Journal of clinical monitoring
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In 38 adults undergoing cardiac surgery, 4 indirect blood pressure techniques were compared with brachial arterial blood pressure at predetermined intervals before and after cardiopulmonary bypass. Indirect blood pressure measurement techniques included automated oscillometry, manual auscultation, visual onset of oscillation (flicker) and return-to-flow methods. Hemodynamic measurements or calculations included heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. ⋯ The mean measurement errors (arterial minus indirect values) for the individual indirect blood pressure methods were, for systolic: 0 mm Hg for oscillometry, 9 mm Hg for auscultation, -5 mm Hg for flicker, 7 mm Hg for return-to-flow; for mean: -6 mm Hg for oscillometry, and -3 mm Hg for auscultation; and for diastolic: -9 mm Hg for oscillometry and -8 mm Hg for auscultation. Mean measurement error for systolic blood pressure was thus least with automated oscillometry and greatest with manual auscultation, while standard deviations ranging from 9 to 15 mm Hg confirmed the highly variable nature of single indirect blood pressure measurements. Except for oscillometric diastolic blood pressure, a combination of systemic hemodynamics (heart rate, stroke volume index, systemic vascular resistance index, and cardiac index) correlated with each indirect blood pressure measurement error, which suggests that particular numeric ranges of these variables minimize measurement error.(ABSTRACT TRUNCATED AT 400 WORDS)
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The esophageal stethoscope is used often during anesthesia to monitor ventilation and cardiac function. Deficiencies in observer vigilance may limit the effectiveness of this monitoring instrument. The aim of this study was to determine how long it took for an observer to detect a surreptitiously occluded monaural esophageal stethoscope in the setting of clinical anesthesia. ⋯ However, 13% of detections were delayed for more than 60 seconds, and 2.3% for more than 240 seconds. While anesthesia personnel using an esophageal stethoscope could detect most stethoscope occlusions, failure to appreciate such episodes occurred in a small but significant number of cases. This suggests that the esophageal stethoscope has some definite limitations as a continuous monitor and that other monitoring techniques, such as oximetry, capnography, and ventilator disconnect alarms, as well as visual/tactile inspection of the patient, should be used as well.
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The proponents of automated anesthetic records list the ostensibly logical reasons for them and then claim that automated records will make everything better. The logic goes as follows: (1) It is good to have accurate records because accurate records (a) make clinical decision making more effective and improve patient safety, (b) provide better defense against frivolous lawsuits, and (c) enable more astute medical policy decisions based on improved retrospective case reviews; (2) automatic record-keeping systems will give more nearly accurate records; (3) therefore, quality of care will improve if we acquire automatic record-keeping systems. ⋯ Having said all this, however, I do believe that automated record systems will be implemented and they will be extremely useful, both for the patient and for those who care for the patient. However, we must exercise great care in their design and implementation, lest they wind up doing more harm than good.
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Multicenter Study Comparative Study Clinical Trial
Transcutaneous PCO2 and PO2: a multicenter study of accuracy.
A multicenter study used 756 samples from 251 patients in 12 institutions to compare arterial (PaO2, PaCO2) with transcutaneous (PsO2, PsCO2) oxygen and carbon dioxide tensions, measured usually at 44 degrees C. Of these samples, 336 were obtained from 116 neonates, 27 from 25 children with cystic fibrosis, and 140 from 40 patients under general anesthesia. Ninety-one patients were between 4 weeks and 18 years of age, 32 were between 18 and 60 years, and 12 were over 60. ⋯ Bias was + 0.2 +/- 2.7 mm Hg when PaCO2 was less than 30 mm Hg (N = 175, NS), 1.0 +/- 3.4 with 30 less than PaCO2 less than 40 (n = 329, p less than 0.001), and + 2.04 +/- 4.00 mm Hg with 40 less than PaCO2 less than 70 (n = 229, p less than 0.001). These data suggest that, using transcutaneous PCO2 monitors with inbuilt temperature correction of 4.5%/degrees C, the skin metabolic offset should be set to 6 mm Hg. The linear regression was PsCO2 = 1.052(PaCO2) - 0.56, Sy.x = 3.92, R = 0.929 (n = 756); and PsCO2 = 1.09(PaCO2) - 1.57, Sy.x = 4.17, R = 0.928 in neonates (n = 336).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Self-tuning adaptive control of induced hypotension in humans: a comparison of isoflurane and sodium nitroprusside.
Induced hypotension is commonly used during surgery to decrease arterial pressure. Sodium nitroprusside and isoflurane are well-known hypotensive agents. The use of self-tuning adaptive control of induced hypotension was assessed with the use of sodium nitroprusside and isoflurane as hypotensive agents. ⋯ This group of patients was compared with 10 similar patients in whom infusions of sodium nitroprusside were controlled manually by an anesthesiologist. Although the results of the two studies varied, no conclusion could be drawn regarding the superiority of either manual or closed-loop control. When manual versus automatic control of isoflurane-induced hypotension was assessed in a similar fashion, the two methods of induction were found to be comparable.