Distribution of Local Anesthetics Injected into the Interpleural Space, Studied by Computerized Tomography

Abstract

Twenty‐one patients were given interpleural analgesia for postoperative pain relief after cholecystectomy, or renal or breast surgery. The patients were classified randomly into two groups: an interpleural injection of 20 ml of 0.375% bupivacaine mixed with 10 ml contrast medium was given to 11 patients in the supine position, and 10 in the lateral position. The patients remained in this position for 1 h. There was no significant difference in the rostrocaudal distribution of the contrast on computerized tomography taken 20 min later: Th3‐L1 in the supine group vs. Th5‐L1 in the lateral group. In the supine group the mean level of contrast medium reached significantly higher medially along the mediastinum (51 ± 11 mm) than laterally (27 ± 11 mm).

A prospective, randomized comparison of interpleural and paravertebral analgesia in thoracic surgery

“…Intermittent clamping of the dependent chest drain would be unlikely to improve analgesia or pulmonary function, and this has been confirmed clinically [11,12]. In many studies patients are kept supine for up to 20 min after a bolus to facilitate diffusion of local anaesthetic through the parietal pleura into the intercostal nerves [10][11][12][13][14][15]. We used a postoperative continuous infusion regimen, which has been recommended in the interests of efficacy [13,[15][16][17], but which would require a continuous supine posture for optimum analgesic effect.…”

“…The worse PFT values in group 2 may have resulted from impairment of respiration by pooling of bupivacaine on the diaphragm. Interpleural distribution of local anaesthetic, even with an intact negative interpleural pressure, is known to be gravity-dependent [10], but following thoracotomy which produces a postoperative size mismatch between the lung and chest cavity [6] and with elimination of subatmospheric pressure, this effect would be almost complete. As we nurse our patients in the sitting position, diaphragmatic function was probably adversely affected by this mechanism.…”

Thoracic paravertebral block

“…76 We questioned whether respiratory muscle function was being actively impaired by gravity-dependent pooling of local anaesthetic on the diaphragm as we routinely nurse our postoperative patients in the sitting position. 97 Bupivacaine after intrapleural administration is known to be avidly taken up by the diaphragm. 98 Dependent chest drain losses of local anaesthetic, which can be approximately 30% to 40% with intrapleural blocks, 25 are much less with paravertebral infusion.…”

Comparative evaluation of effects of intrapleural block with adjuvants on analgesia and pulmonary function after intercostal drainage: A pilot study

“…[19][20][21] Computerized tomographic studies using contrast media in the intra-pleural injectate demonstrated fluid spread in a gravity-dependent manner. 22 Most of the fluid collected in the most dependant part of the pleural cavity but no drug collected in the epidural or paravertebral spaces. They concluded that spread of the drug varies with body position.…”