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NewsletterLiterature Reviews Body weight and nutritional changes after reduction pneumoplasty for severe emphysema: A randomized study T C Mineo, V Ambrogi, E Pompeo, P Bollero, D
Mineo, I Nofroni. J Thorac Cardiovasc Surg 2002; 124: 660-667
Background: The exact mechanism of weight loss and malnutrition in patients with emphysema is not known. Several hypotheses have been put forth including chronic bronchial infection, loss of muscle strength associated with aging, inactivity and steroid administration.1, 2 Creutzberg and colleagues3 identified a group of patients without response to high energy nutrition and hypothesized a multifactorial mechanism including anorexia, shift in body water compartments, inflammatory mediators and hypoxia. One of the more likely explanations could be the elevated oxygen cost of breathing which might be sustained by lung hyperinflation and loss in elastic lung recoil causing an unfavorable length-tension relationship in the respiratory muscles. In recent years reduction pneumoplasty (RP) has been shown to improve lung function, exercise capacity and subjective dyspnea in properly selected patients with COPD.4 The authors have already shown in a previous study that sole RP is superior to respiratory rehabilitation (RR) in improving lung function and exercise capacity.5 They have since studied in the same series of patients, the impact of RP compared to maximal medical therapy including RR on body weight and nutritional status. Methods: Patient Selection: 60 patients with severe emphysema who met 16 general inclusion criteria were enrolled in the study, which was designed as a prospective, randomized, controlled study of 6 months duration. The duration was chosen on the assumption that for either treatment, peak improvement should be attained within that time which was still limited enough to allow crossover of patients without improvement, to the most effective therapy. Written informed consent approved by the local IRB was obtained and 30 patients were randomly assigned to receive video-assisted thoracoscopic reduction pneumoplasty without respiratory rehabilitation and 30 patients were assigned to receive a structured, supervised, exercise respiratory rehabilitation program for a minimum of 6 weeks. Preoperative Assessment: Lung function assessment included ABG, plethysmography, spirometry, diffusion capacity and perfusion scan. Respiratory muscle strength was assessed by measurement of maximal inspiratory pressure at RV and maximal expiratory pressure at TLC. Digital chest radiographs and high resolution and volumetric helical CTs of the chest were done in all patients to assess emphysematous morphology. Exercise tolerance was assessed by standard 6 min walk test and treadmill test according to modified Bruce protocol. Dyspnea was rated according to the modified Medical Research Council score.6 All data were collected again at 3 and 6 months after completion of treatment. Quality of life was assessed with the 36-item Short Form Health-Related Questionnaire. Nutritional Assessment: This included dietary history, physical examination, anthropometric measurements which included height, weight, midarm circumference and triceps skin fold thickness and biochemical measurements including total protein, albumin, calcium, magnesium, phosphate, transferrin and cholesterol. Body composition was measured by 5-frequency bioelectric impedance analysis with the patient fasting, relaxed and lying supine. Fat mass (FM) and fat-free mass (FFM) were calculated by the conduction of an electric current through the body according to the software Impedenziometria Plus. Nutritional assessment was repeated at 3 and 6 months and if possible at 12 months. Surgical Technique: The surgery was directed towards reducing 20-30% of the lung volume by excising functionally useless and hyperinflated lung tissue. Patients assigned to the surgical arm of the study underwent tailored unilateral or bilateral RP. The main indication for unilateral RP was an asymmetric distribution of emphysema. Respiratory Rehabilitation: The outpatient program was directed towards optimizing the ability to perform daily activities by improving exercise capacity. It entailed 3-hour sessions, 5 days a week for 6 weeks. The first half of each session involved educational activities such as breathing retraining, nutritional and medication education and the second half, physical conditioning including respiratory exercises. Results: There was no difference in demographics, pulmonary function, nutritional status and anthropometric measurements between the patients in the two groups. 17 patients had bilateral and 13 had unilateral RP. 28 patients (2 died) in the RP group and 27 (2 withdrew and 1 died) in the RR group completed the 6-month study. 1-month morbidity as would be expected was significantly higher in the RP group whereas fatal and non-fatal complications were higher in the RR group. RP group had 2 late deaths (between 8 and 23 months) and the RR group had 4 (between 7 and 41 months). 12 patients in the RR group crossed over to surgical treatment. At 6 months the RP group scored significantly better in all parameters except maximal inspiratory pressure at RV, maximal expiratory pressure at TLC and PaCO2 in which the improvements were not statistically significant. With no significant difference in energy intake, body weight increased in the RP group with both FM and FFM increasing, although only FFM showed a significance. The gain in weight was 2.87 +/- 3.76 kg at 6 months (-1.11 +/- 2.64 kg in the RR group) and at 12 months all but 5 patients showed a weight gain with a mean change of 3.29 +/- 4.01 kg (-0.95 +/-1.9 kg in the RR group). This gain correlated significantly with low baseline weight and BMI. In the RP group, there was no difference in the weight gain, or the number of patients demonstrating a weight gain in the groups that underwent unilateral or bilateral surgery. The RP group showed statistically significant improvements in all indices except FM, blood glucose and total proteins. Weight gain in patients after was linearly correlated with reduction in RV. Discussion: Surgical treatment for emphysema must be individualized, because no criteria exist for predicting which patients will benefit from resection. Lung volume reduction surgery attempts to remove severely diseased areas of the lung, while allowing the remaining lung to expand better by decreasing hyperinflation and allowing the bronchioles to expand their diameter, giving improved elastic recoil with improved aeration and perfusion of the remaining lung. In the previous study by these authors, on the same patient population, it was found that the dyspnea index, PaO2 and exercise capacity improved after both RP and RR whereas pulmonary function and oxygen requirement improved only after RP. Two recent randomized studies 7, 8 have demonstrated immediate improvement of static volumes and quality of life after RP that is more prolonged than any benefit from RR. The improvements might be due to reduced thoracic hyperinflation and better lung volume expansion, both of which are related to a decrease in RV, which might explain the better results after RP. No significant differences in energy intake and diet composition were found between the 2 groups in this study, thus supporting the theory of an increased energy cost in patients with emphysematous, hyperinflated lungs who can regain weight after RP. These authors shed new light on explaining one of the important findings following reduction pneumoplasty.
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