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1550 CORRESPONDENCE Ann Thorac Surg2011;92:1548–54

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2. Steyerberg EW. Clinical prediction models. A practical ap-proach to development, validation and updating. New York:Springer, 2009.

ReplyTo the Editor:

We would like to thank Dr Bernard and colleagues [1] for theirinterest in testing the predictive model, which we had previ-ously written on and published regarding prolonged air leak(PAL) [2]. We absolutely agree with the authors’ final statementon the convenience of constructing predictive models based onlarge multi-institutional datasets.

However, our model was constructed on the retrospectiveanalysis of prospectively recorded data from patients who re-ceived no preventive measures to avoid PAL (ie, sealants,buttressing material, and so forth), and the definition of PAL wasdifferent than the one used in Epithor (5 days in our cases, 7 daysin Epithor). These two differences could well explain the differ-ent performances of the model in the two studies. Besides, theytested the model on patients operated on in 2009, and it is wellknown that the performance of predictive models have to bechecked along in time to introduce improvements in the calcu-lation. To improve performance of the model, we would suggestthat the authors recalibrate it in their population by searchingfor new cutoffs for each factor.

Finally, in the Epithor cases, the coefficient for the variableforced expiratory volume in 1 second (FEV1) �80 is negative,meaning that patients with higher FEV1 had a higher probabilityof developing PAL, which usually is not expected. The reason forthis could be that surgeons treated cases differently with lowerFEV1 rendering the series not comparable with our cases.

There are advantages and disadvantages in using large multi-institutional databases compared with single institution data-bases for specific research projects. The major advantage is thepossibility to work on large numbers. On the other hand, somecritical variables may be difficult to control and define. Forinstance, in our study, the definition of pleural adhesions, whichis different from the one used in their testing of the modeladhesiolysis, was the presence of adhesions occupying an entirelobe or �30% of the lung surface. This definition was common inthe two centers as they share the same standardized datasetdefinitions. It seems unlikely that this term had the samestandardization across the nearly 100 French units, contributingto the Epithor.

In our opinion, a correct validation should be performed on anexternal series with the same definitions of outcome (PAL) andfactors.

We would be happy to cooperate in the design of a multi-institutional predictive model based on prospective homoge-neous cases and clearly defined variables.

Alessandro Brunelli, MDGonzalo Varela, MD

Division of Thoracic SurgeryOspedali Riuniti AnconaVia Conca 71Ancona 60020, Italye-mail: brunellialex@gmail.com

References

1. Bernard A, Rivera C, Falcoz PE, Vicaut E, Thomas P, DahanM. Application of model score of prolonged air leak in the

French database (letter). Ann Thorac Surg 2011;92:1548–50.

© 2011 by The Society of Thoracic SurgeonsPublished by Elsevier Inc

2. Brunelli A, Varela G, Refai M, et al. A scoring system topredict the risk of prolonged air leak after lobectomy. AnnThorac Surg 2010;90:204–9.

Reexpansion Pulmonary Edema After Large-VolumeThoracentesisTo the Editor:

In a previous study on the risk of reexpansion pulmonaryedema (RPE) after large-volume thoracentesis, Feller-Kopman and colleagues [1] reported that clinical RPE devel-oped in 1 of the 185 patients (0.5%) who underwent large-volume thoracentesis (�1 L). The incidence of RPE was notassociated with the volume of fluid removed, pleural pres-sure, or pleural elastance. They suggested that more than 1 Lof pleural fluid can be drained at 1 session. However, weencountered a case of severe RPE after large-volume thora-centesis in December 2010.

A 60-year-old man having hypertension, diabetes mellitus,and hepatitis B virus-related liver cirrhosis experienced short-ness of breath for 5 days. Left-sided pleural effusion was noted(Fig 1). Ultrasound-guided thoracentesis was performed, and1,120 mL of pleural fluid was removed without using negativesuction pressure. He did not experience chest discomfort duringthe procedure but developed pulmonary edema with respiratoryfailure, shock, and unconsciousness after 2 hours (Fig 2). He wasresuscitated and discharged 2 weeks later without any sequelae.

The amount of pleural fluid that can be removed at 1 sessionhas been a subject of debate because of the risk of RPE [1–3]. We

elieve that large-volume thoracentesis can be performed if it islinically indicated. The incidence of RPE after large-volumehoracentesis is low (�1%) [1, 4]. However, the mortality rate inuch patients may be as high as 20% [5]. We have reported ourase to remind others of this rare but possibly fatal complication.

Fig 1. Chest roentgenogram acquired before thoracentesis showing

left-sided pleural effusion.

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