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. 2008 Sep 29;2008:2201.

Postoperative pulmonary infections

Michelle Conde 1,#, Valerie Lawrence 2,#
PMCID: PMC2907981  PMID: 19445796

Abstract

Introduction

Postoperative pulmonary infections are associated with cough, phlegm, shortness of breath, chest pain, temperature above 38°C, and pulse rate above 100 a minute. Up to half of people may have asymptomatic chest signs after surgery, and up to a quarter develop symptomatic disease. The main risk factor is the type of surgery, with higher risks associated with surgery to the chest, abdomen, and head and neck compared with other operations. Other risk factors include age over 50 years, chronic obstructive pulmonary disease (COPD), smoking, hypoalbuminaemia, and being functionally dependent.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to prevent postoperative pulmonary infections? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

Results

We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

Conclusions

In this systematic review we present information relating to the effectiveness and safety of the following interventions: advice to stop smoking preoperatively, anaesthesia, lung expansion techniques, and postoperative nasogastric decompression.

Key Points

Postoperative pulmonary infections are associated with cough, phlegm, shortness of breath, chest pain, temperature above 38°C, and pulse rate above 100 a minute.

  • Up to half of people may have asymptomatic chest signs after surgery, and up to one quarter develop symptomatic disease.

  • The main risk factor is the type of surgery, with higher risks associated with surgery to the chest, abdomen, and head and neck compared with other operations.

  • Other risk factors include age over 50 years, COPD, smoking, hypoalbuminaemia, and being functionally dependent.

Prophylactic lung expansion techniques are commonly used to reduce the risk of postoperative pulmonary infection, but we don't know whether they are of benefit in people having abdominal or cardiac surgery.

  • We don't know which is the most effective lung expansion technique to use.

Regional anaesthesia (epidural or spinal), either alone or with general anaesthesia, may reduce the risk of developing postoperative pulmonary infections compared with general anaesthesia alone, although studies have given conflicting results.

  • It has been estimated that one infection would be prevented for every 50 people having regional anaesthesia.

  • Regional anaesthesia is associated with a small risk (around 4/10,000 procedures in total) of seizures, cardiac arrest, respiratory depression, or neurological injury.

Selective postoperative nasogastric decompression reduces the risk of developing postoperative pulmonary infections after abdominal surgery compared with routine use.

  • Routine use does not shorten the return of bowel function, and tube insertion is uncomfortable in up to one fifth of people.

We don't know whether advice to stop smoking before surgery reduces the risk of developing postoperative pulmonary infections.

  • It is possible that people need to have stopped smoking at least 2 months before surgery in order to reduce the risks of chest infection.

About this condition

Definition

A working diagnosis of postoperative pulmonary infection may be based on three or more new findings from: cough, phlegm, shortness of breath, chest pain, temperature above 38°C, and pulse rate above 100 a minute. In this review, we focus on postoperative pneumonia. However, as RCTs usually estimate risk for combined outcomes (atelectasis; bronchospasm; bronchitis; pneumonia; respiratory failure, or exacerbation of underlying chronic disease, or both), it has not always been feasible to separate specific pneumonia rates from combined pulmonary outcomes. We examine a selection of pre-, intra-, and postoperative techniques to reduce the risk of postoperative pulmonary complications. In this review, the diagnosis of pneumonia implies consolidation observed in a chest radiograph.

Incidence/ Prevalence

Reported morbidity for chest complications depends on how carefully they are investigated, and on the type of surgery performed. One observational study found blood gas and chest radiograph abnormalities in about 50% of people after open cholecystectomy. However, less than 20% of these had abnormal clinical signs, and only 10% had a clinically significant chest infection. One observational study found the incidence of pneumonia to be 17.5% after thoracic and abdominal surgeries. Another observational study found the incidence of pneumonia to be 2.8% (using a more restrictive definition of pneumonia) after laparotomy.

Aetiology/ Risk factors

Risk factors include: increasing age (over 50 years), with the odds of developing postoperative pneumonia systematically increasing with each decile above the age of 50 years; functional dependency; COPD; weight loss of over 10% in the last 6 months; impaired sensorium (acute confusion/delirium associated with current illness); cigarette smoking; recent alcohol use; and blood urea nitrogen level greater than 7.5 mmol/L. Serum albumin level of less than 35 g/L is also a risk factor for the development of overall postoperative pulmonary complications. The strongest risk factor, however, is the type of surgery (particularly aortic aneurysm repair, thoracic surgery, abdominal surgery, neurosurgery, head and neck surgery, and vascular surgery). Obesity was not found to be an independent risk factor in a recent systematic review of preoperative pulmonary risk stratification for non-cardiothoracic surgery. Nasogastric tube placement was found to be a risk factor by multivariate analysis in the development of postoperative pulmonary complications in a systematic review of blinded studies examining risk factors for pulmonary complications after non-thoracic surgery.

Prognosis

In one large systematic review (search date 1997, 141 RCTs, 9559 people), 10% of people with postoperative pneumonia died. If systemic sepsis ensues, mortality rate is likely to be high. Pneumonia delays recovery from surgery, and poor tissue oxygenation may contribute to delayed wound healing. In a cohort of 160,805 US veterans having major non-cardiac surgery, 1.5% of people developed postoperative pneumonia, and the 30-day mortality rate was 10-fold higher in these people compared with those without postoperative pneumonia.

Aims of intervention

To prevent the development of postoperative pulmonary infection; to minimise adverse effects of treatment.

Outcomes

Pulmonary infection: rates of clinically diagnosed postoperative pulmonary infection (as in the definition above); adverse effects. Postoperative pulmonary complications are a commonly used outcome, but this combines pulmonary infections with other adverse outcomes. Where possible, we have reported on postoperative pulmonary infections in favour of pulmonary complications. The term "postoperative pulmonary complications" is used to report complications that include combinations of: atelectasis; bronchospasm; bronchitis; pneumonia; respiratory failure, and exacerbation of underlying chronic pulmonary disease, or both, when not possible to report on specific rates of pneumonia.

Methods

Clinical Evidence search May 2007. The following databases were used to identify studies for this review: Medline 1966 to May 2007, Embase 1980 to May 2007, and The Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Clinical Trials 2007, Issue 2. Additional searches were carried out using these websites: NHS Centre for Reviews and Dissemination (CRD) — for Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA), Turning Research into Practice (TRIP), and NICE. Abstracts of the studies retrieved from the initial search were assessed by an information specialist. Selected studies were then sent to the contributor for additional assessment, using predetermined criteria to identify relevant studies. Study design criteria for inclusion in this review were: published systematic reviews and RCTs in any language, at least single-blinded, and containing more than 25 people, of whom more than 60% were followed up. The minimum length of follow-up was 48 hours postoperatively. Studies described as "open", "open label", or not blinded were included. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the review as required. To aid readability of the numerical data in our reviews, we round percentages up to the nearest whole number. Readers should be aware of this when relating percentages to summary statistics such as RRs and ORs. We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table.

GRADE Evaluation of interventions for Postoperative pulmonary infections.

Important outcomes Pulmonary infection
Studies (Participants) Outcome Comparison Type of evidence Quality Consistency Directness Effect size GRADE Comment
What are the effects of interventions to prevent postoperative pulmonary infections?
2 (165) Pulmonary infection Advice to stop smoking preoperatively versus usual care/control 4 –2 0 –1 0 Very low Quality points deducted for sparse data and incomplete reporting of results. Directness point deducted for low number of events (no events in 1 RCT; 7 events in other)
at least 145 (at least 9745) Pulmonary infection Regional anaesthesia (epidural or spinal) versus general anaesthesia 4 –1 0 –2 0 Very low Quality point deducted for inclusion of quasi-randomised RCTs. Directness points deducted for clinical heterogeneity among RCTs, and for unclear generalisability (inclusion of old RCTs that may have overlooked recent advances in anaesthesia)
at least 36 (at least 4421) Pulmonary infection Prophylactic lung expansion techniques versus no intervention or versus each other 4 –1 –1 –1 0 Very low Quality point deducted for incomplete reporting of results. Consistency point deducted for conflicting results. Directness point deducted for use of composite outcomes (pulmonary complications)
22 (3448) Pulmonary infection Selective versus routine postoperative nasogastric decompression after abdominal surgery 4 –1 0 –1 0 Low Quality point deducted for weak methods in 2 RCTs (unclear randomisation and length of follow-up). Directness point deducted for weak outcomes (composite in 1 systematic review; not defined in 2 RCTs)
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We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.

Glossary

Continuous positive airway pressure (CPAP)

This involves applying positive pressure from a blower motor to the upper airway through tubing and a soft nasal mask or a facemask. It provides a "pneumatic splint" to the upper airway. Because nasal delivery is the most common in the published literature, we refer to "nasal CPAP".

Intermittent positive pressure breathing

A type of physiotherapy which involves assisted breathing with a pressure cycled ventilator triggered into inspiration by the user and allowing passive expiration. The user begins to inhale through the machine, which senses the breath and augments it by delivering gas to the user. When a preset pressure is reached, the machine stops delivering gas and allows the user to breathe out. In most devices, the inspiratory sensitivity, flow rate, and pressure can be varied to suit the user's needs, but some devices adjust the sensitivity and flow automatically. The aim is to increase lung volume, which is thought to cause a reduction in airways resistance and an improvement in ventilation.

Low-quality evidence

Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

Neuraxial blockade

Involves spinal or epidural anaesthesia.

Very low-quality evidence

Any estimate of effect is very uncertain.

Disclaimer

The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients.To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.

Contributor Information

Dr Michelle Conde, South Texas Veterans Health care System and Division of General Medicine, Department of Medicine, University of Texas Health Center at San Antonio, San Antonio, USA.

Dr Valerie Lawrence, South Texas Veterans Health care System and Division of General Medicine, Department of Medicine, University of Texas Health Center at San Antonio, San Antonio, USA.

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BMJ Clin Evid. 2008 Sep 29;2008:2201.

Advice to stop smoking preoperatively

Summary

We don't know whether advice to stop smoking before surgery reduces the risk of developing postoperative pulmonary infections.

It is possible that people need to have stopped smoking at least 2 months before surgery in order to reduce the risks of chest infection.

Benefits and harms

Advice to stop smoking preoperatively versus usual care/control:

We found one systematic review (search date 2005), which identified two RCTs that reported the effects of smoking cessation interventions on postoperative complications. The review did not pool data, and so we report data from the individual RCTs. See further information on studies for details of postoperative complication rate.

Pulmonary infection

Advice to stop smoking preoperatively compared with usual care/control We don't know whether smoking cessation interventions given 2 to 8 weeks before surgery are more effective at reducing postoperative pulmonary infections or postoperative pneumonia in people undergoing hip or knee replacement or colorectal surgery (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Postoperative pulmonary infections

RCT		 120 people who smoked daily and were scheduled for hip or knee replacement
In review 		Pulmonary infection
0% with smoking-cessation intervention
0% with usual care
Significance not assessed
Low rate of pulmonary infection is consistent with the inherent low risk for postoperative pulmonary infections associated with elective hip or knee replacement

RCT		 60 people who smoked daily, undergoing colorectal surgery
In review 		Postoperative pneumonia (verified by radiograph)
3/27 (11%) with smoking-cessation programme started 2–3 weeks before surgery
4/30 (13%) with control (normal smoking habits before surgery)
Reported as not significant
P value not reported
The RCT may have been too small to detect a clinically important difference between groups 		Not significant
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Adverse effects

No data from the following reference on this outcome.

Further information on studies

The RCT found that the smoking-cessation intervention significantly reduced overall complication rates compared with usual care (10/56 [18%] with cessation intervention v 27/52 [52%] with usual care; P <0.001). However, the reduced complications were primarily wound complications and UTIs.

Comment

A systematic review of prospective cohort studies (12 studies identified) exploring the effects of preoperative smoking cessation and the risk of postoperative complications in adult smokers found a higher incidence of overall postoperative complications in current smokers than in past smokers. This review was qualitative and did not pool data. Two cohort trials identified by the systematic review reported that people who had recently stopped smoking (abstinence less than 2 months before surgery) had a higher overall postoperative pulmonary complication rate than current smokers. However, another cohort trial identified by the systematic review found no difference in postoperative pulmonary complication rates among all subgroups of smokers, including recent quitters (smoking cessation of less than 2 months’ duration). Although preoperative smoking-cessation advice has not been shown to be any more effective than usual care at reducing postoperative pulmonary complication rates, and the optimal duration of non-smoking before surgery remains unclear, smoking cessation has long-term benefits, and advice should be offered to people motivated to stop smoking. RCTs to determine the optimal smoke-free duration before surgery are feasible and should be undertaken.

Substantive changes

No new evidence

BMJ Clin Evid. 2008 Sep 29;2008:2201.

Regional (epidural or spinal) anaesthesia

Summary

Regional anaesthesia (epidural or spinal), either alone or with general anaesthesia, may reduce the risk of developing postoperative pulmonary infections compared with general anaesthesia alone, although studies have given conflicting results.

It has been estimated that one infection would be prevented for every 50 people having regional anaesthesia.

Regional anaesthesia is associated with a small risk (around 4/10,000 procedures in total) of seizures, cardiac arrest, respiratory depression, or neurological injury.

Benefits and harms

Regional anaesthesia (epidural or spinal) versus general anaesthesia:

We found three systematic reviews and one subsequent RCT. The first systematic review (search date 1997, 141 RCTs) compared intraoperative neuraxial blockade (with or without general anaesthesia) versus no neuraxial blockade (primarily general anaesthesia plus systemic analgesia) in people undergoing mixed surgical procedures. The review compared all types of intraoperative neuraxial blockade versus no neuraxial blockade, and had more power compared with the other reviews identified. The second systematic review (search date not reported; 2162 people) included 15 randomised or quasi-randomised trials of hip fracture repair, 12 of which were identified by the first review. The third systematic review (search date 2005) was qualitative in nature and identified and included the results of the other two systematic reviews (see further details on studies). The review noted potential sources of bias in the first review; see further information on studies for full details.

Pulmonary infection

Regional anaesthesia compared with general anaesthesia Intraoperative neuraxial blockade (alone or in combination with general anaesthesia) may be more effective than no neuraxial blockade (primarily general anaesthesia plus systemic analgesia) at reducing postoperative pneumonia in people undergoing mixed surgical procedures. We don't know whether neuraxial blockade is more effective than general anaesthesia at reducing postoperative pneumonia in people having hip fracture repair, or whether local anaesthesia is more effective than general anaesthesia at reducing pneumonia at 30 days in people having carotid artery surgery (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Pneumonia

Systematic review		 9559 people undergoing mixed surgical procedures
141 RCTs in this analysis		 Pneumonia
149/4871 (3%) with neuraxial blockade
238/4688 (5%) with general anaesthesia
RR 0.61
95% CI 0.48 to 0.76
NNT 50
95% CI 36 to 82 		Small effect size neuraxial blockade

Systematic review		 1096 people undergoing surgery for repair of hip fracture
8 RCTs in this analysis		 Pneumonia
27/529 (5.1%) with neuraxial blockade
31/567 (5.5%) with general anaesthesia
OR 0.92
95% CI 0.53 to 1.59 		Not significant

RCT		 186 people with carotid artery stenosis Pneumonia within 30 days after surgery
1/91 (1%) with local anaesthesia
0/95 (0%) with general anaesthesia
P >0.05
The number of events may have been too few to detect a clinically important difference 		Not significant
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No data from the following reference on this outcome.

Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

RCT		 186 people with carotid artery stenosis Intraoperative complications
with local anaesthesia
with general anaesthesia

RCT		 186 people with carotid artery stenosis Neurological complications
2/91 (2.2%) with local anaesthesia
2/95 (2.1%) with general anaesthesia
Reported as not significant
P value not reported 		Not significant

Systematic review		 People undergoing surgery for repair of hip fracture Complications
with neuraxial blockade
with general anaesthesia
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No data from the following reference on this outcome.

Further information on studies

The review (search date 1997) included RCTs comparing intraoperative neuraxial blockade with or without general anaesthesia. No neuraxial blockade primarily consisted of general anaesthesia plus systemic analgesia. The review found some evidence that the risk of developing pneumonia may be lower after thoracic epidural anaesthesia than after lumbar epidural or spinal anaesthesia, but it did not perform a meta-analysis. Sensitivity analysis One sensitivity analysis carried out by the review suggested that the overall benefits of neuraxial blockade in reducing all types of postoperative complication held for all types of surgery studied. Overall benefit The overall benefit of neuraxial blockade was independent of whether it was combined with general anaesthesia. The review found that neuraxial blockade significantly reduced the incidence of overall mortality compared with no neuraxial blockade (103/4871 [2%] with neuraxial blockade v 144/4688 [3%] with no neuraxial blockade; OR 0.70, 95% CI 0.54 to 0.90, P = 0.006). In addition, neuraxial blockade significantly reduced the number of other serious complications, such as the incidence of venous thromboembolism, compared with no neuraxial blockade (145/4871 [3%] with neuraxial blockade v 220/4688 [5%] with no neuraxial blockade; OR 0.56, 95% CI 0.43 to 0.72).

The qualitative systematic review, which assessed strategies to reduce postoperative pulmonary complications, noted potential sources of bias in the one of the other reviews identified, including the inclusion of clinically heterogeneous studies, trials with samples of fewer than 50 people, and older studies (most of the included studies were published before 1990). These issues may mean that the results in favour of neuraxial blockade may have overlooked advances in anaesthesia technology during the past 15 years.

Comment

General adverse effects

One large prospective French cohort study (30,413 epidural anaesthetics) reported on the incidence of harms from epidural analgesia. This study estimated the frequency of cardiac arrest (usually due to inadvertent intravascular injection of local anaesthetic) as 1/10,000; seizures (usually the same cause) as 1.3/10,000; neurological injury as 2/10,000; radiculopathy as 1.6/10,000; and paraplegia as 0.3/10,000. There were no deaths attributable to epidural analgesia. In a large US case series (1297 people receiving epidurals), 0.4% of people were judged to need naloxone to reverse the adverse effects of epidural opioids on breathing. One case series reported three cases in which epidural analgesia was thought to contribute to the development of postoperative pressure sores. Inadvertent dural puncture with the epidural needle can cause headache (frequency increases with gauge of needle). Effective pain relief can delay recognition of surgical complications, such as anastomotic breakdown, peritonitis, or compartment compression syndrome of the legs.

Clinical guide

Although the review focusing on the effects of neuraxial blockade in hip fracture repair surgery found no significant benefit for this technique compared with general anaesthesia, hip fracture repair surgery is associated with an inherently low risk of pneumonia, which could potentially underestimate the benefit of neuraxial blockade in other types of higher-risk surgery. Overall, there is some evidence of benefit for neuraxial blockade (with or without general anaesthesia) compared with general anaesthesia alone. Other factors that may be considered are locally available resources, and the potential benefit of neuraxial blockade to reduce other complications. Further RCTs evaluating neuraxial blockade versus general anaesthesia alone may be unlikely to be undertaken, given the increasing use of combined intraoperative modalities with postoperative epidural analgesia.

Substantive changes

Regional (epidural or spinal) anaesthesia One RCT in people having carotid surgery added. The RCT found no significant difference between local and general anaesthesia in rate of pneumonia within 30 days after surgery. However, the number of events may have been too small to detect a clinically important difference between the techniques. Categorisation unchanged (Likely to be beneficial).

BMJ Clin Evid. 2008 Sep 29;2008:2201.

Prophylactic lung expansion techniques

Summary

Prophylactic lung expansion techniques are commonly used to reduce the risk of postoperative pulmonary infection, but we don't know whether they are of benefit in people having abdominal or cardiac surgery.

We don't know which is the most effective lung expansion technique.

Benefits and harms

Prophylactic lung expansion techniques versus no intervention or versus each other:

We found three systematic reviews, and one additional RCT. The reviews reached different conclusions on the effectiveness of prophylactic lung expansion techniques in reducing rate of postoperative pulmonary infections (see further information on studies for details of review design and conclusions). One of the reviews (search date 2005, 2 reviews/meta-analyses, 5 RCTs, total number of people in analyses not reported) was qualitative in nature and did not pool data. Two reviews (search date 2005, 35 RCTs, total number of people in RCTs not reported and search date 2003, 18 RCTs, 1457 people) did not pool data, and so we report the findings of the individual RCTs identified by the reviews.

Pulmonary infection

Prophylactic lung expansion techniques compared with no intervention or compared with each other We don't know whether prophylactic lung expansion techniques are more effective than control at reducing postoperative infection, pneumonia, or composite outcomes of postoperative pulmonary complications (which included infection), or whether lung expansion techniques differ in their effectiveness at preventing postoperative infections or postoperative pulmonary complications. However, results were inconsistent and varied by the exact analysis performed, the lung expansion technique used, and the type of surgery undertaken (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Pneumonia

RCT		 102 people undergoing cholecystectomy
In review 		Pneumonia
7/51 (14%) with deep-breathing exercises plus directed cough plus postural drainage therapy
19/51 (37%) with control
RD –23.6%
95% CI –40% to –7% 		Effect size not calculated deep-breathing exercises plus directed cough plus postural drainage therapy

RCT		 81 people (35 men), mean age 64.1 years (range 18–84 years), undergoing elective upper abdominal surgery
In review 		Pneumonia
0/40 (0%) with deep-breathing exercises plus directed cough
1/41 (2%) with no prophylaxis
RD –2.4%
95% CI –9% to +4% 		Not significant

RCT
3-armed trial 		137 people undergoing cholecystectomy
In review 		Pneumonia
4/45 (9%) with deep-breathing exercises plus directed cough plus postural drainage therapy
1/45 (2%) with control
RD +6.7% for lung expansion v control
95% CI –3% to +16% 		Not significant

RCT
3-armed trial 		137 people undergoing cholecystectomy
In review 		Pneumonia
4/47 (9%) with deep-breathing exercises plus directed cough plus postural drainage therapy plus bronchodilator aerosol
1/45 (2%) with control
RD +6.3% for lung expansion v control
95% CI –3% to +15% 		Not significant

RCT		 50 people undergoing upper or lower abdominal surgery
In review 		Pneumonia
1/29 (3%) with deep-breathing exercises plus directed cough
0/21 (0%) with control
RD +3.4%
95% CI –7% to +13% 		Not significant

RCT		 40 people undergoing cholecystectomy
In review 		Pneumonia
0/20 (0%) with incentive spirometry
1/20 (5%) with control
RD –5.0%
95% CI –18% to +8% 		Not significant

RCT		 204 people (166 men), mean age 63 years (SD 11.8), undergoing elective intra-abdominal vascular surgery
In review 		Pneumonia (per CDC criteria)
2/99 (2%) with nasal continuous positive-airway pressure for 12 hours after surgery
5/105 (5%) with control (O2 by nasal cannula to keep saturation above 95%)
RD –2.8%
95% CI –8% to +2% 		Not significant

RCT		 368 people (158 men), mean age 53.3 years (range 19–92 years), undergoing elective open abdominal surgery
In review 		Pneumonia
0.6% with deep-breathing exercises with or without positive respiratory pressure throughout expiration
7% with no prophylaxis
Absolute numbers not reported
P <0.05 		Effect size not calculated deep-breathing exercises with or without positive respiratory pressure throughout expiration
Postoperative pulmonary complications (unspecified)

RCT		 81 people (35 men), mean age 64.1 years (range 18–84 years), undergoing elective upper abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
3/40 (8%) with deep-breathing exercises plus directed cough
8/41 (20%) with control
RD –12%
95% CI –27% to +3% 		Not significant

RCT
4-armed trial 		172 people undergoing upper or lower abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
9/42 (21%) with incentive spirometry
21/44 (48%) with control
RD –26.3% for incentive spirometry v control
95% CI –46% to –7% 		Effect size not calculated incentive spirometry

RCT
4-armed trial 		172 people undergoing upper or lower abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
9/41 (22%) with deep-breathing exercises plus directed cough
21/44 (48%) with control
RD –25.8% for deep breathing exercise plus directed cough v control
95% CI –45% to –6% 		Effect size not calculated deep-breathing exercises plus directed cough

RCT
4-armed trial 		172 people undergoing upper or lower abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
10/45 (22%) with intermittent positive-pressure breathing (IPPB)
21/44 (48%) with control
RD –25.5% for intermittent positive-pressure breathing v control
95% CI –45% to –6% 		Effect size not calculated intermittent positive-pressure breathing

RCT		 50 people undergoing upper or lower abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
5/29 (17%) with deep-breathing exercises plus directed cough
3/21 (14%) with control
RD +3.1%
95% CI –17% to +23% 		Not significant

RCT		 40 people undergoing upper abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
8/20 (40%) with incentive spirometry
6/20 (30%) with control
RD +10.0%
95% CI –19% to +39% 		Not significant

RCT
3-armed trial 		200 people undergoing upper abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
29/50 (58%) with intermittent positive-pressure breathing (IPPB)
48/100 (48%) with control
RD +10.0% for intermittent positive-pressure breathing v control
95% CI –7% to +27% 		Not significant

RCT
3-armed trial 		200 people undergoing upper abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
28/50 (56%) with intermittent positive-pressure breathing (IPPB) with more intensive therapy
48/100 (48%) with control
RD +8.0% for IPPB with more intensive therapy v control
95% CI –9% to +25% 		Not significant

RCT		 64 people undergoing upper or lower abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
1/32 (3%) with continuous positive-airway pressure
0/32 (0%) with control
RD +3.1%
95% CI –5% to +11% 		Not significant

RCT		 230 people having open heart surgery Postoperative pulmonary complications (unspecified)
5/115 (4%) with physiotherapy plus deep-breathing exercises
3/115 (3%) with physiotherapy without deep-breathing exercises
P = 0.72 		Not significant

RCT		 876 people (430 men) median age 55 years (IQR 32–72), undergoing abdominal surgery
In review 		Postoperative pulmonary complications (unspecified)
16% with incentive spirometry
15% with control (chest physiotherapy only)
Significance not assessed

RCT		 155 low-risk people, median age 36 years (IQR 29–44), undergoing abdominal surgery
In review
Subgroup analysis		 Postoperative pulmonary complications (unspecified)
6/79 (8%) with incentive spirometry
8/76 (11%) with deep-breathing exercises
P = 0.50 		Not significant

RCT		 301 high-risk people, median age 68 years (IQR 58–76), undergoing abdominal surgery
In review
Subgroup analysis		 Postoperative pulmonary complications (unspecified)
29/152 (19%) with incentive spirometry
20/149 (13%) with incentive spirometry plus conventional chest physiotherapy
P = 0.18 		Not significant

RCT		 82 people undergoing inguinal hernia surgery
In review 		Postoperative pulmonary complications (unspecified)
8/40 (20%) with deep-breathing exercises
5/42 (12%) with control
RD +8.1%
95% CI –8% to +24% 		Not significant

RCT		 54 women undergoing hysterectomy
In review 		Postoperative pulmonary complications (unspecified)
1/27 (4%) with deep-breathing exercises plus directed cough
0/27 (0%) with control
RD +3.7%
95% CI –6% to +13% 		Not significant
Atelectasis or infiltrate on chest radiograph

Systematic review		 People undergoing any upper abdominal surgery; number of people in analysis not reported
In review
14 RCTs in this analysis		 Atelectasis or infiltrate on chest radiograph
with incentive spirometry
with no treatment
Absolute results not reported
OR 0.44
95% CI 0.18 to 0.99 		Moderate effect size prophylactic lung expansion

Systematic review		 People undergoing any upper abdominal surgery; number of people in analysis not reported
In review
4 RCTs in this analysis		 Atelectasis or infiltrate on chest radiograph
with incentive spirometry
with deep-breathing exercise
Absolute results not reported
OR 0.91
95% CI 0.57 to 1.4 		Not significant

Systematic review		 People undergoing any upper abdominal surgery; number of people in analysis not reported
In review
3 RCTs in this analysis		 Atelectasis or infiltrate on chest radiograph
with incentive spirometry
with intermittent positive-pressure breathing
Absolute results not reported
OR 0.73
95% CI 0.39 to 1.36 		Not significant

Systematic review		 People undergoing any upper abdominal surgery; number of people in analysis not reported
In review
2 RCTs in this analysis		 Atelectasis or infiltrate on chest radiograph
with intermittent positive-pressure breathing (IPPB)
with deep-breathing exercise
Absolute results not reported
OR 0.94
95% CI 0.28 to 3.17 		Not significant
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Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Adverse effects

Systematic review		 Number of people not reported Discomfort
with lung expansion techniques
with control

Systematic review		 Number of people not reported
4 RCTs in this analysis		 Adverse effects
with lung expansion technique
with control
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No data from the following reference on this outcome.

Further information on studies

The review compared strategies to reduce postoperative pulmonary complications after non-cardiothoracic surgeries (any upper abdominal surgery). Conclusion It concluded that lung expansion techniques were beneficial in reducing postoperative pulmonary complications after abdominal surgery. Eligible studies in this review were RCTs with at least 25 people in each arm, systematic reviews, or meta-analysis.

The review included RCTs deemed to have adequate randomisation that evaluated different forms of lung expansion techniques to prevent pulmonary complications after abdominal surgery. Eleven (1147 people) of the 35 RCTs compared a lung expansion technique versus a control (no intervention) group, and reported on postoperative infection rate or postoperative pulmonary complications. Conclusion The review reported that only a few studies found prophylactic respiratory physiotherapy (including incentive spirometry, continuous positive airway pressure, and breathing exercises) after abdominal surgery to be beneficial, and concluded that its routine use did not seem justified. The review identified 22 RCTs (2,734 people) comparing different lung expansion techniques (IS, CPAP, physiotherapy, IPPB, positive expiratory mask ± inspiratory resistance) versus each other. The review found no technique to be significantly superior to the others assessed.

The review included people having cardiac surgery. Four RCTs had a no-intervention control group. Conclusion The review found no difference between any lung expansion technique and no intervention for any postoperative infection outcome (meta-analysis not performed, no further statistical data available). The review found insufficient evidence for benefit of prophylactic respiratory physiotherapy after cardiac surgery. Three of the RCTs did not meet Clinical Evidence inclusion criteria and are not reported.

One review, identified by another review discussed here, did not pool data because of clinical heterogeneity among RCTs. The review identified 4 RCTs (number of people not reported) of any type of upper or lower abdominal surgery. The review reported that, in 3 studies, all with fewer than 25 people/group), incentive spirometry was no better than deep breathing exercises or no treatment and was inferior to continuous positive-airway pressure or positive respiratory pressure throughout expiration. In a fourth study (41–44 people/group), incentive spirometry, deep breathing exercises, and intermittent positive-pressure breathing (postoperative pulmonary complication rates of 21%, 22%, and 22%, respectively) were equally superior to no prophylaxis (postoperative pulmonary complication rate 48%; P <0.05 for all comparisons). No further information given on the separate RCTs identified.

Comment

Clinical guide

There is some evidence that lung expansion techniques are of benefit in reducing overall postoperative pulmonary complications compared with no intervention in patients having abdominal procedures. We found no evidence that lung expansion techniques specifically reduce postoperative pneumonia. There is insufficient evidence of benefit of these techniques after cardiac surgery. Although lung expansion techniques are almost universally used perioperatively, especially in high-risk patients having high-risk procedures, there is insufficient evidence from trials that they are beneficial compared with early mobilisation, or that any one lung expansion modality is superior. RCTs would be feasible and should be undertaken.

Substantive changes

Lung expansion techniques One systematic review added. The review found no significant difference between any lung expansion technique versus no intervention for postoperative pneumonia after abdominal surgery and any postoperative infection outcome after cardiac surgery. Evidence now reported does not support a categorisation of Beneficial. Categorisation changed from Beneficial to Unknown effectiveness.

BMJ Clin Evid. 2008 Sep 29;2008:2201.

Nasogastric decompression after abdominal surgery

Summary

Selective postoperative nasogastric decompression reduces the risk of developing postoperative pulmonary infections after abdominal surgery compared with routine use.

Routine use does not shorten the return of bowel function, and tube insertion is uncomfortable in up to one fifth of people.

Benefits and harms

Selective versus routine postoperative nasogastric decompression after abdominal surgery:

We found one systematic review (search date 2004, 28 RCTs, 4194 people) reported in two publications. The review compared selective use of nasogastric decompression versus routine prophylactic use of nasogastric decompression after elective or emergency abdominal surgery (laparoscopic surgery was not included). We found three subsequent RCTs.

Pulmonary infection

Selective use of nasogastric decompression after abdominal surgery compared with routine nasogastric decompression Selective use of nasogastric decompression after abdominal surgery may be more effective than routine nasogastric decompression at reducing postoperative pneumonia, postoperative pulmonary infections (not further defined), and respiratory complications (not further defined) in people undergoing surgery for hepatic resection, colorectal carcinoma, or surgery of the infrarenal aorta. However, we don't know whether it is more effective at reducing the composite outcome of pulmonary complications (pneumonia, atelectasis, or both) in people having elective and emergency abdominal surgery (low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Pneumonia

RCT		 200 people having hepatic resection Pneumonia
5/100 (5%) with removal of the nasogastric tube at the end of the operation (selective use)
13/100 (13%) with routine nasogastric decompression
P = 0.047 		Effect size not calculated selective use
Postoperative pulmonary complications (unspecified)

Systematic review		 2892 people who had undergone abdominal surgery
19 RCTs in this analysis		 Pulmonary complications (pneumonia or atelectasis, or both)
148/1448 (10%) with routine nasogastric tube gastric decompression
104/1444 (7%) with selective postoperative nasogastric decompression
RR (for fewer complications) 1.35
95% CI 0.98 to 1.86
P = 0.07 		Not significant

RCT		 316 people having surgery for colorectal carcinoma Postoperative pulmonary infection (not further defined)
1/161 (1%) with removal of the nasogastric tube 12–24 hours after surgery (selective use)
7/155 (5%) with routine nasogastric decompression
P = 0.034
The method of randomisation and length of follow-up of the RCT were unclear 		Effect size not calculated selective use

RCT		 40 people having surgery of the infrarenal aorta Postoperative respiratory complications (not further defined)
0/20 (0%) with removal of the nasogastric tube at the time of tracheal extubation (selective use)
5/20 (25%) with routine use
P = 0.023
The method of randomisation and length of follow-up of the RCT were unclear 		Effect size not calculated selective use
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Adverse effects

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Wound infection

Systematic review		 3577 people who had undergone abdominal surgery
15 RCTs in this analysis		 Wound infections
77/1287 (6%) with selective use
58/1283 (5%) with routine use
RR for routine use v selective use 0.76
95% CI 0.56 to 1.04
P = 0.08 		Not significant
Nausea and vomiting

RCT		 200 people having hepatic resection Nausea
31/100 (31%) with removal of the nasogastric tube at the end of the operation (selective use)
20/100 (20%) with routine use
Reported as not significant
P value not reported 		Not significant

RCT		 40 people having surgery of the infrarenal aorta Nausea
3/20 (15%) with removal of the nasogastric tube at the time of tracheal extubation (selective use)
3/20 (15%) with routine use
Reported as not significant
P value not reported 		Not significant

RCT		 200 people having hepatic resection Emesis on removal of nasogastric tube
10/100 (10%) with removal of the nasogastric tube at the end of the operation (selective use)
2/100 (2%) with routine use
P = 0.011 		Effect size not calculated routine use

RCT		 40 people having surgery of the infrarenal aorta Vomiting
2/20 (10%) with removal of the nasogastric tube at the time of tracheal extubation (selective use)
3/20 (15%) with routine use
Reported as not significant
P value not reported 		Not significant
Tube replacement

RCT		 40 people having surgery of the infrarenal aorta Tube replacement
1/20 (5%) with removal of the nasogastric tube at the time of tracheal extubation (selective use)
2/20 (10%) with routine use
Reported as not significant
P value not reported 		Not significant
Complications (other)

RCT		 316 people having surgery for colorectal carcinoma Abdominal distension
3/161 (3%) with removal of the nasogastric tube 12–24 hours after surgery (selective use)
1/155 (1%) with routine use
P = 0.623 		Not significant

Systematic review		 480 people who had undergone abdominal surgery
Data from 1 RCT		 Ventral hernias
15/229 (7%) with selective use
8/251 (3%) with routine use
RR for routine use v non-routine use 0.47
95% CI 0.20 to 1.13
P = 0.09 		Not significant

RCT		 200 people having hepatic resection Severe discomfort
with removal of the nasogastric tube at the end of the operation (selective use)
with routine use
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Further information on studies

Heterogeneity among trials precluded reporting a summary statistic for discomfort associated with nasogastric tube placement. The review reported that nasogastric tube re-insertion occurred with insufficient frequency. Oesophageal perforation related to nasogastric tube insertion was not reported in any of the included studies.

Comment

Clinical guide:

There is some evidence that routine nasogastric decompression after abdominal surgery is harmful compared with selective nasogastric decompression, and may increase the risk of developing postoperative pulmonary infections. Additionally, routine nasogastric decompression does not seem to speed up bowel-function return, and insertion is associated with severe discomfort.

Substantive changes

Nasogastric decompression after abdominal surgery (selective versus routine) One systematic review and three subsequent RCTs added. The review found no significant difference between selective nasogastric decompression and routine nasogastric decompression in postoperative pulmonary complication rates, but rates of infection were lower with selective nasogastric decompression. Selective nasogastric decompression was associated with a non-significant trend toward increased risk of wound infection. The three subsequent RCTs all found a significant decrease in respiratory complications with selective compared with routine nasogastric decompression. However, the RCTs assessed people undergoing different types of surgery. Categorisation set at Likely to be beneficial.

Articles from BMJ Clinical Evidence are provided here courtesy of BMJ Publishing Group

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