Helium-oxygen reduces the production of carbon dioxide during weaning from mechanical ventilation.
BACKGROUND
Prolonged weaning from mechanical ventilation has a major impact on ICU bed occupancy and patient outcome, and has significant cost implications.There is evidence in patients around the period of extubation that helium-oxygen leads to a reduction in the work of breathing. Therefore breathing helium-oxygen during weaning may be a useful adjunct to facilitate weaning. We hypothesised that breathing helium-oxygen would reduce carbon dioxide production during the weaning phase of mechanical ventilation.


METHODS
We performed a prospective randomised controlled single blinded cross-over trial on 19 adult intensive care patients without significant airways disease who fulfilled criteria for weaning with CPAP. Patients were randomised to helium-oxygen and air-oxygen delivered during a 2 hour period of CPAP ventilation. Carbon dioxide production (VCO2) was measured using a near patient main stream infrared carbon dioxide sensor and fixed orifice pneumotachograph.


RESULTS
Compared to air-oxygen, helium-oxygen significantly decreased VCO2 production at the end of the 2 hour period of CPAP ventilation; there was a mean difference in CO2 production of 48.9 ml/min (95% CI 18.7-79.2 p = 0.003) between the groups. There were no significant differences in other respiratory and haemodynamic parameters.


CONCLUSIONS
This study shows that breathing a helium-oxygen mixture during weaning reduces carbon dioxide production. This physiological study supports the need for a clinical trial of helium-oxygen mixture during the weaning phase of mechanical ventilation with duration of weaning as the primary outcome.


BACKGROUND
ISRCTN56470948.
Flynn
Gordon
G
Intensive Care Unit, Royal London Hospital, Whitechapel, London, E1 1BB, UK. Gordon.Flynn@sesiahs.health.nsw.gov.au
Mandersloot
Gerlinde
G
Healy
Marie
M
Saville
Mark
M
McAuley
Daniel F
DF
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D018592:Cross-Over Studies; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods; D016037:Single-Blind Method; D015300:Ventilator Weaning / Q000379:methods*; D055815:Young Adult
D002245:Carbon Dioxide; D006371:Helium; D010100:Oxygen
Chest. 2001 Dec;120(6 Suppl):375S-95S
11742959
Anaesthesia. 2007 Jan;62(1):34-42
17156225
Intensive Care Med. 2005 Nov;31(11):1501-7
16172846
Chest. 1995 Jul;108(1):196-202
7606958
Respir Care. 2004 Jul;49(7):830-6
15222913
Respir Physiol. 1995 Jan;99(1):183-90
7740207
Am J Respir Crit Care Med. 2001 Aug 15;164(4):633-7
11520728
Crit Care Med. 2003 May;31(5):1415-20
12771612
Chest. 1994 Oct;106(4):1188-93
7924494
J Thorac Cardiovasc Surg. 1976 Jul;72(1):119-22
778498
N Engl J Med. 1995 Feb 9;332(6):345-50
7823995
Intensive Care Med. 2003 Oct;29(10):1666-70
12897990
J Appl Physiol. 1949 Dec;2(6):300-6
15403654
Anaesthesia. 2005 Jan;60(1):72-6
15601276
Am J Respir Crit Care Med. 1999 Jul;160(1):22-32
10390375
Crit Care Med. 1996 Jan;24(1):96-102
8565546