Hemodynamic Stability
Hemodynamic stability refers to the maintenance of adequate blood circulation and perfusion pressure to vital organs, particularly the brain, heart, and kidneys. It is a critical parameter during perioperative care, critical illness, and trauma resuscitation.
Key Parameters
Hemodynamic status is typically assessed by monitoring:
- Blood pressure (BP): systolic, diastolic, mean arterial pressure (MAP)
- Heart rate (HR) and rhythm
- Cardiac output (CO) and stroke volume (SV)
- Central venous pressure (CVP)
- Peripheral perfusion: capillary refill, skin temperature, lactate
- Urine output: indirect marker of renal perfusion
Definitions
- Stable: Adequate BP (MAP ≥ 65 mmHg), normal HR, good perfusion signs
- Unstable: Hypotension (MAP < 60–65 mmHg), tachycardia or bradycardia, signs of hypoperfusion (oliguria, confusion, mottling)
Causes of Instability
- Hypovolemia: hemorrhage, dehydration
- Cardiogenic: myocardial infarction, arrhythmias
- Distributive: sepsis, anaphylaxis
- Obstructive: tension pneumothorax, cardiac tamponade, pulmonary embolism
Clinical Importance
- Guides fluid therapy, vasopressor/inotrope use, and monitoring strategies
- Essential for safe anesthesia and surgical outcomes
- Unstable hemodynamics increase risk of organ failure, stroke, or death
Management Strategies
- Fluids: crystalloids, colloids, blood products
- Vasopressors: norepinephrine, phenylephrine, vasopressin
- Inotropes: dobutamine, epinephrine
- Monitoring: invasive BP, arterial line, echocardiography, advanced hemodynamic devices (e.g. PiCCO, FloTrac)
Example: Craniotomy and Hemodynamics
In neurosurgical patients:
- Sudden increases in BP may raise intracranial pressure (ICP)
- Scalp block or adequate analgesia helps maintain stability during craniotomy
- Hypotension should be avoided to preserve cerebral perfusion pressure (CPP = MAP - ICP)