Thoracoscopic laser ablation of pulmonary bullae. Radiographic selection and treatment response.

The purpose of this study was to develop objective preoperative selection methods for predicting outcome in patients undergoing thoracoscopic laser ablation of emphysematous pulmonary bullae. Initial radiographic presentation was correlated with physiologic function both before and after the operation in 24 patients entered into a prospective clinical protocol for evaluation of carbon dioxide laser treatment of emphysematous pulmonary bullae. Nineteen surviving patients underwent follow-up evaluation 1 to 3 months after the operation. Pulmonary function test results showed improvements in spirometry (forced vital capacity increased 0.82 +/- 0.125 L, forced expiratory volume in 1 second increased 0.36 +/- 0.07 L, and maximum voluntary ventilation increased 11.69 +/- 2.6 L/m; p < 0.002); airway resistance decreased by 0.9 +/- 0.35 cm of water/L per second, and specific conductance increased 0.019 +/- 0.006 L/cm H2O per second (p < 0.02). Lung volumes improved (residual volume decreased 1.25 +/- 0.23 L, p < 0.001) without significant change in resting gas exchange. Quantitative radiographic grading of extent of preoperative pulmonary bullae correlated well with response to laser treatment in patients with preoperative and postoperative studies. Patients with large bullae accompanied by crowding of adjacent lung structures, upper lobe predominance, and minimal underlying emphysema had greatest improvement in pulmonary function results with laser bullae ablation (p < 0.05). However, some patients with multiple smaller bullae and diffuse emphysema also demonstrated objective improvement after operation. Quantitative radiographic analysis of the extent of bullous disease and the degree of associated emphysema can be used to determine short-term postoperative pulmonary response and may be useful in selecting future thoracoscopic laser bullae ablation candidates. Additional follow-up will be necessary to further improve selection criteria and help define the long-term role of thoracoscopic laser treatment of bullous emphysema.

Video-thoracic surgery for treatment of end-stage bullous emphysema and chronic obstructive pulmonary disease.

Surgical treatment of emphysema and chronic obstructive pulmonary disease (COPD) has received renewed attention because of advances in instrumentation and techniques. Our approach includes video-assisted thoracotomy, neodymium-Yag and KTP laser plication of emphysematous bullae, pulmonary resection using reinforced stapling, and pleurodesis: reduction pneumonoplasty. In a 9-month period, 28 patients (age 52 to 78, 23 men and 5 women) with end-stage disease underwent reduction pneumonoplasty. Oxygen therapy was required in 82 per cent, steroid therapy was used in 86 per cent, and the preoperative FEV1 averaged 0.68 +/- 0.05. The most severely diseased lung was determined by physical, chest film, and CT scan, and this lung had reduction pneumonoplasty. There were no hospital mortalities. Prolonged postoperative air leaks occurred in 42 per cent of patients. Postoperatively FEV1 was 0.91 +/- 0.35. Lung size (chest film) showed 21.6 per cent reduction in volume. Subjective improvement was noted in 78.6 per cent (22/28) of patients, and no patient reported worse symptoms. Half of the steroid-using patients required a reduced steroid dose or no steroid therapy, and 5/23 (21.7%) patients had reduced oxygen requirements. Reduction pneumonoplasty can improve the symptoms of severe emphysema and COPD. Our results with treatment of one lung suggest that further improvement may be anticipated by proceeding with surgery for the contralateral lung.

Effect of exercise on mouth-to-cecum transit in trained athletes: a case against the role of runners' abdominal bouncing.

The role of exercise on the gastrointestinal motor function and in particular on transit time is a matter of hard debate. Numerous studies in the past have failed to demonstrate a consistent effect of short term exercise on transit time in untrained subjects and trained athletes. It has been, however, suggested that running, with its constant jostling of the abdomen, may have a different effect than exercise performed in a stationary setting. To examine the effect of running on gastrointestinal transit time, 8 healthy male trained runners ingested a lactulose meal and assigned to rest or exercise on separate days. Exercise consisted of running 9.6 km in an hour, while exhaled gas was sampled every 10 minutes for volume, minute ventilation and hydrogen concentration. The mean O2 consumption was 36.8 ml/min/kg during exercise session and 4.7 ml/min/kg during rest period. Post lactulose rise in hydrogen concentration occurred at a mean of 85 +/- 25.1 and 84 +/- 18.1 minutes for resting and exercise sessions respectively (p = 0.732). On the basis of the present data we conclude that (1) mouth-to-cecum transit time is not affected by short term intense exercise in trained athletes; (2) that bouncing of the abdominal content in case of running probably does not change the transit time; and finally, (3) the impact of moderate to intense short term exercise on the mouth-to-cecum transit is not influenced by the subject's fitness state.

Mechanisms of expiratory valves resistance.

Expiratory valves are the major source of resistance in ventilator circuits. Some valves, particularly under certain conditions, cause high resistances. To establish the mechanisms of expiratory valve resistance (R), we measured R of 4 commercial valves under several experimental conditions. The pressure above the diaphragm of one of the valves was also measured. The results reveal that all valves produce significant resistance to air outflow. This resistance is the result of the physical and functional interplay of several valve components. (1) In most valves, the dimensions of the air pathway through the valve contribute minimally to resistance in spite of its tortuosity. (2) The diaphragm adds a major contribution to valve resistance particularly at low flows. The diaphragm effect has 2 components: its weight--a gravity-dependent, fixed effect most predominant at very low flows and evident in all the valves--and a spring-like effect--a component related to the resistance of the diaphragm to deformation and of variable magnitude in different valves. Because of diaphragm-related components at low flows, valves behave as variable threshold resistors. (3) There is limitation to air egress from above the diaphragm at higher exhaled flows, which further contributes to valve resistance. The first and last components cause the valves to function also as flow resistors. Constant flows effectively counteract the diaphragm spring-like effect. Measuring valve resistance during constant flow underestimates the resistance that occurs under dynamic flow conditions characteristic of clinical situations.

Inhibin and gonadotrophin secretion in physically active males after acute exercise.

Serum concentrations of luteinizing hormone (LH) follicle stimulating hormone (FSH), testosterone and inhibin were measured in six physically active male volunteers after heavy exercise on a treadmill. Hormone measurements were made before exercise, immediately after exercise and at 30-min intervals for 3 h after exercise. Serum concentrations of LH fell after exercise reaching nadir values between 60 and 180 min post-exercise. The nadir value of LH for the group as a whole occurred 90 min after exercise. Serum testosterone concentrations paralleled the changes in LH concentrations. Serum FSH and inhibin concentrations did not show any appreciable change from baseline values. The data suggest that acute exercise does not significantly lower serum concentrations of FSH or inhibin. Whether repetitive and prolonged heavy exercise, as in competitive runners, produces alterations in serum inhibin concentrations remains to be determined.

Tidal breath flow-volume curves in obstructive sleep apnea.

Because of the gravitational position during sleep and the associated relaxed state, we hypothesized that passive expiration in the supine position might reflect upper airway pathophysiology in obstructive sleep apnea (OSA). We prospectively enrolled and tested 92 subjects with several clinical conditions. Maximal comfort and relaxation during expiration was achieved by connecting subjects to a ventilator via a mouthpiece. An initial respiratory rate of 16 breaths/min and tidal volume of 10 ml/kg were selected. Fine adjustments were then made to achieve maximal subject relaxation. Using this method, we obtained reproducible tidal breath flow-volume curves (TBFVC). Testing was performed in both sitting and supine positions. Standard pulmonary function tests, including spirometry and lung volume measurements, were also obtained in both sitting and supine positions. Of 86 patients who could be evaluated, 12 (60%) of 20 subjects with documented OSA (respiratory disturbance index: mean, 64.8; range, 10 to 120.5) demonstrated a positional change in the terminal portion of the TBFVC; 10 (32%) of 31 with a history of snoring also tested positive, but only three (9%) of 35 subjects with no OSA, by polysomnography (n = 8) or questionnaire (n = 27), demonstrated such a positional change. This positional change in TBFVC, which was significantly more frequent in subjects with OSA, could not be attributed to any measurable pulmonary function abnormality or body mass index. We believe this positional change in TBFVC reflects upper airway functional narrowing induced by assumption of supine position and decreasing airflow rates.

Thoracoscopic carbon dioxide laser treatment of bullous emphysema.

A new technique of thoracoscopic laser ablation of pulmonary bullae suitable for patients with multiple bullae and diffuse emphysema was developed and assessed in 22 patients. 20 of 22 patients survived. Pre-operative and postoperative functional evaluation is available for the 11 patients followed up for more than a month; at 1 to 3 months postoperatively there were increases in FVC (mean 2.0 litres pre-operatively to 2.7 litres postoperatively, p less than 0.001), in FEV1 (0.74 to 1.06 litres, p = 0.01), and in maximum exercise treadmill times (5.4 min to 8.0 min, p less than 0.01). Postoperative air leaks lasted a mean of 13 days and usually resolved spontaneously. Other complications were bleeding (1 patient) and unilateral acute lung injury (1 patient). These results suggest that selected patients with diffuse emphysema and pulmonary bullae may benefit from thoracoscopic carbon dioxide laser ablation.