TY - JOUR
T1 - Automated evaluation of functional residual capacity by oxygen washout
AU - Eichler, Wolfgang
AU - Schumacher, Jan
AU - Roth-Isigkeit, Angela
AU - Braun, Jörg
AU - Kuppe, Hermann
AU - Klotz, Karl Friedrich
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2002
Y1 - 2002
N2 - Objective. Measurement of functional residual capacity (FRC) is of considerable interest for monitoring ventilated patients in ICUs. However, the lack of instruments that can be used in the clinical setting has so far impeded the routine application of this measurement. It was the aim of our study to evaluate the accuracy and the reproducibility of a simplified oxygen washout technique (FRC[O2]). Materials and methods. For the evaluation of FRC[O2], gas flow, CO2 and O2 concentrations were determined by the flow probe of an ICU ventilator, a mainstream capnometer and O2 analyser. In 30 volunteers FRC[O2] as measured during spontaneous breathing was compared to: 1. Helium dilution technique (FRC[He], n = 21), 2. Body plethysmography (FRC[bp], n = 9). In n = 7 male patients FRC[O2] was repeatedly evaluated during mechanical ventilation and compared to the preoperative FRC[bp]. Results. FRC[O2] corresponded well with FRC[He] (range: 1.9 to 6.0 l, bias of FRC[O2]: 0.53 l (95% CI 0.24 l to 0.82 l)) and FRC[bp] (range: 2.1 to 4.3 l, bias of FRC[O2] 0.03 l (95% CI -0.30 l to 0.37 l)). The mean of the repeated FRC[O2]-measurements (basic range: 1.3 to 3.6 l) during mechanical ventilation with unchanged ventilator settings stayed unchanged. The within subject-between error ranged from 0.1 to 0.4 l (mean = 0.23 l). Mean FRC[O2] during mechanical ventilation decreased to 66.6 percent of the preoperative mean FRC[bp]. Conclusions. The automated oxygen washout technique is a simple method to measure FRC in the ICU patient.
AB - Objective. Measurement of functional residual capacity (FRC) is of considerable interest for monitoring ventilated patients in ICUs. However, the lack of instruments that can be used in the clinical setting has so far impeded the routine application of this measurement. It was the aim of our study to evaluate the accuracy and the reproducibility of a simplified oxygen washout technique (FRC[O2]). Materials and methods. For the evaluation of FRC[O2], gas flow, CO2 and O2 concentrations were determined by the flow probe of an ICU ventilator, a mainstream capnometer and O2 analyser. In 30 volunteers FRC[O2] as measured during spontaneous breathing was compared to: 1. Helium dilution technique (FRC[He], n = 21), 2. Body plethysmography (FRC[bp], n = 9). In n = 7 male patients FRC[O2] was repeatedly evaluated during mechanical ventilation and compared to the preoperative FRC[bp]. Results. FRC[O2] corresponded well with FRC[He] (range: 1.9 to 6.0 l, bias of FRC[O2]: 0.53 l (95% CI 0.24 l to 0.82 l)) and FRC[bp] (range: 2.1 to 4.3 l, bias of FRC[O2] 0.03 l (95% CI -0.30 l to 0.37 l)). The mean of the repeated FRC[O2]-measurements (basic range: 1.3 to 3.6 l) during mechanical ventilation with unchanged ventilator settings stayed unchanged. The within subject-between error ranged from 0.1 to 0.4 l (mean = 0.23 l). Mean FRC[O2] during mechanical ventilation decreased to 66.6 percent of the preoperative mean FRC[bp]. Conclusions. The automated oxygen washout technique is a simple method to measure FRC in the ICU patient.
UR - http://www.scopus.com/inward/record.url?scp=0036430061&partnerID=8YFLogxK
U2 - 10.1023/A:1020777912363
DO - 10.1023/A:1020777912363
M3 - Journal articles
C2 - 12455736
AN - SCOPUS:0036430061
SN - 1387-1307
VL - 17
SP - 195
EP - 201
JO - Journal of Clinical Monitoring and Computing
JF - Journal of Clinical Monitoring and Computing
IS - 3-4
ER -