Randomized controlled pilot trial of the rigid and flexing laryngoscope versus the fiberoptic bronchoscope for intubation of potentially difficult airway.

BACKGROUND: The flexible fiberoptic bronchoscope (FOB) is viewed as the gold standard device for awake intubation in the difficult airway. The newer rigid flexible laryngoscope (RIFL) was developed for similar indications. In this study we compare these two devices for management of potentially difficult airways after induction of general anesthesia. METHODS: Adult surgical patients requiring endotracheal intubation and having a predicted difficult airway based on airway examination, BMI≥35, and/or history of prior difficult intubation were randomized to undergo endotracheal intubation with either the RIFL or FOB. Induction was performed in usual manner, and intubation was performed by providers proficient with both airway devices after induction of general anesthesia. The primary outcomes measured were intubation success, time to intubation, number of attempts, and the need for airway assist maneuvers. The lowest observed oxygen saturation and airway trauma were also recorded. RESULTS: A total of 41 patients were enrolled, with 20 randomized to each group and 1 withdrawal. Intubation was successful in all patients with both devices. The median time for successful intubation was significantly shorter in the RIFL group compared to the FOB group (49 vs. 64 seconds; P=0.048). Airway assist maneuvers were required in 2 (10%) intubations with the RIFL compared to 16 (80%) intubations with the FOB (P<0.001). There were no significant differences in lowest oxygen saturation or airway trauma. CONCLUSION: The RIFL required significantly less time and fewer airway assist maneuvers for successful endotracheal intubation compared to FOB when used by experienced providers in patients with anticipated difficult airways.

Comparison of two different temperature maintenance strategies during open abdominal surgery: upper body forced-air warming versus whole body water garment.

BACKGROUND: A new system has been developed that circulates warm water through a whole body garment worn by the patient during surgery. In this study the authors compared two different strategies for the maintenance of intraoperative normothermia. One strategy used a new water garment warming system that permitted active warming of both the upper and lower extremities and the back. The other strategy used a single (upper body) forced-air warming system. METHODS: In this prospective, randomized study, 53 adult patients were enrolled in one of two intraoperative temperature management groups during open abdominal surgery with general anesthesia. The water-garment group (n = 25) received warming with a body temperature (rectal) set point of 36.8 degrees C. The forced-air-warmer group (n = 28) received routine warming therapy using upper body forced-air warming system (set on high). The ambient temperature in the operating room was maintained constant at approximately 20 degrees C. Rectal, distal esophageal, tympanic, forearm, and fingertip temperatures were recorded perioperatively and during 2 h after surgery. Extubated patients in both groups were assessed postoperatively for shivering, use of additional warming devices, and subjective thermal comfort. RESULTS: The mean rectal and esophageal temperatures at incision, 1 h after incision, at skin closure, and immediately postoperatively were significantly higher (0.4-0.6 degrees C) in the group that received water-garment warming when compared with the group that received upper body forced-air warming. The calculated 95% confidence intervals for the above differences in core temperatures were 0.7-0.1, 0.8-0.2, 0.8-0.2, and 0.9-0.1, retrospectively. In addition, 14 and 7% of patients in the control upper body forced-air group remained hypothermic (< 35.5 degrees C) 1 and 2 h after surgery, respectively. No core temperature less than 35.5 degrees C was observed perioperatively in any of the patients from the water-garment group. A similar frequency of the thermal stress events (shivering, use of additional warming devices, subjective thermal discomfort) was observed after extubation in both groups during the 2 h after surgery. CONCLUSIONS: The investigated water warming system, by virtue of its ability to deliver heat to a greater percentage of the body, results in better maintenance of intraoperative normothermia that does forced-air warming applied only to the upper extremities, as is common practice.

Leptin reverses sucrose-conditioned place preference in food-restricted rats.

Previous studies have suggested that food restriction can modify performance in the conditioned place preference (CPP) paradigm. In the present study, we tested the hypotheses that food restriction would enhance the development of a CPP to low-calorie sucrose pellets and that peripheral leptin replacement in food-restricted animals would reverse this effect. Using a range of 45-mg sucrose pellets (0-15 pellets) as a reward, we observed that a significant place preference was conditioned in food-restricted, but not ad libitum-fed rats. This CPP was reversed either by treatment of food-restricted rats with the dopamine receptor antagonist alpha-flupenthixol (200 microg/kg ip) during the training protocol or by chronic subcutaneous replacement of leptin (125 microg/kg/day) that attenuated the food restriction-induced decrease of circulating leptin. We conclude that dopaminergic signaling and the fall of plasma leptin concentrations contribute to the CPP of food-restricted rats. This finding suggests that in addition to metabolic adaptations, hypoleptinemia results in behavioral adaptations during states of energy deprivation.

Geometrical constraints on the development of a diatom.

In a plane hexagonal array of pores such as occurs in Thalassiosira oestrupii and other related species of marine diatom, the presence of a single, exceptional pore near the center of the array can cause the distortion in the pattern in such a way that the pores tend to diminish in diameter D with increasing distance R from the center. By a simple mathematical argument it is shown that for large values of R/D the pore diameter D varies as R(-1/6). This decrease in pore diameter with distance may have some developmental consequences. The law is generalized to other types of pattern. The second type of constraint, related to the presence of outer boundaries, is also discussed.

Insulin and raclopride combine to decrease short-term intake of sucrose solutions.

We have previously reported that the hormone insulin can modulate synaptic function of dopamine neurons. To evaluate whether insulin can alter performance of a task which is dependent on intact dopaminergic signaling, we tested rats in a five minute lick rate task, with a range of concentrations of sucrose or oil solutions. Rats received either ip (t -15 min) saline or the D2 receptor antagonist raclopride (50 microg/kg), and intraventricular (t -4 h) saline or insulin (5 mU). Although ineffective on its own, insulin combined with raclopride treatment resulted in significant suppression of sucrose lick rates compared to the saline/saline group. The overall results are consistent with our hypothesis that insulin may modify performance in tasks that are dependent on dopaminergic signaling.

Data management for a perioperative medicine practice.

This article provides an overview of the possible uses of information technology to support a perioperative medicine service and describes the required investment for various solutions and the current issues confronted by the application of information technology in a health care environment. The extent to which a perioperative medicine practice requires information technology support for data management varies widely with the goals of the practice. The informational goals may range from the simple tracking of sentinel event rates or outcomes, such as ICU admission rates or hospital length of stay, to using a complete electronic medical record encompassing all aspects of patient care. Because the human and financial resource demand is orders of magnitude between these two extreme solutions, an honest assessment of the informational requirements and the available information technology support is a critical first step.

Anesthesia for periodontal surgery.

This article provides an informational overview of clinical anesthesia for periodontal procedures. Patient health status, physical evaluation, preoperative preparation issues, and anesthetic approaches are discussed. The unique technical challenges offered by periodontal procedures requires both the anesthetist and surgeon to fully consider their surgical goals and patient's needs. Selecting and providing the optimum anesthetic approach is at once both an art and science. In the final analysis, successful patient care is a function of thoughtful planning and operator skill.

The visual analog scale in the immediate postoperative period: intrasubject variability and correlation with a numeric scale.

UNLABELLED: The visual analog scale (VAS) has been used to assess the efficacy of pain management regimens in patients with acute postoperative pain, but its usefulness has not been confirmed in postoperative pain studies. We studied 60 subjects in the immediate postoperative period. The specific data collected were: VAS scores versus an 11-point numeric pain scale; repeatability in VAS scores over a short time interval; and change in VAS scores from one assessment period to the next versus a verbal report of change in pain. The correlation coefficients for VAS scores with the 11-point pain scale were 0.94, 0.91, and 0.95. The repeatability coefficients were 17.6, 23.0, and 13.5 mm. Of the 56 patients who completed all three assessments, only 16 (29%) had repeatability within 5 mm on all three. Some of the changes in VAS scores between assessments were in the direction opposite the verbally reported changes in pain (31%); however, most (92%) were within 20 mm. There was no correlation between the level of sedation, previous pain experience, anxiety, or anticipated pain with consistency in VAS scores. We conclude that any single VAS score in the immediate postoperative period should be considered to have an imprecision of +/- 20 mm. IMPLICATIONS: The visual analog scale was developed for assessing chronic pain but is often used in studies of postoperative pain. This study finds that the visual analog scale correlates well with a verbal 11-point scale but that any individual determination has an imprecision of +/- 20 mm.

Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial.

OBJECTIVE: To assess the relationship between body temperature and cardiac morbidity during the perioperative period. DESIGN: Randomized controlled trial comparing routine thermal care (hypothermic group) to additional supplemental warming care (normothermic group). SETTING: Operating rooms and surgical intensive care unit at an academic medical center. SUBJECTS: Three hundred patients undergoing abdominal, thoracic, or vascular surgical procedures who either had documented coronary artery disease or were at high risk for coronary disease. OUTCOME MEASURE: The relative risk of a morbid cardiac event (unstable angina/ischemia, cardiac arrest, or myocardial infarction) according to thermal treatment. Cardiac outcomes were assessed in a double-blind fashion. RESULTS: Mean core temperature after surgery was lower in the hypothermic group (35.4+/-0.1 degrees C) than in the normothermic group (36.7+/-0.1 degrees C) (P<.001) and remained lower during the early postoperative period. Perioperative morbid cardiac events occurred less frequently in the normothermic group than in the hypothermic group (1.4% vs 6.3%; P=.02). Hypothermia was an independent predictor of morbid cardiac events by multivariate analysis (relative risk, 2.2; 95% confidence interval, 1.1-4.7; P=.04), indicating a 55% reduction in risk when normothermia was maintained. Postoperative ventricular tachycardia also occurred less frequently in the normothermic group than in the hypothermic group (2.4% vs 7.9%; P=.04). CONCLUSION: In patients with cardiac risk factors who are undergoing noncardiac surgery, the perioperative maintenance of normothermia is associated with a reduced incidence of morbid cardiac events and ventricular tachycardia.

Adrenergic, respiratory, and cardiovascular effects of core cooling in humans.

The adrenergic, respiratory, and cardiovascular responses to isolated core cooling were assessed in awake human subjects. Mild core hypothermia was induced by intravenous infusion of 30 or 40 ml/kg of cold saline (4 degrees C) on 2 separate days. A warm intravenous infusion (30 ml/kg, 37 degrees C) was given on a third day as a control treatment. Mean norepinephrine concentration increased 400% and total body oxygen consumption increased 30% when core temperature decreased 0.7 degrees C. Mean norepinephrine concentration increased 700% and total body oxygen consumption increased 112% when core temperature decreased 1.3 degrees C. Core cooling was associated with peripheral vasoconstriction and increased mean arterial blood pressure, whereas heart rate was unchanged. Plasma epinephrine and cortisol concentrations were unchanged during core cooling. There were no changes in any measured parameter with the warm infusion. These findings suggest that mild hypothermia induced by isolated core cooling is associated with an adrenergic response characterized by peripheral sympathetic nervous system activation without a significant adrenocortical or adrenomedullary response. The respiratory and cardiovascular responses to core cooling are characterized by a shivering-induced increase in metabolic rate, norepinephrine-mediated peripheral vasoconstriction, and increased arterial blood pressure.

An expert-guided decision tree construction strategy: an application in knowledge discovery with medical databases.

With the steady growth in electronic patient records and clinical medical informatics systems, the data collected for routine clinical use have been accumulating at a dramatic rate. Inter-disciplinary research provides a new generation of computation tools in knowledge discovery and data management is in great demand. In this study, an expert-guided decision tree construction strategy is proposed to offer an user-oriented knowledge discovery environment. The strategy allows experts, based on their expertise and/or preference, to override inductive decision tree construction process. Moreover, by reviewing decision paths, experts could focus on subsets of data that may be clues to new findings, or simply contaminated cases.

Multivariate determinants of early postoperative oxygen consumption in elderly patients. Effects of shivering, body temperature, and gender.

BACKGROUND: Previous investigators have proposed that postoperative shivering may be poorly tolerated by patients with cardiopulmonary disease because of the associated significant increase in total-body oxygen consumption. However, the often-quoted 300-400% increase in oxygen consumption with shivering was derived from relatively few studies performed in a small number of younger persons specifically selected on the basis of clinically recognizable shivering. We hypothesized that the average elderly postoperative patient has a shivering response that is associated with a relatively small increase in total-body oxygen consumption. METHODS: One hundred eleven elderly patients (age > 60 yr) undergoing surgery were studied to assess the determinants of shivering and total-body oxygen consumption in the early postoperative period. Anesthetic technique, postoperative analgesia, and thermal management were controlled by protocol. The clinical variables associated with shivering and increased total-body oxygen consumption were determined by univariate and multivariate analyses. RESULTS: Mean total-body oxygen consumption in shivering patients was 38% greater than in nonshivering patients. Regardless of whether data from shivering patients were included in the analysis, oxygen consumption was directly proportional to mean body temperature. Despite similar core temperatures, men had a greater incidence of clinically recognizable shivering and greater total-body oxygen consumption than did women. CONCLUSIONS: The metabolic demands associated with postoperative shivering in elderly patients are less than those reported previously in younger persons. These findings suggest that if hypothermia predisposes to cardiovascular complications in the postoperative period, these complications are not likely to be mediated by shivering and increased metabolism.

The catecholamine, cortisol, and hemodynamic responses to mild perioperative hypothermia. A randomized clinical trial.

BACKGROUND: Unintended hypothermia occurs frequently during surgery and may have adverse effects on the cardiovascular system. Although the mechanisms responsible for the cardiovascular manifestations of hypothermia are unclear, it is possible that they are sympathetically mediated. In this prospective study, relationships between body temperature, the neuroendocrine response, and hemodynamic changes in the perioperative period were examined. METHODS: Seventy-four elderly patients, undergoing abdominal, thoracic, or lower extremity vascular surgical procedures, were randomly assigned to either "routine care" (n = 37) or "forced-air warming" (n = 37) groups. Throughout the intraoperative and early postoperative periods, the routine care group received standard thermal care, and the forced-air warming group received forced-air skin-surface warming. Core temperature, forearm minus fingertip skin-surface temperature gradient, and plasma concentrations of epinephrine, norepinephrine, and cortisol were measured throughout the perioperative period, and the two groups were compared. In addition, heart rate and arterial blood pressure were compared between groups. RESULTS: The routine care and forced-air warming groups did not differ with regard to age, sex, type of surgical procedures, anesthetic techniques, or postoperative analgesia. Mean core temperature was lower in the routine care group on admission to the postanesthetic care unit (routine care, 35.3 +/- 0.1 degree C; forced-air warming, 36.7 +/- 0.1 degree C; P = 0.0001) and remained lower during the early postoperative period. Forearm minus fingertip skin-surface temperature gradient (an index of peripheral vasoconstriction) was greater in the routine care group in the early postoperative period. The mean norepinephrine concentration (pcg/ml) was greater in the routine care group immediately after surgery (480 +/- 70 vs. 330 +/- 30, P = 0.02) and at 60 min (530 +/- 50 vs. 340 +/- 30, P = 0.002) and 180 min (500 +/- 80 vs. 320 +/- 30, P = 0.004) postoperatively. Mean epinephrine concentrations were not significantly different between groups. Mean cortisol concentrations were increased in both groups during the early postoperative period (P < 0.01), but the differences between groups were not significant. Systolic, mean, and diastolic arterial blood pressures were significantly higher in the routine care group. CONCLUSIONS: Compared with patients in the forced-air warming group, patients receiving routine thermal care had lower core temperatures, a greater degree of peripheral vasoconstriction, higher norepinephrine concentrations, and higher arterial blood pressures in the early postoperative period. These findings suggest a possible mechanism for hypothermia-related cardiovascular morbidity in the perioperative period.

Recovery from outpatient laparoscopic tubal ligation is not improved by preoperative administration of ketorolac or ibuprofen.

The analgesic efficacy of a single dose of ketorolac or ibuprofen given preoperatively was assessed in healthy outpatients undergoing general anesthesia for laparoscopic tubal ligation. Fifty patients were randomized to receive either ketorolac 60 mg intravenously (i.v.), ibuprofen 800 mg orally, or placebo in a double-blind manner. Anesthesia was induced with fentanyl 2 micrograms/kg, thiopental 5 mg/kg, and either vecuronium 0.1 mg/kg or succinylcholine 1.5 mg/kg i.v. and was maintained with nitrous oxide 67% in oxygen and isoflurane. Patients were assessed at 15-min intervals in the postanesthesia care unit (PACU) and treated for pain with i.v. morphine by protocol. Patients were evaluated for pain, analgesic requirements, side effects, and recovery times. After discharge, patients completed questionnaires to assess pain, analgesic use, and side effects 6 and 24 h postoperatively. Parenteral morphine was required in 80% of patients in the control group, and 73% of patients in both treatment groups, and the difference was not statistically significant. The dose of parenteral morphine required in the PACU was not different between the control (7 +/- 1.2 mg), ibuprofen (5.7 +/- 1.4 mg), and ketorolac (6.1 +/- 1.4 mg) groups. There was no difference between groups in terms of pain visual analog scale (VAS) scores, fatigue VAS scores, recovery times, or the incidence of postoperative nausea and vomiting. The preoperative administration of either parenteral ketorolac or oral ibuprofen did not decrease postoperative pain or side effects when compared to placebo in this outpatient population.