Akira Inamoto

Postoperative Pain Relief and Respiratory Function in ManComparison Between Intermittent Intravenous Injections of Meperidine and Continuous Lumbar Epidural Analgesia

The effect of postoperative pain relief on cardiopulmonary function was examined quantitatively in 36 patients who underwent upper abdominal surgery. Postoperative pain relief was obtained by intravenous meperidine or by mepivacaine epidurally. Expiratory volumes increased during analgesia, despite decreases in respiratory rate and minute volume, especially in the epidural group. The reduction of respiratory rate and minute volume did not result in respiratory acidosis. A reduction of 7 or 8 per cent in oxygen consumption was observed in both groups during analgesia without significant changes in metabolic factors. Differences between decreased &OV0422;s/&OV0422;T in the epidural group and increased &OV0422;s/&OV0422;Tin the meperidine group were statistically significant, After the establishment of analgesia, arterial oxygen tensoin increased in the epidural group and decreased in the meperidine group. The implications of these findings for the problems of postoperative pain relief are discussed.

Roentgenographic analysis of the positions of catheters in the epidural space.

The optimum site for insertion of the needle into the epidural space for epidural anesthesia is controversial because understanding of the behavior of the catheter in the space is incomplete. This paper reports the results of roentgenographic analysis of the positions of catheters inserted into the epidural spaces of 151 patients. About 50 per cent of the catheters inserted by a conventional technique curled up or doubled back on themselves. Significant differences between the lumbar and thoracic regions were observed, in both length of catheter directly inserted and distance of the catheter tip from the puncture site. In the lumbar region, the probability that the catheter tip was situated three segments beyond the intervertebral space of insertion was only about 0.5 per cent; in the thoracic region it was about 50 per cent.

The Effects of Catecholamines on Arterial Oxygen Tension and Pulmonary Shunting during the Postoperative Period in Man

Twenty patients without clinical evidence of cardiopulmonary disease were studied before and during constant infusions of norepinephrine and isoproterenol to assess the effects of these drugs upon blood-gas tensions during breathing of 100 per cent oxygen. Norepinephrine was usually associated with an increase in arterial oxygen tension and a decrease in A-aDo2 while isoproterenol was associated with a decrease in arterial oxygen tension and an increase in A-aDo2. A significant decrease in the mean venous admixture (&OV0422; S/&OV0422; T) was observed with norepinephrine, while the reverse was seen with isoproterenol. The data suggest that isoproterenol interferes with the hypoxic pulmonary pressor response, while norepinephrine enhances this compensatory response which minimizes the arterial hypoxemia resulting from regional alveolar hypoventilation.

Oxygen breathing and QS/QT during postoperative pain relief in man

RésuméL’hypoxémie post opératoire à la suite de l’anesthésie a été surtout attribuée à l’atélectasie ou aux anomalies ventilateur perfuseur au niveau du poumon. Pour distinguer les anomalies ventilateur perfuseur de l’atélectasie, nous avons donné à respirer de l’oxygène pur à des malades durant la période post-opératoire après une sédation adéquate avec de la meperidine ou une analgésie épidurale, le shunt pulmonaire a été mesuré avant et après inhalation de l’oxygène. Après abolition de la douleur avec l’une ou l’autre méthode, le shunt Qs/Qt a augmenté de façon significative lors de l’exposition à l’oxygène pur si on le compare à la respiration à l’air libre. Il n’y a pas eu de différence entre le groupe traité avec la mépéridine ou l’analgésie épidurale. D’aprèsces résultats, nous pouvons conclure que la différenciation entre les anomalies ventilateur perfuseur et l’atélectasie par la méthode de l’inhalation d’oxygène pur n’est pas possible dans tous les cas à cause de l’affaissement alvéolaire qui se développe par denitrogenation dans ces circonstances, de sorte que l’effet négatif de l’atélectasie miliaire peut être plus grand que l’effet positif de l’abolition des inégalités ventilateur perfuseur créée par l’inhalation d’oxygène pur. Nous avons aussi passé en revue les autres facteurs susceptibles d’augmenter le shunt durant l’inhalation d’oxygène pur.