil)

PART 3: ALKALI CORROSIVES (CAUSTIC ALKALIS)

Chief Alkali Poisons:

Sodium hydroxide (NaOH/lye/caustic soda), Potassium hydroxide (KOH), Calcium hydroxide (lime), Ammonia (NH₃/NH₄OH), Ammonium carbonate, Potassium carbonate, Sodium carbonate

Mechanism of Action (The Core Difference from Acids)

The hydroxyl (OH⁻) ion:

Saponification of fats (dissolves cell membranes)
Soluble alkaline proteinases destroy proteins
Cellular dehydration
Exothermic reaction (generates heat - additional damage)
Liquefaction necrosis: OH⁻ passes from molecule to molecule, denaturing each in turn, burrowing deeply → soft, gelatinous, friable eschars
No limiting barrier forms - unlike acid's coagulum, there is no protective layer → injury is PROGRESSIVE and worsens with time

LYE (NaOH) can produce transmural necrosis of esophagus after just 1 second of contact

Primary Site: Esophagus

"Ingestion of an alkali produces severe effects mainly on lining of esophagus, while gastric involvement is less common. Therefore, stricture formation is much more common with alkalis than with acids."

Signs & Symptoms

Feature	Detail
Taste	Acrid, caustic ("soapy")
Vomiting	Vomited matter is alkaline, does not effervesce on contact with ground; thick and slimy at first, later dark altered blood + shreds of mucosa
Bowels	Purging (frequent) with severe pain, straining; motions of mucus and blood
Skin contact	Greyish, soapy, necrotic area
Lips/skin near mouth	Abrasions, blisters, brownish discoloration
GI mucosa	Swollen, soft, grey slough readily detached
Long-term	Esophageal stricture

Fatal Dose:

NaOH/KOH: 5 g
K₂CO₃: 18 g
Na₂CO₃: 30 g
Ammonia: 15-20 mL

Fatal Period: Usually 24 hours

Postmortem Appearances

Marks around mouth: dark, parchment-like
Lips, mouth, throat: evident corrosion
Pronounced inflammatory edema
Esophageal and gastric tissues: corrosion + sliminess (contrast with acid's leathery, dry eschar)
Stomach: similar soft, slimy necrosis

Ammonia Vapor Inhalation

Congestion and watering of eyes
Violent sneezing, coughing, choking
Sudden collapse from suffocation due to inflammation and swelling of glottis
Later: pneumonia

Miniature (Button) Batteries

Contain potassium hydroxide - when swallowed can cause liquefaction necrosis following leakage from battery. Symptoms mostly GI tract.

PART 4: STAGES OF ESOPHAGEAL INJURY (Both Acid & Alkali)

Stage	Timing	Pathology
Acute inflammatory	0-4 days	Edema, hemorrhage, eosinophilic necrosis, bacterial invasion
Ulceration/necrosis	4-7 days	Bacterial invasion, saponification, full-thickness necrosis
Perforation risk	7-21 days	Tissue at its WEAKEST - highest risk of spontaneous or iatrogenic perforation
Cicatrization (scarring)	From ~3rd week, persists years	Excessive scar tissue → stricture formation

⚠️ Do NOT perform endoscopy or pass NG tubes during days 7-21 without extreme caution - this is the highest perforation risk window.

Zargar Endoscopic Grading

Grade	Findings	Risk
0	Normal	None
1	Mucosal edema + hyperemia	No stricture
IIa	Superficial, non-circumferential ulcers, whitish exudates	Low stricture risk
IIb	Deep, circumferential lesions	High stricture risk
IIIa	Small scattered necrosis	Very high
IIIb	Extensive necrosis	Surgical
IV	Perforation	Emergency

PART 5: COMPARATIVE TABLE - ACID vs ALKALI

Feature	Acid Corrosives	Alkali Corrosives
pH	<7	>7
Necrosis type	Coagulation (protein denaturation → hard eschar)	Liquefaction (saponification of fat + protein denaturing → soft, gelatinous eschar)
Depth of injury	Superficial (coagulum limits penetration)	Deep and progressive (no limiting barrier)
Primary injury site	Stomach (acid pools here)	Esophagus (contact during swallowing)
Stricture formation	Less common	Much more common
Vomit character	Brown/black, acid reaction	Alkaline, thick, slimy, does not effervesce
Eschar character	Hard, dry, leathery, brown/black	Soft, gelatinous, slimy, grey
Severity	Less severe overall	More severe (progressive destruction)
Oropharyngeal injury	Bitter taste limits ingestion; less	More severe (especially solid forms)
Systemic toxicity	Metabolic acidosis, hemolysis, renal failure (especially HCl, H₂SO₄)	Mediastinitis, pancreatitis, multi-organ injury (severe intentional ingestions)
Fatal period	12-24 hours	~24 hours

PART 6: GENERAL MANAGEMENT

Do NOT Do (Both Acids and Alkalis)

❌	Reason
Gastric lavage	Risk of perforation through injured tissue
Emetics/Ipecac	Reexposes mucosa + airway to corrosive
Activated charcoal	Doesn't bind corrosives; blocks endoscopy view
Neutralization (acid for alkali or vice versa)	Exothermic reaction + CO₂ gas production → distension + vomiting + rupture
Alkaline carbonates/bicarbonates for acid (internally)	Liberate CO₂ → gastric distension → rupture
Blind NG tube insertion	Perforation
Blind nasotracheal intubation	Worsens airway injury

What TO Do

Airway first - approach as difficult airway; early fiberoptic assessment; early intubation before oedema worsens; tracheostomy if needed

Skin/Eye Burns:

Wash with plenty of water + soap
Acid burns: apply thick paste of magnesium oxide/carbonate (for skin) or sodium bicarbonate solution (for eyes)
Alkali burns: same copious water irrigation

Oral ingestion (if within 5-30 minutes and patient conscious):

Give water or milk (dilution/demulcent) - 250 mL
Demulcents: egg whites, olive oil, milk, starch water, mineral oil, melted butter

IV access + crystalloid resuscitation

NPO + parenteral nutrition for ~1 week, then gradual reintroduction

Endoscopy: within 12-24 hours of ingestion to grade injury (gold standard)

CT scan (IV contrast): Better than endoscopy for predicting stricture and depth; recommended by World Society of Emergency Surgery

Steroids (prednisolone 60 mg/day): Controversial; may prevent stricture formation in Grade IIb - not routinely recommended due to increased perforation/infection risk

Dilation (bougienage): 4 cm mercury-filled bougie daily if stricture develops

Surgery (exploratory laparotomy): If circumferential 2nd/3rd degree burns or gastric necrosis; esophagogastrostomy may be needed

PART 7: MEDICOLEGAL ASPECTS

Aspect	Acid	Alkali
Accidental	Common - mistaken for other liquids, industrial inhalation	Less common
Suicidal	Most cases	Less common than acid
Homicidal	Rare (taste + immediate pain make detection easy)	Rare
Abortifacient	Vaginal injection - acid	Less used
Special crime	VITRIOLAGE (acid throwing) - legally a serious crime	Used less for vitriolage
BNS Section 124	Acid attack = min 10 years imprisonment + fine to victim	Applicable

PART 8: MEMORY TRICKS

Trick	Content
"Acid = Armour"	Coagulation forms a protective eschar - self-limiting
"Alkali = Attacks ALL layers"	Liquefaction, no barrier, progressive
"Acid hits the Abdomen, Alkali hits the Airway/Alimentary tube"	Stomach vs Esophagus predominance
"Alkali Strictures > Acid Strictures"	Because no self-limiting barrier
"Vomit = Acid? Brown/black + acid reaction. Alkali? Slimy, alkaline, no effervesce"	Distinguishing vomit character
"Nitric acid = Yellow"	Xanthoproteic reaction → yellow staining of tissues, teeth, clothing
"Phenol = fast death (3-4h) + brown urine + blue FeCl₃ test"	Unique features of carbolic acid
"Oxalic acid = Convulsions + Crystals"	Hypocalcemia → tetany; oxalate crystals in kidney
"7-21 days = Most dangerous perforation window"	For esophageal tissue post-caustic injury
"No neutralization EVER"	Exothermic + gas → more damage

Sources: The Essentials of Forensic Medicine and Toxicology 36th Ed (2026); Tintinalli's Emergency Medicine; Cummings Otolaryngology; Rosen's Emergency Medicine

Sulpharic acid poisoning

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Here is the complete, dedicated undergraduate account of sulfuric acid poisoning:

Sulfuric Acid (H₂SO₄) Poisoning

Synonyms

Oil of Vitriol (historical name)
"Vitriol" in forensic/legal context

Physical Characteristics

Property	Detail
Appearance	Pure: heavy, colorless, odorless, non-fuming, oily liquid
Commercial form	Brown or dark colored (due to impurities)
Nature	Hygroscopic (absorbs water greedily from tissues)
Special property	Strong tendency to carbonize (char) organic substances
Speed of injury	Superficial burns in 1 second; full-thickness burns in 30 seconds

Mechanism of Injury

Coagulation necrosis:

H⁺ ions denature surface proteins → form a hard, dry, leathery coagulum (eschar)
The coagulum acts as a partial barrier - limits further acid penetration into the esophagus
However, acid flows down to the stomach (lesser curvature → pylorus), where initial pyloric spasm traps acid → deepest injury at the stomach and pylorus
Hygroscopic nature - absorbs water from cells → additional dehydration injury
Exothermic reaction with water in tissues generates heat → thermal injury on top of chemical injury

Signs and Symptoms

Mouth and Face

Lips: swollen and excoriated
Brown or black streaks extending from angles of mouth → sides of chin → front of neck (due to flow of acid = "dribble burns")
Teeth: chalky-white (acid dissolves enamel)
Tongue: swollen, sodden, and black

Throat and Esophagus

Pharyngeal pain - most common presenting symptom
Immediate burning pain, stridor
Drooling, odynophagia, dysphagia
Voice becomes hoarse and husky

Gastrointestinal

Epigastric pain spreading all over the abdomen and thorax
Eructation, nausea, vomiting
Vomit character: brown or black, mucoid, strongly acid, may contain shreds of the charred stomach wall
Intense thirst - but any attempt to drink causes more vomiting
Abdomen becomes distended and very tender
Severe constipation + tenesmus

Systemic

Eyes: sunken; pupils usually dilated
Circulatory collapse (shock) - may cause immediate death
Asphyxia from edema of glottis
Mind remains clear till death (⚠️ classic exam point - sensorium preserved unlike many other poisons)

If the Patient Survives

Late esophageal, gastric and pyloric strictures and stenoses
Permanent scars on skin and oropharynx

Fatal Dose and Period


Fatal Dose	10-15 mL
Fatal Period	12-24 hours

Cause of Death

Immediate	Delayed
1. Circulatory collapse	Hypostatic pneumonia
2. Spasm/edema of glottis → asphyxia	Secondary infection
3. Perforation of stomach → peritonitis	Renal failure
4. Toxemia	Starvation from esophageal stricture

Complications

Acute

Upper airway obstruction and injury
GI hemorrhage
Esophageal and gastric perforation
Sepsis
Tracheobronchial necrosis, atelectasis, obstructive lung injury

Chronic

Esophageal obstruction (stricture)
Pyloric stenosis
Vocal cord paralysis with airway obstruction

Time Course of Esophageal/Gastric Injury

Stage	Timing	What Happens
Acute inflammatory	0-4 days	Edema, hemorrhage, granulation begins
Granulation	4-7 days	Tissue forming, still necrotic
Perforation risk	7-21 days	Tissue at its weakest - maximum perforation risk
Cicatrization (scarring)	From ~3rd week	Stricture formation; may persist for years

Treatment

What NOT to Do

❌	Reason
Gastric lavage	Perforates damaged stomach wall
Emetics	Re-exposes mucosa to acid
Alkaline carbonates or bicarbonates orally	Liberate CO₂ → gastric distension → rupture

What TO Do

Step 1 - Dilute and neutralize in-situ (within 30 minutes of ingestion): Give 250 mL (one-fourth liter) of any of the following:

Water or milk (first choice)
Milk of magnesia
Lime water
Soap suds
Aluminium hydroxide gel

⚠️ Do NOT use alkaline carbonates/bicarbonates (NaHCO₃) - they release CO₂ gas, cause gastric distension and may rupture the stomach

Step 2 - Demulcents (soothing, coating agents): Olive oil, milk, egg whites, starch water, mineral oil, melted butter

Step 3 - Airway:

Tracheostomy if edema of glottis develops

Step 4 - Nothing by mouth:

IV nutrition for ~1 week
Then: liquids → soft food → regular diet gradually

Step 5 - Endoscopy:

Flexible fiberoptic endoscopy within 24-48 hours to assess extent of damage to esophagus and stomach
If circumferential 2nd/3rd degree burns → exploratory laparotomy
If gastric necrosis → esophagogastrostomy

Step 6 - Steroids:

Prednisolone 60 mg/day in divided doses to prevent esophageal stricture
Generally NOT recommended due to increased perforation risk

Step 7 - Stricture management:

4 cm diameter mercury-filled bougie passed daily if stricture develops

Step 8 - Skin burns:

Wash with large amounts of water
Apply paste of magnesium oxide or sodium bicarbonate

Step 9 - Eye burns:

Irrigate with water or sodium bicarbonate solution for 10-15 minutes
Ideal: suspended IV bag providing low-pressure continuous irrigation
Instill a few drops of olive oil or castor oil after irrigation

Step 10 - Symptomatic - analgesia, antibiotics, IV fluids

Postmortem Appearances

External

Corrosion of lips, mouth, throat, skin at chin angles and hands
Necrotic areas: initially greyish-white → become brown or black and leathery
Examine clothing for acid burns and stains
If acid taken from a spoon - lips and mouth may escape injury

Gross pathology image - Stomach in Sulfuric Acid Poisoning:

Stomach in sulfuric acid poisoning - brown-black coagulative necrosis of mucosa with erosions

The stomach shows extensive brown-black coagulation necrosis. The mucosal ridges are more damaged than the intervening furrows. The wall may disintegrate when touched.

Internal

Site	Findings
Esophagus	Squamous epithelium relatively resistant; superficial mucosal reaction; corrosion present but perforation is rare
Stomach	Main target organ - columnar epithelium affected; superficial erosion + coagulation + eschar; greater part may become a soft, spongy, black mass that disintegrates on touch; acid follows lesser curvature to pylorus → pyloric region most severely affected
Stomach contents	Dark brown/black from acid hematin; altered blood; gelatinous; calcium oxalate crystals may be present
Peritoneum	Chemical peritonitis + corrosion of organs if perforation occurs
Duodenum	Similar but less intense changes
Small intestine	Signs of irritation
Larynx/Trachea	Corrosion or severe inflammation if acid inhaled
Liver/Kidneys	Secondary toxic swelling if patient survives longer; renal tubular necrosis (proximal convoluted tubules primarily)
Diaphragm	May show perforation in severe cases

⚠️ Important: In many cases, little or no free acid is found in viscera at autopsy - because the acid is converted to substances normally present in the body, especially if victim survived 2+ days

Chemical / Forensic Tests

The only suitable material for analysis is the stomach contents

Test	Result
Strong acid + organic matter	Chars organic material
Barium nitrate or barium chloride solution added to stomach contents	White precipitate of barium sulphate confirms sulfate/sulfuric acid

Circumstances of Poisoning

Mode	Details
Suicidal	Most common
Accidental	Mistaken for glycerin or castor oil; inhalation in chemical factories
Homicidal	Rare - acid taste, immediate action, and obvious physical changes make detection easy
Abortifacient	Injected into vagina; also used out of vengeance
VITRIOLAGE	Throwing acid on another person (see below)

Vitriolage (Acid Throwing)

Severe disfiguring acid burns from vitriolage - black necrotic patches with surrounding areas of destruction

Burns are initially painless (acid destroys nerve endings)
Penetrating burns - devitalizes tissues, predisposes to infection
Slow repair; scar tissue causes contracture and disfigurement
Blindness if eyes involved
Death from shock or toxemia if extensive body area involved
Other agents also used: HNO₃, carbolic acid, caustic alkali, juice of marking nut, calotropis

Medicolegal Aspect

BNS (Bharatiya Nyaya Sanhita) Section 124: Acid attack causing permanent/partial damage = imprisonment of not less than 10 years (may extend to life) + fine payable directly to the victim

Quick Revision - Bullet Points for Exams

Sulfuric acid = Oil of Vitriol

Superficial burns in 1 second; full-thickness in 30 seconds

Mechanism = Coagulation necrosis + hygroscopic dehydration

Most common presenting symptom = pharyngeal pain

Teeth = chalky-white; Tongue = swollen, black

Vomit = brown/black, strongly acid

Mind remains clear till death

Fatal dose = 10-15 mL; Fatal period = 12-24 hours

Stomach most affected (not esophagus) - acid pools at pylorus

No carbonates/bicarbonates internally - gas + rupture

No gastric lavage, no emetics

Postmortem = brown/black leathery eschar; stomach like soft spongy black mass

Test = Barium sulphate white precipitate with barium nitrate/chloride

Most cases = suicidal; Vitriolage = throwing acid on others

Source: The Essentials of Forensic Medicine and Toxicology, 36th Edition (2026)

Oxalic acid poisoning

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Complete data from three forensic textbooks. Here is the full undergraduate-level account:

Oxalic Acid Poisoning

Basic Information

Property	Detail
Chemical name	Oxalic acid (C₂H₂O₄)
Synonyms	Acid of sugar, Salt of sorrel
Type	Organic corrosive acid
Appearance	Colorless, transparent, prismatic crystals
Confusion	Closely resembles magnesium sulphate and zinc sulphate in appearance - common cause of accidental poisoning
Natural source	Natural constituent of many plants - spinach, rhubarb, cabbage, sorrel; ~20 mg excreted in urine daily

Differentiation from Magnesium Sulphate (Important Exam Table)

Feature	Oxalic Acid	Magnesium Sulphate	Zinc Sulphate
Taste	Sour and acidic	Bitter and nauseating	Bitter and metallic
Reaction (pH)	Strongly acidic (<7)	Neutral (7)	Slightly acid
On heating	Sublimes (evaporates directly)	Fixed (does not sublime)	Fixed
With sodium carbonate	Effervesces but no precipitate	No effervesce; white precipitate	No effervesce; white precipitate
Ink/iron stains	Bleaches them	No action	No action

Memory trick: OA - Oxalic Acid = Sour + Sublimes + Stain-bleacher (3 S's)

Uses (Why It Is Available)

Commercial uses:

Calico printing
Cleaning brass, copper articles, wooden surfaces, leather
Manufacture of straw hats
Photography
Bookbinding

Domestic use:

Common household remedy for removing ink stains and iron marks from clothing

Illegal use:

Used to erase writing and signatures from paper (document forgery)

Mode of Action - The Three-System Attack

Oxalic acid is unique among corrosive acids - it has BOTH local AND systemic (remote) actions.

1. Local Action (Corrosive)

Crystals and solutions >10% concentration → corrosive to mucous membranes of GI tract
Rarely damages skin
Less than 10% solution → irritant (still causes serious systemic effects after absorption)
Does NOT lose poisonous properties when diluted (unlike some other poisons)

2. Systemic Action - Hypocalcaemia (KEY FEATURE)

Oxalic acid + Ca²⁺ in blood/tissues → insoluble calcium oxalate

This reaction:

Removes ionised calcium from circulation → hypocalcaemia
Calcium oxalate crystals deposit in kidney tubules → tubular necrosis
Low serum calcium → tetany, convulsions, cardiac arrhythmias

3. Systemic Action - Shock

Large doses cause rapid death from circulatory shock (narcotic effect on cardiovascular system)

Fatal Dose and Period


Fatal Dose	15-30 g (smallest recorded: 5 g)
Fatal Period	1-2 hours (longest recorded: 5 days)

Signs and Symptoms - Three Phases

Phase 1: Fulminating Poisoning (Large dose ≥15 g - death within minutes)

Symptom	Detail
Taste	Burning, sour, bitter taste in mouth
Throat	Sense of constriction around throat
Pain	Burning pain mouth → stomach; starts epigastric → radiates all over abdomen; tenderness
Vomiting	Nausea, eructations → persistent vomiting; vomit = "coffee-ground" (altered blood + mucus)
Thirst	May be present
Bowels	Usually unaffected (death too fast); if life prolonged → diarrhoea
Death	Before bowels are affected - within minutes

Phase 2: Acute Poisoning (Large dose - patient survives hours)

Dominated by hypocalcaemia symptoms:

Symptom	Mechanism
Muscle irritability and tenderness	Low Ca²⁺ increases neuromuscular excitability
Tetany → Convulsions	Severe hypocalcaemia → seizures
Numbness and tingling of fingertips and legs	Peripheral nerve irritability
Cardiovascular collapse	Low Ca²⁺ → cardiac dysfunction
Stupor and coma	In some cases

Phase 3: Delayed Poisoning (Death in 2-14 days from renal failure)

Symptoms of uraemia:

Scanty or suppressed urine (oliguria/anuria)
Urine contains: blood, albumin, calcium oxalate crystals
Oxaluria = calcium oxalate crystals in urine (envelope-shaped under microscope)
Metabolic acidosis
Ventricular fibrillation

Treatment

Step 1 - Gastric Lavage

Since corrosion is less severe than mineral acids, a soft stomach tube can be passed with care
Lavage performed using calcium lactate or gluconate (2 teaspoonfuls in each lavage aliquot)
Do NOT use warm water - warm water dissolves more acid and increases absorption

Step 2 - Antidote: CALCIUM (any preparation)

Calcium + oxalate → insoluble calcium oxalate → harmless, cannot be absorbed

Options:

Chalk (calcium carbonate) suspension - 30 g chalk in water or milk neutralizes ~20 g oxalic acid (most readily available)
Lime water
Calcium lactate
Calcium gluconate (oral)
Calcium gluconate 10%, 10 mL IV at regular intervals (for systemic hypocalcaemia)

⚠️ Do NOT give alkalis (soda/potash/ammonia) - their oxalates are soluble and increase absorption

Step 3 - Severe Hypocalcaemia

Parathyroid extract 100 units IM in severe cases

Step 4 - Renal Monitoring

Check urinary output to detect renal damage
Control fluid intake accordingly

Step 5 - Other Measures

Demulcent drinks
Bowels may be evacuated by enema or castor oil
Dialysis or exchange transfusion for renal failure
Symptomatic treatment

Postmortem Appearances

External

Skin is rarely burned (unlike mineral acids)
No staining of lips/chin (important difference from sulfuric/nitric acid)

Internal - Mouth and Oesophagus

Mucous membrane of tongue, mouth, throat, oesophagus: white, as if bleached (sometimes reddened by irritation)
Oesophagus shows corrugated surface with longitudinal erosion

Internal - Stomach

Outer coat: inflamed and reddened; patchy softening
Stomach contents: brownish, gelatinous (due to acid haematin formation)
Mucous membrane: corroded and detached in degrees depending on concentration
Blood vessels in submucous layer visible as dark lines (due to acid haematin)
Perforation is rare
If death is immediate: stomach may be pale and not corroded
If whole stomach affected: corroded and perforated in severe cases

Internal - Kidneys (Pathognomonic Feature)

Kidneys: swollen, congested; renal tubules filled with calcium oxalate crystals Tubular necrosis primarily in proximal convoluted tubules

Calcium oxalate crystals: envelope-shaped under microscope

Internal - If Only Narcotic Effect (No Local Damage)

Congestion of lungs, liver, kidneys, brain - without any local GI changes

If Death Delayed

Inflammation of upper small intestine
Kidney changes (oxaluria, tubular necrosis)

Chemical Test

Test	Result
Add barium nitrate solution to suspected material	White precipitate of barium oxalate (soluble in HCl or HNO₃ - distinguishes from barium sulphate which is insoluble)
Urine with 10% ferric chloride	Not applicable (ferric chloride is for phenol)
Strong acid chars organic matter	Not applicable to oxalic acid (sublimes)

Material for analysis: Stomach contents

Medicolegal Aspects

Mode	Details
Accidental	Most common - frequently mistaken for magnesium sulphate or sodium bicarbonate (similar crystal appearance). Also: rhubarb leaves used as vegetables
Suicidal	Occasionally - sour taste limits willingness
Homicidal	Very rare - sour/bitter taste is detectable; rapid action makes it obvious
Abortifacient	Rarely used
Forgery	Used to erase writing and signatures from paper
Special note	Oxalic acid solutions poured on head cause falling off of hair

Summary Comparison - Oxalic Acid vs Other Acids

Feature	Sulfuric Acid	Oxalic Acid
Type	Inorganic/mineral	Organic
Necrosis	Coagulation (hard, leathery)	Coagulation (softer, bleached)
Skin burns	Yes - prominent	Rare
Lip/chin staining	Yes - brown/black	No staining
Main systemic toxicity	Shock, renal failure	Hypocalcaemia → tetany/convulsions + renal failure
Gastric lavage	Contraindicated	Allowed with care (soft tube + calcium solution)
Antidote	None specific (demulcents)	Calcium (precipitates oxalate)
Crystal deposits	None	Calcium oxalate crystals in kidney (envelope-shaped)
Fatal period	12-24 hours	1-2 hours (faster)
Postmortem stomach	Black, leathery, soft spongy mass	Brownish gelatinous; white bleached mucosa
Confusion with	-	Magnesium sulphate (appearance)

Memory Tricks

Trick	Content
"OA = Oxalate grabs cAlcium"	Oxalic Acid → Hypocalcaemia
"Tetany, Twitching, Tingling = Think Oxalic"	3 T's of hypocalcaemia
"Coffee-ground vomit + Convulsions"	Unique combination pointing to oxalic acid
"Antidote = Chalk/Calcium - makes insoluble crystals"	Calcium precipitates oxalate
"No soda/alkali - their oxalates are SOLUBLE"	Avoid NaOH/NaHCO₃ as antidote
"Envelope crystals in kidney"	Calcium oxalate on microscopy
"Sublimes on heating - not magnesium sulphate"	Distinguishing test
"No lip staining"	Unlike H₂SO₄ and HNO₃

Sources: The Essentials of Forensic Medicine and Toxicology 36th Ed (2026); Parikh's Textbook of Medical Jurisprudence; P.C. Dikshit Textbook of Forensic Medicine and Toxicology

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