Biomedical subjects

G S Linden

Publications and source records attributed to G S Linden.

4 recordsLinked to original sources

PubMed1984

Hemodynamics of patients with severe chronic obstructive pulmonary disease during progressive upright exercise.

This study evaluated the relationship between the oxygen consumption (VO2) and cardiac output and heart rate during progressive exercise in the upright position in 26 patients with severe chronic obstructive pulmonary disease. Forced expiratory volume in one second (FEV1) was 0.82 +/- 0.21 L, and single-breath carbon monoxide diffusing capacity was 39 +/- 20% predicted. Cardiac outputs were measured by the direct Fick method. The patients as a group had a normal cardiac output for the level of VO2. The mean pulmonary artery pressure in our patients (22.5 +/- 10.1 mmHg) was increased at rest; during exercise, it increased abnormally to 45.5 +/- 18.9 mmHg. The heart rates were increased both at rest and during exercise, and the increase in heart rate for an increase in VO2 was higher than normal. The relative tachycardia observed was probably related to a combination of abnormal arterial blood gases, concomitant bronchodilator administration, deconditioning, and right ventricular dysfunction. The relative tachycardia did not appear to have an adverse effect on exercise tolerance because the ratio of maximal exercise ventilation to the FEV1 exceeded 35 in those patients with observed maximal heart rates above 90% of predicted. The results of this study suggest that improvements in the exercise tolerance of these patients is dependent upon improving their ventilatory capabilities or the efficacy of their ventilation.

Aged↗

PubMed1984

Effects of digoxin on exercise capacity and right ventricular function during exercise in chronic airflow obstruction.

We evaluated 12 patients with stable chronic airflow obstruction (CAO) and no clinical evidence of left ventricular disease to determine the effects of oral digoxin on exercise capacity (VO2 max) and on right ventricular pump function during exercise. In this randomized, double blind, placebo controlled, cross-over study, patients performed exercise tests and underwent measurement of ejection fractions after two weeks of therapy with oral digoxin (0.25 mg/day) and after two weeks of placebo. Incremental upright exercise testing to a symptom-limited maximum was performed on a cycle ergometer. Right and left ventricular ejection fractions (RVEF, LVEF) were obtained in the supine position at rest and at approximately 75 percent of the maximum workload by gated equilibrium radionuclide angiography. All patients had abnormal right ventricular function, manifested either by a low resting RVEF (less than 45 percent) or a subnormal response to exercise (less than 5 percent increase). The small increases in RVEF with digoxin (mean +/- SE) at rest (44 +/- 5 vs 41 +/- 4 percent) and during exercise (46 +/- 4 vs 44 +/- 3 percent) did not achieve statistical significance. With digoxin, small increases in exercise duration (10.0 +/- 1.5 vs 9.0 +/- 1.4 min), maximum workload achieved (48 +/- 6 vs 42 +/- 5 W), VO2 max (0.85 +/- 0.06 vs 0.81 +/- 0.06 L/min), and oxygen-pulse (O2-P) (6.6 +/- 0.5 vs 6.3 +/- 0.4 ml/beat) occurred. Only the increase in O2-P was significant (p less than 0.05). From this study we conclude that digoxin does not significantly improve exercise capacity in severe chronic airflow obstruction with impaired right ventricular function, nor does it improve RVEF either at rest or during supine submaximal exercise.

Digoxin↗

PubMed1983

Effects of verapamil on pulmonary haemodynamics during hypoxaemia, at rest, and during exercise in patients with chronic obstructive pulmonary disease.

The haemodynamic effects of intravenous verapamil at rest, during hypoxaemia, and during progressive exercise were evaluated in 10 patients with chronic obstructive lung disease. Verapamil produced significant decreases in the peak heart rate and systemic blood pressure during exercise but exercise capacity and pulmonary gas exchange at exhaustion were unaffected. There were no significant changes in pulmonary artery pressure or total pulmonary vascular resistance during exercise or during the breathing of either air or a hypoxic gas mixture at rest. No clinically useful benefit was found with verapamil in the dosage used in this group of patients and the value of calcium antagonists in the treatment of patients with chronic obstructive lung disease requires further clarification.

Aged↗

PubMed1983

Prevention of suctioning-related arterial oxygen desaturation. Comparison of off-ventilator and on-ventilator suctioning.

The purpose of this study was to determine the frequency and severity of arterial oxygen desaturation during and after endotracheal suctioning in a group of ventilator-dependent patients with acute respiratory failure (the majority of whom had underlying obstructive lung disease) and to evaluate the efficacy of several maneuvers designed to minimize desaturation. The adaptor method presented obviates both removal from and reconnection to the ventilator during suctioning, as well as the need to alter ventilator settings. It is concluded that on-ventilator adaptor suctioning is a simple and effective measure for minimizing suctioning-related arterial oxygen desaturation.

Arteries↗