Effects of lobectomy on lung function.

161

Advances in operative technique and perioperative care have considerably reduced surgical morbidity and mortality after pulmonary resections. Various single and combined parameters of functional operability have been proposed to assess the surgical risk. Pulmonary function tests adequately assess the pulmonary risk, and baseline or stress electrocardiography, echocardiography and nuclear cardiac studies assess the cardiac risk.Patients with normal or only slightly impaired pulmonary function (forced expiratory volume in one second (FEV1) and transfer factor of the lung for carbon monoxide (TL,CO) ≥80% of predicted) and no cardiovascular risk factors can undergo pulmonary resections up to a pneumonectomy without further investigation. For others, exercise testing, pulmonary split-function studies, or a combination of these two methods are recommended. Exercise testing, most frequently performed as a symptom-limited test with the measurement of maximal oxygen uptake (V 'O 2 ,max), assesses both the pulmonary and cardiovascular reserves. A V'O 2 ,max of <10 mL·kg -1 ·min -1 is generally considered prohibitive for any resection, a value of >20 mL·kg -1 ·min -1 or >75% of predicted normal, safe for major resections. Split-function studies are radionuclide-based estimations of the predicted postoperative (ppo) values of various parameters. The currently used ppo-parameters are FEV1-ppo, TL,CO-ppo and, most recently, V'O 2 ,max-ppo. Suggested cutoff values for safe resection are: for FEV1-ppo and TL,CO-ppo ≥40% pred; and for V 'O 2 ,max ≥35% pred, combined with an absolute value of ≥10 mL·kg -1 ·min -1 . The lowest acceptable ppo-values will still have to be established by additional prospective studies.In the long-term, resections involving not more than one lobe usually lead to an early functional deficit followed by later recovery. The permanent functional loss in pulmonary function is small (≤10%) and exercise capacity is only slightly reduced or not at all. Pneumonectomy, on the other hand, leads to an early permanent loss of about 33% in pulmonary function and 20% in exercise capacity. Thus, pulmonary function tests alone overestimate the functional loss after lung resection. Eur Respir J 1998; 11: 198-212 The dramatic increase in the incidence of bronchogenic carcinoma has made this disease the most frequent malignancy worldwide. In industrialized nations, the majority of lung resection candidates suffer from bronchogenic carcinoma, whereas only some decades ago benign conditions, such as destroyed lung parenchyma after tuberculosis, had to be removed. The prognosis of bronchogenic carcinoma remains sombre as about 75-85% are inoperable at the time of diagnosis [1], and despite recent advances in chemo-and radiotherapy regimens, surgical resection remains the only curative form of treatment [2].Depending on their extent, pulmonary resections lead to permanent loss of pulmonary function. In healthy people, resections up to a pneumonectomy are tolerated remarkably well. Lung cancer patients, however, are...

Section: Effect Of Lung Resection On Postoperative Pulmonary Functionmentioning

confidence: 99%

Functional evaluation of the lung resection candidate

Bolliger¹,

Perruchoud²

1998

161

“…Various studies have investigated the functional loss after lung resection in terms of pulmonary function tests (PFT) [2][3][4][5][6][7][8][9][10]. It is generally accepted that resections involving not more than one lobe lead to an early loss in PFT with later recovery and little permanent deficit, whereas pneumonectomies cause a bigger permanent functional loss [7,10].…”

mentioning

confidence: 99%

Pulmonary function and exercise capacity after lung resection

Bolliger¹,

Jordan²,

Solèr³

et al. 1996

194

131

The influence of pulmonary resection on functional capacity can be assessed in different ways. The aim of this study was to compare the effect of lobectomy and pneumonectomy on pulmonary function tests (PFT), exercise capacity and perception of symptoms.Sixty eight patients underwent functional assessment with PFT and exercise testing before (Preop), and 3 and 6 months after lung resection. In 50 (36 males and 14 females; mean age 61 yrs) a lobectomy was performed and in 18 (13 males and 5 females; mean age 59 yrs) a pneumonectomy was performed.Three months after lobectomy, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), total lung capacity (TLC), transfer factor of the lungs for carbon monoxide (TL,CO) and maximal oxygen uptake (V'O 2 ,max) were significantly lower than Preop values, increasing significantly from 3 to 6 months after resection. Three months after pneumonectomy, all parameters were significantly lower than Preop values and significantly lower than postlobectomy values and did not recover from 3 to 6 months after resection. At 6 months after resection significant deficits persisted in comparison with Preop: for FVC 7% and 36%, FEV1 9% and 34%, TLC 10% and 33% for lobectomy and pneumonectomy, respectively; and V'O 2 ,max 20% after pneumonectomy only. Exercise was limited by leg muscle fatigue in 53% of all patients at Preop. This was not altered by lobectomy, but there was a switch to dyspnoea as the limiting factor after pneumonectomy (61% of patients at 3 months and 50% at 6 months after resection). Furthermore, pneumonectomy compared to lobectomy led to a significantly smaller breathing reserve (mean±SD) (28±13 vs 37±16% at 3 months; and 24±11% vs 33±12% at 6 months post resection) and lower arterial oxygen tension at peak exercise 10.1±1.5 vs 11.5±1.6 kPa (76±11 vs 86±12 mmHg) at 3 months; 10.1±1.3 vs 11.3±1.6 kPa (76±10 vs 85±12 mmHg) at 6 months postresection.We conclude that measurements of conventional pulmonary function tests alone overestimate the decrease in functional capacity after lung resection. Exercise capacity after lobectomy is unchanged, whereas pneumonectomy leads to a 20% decrease, probably due to the reduced area of gas exchange.

“…As the reduction in TLC puts the inspiratory muscles at a mechanical advantage, the absence of increase in PL,st,TLC would imply either a decreased inspiratory muscle strength, or a decreased chest wall compliance after LVRS. Similarly, the shift rightwards and downwards of the P-V curve also reported after LVRS, with volume expressed in absolute terms [66,71] or in per cent predicted TLC [67], is a usual feature after lung resection [73]. This shift would be more relevant if it was shown to occur with volume expressed as a percentage of actual TLC.…”

Section: Static Mechanics Of the Respiratory Systemmentioning

confidence: 98%

Physiological basis of improvement after lung volume reduction surgery for severe emphysema: where are we?

Marchand¹,

Gayan‐Ramirez²,

Leyn³

et al. 1999

Physiological basis of improvement after lung volume reduction surgery for severe emphysema: where are we? E. Marchand, G. Gayan-Ramirez, P. De Leyn, M. Decramer. #ERJ Journals Ltd 1999. ABSTRACT: Lung volume reduction surgery has become an accepted therapeutic option to relieve the symptoms of selected patients with severe emphysema. In a majority of these patients, it causes objective as well as subjective functional improvement. A proper understanding of the physiological determinants underlying these beneficial effects appears very important in order to better select patients for the procedure that is currently largely carried out on an empirical basis.Lung volume reduction surgery has two distinct effects. Firstly, it causes an increased elastic recoil, which at least partially explains the enhanced maximal expiratory flow. Secondly, it is associated with a reduction of hyperinflation which allows for an increase in global inspiratory muscle strength and in diaphragmatic contribution to tidal volume as well as a decrease in the inspiratory elastic load imposed by the chest wall. Taken together, these effects result in a reduced work of breathing and in an enhanced maximal ventilation which both contribute to the increased exercise capacity and reduced dyspnoea after surgery. The improved lung recoil and the reduced hyperinflation after volume reduction surgery were the primary postulates upon which the usual selection criteria for the procedure were based. It is now likely that these are correct. Nevertheless, some patients do not benefit from lung volume reduction surgery and the current literature does not allow for a refinement of the selection process from a physiological point of view.The exact mechanisms underlying the improvement in lung recoil, lung mechanics, and respiratory muscle function remain incompletely understood. Moreover, the effects of lung volume reduction surgery on gas exchange and pulmonary haemodynamics still need to be more fully investigated. An analysis of the characteristics of patients who do not benefit from the procedure and the development of an animal model for lung volume reduction surgery would probably help address these important issues. Eur Respir J 1999; 13: 686±696.