Horváth, Tamás

Background: The breathing cycle consists of abdominal breathing (AB), for which the diaphragm is responsible, and thoracic breathing (TB), generated by the intercostal muscles. Contraction of the two portions of the diaphragm accounts for 80% percent of inspiration. While bilateral diaphragmatic paralysis causes severe shortness of breath, hemidiaphragm paralysis (HDP) gives fewer symptoms at rest, making it difficult to recognize and diagnose. Because this condition is rare, little is known regarding its consequences on breathing efficiency. Hypothesis: Based on previous studies, we hypothesized that body positions substantially affect the efficiency of breathing in a patient with unilateral hemidiaphragm paralysis and the corresponding physiological parameters. Aims: To measure and compare the amplitudes of abdominal and chest movements in different body positions in an individual with HDP and measure parameters indicating breathing efficiency. Patient and Methods: The patient had HDP due to iatrogenic phrenic nerve injury. Changes in the circumference of the abdomen and chest were measured during inhalation and exhalation with respiratory plethysmography belts (placed on standardized reproducible positions on the chest and abdomen) in different body positions: sitting (SI), standing (ST), lying (SU) and prone (PR). Breathing frequency was calculated, and blood oxygen saturation (SpO2) was measured with a pulse oximeter. Results: The percentage (%) contributions of abdominal breathing were SI: 16.0; ST: 50.3; SU: −53.5; PR: 1.1. A negative sign shows paradoxical breathing. Blood oxygen saturation (SpO2) in the four positions was SI: 93%; ST: 93%; SU: 82%; and PR: 82%, whereas the respiratory rate (1/min) was SI:19.4; ST: 15.0; SU: 37.5; PR: 35.9. Conclusions: Body position markedly influences the relative contributions of abdominal and thoracic breathing and overall respiratory efficiency in patients with hemidiaphragm paralysis; abdominal breathing in the supine and prone positions is greatly reduced leading to decreased blood oxygen saturation, a compensatory increase in respiratory rate, and severe dyspnea even at rest.