This topic has never come up in the CICM fellowship exam. Likely, it is reserved for the primaries.
Consequences of Metabolic Acidosis
Respiratory consequences:
- Increased respiratory stimulus
- Increased work of breathing
- Right shift of the oxyhaemoglobin dissociation curve (i.e. a decreased affinity of haemoglobin for oxygen)
Cardiovascular consequences:
- Decreased cardiac output
- Increased propensity to arrhythmias
- Decreased systemic vascular tone and arterial vasodilation
- Decreased responsiveness to catecholamines
- Pulmonary vasoconstricition
Neurological consequences:
- Cerebral vasodilation, thus increased intracranial pressure
Electrolyte changes
- Hyperkalemia
- Hypercalcemia
Effects on renal function and fluid balance
- Increased renal ammonia production
- Increased renal tubular ammonia secretion
- Thus, increased renal oxygen demand
- Diuresis (eg. due to osmotic effect of "gap" anions)
Gastrointestinal consequences
- Decreased stomach emptying
- Nausea and vomiting
- Decreased splanchnic perfusion
Haematological consequences
- Coagulopathy (due to impaired clotting factor function) -
- Impaired platelet aggregation (due to effects of hyperchloraemia)
- (More on this in the chapter on the haemostatic resuscitation of massive haemorrhage in trauma)
References
Kraut, Jeffrey A., and Nicolaos E. Madias. "Metabolic acidosis: pathophysiology, diagnosis and management." Nature Reviews Nephrology 6.5 (2010): 274-285.
Fencl, Vladimir, et al. "Diagnosis of metabolic acid–base disturbances in critically ill patients." American journal of respiratory and critical care medicine162.6 (2000): 2246-2251.
Moviat, M. A. M., F. M. P. Van Haren, and J. G. Van Der Hoeven. "Conventional or physicochemical approach in intensive care unit patients with metabolic acidosis." Critical Care 7.3 (2003): R41.
Park, M., et al. "Clinical utility of standard base excess in the diagnosis and interpretation of metabolic acidosis in critically ill patients." Brazilian Journal of Medical and Biological Research 41.3 (2008): 241-249.
Handy, J. M., and N. Soni. "Physiological effects of hyperchloraemia and acidosis." British journal of anaesthesia 101.2 (2008): 141-150.