1995 OPEN FORUM Abstracts
MUSCULAR ACTIVITY CONTRIBUTES TO THE INCREASE IN OXYGEN DEMAND DURING CHEST PHYSIOTHERAPY
M Kemper, BA, CRTT, C Itable CCRN, MSN, K Horiuchi MD, C Weissman MD, Columbia Presbyterian Medical Center, Departments of Medicine, Anethesiology and Nursing, New York, NY
Introduction: Increases in O2 consumption (VO2) during chest physiotherapy (CPT) may be due to both catecholamine secretion and muscle activity. Our study examined the effects of muscle relaxants on the physiologic response to CPT.
Methods: Ten postop ventilator dependent (IMV mode), SICU pts were studied. All pts had peripheral and pulmonary artery catheters. Thye were ventilated with the PB 7200 (Carlsbad CA) and metabolically monitored with a PB 7250 metabolic monitor. Pts underwent two CPT sessions, before one a Vecuronium 0.07 mg/kg and Midazolam 0.15 mg/kg combination was administered and berfore the other a placebo plus Midazolam.0.15 mg/kg. The order was determined randomly. There were rest periods before and after each CPT session. Simultaneous blood samples from both catheters were collected at the end of each rest period and CPT session.
(ml/min) Drug 223+/-45 235+/-65+217+/-51
DO_2Placebo 1073+/-2431145+/-244 872+/-182
(ml/min) Drug 872+/-182 1052+/-262* 931+/-295
SvO_2 Placebo 75.9+/-5.1 68.6+/-5.7*72.6+/-5.6
mmHgDrug 72.6+/-5.6 76.2+/-3.2*+74.5+/-4.8
VCO_2 Placebo 187+/-30247+/-43* 184+/-36
ml/min Drug 184+/-36 164+/-26+ 172+/-31
L/min Drug 10+/-28+/-1 8+/-1
P_aO_2 Placebo 139+/-36116+/-25* 136+/29
mmHgDrug 136+/-29 128+/-26+ 132+/-31
f Placebo 13+/-518+/-8+ 14+/-6
(bpm) Drug 14+/-611+/-211+/-2
SBP Placebo 129+/-21 150+/-124* 122+/-24
(mmhg) Drug 122+/-24 155+/-39126+/-24
HRPlacebo 94+/-15 103+/-2191+/-16
(bpm) Drug 91+/-16 96+/-17 92+/-20
*Different than rest(p < 0.05) + Different when drug and placebo compared (p < 0.05)
Conclusion: The increase in VO2 and VCO2 caused by CPTwas attenuated by the paralyzing agent, blood pressure was unaffected. The drug prevented an increase in VE but there was no greater increase in P_aCO2 than with placebo since the VCO2 increase was suppressed. Muscle activity contributes substantially to the VO2 increase during CPT. Sympathetie output was unaffected as the SBP increase was not attenuated.