Anesthesia and analgesia
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Anesthesia and analgesia · May 2002
Mitral Doppler indices are superior to two-dimensional echocardiographic and hemodynamic variables in predicting responsiveness of cardiac output to a rapid intravenous infusion of colloid.
We hypothesized that mitral flow (MF) Doppler measurements could be used to predict cardiac output (CO) responsiveness to fluid challenge. Fourteen patients with normal systolic and diastolic function, scheduled for coronary artery bypass graft surgery, were evaluated as part of a pilot study in which preload was varied immediately before the beginning of cardiopulmonary bypass. A Validation group of 36 patients with different levels of systolic and diastolic function received a rapid infusion of 500 mL of 10% pentastarch. By use of transesophageal echocardiography, we measured left ventricular end-diastolic area, pulsed Doppler indices of the MF and pulmonary venous flow, and standard hemodynamic variables during acute volemic variations. A baseline measurement was first recorded, followed by measurements taken after a decrease (211 +/- 87 mL) and then an increase (176 +/- 149 mL) in preload (pilot study) and before and after 500 mL of pentastarch (validation study). In the pilot study, we found that a low velocity/time integral (VTI) E wave/A wave (E/A) ratio was associated with a larger increase in CO secondary to an increase in preload (r = 0.64, P < 0.05). Stepwise linear regression identified Doppler measurements of the mitral VTI E/A ratio as the most important variable to predict the increase in CO after fluid infusion. In the validation study, a mitral E/A ratio <1.26 before fluid infusion best predicted a 20% increase in stroke volume (receiver operating characteristic curve, 71%; P < 0.05), whereas no other hemodynamic or echocardiographic variable predicted preload responsiveness. We conclude that the MF Doppler filling pattern is an important factor to predict the increase in CO after intravascular fluid challenge in patients undergoing coronary artery bypass grafting. ⋯ In the presence of low cardiac output, the clinician's ability to identify which patients are more likely to benefit from volume administration to improve hemodynamic status while avoiding fluid overload is important. The analysis of Doppler measurement of the mitral flow as an indirect indicator of the individual diastolic pressure/volume relationship may be useful to predict the intravascular volume responsiveness in patients undergoing coronary artery bypass graft surgery.
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Anesthesia and analgesia · May 2002
Pulmonary gas exchange in coronary artery surgery patients during sevoflurane and isoflurane anesthesia.
As the surgical population ages, the number of patients presenting with coronary artery disease and age-related loss of pulmonary recoil will increase. Although their influence on gas exchange in this population remains unknown, sevoflurane and isoflurane are used for an increasing variety of surgical procedures. We examined pulmonary gas exchange (multiple inert gas elimination technique) in 30 patients presenting for coronary artery bypass grafting. After a baseline measurement taken during midazolam anesthesia, patients were continued on sevoflurane (n = 10), isoflurane (n = 10), or midazolam (n = 10) for 20 min, then a second measurement was taken. During sevoflurane and isoflurane anesthesia, blood flow to lung areas with a low ventilation/perfusion ratio (Va/Q) was significantly increased in comparison with control. During sevoflurane anesthesia, blood flow to lung areas with a normal Va/Q ratio (76 +/- 12 versus control: 89 +/- 5, mean +/- SD) and PaO(2) (138 +/- 31 versus control: 156 +/- 35 mm Hg, mean +/- SD) were depressed, whereas an increase in Va/Q-dispersion (log SD(Q)) was observed during isoflurane anesthesia. We conclude that both sevoflurane and isoflurane alter the distribution of perfusion in the lung, but only sevoflurane significantly depresses PaO(2). ⋯ Both sevoflurane and isoflurane modified pulmonary blood flow in patients with coronary artery disease, but only sevoflurane depresses arterial oxygenation in this population.
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Anesthesia and analgesia · May 2002
The effect of the combined administration of colloids and lactated Ringer's solution on the coagulation system: an in vitro study using thrombelastograph coagulation analysis (ROTEG.
Gelatin solutions are often given in clinical practice once the maximal dose of a median-weight hydroxyethyl starch (HES) has been reached. Colloids are usually combined with lactated Ringer's solution (RL). Whether the combined administration of colloids and/or crystalloids affects blood coagulation is not known. We diluted blood by 20%, 40%, and 60% with RL, gelatin (Gelofusin), 6% HES 130/0.4 (Voluven), and 6% HES 200/0.5 (Iso-Hes), as well as with combinations of these solutions at a ratio of 1:1 (gelatin/RL, 6% HES 130/0.4:RL, 6% HES 200/0.5:RL, 6% HES 130/0.4:gelatin, 6% HES 200/0.5:gelatin). Thereafter, blood was analyzed by using modified thrombelastograph coagulation analysis (ROTEG) and clotting time, clot formation time, and maximal clot firmness were determined. RL had the least effect on hemostasis. Gelatin administered alone impaired the coagulation system significantly less than each median-weight HES administered alone. We conclude that gelatin combined with 6% HES 200/0.5 or 6% HES 130/0.4 decreases hemostasis <6% HES 200/0.5 or 6% HES 130/0.4 administered alone. ⋯ The effect of the combined administration of different colloids and/or crystalloids on coagulation is not known. We show that hemostasis is less impaired using a combination of gelatin and median-weight starches than using median-weight starches alone. Furthermore, the combination of lactated Ringer's solution and gelatin decreases the coagulation system to the same extent as the combination of lactated Ringer's solution and 6% hydroxyethyl starch 130/0.4.
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Anesthesia and analgesia · May 2002
The effects of age on neural blockade and hemodynamic changes after epidural anesthesia with ropivacaine.
We studied the influence of age on the neural blockade and hemodynamic changes after the epidural administration of ropivacaine 1.0% in patients undergoing orthopedic, urological, gynecological, or lower abdominal surgery. Fifty-four patients were enrolled in one of three age groups (Group 1: 18-40 yr; Group 2: 41-60 yr; Group 3: > or=61 yr). After a test dose of 3 mL of prilocaine 1.0% with epinephrine 5 microg/mL, 15 mL of ropivacaine 1.0% was administered epidurally. The level of analgesia and degree of motor blockade were assessed, and hemodynamic variables were recorded at standardized intervals. The upper level of analgesia differed among all groups (medians: Group 1: T8; Group 2: T6; Group 3: T4). Motor blockade was more intense in the oldest compared with the youngest age group. The incidence of bradycardia and hypotension and the maximal decrease in mean arterial blood pressure during the first hour after the epidural injection (median of Group 1: 11 mm Hg; Group 2: 16 mm Hg; Group 3: 29 mm Hg) were more frequent in the oldest age group. We conclude that age influences the clinical profile of ropivacaine 1.0%. The hemodynamic effects in older patients may be caused by the high thoracic spread of analgesia, although a diminished hemodynamic homeostasis may contribute. ⋯ Analgesia levels after the epidural administration of 15 mL of ropivacaine 1.0% increase with increasing age. This is associated with an increased incidence of hypotension in the elderly, although an effect of age on the hemodynamic homeostasis may have contributed. It appears that epidural doses should be adjusted for elderly patients.
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Anesthesia and analgesia · May 2002
Case ReportsMassive hemorrhage during radiofrequency ablation of a pulmonary neoplasm.
Radiofrequency ablation is a new investigational therapy for primary and secondary neoplasms. In this article, the authors describe the anesthetic management of the radiofrequency ablation of a pulmonary neoplasm complicated by massive hemorrhage.