Postoperative Pulmonary Atelectasis, Surgery
Conditions
Keywords
Continuous Positive Airway Pressure, Postoperative Complications, Respiratory Insufficiency, Colorectal Surgery
Brief summary
The purpose of this study is to determine whether prophylactic nasal continuous positive airway pressure (nCPAP) in the post-anaesthesia care unit (PACU) improves post-operative pulmonary function following elective bowel surgery. The investigators hypothesize that one hour of nCPAP in the PACU will result in a higher partial pressure of arterial oxygen (PaO2) when compared to the standard treatment of low flow oxygen applied by face mask.
Detailed description
Post-operative pulmonary complications, such as hypoxemia, pneumonia and respiratory failure, occur in 5-10% of patients following abdominal surgery. These post-operative pulmonary complications result in increased morbidity, mortality, ICU admission, length of hospital stay and resource use. CPAP has shown to be an effective treatment for hypoxemia following abdominal surgery. It decreases atelectasis formation the risk of pneumonia. Application of nCPAP to treat hypoxemic respiratory failure following thoraco-abdominal surgery has shown to decrease endotracheal intubation. Nasal CPAP has shown to be effective prophylaxis following elective cardiac and thoraco-abdominal aortic surgery. It reduces the incidence of hypoxemia, pneumonia, re-intubation and re-admission to the ICU. It has also shown to decrease the length of hospital stay. The use of nCPAP immediately post-operatively in the PACU following abdominal surgery has not been evaluated. Nasal CPAP is better tolerated than full face mask CPAP. It allows for effective clearance of respiratory secretions, improved communication and decreases claustrophobic sensation. The PACU is a transition period from general anaesthesia into the post-operative recovery phase. During this time, residual anaesthetic causes decreased level of consciousness and sub-optimal respiratory effort. Reversal agent for neuromuscular blockade has often not reached its peak effect. Inadequate pain control may further decrease respiratory effort. This transition period may be when maximal atelectasis of alveolar lung units occurs. This time period may be optimal for the application of nCPAP for prophylaxis against hypoxemia. It may improve post-operative pulmonary function which could decrease post-operative morbidity, mortality, length of hospital stay and resource use.
Interventions
DEVICEnCPAP
The experimental group will receive nasal CPAP at 10cmH20 for one hour in the Post Anesthetic Care Unit.
DEVICELow Flow Oxygen
The control group will receive standard therapy of low flow oxygen via simple mask at 8 litres per minute.
Sponsors
Royal University Hospital Foundation
University of Saskatchewan
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Patients scheduled to undergo elective laparotomy for bowel surgery
Exclusion criteria
* age \< 18 years * postoperative admission to the intensive care unit * a history of allergy/intolerance to Ametop
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Alveolar - Arterial Gradient | 1 hour following admission to PACU | The alveolar - arterial gradient is the difference between the partial pressure of alveolar oxygen and the partial pressure of arterial oxygen |
Secondary
| Measure | Time frame |
|---|---|
| Number of Participants Requiring Reintubation | Up to 2 weeks |
| Number of Participants Requiring Admission to ICU | Up to 2 weeks |
| Length of Stay in Hospital | Up to 2 weeks |
Participant flow
Recruitment details
Recruitment began 4 April 2011 and ended 29 April 2012. The target enrollment was 40. 40 patients were enrolled in the study.
Participants by arm
| Arm | Count |
|---|---|
| nCPAP The experimental group will receive nasal CPAP at 10cmH20 for one hour in the Post Anesthetic Care Unit. | 20 |
| Low Flow Oxygen The control group will receive standard therapy of low flow oxygen via simple mask at 8 litres per minute. | 20 |
| Total | 40 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Required alternate treatment | 0 | 1 |
| Overall Study | Withdrawal by Subject | 2 | 0 |
Baseline characteristics
| Characteristic | nCPAP | Low Flow Oxygen | Total |
|---|---|---|---|
| Age, Continuous | 63 years STANDARD_DEVIATION 12 | 61 years STANDARD_DEVIATION 11.4 | 62 years STANDARD_DEVIATION 11.6 |
| Region of Enrollment Canada | 20 participants | 20 participants | 40 participants |
| Sex: Female, Male Female | 6 Participants | 13 Participants | 19 Participants |
| Sex: Female, Male Male | 14 Participants | 7 Participants | 21 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 18 | 0 / 19 |
| other Total, other adverse events | 0 / 18 | 0 / 19 |
| serious Total, serious adverse events | 0 / 18 | 0 / 19 |
Outcome results
Primary
Alveolar - Arterial Gradient
The alveolar - arterial gradient is the difference between the partial pressure of alveolar oxygen and the partial pressure of arterial oxygen
Time frame: 1 hour following admission to PACU
Population: From the literature, a sample size of 19 subjects per group is required for a power \>0.9 and alpha \<0.05 assuming a normalised difference in A-a gradient between groups of 0.33 and a Standard Deviation (SD) of 0.33
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| nCPAP | Alveolar - Arterial Gradient | 70.6 torr | Standard Deviation 28.3 |
| Low Flow Oxygen | Alveolar - Arterial Gradient | 134 torr | Standard Deviation 72.6 |
Secondary
Length of Stay in Hospital
Time frame: Up to 2 weeks
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| nCPAP | Length of Stay in Hospital | 10 days | Standard Deviation 7.4 |
| Low Flow Oxygen | Length of Stay in Hospital | 10.9 days | Standard Deviation 6.7 |
Secondary
Number of Participants Requiring Admission to ICU
Time frame: Up to 2 weeks
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| nCPAP | Number of Participants Requiring Admission to ICU | 0 participants |
| Low Flow Oxygen | Number of Participants Requiring Admission to ICU | 0 participants |
Secondary
Number of Participants Requiring Reintubation
Time frame: Up to 2 weeks
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| nCPAP | Number of Participants Requiring Reintubation | 0 participants |
| Low Flow Oxygen | Number of Participants Requiring Reintubation | 0 participants |