Intrathoracic Pressure in Haemothorax, Pneumothorax, and Pleural Effusion, and Effects of Aspiration and of Oxygen Replacement

Effect of Thoracentesis on Arterial Oxygen Tension

“…Pleural effusions cause restrictive abnor malities in pulmonary function [1,25,36] which are proportional to the volume of pleural fluid present [25,32,36]. Thoracen tesis results in an immediate fall in intrathoracic and venous pressure [1,7], but a delay of days to weeks occurs before lung vol umes return to normal levels [1,4,12,25,36].…”

“…It was concluded that significant hypoxemia may result from thoracentesis due to aberration of ventilation-perfusion relationships. It is further suggested that oxygen therapy be routinely administered during and immediately after the procedure.Although thoracentesis is routinely per formed for diagnostic purposes and to allow for the relief of dyspnea with reexpansion of atelectatic lungs, few studies of the physio logical effects of this procedure have been reported [1,7,12,25,32,36]. These inves tigations revealed that while the immediate clinical response to aspiration was frequent ly gratifying, the accompanying measurable increase in pulmonary function by spirome try was not as significant and delayed for days and weeks.…”

The Effects of Pleural Effusion on Respiration and Circulation in Man

“…Indeed, measurements of the intrapleural pressure in such patients have been recorded by Clark (12) and by Shattuck and Welles (13) and demonstrate the loss of all or most of the normal negative pressure. Following thoracentesis, the reserve air increases markedly and the intrapleural pressure has been shown to become more negative (12,13). Decreased negativity of the intrapleural pressure, consequent to any cause, impairs the efficiency of respiration and also influences cardiovascular dynamics in a manner which will be discussed below.…”