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Three Part Question

Does [pleurotomy] during [IMA harvest] increase the incidence of [post-operative pulmonary complications]?

Clinical Scenario

You are a first year cardiothoracic registrar who is starting to work for a consultant surgeon who always prefers the pleura to remain intact whilst harvesting the internal mammary artery (IMA). The surgeon avoids pleurotomy to reduce pulmonary complications after cardiac surgery, but you wonder whether there is any evidence in the literature to support this practice

Search Strategy

Medline 1966-Oct 2004 using the OVID interface.
[cardiac surgery.mp OR CABG.mp OR coronary art$ bypass graft$.mp OR cardiopulmonary bypass.mp OR exp cardiovascular surgical procedures/ OR heart surgery.mp OR LIMA.mp] AND [exp Pleura/ OR Pleura$.mp OR extrapleur$.mp OR pleurotomy.mp]

Search Outcome

One hundred and fifty-four papers were found of which 19 were relevant. Eleven papers were discounted as they did not compare IMA harvest with intact pleura versus IMA harvest with open pleura, and thus did not directly address the question. There were no meta-analyses on this topic. Three RCTs were identified and the remainder were all cohort studies with small sample/population sizes. These are presented in the table

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ali et al, 1998 Canada	280 patients for elective coronary revascularization using IMA Group I (n=30) pleura intact Group II (n=50) pleurotomy	Single centre PRCT (level 1b)	Pleural effusion on days 0 and 3	Group I 7/130. Group II 30/150 P<0.001	No effusions required tapping 5 group II patients required opening for tamponade Preop FEV1 <80% excluded Significant pneumonia or atelectasis defined as need for antibiotic therapy or ventilatory support
			Postoperative bleeding	4% in both groups
			Significant pneumonia or atelectasis	None in both groups
			Hospital stay	Group I 6-10 days. Group II 6-10 days. No significant difference
Wimmer-Greinecker et al, 1999 Germany	112 patients for coronary revascularization Group A (n=57) pleurotomy Group B (n=55) pleura intact	Single centre PRCT (level 1b)	Blood loss	Group A 608±58 ml. Group B 470±48 ml P=0.027
			Lung function	Greater reduction in FEV1 (Group A 76.0%±1.6 vs Group B 83.2%±1.6; p=0.002). FEV1/FVC (Group A 0.771±0.021 vs Group B 0.832±0.02; P=0.003)
			Pleural effusion and atelectasis	Effusion A=52.6%, B=23.6% (P=0.002). Atelectasis A=42.1%, B=20% (P=0.015)
Noera et al, 1991 Italy	433 CABG with IMA Group 1: Open pleura Group 2: Extrapleural takedown with pleura intact	Single centre PRCT (level 1b)	Transfusion requirements	Significantly lower transfusion rate in group 2
			Postop effusions, elevated hemidiaphragm	Lower but not significant rates of effusion and elevated hemidiaphragm in group 2 vs 1
Bonacchi et al, 2001 Italy	299 elective patients undergoing coronary revascularization Group I (n=80) skeletonized IMA, intact pleura Group II (n=179) pedicled IMA, open pleura Group III (n=30), skeletonized IMA, open pleura	Cohort study (level 2b)	Mechanical ventilation time	Significantly longer in groups II (6.2±2.9 h) and III (6.0±1.1 h) vs I (5.4± 1.2 h); P<0.018, P<0.02 respectively	EF <30% excluded 12 in group I with repair of pleura Decision to skeletonize IMA based on surgeon's experience If there were small breaches of the pleura these were repaired and included in group I Analysis only for surviving patients; 2 died in group I, 7 in II, 1 in III
			Pmax >20 cm H2O	Significant difference in group II (3.2±1 h) vs I (2.3±0.6 h) P=0.001
			Prolonged ventilation (>24 h)	Significant difference in group II (16/179) vs I (1/80) P=0.03
			Pleural effusion	Significant difference in group II (31/186) vs I (5/82) P=0.011
			Thoracocentesis	Significant differences in groups II (31/179) and III (7/30) vs I (5/80) (P=0.027, P<0.027, respectively)
			Atelectasis during ICU	Significant difference in group II (37/179) vs I (6/80) P<0.013
			Intensive care stay	Group I 1.03±0.5 d. Group II 1.4±0.7 d. Group III 1.35±0.4 d. I vs II P=0.005. I vs III P=0.002
Landymore et al, 1990 Canada	106 patients Group 1: 39 valve/SVG Group 2: 34 IMA + pleurotomy Group 3: 33 IMA pleurae intact	Cohort study (level 3b)	Diaphragmatic elevation a) prior to discharge	1-21%; 2-77%; 3-24%	No statistical analysis
			Diaphragmatic elevation b) at three months	1-5%; 2-47%; 3-6%
			Pleural effusions a) prior to discharge	1-26%; 2-91%; 3-58%
			Pleural effusions b) at three months	1-3%; 2-15%; 3-0%
Tomita et al, 1994 Japan	99 elective CABG Group 1: 45 BIMA + pleurotomy Group 2: 45 IMA + pleurotomy Group 3: 9 IMA/SVG no pleurotomy	Cohort study (level 3b)	PFTs and CXR post op	No CXR differences between 3 groups. All patients had significant reductions in PFTs but no differences between groups
Rolla et al, 1994 Italy	57 IMA patients Group 1: 32 with pleurotomy Group 2: 25 pleurae intact	Cohort study (level 3b)	Atelectasis on POD 2&6 CXRs	1–22% & 29%; 2–19% & 19% Not significant	Small study. No clinical data. Data described as a percentage of preop value. There was no significant difference in preop values between the two groups.
			Pleural Effusion on POD 2&6 CXRs	1–74% & 48%; 2–52% & 38%; Not significant
			Raised hemidiaphragm on POD 6 CXRs	1–18.5%; 2–14%; Not significant
			PFTs 2 months postop	VC: 1–86.8±1.97; 2–93.6±1.65; P=0.05. FEV1: 1–84.6±1.82; 2–90.9±1.41 P=0.02
Lim et al, 2002 UK	206 elective patients Group I Routine or incidental pleurotomy (n=164) Group II Pleura intact (n=38)	Cohort study (level 3b)	Left lung atelectasis	Significantly higher in pleurotomy group (67.7%) vs intact pleura (45.2%) P=0.007.	Heterogeneous group No randomization Small intact pleura group
			Effusion	Pleura intact 46%. Pleura open 43%. P=0.66
			Hospital stay	9 days both groups

Comment(s)

The majority of relevant studies assessed the effect of pleurotomy on post-operative lung function, ventilatory requirements and radiographic changes. Only three studies considered the effect of pleurotomy on clinical outcome [Norea, Lim and Ali et al]. In addition, the lengths of post-operative follow-up varied extensively from 30 min to 3 months. We identified three PRCTs that compared IMA plus pleurotomy to IMA without pleurotomy. The largest PRCT was conducted by Noera et al, the only significant outcome being greater transfusion requirements in the pleurotomy group, although they did find that the rate of pleural effusion and raised left hemidiaphragm was greater albeit not significant in the same group. This study is further supported by Ali et al and Wimmer-Greinecker et al. In the study undertaken by Ali et al., they found that the pleurotomy group had significantly more pleural effusions but that this did not result in more thoracocenteses. Pleurotomy also safe-guarded against the development of cardiac tamponade, with 5 in the closed group but none in the open pleura group. Another clinically relevant outcome was that hospital stay was not different between the two groups. Lim et al assessed post operative chest radiology and length of stay in a heterogeneous group that comprised 138 CABG, 39 valve replacements and 29 CABG + valve replacement. Patients were divided into those with pleurotomy(n=164) and those without (n=42). The pleurotomy group had significantly more atelectasis (67.7% vs. 45.2%, P<0.007) but there was no difference in rates of consolidation, effusion or length of stay. In a relatively small study, Rolla et al recruited 57 patients all of whom had an IMA conduit, therefore blinding chest radiograph reporting. The two groups were of similar size, 32 with pleurotomy, 25 without. There was no difference in post-op chest radiograph on day 2 or 6 and all patients were found to have significantly worse PFTs persisting at 2 months post operation. Tomita et al divided 99 elective CABG cases into 45 BIMA + pleurotomy, 45 IMA + pleurotomy and 9 IMA/SVG only with no pleurotomy and studied PFTs and post-operative chest radiograph changes. There were no differences between groups with all patients suffering significant reductions in PFTs.

Clinical Bottom Line

All patients undergoing cardiac surgery suffer a significant deterioration in Pulmonary Function tests and chest radiograph appearance post-operatively. Pleurotomy seems to compound this with increased rates of atelectasis and pleural effusions, although no impact on clinical outcome or length of hospital stay has been demonstrated.

References

1. Ali IM, Lau P, Kinley CE, Sanalla A. Opening the pleura during internal mammary artery harvesting: advantages and disadvantages. Can J Surg 1996;39:42–45.
2. Wimmer-Greinecker G, Yosseef-Hakimi M, Rinne T, Buhl R, Matheis G, Martens S, Westphal K, Moritz A. Effect of internal thoracic artery preparation on blood loss, lung function and pain. Ann Thorac Surg 1999;67:1078–1082.
3. Noera G, Pensa PM, Guelfi P, Biagi B, Lodi R, Carbone C. Extrapleural takedown of the internal mammary artery as a pedicle. Ann Thorac Surg 1991;52:1292–1294.
4. Bonnacchi M, Prifti E, Giunti G, Salica A, Frati G, Sani G. Respiratory dysfunction after coronary artery bypass grafting and employing bilateral internal mammary arteries: the influence of the intact pleura. Eur J Cardiothorac Surg 2001;19:827–833.
5. Landymore RW and Howell F. Pulmonary complications following myocardial revascularization with the internal mammary graft. Eur J Cardiothorac Surg 1990;4:156–161.
6. Tomita S, Sakata R, Umebayasi Y, Miyata A, Terai H, Ueyama K, Uezu T. Study of pulmonary function after CABG with pleurotomy. Jpn J Thoracic Surg 1994;47:528–532.
7. Rolla G, Fogliati P, Bucca C, Brussino L, Di Rosa E, Di Summa M, Comoglio C, Malara D, Ottino GM. Effect of pleurotomy on pulmonary function after coronary artery bypass grafting with internal mammary artery. Respir Med 1994;88:417–420.
8. Lim E, Callaghan C, Motalleb-Zadeh R, Wallard M, Misra N, Ali A, Halstead JC, Tsui S. A prospective study on clinical outcome following pleurotomy during cardiac surgery. Thorac Cardiovasc Surg 2002;50:287–291.