Diaphragm motion and lung function prediction in patients operated for lung cancer – a pilot study on 27 patients

BACKGROUND The influence of the diaphragm motion to the accuracy of postoperative lung function prediction after the lung resction is still debatable. METHODS Prospective study that included 27 patients who underwent a lung resection for cancer. Diaphragm movements were assessed radiographically and by ultrasonography before the operation and postoperatively, with the lung fully expanded. The relationship between the diaphragm movements and differences between ppo FEV1 and measured postoperative FEV1, was analysed by expressing diaphragm movements as preoperative diaphragm amplitudes, preoperative-postoperative amplitude differences or in relation to fixed intrathoracic distances. RESULTS The mean difference between preoperative and postoperative diaphragm amplitudes of the diseased side was 2.42 ± 1.25 cm and 2.11 ± 2.04 cm when measured radiographically and by ultra sound respectively (p > 0.05). A significant positive correlation was found for the entire group only between the patients' height and the differences ppo FEV1 - actual FEV1: the prediction was more unprecise in taller patients. With the cut-off value of 550 ml for differences between ppo FEV1 and actual FEV1, a significant inverse correlation was found only if the preoperative ipsilateral diaphragm amplitude was presented as a percentage of the preoperative apex-base distance in inspiration. For right-sided tumours, the greater the difference between preoperative and postoperative ipsilateral diaphragm amplitudes, the greater discrepancy between predicted and actual postoperative FEV1. For left-sided tumours, inverse correlation existed if the preoperative diaphragm amplitude was presented as a percentage of the preoperative distance apex-base. CONCLUSION Diaphragm movements influence the accuracy of the postoperative lung function prediction.