Lung function in fire fighters.

Lung function tests were performed on 49 fire fighters of the city of New Haven. Their mean age was 36.4 years, with a mean of 11.7 years as fire fighters. The lung function tests were compared to a control group with a mean age of 33.4 years. There was no significant difference between the mean normal pulmonary function tests of the fire fighters and the control group. The results showed that in this group of fire fighters long-term occupational exposure was not associated with pulmonary function abnormalities.

Bilateral diaphragmatic paralysis: clinical spectrum, prognosis, and diagnostic approach.

In a retrospective review of the clinical course of five patients with nontrauma-related bilateral diaphragmatic paralysis, we found that the diagnosis is generally delayed (median delay: two years) in the presence of moderate to severe respiratory insufficiencies. Orthopnea out of proportion to the underlying cardiopulmonary status and thoracoabdominal paradoxus in the supine position are the clues to the diagnosis. Pulmonary function tests showed a typical restrictive ventilatory defect, and arterial blood gas showed chronic respiratory acidosis. Failure to recognize the diaphragmatic impairment led to cardiopulmonary decompensations such as cor pulmonale and acute respiratory failure. However, with the institution of appropriate therapy, adverse effects resolved and all five patients are alive and continue to lead independent lives. We conclude that nontrauma-related bilateral diaphragmatic paralysis is an underrecognized and underdiagnosed condition. The results also indicate that early diagnosis and treatment can minimize morbidity and mortality, and that excellent long-term, good-quality survival can be expected.

Terbutaline and diaphragm function in chronic obstructive pulmonary disease: a double-blind randomized clinical trial.

We conducted a double-blind, randomized crossover trial to evaluate whether oral terbutaline (2.5 mg orally three times daily for a week) increased the force of diaphragmatic contraction in normocapnic patients with chronic obstructive pulmonary disease. Ten patients with moderate to severe airway obstruction completed the trail. Compared with placebo, terbutaline produced a mean increase of 5.8 cmH2O in peak inspiratory mouth pressure and a mean increase of 5.0 cmH2O in transdiaphragmatic pressure during a maximal inspiratory manoeuvre. These small changes with terbutaline failed to achieve statistical significance. Also, terbutaline failed to alter flow rates (FEV1, Vmax50) or patients' dyspnoea ratings using two separate clinical scales (Pneumoconiosis Research Unit Score and the Modified Dyspnoea Index). Because all observed changes in respiratory muscle strength were small and because the trial had power to detect small changes in inspiratory mouth pressures, we suggest that oral terbutaline at the dose administered in this study has little noteworthy effect on respiratory muscle strength in normocapnic patients with chronic obstructive pulmonary disease.

Diaphragmatic dysfunction in siblings with hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease).

Hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease) is characterized by chronic degeneration of peripheral nerves and roots, resulting in distal muscle atrophy, beginning in the feet and legs and later involving the hands. The association of this disease with diaphragmatic dysfunction has not been reported. We studied a patient with hereditary motor and sensory neuropathy type 1 (Charcot-Marie-Tooth disease) and type 2 diabetes mellitus who had severe diaphragmatic impairment. Some of the clinical findings are similar to the sleep apnea syndrome, which could lead to incorrect diagnosis and delay in the administration of appropriate therapy. Transdiaphragmatic pressure studies on the subject's brother, who also has Charcot-Marie-Tooth disease and type 2 diabetes mellitus, revealed subclinical impairment of diaphragmatic function. These findings suggest that phrenic nerve involvement may be part of the spectrum of polyneuropathy in Charcot-Marie-Tooth disease in association with diabetes mellitus.

Acute effects of passive smoking on lung function and airway reactivity in asthmatic subjects.

We studied the acute effects of one hour of passive cigarette smoking on the lung function and airway reactivity of nine young adult asthmatic volunteers. At the time of this study, the subjects were asymptomatic and had normal or nearly normal lung function. Passive smoking produced no change in expiratory flow rates. However, there was a small decrease in nonspecific bronchial reactivity, as assessed by methacholine inhalation challenge testing (p = 0.022). Pharmacologically active substances present in cigarette smoke, such as nicotine, may explain the observed change in airway reactivity. Although the finding of decreased airway reactivity might suggest that passive smoking produces a "protective" effect on the underlying asthma, the observed change in reactivity was slight and of uncertain clinical significance. We conclude that passive smoking presents no acute respiratory risk to young asymptomatic asthmatic patients.

Rabbit lung after acute smoke inhalation. Cellular responses and scanning electron microscopy.

The cellular responses in the lungs of rabbits and the morphologic features of the tracheobronchial tree by scanning electron microscopy were examined 24 hours following acute inhalation of Douglas fir wood smoke. Thermal injury to the upper airway was excluded. Injury to proximal tracheal lining cells was severe and consisted of loss of the epithelium. The changes of the epithelial barrier in the proximal major bronchi were less severe in nature. However, the alterations observed by scanning electron microscopy suggested dysfunction of the mucociliary blanket. Both cell counts of bronchoalveolar lavage fluid and morphologic findings reflected an increase in alveolar macrophage response. Smoke-exposed alveolar macrophages showed significant changes in the surface features. These findings may explain the tracheobronchitis seen clinically, and the propensity of patients to lung infection following smoke inhalation.

Positional dyspnea and oxygen desaturation related to carcinoma of the lung. Up with the good lung.

Body position can lead to respiratory symptoms and affect gas exchange in disease states. We describe a patient with carcinoma of the left lung in whom dyspnea and oxygen desaturation developed in the right lateral position only. Fiberoptic bronchoscopic study demonstrated a tumor mass protruding into the left main-stem bronchus, which caused further narrowing when the patient turned on his right side.

Respiratory muscle fatigue after marathon running.

Respiratory muscle fatigue has been demonstrated in the laboratory as well as in pathological states, but whether it occurs in healthy individuals under physiological conditions is unknown. To determine whether fatigue of the respiratory muscles may develop with endurance exercise, we measured spirometry and respiratory muscle strength and endurance in four runners before and after completion of a marathon race (42.2 km). Strength was assessed by measuring maximal inspiratory (PImax) and expiratory (PEmax) pressures and transdiaphragmatic pressure during inspiratory capacity (PdiIC); endurance was determined by measuring maximal voluntary ventilation (MVV). After marathon running (mean time, 3 h 24 min) there was no change in forced vital capacity, inspiratory capacity, or flow rates from prerace values. Decreases were observed between pre- and postrace PImax (165.8 +/- 11.0 vs. 138.5 +/- 7.6 cmH2O; P less than 0.01) PEmax (240.0 +/- 20.4 vs. 173.0 +/- 22.6 cmH2O; P less than 0.05), PdiIC (78.8 +/- 11.6 vs. 63.3 +/- 7.0 cmH2O; P less than 0.10), and MVV (178 +/- 24.2 vs. 161.2 +/- 23.2 l/min; P less than 0.005). The decrements in respiratory muscle strength and endurance suggest the development of respiratory muscle fatigue after marathon running.