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Perioperative oxygen fraction - effect on surgical site infection and pulmonary complications after abdominal surgery: a randomized clinical trial. Rationale and design of the PROXI-Trial.

Meyhoff CS, Wetterslev J, Jorgensen LN, Henneberg SW, Simonsen I, Pulawska T, Walker LR, Skovgaard N, Heltø K, Gocht-Jensen P, Carlsson PS, Rask H, Karim S, Carlsen CG, Jensen FS, Rasmussen LS, PROXI Trial Gro - Trials (2008)

Bottom Line: A high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension.The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit.The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. meyhoff@rh.dk

ABSTRACT

Background: A high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension. Two trials have shown that a high perioperative inspiratory oxygen fraction (FiO(2) = 0.80) significantly reduced risk of surgical site infections after elective colorectal surgery, but a third trial was stopped early because the frequency of surgical site infections was more than doubled in the group receiving FiO(2) = 0.80. It has not been settled if a high inspiratory oxygen fraction increases the risk of pulmonary complications, such as atelectasis, pneumonia and respiratory failure. The aim of our trial is to assess the potential benefits and harms of a high perioperative oxygen fraction in patients undergoing abdominal surgery.

Methods and design: The PROXI-Trial is a randomized, patient- and assessor blinded trial of perioperative supplemental oxygen in 1400 patients undergoing acute or elective laparotomy in 14 Danish hospitals. Patients are randomized to receive either 80% oxygen (FiO(2) = 0.80) or 30% oxygen (FiO(2) = 0.30) during surgery and for the first 2 postoperative hours. The primary outcome is surgical site infection within 14 days. The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit. The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.

Discussion: This trial assesses benefits and harms of a high inspiratory oxygen fraction, and the trial may be generalizable to a general surgical population undergoing laparotomy.

Trial registration: ClinicalTrials.gov identifier: NCT00364741.

No MeSH data available.


Related in: MedlinePlus

Trial sequential analysis of all trials irrespective of adjuvant inhaled gases. The effect of 80% oxygen vs. 30% oxygen on surgical site infections calculated in cumulative meta-analysis of all trials irrespective adjuvant inhaled gases (the trials by Greif [13], Pryor [15], Belda [12], Mayzler [14] and Myles [42]). The low-bias heterogeneity adjusted information size (LBHIS) is 4500 based on a relative risk reduction (RRR) suggested by the low-bias trials of 33% and a meta-analytic estimate of the frequency of surgical site infection in the control group (30% oxygen) on 14% with a type I error risk of 5% and a power of 80%. No crossing of the trial sequential monitoring boundary at any time despite P < 0.05 after the first trial [13]. The gap of information to reject an intervention effect of 33% relative risk reduction is approximately 1500 patients.
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Figure 4: Trial sequential analysis of all trials irrespective of adjuvant inhaled gases. The effect of 80% oxygen vs. 30% oxygen on surgical site infections calculated in cumulative meta-analysis of all trials irrespective adjuvant inhaled gases (the trials by Greif [13], Pryor [15], Belda [12], Mayzler [14] and Myles [42]). The low-bias heterogeneity adjusted information size (LBHIS) is 4500 based on a relative risk reduction (RRR) suggested by the low-bias trials of 33% and a meta-analytic estimate of the frequency of surgical site infection in the control group (30% oxygen) on 14% with a type I error risk of 5% and a power of 80%. No crossing of the trial sequential monitoring boundary at any time despite P < 0.05 after the first trial [13]. The gap of information to reject an intervention effect of 33% relative risk reduction is approximately 1500 patients.

Mentions: Some additional trials suggest that a high oxygen fraction in the perioperative period is beneficial. Firstly, patients undergoing nitrous oxide-free anaesthesia with 80% oxygen had fewer wound infections than patients receiving nitrous oxide-based (70% N2O, 30% oxygen) anaesthesia [42]. The higher oxygen concentration could have contributed significantly to this difference, because nitrous oxide may not be a risk factor for wound infections [43]. Secondly, another large trial investigating treatment of hypoxia via continuous positive airway pressure in the postoperative period also demonstrated a reduction in wound infections [44]. However, even if the nitrous-oxide trial [42] is incorporated in the trial sequential analysis, there is still a gap of information of approximately 1500 patients to reject an intervention effect of 33% relative risk reduction (Fig. 4).


Perioperative oxygen fraction - effect on surgical site infection and pulmonary complications after abdominal surgery: a randomized clinical trial. Rationale and design of the PROXI-Trial.

Meyhoff CS, Wetterslev J, Jorgensen LN, Henneberg SW, Simonsen I, Pulawska T, Walker LR, Skovgaard N, Heltø K, Gocht-Jensen P, Carlsson PS, Rask H, Karim S, Carlsen CG, Jensen FS, Rasmussen LS, PROXI Trial Gro - Trials (2008)

Trial sequential analysis of all trials irrespective of adjuvant inhaled gases. The effect of 80% oxygen vs. 30% oxygen on surgical site infections calculated in cumulative meta-analysis of all trials irrespective adjuvant inhaled gases (the trials by Greif [13], Pryor [15], Belda [12], Mayzler [14] and Myles [42]). The low-bias heterogeneity adjusted information size (LBHIS) is 4500 based on a relative risk reduction (RRR) suggested by the low-bias trials of 33% and a meta-analytic estimate of the frequency of surgical site infection in the control group (30% oxygen) on 14% with a type I error risk of 5% and a power of 80%. No crossing of the trial sequential monitoring boundary at any time despite P < 0.05 after the first trial [13]. The gap of information to reject an intervention effect of 33% relative risk reduction is approximately 1500 patients.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2600782&req=5

Figure 4: Trial sequential analysis of all trials irrespective of adjuvant inhaled gases. The effect of 80% oxygen vs. 30% oxygen on surgical site infections calculated in cumulative meta-analysis of all trials irrespective adjuvant inhaled gases (the trials by Greif [13], Pryor [15], Belda [12], Mayzler [14] and Myles [42]). The low-bias heterogeneity adjusted information size (LBHIS) is 4500 based on a relative risk reduction (RRR) suggested by the low-bias trials of 33% and a meta-analytic estimate of the frequency of surgical site infection in the control group (30% oxygen) on 14% with a type I error risk of 5% and a power of 80%. No crossing of the trial sequential monitoring boundary at any time despite P < 0.05 after the first trial [13]. The gap of information to reject an intervention effect of 33% relative risk reduction is approximately 1500 patients.
Mentions: Some additional trials suggest that a high oxygen fraction in the perioperative period is beneficial. Firstly, patients undergoing nitrous oxide-free anaesthesia with 80% oxygen had fewer wound infections than patients receiving nitrous oxide-based (70% N2O, 30% oxygen) anaesthesia [42]. The higher oxygen concentration could have contributed significantly to this difference, because nitrous oxide may not be a risk factor for wound infections [43]. Secondly, another large trial investigating treatment of hypoxia via continuous positive airway pressure in the postoperative period also demonstrated a reduction in wound infections [44]. However, even if the nitrous-oxide trial [42] is incorporated in the trial sequential analysis, there is still a gap of information of approximately 1500 patients to reject an intervention effect of 33% relative risk reduction (Fig. 4).

Bottom Line: A high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension.The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit.The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. meyhoff@rh.dk

ABSTRACT

Background: A high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension. Two trials have shown that a high perioperative inspiratory oxygen fraction (FiO(2) = 0.80) significantly reduced risk of surgical site infections after elective colorectal surgery, but a third trial was stopped early because the frequency of surgical site infections was more than doubled in the group receiving FiO(2) = 0.80. It has not been settled if a high inspiratory oxygen fraction increases the risk of pulmonary complications, such as atelectasis, pneumonia and respiratory failure. The aim of our trial is to assess the potential benefits and harms of a high perioperative oxygen fraction in patients undergoing abdominal surgery.

Methods and design: The PROXI-Trial is a randomized, patient- and assessor blinded trial of perioperative supplemental oxygen in 1400 patients undergoing acute or elective laparotomy in 14 Danish hospitals. Patients are randomized to receive either 80% oxygen (FiO(2) = 0.80) or 30% oxygen (FiO(2) = 0.30) during surgery and for the first 2 postoperative hours. The primary outcome is surgical site infection within 14 days. The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit. The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.

Discussion: This trial assesses benefits and harms of a high inspiratory oxygen fraction, and the trial may be generalizable to a general surgical population undergoing laparotomy.

Trial registration: ClinicalTrials.gov identifier: NCT00364741.

No MeSH data available.


Related in: MedlinePlus