Effects of Intercostal Nerve Blocks (Etidocaine 0.5%) on Chest Wall Mechanics in Cholecystectomized Patients

In 20 patients who had undergone cholecystectomy through a right oblique incision, an intercostal nerve block with etidocaine 0.5% was performed on the day after operation — in 10 patients on the right side only and in the other 10 bilaterally. The block was applied to the 5th-11th intercostal nerves, inclusive.
Tidal volumes, respiratory variations in the perimetry of the chest and abdomen, and intraoesophageal and intragastric pressures were recorded before and after the blockades. From analyses of the relations between the relative contributions of costal and abdominal respiration, on the one hand, and intragastric pressure variations, on the other, it was found that before the blockade the intercostal muscles contributed to respiratory movements at rest, but that this contribution decreased after the blockade - to a greater extent after bilateral than after unilateral blockade. It is assumed that this return to a more normal type of breathing at rest implies relief for the patients. The nerve block led to no significant change of the fraction of abdominal breathing. Pulmonary elastance decreased after bilateral blockade, but remained unchanged after unilateral. Changes in the functional residual capacity (FRC) were evaluated by transthoracic electrical impedance pneumography. Signs of a reduction were noted after unilateral blockade, but there appeared to be no change after bilateral blockade.
Bilateral intercostal block thus seems more satisfactory than unilateral in certain respects. The differences cannot be ascribed such importance, however, that bilateral blocks should be considered obligatory in cholecystectomized patients. Probably the most important effect - the pain relief- is achieved in these patients by a right-sided block only.