The pre-operative chest film in relation to post-operative management--some effects of different projection, posture and lung inflation.

An essential feature in the assessment of chest films is the comparability of successive examinations. This is particularly important in post-operative care and there are several factors which make the conventional departmental chest film an inappropriate standard for assessment of post-operative chest films. Pre-operative chest films in patients undergoing cardiac surgery have, therefore, been taken in both upright and supine positions at full inspiration (total lung capacity) (TLC) and at resting expiration (functional residual capacity) (FRC) and then compared with those taken post-operatively. Significant differences in transverse cardiac diameter, cardio thoracic ratio, mediastinal width and vertical lung height were found in films taken with the patient supine, AP at inspiration or resting expiration, circumstances in which many chest films are taken in both post-operative and in intensive care patients. The taking of pre-operative films at lung volumes and in postures comparable with those occurring post-operatively is advocated.