[Changes of respiratory function after lung resection--taking notice of changes during exercise test and anaerobic...

Changes in the following respiratory functions during exercise test were examined before and after surgery in 31 patients undergoing pulmonary resection: VE, VCO2, and VT at a constant VO2 during exercise; and VO2, VCO2, VE and VT at constant loading (watt). At the level of 300 and 500 ml/min of VO2, VCO2 showed no significant difference before and after the operation but when VO2 reached 700 ml/min. VCO2 showed a significant increase from 542.0 +/- 78.3 ml/min to 595.5 +/- 85.2 ml/min postoperatively (p < 0.05). When exercise load was 45 watt, VE showed no significant difference before and after the operation, but when exercise load was 60 watt, VE showed a significant increase from 30.16 +/- 5.38 L/min to 33.89 +/- 4.69 L/min postoperatively (p < 0.005). These results indicated an early acceleration of ventilation in low load postoperatively. With respect to anaerobic metabolism, AT, oxygen uptake to work rate (delta VO2/delta WR), and our proposed index calculated as an area using the cumulative oxygen uptake were compared pre- and postoperatively. The results indicated that AT decreased significantly from 716.0 +/- 190.8 ml/min to 528.4 +/- 150.7 ml/min (p < 0.001), and delta VO2/delta WR also decreased significantly from 13.5 +/- 4.0 ml/min/W to 11.3 +/- 4.2 ml/min/W (p < 0.05). The index calculated as area showed a significant increase from 4070.2 +/- 3468.8 to 5095.3 +/- 3854.5 (p < 0.05). All these findings indicated that anaerobic metabolism increases postoperatively. Accordingly we conclude that postoperative increase of anaerobic metabolism causes postoperative acceleration of ventilation in low load.