Edward G. Pavlin

Voiding in patients managed with or without ultrasound monitoring of bladder volume after outpatient surgery

UNLABELLED 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. IMPLICATIONS 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).

Effect of meperidine on oxygen consumption, carbon dioxide production, and respiratory gas exchange in postanesthesia shivering.

Meperidine has been used to suppress postanesthesia shivering. However, its efficacy to date has only been assessed by observation of visible shivering. We measured the effect of meperidine on oxygen consumption (&OV0312;O2), carbon dioxide production (&OV0312;CO2) and pulmonary gas exchange in 14 otherwise healthy patients shivering after general anesthesia. Meperidine successfully suppressed visible shivering in all patients and was associated with significant decreases in &OV0312;o1 and &OV0312;O2 and minute ventilation (&OV0312; E) but not with return to basal levels. Arterial PCo2 levels remained unchanged at normal, whereas significant improvements occurred in pH and bicarbonate levels. Meperidine is an effective method of reducing the elevated metabolic demand of shivering.

Management of bladder function after outpatient surgery.

BACKGROUND This study was designed to test a treatment algorithm for management of bladder function after outpatient general or local anesthesia. METHODS Three hundred twenty-four outpatients, stratified into risk categories for urinary retention, were studied. Patients in category 1 were low-risk patients (n = 227) having non-pelvic surgery and randomly assigned to receive 10 ml/kg or 2 ml/kg of intravenous fluid intraoperatively. They were discharged when otherwise ready, without being required to void. Patients in category 2 (n = 40), also presumed to be low risk, had gynecologic surgery. High-risk patients included 31 patients having hernia or anal surgery (category 3), and 31 patients with a history of retention (category 4). Bladder volumes were monitored by ultrasound in those in categories 2-4, and patients were required to void (or be catheterized) before discharge. The incidence of retention and urinary tract symptoms after surgery were determined for all categories. RESULT Urinary retention affected 0.5% of category 1 patients and none of category 2 patients. Median time to void after discharge was 75 min (interquartile range 120) in category 1 patients (n = 27) discharged without voiding. Fluids administered did not alter incidence of retention or time to void. Retention occurred in 5% of high-risk patients before discharge and recurred in 25% after discharge. CONCLUSION In reliable patients at low risk for retention, voiding before discharge appears unnecessary. In high-risk patients, continued observation until the bladder is emptied is indicated to avoid prolonged overdistention of the bladder.

Effect of Thermal Injury on the Pharmacokinetics and Pharmacodynamics of Atracurium in Humans

Thermal injury causes resistance to many nondepolarizing muscle relaxants including d-tubocurarine, metocurine, pancuronium, and atracurium. To evaluate the role of pharmacokinetics and pharmacodynamics in this phenomenon, the disposition and effect of atracurium (0.5 mg/kg iv) were studied in thermally injured patients (5 males, 16-43 yr) in comparison with that in nonburned control patients (3 males, 1 female, 24-53 yr). The decline of plasma atracurium concentration with time was biexponential in both groups of patients. There were no significant differences in the mean value of any pharmacokinetic parameter (clearance, V1, V beta, alpha and beta half-lives). The time course of effect was also similar, although the maximum twitch depression was significantly smaller (66.1% vs. 100% maximal twitch depression) and time to recover to 50% of maximal twitch depression was significantly shorter (14.2 vs. 52 min) in thermally injured patients. Patients with thermal injury had an EC50 (plasma concentration of atracurium required for 50% of the maximum possible response) 3.4 times that of control patients. Plasma-free fraction of atracurium in the thermally injured patients was 75% that in controls, and free EC50 (the product of free fraction and EC50) of the thermally injured group was 2.7 times that of controls. The results of this study confirm a pharmacodynamic mechanism for the majority of resistance to atracurium, with a diminished free fraction in plasma also contributing to this effect.

Hemodynamic Effects of External Cardiac Massage in Trauma Shock

The effectiveness of closed chest cardiopulmonary resuscitation (CCCPR) in maintaining cardiac output has been well studied in cardiac arrest. Trauma surgeons most often encounter shock secondary to hypovolemia or cardiac tamponade, and the effectiveness of CCCPR in that setting has not been established. To determine the hemodynamic effects of external massage in profound shock, hypotension was induced in baboons. Pressures obtained with external massage were compared to spontaneous intra-arterial pressures before compression. Although external massage increased systolic pressures in both tamponade and hypovolemia, diastolic pressures were consistently decreased. We conclude that CCCPR does not augment arterial pressure in the clinical situations associated with decreased LVEDV and is unlikely to provide organ perfusion for trauma victims.

Preincisional Treatment to Prevent Pain After Ambulatory Hernia Surgery

We designed this study as a randomized comparison of postoperative pain after inguinal hernia repair in patients treated with triple preincisional analgesic therapy versus standard care. Triple therapy consisted of a nonsteroidal antiinflammatory, a local anesthetic field block, and an N-methyl-d-aspartate inhibitor before incision. The treatment group (n = 17) received rofecoxib, 50 mg PO, a field block with 0.25% bupivacaine/0.5% lidocaine, and ketamine 0.2 mg/kg IV before incision; controls (n = 17) received a placebo PO before surgery. The anesthetic protocol was standardized. Postoperative pain was treated by fentanyl IV and oxycodone 5 mg/acetaminophen 325 mg PO as required for pain. Pain scores (0–10) and analgesic were recorded for the first 7 days after surgery. Pain scores were 47% lower in the treatment group before discharge (3.1 ± 0.6 versus 5.9 ± 0.6, P = 0.0026) (mean ± se) and 18% less in the first 24 h after discharge (5.6 ± 0.4 versus 6.8 ± 0.5, P = 0.05); oral analgesic use was 34% less in the treatment group (4.6 ± 0.8 doses versus 7.1 ± 0.7 doses, P = 0.02) in the first 24 h after surgery. We conclude that triple preincisional therapy diminishes pain and analgesic use after outpatient hernia repair, and encourage further evaluation of this technique.

Topical Growth Factors and Wound Contraction in the Rat: Part I. Literature Review and Definition of the Rat Model

The isolation and production of growth factors and the observation that a platelet extract will promote wound healing in chronic wounds has led to an interest in the study of growth factors and wound healing. We wished to study the effect of platelet-derived growth factor on wound contraction. However, because studies of growth factors and wound contraction are quite recent, we could find only two models described in the literature and neither seemed ideal. Both used small wounds, which are difficult to measure, anesthetics with slow induction and recovery and which are difficult to titrate, and no dressings, which permits the animals to lick the wounds and possibly introduce other growth factors. We therefore reviewed wound contraction models used for other studies. In particular, we reviewed the animal used, anesthetic, wound size and shape, dressing methods, scab treatment, and measurement and comparison techniques. We then combined features of many of them into a model that solves the problems listed and permits the study of topically applied growth factors and wound contraction. The composite model to be described uses a large, circular wound on the rat, halothane anesthesia, and flexible, Tubigrip dressings.

Oxygen Delivery and Consumption during Hypothermia and Rewarming in the Dog

Changes in oxygen consumption (VO2) and oxygen delivery (DO2) were compared in three groups of paralyzed, sedated dogs: 1) a group (n = 5) cooled to 29 degrees C and immediately rewarmed to 37 degrees C; 2) a group (n = 5) cooled to and maintained at 29 degrees C for 24 h, and then rewarmed; and 3) a group (n = 5) maintained at 37 degrees C for 24 h. During the cooling phase, in both the acute and prolonged hypothermia animals, VO2 and DO2 decreased significantly from control values (P less than 0.05). The decrease in DO2 occurred as a result of a similar decrease in cardiac index (CI; P less than 0.05) that was associated with a significant increase in systemic vascular resistance index (SVRI; P less than 0.05). Arteriovenous oxygen content difference (C(a-v)O2), O2 extraction ratio, mixed venous oxygen tension (PVO2), pH, and base deficit (BD) were not different from control values even during prolonged hypothermia. Normothermic control dogs also demonstrated a significant decrease in CI (P less than 0.05) at 24 h. Surface rewarming increased VO2 back to control values in the acute hypothermia group and to values above control (P less than 0.05) in the prolonged hypothermia group. DO2 remained below control in both groups, resulting in a significant increase in O2 extraction (P less than 0.05) and a decrease in PVO2 (P less than 0.05) in the prolonged hypothermia animals. Following rewarming administration of sodium nitroprusside returned DO2, CI, and SVRI to control values but did not increase VO2. All animals survived the study without need for inotropic support.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine receptor density and acetylcholinesterase activity in skeletal muscle of rats following thermal injury.

Thermal injury causes systemic changes that result in altered sensitivity to many drugs including nondepolarizing muscle relaxants. In an effort to identify the mechanism(s) responsible for the resistance to nondepolarizing muscle relaxants, the density of acetylcholine receptors (AChR) and the activity of acetylcholinesterase (AChE) were determined in rats following a 30% total body surface thermal injury at a time when resistance to atracurium is maximum. AChR density in gastrocnemius and diaphragm was unchanged by thermal injury. Furthermore, the ratio of junctional to extrajunctional AChR in diaphragm was unaltered. Total AChE activity was unchanged in thermally injured rats compared with that in sham-injured animals. Separation of the molecular forms of AChE by sucrose gradient centrifugation also showed no changes in the relative proportions of these species. The mechanism of resistance to nondepolarizing muscle relaxants does not appear to be explained by changes in AChR number or changes in the activity of AChE.

Perioperative rofecoxib plus local anesthetic field block diminishes pain and recovery time after outpatient inguinal hernia repair.

In this study, we compared pain scores after inguinal herniorrhaphy in patients treated by preincisional local anesthetic field block (PL), or PL combined with perioperative rofecoxib, with controls who received standard care. Seventy-five patients having herniorrhaphy under general anesthesia were randomly assigned to receive a placebo pill preoperatively, and for 5 days postoperatively (CONT); preoperative bupivacaine field block and perioperative placebo (PL); preoperative field block plus rofecoxib, 50 mg preoperatively and for 5 days postoperatively (PLR). Bupivacaine infiltration in the wound at closure, IV fentanyl and acetaminophen/oxycodone were administered postoperatively to all. Discharge time, pain scores (0–10), analgesic use, and satisfaction scores (1–6) were compared using analysis of variance. PLR patients had lower maximum pain scores (worst pain) in the postanesthesia care unit (3.7 versus 5.3, P = 0.02) and at 24 h (5.3 versus 6.8, P = 0.03), were discharged 38 min sooner (P = 0.01), required 28% less oxycodone 0–24 h after discharge (P = 0.04), and reported higher satisfaction scores compared with CONT. Pain in PL was less than CONT for 30 min. There were no differences among the 3 groups after 24 h postoperatively. We conclude that perioperative rofecoxib with PL reduces in-hospital recovery time, decreases pain scores and opioid use, and improves satisfaction scores in the first 24 h after surgery.