Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 1999
Voiding in patients managed with or without ultrasound monitoring of bladder volume after outpatient surgery.
The goal of this study was to determine whether recovery room monitoring of bladder volume would affect patient outcome after ambulatory surgery. Incidence of urinary retention and times to void and to discharge were compared in 161 patients managed with ultrasound bladder monitoring versus 173 controls without bladder monitoring. Urinary retention was diagnosed by clinical means or by ultrasound, confirmed by bladder catheterization. Patients were required to void or were catheterized before discharge. In the control patients without underlying risk factors for retention, median time to void was 95 min, and retention occurred in 0.8%, which was not significantly different from the ultrasound group (80 min and 0%, respectively). After hernia/anal surgery or spinal/epidural anesthesia, voiding was delayed (130 and 213 min), incidence of retention was increased (17% and 13%), and there was a trend toward earlier voiding (168+/-99 vs. 138+/-68 min) with bladder monitoring. We conclude that most patients at low risk of retention void within 3 h of outpatient surgery; their outcome is unaffected by bladder monitoring. After hernia/anal surgery and spinal/ epidural anesthesia, the likelihood of urinary retention is increased, and ultrasound monitoring facilitates deciding whether such patients should be catheterized. ⋯ Incidence of bladder catheterization and urinary retention were compared in patients managed with and without ultrasound monitoring of bladder volume after outpatient surgery. Monitoring did not alter outcome in patients at low risk of retention, but it facilitated determining when to catheterize patients at high risk of retention (hernia/anal surgery, spinal/epidural anesthesia).
-
Anesthesia and analgesia · Jul 1999
The effects of sevoflurane and nitrous oxide on middle cerebral artery blood flow velocity and transient hyperemic response.
We studied the effects of sevoflurane, with and without nitrous oxide, on the indices of cerebral autoregulation (transient hyperemic response ratio and the strength of autoregulation) derived from the transient hyperemic response (THR) test. Twelve patients (ASA physical status I or II) aged 18-40 yr presenting for routine non-neurosurgical procedures were recruited. The middle cerebral artery blood flow velocity was continuously recorded using transcranial Doppler ultrasonography. Preinduction THR tests were performed before the patients were anesthetized with alfentanil, propofol, and vecuronium. End-tidal carbon dioxide concentration and mean arterial pressure (to within 10% with a phenylephrine infusion) were maintained at their preinduction values. THR tests were performed sequentially at the following end-tidal sevoflurane concentrations: 2.2% in oxygen, 3.4% in oxygen, 3.4% with 50% nitrous oxide in oxygen, and 2.2% with 50% nitrous oxide in oxygen. Neither 2.2% nor 3.4% sevoflurane significantly affected cerebral autoregulation. The addition of 50% nitrous oxide to the 2.2%, but not the 3.4%, concentration of sevoflurane increased middle cerebral artery blood flow velocity and decreased autoregulatory indices significantly. ⋯ Transient hyperemic response is preserved during sevoflurane anesthesia but is significantly impaired when nitrous oxide is added to the lower concentration of sevoflurane (2.2%). These findings have implications for neurosurgical patients undergoing general anesthesia.
-
Anesthesia and analgesia · Jul 1999
An operating room scheduling strategy to maximize the use of operating room block time: computer simulation of patient scheduling and survey of patients' preferences for surgical waiting time.
Determining the appropriate amount of block time to allocate to surgeons and selecting the days on which to schedule elective cases can maximize operating room (OR) use. We used computer simulation to model OR scheduling. Inputs in the computer model included different methods to determine when a patient will have surgery (on-line bin-packing algorithms), case durations, lengths of time patients wait for surgery (2 wk is the median longest length of time that the outpatients [n = 367] surveyed considered acceptable), hours of block time each day, and number of blocks each week. For block time to be allocated to maximize OR utilization, two parameters must be specified: the method used to decide on what day a patient will have surgery and the average length of time patients wait to have surgery. OR utilization depends greatly on, and increases as, the average length of time patients wait for surgery increases. ⋯ Operating room utilization can be maximized by allocating block time for the elective cases based on expected total hours of elective cases, scheduling patients into the first available date provided open block time is available within 4 wk, and otherwise scheduling patients in "overflow" time outside of the block time.
-
Anesthesia and analgesia · Jul 1999
The spinal antinociceptive effects of a novel competitive AMPA receptor antagonist, YM872, on thermal or formalin-induced pain in rats.
Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonists have spinally mediated analgesic effects on acute nociception; however, their current formulations are not water-soluble and have toxic side effects. A new competitive AMPA antagonist, YM872 (2,3-dioxo-7-[1H-imidazol-1-yl]-6-nitro-1,2,3,4-tetrahydro-1-quinoxal inyl acetic acid) is water-soluble and may have fewer side effects. The purpose of this study was to investigate the analgesic effects of YM872 on both acute thermal and irritant-induced pain. Sprague-Dawley rats were implanted with chronic lumbar intrathecal catheters and were tested for their tail withdrawal response by the tail flick test and for their paw flinches by formalin injection after the intrathecal administration of YM872. The tail flick latency increased dose-dependently with a 50% effective dose (ED50) value of 1.0 microg. The number of flinches in both Phase 1 and Phase 2 of the formalin test decreased with increasing dose of YM872. ED50 values were 0.24 microg in Phase 1 and 0.21 microg in Phase 2. YM872 10 and 30 microg induced motor disturbance and flaccidity. In rats, the intrathecal administration of YM872 had analgesic effects on both acute thermal and formalin-induced nociceptions. Transient motor disturbance and flaccidity occurred only with large doses. YM872 may have potential in the clinical management of both acute and chronic pain. ⋯ A novel alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor antagonist, YM872, may have an analgesic effect on both acute and chronic pain when administered intrathecally.
-
Anesthesia and analgesia · Jul 1999
Comment Letter Case ReportsPostdural puncture headaches in special patient populations.