Midazolam attenuates ketamine-induced abnormal perception and thought process but not mood changes.

PURPOSE: To determine the effects of midazolam, 30 ngxmL(-1), on altered perception, mood, and cognition induced by ketamine. METHODS: After ketamine was administered to achieve target concentrations of 50, 100, or 150 ngxmL in 11 volunteers, perception, mood, and thought process were assessed by a visual analog scale. Mini-Mental State examination (MMSE) assessed cognition. Boluses of midazolam, 30, 14.5, and 12 microgxkg(-1), were injected every 30 min to maintain the plasma concentration at 30 ngxmL(-1), which was reached 30 min after each injection. RESULTS: Ketamine produced changes in perception about the body (P < 0.01, 0.001, and 0.0001 at 30, 60, and 90 min), surroundings (P < 0.01 and 0.0001 at 60 and 90 min), time (P < 0.002 and 0.0001 at 60 and 90 min), reality (P < 0.001 and 0.0001 at 60 and 90 min), sounds (P < 0.002 at 90 min), and meaning (P < 0.05 at 90 min). Subjects felt less energetic and clearheaded (P < 0.02 and 0.05) during ketamine, midazolam, and their co-administration. Ketamine impaired thought process (P < 0.003 and 0.0001 at 60 and 90 min). Ketamine and midazolam decreased mean total MMSE and recall scores (P < 0.001 for both). Co-administration reduced the number of subjects with perceptual (body, P < 0.01 and 0.001 at 30 and 60 min) and thought process abnormalities. Within the range of observation, co-administration did not affect the changes in mood or recall. CONCLUSION: Midazolam attenuates ketamine-induced changes in perception and thought process.

Small-dose ketamine enhances morphine-induced analgesia after outpatient surgery.

UNLABELLED: Small-dose ketamine may enhance the analgesic effect of opiates. We studied the effect of IV coadministration of small-dose ketamine 50-100 microg/kg with morphine 50 microg/kg on postoperative morphine requirements and pain in 140 patients undergoing outpatient surgery. Midazolam 1-2 mg was administered in the holding area. Anesthesia was induced with propofol 2-2.5 mg/kg and was maintained with desflurane in a nitrous oxide/oxygen mixture. Patients received morphine 50 microg/kg with placebo (Group 1, n = 35) or ketamine 50 microg/kg IV (Group 2, n = 35), 75 microg/kg IV (Group 3, n = 35), or 100 microg/kg IV (Group 4, n = 35) 15 min before the end of the operation. Pain and drowsiness were assessed using visual analog scales on arrival in the recovery room, then every 15 min until the time of discharge to phase 2 recovery (phase 1 recovery). Morphine consumption in Groups 3 and 4 was approximately 40% less than that in the control group (91+/-9 and 89+/-8 microg/kg vs. 145+/-9 microg/kg; P<0.05 for both). Pain scores in Groups 3 and 4 were approximately 35% less than those in the control group at all time periods (P<0.0001 for all). There was no significant group difference in drowsiness scores. Small-dose ketamine 75-100 microg/kg IV, enhanced morphine-induced analgesia after outpatient surgery. Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine. IMPLICATIONS: Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine.

Technology evaluation report: obtaining pulse oximeter signals when the usual probe cannot be used.

We studied the function of four different monitoring probes used with the Satlite pulse oximeter (Datex, Helsinki). The aim was to evaluate ease of use and compare the function of the probes and their attachment methods in different locations (finger, toe, ear, thumb web, instep, wrist, and ankle). Two similar pulse wave oximeters were used in the study. To select the best signal we determined the absolute height of the plethysmographic waveform for each probe. Probes were compared on awake normal adult volunteers (N = 13), in anesthetized adult patients (N = 12), and in neonates weighting 500-1000 g (N = 8). In all the adult trials, the clip-on finger probe was used as a reference, and probes taped or clipped onto the finger provided adequate signal from the ear or from the thumb web, however. In the neonates, taped-on probes were most satisfactory.

Cost-benefit analysis of nasal cannulae in non-tracheally intubated subjects.

We evaluated four nasal cannulae used to deliver oxygen and measure PETC02 in a non-tracheally intubated, healthy population. The effect of various oxygen flow rates on PETC02 and respiratory rate (RR), as well as the cost and relative patient comfort of the cannulae, was compared. In this controlled study, 20 healthy volunteers tested the cannulae using oxygen flow rates of 0 (breathing room air), 2, 4, and 6 L/min. The volunteers rated the comfort of each cannula on a scale from 1 (uncomfortable) to 10 (comfortable). Hospital costs of the cannulae were also compared. All of the cannulae, except the Hospitak nasal cannula (HOS), demonstrated an oxygen flow dependency with respect to PETC02 and RR. The HOS cannula was judged by the study population to be the most comfortable and was the second least expensive cannula tested. From a qualitative standpoint, the carbon dioxide waveform recorded with the HOS cannula was the one least affected by oxygen flow. Of the nasal cannula systems evaluated in this study, the HOS system demonstrated the best cost-benefit ratio, performing well clinically while being comfortable to wear and relatively inexpensive. These conclusions are specific to a healthy population and not to patients with lung disease,those who smoke, or those having a higher ASA classification status. Our evaluation suggests that comfort and clinical performance of nasal cannulae may well depend on device design.

A contextual-moderator analysis of emotional autonomy and adjustment in adolescence.

This study investigated the relation between emotional autonomy, as measured by Steinberg and Silverberg's Emotional Autonomy Scale (EA), and adolescent adjustment as moderated by several individual, familial, and cultural contexts. Subjects were 96 adolescents (10-18 years old) and their mothers and teachers. Results indicate that when the affective nature of the parent-adolescent relationship is positive (e.g., maternal warmth is high or intensity of parent-adolescent conflict is low), positive adolescent adjustment is more likely when adolescents report less emotional autonomy. On the other hand, when the family environment is more stressful, emotional autonomy is positively associated with adolescent adjustment. Findings suggest that higher scores on the EA scale index emotional detachment from parents and that such detachment is detrimental in supportive familial environments but adaptive in less supportive familial environments. That emotional detachment from parents appears to serve a protective function in certain stressful situations is viewed as analogous to the adoption of an avoidant attachment strategy during infancy.

Elective tracheostomy for a patient with a history of difficult intubation.

The anesthetic challenge of managing a difficult airway is demanding under the best of conditions. An emergency operation compounds the difficulty. Seldom do we have the opportunity to truly plan for a possible emergency. This report presents a solution to the problem of knowing of a difficult airway but having no control over the timing or possible emergent state of the operation.

Noninvasive evaluation of the collateral circulation to the hand.

OBJECTIVE: To compare four methods of evaluating collateral blood flow to the hand. METHODS: The hands of 74 volunteers on the faculty or staff of a university hospital were studied prospectively. Only subjects without known peripheral vascular disease were included. Four tests were used in random order to assess radial and ulnar artery flow. Results of the assessments using the modified Allen's test, pulse oximetry, plethysmography, and laser Doppler perfusion monitoring were compared. RESULTS: No interrupted palmar arch was found. The modified Allen's test was normal in all cases. Pulse oximetry detected a 5% incidence of noticeably reduced blood flow in one artery compared with the other artery. This dominance of one artery was identified in 69% of the hands by plethysmography. The laser Doppler noted a dominant artery in 64% of the hands. Plethysmography and the laser Doppler disagreed in their findings in only 9% of the hands evaluated. Numerical values of blood flow, attainable only by the laser Doppler, were significantly lower upon occlusion of the radial vs the ulnar arteries (p < 0.05; paired t-test). CONCLUSION: All of the tests provide information about the collateral circulation to the hand. Only the laser Doppler provides quantitative blood flow. Further studies involving subjects most at risk for post-cannulation ischemic injury are needed to guide the clinical application of these findings.

Patterns of prescribing and administering drugs for agitation and pain in patients in a surgical intensive care unit.

OBJECTIVES: To describe the variety of medications prescribed along with the doses administered and routes of administration, and to delineate the clarity of orders written and the accuracy of transcription of drugs used for sedation, anxiety, pain, and neuromuscular blockade in a surgical intensive care unit (ICU). DESIGN: A prospective, observational study of drug-related information collected from forms used by physicians and nurses. SETTING: Three adult surgical ICUs at an academic medical center. Patients were admitted to a surgical service and co-managed by the surgical ICU team and primary surgical service. PATIENTS: Consecutive patients admitted to all of these units from September 1992 to January 1993. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Information on prescribing and administering sedatives, analgesics, and neuromuscular blocking drugs was obtained from data collected on 221 patients. A total of 202 (91%) patients received, on average, 1.9 +/- 1.4 study drugs (range 0 to 9) in a wide variety of combinations. There were 2,103 total doses administered from 448 drug orders. Ninety percent of study drug orders were written for administration on an "as-needed" basis; in 42% of these orders, the indication for use was not specified. On average, only 27% of the maximal allowable daily dose was administered; this number ranged from 15% for hydromorphone to 77% for chlordiazepoxide. Morphine sulfate, the most commonly prescribed drug, was ordered primarily for intravenous administration in 84% of patients. Morphine sulfate was prescribed using 19 different doses (written as a range of doses) and 13 different dosing intervals. Transcription discrepancies were observed in 17% of orders. In 2.7% of doses, the actual dose that was administered could not be determined. CONCLUSIONS: A wide variety of sedatives and analgesics are frequently used in surgical ICU patients. These agents are often ordered on an "as-needed" basis using a range of doses, sometimes without adequate directions about the indication for their use. Daily doses received are significantly less than their maximum allowable daily doses. Orders for these medications are sometimes transcribed and charted incorrectly. In contrast, neuromuscular blocking agents are not commonly prescribed. Future studies are needed to improve order writing of these agents, and to determine the criteria used by physicians and nurses in the selection and administration of these agents, the outcomes of therapy, and the most cost-effective regimen.

Comparison of digital blood pressure, plethysmography, and the modified Allen's test as means of evaluating the collateral circulation to the hand.

The collateral circulation to the hand was evaluated on 70 hands of healthy volunteers. Comparisons were made between the results of the modified Allen's test alone and the Allen's test combined with either plethysmography or digital blood pressure. The modified Allen's test requires patient cooperation and the results can be subjective. Plethysmography does not require patient cooperation and produces a signal that varies directly with flow; however, this is not a quantifiable signal. Digital blood pressure (measured by the 2300 Finapres noninvasive blood pressure monitor, Ohmeda, Englewood, CO, USA) also requires no patient cooperation. The values produced are of clinical value and reproducible. Both the plethysmograph and digital blood pressure monitors were able to demonstrate the dominant arterial vessel of the hand. The digital blood pressure monitor produces an objective recordable numerical value, an accepted clinical parameter, and it does not require patient cooperation. The use of a digital blood pressure monitor may prove to be an acceptable alternative to the traditional Allen's test.

Comparison of the efficacy of esmolol and alfentanil to attenuate the hemodynamic responses to emergence and extubation.

STUDY OBJECTIVE: To define the ability of esmolol and alfentanil to control the hemodynamic changes associated with extubation and emergence. DESIGN: Randomized, double-blind, placebo-controlled study. SETTING: General surgery operating rooms at a university hospital. PATIENTS: Forty-two ASA physical status I and II patients without history of cardiac or pulmonary disease undergoing surgery not involving the cranium or thorax. INTERVENTIONS: Patients were given either a bolus dose of normal saline followed by an infusion of normal saline, a bolus dose of alfentanil 5 micrograms/kg followed by an infusion of normal saline, or a bolus dose of esmolol 500 micrograms/kg followed by an infusion of esmolol 300 micrograms/kg/min. MEASUREMENTS AND MAIN RESULTS: Emergency and extubation resulted in significant increases in heart rate (HR) and blood pressure (BP) in the placebo group. Alfentanil controlled the responses to emergence but prolonged the time to extubation (p < 0.05). Esmolol significantly controlled the responses to emergence and extubation (p < 0.05). CONCLUSIONS: Emergence and extubation after inhalation general anesthesia result in significant increases in BP and HR in healthy patients. An esmolol bolus dose and subsequent infusion significantly attenuated these responses. A small bolus dose of alfentanil minimized the responses to emergence but prolonged the time to extubation and was no longer protective at that point.

Evaluation of collateral circulation of the hand.

In 1929, Edgar V. Allen described a noninvasive evaluation of the patency of the arterial supply to the hand of patients with thromboangitis obliterans (Am J Med Sci 1929; 178:237). In the early 1950s, Allen's test was modified (Wright I. Vascular diseases in clinical practice. Chicago: Year Book Medical Publishers, 1952) for use as a test of collateral circulation prior to arterial cannulation. This test involves the examiner occluding the patient's ulnar and radial arteries while the patient makes a fist, causing the hand to blanch. The patient is then asked to extend the fingers. After the hand is open, the examiner releases the ulnar artery while continuing to maintain pressure on the radial artery. Adequate collateral circulation is felt to be indicated by return of normal color to the hand. The patient is instructed not to hyperextend the fingers when opening the hand. Hyperextension may cause a decrease in perfusion to the arch, possibly resulting in a false interpretation of the Allen test (Anesthesiology 1972;37:356). The modified Allen's test can be performed quickly and easily, but it is susceptible to error. (With Allen's original test, both hands were tested simultaneously. The patient clenched both fists tightly for 1 minute while the examiner compressed one artery of each hand. This method helps diagnose complete occlusion, just as Allen intended. The test was later modified, however, to evaluate the adequacy of collateral circulation. To perform the modified Allen's test, the examiner compresses both arteries while the patient's fist are clenched.(ABSTRACT TRUNCATED AT 250 WORDS)