Please use this identifier to cite or link to this item: http://ahro.austin.org.au/austinjspui/handle/1/22662
Title: Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery.
Authors: Wong, Clarence;Churilov, Leonid;Cowie, Dean A;Tan, Chong O;Hu, Raymond;Tremewen, David;Pearce, Brett;Pillai, Param;Karalapillai, Dharshi;Bellomo, Rinaldo;Weinberg, Laurence
Affiliation: Department of Surgery, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
The Department of Medicine, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
Issue Date: 16-Feb-2020
EDate: 2020-02-16
Citation: BMJ open 2020; 10(2): e029159
Abstract: The effects of hypercapnia on regional cerebral oxygen saturation (rSO2) during surgery are unclear. We conducted a randomised controlled trial to investigate the relationship between mild hypercapnia and rSO2. We hypothesised that, compared with targeted normocapnia (TN), targeted mild hypercapnia (TMH) during major surgery would increase rSO2. A prospective, randomised, controlled trial in adult participants undergoing elective major surgery. A single tertiary centre in Heidelberg, Victoria, Australia. 40 participants were randomised to either a TMH or TN group (20 to each). TMH (partial pressure of carbon dioxide in arterial blood, PaCO2, 45-55 mm Hg) or TN (PaCO2 35-40 mm Hg) was delivered via controlled ventilation throughout surgery. The primary endpoint was the absolute difference between the two groups in percentage change in rSO2 from baseline to completion of surgery. Secondary endpoints included intraoperative pH, bicarbonate concentration, base excess, serum potassium concentration, incidence of postoperative delirium and length of stay (LOS) in hospital. The absolute difference between the two groups in percentage change in rSO2 from the baseline to the completion of surgery was 19.0% higher in both hemispheres with TMH (p<0.001). On both sides, the percentage change in rSO2 was greater in the TMH group than the TN group throughout the duration of surgery. The difference between the groups became more noticeable over time. Furthermore, postoperative delirium was higher in the TN group (risk difference 0.3, 95% CI 0.1 to 0.5, p=0.02). LOS was similar between groups (5 days vs 5 days; p=0.99). TMH was associated with a stable increase in rSO2 from the baseline, while TN was associated with a decrease in rSO2 in both hemispheres in patients undergoing major surgery. This resulted in a clear separation of percentage change in rSO2 from the baseline between TMH and TN over time. Our findings provide the rationale for larger studies on TMH during surgery. The Australian New Zealand Clinical Trials Registry (ACTRN12616000320459).
URI: http://ahro.austin.org.au/austinjspui/handle/1/22662
DOI: 10.1136/bmjopen-2019-029159
ORCID: 0000-0002-5422-8145
0000-0002-9807-6606
0000-0002-1650-8939
0000-0001-7403-7680
PubMed URL: 32066598
Type: Journal Article
Subjects: delirium
hypercapnia
oximetry
respiration, artificial
spectroscopy, near infrared
Appears in Collections:Journal articles

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