oa Cardiovascular Journal of Africa - Respiratory muscle function in chronic heart failure
We measured respiratory muscle function in 54 patients with heart failure and 45 normal subjects controlled for age, height and weight. All the patients were clinically examined for severity of heart failure using Boston criteria. Maximum inspiratory pressure (MIP) at residual volume (inspiratory muscle strength), and maximum expiratory pressure (MEP) at total lung capacity (expiratory muscle strength) were recorded in both groups according to the method of Black and Hyatt. Endurance was measured as the maximum voluntary ventilation (MVV) for 12 seconds. Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were also measured. The mean age of patients was 52.3 ï¿½ 13 and that of controls 50.8 ï¿½ 12.9 years. Results. The FVC was 73 ï¿½ 19.2 I (105 ï¿½ 17.7 in controls), the FEV1 as percentage of predicted 71 ï¿½ 22 (105 ï¿½ 18.5 in controls), the MIP 84.9 ï¿½ 29.3 cmH20 (113.3 ï¿½ 19.2 in controls), (P < 0.0001), the MEP 92.1 ï¿½ 25.1 cmH20 (106.4 ï¿½ 21.8 in controls (P < 0.004)), and the MVV 75.4 ï¿½ 27.41 (117.9 ï¿½ 20.6 in controls) (P < 0.0001). Boston criteria as a measurement of clinical severity were inversely correlated with MVV (r = -0.70; P < 0.001), MIP (r = 0.65; P < 0.001) and MEP (r = - 0.37; P < 0.01). Conclusion. Heart failure significantly reduces respiratory muscle strength and endurance.
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