Lumbar epidural anaesthesia and sensory profiles in term pregnant patients.

Sensory profiles of lumbar epidural anaesthesia were studied in 57 patients, during active labour. The local anaesthetics used were chloroprocaine three per cent with and without epinephrine, chloroprocaine two per cent, bupivacaine 0.25 per cent and a mixture of chloroprocaine three per cent and bupivacaine 0.5 per cent. A common pattern of spread was found for all local anaesthetic solutions with the onset of the block affecting the dermatomes innervated by the thinnest nerve roots (T12L1). There was a percentage of failure to block the thickest nerve root (S1). Inguinal and suprapubic discomfort ("missing segment") occurred when S1 was not blocked. Under the conditions of this experiment, the addition of bupivacaine to chloroprocaine did not increase the duration of the blockade significantly.

Respiratory depression at birth--value of Apgar score and ventilatory measurements in its detection.

The purpose of this investigation was to determine the value of ventilatory measurements and Apgar score in the diagnosis of respiratory depression in the newborn infant. The following were the results of the determinations made in 24 neonates whose mothers had received meperidine in a total dose up to 3 mg/kg within three hours prior to delivery; Respiratory rate, 51+/-3.7/minute; tidal volume, 21.4 +/- 1.5 ml; minute ventilation, 339 +/- 24 ml/kg X minute; end tidal CO2, 40.8 +/- 1.3 mm Hg; ventilatory response to CO2, 21.8 +/- 2.7 ML/KG X minute X mm Hg PACO2. The mean Apgar score was 7.1 and 9.0 at 1 and 5 minutes, respectively. None of the determinations were indicative of respiratory depression with the exception of the slope of the CO2 response curve; it was considered to be below the normal range. No correlations existed between the CO2 response curve and any other values. It is concluded that meperidine administered to mothers in labor in the described dose will not significantly alter Apgar score, VE, VT, RR, AND PAco2 in the newborn infant. The extent of respiratory center depression could be determined only by the decreased ventilatory response to CO2.