Anesthesia and analgesia
-
Anesthesia and analgesia · May 1996
Randomized Controlled Trial Clinical TrialEpidural test dose: isoproterenol is a reliable marker for intravascular injection in anesthetized adults.
Epidural test doses containing more than 15 micrograms epinephrine are reliable for the detection of intravascular injection based on the conventional systolic blood pressure (SBP) criterion (positive if > or = 15 mm Hg increase) but not on the heart rate (HR) criterion (positive if > or = 20 bpm increase) in adult patients anesthetized with isoflurane. The present study was designed to test whether isoproterenol could be used as a reliable marker. Thirty adult patients were randomly assigned to one of two groups, each of which was anesthetized with 1% end-tidal isoflurane and nitrous oxide after endotracheal intubation. ⋯ On the other hand, 12 of 15 patients in the isoproterenol group and none in the saline group exhibited SBP increases > or = 15 mm Hg, resulting in 80% sensitivity and 83% negative predictive value. In the isoproterenol group, however, transient systolic hypotension ( < 80% of the preinjection value) occurred in five patients without untoward clinical sequelae. These results indicate that, based on the peak HR response, the epidural test dose containing 3 micrograms isoproterenol is a reliable marker for intravascular injection in adult patients during isoflurane anesthesia.
-
Anesthesia and analgesia · May 1996
Randomized Controlled Trial Clinical TrialDural puncture with a 26-gauge spinal needle affects spread of epidural anesthesia.
Combined spinal and epidural anesthesia may increase the risk of epidurally administered drugs spreading into the subarachnoid space through the dural hole. We studied the effect of dural puncture with a 26-gauge needle on the spread of analgesia induced by epidural injection of local anesthetics. Forty patients were randomly assigned to control and dural puncture groups. ⋯ Analgesia was assessed by pinprick at 5, 10, 15, and 20 min after injection and at the end of surgery. The caudal spread of analgesia was significantly greater in the dural puncture group than in the control group 15 and 20 min after injection (P < 0.01), but the cranial spread of analgesia was not different between the two groups. We conclude that dural puncture (without drugs) using a 26-gauge Whitacre spinal needle before epidural injection increases caudal spread of analgesia induced by epidural local anesthetics.
-
Anesthesia and analgesia · May 1996
Rapid core-to-peripheral tissue heat transfer during cutaneous cooling.
Perioperative thermal manipulations are usually directed at the skin surface because methods of directly warming the core are invasive or ineffective. However, inadequate heat flow between peripheral and core compartments will decrease the rate at which core temperature changes. We therefore determined whether core hypothermia is delayed after initiation of surface cooling. ⋯ There was no delay between initiation of active cooling and the decrease in core temperature. Furthermore, peripheral (arm and leg) and core (trunk and head) tissue heat contents decreased at virtually the same rates: approximately 50 kcal/h and approximately 47 kcal/h, respectively. These data indicate that there is little restriction of heat flow between peripheral and core tissues in vasodilated, anesthetized subjects.
-
Anesthesia and analgesia · May 1996
Comparative StudyJugular venous bulb oxyhemoglobin saturation during cardiac surgery: accuracy and reliability using a continuous monitor.
Previous studies have demonstrated the feasibility of continuously monitoring jugular venous oxygen saturation (SjO2) with a fiberoptic catheter during hypothermic cardiopulmonary bypass (CPB). In the present study, with patients maintained at either moderate (28 degrees C) or mild (32-34 degrees C) hypothermia during CPB, SjO2 values obtained from a fiberoptic catheter were compared to intermittent samples analyzed by a co-oximeter. Twenty patients scheduled for elective coronary artery or valvular surgery had a 5.5 Fr Opticath catheter inserted into the left internal jugular bulb after induction of general anesthesia. ⋯ Catheter and co-oximetry SjO2 values obtained at four time points--1) pre-CPB, 2) target CPB temperature, 3) mid-rewarming, and 4) post-CPB--were compared using linear regression, Bland-Altman analysis, and Shrout-Fleiss interclass correlation coefficient analysis. These statistical methods revealed poor correlation between the catheter and co-oximetry SjO2 values: r = 0.44 by linear regression and 0.32 by interclass correlation coefficient analysis, and was unacceptably discrepant by Bland-Altman analysis. Oxyhemoglobin saturation values obtained continuously from a jugular venous bulb fiberoptic catheter during CPB may not accurately reflect true oxyhemoglobin saturation, and caution is warranted when interpreting SjO2 values obtained from a fiberoptic catheter during CPB.
-
Anesthesia and analgesia · May 1996
Comparative StudySpectral analysis of arterial pressure variability during induction of propofol anesthesia.
We studied the effect of continuous infusion of propofol on spectral components in systemic arterial pressure (SAP) signals in 35 consenting patients undergoing abdominal surgery. Anesthesia was induced with intravenous bolus administration of propofol (2.0 mg/kg), followed by infusion at either 5 mg.kg-1.h-1 (Group 1, n = 18) or 10 mg.kg-1.h-1 (Group 2, n = 17). Tracheal intubation was facilitated by administration of vecuronium (0.1 mg/kg). ⋯ There were 14.1-, 2.8-, and 2.8-fold increases in the respective components of the SAP signal in Group 2. At all intervals, the spectral components of SAP, however, did not correlate well with the plasma concentration of propofol in either group. These results suggest that spectral analysis of SAP signals may provide an alternative for assessing autonomic activities, such as the sympathetic response, to tracheal intubation during propofol anesthesia.