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Correspondence |

Commentary on the Study of the Efficacy of Lung Expansion Techniques on Alterations in Postoperative Pulmonary Complications FREE TO VIEW

Piers Gattenby, MD; Javed Sultan, MD; Sarah Gregory, PGDip (Physiotherapy); Ben Creagh-Brown, PhD
Author and Funding Information

FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

CORRESPONDENCE TO: Ben Creagh-Brown, PhD, Royal Surrey County Hospital – Intensive Care and Respiratory Medicine, Egerton Rd, Guildford, Surrey, England


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(2):606-607. doi:10.1016/j.chest.2015.10.079
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Published online

We congratulate Lunardi et al on their study in CHEST (October 2015) describing the efficacy of lung expansion techniques (LETs) on alterations in postoperative pulmonary complications (PPC) following upper abdominal surgery. However, we believe that the study’s significant flaws preclude drawing conclusions that might influence clinical practice.

Meaningful comparison between the four groups of interventions has several prerequisites. First, the size of each cohort must be sufficient for the comparison to have adequate statistical power. Although the authors mention a sample size calculation, they do not provide the estimated effect size. Second, the groups should be matched for all but the intervention, which is not the case. In particular, the proportion of patients having an esophagectomy (associated with the highest rates of PPC) was unmatched between the groups: control, 0 of 35; flow incentive spirometry, 2 of 33; deep breathing, 6 of 35; and volume incentive spirometry, 1 of 34. This imbalance alone could account for the observed increased rate of PPC in the deep breathing group. The population studied was extremely heterogeneous, both with regard to type of operation and route of access, with laparoscopies and laparotomies considered together. The patients were at intermediate risk of PPC (based on a 10% incidence of PPC); to maximally demonstrate a reduction in PPC, it would have been prudent to selectively study those at the highest risk.

Using an end point of the incidence of unspecified PPC is imperfect because the different PPC are not of equal clinical significance: atelectasis is less significant than pneumonia or respiratory failure. The choice of physiological variables was unusual, and it would be interesting for the authors to comment on their choice of measures and why alternatives (eg, cough peak flow, maximum expiratory pressure, sniff nasal inspiratory pressure) were not studied. Finally, external validity may be limited because the described routine management is divergent from what we consider standard practice; namely, the absence of use of epidural anesthesia.

The conclusions are overstated. First, although LETs may not have altered thoracoabdominal mechanics as measured by these devices, this finding does not mean that alternative measures might not be altered (perhaps measures that relate more closely to PPC). Most importantly, the assertion that the LETs do not prevent PPC is not supported by the data. This claim is possibly a type II error due to inadequate sample size. The effect of LETs on PPC is important and warrants an adequately powered study with a sufficiently homogeneous population who are at high risk of PPC.

References

Lunardi A.C. .Paisani D.M. .Marques da Silva C.C. .Cano D.P. .Tanaka C. .Carvalho C.R. . Comparison of lung expansion techniques on thoracoabdominal mechanics and incidence of pulmonary complications after upper abdominal surgery: a randomized and controlled trial. Chest. 2015;148:1003-1010 [PubMed]journal. [CrossRef] [PubMed]
 
Canet J. .Gallart L. .Gomar C. . the ARISCAT Groupet al Prediction of postoperative pulmonary complications in a population-based surgical cohort. Anesthesiology. 2010;113:1338-1350 [PubMed]journal. [CrossRef] [PubMed]
 

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References

Lunardi A.C. .Paisani D.M. .Marques da Silva C.C. .Cano D.P. .Tanaka C. .Carvalho C.R. . Comparison of lung expansion techniques on thoracoabdominal mechanics and incidence of pulmonary complications after upper abdominal surgery: a randomized and controlled trial. Chest. 2015;148:1003-1010 [PubMed]journal. [CrossRef] [PubMed]
 
Canet J. .Gallart L. .Gomar C. . the ARISCAT Groupet al Prediction of postoperative pulmonary complications in a population-based surgical cohort. Anesthesiology. 2010;113:1338-1350 [PubMed]journal. [CrossRef] [PubMed]
 
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