Hypotension Diagnosis and Treatment

Hypotension: An Approach to Diagnosis

• listing a differential diagnosis for the causes of hypotension could exceed 20 possibilities
• in a situation requiring urgent action, it is important to arrive at a likely diagnosis rapidly
• being aware of recent events during surgery, and reviewing the clinical condition of the patient (vitals, etc.)  allows a focused search for its cause, and rapid, specific treatment
• decide whether the problem is due to HR, preload, afterload, or contractility, based on the clinical information available

Hypotension Determinants of Blood Pressure

• BP = Cardiac Output x Systemic Vascular Resistance
• Cardiac Output = Heart Rate x Stroke Volume
• Stroke Volume depends on Afterload, Preload and Contractility

Evaluation of Hypotension

 Observe Vital Signs:

• HR
• EKG re: ischemia or dysrhythmias
• Systolic and Diastolic Pressures +/- Waveform
• SpO2
• ETCO2 Tracing
• Airway Pressure
• CVP, PAP, PAOP, CO, if available

Observe Surgical Field:

• hemorrhage?
•  great vessel compression?
• risk of embolization?
• extensive third space losses?

Consider Other Possible Causative Factors:

• central neuraxial blockade
• trauma - multiple considerations
• recent drug administration; +/- allergy Hx
• sepsis
•  hypoxia
• myocardial dysfunction
• anesthetic depth

There is a simple algorithm "VOCAL", that is helpful to rule out common causes of perioperative cardiorespiratory dysfunction.

It involves 2 steps:

1. a check of
• Ventilation
• Oxygenation
• Cardiac Activity
• Anesthetic Level
2. and running through a system-by-system checklist: List ABCDEFGHI