You are here

  • Home
  • Archive
  • Volume 10, Issue 2
  • Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery

Article Text

Article menu

Download PDFPDF

XML
Anaesthesia
Original research
Randomised controlled trial to investigate the relationship between mild hypercapnia and cerebral oxygen saturation in patients undergoing major surgery
  1. Clarence Wong1,
  2. Leonid Churilov2,
  3. Dean Cowie1,
  4. Chong Oon Tan1,
  5. Raymond Hu1,
  6. David Tremewen1,
  7. Brett Pearce1,
  8. Param Pillai1,
  9. Dharshi Karalapillai1,
  10. Rinaldo Bellomo3,
  11. Laurence Weinberg1,4
  1. 1 Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
  2. 2 The Department of Medicine, Austin Health, The Univesity of Melbourne, Heidelberg, Victoria, Australia
  3. 3 Department of Intensive Care, Austin Hospital, Heidelberg, Victoria, Australia
  4. 4 Department of Surgery, Austin Health, The University of Melbourne, Heidelberg, Victoria, Australia
  1. Correspondence to A/Prof Laurence Weinberg; laurence.weinberg{at}austin.org.au

Abstract

Objectives 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.

Design A prospective, randomised, controlled trial in adult participants undergoing elective major surgery.

Setting A single tertiary centre in Heidelberg, Victoria, Australia.

Participants 40 participants were randomised to either a TMH or TN group (20 to each).

Interventions 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.

Primary and secondary outcome measures 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.

Results 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).

Conclusion 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.

Trial registration number The Australian New Zealand Clinical Trials Registry (ACTRN12616000320459).

  • delirium
  • hypercapnia
  • oximetry
  • respiration, artificial
  • spectroscopy, near infrared
http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjopen-2019-029159

Statistics from Altmetric.com

    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

    View Full Text

    Footnotes

    • Presented at Findings of this study were presented as a poster presentation at the PostGraduate Assembly in Anesthesiology held during 8–12 December 2018 at New York, USA.

    • Contributors CW and LC contributed to data collection, data analysis and manuscript write-up. DC contributed to patient recruitment, data collection and preparation of manuscript. COT, RH, DT, BP and PP contributed to patient recruitment and preparation of manuscript. DK contributed to data collection and preparation of manuscript. RB contributed to study design and preparation of manuscript. LW designed the study, contributed to patient recruitment, data collection, data analysis and preparation of manuscript.

    • Funding Masimo provided the oximetry sensors used for this trial. This study conception, design, trial management, data collection, data analysis, and the writing of the manuscript, have been executed completely independently of Masimo and any other external organisations. This work was supported by the Deparment of Anaesthesia Research Fund, Austin Hospital, Heidelberg, Victoria, Australia.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available upon reasonable request.