Timothy McDonald

Heart rate variability and plasma catecholamines in patients during opioid detoxification.

It has been shown that rapid opioid detoxification is associated with increased sympathetic activity (SYMP) and plasma catecholamines. Heart rate (HR) variability may provide a noninvasive method of evaluating withdrawal and sympathetic activation caused by the reversal of opioid binding in patients who are opioid dependent. The purpose of this study was to evaluate the relationship between HR variability and plasma catecholamines during opioid detoxification. Patients were anesthetized with propofol, intubated, paralyzed with rocuronium infusion, and ventilated. The bispectral index (BIS) of the electroencephalogram was recorded with the patient awake as well as during propofol anesthesia. SYMP was determined by power spectral analysis of HR variability. Plasma epinephrine and norepinephrine were measured at baseline propofol anesthesia and during naltrexone treatment in eight opioid-dependent patients. Nonopioid-dependent controls (n = 7) were monitored during surgery without naltrexone treatment or measurement of plasma catecholamines. Compared with an awake status, propofol anesthesia significantly decreased the BIS and SYMP in both groups of patients. Controls showed no change from baseline anesthetized levels during surgery. Plasma norepinephrine and epinephrine as well as SYMP increased 300 to 400% (P < .05) during naltrexone treatment in opioid-dependent patients, and the time to peak increase in plasma norepinephrine correlated with the increase in SYMP (r = 0.89, P < .01). These results confirm that opioid detoxification increases plasma catecholamines and SYMP in a similar manner. HR rate variability may provide a low-cost real-time noninvasive method of evaluating the reversal of opioid binding in opioid-dependent patients.

Experience with one-stage laryngotracheal reconstruction

Eight patients (ages 10 months to 5 years) underwent laryngotracheal reconstruction (LTR) without intraluminal stenting or tracheostomy. All patients had moderate to severe acquired or congenital subglottic stenosis. Six patients were tracheostomy-dependent prior to reconstruction. The other two children were intubated and would have required tracheostomy for airway control. LTR and decannulation/extubation were accomplished as a one-stage procedure. Autologous rib cartilage was used (anterior graft only--6 patients, anterior and posterior graft--3 patients) and patients were intubated for 7-10 days. Pulmonary complications from the week-long intubation and intensive care unit stay were common, but easily managed. Seven of eight patients were successfully decannulated/extubated.

Ultra-rapid opioid detoxification increases spontaneous ventilation

STUDY OBJECTIVE To evaluate the effect of ultra-rapid opioid detoxification on spontaneous respiration. DESIGN Prospective study. SETTING University of Illinois, Chicago, Hospital. PATIENTS 20 ASA physical status I and II patients undergoing ultra-rapid opioid detoxification, and 5 ASA physical status I and II control patients undergoing surgical procedures. INTERVENTIONS Ultra-rapid opioid detoxification patients were anesthetized with propofol, intubated, and spontaneously ventilating. Opioid detoxification was achieved by giving repeated increasing intragastric doses of naltrexone. Control patients were anesthetized with propofol and 70% nitrous oxide and were time-based controls for opioid detoxification. MEASUREMENTS AND MAIN RESULTS Respiratory rate and minute ventilation were measured and increased 80% to 100% during opioid detoxification (p < 0.05). Respiratory rate and minute ventilation did not change in controls. Oxygen consumption and carbon dioxide (CO2) production were measured in separate studies and increased during ultra-rapid opioid detoxification with increases in spontaneous ventilation, but not when the patients were paralyzed. CONCLUSIONS Spontaneous ventilation increases during opioid detoxification without a change in end-tidal CO2. An increase in metabolism is produced in opioid withdrawal that is mediated by elevated muscle activity.

Changes in cerebral blood flow velocity in children during sevoflurane and halothane anesthesia.

The purpose of this study was to evaluate arterial blood pressure and middle cerebral artery blood flow velocity in children during induction of anesthesia with sevoflurane. These measures were compared to findings in a control group anesthetized with halothane. Each child received mask induction of sevoflurane (n = 9) or halothane (n = 9) with 70% nitrous oxide in oxygen. Blood pressure was measured noninvasively by an oscillometric technique using a Dinamap. Blood flow velocity was measured using a transcranial Doppler with a 2-MHz probe. End-tidal CO2, nitrous oxide, and anesthetic concentrations were measured by a Datex Ultima Capnomac. Both sevoflurane (2.4%) and halothane (1.3%) combined with 70% nitrous oxide decreased blood pressure and increased cerebral blood flow velocity. Intubation increased blood pressure and further increased cerebral blood flow velocity with both anesthetic treatments. These results indicate that sevoflurane and halothane combined with nitrous oxide decrease blood pressure and increase cerebral blood flow velocity and suggest that sevoflurane produces cerebrovascular effects similar to those of halothane during anesthetic induction.

Patient Safety Event Reporting Expectation: Does it Influence Residents’ Attitudes and Reporting Behaviors?

Background Internal Medicine resident (IMR) physician reporting of patient safety events (PSEs) is suboptimal and may be related to poor attitudes toward reporting. Purpose The objective was to evaluate the impact of a PSE reporting expectation on the rates of reporting among IMRs. Methods In this prospective cohort study, IMRs were informed of an expectation to submit 1 or more PSE report per month based on the ACGME core competencies. The PSE reports were collected over 9 months and compared with a 4-month baseline before the expectation. Report quality and IMRs’ attitudes were also evaluated. Results There was a significant and initial increase in the total number of reports. However, the number of IMRs meeting the expectation of 1 or more report per month initially rose but was not sustained over the 9-month observational period. Report quality and IMRs attitudes toward reporting were positive but unchanged over time. Conclusions Although a reporting expectation increased the total number of reports, the majority of IMRs did not maintain a 1 or more PSE report per month despite positive attitudes.

Median EEG frequency is more sensitive to increases in sympathetic activity than bispectral index.

Sympathetic heart rate variability is correlated with the increase in plasma catecholamines during rapid opioid detoxification. We evaluated whether the bispectral index, median frequency, or 95% spectral edge of the electroencephalogram are sensitive to the sympathetic response seen during reversal of opioid dependence. Eight patients undergoing rapid opioid detoxification gave informed consent. Two-channel frontal electroencephalogram was measured. Sympathetic heart rate variability was measured in 256 second segments by Fourier transform of continuous heart rate and the low frequency segment (0.02-0.13 Hz) analyzed for sympathetic function. Patients were anesthetized with propofol infusion. After a 30-60 min steady state, naloxone was infused intravenously at a rate of 25 mg/30 min, followed by an infusion of 1 mg/hr. During induction of anesthesia, sympathetic heart rate variability decreased from 1.80 to 0.3, bispectral index from 86 to 47, median frequency from 10.2 to 3.4, spectral edge from 23.5 to 16.7 (all P<.05). During naloxone infusion, the median percent increase in sympathetic heart rate variability was 487% (P<.05), median frequency increased 163% (P<.05), bispectral index (10%), and spectral edge (7%) did not significantly change. The increase in median frequency was delayed compared to sympathetic heart rate variability and median frequency remained elevated after sympathetic heart rate variability returned to anesthetized baseline in 5 of 8 cases. Our results show that median frequency and sympathetic heart rate variability increase during opioid detoxification, but the time course of each response is different. Median frequency is a more sensitive electroencephalogram indicator of opioid reversal than bispectral index or spectral edge.

Simultaneous increases in respiration and sympathetic function during opiate detoxification.

This study evaluated the relationship between the sympathetic withdrawal response and increases in spontaneous ventilation during naltrexone treatment in opioid-dependent patients. Naltrexone was given in repeated increasing doses by orogastric tube to 16 opioid-dependent patients during propofol anesthesia. Sympathetic activity was evaluated in 64-second segments by low frequency heart rate variability (0.02-0.10 Hz) and minute ventilation was measured every 15 minutes. During naltrexone treatment, heart rate and blood pressure increased with no change in the electroencephalogram as measured by the bispectral index. Sympathetic activity increased five-fold and minute ventilation increased by 50% during naltrexone administration. There was a significant correlation between the time of the peak sympathetic response and peak ventilation (r = 0.83, p < 0.001). In three control patients, who received anesthesia for surgery without naltrexone treatment, no increases in sympathetic or respiratory parameters were seen. These results indicate that peak sympathetic and respiratory stimulation occur together during opiate receptor antagonism in opioid addicts.

Jet injector compared with oral midazolam for preoperative sedation in children

Background : This study compared onset of sedation and satisfaction with two needleless jet injectors with the oral route for the administration of midazolam.

Plasma Naltrexone During Opioid Detoxification

Abstract Orogastric naltrexone is used for opioid detoxification, but it is not known how gastric absorption affects plasma concentrations of the drug. We measured plasma naltrexone during orogastric naltrexone, given in repeated doses of 12.5 mg, 25 mg, 50 mg and 50 mg. Plasma naltrexone was measured after each naltrexone dose. The increase in plasma naltrexone was highly variable between patients during orogastric administration. Adequate detoxification was questioned in 4 of 10 patients because plasma naltrexone did not increase above 5 ng/ml. There was a negative correlation between plasma naltrexone and the presence of withdrawal symptoms on the day after the procedure (r = −0.78, P < 0.05). These results show that the increase in plasma naltrexone is variable during orogastric administration and this may impair successful detoxification.

Combining median electroencephalography frequency and sympathetic activity in an index to evaluate opioid detoxification in patients.

During rapid opioid detoxification, increased sympathetic activity and a greater median frequency (MF) of activity on electroencephalography (EEG) have been reported. The purpose of this study was to evaluate a new index for detoxification that combines sympathetic activity and MF data. After informed consent was obtained, eight patients were sedated with propofol. The MF of EEG activity derived from frontal electrodes was determined. Heart rate variability was evaluated in 256-second segments by power spectral analysis, and sympathetic activity was determined by the low frequency component. The Hoffman Index for narcotic detoxification was weighted 70% to sympathetic activity and 30% to MF to normalize the difference in scales and to provide adequate weight to the sympathetic component. Opioid detoxification was produced by infusion of 25 mg naloxone for 30 minutes, followed by a 24-hour infusion of 1 mg per hour. The MF showed a rapid increase during high-dose infusion of naloxone, but the peak response occurred 1 to 2 hours later. Sympathetic activation and the Hoffman Index increased more slowly after the start of naloxone infusion, but peak increases in all components occurred at approximately the same time. The peak increases in Hoffman Index (110% of baseline), MF (260%), and sympathetic activity (304%) during administration of naloxone were significant and correlated with respect to time (r = 0.89–0.94). The Hoffman Index showed an early increase related to MF and a well-defined peak response indicative of sympathetic and MF activity. The behavior of the Hoffman Index in relation to the MF and sympathetic activity more clearly indicated the onset of opioid detoxification and the maximum response to opioid reversal than did MF or sympathetic activity alone.