Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1986
Plasma and cerebrospinal fluid progesterone concentrations in pregnant and nonpregnant women.
Pregnancy is associated with a wider dermatomal spread of local anesthetics after epidural and spinal anesthesia. This phenomenon also exists in the immediate postpartum period. The mechanism of this observation is unresolved. ⋯ The CSF progesterone concentrations in term parturients (3 +/- 0.28 (SEM) ng/ml) and postpartum patients (1.03 +/- 0.16 ng/ml) were eight and three times greater than that of nonpregnant women (0.39 +/- 0.01 ng/ml). Significantly less lidocaine was needed (P less than 0.05) for comparable segmental levels of spinal anesthesia in term and postpartum patients than in nonpregnant individuals. These data suggest that high CSF, plasma progesterone concentrations, or both may augment the anesthetic spread of lidocaine.
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Anesthesia and analgesia · Sep 1986
Cardiopulmonary effects of oleic acid-induced pulmonary edema and mechanical ventilation.
In order to define the mechanisms whereby cardiac output and arterial oxygen transport are reduced by acute permeability pulmonary edema and by positive end-expiratory pressure (PEEP), hemodynamic, respiratory, and lung water changes were measured in 12 mechanically ventilated dogs prior to the injection of oleic acid and at 1, 2.5, and 4 hr after the injection. Measurements were performed at each interval before and after the addition of 20 cm H2O PEEP. Positive end-expiratory pressure was not continued between measurements. ⋯ However, PEEP also significantly increased the lung water content and pulmonary vascular resistance, and decreased the RV volume and stroke volume by 33%. The extravasation of fluid from the intravascular to the interstitial and alveolar spaces of the lung with oleic acid pulmonary edema is associated with substantial decreases in right ventricular volume and stroke volume and significant increases in the pulmonary vascular resistance. Treatment with 20 cm H2O PEEP further increases the lung water content and pulmonary vascular resistance and substantially reduces the right ventricular volume and stroke volume.
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The hemodynamic and metabolic effects of deflation of pneumatic tourniquets were assessed in 15 children, seven of whom had bilateral tourniquets applied. Systemic acidosis from release of lactate and PaCO2 after tourniquet deflation did not cause adverse effects in these healthy children. Larger increases in lactate were seen with longer tourniquet inflation times (greater than 75 min) or with bilateral tourniquets. ⋯ Heart rate did not change with tourniquet deflation, whereas systolic blood pressure decreased 8-10 mm Hg with deflation. Blood pressure returned to control values within 5-10 min; no arrhythmias were seen. Recommendations to minimize the systemic metabolic effects after release of tourniquets in children under general anesthesia include the following: 1) attempt to limit tourniquet inflation times to less than 75 min; 2) use controlled ventilation prior to and after tourniquet deflation to remove the respiratory component of acidosis; 3) check blood gas tensions within 5 min of tourniquet deflation in children with long tourniquet inflation times (greater than 75 min), and where bilateral tourniquets are deflated simultaneously or within 30 min of each other.