Chest
Volume 98, Issue 5, November 1990, Pages 1091-1094
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Respiratory Muscle Strength in Congestive Heart Failure

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In experimental animals, conditions which drastically decrease cardiac output may reduce the strength and endurance of respiratory muscles leading to hypercapnic respiratory failure. Because patients with chronic CHF have reduced cardiac output and vital capacity (FVC), we measured Pimax and PEmax and maximal handgrip force in 16 patients with CHF and 18 AMNs. The patients with CHF had a mean left ventricular ejection fraction of 26±7 percent. Maximal respiratory pressures were significantly reduced; group mean values (± SD) for Pimax at FRC were 41.4±5.6 cm H2O (CHF) and 102.1±27.4 cm H2O (AMN) (p<0.001), with Pimax values in five patients with CHF as low as 20 to 30 cm H2O. In most patients, PEmax was comparably reduced. Handgrip force was less dramatically reduced, suggesting selective respiratory muscle weakness. Possible explanations include reduction in respiratory muscle blood flow or generalized muscular atrophy and weakness related to cardiac cachexia.

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Patients

Sixteen ambulatory outpatients with severe chronic CHF were studied, as were 18 AMNs (Table 1). Mean age (±SD) of the patients was 61±9 years, and that of the AMNs was 61±5 years. Ten patients had CAD, four had congestive ICM and one each had RhHD, IHSS, and had undergone mitral valve replacement. Of the ten patients with CAD, two had had coronary bypass surgery 12 and 13 years earlier. The mean LVEF by gated nuclear angiogram (MUGA) for the group with CHF was 26±7 percent; six of the 16 were

Results

Results are summarized in Tables 1 and 2. Both FVC and FEV1 were significantly reduced in the group with CHF, a fact attributable mostly to pulmonary congestion and edema. Although the subjects with CHF were mildly restricted, the FEVl/FVC% was not significantly different between the group with CHF and the normal group, attesting to the absence of significant coexisting obstructive pulmonary disease in the patients with CHF.

Handgrip strength was moderately reduced (31.5±6.4 kg) in the group

Discussion

We have shown that maximal static respiratory pressures were significantly decreased in a group of patients with severe biventricular CHF. In five patients (Table 1), Pimax values at FRC were between 20 and 30 cm HaO, low values which in a critical care setting could cause concern over whether a patient might require mechanical ventilation, yet these patients were ambulatory, although dyspneic. These observations suggest that many such patients may be functioning precariously close to

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Cited by (0)

Supported by the VA Research Service.

Manuscript received January 22; revision accepted May 1.

Associate Professor of Medicine.

Pulmonary Fellow.

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Professor of Medicine.

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Engineer, VA Research Service.

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