Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2003
Clinical TrialThe prevalence of preoperative diastolic filling abnormalities in geriatric surgical patients.
Preoperative assessment of heart function has typically focused on evaluating left ventricular ejection fraction (LVEF). Recent evidence suggests that diastolic heart failure is common and may cause substantial morbidity and mortality. We designed this study to examine the prevalence and potential clinical correlates of diastolic filling abnormalities as measured by echocardiography in geriatric surgical patients. Patients >=65 yr of age undergoing coronary artery surgery without concomitant valvular surgery or those with one or more risk factors for cardiovascular disease undergoing noncardiac surgery were prospectively studied. Preoperative precordial echocardiography was performed for patients undergoing noncardiac surgery, and intraoperative transesophageal echocardiography was performed for those undergoing cardiac surgery. LVEF and diastolic filling properties including E/A ratio and deceleration time were measured. Overall, 251 patients were enrolled. The mean age was 72 +/- 7 yr. Multiple linear regression analyses showed that patients with a history of myocardial infarction P = 0.021), angina pectoris (beta = -6.09, 95% CI: -9.66, -2.52; P = 0.01), and valvular heart disease (beta = -5.05, 95% CI: -9.56, -0.55; P = 0.028) had lower LVEF than those without such conditions. Of the patients with normal LVEF, 61.5% had diastolic filling abnormalities. Diastolic filling indices including E/A ratio (beta = -1.11, 95% CI -6.02, 3.78; P = 0.65) and deceleration times (beta = -3.42, 95% CI -31.28, 24.45; P = 0.81) contributed no additional predictive value for LVEF. No clinical predictors could be identified to predict diastolic filling abnormalities. For patients undergoing noncardiac surgery, analysis of variance demonstrates that the clinical assessment of LVEF using history and physical examination data was able to grossly discriminate the different levels of LVEF as compared with echocardiography (P = 0.0004). However, under-estimation of LVEF occurred more frequently than over-estimation. Although physicians' clinical assessment of systolic ejection fraction was generally accurate, geriatric patients with normal LVEF often had isolated diastolic filling abnormalities that could not be predicted by clinical factors. These results suggest that evaluation of LV systolic function alone is not discriminatory in comprehensively characterizing LV function in geriatric surgical patients. ⋯ Although physicians' clinical assessment of systolic ejection fraction was generally accurate, geriatric patients with normal left ventricular (LV) ejection fraction often had isolated diastolic filling abnormalities that could not be predicted by clinical factors. These results suggest that evaluation of LV systolic function alone is not discriminatory in comprehensively characterizing LV function in geriatric surgical patients.
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Anesthesia and analgesia · Nov 2003
Clinical TrialThe effects of isoflurane-induced electroencephalographic burst suppression on cerebral blood flow velocity and cerebral oxygen extraction during cardiopulmonary bypass.
We investigated the effects of isoflurane-induced burst suppression, monitored with electroencephalography (EEG), on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE), and autoregulation in 16 patients undergoing cardiac surgery. The experimental procedure was performed during nonpulsatile cardiopulmonary bypass (CPB) with mild hypothermia (32 degrees C) in fentanyl-anesthestized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular vein bulb oxygen saturation, and jugular venous pressure (JVP) were continuously measured. Autoregulation was tested during changes in mean arterial blood pressure (MAP) within a range of 40-80 mm Hg, induced by sodium nitroprusside and phenylephrine before (control) and during additional isoflurane administration to an EEG burst-suppression level of 6-9/min. Isoflurane induced a 27% decrease in CBFV (P < 0.05) and a 13% decrease in COE (P < 0.05) compared with control. The slope of the positive relationship between CBFV and cerebral perfusion pressure (CPP = MAP - JVP) was steeper with isoflurane (P < 0.05) compared with control, as was the slope of the negative relationship between CPP and COE (P < 0.05). We conclude that burst-suppression doses of isoflurane decrease CBFV and impair autoregulation of cerebral blood flow during mildly hypothermic CPB. Furthermore, during isoflurane administration, blood flow was in excess relative to oxygen demand, indicating a loss of metabolic autoregulation of flow. ⋯ The effects of isoflurane on cerebral blood flow velocity (CBFV) and oxygen extraction (COE) as a function of perfusion pressure were studied. When added to fentanyl anesthesia, isoflurane induced a 27% and 13% decrease in CBFV and COE, respectively. CBFV became more pressure-dependent with isoflurane indicating an impaired autoregulation.
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Anesthesia and analgesia · Nov 2003
Case ReportsFiberoptic tracheal intubation through a laryngeal mask airway in a child with Treacher Collins syndrome.
Treacher Collins syndrome (TCS) is a rare inherited condition characterized by bilateral and symmetric abnormalities of structures within the first and second bronchial arches. The mechanism of inheritance is autosomal dominant with variable expressivity. Because of this variability in expression, some affected individuals exhibit virtually no overt clinical manifestations. ⋯ Hearing loss may be due to atresia of the auditory canals or ossicular malformation of the middle ear. Despite these many development abnormalities, TCS patients are usually of normal intelligence. We report the case of a 3 1/2-yr-old patient with TCS undergoing cleft palate repair and discuss fiberoptic intubation through a laryngeal mask airway using two endotracheal (ETT) tubes secured via an ETT connector.
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There are no data about the mechanical properties of the 20-gauge reinforced Arrow epidural catheter, which has a similar design to the 19-gauge reinforced Arrow catheter. In this study, we compared the mechanical properties of 19- and 20-gauge Arrow epidural catheters at 22 degrees C and 37 degrees C. The distal 12 cm of each catheter was suspended in an enclosed chamber maintained at either 22 degrees C or 37 degrees C. A pair of forceps was applied to each catheter 5 cm from the distal end (fixed site). Another pair of forceps was applied 15 cm from the catheter tip (traction site). The catheter was pulled. At 22 degrees C, the mean fracture force was 2.24 kg (range, 1.96 - 2.41 kg) for 5 19-gauge catheters and 2.17 kg (range, 2.04-2.41 kg) for 5 20-gauge catheters. At 37 degrees C, the mean force was 1.98 kg (range 1.84- 2.15 kg) for 5 19-gauge catheters and 1.99 kg (range, 1.81-2.09 kg) for 5 20-gauge catheters. There were no significant differences in tensile strength between the two different gauge catheters at either temperature. All the 19-gauge catheters fractured at the same "fixed site" at both temperatures. All the 20-gauge catheters elongated at the "fixed site" but fractured at the "traction site." We conclude that using the smaller-gauge catheter (20-gauge) is not associated with a more frequent rate of fracture. ⋯ The 20-gauge Arrow epidural catheters had similar tensile strengths as the 19-gauge epidural catheters but fractured at the traction site rather than at the fixed site. Thus, the 20-gauge Arrow catheter may be a reasonable alternative to the 19-gauge Arrow catheter.
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Anesthesia and analgesia · Nov 2003
Suppression of natural killer cell activity and promotion of tumor metastasis by ketamine, thiopental, and halothane, but not by propofol: mediating mechanisms and prophylactic measures.
Postoperative immunosuppression is partly ascribed to anesthesia and has been suggested to compromise patients' resistance to infection and tumor metastasis. We compared the effects of various anesthetics on natural killer (NK) cell activity and on resistance to experimental metastasis, and studied mediating mechanisms and prophylactic measures. Fischer 344 rats served as controls or were anesthetized for 1 h with ketamine, thiopental, halothane, or propofol. Anesthetized rats were either maintained in normothermia or left to spontaneously reach 33 degrees C-35 degrees C. Rats were then injected IV with MADB106 tumor cells, and 24 h later lung tumor retention was assessed, or 3 wk later, lung metastases were counted. Additionally, the number and activity of circulating NK cells were assessed after anesthesia. All anesthetics, except propofol, significantly reduced NK activity and increased MADB106 lung tumor retention or lung metastases. Hypothermia had no significant effects. Ketamine increased metastasis most potently, and this effect was markedly reduced in rats pretreated with a beta-adrenergic antagonist (nadolol) or with chronic small doses of an immunostimulator (polyriboinosinic:polyribocytidylic acid). Overall, the marked variation in the NK-suppressive effects of anesthetics seems to underlie their differential promotion of MADB106 metastasis. Prophylactic measures may include perioperative immunostimulation and the use of beta-blockers. ⋯ This study in a rat model of pulmonary metastasis demonstrates that some anesthetics, but not others, increase susceptibility to tumor metastasis, apparently by suppressing natural killer cell activity. Ketamine was most deleterious, and its effects were prevented by peripheral blockade of beta-adrenoceptors combined with low levels of immunostimulation.