Prophylactic flap coverage and the incidence of bronchopleural fistulae after pneumonectomy.

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'In pneumonectomy patients, is buttressing the bronchial stump associated with a reduced incidence of bronchopleural fistula?'. Fifty-seven papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. One prospective randomized controlled trial was identified, which found significantly lower rates of bronchopleural fistula and empyema after pneumonectomy with the use of pedicled intercostal flap buttressing. Intercostal muscle flaps and pericardial flaps have been used in case series of high-risk patients, e.g. those with neoadjuvant therapy or extended resections, with low rates of subsequent bronchopleural fistulae. There is the least-reported evidence for thoracodorsal artery perforator and omental flaps. There is relatively little published evidence beyond the single randomized trial identified, with only a few comparison studies to guide clinicians. We conclude that there is evidence for flap buttressing in reducing the risk of bronchopleural fistulae after pneumonectomy in diabetic patients. Flap coverage in other high-risk situations, such as extrapleural or completion pneumonectomy, has been reported in case series with good results. Of the reported techniques, the evidence is strongest for the pedicled inter-costal flap.


INTRODUCTION
A best evidence topic was constructed according to a structured protocol. This is fully described in the ICVTS [1].

CLINICAL SCENARIO
Your next patient is an elderly gentleman requiring a pneumonectomy for lung cancer. He has multiple comorbidities. You are worried about his risk of bronchopleural fistula (BPF) after surgery. Before the operation you consult the literature on types of flap coverage of the bronchial stump and the evidence that they reduce BPF risk.

SEARCH OUTCOME
Fifty-seven papers were found using the reported search. From these, 12 papers were identified as providing the best evidence to answer the question (Table 1).

RESULTS
Sfyridis et al. [2] performed a randomized controlled trial on 70 diabetic patients undergoing pneumonectomy. They randomized patients 1:1 to either intercostal muscle flap reinforcement or no flap coverage. There was a significant reduction in BPF risk (absolute risk reduction 8.8%, relative risk reduction 100%, P = 0.02) and empyema (absolute reduction 7.4%, relative 100%, P = 0.05) in those undergoing flap coverage.
Several large series have also been reported. Algar et al. [3] reported 242 pneumonectomies for malignancy at a single centre. The majority underwent stump coverage. Although several techniques were used, intercostal flaps (44.9%) and pericardial fat pads (PCFPs) (36.1%) predominated. A multivariable analysis of risk factors for BPF was undertaken. Failure to cover the stump was an independent risk factor for BPF, with a relative risk of 1.65, P = 0.039. Other risk factors included long bronchial stumps and right-sided  resections. There were no statistically significant differences between the types of coverage used, but the authors preferred the use of intercostal muscle. Deschamps et al. [4] analysed 713 pneumonectomy patients. In contrast to Algar, univariate analysis showed that the bronchial stump reinforcement was associated with an increased incidence of BPF (7.5% with flap vs 3.6% without flap, P = 0.037). Multiple techniques were used including muscle, parietal pleura and pericardium, serratus anterior, latissimus dorsi and a combination of muscle flaps. However, only 15.6% of patients underwent stump The independent effect of stump coverage was significant, in this large single centre experience Several techniques were used, of which intercostal muscle and mediastinal fat pads were most common The great majority did not undergo neoadjuvant therapy coverage, and the relationship was not confirmed on multivariable modelling. It is possible that the observed crude association was due to confounding by comorbidity. Kleptko et al. [5] reported a cohort study of 129 patients. Multiple coverage techniques were used, with the pericardial flap preferentially chosen by the surgeon in high-risk patients. Coverage of the bronchial stump decreased the incidence of BPF. In the high-risk group, where pericardial flaps were used exclusively, there were no BPFs.
Taghavi et al. [6] studied 93 patients undergoing pericardial flaps. These were drawn from the same institution as Klepetko et al. during a mostly overlapping period. No BPFs were seen.
Lindner et al. [7] analysed 243 patients who underwent flap coverage using either a PCFP or pleura and other local tissues. They did not find a statistically significant difference in the incidence of BPF between using PCFP or pleural flap stump coverage. BPF were seen in both groups (4.9 and 6.0%, respectively). However, the authors favoured the PCFP due to its ease of use and minimal complications.
Hamad et al. [8] report a series of 50 patients undergoing bronchial stump coverage with pericardium following extrapleural pneumonectomy for malignant mesothelioma. There were 2 deaths (4% perioperative mortality) due to cardiac complications, but no BPFs.
Other flap techniques have been reported in smaller series.
Lardinois et al. [9] present a non-randomized consecutive comparison study of 26 patients (1 undergoing either intercostal muscle or diaphragm flaps DF). Groups were matched by age, gender, side of pneumonectomy and tumour stage. 30-day mortality was zero. Complications of atelectasis, pneumonia, visceral herniation and BPF were seen in 8% after intercostal muscle flaps (IF) vs 38% in the DF group (P value not stated). No symptoms of gastro-oesophageal reflux (GORD) were reported in either group. The authors concluded that both methods were effective.
Abolhoda et al. [12] presented a small case-series of high-risk patients undergoing a lobectomy or pneumonectomy (1 patient), using a pedicled Latissimus muscle flap coverage of the bronchial stump. No BPFs were seen. D'Andrilli et al. [13] showed a small case-series using omental flap for coverage of the bronchial stump. There were no early BPFs, but no long-term follow-up.
In summary, the only randomized controlled trial by Sfyridis et al. [2] shows a reduced incidence of BPF and empyema following intercostal flap reinforcement.
There is the evidence from a separate large multivariable analysis that failure to place a flap is an independent predictor of subsequent BPF.
The optimal flap is unclear. Pedicled intercostal muscle is the only flap tested in a randomized trial, but pericardium, PCFP and pleura have also been reported in large series. Smaller series have shown the feasibility of other flaps.

CLINICAL BOTTOM LINE
There is the randomized trial evidence (level 1b) that IF reduce the BPF risk in diabetics. Other level 2 evidence supports flap coverage as a protective measure against BPF.
Coverage of the bronchial stump, probably by intercostal muscle pedicled flap, should be considered in patients considered to be at high risk of BPF.
Conflict of interest: none declared.