Pleural bupivacaine placement for optimal postthoracotomy pulmonary function: a prospective, randomized study.

OBJECTIVE

To determine dependent chest tube losses of bupivacaine with paravertebral versus interpleural administration, thereby helping to explain the significant differences in pulmonary function that exist between these two techniques.

DESIGN

A prospective, randomized study.

SETTING

A single hospital.

PARTICIPANTS

Twelve adult patients undergoing posterolateral thoracotomies.

INTERVENTIONS

Paravertebral or interpleural administration of bupivacaine.

MEASUREMENTS AND MAIN RESULTS

Analgesia, as assessed by visual analog pain scores and patient-controlled morphine requirements, was similar in both groups. Postoperative spirometric values were significantly better at most times with the paravertebral route of administration. Dependent chest tube bupivacaine losses were approximately four times higher in the interpleural group.

CONCLUSION

Local anesthetic on the diaphragm might actively impair respiratory function through diaphragmatic and abdominal muscle weakness, while failing to contribute to pain relief.