Acute pulmonary edema in healthy teenagers following conservative doses of intravenous naloxone

Effectiveness of intramuscular naloxone 1,600 μg in addition to titrated intravenous naloxone 100 μg for opioid poisoning: a randomised controlled trial

INTRODUCTION

Naloxone is an effective antidote, but its short half-life means repeated doses, and infusions are often required. We investigated the effectiveness of adding intramuscular naloxone to titrated intravenous naloxone in opioid overdose in preventing recurrence of respiratory depression.

METHODS

This double-blinded randomised placebo-controlled trial was conducted in patients with suspected opioid poisoning and respiratory depression (respiratory rate <10 breaths/min or oxygen saturation <93%). Patients were randomised to receive either intramuscular naloxone 1,600 µg or saline placebo. All patients received titrated intravenous naloxone 100 µg and were managed on an opioid poisoning care pathway. The primary outcome was recurrence of respiratory depression within 4 h. Secondary outcomes were the proportion receiving naloxone infusions, number of naloxone boluses administered, reversal of respiratory depression at 10 min, and precipitation of opioid withdrawal (any symptom).

RESULTS

Recurrence of respiratory depression within 4 h was less common in 28/69 (41%) patients receiving intramuscular naloxone versus 48/67 (72%) patients receiving placebo (difference 31%, 95% CI: 13-46%; P < 0.001). Fewer naloxone infusions (5/69; 7% versus 25/67; 37%, difference 30%, 95% CI: 15 to 55%; P < 0.001) and fewer naloxone doses were administered (median 2, IQR: 1 to 5, versus median 5, IQR: 2 to 8; P = 0.001) in the intramuscular group. Reversal of respiratory depression at 10 min was similar between groups (51/69; 74% intramuscular naloxone versus 47/67; 70% placebo; P = 0.703). Opioid withdrawal occurred in 35/69 (51%) given intramuscular naloxone compared to 28/67 (42%) in the placebo group (difference 9%; 95% CI: -8 to 27%; P = 0.308).

DISCUSSION

The favourable pharmacokinetics of intramuscular naloxone, particularly its longer duration of activity, likely explains the improved effectiveness with lower recurrence of respiratory depression.

CONCLUSION

The addition of intramuscular naloxone 1,600 µg to titrated intravenous naloxone prolonged effective reversal of respiratory depression, with fewer naloxone doses and infusions given, and no significant difference in patients developing withdrawal.

Pulmonary edema after naloxone administration for opioid reversal: a systematic review of case reports and causality assessment using the Naranjo scale

INTRODUCTION

Pulmonary edema is a rare complication occurring after naloxone administration, but the causal relationship remains insufficiently investigated. We aimed to determine the likelihood of naloxone as the causative agent in published cases of pulmonary edema.

METHODS

A literature search was conducted across multiple databases, utilizing database-specific search terms such as "pulmonary edema/chemically induced" and "naloxone/adverse effects." Each case report was evaluated using the Naranjo scale, a standardized causality assessment algorithm.

RESULTS

We identified 49 published case reports of pulmonary edema following naloxone administration. The median total dose of naloxone was 0.2 mg for patients presenting following a surgical procedure and 4 mg for out-of-hospital opioid overdoses. Based on the Naranjo scale, the majority of cases were classified as "possible" (n = 38) or "probable" (n = 11) adverse reactions, while no "definite" cases of naloxone-induced pulmonary edema were identified. Many patients were classified as "possible" due to limited patient information or other potential risks, such as fluid administration or airway obstruction. Forty-six of 49 patients survived (94 percent).

DISCUSSION

Pulmonary edema may occur after both low and high doses of naloxone; however, low doses were primarily reported in the surgical population. Despite this complication, the majority of patients survived. Furthermore, no case report in our analysis was classified as a "definite" case of naloxone-induced pulmonary edema which limits the establishment of causality. Future studies should explore patient risk factors, including surgical versus outpatient setting and opioid-naïve versus opioid-tolerant for developing pulmonary edema and employ a causality assessment algorithm.

CONCLUSIONS

These case reports suggest pulmonary edema can occur following naloxone administration, irrespective of dose. According to the Naranjo scale, there were no definite cases of naloxone-induced pulmonary edema. Overall, we suggest the benefits of naloxone administration outweigh the risks. Naloxone should be administered to treat opioid overdoses while monitoring for the development of pulmonary edema.

Clinical Pharmacokinetics and Pharmacodynamics of Naloxone

Naloxone is a World Health Organization (WHO)-listed essential medicine and is the first choice for treating the respiratory depression of opioids, also by lay-people witnessing an opioid overdose. Naloxone acts by competitive displacement of opioid agonists at the μ-opioid receptor (MOR). Its effect depends on pharmacological characteristics of the opioid agonist, such as dissociation rate from the MOR receptor and constitution of the victim. Aim of treatment is a balancing act between restoration of respiration (not consciousness) and avoidance of withdrawal, achieved by titration to response after initial doses of 0.4-2 mg. Naloxone is rapidly eliminated [half-life (t1/2) 60-120 min] due to high clearance. Metabolites are inactive. Major routes for administration are intravenous, intramuscular, and intranasal, the latter primarily for take-home naloxone. Nasal bioavailability is about 50%. Nasal uptake [mean time to maximum concentration (Tmax) 15-30 min] is likely slower than intramuscular, as reversal of respiration lag behind intramuscular naloxone in overdose victims. The intraindividual, interindividual and between-study variability in pharmacokinetics in volunteers are large. Variability in the target population is unknown. The duration of action of 1 mg intravenous (IV) is 2 h, possibly longer by intramuscular and intranasal administration. Initial parenteral doses of 0.4-0.8 mg are usually sufficient to restore breathing after heroin overdose. Fentanyl overdoses likely require higher doses of naloxone. Controlled clinical trials are feasible in opioid overdose but are absent in cohorts with synthetic opioids. Modeling studies provide valuable insight in pharmacotherapy but cannot replace clinical trials. Laypeople should always have access to at least two dose kits for their interim intervention.

Comparison of rates of opioid withdrawal symptoms and reversal of opioid toxicity in patients treated with two naloxone dosing regimens: a retrospective cohort study

INTRODUCTION

When managing opioid overdose (OD) patients, the optimal naloxone regimen should rapidly reverse respiratory depression while avoiding opioid withdrawal. Published naloxone administration guidelines have not been empirically validated and most were developed before fentanyl OD was common. In this study, rates of opioid withdrawal symptoms (OW) and reversal of opioid toxicity in patients treated with two naloxone dosing regimens were evaluated.

METHODS

In this retrospective matched cohort study, health records of patients who experienced an opioid OD treated in two urban emergency departments (ED) during an ongoing fentanyl OD epidemic were reviewed. Definitions for OW and opioid reversal were developed a priori. Low dose naloxone (LDN; ≤0.15 mg) and high dose naloxone (HDN; >0.15 mg) patients were matched in a 1:4 ratio based upon initial respiratory rate (RR). The proportion of patients who developed OW and who met reversal criteria were compared between those treated initially with LDN or HDN. Odds ratios (OR) for OW and opioid reversal were obtained via logistic regression stratified by matched sets and adjusted for age, sex, pre-naloxone GCS, and presence of non-opioid drugs or alcohol.

RESULTS

Eighty LDN patients were matched with 299 HDN patients. After adjustment, HDN patients were more likely than LDN patients to have OW after initial dose (OR = 8.43; 95%CI: 1.96, 36.3; p = 0.004) and after any dose (OR = 2.56; 95%CI: 1.17, 5.60; p = 0.019). HDN patients were more likely to meet reversal criteria after initial dose (OR = 2.73; 95%CI: 1.19, 6.26; p = 0.018) and after any dose (OR = 6.07; 95%CI: 1.81, 20.3; p = 0.003).

CONCLUSIONS

HDN patients were more likely to have OW but also more likely to meet reversal criteria versus LDN patients.

Naloxone interventions in opioid overdoses: a systematic review protocol

BACKGROUND

North America is in the midst of an unabated opioid overdose epidemic due to the increasing non-medical use of fentanyl and ultra-potent opioids. Naloxone is an effective antidote to opioid toxicity, yet its optimal dosing in the context of fentanyl and ultra-potent opioid overdoses remains unknown. This review aims to determine the relationship between the first empiric dose of naloxone and reversal of toxicity, adverse events, and the total cumulative dose required among patients with undifferentiated opioid overdoses and those with suspected toxicity from ultra-potent opioids. Secondary objectives include evaluating the relationship between the cumulative naloxone dose and toxicity reversal and adverse events, among patients with undifferentiated opioid overdoses and those with suspected toxicity from ultra-potent opioids.

METHODS

To identify studies, we will search MEDLINE, Embase, CENTRAL, DARE, CDAG, CINAHL, Science Citation Index, multiple trial registries, and the gray literature. Included studies will evaluate patients with suspected or confirmed opioid toxicity from undifferentiated opioids and ultra-potent opioids, who received an empiric and possibly additional doses of naloxone. The main outcomes of interest are the relationship between naloxone dose and toxicity reversal and adverse events. We will include controlled and non-controlled interventional studies, observational studies, case reports/series, and reports from poison control centers. We will extract data and assess study quality in duplicate with discrepancies resolved by consensus or a third party. We will use the Downs and Black and Cochrane risk of bias tools for observational and randomized controlled studies. If we find sufficient variation in dose, we will fit a random effects one-stage model to estimate a dose-response relationship. We will conduct multiple subgroup analyses, including by type of opioid used and by suspected high and low prevalence of ultra-potent opioid use based on geographic location and time of the original studies.

DISCUSSION

Our review will include the most up-to-date available data including ultra-potent opioids to inform the current response to the opioid epidemic, addressing the limitations of recent reviews. We anticipate limitations relating to study heterogeneity. We will disseminate study results widely to update overdose treatment guidelines and naloxone dosing in Take Home Naloxone programs.

Naloxone dosage for opioid reversal: current evidence and clinical implications

Opioid-related mortality is a growing problem in the United States, and in 2015 there were over 33,000 opioid-related deaths. To combat this mortality trend, naloxone is increasingly being utilized in a pre-hospital setting by emergency personnel and prescribed to laypersons for out-of-hospital administration. With increased utilization of naloxone there has been a subsequent reduction in mortality following an opioid overdose. Reversal of opioid toxicity may precipitate an opioid-withdrawal syndrome. At the same time, there is a risk of inadequate response or re-narcotization after the administration of a single dose of naloxone in patients who have taken large doses or long-acting opioid formulations, as the duration of effect of naloxone is shorter than that of many opioid agonists. As out-of-hospital use of this medication is growing, so too is concern about effective but safe dosing.

Antidote Use in the Critically Ill Poisoned Patient

The proper use of antidotes in the intensive care setting when combined with appropriate general supportive care may reduce the morbidity and mortality associated with severe poisonings. The more commonly used antidotes that may be encountered in the intensive care unit ( N-acetylcysteine, ethanol, fomepizole, physostigmine, naloxone, flumazenil, sodium bicarbonate, octreotide, pyridoxine, cyanide antidote kit, pralidoxime, atropine, digoxin immune Fab, glucagon, calcium gluconate and chloride, deferoxamine, phytonadione, botulism antitoxin, methylene blue, and Crotaline snake antivenom) are reviewed. Proper indications for their use and knowledge of the possible adverse effects accompanying antidotal therapy will allow the physician to appropriately manage the severely poisoned patient.

Cardiorespiratory Effects of Naloxone in Children

BACKGROUND:

Data on the cardiorespiratory changes and complications following administration of naloxone in children are limited.

OBJECTIVE:

To evaluate the cardiorespiratory changes and complications following naloxone treatment in children.

METHODS:

The maximal changes in respiratory rate (RR), heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure, and any complications within 1 and 2 hours following naloxone were tabulated.

RESULTS:

One hundred ninety-five children received naloxone over 3 years. The mean ± SD age was 9.7 ± 6 years. The total doses of naloxone ranged from 0.01 to 7 mg (0.001–0.5 mg/kg body weight), with a median dose of 0.1 mg. Group 1 patients consisted of 11 6 (60%) children who were postoperative and had been given naloxone by an anesthesiologist; group 2 patients consisted of 79 (40%) children who received naloxone in the emergency department or pediatric intensive care unit. Patients in group 1 were older: 10.6 ± 5.3 versus 8.2 ± 6.7 years (p < 0.006), but received significantly lower doses of naloxone (0.09 ± 0.2 vs. 1.1 ± 0.76 mg; p < 0.001). When the entire cohort was evaluated, a significant increase in RR (15 ± 7 vs. 21 ± 8 breaths/min; p < 0.001), HR (102 ± 29 vs.107 ± 29 beats/min; p < 0.001), SBP (109 ± 17 vs. 115 ± 15 mm Hg; p < 0.001), and DBP (56 ± 10 vs. 60 ± 13 mm Hg; p < 0.001) within 1 hour following naloxone was noted. When the 2 groups were compared, only the changes in RR were greater in group 2 patients (6.8 ± 7.9 vs. 4.7 ± 5 breaths/min; p < 0.001) following naloxone. Systolic hypertension occurred in 33 of 195 (16.9%) of all patients, while diastolic hypertension occurred in 13 (6.6%) of all patients after naloxone. Only the incidence of diastolic hypertension was higher in group 2 compared with group 1 patients following naloxone (16% vs. 2%; p < 0.001). Hypertension resolved spontaneously. One child developed pulmonary edema and required positive pressure ventilation for 22 hours.

CONCLUSIONS:

Moderate increases in RR, HR, and BP occur after naloxone administration to children, but development of more serious complications is rare.

Conscious Intravenous Sedation in Dentistry: A Review of Current Therapy

Several sedation options are used to minimize pain, anxiety, and discomfort during oral surgery procedures. Minimizing or eliminating pain and anxiety for dental care is the primary goal for conscious sedation. Intravenous conscious sedation is a drug-induced depression of consciousness during which patients respond purposefully to verbal commands. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate as well as cardiovascular function. Patients must retain their protective airway reflexes, and respond to and understand verbal communication. The drugs and techniques used must therefore carry a broad margin of safety.

Risk predictors of opioid-induced critical respiratory events in children: naloxone use as a quality measure of opioid safety

BACKGROUND

Opioid-induced respiratory depression (OIRD) is a life-threatening complication of opioid therapy in children. Naloxone administration triggered by OIRD has been used to monitor safety of opioid therapy in adults. We used this trigger as a quality measure of opioid safety in hospitalized children to identify risk predictors of OIRD.

METHODS

We retrospectively reviewed medical records of 38 patients identified from the hospital risk management database as requiring naloxone for critical respiratory events between January 2010 and June 2012 for demographics, comorbidities, surgery, naloxone event details, and outcomes. These data were compared with baseline prevalence in contemporary patients followed by pain service, who did not receive naloxone, to calculate unadjusted odds ratios. Thematic classification of preventable events was undertaken based on analysis of each event.

RESULTS

The incidence of naloxone use among hospital inpatients, who received opioids at-least once, was 0.06% compared with 0.23% for patients on the pain service. A majority of naloxone events occurred in postoperative patients (n = 27/38, 71.1%) within the first 24 hours of surgery (n = 20/27, 75.1%) and in the critical care unit (50%). Patients undergoing airway surgeries had higher risk for OIRD (P = 0.01). Patient risk factors for naloxone use included age <1 year (P < 0.001), obstructive sleep apnea (P < 0.001), obesity (P = 0.019), being underweight (P < 0.0001), prematurity (P < 0.001), and developmental delay (P < 0.001). Majority of events (87%) were found to be preventable, which were classified into six main themes based on type of event.

CONCLUSION

OIRD is an important, albeit mostly preventable, complication of opioid therapy in children. Naloxone use can be used as a measure to track opioid safety in children, identify contributing factors, and formulate preventive strategies to reduce the risk for OIRD.

[Naloxone-induced pulmonary edema. Case report with review of the literature and critical evaluation]

A case of pulmonary edema after the administration of naloxone for laparoscopic splenectomy is reported. Previous reports of naloxone-induced pulmonary edema are listed and reviewed. The clinical course is compared to other forms of non-cardiogenic pulmonary edema. Uncertainty remains about the underlying pathophysiological process and the true impact of naloxone on the development of pulmonary edema.

Negative pressure pulmonary edema following naloxone administration in a patient with fentanyl-induced respiratory depression

Naloxone is commonly used to reverse narcotic intoxication. However, its use is not entirely free of hazards. For instance, pulmonary edema (PE) has been reported to arise with the mechanism of over-sympathetic discharge caused by release of cat-echolamine or central neurogenetic responses to narcotic reversal. Here, we report a healthy young patient who, after undergoing an uneventful uvulopalatopharyngo-plasty for obstructive sleep apnea hypopnea syndrome, developed PE following administration of naloxone. Fentanyl-induced respiratory depression was found during anesthesia emergence and thus naloxone was indicated for reversal. Unfortunately, upper airway obstruction-induced negative pressure PE occurred following naloxone administration. From this case, we suggest that a patent airway should be ascertained before naloxone administration for treating narcotic-induced respiratory depression.

Cardiovascular changes after naloxone administration in propofol-sedated piglets during opioid overdose

BACKGROUND

Naloxone is an opioid receptor antagonist. Even when used in modest doses, it has been associated with serious cardiopulmonary side-effects. In this experimental porcine study, we examined the cardiac effects of naloxone during an opioid overdose.

METHODS

Cardiac parameters, changes in the left ventricular compliance and the magnitude of catecholamine release were evaluated in eight spontaneously breathing piglets under propofol sedation. Cardiac parameters were recorded every 30 s and transthoracic echocardiography was used for the continuous assessment of cardiac performance. Respiratory arrest was induced by morphine (8 mg/kg). Ten minutes after morphine administration, naloxone (80 microg/kg) was injected intravenously. Every 5 min, arterial blood gases were measured and, every 10 min, a sample for the analysis of plasma catecholamines was drawn.

RESULTS

There were no statistically significant changes in left ventricular ejection fraction and no signs of pulmonary hypertension. There was a statistically significant increase in the mean arterial pressure immediately after naloxone administration and in norepinephrine concentration before naloxone administration. After naloxone administration, the plasma catecholamine levels decreased in all but one animal. Two animals developed cardiac arrest (pulseless electrical activity and ventricular fibrillation) shortly after receiving naloxone. Although they were both administered naloxone prematurely due to hypoxic bradycardia, naloxone could have contributed to the development of ventricular fibrillation.

CONCLUSION

Naloxone did not cause changes in ejection fraction or mean pulmonary artery pressure in hypoxic and hypercarbic conditions. After naloxone administration, the plasma catecholamine levels returned to baseline in all but one animal, and two animals developed cardiac arrest.

Naloxone during neonatal resuscitation: acknowledging the unknown

There are no studies to support or to refute the current recommendations regarding naloxone concentration, routes for administration, and doses in neonatal resuscitation in the delivery room. Given the lack of supporting evidence, naloxone should not be given routinely in the delivery room to depressed neonates whether or not they are exposed to opioids before delivery because no important improvement has been documented and the drug may have potential short- and long-term harmful effects.

Naloxone in opioid poisoning: walking the tightrope

Acute opioid intoxication and overdose are common causes of presentation to emergency departments. Although naloxone, a pure opioid antagonist, has been available for many years, there is still confusion over the appropriate dose and route of administration. This article looks at the reasons for this uncertainty and undertakes a literature review from which a treatment algorithm is presented.

Naloxone for shock

BACKGROUND

There is pre-clinical evidence, involving several animal species, suggesting that opioid peptides play a role in the physiopathology of shock (endotoxic, hypovolemic, cardiogenic, spinal, anaphylactic). Many case reports have suggested that naloxone (an opiate antagonist) might be an effective treatment for shock in humans, but others have not supported such a point of view. This controversy led us to undertake a meta-analysis of the available evidence on the efficacy of naloxone as a treatment measure of shock in humans.

OBJECTIVES

To evaluate the effectiveness and safety of naloxone in human shock and to estimate the methodological quality of the clinical trials.

SEARCH STRATEGY

Computerized bibliographic search up to December 2002, review of references of all papers found on the subject and contact with primary investigators of eligible studies.

SELECTION CRITERIA

Randomized controlled trials evaluating naloxone in human shock, regardless of the patient's age (adult, child or neonate).

DATA COLLECTION AND ANALYSIS

Three independent reviewers extracted data on study design, intervention, outcome and methodological quality.

MAIN RESULTS

Three independent readers reviewed 80 human publications and selected six clinical trials. Overall agreement on study selection was perfect (concordance: 100%). This meta-analysis includes six studies involving 126 patients with septic, cardiogenic, hemorrhagic or spinal shock. Naloxone therapy was associated with statistically significant hemodynamic improvement (odds ratio 0.24; 95% confidence interval [95%CI] 0.09-0.68). The mean arterial pressure was significantly higher in the naloxone groups than in the placebo groups (weighted mean difference: +9.33 mmHg; 95%CI 7.07-11.59). No heterogeneity was found for this outcome. The death rate was lower in the naloxone group (odds ratio 0.59; 95%CI 0.21-1.67) but this was consistent with the play of chance. A significant heterogeneity for the latter outcome was detected (p<0.05).

REVIEWER'S CONCLUSIONS

Naloxone improves blood pressure, especially mean arterial blood pressure. However, the clinical usefulness of naloxone to treat shock remains to be determined, and additional randomized controlled trials are needed to assess its usefulness.

Early discharge of patients with presumed opioid overdose: development of a clinical prediction rule

OBJECTIVE

To develop a clinical prediction rule to identify patients who can be safely discharged one hour after the administration of naloxone for presumed opioid overdose.

METHODS

Patients who received naloxone for known or presumed opioid overdose were formally evaluated one hour later for multiple potential predictor variables. Patients were classified into two groups: those with adverse events within 24 hours and those without. Using classification and regression tree methodology, a decision rule was developed to predict safe discharge.

RESULTS

Clinical findings from 573 patients allowed us to develop a clinical prediction rule with a sensitivity of 99% (95% CI = 96% to 100%) and a specificity of 40% (95% CI = 36% to 45%). Patients with presumed opioid overdose can be safely discharged one hour after naloxone administration if they: 1) can mobilize as usual; 2) have oxygen saturation on room air of >92%; 3) have a respiratory rate >10 breaths/min and <20 breaths/min; 4) have a temperature of >35.0 degrees C and <37.5 degrees C; 5) have a heart rate >50 beats/min and <100 beats/min; and 6) have a Glasgow Coma Scale score of 15.

CONCLUSIONS

This prediction rule for safe early discharge of patients with presumed opioid overdose performs well in this derivation set but requires validation followed by confirmation of safe implementation.

Transnasal butorphanol for the treatment of opioid-induced pruritus unresponsive to antihistamines

Pruritus is a common opioid side effect and can be so severe that opioid therapy must be modified or abandoned. Antihistamines, opioid antagonists, and propofol have been proposed as treatment options, but none is universally effective. The use of intranasal butorphanol, an opioid agonist-antagonist, for pruritus has not been described previously. Six patients complaining of severe opioid-induced pruritus unresponsive to diphenhydramine received 2 mg intranasal butorphanol every 4-6 hr. Scores for pruritus, pain, and sedation were recorded on separate visual analogue scales (VAS). All patients reported significant relief from pruritus 60 min after butorphanol administration (P < 0.001); five patients noted an improvement within 15 min (P < 0.08). Sedation and pain VAS scores were not significantly different from baseline at all time points. These preliminary data demonstrate a substantial effect of intranasal butorphanol on opioid-induced pruritus that has not responded to antihistamines. Prospective controlled studies are needed to validate these findings.

Naloxone--for intoxications with intravenous heroin and heroin mixtures--harmless or hazardous? A prospective clinical study

BACKGROUND

Naloxone is standard medication for the treatment of heroin intoxications. No large-scale studies have yet been carried out to determine its toxicity in heroin intoxications.

METHODS

We have undertaken an investigation as to the frequency, type and degree of severity of complications attributable to naloxone administration. Subjects treated between 1991 and 1993 with naloxone for intravenous drug intoxications were prospectively evaluated.

MAIN OUTCOME MEASUREMENTS

Development of ventricular tachycardia or fibrillation; atrial fibrillation; asystole; pulmonary edema; convulsions; vomiting; and violent behavior within ten minutes after parenteral administration of naloxone.

RESULTS

Six of 453 intoxicated subjects (1.3%; 95% confidence interval 0.4%-3%) suffered severe adverse effects within ten minutes after naloxone administration (one asystole; three generalized convulsions; one pulmonary edema; and one violent behavior). After the ten minute period, no further complications were observed.

CONCLUSIONS

The short time between naloxone administration and the occurrence of complications, as well as the type of complications, are strong evidence of a causal link. In 1000 clinically diagnosed intoxications with heroin or heroin mixtures, from 4 to 30 serious complications can be expected. Such a high incidence of complications is unacceptable and could theoretically be reduced by artificial respiration with a bag valve device (hyperventilation) as well as by administering naloxone in minimal divided doses, injected slowly.

Opioid use in HIV patients with neurological changes

The neurological changes that are common in the HIV population may complicate the use of analgesics, particularly opioids. These changes, in combination with care providers' fear of opioids, often lead to the inappropriate use of antagonists, such as naloxone. Used injudiciously, naloxone can lead to withdrawal syndrome, return of severe pain, and other adverse effects. The authors describe the many disease and treatment-related causes for pain in patients with HIV disease, as well as common neurologic conditions that alter cognition and complicate the use of opioids. A case study is included to illustrate the dangers of inappropriate naloxone use.

A comprehensive review of naloxone for the emergency physician

Naloxone has enjoyed long-standing success as a safe and effective opioid antagonist and has been invaluable in defining the role of endogenous opioid pathways in the response to pathological states such as sepsis and hypovolemia. We look forward to exciting research to further elucidate these pathways and to improve outcome by modulating the patient's physiological response to these stresses.

Butorphanol tartrate for partial reversal of oxymorphone-induced postoperative respiratory depression in the dog

A randomized, blinded, crossover study was designed to evaluate the respiratory, cardiovascular, and behavioral effects of butorphanol given postoperatively to oxymorphone-premedicated and surgically stimulated dogs. Nine healthy adult dogs were premedicated intramuscularly with atropine (0.04 mg/kg), acepromazine (0.10 mg/kg), and oxymorphone (0.2 mg/kg). Anesthesia was induced with thiamylal (12 mg/kg) and maintained with halothane in oxygen. According to the protocol of a concurrent study, all dogs had percutaneous endoscopic gastrostomy (PEG) feeding tubes placed during the first anesthetic episode and removed during the second anesthetic episode. All dogs received postoperatively either butorphanol tartrate (0.2 mg/kg) or an isovolumetric dose of saline placebo, both given intravenously. Respiratory rate (RR), tidal volume (TV), minute ventilation (MV), end-tidal CO2 concentration (ETCO2), heart rate (HR), and indirect diastolic (DP), systolic (SP) and mean arterial (MAP) blood pressures were measured at times 0, 2, 5, 10, 20, 40, 80, and 120 minutes after injection. The time from injection of the test drug until extubation was recorded. RR, MV, HR, and DP were significantly (P < .05) increased, while ETCO2 was significantly decreased, for a minimum of 30 minutes in butorphanol-treated dogs compared with saline controls. TV, SP, and MAP were transiently (< or = 15 minutes) increased in butorphanol-treated dogs compared with saline controls. There was no significant difference between the times to extubation in the butorphanol-treated dogs versus the saline control dogs.

Acute myocardial infarction presenting as flank pain and tenderness: report of a case

Studies have demonstrated that 4% to 10% of patients with chest pain and acute myocardial infarction (AMI) are discharged from the emergency department. The patient with an atypical presentation of AMI is difficult to diagnose and has been demonstrated to have an associated increased risk of morbidity and mortality. A case is reported of a patient with AMI presenting to the emergency department with flank pain and tenderness, mimicking acute renal colic.

The empiric use of naloxone in patients with altered mental status: a reappraisal

STUDY OBJECTIVE

To determine whether clinical criteria (respirations of 12 or less, mitotic pupils, and circumstantial evidence of opiate abuse) could predict response to naloxone in patients with acute alteration of mental status (AMS) and to evaluate whether such criteria predict a final diagnosis of presence or absence of opiate overdose as accurately as response to naloxone.

CASES AND SETTING

Seven hundred thirty patients with AMS who received naloxone for diagnostic or therapeutic purposes at the discretion of two large, urban, paramedic base teaching hospitals.

METHODS

We reviewed paramedic run sheets and audiotapes on all 730 patients as well as available hospital records of all patients who demonstrated any response to naloxone to determine whether overdose was responsible for their clinical presentations. We also reviewed hospital records for a selected sample of naloxone nonresponders.

MAIN RESULTS AND CONCLUSION

Only 25 patients (3.4%) demonstrated a complete response to naloxone, whereas 32 (4.4%) manifested a partial or equivocal response. Nineteen of 25 complete responders (76%), two of 26 partial responders (8%) (with known final diagnosis), and four of 195 non-responders (2%) (with known final diagnosis) were ultimately diagnosed as having overdosed. Respirations of 12 or less or the presence of any one of the three clinical findings as a group were each highly sensitive in predicting response to naloxone, and at least as sensitive as response to naloxone in predicting a diagnosis of opiate overdose. Selective administration of naloxone for AMS would have decreased the use of this drug by 75% to 90% while still administering it to virtually all naloxone responders who had a final diagnosis of opiate overdose.

Refusal of care and discharging 'difficult' patients from the emergency department

Patients generally have the right to refuse medical care, a right based on certain legal precedents. Its application in the emergency department leads to difficult decisions for the emergency physician. A model that allows the emergency physician to determine the capacity of a patient to refuse care is presented. Certain types of patients regularly present problems in their treatment. These include psychiatric patients, narcotics abusers, alcoholics, "street people," and some patients with migraine headaches. They represent some of our most difficult decisions because the treatment required for the patient is often clear and the patient refuses care or demands inappropriate care.

Naloxone administration and laryngospasm followed by pulmonary edema

A 50-year-old woman underwent laryngoscopy. Postoperatively she received naloxone and was extubated. She developed severe laryngospasm and one hour later pulmonary edema. Both naloxone administration and laryngospasm can provoke pulmonary edema; the pathophysiology is discussed. It is suggested that naloxone is administered with care to patients who in the preceding hours have had severe laryngospasm.

Narcotic reversal in hypercapnic dogs: comparison of naloxone and nalbuphine

Reversal of opioid effects by naloxone (NX) can lead to significant cardiovascular problems. We have reported previously that hypercapnic dogs develop greater increases in blood pressure and plasma catecholamine (CA) levels than hypocapnic ones when reversed with naloxone. We have also demonstrated differences between NX and nalbuphine (NBPH) in producing excitatory adrenergic responses when administered during normocapnia. The present study was designed to investigate possible dissimilarities in cardiovascular and sympathetic events after administration of either NX or NBPH in dogs made hypercapnic following fentanyl administration. After induction of anaesthesia with thiopentone and intubation, two groups of dogs were maintained with controlled ventilation on enflurane in oxygen anaesthesia and given 50 micrograms.kg-1 fentanyl IV. This caused a significant decrease in heart rate (HR) (P less than 0.001), mean arterial blood pressure (MAP) (P less than 0.001), and plasma concentrations of norepinephrine (NE) (P less than 0.002). Then, ventilation was decreased to produce a PaCO2 of 60 mmHg; this was accompanied by a significant elevation in plasma level of both epinephrine (EPI) (P less than 0.02) and NE (P less than 0.001). Administration of 20 micrograms.kg-1 NX to six dogs resulted in immediate increases in HR (P less than 0.01) and MAP (P less than 0.01), and a further rise in CA levels to greater than pre-fentanyl baseline values. In six other dogs, NBPH (0.3 mg.kg-1) caused increases in HR (P less than 0.001) and MAP (P less than 0.001) only, and the MAP rise was significantly less than that seen in the NX group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxic cardiomyopathy: acute myocardial dysfunction after severe hypoxia

Five cases of acute transient myocardial dysfunction in previously well people after severe hypoxic episode are described. In all cases the hypoxic episode was associated with drug overdose and its complications. Pulmonary infiltrates on chest X-ray consistent with pulmonary edema developed in four cases and gated heart pool scanning confirmed severe cardiovascular dysfunction in all cases.

Prevention of epidural morphine-induced respiratory depression with intravenous nalbuphine infusion in post-thoracotomy patients

The efficacy of nalbuphine, an agonist/antagonist opioid, in preventing respiratory depression from epidural morphine analgesia after thoracotomy, was assessed in a randomized double-blind placebo controlled trial. After a standardized general anaesthetic and 0.15 mg.kg-1 of epidural morphine, patients received a bolus and then a 24 h infusion of nalbuphine (200 micrograms.kg-1 + 50 micrograms.kg-1.hr-1, 100 micrograms.kg-1 + 25 micrograms.kg-1.hr-1, or 50 micrograms.kg-1 + 12.5 micrograms.kg-1.hr-1) or placebo. Blood gases, analgesia, sedation, side effects, and blood nalbuphine concentrations were assessed every two hours for the next 24 h. Fifty-three per cent of placebo-treated patients had a PaCO2 greater than 50 mmHg and 89 per cent of these received naloxone. A 200 micrograms.kg-1 bolus of nalbuphine followed by a 50 micrograms.kg-1.hr-1 infusion achieved a mean steady state blood level of 38.2 ng.ml-1 and prevented CO2 retention greater than 50 mmHg in all but two patients, neither of whom required naloxone. There was no difference in the incidence of side effects among groups, and analgesia appeared to be unaffected by nalbuphine.