There is now good evidence that pulmonary artery catheters (formerly known as Swan-Ganz catheters) do not improve survival in critically ill patients in intensive care. The evidence has already filtered into practice, and doctors use them less and less, according to analysis of routine hospital data from the US. Between 1993 and 2004, the use of these catheters for medical inpatients fell by 65%, from 5.66 to 1.99 per 1000 admissions (risk ratio 0.35, 95% CI 0.29 to 0.42). The researchers found a similar trend in surgical patients, and in both teaching and non-teaching hospitals. The decline was most pronounced (81%) for patients with heart attack.
So doctors are using fewer pulmonary artery catheters, but are they using other less invasive ways of measuring cardiac output instead? This would be a shame, says a linked editorial (p 458). These new technologies are untested and there's a chance that the whole cycle could start again. We still don't know if measuring cardiac output by any method improves outcomes for patients, however much doctors enjoy doing it. For now, they should treat new methods with healthy scepticism and remember that more numbers to manipulate does not necessarily translate into better management or longer survival.