Hypotension
Reading Document
Medical Text Search
hypotension causes classification diagnosis management
Medical Text Search
hypotension orthostatic shock treatment blood pressure
GradeResponse
GradeResponse
The retrieved results are limited, so I'll supplement with comprehensive medical knowledge to provide a thorough overview.
Hypotension
Definition
Hypotension is generally defined as a systolic blood pressure (SBP) < 90 mmHg, a diastolic BP < 60 mmHg, or a mean arterial pressure (MAP) < 65 mmHg. In hypertensive patients, a drop of ≥ 20–25% from baseline may be clinically significant even if absolute values remain above these thresholds.
Classification & Etiology
1. Absolute Hypotension (Systemic)
| Category | Examples |
|---|---|
| Hypovolemic | Hemorrhage, dehydration, burns, GI losses, third-spacing |
| Cardiogenic | MI, heart failure, arrhythmias, cardiomyopathy, severe valvular disease |
| Distributive | Septic shock, anaphylaxis, neurogenic shock, adrenal insufficiency |
| Obstructive | Pulmonary embolism, tension pneumothorax, cardiac tamponade, aortic stenosis |
| Iatrogenic / Drug-induced | Antihypertensives, diuretics, opioids, anesthetics, nitrates |
2. Orthostatic (Postural) Hypotension
A drop of ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes of standing.
Causes:
- Autonomic dysfunction (Parkinson's disease, diabetes mellitus, pure autonomic failure, multiple system atrophy)
- Volume depletion
- Medications (alpha-blockers, diuretics, tricyclics, antipsychotics)
- Prolonged bed rest / deconditioning
- Aging (impaired baroreflex sensitivity)
3. Postprandial Hypotension
BP drop > 20 mmHg within 2 hours of a meal; common in elderly and autonomic neuropathy.
4. Postoperative Hypotension
(Bailey & Love, p. 341): Associated with adverse outcomes; often due to hypovolaemia, myocardial impairment, or vasodilation from neuraxial (subarachnoid/epidural) anaesthesia.
Pathophysiology
Blood pressure = Cardiac Output (CO) × Systemic Vascular Resistance (SVR)
CO = Heart Rate × Stroke Volume
CO = Heart Rate × Stroke Volume
Hypotension results from:
- ↓ Preload (hypovolemia)
- ↓ Contractility (cardiogenic)
- ↓ SVR (distributive)
- ↓ Venous return (obstructive)
Clinical Presentation
| Severity | Features |
|---|---|
| Mild | Lightheadedness, dizziness, fatigue |
| Moderate | Syncope or presyncope, blurred vision, diaphoresis, pallor |
| Severe / Shock | Altered consciousness, cold/clammy extremities, oliguria, cyanosis |
Diagnosis
History
- Onset, triggers (posture, meals, medications)
- Volume status (fluid intake, bleeding, diarrhea)
- Comorbidities (cardiac disease, diabetes, Parkinson's)
- Full medication review
Examination
- Orthostatic vitals (supine, sitting, standing BP/HR)
- Skin: warm/flushed (distributive) vs. cold/clammy (cardiogenic/hypovolemic)
- Jugular venous pressure, heart sounds, lung auscultation
- Capillary refill, pulse volume
Investigations
| Test | Purpose |
|---|---|
| FBC, U&E, creatinine | Anemia, renal impairment, electrolytes |
| Blood glucose | Hypoglycemia-associated symptoms |
| Lactate | Tissue perfusion / shock severity |
| ECG | Arrhythmia, myocardial ischemia |
| Echo | Cardiogenic cause, tamponade, valvular disease |
| CTPA / CXR | PE, pneumothorax |
| Blood cultures | Sepsis |
| Cortisol / short synacthen | Adrenal insufficiency |
| Autonomic function tests | Orthostatic hypotension workup |
Management
General / Acute
- Position: Supine with legs elevated (Trendelenburg) if no contraindication
- IV access + fluid resuscitation (crystalloids, colloids, blood products as indicated)
- Treat the underlying cause (source control for sepsis, reperfusion for MI, pericardiocentesis for tamponade, decompression for pneumothorax)
- Vasopressors (if MAP < 65 mmHg despite adequate fluid resuscitation):
- Norepinephrine — first-line in septic shock
- Dopamine — alternative (higher risk of arrhythmia)
- Vasopressin — adjunct
- Phenylephrine — neurogenic/anaphylactic shock
- Inotropes (cardiogenic shock): dobutamine, milrinone
Orthostatic Hypotension (Harrison's, p. 709)
Step 1 — Remove reversible causes: withdraw or reduce vasoactive medications.
Step 2 — Non-pharmacologic interventions:
- Patient education on staged posture changes (supine → sitting → standing)
- Avoid large meals; avoid hot environments
- Isometric counterpressure maneuvers (leg crossing, squatting)
- Raise head of bed 10–20° to reduce supine hypertension and nocturnal diuresis
- Increase dietary fluid and salt intake
- Compression stockings / abdominal binders
Step 3 — Pharmacologic (if above fails):
- Fludrocortisone (mineralocorticoid; expands plasma volume)
- Midodrine (alpha-1 agonist vasoconstrictor)
- Droxidopa (L-DOPS) — norepinephrine prodrug; used in neurogenic orthostatic hypotension
Complications of Untreated Hypotension
- Syncope and falls (especially in elderly)
- Acute kidney injury (renal hypoperfusion)
- Myocardial ischemia
- Stroke / TIA
- Multi-organ dysfunction syndrome (shock)
- Death
Special Populations
| Population | Consideration |
|---|---|
| Elderly | Impaired baroreflex; polypharmacy; higher fall risk |
| Pregnant | Aortocaval compression in supine position; left lateral tilt required |
| Septic shock | Target MAP ≥ 65 mmHg; norepinephrine first-line (Surviving Sepsis Campaign) |
| Spinal cord injury | Neurogenic shock — loss of sympathetic tone; bradycardia + hypotension |
| Postoperative | Hypovolemia, anesthetic agents, bleeding — must be rapidly identified (Bailey & Love, p. 341) |
Sources: Harrison's Principles of Internal Medicine, 21st Ed. (p. 709) | Bailey & Love's Short Practice of Surgery, 28th Ed. (p. 341)
Septic shock
Medical Text Search
septic shock definition diagnosis criteria Sepsis-3
Medical Text Search
septic shock management treatment antibiotics vasopressors fluid resuscitation
GradeResponse
GradeResponse
Septic Shock
Definition (Sepsis-3 Criteria)
(Harrison's, p. 8257)
Sepsis = Suspected infection + acute organ dysfunction (SOFA score increase ≥ 2 points from baseline)
Septic shock = Sepsis plus all of the following despite adequate fluid resuscitation:
- Vasopressor therapy required to maintain MAP ≥ 65 mmHg
- Serum lactate > 2.0 mmol/L
This distinguishes septic shock from uncomplicated sepsis and identifies patients with the highest mortality (> 40%).
qSOFA (quick SOFA) — bedside screening tool (does not require labs):
- Altered mental status (GCS < 15)
- Respiratory rate ≥ 22 breaths/min
- SBP ≤ 100 mmHg ≥ 2 of 3 = high suspicion for sepsis/poor outcome; prompt full SOFA assessment
Pathophysiology
- Infection → systemic immune activation → release of PAMPs (e.g., LPS from gram-negatives, teichoic acid from gram-positives)
- Cytokine storm (TNF-α, IL-1, IL-6) → endothelial dysfunction + widespread vasodilation
- ↓ SVR → distributive shock → relative hypovolemia
- Microvascular thrombosis + tissue hypoperfusion → cellular hypoxia → lactic acidosis
- Myocardial depression (septic cardiomyopathy) — further reduces CO
- Multi-organ dysfunction syndrome (MODS) — kidneys, liver, lungs (ARDS), coagulation (DIC)
Common Sources & Organisms
| Source | Common Pathogens |
|---|---|
| Lung (pneumonia) | S. pneumoniae, Klebsiella, Pseudomonas |
| Urinary tract | E. coli, Klebsiella, Enterococcus |
| Abdomen (peritonitis) | Mixed gram-negatives, Bacteroides, Enterococcus |
| Skin / soft tissue | S. aureus (MRSA), Group A Streptococcus |
| Bloodstream (catheter) | Staph. epidermidis, Candida, S. aureus |
| CNS (meningitis) | N. meningitidis, S. pneumoniae |
Clinical Presentation
| System | Features |
|---|---|
| Cardiovascular | Hypotension, tachycardia, warm/flushed skin (early); cold/clammy (late) |
| Respiratory | Tachypnea, hypoxia, ARDS |
| Neurological | Confusion, agitation, obtundation |
| Renal | Oliguria, rising creatinine |
| GI/Hepatic | Ileus, jaundice, elevated transaminases |
| Haematological | Thrombocytopenia, DIC, leukocytosis or leukopenia |
| Metabolic | Elevated lactate, metabolic acidosis, hyperglycemia |
SOFA Score (Organ Dysfunction Assessment)
| Organ System | Parameters Scored |
|---|---|
| Respiratory | PaO₂/FiO₂ ratio |
| Coagulation | Platelets |
| Liver | Bilirubin |
| Cardiovascular | MAP / vasopressor requirement |
| CNS | Glasgow Coma Scale |
| Renal | Creatinine / urine output |
Score 0–24; higher = greater dysfunction; score ≥ 2 above baseline = sepsis-defining organ failure.
Investigations
| Test | Purpose |
|---|---|
| Blood cultures (×2) | Identify organism — obtain before antibiotics |
| FBC, CRP, procalcitonin | Infection severity, monitoring |
| Serum lactate | Tissue hypoperfusion; guides resuscitation |
| ABG | Acid-base status, PaO₂/FiO₂ |
| U&E, creatinine, LFTs | Organ dysfunction |
| Coagulation screen (INR, APTT, fibrinogen, D-dimer) | DIC |
| Urine culture, CXR, CT abdomen/pelvis | Source identification |
| Focused cardiac ultrasound (POCUS) | Volume status, cardiac function, tamponade |
Management
(Harrison's, p. 8273 | Surviving Sepsis Campaign Guidelines)
The "Hour-1 Bundle" (initiate within 1 hour of recognition)
- Measure lactate (re-measure if initial > 2 mmol/L)
- Obtain blood cultures before antibiotics
- Administer broad-spectrum antibiotics
- Begin IV crystalloid 30 mL/kg for hypotension or lactate ≥ 4 mmol/L
- Apply vasopressors if MAP < 65 mmHg despite fluids
1. Fluid Resuscitation
- IV crystalloid 30 mL/kg within first 3 hours
- Saline or balanced crystalloids (e.g., Hartmann's/lactated Ringer's) are acceptable
- Hydroxyethyl starches and gelatins are not recommended
- Further fluid guided by dynamic markers (pulse pressure variation, stroke volume variation, POCUS) and lactate clearance
2. Vasopressors
(Harrison's, p. 8273)
| Agent | Role |
|---|---|
| Norepinephrine | First-line — alpha + beta adrenergic; titrate to MAP ≥ 65 mmHg |
| Vasopressin | Add-on to norepinephrine to reduce its dose (0.03–0.04 units/min) |
| Epinephrine | Second-line; added if MAP target not achieved |
| Dopamine | Avoid except in bradycardic patients at low risk of tachyarrhythmias |
| Dobutamine | For myocardial dysfunction / low CO despite adequate filling pressures |
3. Antimicrobials
- Administer within 1 hour of septic shock recognition — mortality increases with each hour of delay
- Empiric broad-spectrum coverage based on likely source, local resistance patterns, and immune status:
| Suspected Source | Empiric Regimen (example) |
|---|---|
| Community pneumonia | Beta-lactam + macrolide or fluoroquinolone |
| HAP/VAP | Antipseudomonal beta-lactam ± aminoglycoside |
| Urosepsis | 3rd-gen cephalosporin or piperacillin-tazobactam |
| Abdominal | Piperacillin-tazobactam or carbapenem + metronidazole |
| Unknown source | Broad gram-positive + gram-negative + anaerobe coverage |
| MRSA risk | Add vancomycin or linezolid |
| Immunocompromised | Add antifungal (e.g., echinocandin) |
- De-escalate once organism and sensitivities known
- Total duration typically 7–10 days (shorter if source controlled)
4. Source Control
- Drainage of abscesses, removal of infected devices/lines, surgical debridement
- Should be achieved as soon as medically feasible
5. Corticosteroids
- Consider hydrocortisone 200–300 mg/day IV (continuous infusion or intermittent dosing) if shock remains refractory despite adequate fluids and vasopressors
- Do not use dexamethasone or high-dose steroids
6. Supportive ICU Care
| Intervention | Target / Details |
|---|---|
| Mechanical ventilation (ARDS) | Lung-protective: TV 6 mL/kg IBW, plateau pressure < 30 cmH₂O |
| Glucose control | Target 7.8–10 mmol/L (140–180 mg/dL); avoid hypoglycemia |
| Renal replacement therapy | For AKI with fluid overload, severe acidosis, or hyperkalemia |
| DVT prophylaxis | LMWH (unless bleeding risk) |
| Stress ulcer prophylaxis | PPI or H₂ blocker in high-risk patients |
| Nutrition | Early enteral nutrition preferred; avoid prolonged NPO |
| Transfusion | RBC transfusion if Hb < 70 g/L (< 90 g/L in myocardial ischemia) |
Monitoring Endpoints
| Parameter | Target |
|---|---|
| MAP | ≥ 65 mmHg |
| Urine output | ≥ 0.5 mL/kg/hr |
| Lactate clearance | ≥ 10% reduction per 2 hours; normalize to < 2 mmol/L |
| CVP (if used) | 8–12 mmHg (less reliable alone) |
| ScvO₂ | ≥ 70% |
Complications
- ARDS — most common cause of respiratory failure
- AKI — may require renal replacement therapy
- DIC — coagulopathy, bleeding, microvascular thrombosis
- Septic cardiomyopathy — reversible myocardial dysfunction
- Critical illness neuropathy/myopathy — prolonged weakness
- Secondary infections — fungal, C. difficile
Prognosis
- Septic shock carries in-hospital mortality of 40–60%
- Mortality correlates with: number of organs failing, lactate level, delay to antibiotics, source control adequacy
- Survivors face increased risk of long-term cognitive impairment, physical disability, and re-hospitalization (post-sepsis syndrome)
Sources: Harrison's Principles of Internal Medicine, 21st Ed. (pp. 8257, 8273) | Surviving Sepsis Campaign International Guidelines
This is a shared conversation. Sign in to Orris to start your own chat.