Should hypotension or oxygen saturation below 92% be corrected first in a non-smoker?

From the Guidelines

In a medical emergency involving a non-smoker with both hypoxemia (O2 saturation below 92%) and hypotension (85 mmHg systolic), prioritize treating the hypotension first. This approach is based on the principle that circulation must be established before oxygenation can be effective, as inadequate blood pressure compromises tissue perfusion throughout the body, including the brain and heart 1. According to the BTS guideline for oxygen use in adults in healthcare and emergency settings, the recommended target saturation range for acutely ill patients not at risk of hypercapnic respiratory failure is 94–98% 1. However, in this scenario, addressing hypotension takes precedence over correcting oxygen saturation below 92%.

Begin with fluid resuscitation using crystalloids like normal saline or Ringer's lactate, administering 500-1000 mL as an initial bolus. While addressing the hypotension, provide supplemental oxygen via nasal cannula at 2-4 L/min or face mask at 5-10 L/min to help with the hypoxemia. If the patient remains hypotensive after initial fluid bolus, consider vasopressors such as norepinephrine (starting at 0.05-0.1 mcg/kg/min) or phenylephrine (starting at 100-180 mcg/min). Once blood pressure stabilizes to at least 90 mmHg systolic, you can focus more specifically on optimizing oxygenation if the patient remains hypoxemic.

Key considerations in managing these patients include:

• Maintaining the most upright posture possible to reduce oxygenation reduction in the supine position 1
• Monitoring for sudden reductions in oxygen saturation within the target saturation range, which may indicate an acute illness 1
• Adjusting oxygen therapy based on individual patient needs and risk factors for hypercapnic respiratory failure 1

From the Research

Addressing Hypotension and Low O2 Sats

• For a non-smoker with hypotension (systolic blood pressure of 85 mmHg) and low O2 sats (below 92%), the priority is to address the condition that poses the most immediate threat to the patient's health.
• Hypotension can lead to inadequate organ perfusion, which can result in organ failure if not addressed promptly 2, 3.
• Low O2 sats, on the other hand, can lead to hypoxia, which can also have serious consequences if not addressed promptly.
• However, according to the available evidence, hypotension is generally considered a more immediate threat to the patient's health than low O2 sats 2, 3.

Prioritizing Hypotension

• The studies suggest that hypotension should be addressed first, as it can lead to more severe consequences if not treated promptly 2, 3.
• Vasopressors such as norepinephrine are commonly used to treat hypotension in critically ill patients 2, 3.
• The goal of vasopressor therapy is to restore adequate blood pressure and perfusion to vital organs.

Oxygen Saturation Targets

• The target oxygen saturation range for adult patients without COPD or other conditions associated with chronic respiratory failure is 92-96% 4.
• This range is considered optimal for minimizing the risk of hypoxia while also avoiding the potential harms of excessive oxygen supplementation.
• However, in the context of hypotension, addressing the low blood pressure may take priority over correcting low O2 sats.