Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialRapid water and slow sodium excretion of acetated Ringer's solution dehydrates cells.
Acetated Ringer's solution is a slightly hypotonic infusion fluid (osmolality 270 mosmol/kg) that has inspired the belief that the fluid causes a shift of water volume to the intracellular space. We assessed the role of the kidney in modifying this volume shift by infusing 25 mL/kg of Ringer's acetate solution (mean, 1565 mL) over a time period of 15, 30, 45, and 80 min on different occasions in 5 healthy female volunteers. Regardless of the rate of administration, the excreted urine contained only half as much sodium (mean, 67 mmol/L) as the infused fluid. As there was only a slight increase of 0.9 mmol/L in the serum sodium level, mass balance calculations indicated that 274 mL of water had shifted from the intracellular to the extracellular space 30 min after the infusions ended (P < 0.001). This fluid shift was also maintained over the subsequent 90 min. In conclusion, infusion of Ringer's acetate solution does not promote cellular swelling as a result of the excretion of urine that is low in sodium. A slight dehydration of fluid from the intracellular space still persisted when our measurements ended 2 h after completing the infusion. ⋯ The kidney promotes slight cellular dehydration after infusion of Ringer's acetate solution by rapid excretion of water, whereas natriuresis occurs more slowly. In volunteers, this translocation amounted to 18% of the infused fluid volume and persisted for at least 2 h.
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Anesthesia and analgesia · Dec 2003
Validation of an original mathematical model of CO(2) elimination and dead space ventilation.
We present an original, mathematical model of ventilation and gas-exchange. Our aim was to validate it using data from previous clinical investigations, allowing our use of it in future investigations. The first previous investigation used a low-dead space, double-lumen, tracheal tube (DLT). We matched the model's PaCO(2) and airway pressures (P(AW)) to the patient mean during use of the DLT and a single-lumen tube (SLT). The model's resulting PaCO(2), PECO(2) and P(AW) were compared with the patients' as tidal volume (VT) changed with constant minute volume. The second investigation examined dead space during anesthesia. The model's VT, respiratory rate, CO(2) production, temperature, and alveolar and anatomical dead spaces were matched to each mechanically ventilated subject. Bias and precision in predictions of PaCO(2) and PECO(2) were calculated. The model's bias in prediction of dead space reduction by the DLT was 6.9%. Bias in prediction of P(AW) was 0.1% (peak) and -5.13% (mean), of PaCO(2) was 1.2% (DLT) and 1.5% (SLT) and of PECO(2) was 1.7% (DLT) and 1.3% (SLT). Prediction of PaCO(2) and PECO(2) in the second investigation (as 95% confidence interval of bias): PaCO(2) -2.6% to 0.8% and PECO(2) -4.9% to 1.2%. This validation allows future application of our model in appropriate theoretical investigations. ⋯ We present an original, mathematical model of ventilation and gas exchange. We validate it against previously published clinical data to allow its use in future theoretical investigations where data may be unavailable from patients.
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Anesthesia and analgesia · Dec 2003
Clinical TrialThe effect of right versus left lateral decubitus positions on induction of spinal anesthesia for cesarean delivery.
Induction of spinal anesthesia for cesarean delivery in the left lateral (LL) decubitus position combined with intraoperative left uterine displacement may result in pooling of local anesthetic onto one side of the body. We studied the effect of the right lateral (RL) and LL decubitus positions during placement of spinal anesthesia on the intrathecal spread of 0.5% hyperbaric bupivacaine plus fentanyl in 60 term parturients. Though all parturients acquired a loss of cold sensation at T4 15 min after intrathecal injection, more parturients in the LL group than in the RL group did so at 5 min (P < 0.05). The maximum levels of sensory blockades, amounts of fluid, vasopressor, and supplementary analgesia used, and the incidence of postoperative complications were similar. We conclude that the two positions can be used equally well when hyperbaric bupivacaine and fentanyl are used in cesarean delivery under spinal anesthesia. ⋯ We conducted a double-blinded randomized trial comparing the spread of spinal anesthesia placed with a parturient in either the right or left lateral position. There was a faster onset in the left lateral group; however, the maximum block heights and the time taken to achieve them were similar in both groups.
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Anesthesia and analgesia · Dec 2003
The dose-related effects of ketamine on mortality and cytokine responses to endotoxin-induced shock in rats.
In our previous study, ketamine administration was found to inhibit hypotension, metabolic acidosis, and cytokine responses in endotoxemia. However, only a few studies have indicated whether ketamine has the dose-related beneficial effects after endotoxin injection. Our objective was to clarify the dose-related effects of ketamine on mortality and cytokine responses to endotoxemia in rats. ⋯ Ketamine administration thus clearly had a beneficial effect on mortality rates, with that for group M lower than for groups L and H (P < 0.05). The cytokine responses to endotoxin were somewhat suppressed in group M but not in group L. Ketamine administration dose-independently inhibited hypotension, metabolic acidosis, and cytokine responses in rats injected with endotoxin.
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Anesthesia and analgesia · Dec 2003
Case ReportsThe use of the LMA-ProSeal in airway resuscitation.
Insufflation of the stomach with air can be a complication of face mask ventilation in the case of airway obstruction. Although the laryngeal mask airway has proven value in airway resuscitation, it has two major failings: a relatively low seal pressure and lack of access to the alimentary tract. ⋯ The patient was resuscitated with a LMA-ProSeal, which permitted ventilation with high airway pressures. Return of oxyhemoglobin saturation occurred after decompression of the stomach with a gastric tube inserted via the LMA-ProSeal's gastric drain.