History Points in a Patient with Upper GI Bleed

1. Presenting Complaint - Nature of Bleeding

• Hematemesis - bright red blood or "coffee-ground" vomiting (digested blood)
• Melena - black, tarry, foul-smelling stools (blood from proximal to ligament of Treitz)
• Hematochezia - fresh red blood PR; seen in ~10-15% of UGIB and implies a brisk, massive bleed
• Onset, duration, volume/quantity of blood lost, number of episodes

2. Associated Symptoms (Clues to Severity & Cause)

3. Drug & Substance History

• NSAIDs / Aspirin (including OTC) - strongly associated with peptic ulcer bleeding
• Anticoagulants - warfarin, DOACs (risk stratification; INR ≥1.5 predicts increased mortality)
• Antiplatelets - clopidogrel, ticagrelor
• Corticosteroids - increase ulcer risk especially with NSAIDs
• Herbal supplements - some contain salicylates
• Alcohol - heavy intake suggests Mallory-Weiss tear or alcoholic gastritis/varices
• Iron / bismuth - can mimic melena (black stools without bleeding)

4. Past Medical History

• Peptic ulcer disease - most common cause (~38-40% of UGIB)
• Liver disease / cirrhosis - portal hypertension raises suspicion for varices or portal hypertensive gastropathy
• GERD - erosive esophagitis
• Previous GI surgery - surgical anastomosis, aortic graft (aortoenteric fistula)
• Coagulopathy / haematological disorders - thrombocytopenia, haemophilia
• Renal failure - platelet dysfunction, uraemia
• Cardiovascular disease - affects transfusion targets
• History of previous GI bleed - prior episodes, previous endoscopy/treatment

5. Family History

• GI malignancy
• Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu)
• Inflammatory bowel disease

6. Feeding Tubes / Instrumentation

• Chronic nasogastric tube - raises suspicion for erosive esophagitis
• Recent endoscopy, instrumentation, or surgery (iatrogenic causes)

7. History Clues for Specific Diagnoses

8. Social History

• Alcohol intake (quantity, duration, type)
• Smoking (increases peptic ulcer risk)
• NSAID/analgesic self-medication (often under-reported)
• Travel history (infectious causes, though less common)

9. Review of Systems / Functional Enquiry

• Signs of chronic liver disease: jaundice, easy bruising, peripheral oedema
• Weight loss, night sweats (malignancy)
• Dysphagia (tumour, stricture)
• Recent vomiting/retching prior to haematemesis (Mallory-Weiss)

Upper GI Bleed - Differential Diagnosis by History

At a Glance

Differential Diagnosis by History - Comparison Table

Quick "Pattern Recognition" Summary

Clinical Analysis: 5-Day SOB + Dry Cough | Smoker + Barbeque Worker

Patient Summary

Key Pathophysiological Context

1. Cigarette smoke - 6 years (tobacco combustion products, acrolein, carbon monoxide, particulates)
2. Barbeque/combustion smoke - 10 years daily (wood smoke, charcoal combustion, polycyclic aromatic hydrocarbons, carbon monoxide, fine particulate matter <2.5 µm, acrolein, nitrogen dioxide)

Differential Diagnoses

TIER 1 - Most Likely (Given History)

1. Early / Acute COPD Exacerbation

• Why: 6 years of smoking + 10 years of chronic smoke/particulate exposure = synergistic risk. COPD burden is estimated at 15-20% attributable to occupational factors even without smoking.
• Supporting features: Subacute onset over days; dry or minimally productive cough early on; small airway obstruction from smoke causes mucus dysfunction and ciliary impairment.
• Pattern: SOB on exertion worsening progressively; fine particulates <2.5 µm penetrate to bronchioles and alveoli causing small airway disease.
• Ask about: Morning cough, exercise tolerance over past months, any prior episodes.

2. Occupational Asthma / Work-Aggravated Asthma

• Why: Barbeque smoke contains multiple sensitising agents - wood smoke, combustion gases, organic particles. Occupational asthma accounts for up to 15-20% of adult-onset asthma.
• Supporting features: Dry cough + SOB; possible nocturnal or early morning worsening; symptoms may improve on days off work (a critical clue).
• Key history question: "Are symptoms better on weekends or holidays?" - a YES here strongly points to occupational asthma.
• Pattern: Airway hyperreactivity, bronchospasm; FEV1 drop may be demonstrable pre- vs. post-work shift.

3. Smoke Inhalation / Irritant-Induced Airways Disease

• Why: Chronic barbeque smoke = chronic low-level irritant exposure. Wood smoke and charcoal smoke contain acrolein (a potent MUC5AC inducer) and fine particulates that deposit at bronchiolar level.
• Supporting features: Dry cough; acute-on-chronic presentation (5 days of worsening = possible new heavy exposure episode or seasonal busy period at work).
• Pattern: Reactive airways dysfunction syndrome (RADS) - persistent asthma-like symptoms following high-level irritant exposure.

TIER 2 - Important to Exclude

4. Hypersensitivity Pneumonitis (HP) / Extrinsic Allergic Alveolitis

• Why: Organic dusts and protein antigens from cooking/barbeque (animal proteins, fungal spores in poorly stored wood) can cause HP. Distinct from simple irritant disease.
• Supporting features: Dry cough + SOB; subacute form presents over weeks-months; may have constitutional symptoms (malaise, low-grade fever, weight loss).
• Pattern: Restrictive + decreased diffusion capacity on PFTs; bilateral infiltrates on imaging.
• Ask about: Fever, chills, myalgia 4-6 hours after work exposure (classic subacute HP "flu-like" attacks).

5. Pneumonia / Lower Respiratory Tract Infection

• Why: Sudden 5-day history in a smoker - who has impaired mucociliary clearance - makes them more susceptible to community-acquired pneumonia (CAP) or atypical pneumonia.
• Supporting features: Dry cough can be early pneumonia (especially atypical organisms: Mycoplasma, Legionella, Chlamydophila).
• Distinguish by: Fever, rigors, pleuritic chest pain, sputum production, crackles on auscultation.
• Note: Smokers have 2-4x higher risk of CAP.

6. Pulmonary Embolism (PE)

• Why: Sudden-onset SOB + dry cough is a classic PE presentation. Never miss.
• Supporting features: The "sudden" qualifier in the history is important; PE can occur in otherwise healthy individuals.
• Ask about: Recent immobility, long travel, leg swelling, pleuritic chest pain, haemoptysis, prior DVT/PE.
• Risk assessment: Use Wells score; if PE unlikely can be further assessed with D-dimer.

7. Interstitial Lung Disease (ILD) / Pneumoconiosis (Early)

• Why: 10 years of particulate inhalation from barbeque smoke (carbon, organic particulates) and cigarette smoke can cause smoking-related ILD (desquamative interstitial pneumonia, respiratory bronchiolitis-ILD, or early fibrosis).
• Supporting features: Dry cough; progressive exertional SOB; may not yet have crackles.
• Pattern: HRCT is more sensitive than CXR for early interstitial changes; restrictive pattern on spirometry.
• Note: ILD from carbon/smoke is less abrupt in onset - would explain a longer background of worsening function with acute decompensation now.

8. Carbon Monoxide (CO) Poisoning / Chronic CO Exposure

• Why: Barbeque shops using charcoal generate significant CO, especially in poorly ventilated spaces. Chronic sub-lethal CO exposure causes headache, SOB, and cognitive impairment.
• Supporting features: SOB, dry cough; no fever; "sudden" deterioration possible if ventilation worsened.
• Ask about: Headaches, dizziness, colleagues with similar symptoms, ventilation of workplace.
• Important: CO-oximetry (COHb) - standard SpO2 pulse oximetry will be falsely normal.

TIER 3 - Consider in Context

Priority Further History to Take

Immediate Investigations to Recommend

• pH 7.48 → Alkalosis
• PaCO2 16 mmHg → Respiratory alkalosis (primary - CO2 blown off by hyperventilation)
• HCO3 21 → Slightly low (mild metabolic compensation or mixed)
• SpO2 99% on room air → NOT hypoxic (but CO-oximetry needed!)

⚠️ CRITICAL CASE ANALYSIS

Step 1 - ABG Interpretation

• Severe hyperventilation blowing off CO2
• The patient is NOT hypoxic by pulse oximetry - yet they are severely tachypnoeic and haemodynamically unstable
• This dissociation between clinical severity and SpO2 is the critical clue

⚡ THE DIAGNOSIS: CARBON MONOXIDE (CO) POISONING - Moderate to Severe

Why CO Poisoning Is the Primary Diagnosis

"Carbon monoxide binds haemoglobin with an affinity approximately 250 times that of oxygen. The resultant carboxyhemoglobin (HbCO) leaves less haemoglobin available for binding oxygen and shifts the O2-Hb dissociation curve to the left... Pulse oximetry provides a falsely elevated indication of oxygen saturation in the setting of carbon monoxide exposure because of its inability to distinguish oxygenated haemoglobin from HbCO." - Morgan & Mikhail's Clinical Anaesthesiology, 7th ed.

Supporting Clinical Logic (Why NOT Other Diagnoses)

IMMEDIATE NEXT STEPS (Do These NOW)

🔴 Priority 1 - Confirm Diagnosis

• Order immediately from arterial or venous blood gas with CO-oximetry (standard ABG machine must have co-oximeter)
• Standard ABG alone will NOT give this - must specifically request CO-oximetry
• Normal smoker: COHb up to 5-10% (due to cigarette smoking)
• Clinically significant: >10%
• Severe: >25-30% (neurological symptoms)
• Requires intubation: >20% with symptoms or >40% any level
• Death: >60%

MANAGEMENT - 2025/2026 Guidelines

Phase 1 - Immediate Resuscitation

Phase 2 - Hyperbaric Oxygen (HBO2) Assessment

HBO2 protocol: Up to 3 atmospheres absolute (ATA) for 1-3 sessions or to clinical plateau. First session ideally within 6 hours of exposure.

"Hyperbaric oxygen should be considered for all cases of acute symptomatic CO poisoning. HBO2 hastens COHb elimination and favourably modulates inflammatory processes instigated by CO poisoning - an effect not observed with normobaric oxygen alone." - Weaver LK, Undersea Hyperb Med, 2024 [PMID: 39348519]

Phase 3 - Ongoing Management

Summary Flow

SpO2 99% + Severe Tachypnoea + Haemodynamic Instability + Barbeque Worker
         ↓
DO NOT TRUST THE SpO2 → CO poisoning until proven otherwise
         ↓
START 100% O2 via NRB IMMEDIATELY (before results)
         ↓
Order: CO-oximetry | ECG | Troponin | Lactate | IV access | Fluids
         ↓
COHb Result Returns:
  >10% symptomatic → Confirm CO poisoning, escalate O2
  >20% + symptoms  → Intubate + FiO2 1.0
  Any significant + neurological/cardiac → Refer for HBO2 within 6 hours
         ↓
If haemodynamics do not respond to fluids → Noradrenaline (SSC 2026)
         ↓
Monitor for delayed neuropsychiatric syndrome (DNS) over following weeks

One Last Critical Point

• Occupational health referral
• Workplace CO monitoring assessment
• Spirometry and lung function testing (COPD/occupational lung disease screening)
• Long-term neuropsychological assessment