Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2002
Preoperative factors associated with postoperative change in confusion assessment method score in hip fracture patients.
Postoperative delirium is a major problem in elderly patients undergoing surgical repair of hip fracture. It is imperative to identify potentially treatable preoperative factors associated with the onset of postoperative delirium to optimize outcome. We sought to determine what preoperative variables are associated with postoperative delirium in geriatric patients undergoing surgical repair of hip fracture. In a prospective, IRB-approved study, patients admitted to the geriatric hip fracture service were examined daily in the hospital for the occurrence of postoperative delirium. All patients with a preoperative diagnosis of dementia or delirium were eliminated. A positive confusion assessment method score ([+]CAM) was used to determine the presence of postoperative delirium during the acute hospital stay. To determine the association between preoperative variables (demographics, laboratory values, and comorbidities) and postoperative (+)CAM scores, chi(2) and logistic regression analysis were performed with calculation for the odds ratios (OR). One-hundred-sixty-eight patients (72% women) were included in the analysis. Twenty-eight percent (n = 47) of patients had a (+)CAM score. Three variables were significant predictors of a (+)CAM score: (a) normal white blood cell count (OR, 2.2), (b) abnormal serum sodium (OR, 2.4); and (c) ASA physical status >II (OR, 11.3). The results suggest that preoperative medical conditions (abnormal serum sodium and ASA physical status >II) and an inability to mount a stress response (normal white blood cell count) may influence the patient's postoperative mental status. In particular, two of the risk factors we identified may be amenable to therapy and are abnormal serum sodium and lack of an increase in white blood cell count during the stress of trauma and surgery. ⋯ This prospective study investigated preoperative variables that are predictive of postoperative delirium in geriatric patients undergoing surgical repair of hip fracture. The results suggest that the patient's preoperative medical condition and inability to mount a stress response influence postoperative delirium.
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Anesthesia and analgesia · Jun 2002
Central neuraxial blockade promotes external cephalic version success after a failed attempt.
External cephalic version (ECV) has been successfully used to decrease the fetal and maternal morbidity and costs of cesarean delivery. As there are limited data regarding the use of central neuraxial blockade in the setting of previously failed ECV attempts, we sought to evaluate the efficacy and safety of spinal and epidural anesthesia in this setting. A retrospective review of all ECV attempts performed by a single experienced obstetrician between 1995 and 1999 was conducted. Standardized tocolytic and anesthetic regimens were used. A total of 77 patients underwent ECV attempts; of these, 37 (48%) were unsuccessful, 15 of which consented to further attempts with anesthesia. Neuraxial anesthesia was associated with frequent ECV success in both multiparous 4/4 (100%) and nulliparous 9/11 (82%) parturients. Overall 5/6 (83%) and 8/9 (89%) (P = NS) ECV attempts were successful with spinal and epidural anesthesia, respectively, with 2/5 (40%) and 6/8 (75%) (P = NS) resulting in vaginal deliveries. One successful ECV in the epidural group had an urgent cesarean delivery for persistent fetal bradycardia with good neonatal and maternal outcomes. We conclude central neuraxial anesthesia promotes successful ECV after previously failed ECV attempts. ⋯ Our retrospective analysis of central neuraxial techniques, both epidural and spinal anesthesia, noted a significant success rate in the setting of previously failed external cephalic version attempts.
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Anesthesia and analgesia · Jun 2002
Case ReportsAn unusual presentation of end-tidal carbon dioxide after esophageal intubation.
This article discusses the inherent danger of general anesthesia and the need for a variety of tools to safely manage the airway.
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Anesthesia and analgesia · Jun 2002
Pressure support compared with controlled mechanical ventilation in experimental lung injury.
It has been suggested that, in acute lung injury (ALI), spontaneous breathing activity may increase oxygenation because of an improvement of ventilation-perfusion distribution. Pressure support ventilation (PSV) is one of the assisted spontaneous breathing modes often used in critical care medicine. We sought to determine the prolonged effects of PSV on gas exchange in experimental ALI. We hypothesized that PSV may increase oxygenation because of an improvement in ventilation-perfusion distribution. Thus, ALI was induced in 20 pigs by using repetitive lung lavage. Thereafter, the animals were randomized to receive either PSV with a pressure level set to achieve a tidal volume >4 mL/kg and a respiratory rate <40 min(-1) (n = 10) or controlled mechanical ventilation (CMV) with a tidal volume of 10 mL/kg and a respiratory rate of 20 min(-1) (n = 10). Positive end-expiratory pressure was set at 10 cm H(2)O in both groups. Blood gas analyses and determination of ventilation-perfusion (.V(A)/.Q) distribution were performed at the onset of ALI and after 2, 4, 8, and 12 h. The main result was an improvement of oxygenation because of a decrease of pulmonary shunt and an increase of areas with normal .V(A)/.Q ratios during PSV (P < 0.005). However, during CMV, a more pronounced reduction of shunt was observed compared with PSV (P < 0.005). We conclude that, in this model of ALI, PSV improves gas exchange because of a reduction of .V(A)/.Q inequality. However, improvements in .V(A)/.Q distribution may be more effective with CMV than with PSV. ⋯ Assisted spontaneous breathing may have beneficial effects on gas exchange in acute lung injury. We tested this hypothesis for pressure support ventilation in an animal model of acute lung injury. Our results demonstrate that pressure support does not necessarily provide better gas exchange than controlled mechanical ventilation.
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Anesthesia and analgesia · Jun 2002
Ventilation with negative airway pressure induces a cytokine response in isolated mouse lung.
We tested the hypothesis that, under relatively low tidal volume (VT) mechanical ventilation, continuing lung decruitment induced by negative end-expiratory pressure (NEEP) would increase the lung cytokine response, potentially contributing to lung injury. Mouse lungs were excised and randomly assigned to one of 3 different ventilatory strategies: 1) the zero end-expiratory pressure group served as a control, 2) the NEEP7 group received a NEEP of -7.5 cm H(2)O, and 3) the NEEP15 group received a NEEP of -15 cm H(2)O. In all 3 groups, a VT of 7 mL/kg was used. After 2 h of ventilation, lung lavage fluid was collected for measurements of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and lactate dehydrogenase. Increases in plateau pressure before and after mechanical ventilation were significantly greater in the NEEP15 group compared with the zero end-expiratory pressure group or NEEP7 group. Lung compliance was decreased in the NEEP15 compared with the other two groups. Concentrations of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and lactate dehydrogenase in lung lavage were larger in the NEEP15 group than in the other groups. Atelectatic lung during repeated collapse and reopening of lung units accentuates the lung cytokine response that may contribute to lung injury even during relatively low VT mechanical ventilation. ⋯ Repeated closing and reopening of lung units induced by negative end-expiratory pressure resulted in lung inflammation and cell injury even under mechanical ventilation using a normal tidal volume. This finding may have clinical relevance in certain patients who are prone to atelectasis during mechanical ventilation.