Effect of lung volume reduction surgery for emphysema on diaphragm function

• Preoperative prediction of a successful outcome following lung volume reduction surgery (LVRS) for emphysema is imperfect. One mechanism could be improvement in respiratory muscle function yet controversy exists regarding the magnitude and mechanism of such an improvement. Therefore, we measured diaphragm strength in 18 patients before and after LVRS. Mean (S.D.) FRC fell from 6.53 to 5.40l (p=0.0001). Mean sniff transdiaphragmatic pressure increased from 76 to 87cmH(2)O (14%, p<0.03) and mean twitch transdiaphragmatic pressure (Tw Pdi) increased by 2.5cmH(2)O at 3 months (12%, p=0.03). There was a highly significant increase in twitch esophageal pressure (Tw Pes) (60%, p<0.0001), which was maintained at 12 months (46% increase, p=0.0004). No change was observed in quadriceps twitch tension in nine subjects in whom it was measured. After LVRS the ratio Tw Pes:Tw Pdi increased from 0.24 to 0.37 at 3 months (p=0.0003) and 0.36 at 12 months (p=008). Low values of Sn Pdi, Sn Pes, Tw Pes and a high RV/TLC ratio were the preoperative variables most predictive of improvement in shuttle walking distance. We conclude that LVRS improves diaphragm function primarily by alteration of lung volume. Patients with poor diaphragm function and high RV/TLC ratio preoperatively are most likely to benefit from the procedure.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Lungmedicin och allergi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Respiratory Medicine and Allergy (hsv//eng)

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