Why I use the pulmonary artery catheter
Despite myocardial depression, most early deaths from sepsis are caused by profound vasodilatation, while some are caused by low cardiac output. Most late deaths are caused by multiple organ dysfunction. While fluid resuscitation and vasopressors, combined with definitive source control and antibiotics, may be effective, delayed improvement in organ dysfunction, positive fluid balance, shock and renal failure are associated with poor outcome. Indiscriminate vasopressor therapy may increase mortality rate.
Although observational studies reported increased mortality in association with the pulmonary artery catheter (PAC), these results have been refuted, as summarised in a recent meta-analysis. It is counterintuitive to expect an investigation alone to improve outcome; this requires an effective therapeutic intervention. Perhaps this accounts for the PAC-associated increase in mortality noted in low-risk intensive care unit patients, combined with the reduction in mortality in high-risk patients.
While alternative techniques of advanced haemodynamic monitoring are available, all have pros and cons. The PAC offers accurate cardiac output monitoring, measurement of central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP), a measure of right ventricular afterload (the pulmonary artery pressure) and mixed venous oxygen saturation, which is a more accurate measure of the adequacy of cardiac output than central venous oxygen saturation. The CVP and PAOP are important measures and can assist with fluid resuscitation. CVP is determined by venous return and right ventricular function, while PAOP is the major determinant of hydrostatic pulmonary oedema. Over half of cases of acute respiratory distress syndrome (ARDS) are due to sepsis, and right ventricular dysfunction in ARDS, measured as CVP > PAOP, is independently associated with death.
The PAC should be considered when particular patients present important therapeutic issues. However, this cannot replace a careful, clinically integrated approach.
Crit Care Resusc 2006; 8: 252–255
