The pulmonary artery catheter: When and why it should be used

Comparison of indirect calorimetry, the Fick method, and prediction equations in estimating the energy requirements of critically ill patients

BACKGROUND

Accurate measurement of resting energy expenditure (REE) is helpful in determining the energy needs of critically ill patients requiring nutritional support. Currently, the most accurate clinical tool used to measure REE is indirect calorimetry, which is expensive, requires trained personnel, and has significant error at higher inspired oxygen concentrations.

OBJECTIVE

The purpose of this study was to compare REE measured by indirect calorimetry with REE calculated by using the Fick method and prediction equations by Harris-Benedict, Ireton-Jones, Fusco, and Frankenfield.

DESIGN

REEs of 36 patients [12 men and 24 women, mean age 58+/-22 y and mean Acute Physiology and Chronic Health Evaluation II score 22+/-8] in a hospital intensive care unit and receiving mechanical ventilation and total parenteral nutrition (TPN) were measured for > or = 15 min by using indirect calorimetry and compared with REEs calculated from a mean of 2 sets of hemodynamic measurements taken during the metabolic testing period with an oximetric pulmonary artery catheter.

RESULTS

Mean REE by indirect calorimetry was 8381+/-1940 kJ/d and correlated poorly with the other methods tested (r = 0.057-0.154). This correlation did not improve after adjusting for changes in respiratory quotient (r2 = 0.28).

CONCLUSIONS

These data do not support previous findings showing a strong correlation between REE determined by the Fick method and other prediction equations and indirect calorimetry. In critically ill patients receiving TPN, indirect calorimetry, if available, remains the most appropriate clinical tool for accurate measurement of REE.

Physicians' judgments of the risks of cardiac procedures. Differences between cardiologists and other internists

OBJECTIVES

The authors compared judgments of the population risks of invasive cardiac procedures made by cardiologists and other internal medicine physicians. Our main hypotheses were that cardiologists' judgments would differ from those made by the other physicians and that cardiologists' judgments would be more accurate than those of other physicians.

METHODS

This was a cross-sectional survey of senior staff and physician-trainees at two teaching hospitals affiliated with a US medical school, Emergency Department physicians at a community hospital in the same metropolitan area, and senior staff and trainees at two teaching hospitals affiliated with a UK school. Judgments of the risks of severe morbidity and death due to Swan-Ganz catheterization, cardiac catheterization, percutaneous coronary angioplasty, and coronary artery bypass grafting were assessed.

RESULTS

Nineteen cardiologists judged the risks of severe morbidity due to all procedures and the risks of death due to all procedures except coronary artery bypass grafting to be significantly lower than did the 78 other internists. Cardiologists more frequently made accurate judgments of the rates of morbidity and death due to cardiac catheterization than did the other internists; other internists more frequently made accurate judgments for the rates of morbidity due to Swan-Ganz catheterization.

CONCLUSIONS

Disagreements about the risks of procedures may arise from a paucity of published data, or from an over-supply of confusing data.