Modular indirect calorimeter suitable for long-term measurements in multipatient intensive care units.
OBJECTIVE
The construction of an indirect calorimeter capable of long-term automated sequential monitoring of multiple patients in adult and pediatric ICUs.


METHODS
A prototype system utilizing modular engineering principles, including central respiratory mass spectrometer; validation by organic solvent combustion and nitrogen dilution methods, and Tissot spirometer.


METHODS
Surgical and pediatric ICUs in a tertiary care university hospital.


RESULTS
When expired minute volume was measured over a range of 4 to 28 L in six intubated patients, expired minute volume measured by the prototype system demonstrated a correlation coefficient of .998 compared with simultaneous expired minute volume measured by a Tissot spirometer. Organic solvent combustion demonstrated a maximum error of 3.8% for oxygen consumption (VO2) and an average error of 1.73 +/- 1.25% (SEM). The maximum error for the respiratory quotient was 3.0%, with an average error of 1.75 +/- 1.07%. VO2 (predicted) vs. VO2 (measured) demonstrated a correlation coefficient of .997. Validation with the nitrogen dilution method over a range of FIO2 from 0.21 to 0.60 demonstrated a maximum error of 7.9%, with an average error of -1.72 +/- 1.1% (n = 51).


CONCLUSIONS
Indirect calorimetry by means of a shared system for measurements in multiple patients in ICUs is feasible and cost effective utilizing modular principles and a centralized respiratory gas analyzer.
Steinhorn
D M
DM
Pediatric Critical Care, University of Minnesota Hospital and Clinic, Minneapolis.
Rozenberg
A L
AL
Boyle
M J
MJ
Abrams
J H
JH
McComb
R C
RC
Gilmour
I
I
Cerra
F B
FB
D000328:Adult; D001784:Blood Gas Analysis / Q000191:economics / Q000295:instrumentation / Q000379:methods; D002138:Calibration; D002153:Calorimetry, Indirect / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D002648:Child; D003362:Cost-Benefit Analysis; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D006801:Humans; D007362:Intensive Care Units; D008838:Microcomputers; D008991:Monitoring, Physiologic / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D015596:Nutrition Assessment; D010101:Oxygen Consumption; D015203:Reproducibility of Results; D012997:Solvents; D013147:Spirometry / Q000191:economics / Q000295:instrumentation* / Q000379:methods
D012997:Solvents