Impact of pectus excavatum on pulmonary function before and after repair with the Nuss procedure

Presented at the 35th Annual Meeting of the American Pediatric Surgical Association, Ponte Vedra, Florida, May 27-30, 2004.
https://doi.org/10.1016/j.jpedsurg.2004.09.040Get rights and content

Abstract

Background/Purpose

Patient reports of preoperative exercise intolerance and improvement after surgical repair of pectus excavatum (Pex) have been documented but not substantiated in laboratory studies. This may be because no study has been large enough to determine if pulmonary function tests (PFTs) in the Pex population are significantly different from the normal population, and none has assessed improvement in pulmonary function after Nuss bar removal.

Methods

The authors studied PFT results in 408 Pex patients before repair and in a subset of 45 patients after Nuss procedure and bar removal. Significance of differences in percent predicted (using Knudson's equations) was tested using t tests (parametric) or sign tests (nonparametric). Normal was defined as 100% of predicted for forced vital capacity (FVC), forced expired volume in 1 second (FEV1), and forced expiratory flow (FEF25%-75%).

Results

Preoperatively, FVC and FEV1 medians were lower than the normal by 13%, whereas the FEF25-75 median was lower than normal by 20% (all P < .01). The postoperative group had statistically significant improvement after surgery for all parameters. Patients older than 11 years at the time of surgery had lower preoperative values and larger mean post–bar removal improvement than the younger patients. An older patient with a preoperative FEF25-75 score of 80% of normal would be predicted by these data to have a postoperative FEF25-75 of 97%, indicating almost complete normalization for this function.

Conclusions

These results demonstrate that preoperatively Pex patients as a group have decreased lung function relative to normal patients. After Nuss procedure and bar removal, we show a small but significant improvement in pulmonary function. These results are consistent with patient reports of clinical improvement and indicate the need for more in-depth tests of cardiopulmonary function under exercise conditions to elucidate the mechanism.

Introduction

Pectus excavatum (Pex) is a birth defect that results in a depression of the sternum and anterior chest. The size and shape of the depression range from mild concave depressions of a few millimeters to severe asymmetrical depressions of several centimeters. Most patients with more than mild Pex have displacement of the lungs and heart, and many report some degree of exercise intolerance or lack of endurance [1], [2]. These patients tend to be round shouldered and have what physicians familiar with this disorder sometimes refer to as the classic pectus posture. In patients with severe depressions, there is clinical evidence that cardiorespiratory function may be impaired. This is usually manifested at the clinical level by mild to moderate exercise intolerance, chest pain with exertion, and recurrent respiratory tract infections [2] and at the laboratory level by decreased pulmonary function and stroke volume [3]. Nevertheless, questions remain about the impact of Pex on pulmonary function and the use of pulmonary function tests (PFTs) in assessing clinical outcomes in patients with Pex. Several factors may account for the apparently contradictory results in the literature including variability of the severity, the extent and nature of the surgical correction, and the age and small number of subjects studied.

After introduction of a minimally invasive procedure for Pex repair by the surgeons in our hospital, we have had a large influx of patients with Pex, many of whom have now had bar removal. We recently reported the results of a pre- and postsurgical survey of 19 patients in which patients and their parents reported significantly improved exercise tolerance after surgical repair of Pex with the Nuss procedure [4]. Patients further reported a decreased incidence of shortness of breath, chest pain, and tiredness. The purpose of the present investigation was to use more objective pulmonary function data from before and after treatment with the Nuss procedure to test the hypotheses that (1) patients with Pex who qualified for surgery (n = 408) have reduced PFTs relative to the normal population and (2) Pex repair results in significant improvement in PFTs after minimally invasive surgical intervention (Nuss procedure) and bar removal (n = 45).

Section snippets

Study population

We examined preoperative repair PFT results from 408 patients who were clinically approved for surgery at Children's Hospital of The King's Daughters (CHKD) in Norfolk, Va, between 1993 and 2003. The population was predominantly male (82%) and white (94%). The median age on the day of the PFT was 13.4 (interquartile range [IQR] 10.0,15.7). Marfanoid characteristics were noted by the surgeon in 24% of the patients, some degree of scoliosis was noted in 28%, and 39% self-reported frequent

Results

Table 1 shows the FVC, FEV1, and FEF25-75 results for the preoperative Pex population. For all 3 parameters, the population was significantly skewed away from normal, as illustrated by the P value in the last column. The 75th percentile for each parameter was below 100%, where in a normal population the 50th percentile would be expected to be near 100% and the 75th percentile would be expected to be above 100%. Tests of location confirm that the population average is significantly different

Discussion

Despite numerous studies of cardiac and pulmonary function in the laboratory over a 50-year period [3], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17] there continues to be uncertainty as to whether the Pex anomaly results in cardiopulmonary abnormalities. Several authors have noted decreases in pulmonary function (primarily vital capacity and airflow rate) among patients with Pex, although the results often fall within the normal range [15], [16], [17], [18]. These findings are

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