Assessment of Diaphragm Weakness

Abstract

Thirty patients with breathlessness and diaphragm weakness were studied by measuring transdiaphragmatic pressures during maximal inspirations to total lung capacity, maximal static inspiratory efforts from residual volume, and maximal sniffs from functional residual capacity. Maximal static respiratory mouth pressures were also recorded, and rib cage and abdominal movements were monitored with pairs of magnetometers. Sniff transdiaphragmatic pressure was abnormally low in all patients and was correlated with transdiaphragmatic pressure during other maneuvers, and with maximal static inspiratory mouth pressures. There was no relationship between the severity of dyspnea and transdiaphragmatic pressure in the group as a whole. The weakest patients had orthopnea and paradoxical inward inspiratory motion of the anterior abdominal wall; measurements suggested that at least 30 cm H2O transdiaphragmatic pressure was required to overcome the hydrostatic pressure of the abdominal contents. By contrast, patients with mild diaphragm weakness had neither orthopnea nor abdominal paradox. Thus, patients with breathlessness and diaphragm dysfunction may have varying degrees of diaphragm weakness that may be difficult to detect clinically; the diagnosis and quantification of diaphragm weakness requires the measurement of transdiaphragmatic pressure.

Test/Retest Reliability of Maximum Mouth Pressure Measurements With the MicroRPM in Healthy Volunteers

“…2 The importance of its assessment is represented by the fact that the findings from an appropriate evaluation of respiratory muscle strength may provide insight into unexplained dyspnea and insufficient cough. 3 It is also useful as a complementary outcome measure for many disorders, 4 such as neuromuscular disorders, 5 COPD, 6 and heart failure. 7 These reasons have strengthened the need to extensively research the development of reliable manometers for measuring respiratory muscle strength.…”

Postoperative Phrenic Nerve Palsy, A Cause Of Prolonged Mechanical Ventilation In Trans-Sternal Thymectomy

“…Baseline upright vital capacity is mildly reduced (up to 80% of predicted). With bilateral disease, vital capacity may fall to 50% of predicted 18 . Maximal inspiratory pressures fall to 80% and 30% of predicted, with unilateral and bilateral paralysis, respectively 19 .…”

Diaphragmatic Paralysis - Symptoms, Evaluation, Therapy and Outcome

“…Baseline upright vital capacity is mildly reduced (up to 80% of predicted). With bilateral disease, vital capacity may fall to 50% of predicted (Mier-Jedrzejowicz et al, 1988). Maximal inspiratory pressures fall to 80 and 30% of predict, with unilateral and bilateral paralysis, respectively (Steier et al, 2007).…”