In assessing a critically ill patient, what primary indicator suggests danger of decompensation?

Low serum HCO3- levels are a primary indicator that suggests the danger of decompensation in a critically ill patient. Bicarbonate (HCO3-) is a crucial component of the body's buffering system, which helps maintain acid-base homeostasis. When HCO3- levels are low, it indicates that the body may be experiencing metabolic acidosis, a condition that can arise from various underlying issues such as severe infection, renal failure, or shock.

In critically ill patients, a decrease in bicarbonate levels can lead to an accumulation of acids in the blood, further impairing cellular function and potentially progressing to respiratory distress and multi-organ failure. Monitoring bicarbonate levels provides vital information about the patient's metabolic state and can help guide the management of their condition to prevent further decompensation.

High blood pressure might be observed in certain stress or hypertensive states, but it does not necessarily indicate an immediate threat of decompensation. Cyanosis signals reduced oxygenation and can be more indicative of respiratory failure rather than a direct metabolic issue. High oxygen saturation generally suggests adequate oxygen delivery, which is a positive sign, contrasting with the potential danger highlighted by low HCO3- levels.