Articles: general-anesthesia.
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Anesthesia for cesarean section should ideally provide adequate muscle relaxation, analgesia, and narcosis or sedation for optimal operating conditions and safety to the dam. Since drugs that depress the dam must cross the blood-brain barrier, however, it is impossible to anesthetize the dam and not expose the fetuses to the anesthetic. No one agent or protocol is ideal for all dams, and satisfactory anesthesia for cesarean section can be induced in a number of ways. Cesarean section can be performed with either regional or general anesthesia.
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We tested the hypothesis that different anesthetic techniques for elective cesarean section would be reflected in the pattern of breathing and its control after birth. The pattern of breathing, including tidal volume, total breath duration (TTOT), minute ventilation, inspiratory (TI) and expiratory times, TI/TTOT ratio, and mouth occlusion pressure, was measured in 27 infants delivered by elective cesarean section during maternal epidural (lidocaine-carbon dioxide-epinephrine, n = 19) or general anesthesia (66% oxygen in N2O and 0.5% halothane, n = 8) at 10, 60, and 90 min and 3-5 days of age. ⋯ In general, at any given age the values of the respiratory parameters measured and their variability were similar between the two groups of infants. These findings indicate that the pattern of breathing after birth is not different following epidural or general anesthesia, and on the basis of our measurements, both epidural or general anesthesia appeared equally suitable for elective cesarean section.
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Associations between airway closure, alveolar-arterial oxygen tension difference (A-aDO2), and positive end-expiratory pressure (PEEP) were investigated in anesthetized, paralyzed, artifically ventilated patients. The difference between closing capacity (CC) and functional residual capacity (FRC) was measured with a modified standard technique using a bolus of N2 to detect airway closure in denitrogenated patients. At FIO2 = 0.4 during anesthesia before application of PEEP, A-aDO2 was larger than expected in comparable conscious subjects and increased at about 1 mmHg/yr of age. ⋯ Patients in whom CC was initially below FRC failed to improve oxygenation with PEEP. At least half of the decrease in A-aDO2 associated with application of PEEP persisted for 20-30 min after the withdrawal of PEEP, although the withdrawal resulted in an immediate recurrence of airway closure above FRC. The authors conclude that closure of pulmonary units operates in some circumstances to contribute to pulmonary dysfunction in anesthetized patients but is neither the only nor necessarily the most important such mechanism.