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
Evaluation of graphic cardiovascular display in a high-fidelity simulator.
"Human error" in anesthesia can be attributed to misleading information from patient monitors or to the physician's failure to recognize a pattern. A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. We designed a graphic display to show hemodynamic variables. Twenty anesthesiologists were asked to assume care of a simulated patient. Half the participants used the graphic cardiovascular display; the other half used a Datex As/3 monitor. One scenario was a total hip replacement with a transfusion reaction to mismatched blood. The second scenario was a radical prostatectomy with 1.5 L of blood loss and myocardial ischemia. Subjects who used the graphic display detected myocardial ischemia 2 min sooner than those who did not use the display. Treatment was initiated sooner (2.5 versus 4.9 min). There were no significant differences between groups in the hip replacement scenario. Systolic blood pressure deviated less from baseline, central venous pressure was closer to its baseline, and arterial oxygen saturation was higher at the end of the case when the graphic display was used. The study lends some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnose, manage, and treat critical cardiovascular events in a simulated environment. ⋯ A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. A user-centered design process led to a novel object-oriented graphic display of hemodynamic variables containing emergent features and functional relationships. In a simulated environment, this display appeared to support clinicians' ability to diagnose, manage, and treat a critical cardiovascular event in a simulated environment. We designed a graphic display to show hemodynamic variables. The study provides some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnosis, mange, and treat critical cardiovascular events in a simulated environment.
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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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Anesthesia and analgesia · Nov 2003
Propofol decreases reperfusion-induced arrhythmias in a model of "border zone" between normal and ischemic-reperfused guinea pig myocardium.
We examined the effect of propofol on the main mechanisms involved in ischemia/reperfusion-induced arrhythmias (i.e., spontaneous arrhythmias, conduction blocks, and dispersion of repolarization) in vitro. In a double-chamber bath, guinea pig right ventricular muscle strips were subjected to 30 min of simulated ischemia followed by 30 min of reperfusion (altered zone; AZ) and to standard conditions (normal zone; NZ). Action potential (AP) parameters were recorded in the NZ and AZ. We studied the effects of Intralipid(R) and of propofol at 10(-6), 10(-5), and 2 x 10(-5) M on the occurrence of spontaneous sustained arrhythmias, conduction blocks, and the dispersion of repolarization. In NZ, Intralipid and propofol did not significantly modify the AP parameters. Propofol, but not Intralipid, lessened the ischemia-induced decrease in AP duration (APD) at 90% of repolarization (APD(90)) and attenuated the APD dispersion around the "border zone." Propofol did not modify the occurrence of ischemia-induced arrhythmias. Propofol 10(-6) M, but not Intralipid or propofol at 10(-5) and 2 x 10(-5) M, decreased the occurrence of ischemia-induced conduction blocks. Propofol decreased the occurrence of reperfusion-induced spontaneous sustained arrhythmias. We conclude that, in vitro, propofol attenuated the ischemia-induced APD(90) dispersion around the "border zone" and decreased the occurrence of spontaneous arrhythmias related to myocardial reperfusion injury. ⋯ In isolated guinea pig ventricular myocardium propofol, but not Intralipid(R), attenuated the ischemia-induced shortening of action potential and, thus, the dispersion of repolarization and decreased the occurrence of spontaneous ventricular arrhythmia related to reperfusion injury. This result may be important for propofol-based anesthesia in patients at high risk for intraoperative ischemia.
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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.