Acute propoxyphene self-poisoning in 222 consecutive patients

Cardiovascular Complications of Opioid Use: JACC State-of-the-Art Review

Opioids are the most potent of all analgesics. Although traditionally used solely for acute self-limited conditions and palliation of severe cancer-associated pain, a movement to promote subjective pain (scale, 0 to 10) to the status of a "fifth vital sign" bolstered widespread prescribing for chronic, noncancer pain. This, coupled with rising misuse, initiated a surge in unintentional deaths, increased drug-associated acute coronary syndrome, and endocarditis. In response, the American College of Cardiology issued a call to action for cardiovascular care teams. Opioid toxicity is primarily mediated via potent μ-receptor agonism resulting in ventilatory depression. However, both overdose and opioid withdrawal can trigger major adverse cardiovascular events resulting from hemodynamic, vascular, and proarrhythmic/electrophysiological consequences. Although natural opioid analogues are devoid of repolarization effects, synthetic agents may be proarrhythmic. This perspective explores cardiovascular consequences of opioids, the contributions of off-target electrophysiologic properties to mortality, and provides practical safety recommendations.

Overdose of Dologesic with a Fatal Outcome: A Case Report

Dologesic is a commonly prescribed analgesic in accident and emergency department. Yet report of overdose with this drug is not common. We report a case in which the patient developed cardiac arrest within an hour of ingestion. Dextropropoxyphene, a component of the drug Dologesic, used to be a common cause of fatalities after drug overdose in the seventies. It is highly toxic in overdose and therefore caution should be exercised when prescribing this drug.

Neurotoxic emergencies

This article is intended for clinicians treating neurotoxic emergencies. Presented are causative agents of neurotoxic emergencies, many of which are easily mistaken for acute psychiatric disorders. Understanding the wide variety of agents responsible for neurotoxic emergencies and the neurotransmitter interactions involved will help the psychiatrist identify and treat this challenging population.

Propoxyphene and the risk of out-of-hospital death

PURPOSE

The opioid analgesic propoxyphene was withdrawn from the US market in 2010, motivated by concerns regarding fatality in overdose and adverse cardiac effects, including prolongation of the QT interval. These concerns were based on case reports, summary vital statistics, and surrogate endpoint studies.

METHODS

Using the linked Tennessee Medicaid database (1992-2007), we conducted a retrospective cohort study that compared risk of sudden cardiac, medication toxicity, and total out-of-hospital death for propoxyphene users with that for comparable nonusers of any prescribed opioid analgesic and users of hydrocodone, an opioid with similar indications. Cohort members had 1,873,500 propoxyphene prescriptions, 1,873,500 matched nonuser control periods, and 936,750 matched hydrocodone prescriptions.

RESULTS

Current propoxyphene users had no increased risk for sudden cardiac death (versus nonusers: hazard ratio [HR] = 1.00 [0.81-1.23]; versus current hydrocodone users: HR = 0.91 [0.68-1.21]) but did have increased risk for medication toxicity deaths (versus nonusers: HR = 1.85 [1.07-3.19], p = 0.027; versus current hydrocodone users: HR = 2.10 [0.87-5.10], p = 0.100). Because toxicity deaths were a small proportion of study deaths, total out-of-hospital mortality differed by less than 10% between the study groups and was not significantly elevated for propoxyphene (versus nonusers: HR = 1.09 [0.95-1.25]; versus current hydrocodone users: HR = 1.06 [0.87-1.29] ).

CONCLUSIONS

Our findings support the concern that propoxyphene has greater toxicity in overdose but do not provide evidence that it increases the risk of sudden cardiac death.

Validation of a computer case definition for sudden cardiac death in opioid users

BACKGROUND

To facilitate the use of automated databases for studies of sudden cardiac death, we previously developed a computerized case definition that had a positive predictive value between 86% and 88%. However, the definition has not been specifically validated for prescription opioid users, for whom out-of-hospital overdose deaths may be difficult to distinguish from sudden cardiac death.

FINDINGS

We assembled a cohort of persons 30-74 years of age prescribed propoxyphene or hydrocodone who had no life-threatening non-cardiovascular illness, diagnosed drug abuse, residence in a nursing home in the past year, or hospital stay within the past 30 days. Medical records were sought for a sample of 140 cohort deaths within 30 days of a prescription fill meeting the computer case definition. Of the 140 sampled deaths, 81 were adjudicated; 73 (90%) were sudden cardiac deaths. Two deaths had possible opioid overdose; after removing these two the positive predictive value was 88%.

CONCLUSIONS

These findings are consistent with our previous validation studies and suggest the computer case definition of sudden cardiac death is a useful tool for pharmacoepidemiologic studies of opioid analgesics.

Drugs of abuse: the highs and lows of altered mental states in the emergency department

The diagnosis and management of poisoned patients presenting with alterations in mental status can be challenging, as patients are often unable (or unwilling) to provide an adequate history. Several toxidromes exist. Recognition hinges upon vital signs and the physical examination. Understanding these "toxic syndromes" may guide early therapy and management, providing insight into the patient's underlying medical problem. Despite toxidrome recognition guiding antidotal therapy, the fundamental aspect of managing these patients involves meticulous supportive care. The authors begin with a discussion of various toxidromes and then delve into the drugs responsible for each syndrome. They conclude with a discussion on drug-facilitated sexual assault ("date rape"), which is both an underrecognized problem in the emergency department (ED) and representative of the drug-related problems faced in a modern ED.

Outcome after heroin overdose and cardiopulmonary resuscitation

BACKGROUND

The survival of heroin overdose patients resuscitated from cardiac arrest is reported to be poor. The aim of our study was to investigate the outcome and characteristics of survivors after cardiac arrest caused by heroin overdose.

METHODS

This was a retrospective study in a medium-sized city (population, 560,000). Between 1 January 1997 and 31 December 2000, there were 94 combined cardiac arrests caused by acute drug poisonings. The main outcome measure was survival to discharge.

RESULTS

Cardiopulmonary resuscitation was attempted in 19 heroin overdose patients (group A) and in 53 patients with cardiac arrest caused by other poisonings (group B). Three (16%) vs. six (11%) patients were discharged alive (group A vs. B, respectively). The survivors in group A had an Emergency Medical Service (EMS)-witnessed cardiac arrest or the Emergency Dispatching Centre was called before the arrest occurred. There was no statistically significant difference between the two groups in terms of survival. Survivors in both groups suffered from acute renal failure (two), hypoglycaemia (four) and hypothermia (three).

CONCLUSION

Survival after cardiac arrest caused by heroin overdose is possible if the arrest is EMS witnessed or the Emergency Dispatching Centre is called before the cardiac arrest occurs. In comparison with cardiac arrests caused by other poisonings, there was no difference in survival. The incidence and mechanism of hypoglycaemia should be examined in further studies.

Pain management today—what have we learned?

Pain is a leading cause of morbidity worldwide, with published data showing its prevalence as high as 50% for chronic pain in the European population. This prevalence is likely to continue to rise, particularly in elderly people with comorbid conditions and complex aetiologies of pain. There is thus a rapidly growing demand for safe and effective pain management. Management of mild-to-moderate pain has traditionally been based upon the use of non-steroidal anti-inflammatory drugs (NSAIDs) and the synthetic non-opioid analgesic paracetamol (acetaminophen), the latter of which acts centrally, inhibiting brain cyclo-oxygenase (COX) and nitric oxide synthase. Both the NSAIDs and paracetamol are effective for mild-to-moderate pain and are widely recommended and used. However, NSAIDs may not be tolerated due to gastrointestinal (GI) symptoms and can result in potentially fatal peptic ulceration and bleeding. Selective COX-2 inhibitors were developed to reduce the GI side effects and complications, but large-scale studies have highlighted another serious potential effect of anti-inflammatory drugs: cardiovascular events. Both the European Medicines Agency (EMEA) and the Food and Drugs Administration (FDA) in the US have issued advice to apply cautions and restrictions when prescribing COX-2 inhibitors, particularly for patients at increased cardiovascular risk and for long-term use. The FDA also applied cardiovascular warnings with regard to nonselective NSAIDs. Both the EMEA and the FDA have recommended using the lowest effective dose for the shortest duration. These concerns and warnings have left physicians seeking safe alternatives to anti-inflammatory drugs for both short- and long-term uses in many patients. These developments have generated a climate of uncertainty in the absence of official guidance on the selection of alternative analgesic regimens. Amongst the possible strategies, combinations of drugs that provide analgesic efficacy at reduced individual doses may confer the optimal risk-benefit ratio for pain management in the long term or in patients at increased cardiovascular risk. Weak opioids devoid of serious organ-damaging effects combined with paracetamol may well be safer for long-term therapy. Fixed-dose combinations of paracetamol with weak opioids, such as codeine, dextropropoxyphene or tramadol are currently available. Paracetamol plus tramadol is an effective and safe multimodal analgesic regimen for the management of both acute and chronic moderate-to-severe pain. Re-evaluating the role of weak opioids, such as tramadol, and combinations in pain management may prove a valuable option for prescribers seeking alternatives to anti-inflammatory drugs.

Pharmacological aspects of successful long-term analgesia

Persistent pain represents a major quality-of-life burden for patients and a challenge for their physician. Chronic pain often arises from multiple tissue sources and involves multiple chemical mediators and pain transmission pathways. Successful long-term pain management requires analgesic regimens that can treat pains of multiple origin and type. Safety and tolerability are also a high priority when prescribing chronic therapy. Recent publications and regulatory developments affecting anti-inflammatory drugs have limited the options available for the management of chronic pain. Major concerns in long-term use of anti-inflammatory drugs include renal toxicity, gastrointestinal ulceration and bleeding and cardiovascular events, which can be of particular concern for elderly patients. Opioid agents avoid the end-organ toxicity seen with anti-inflammatory drugs, but their use may be limited, especially in the long term, by side effects such as constipation or sedation and by concerns about the potential for physical or psychological dependence. Paracetamol (acetaminophen) has a favourable safety and tolerability profile, although exceeding the recommended dose (up to 4 g/day) carries a risk of liver damage. It exerts simultaneous anti-nociception at both spinal and supra-spinal sites, and has shown self-synergy between these two routes of activity. Tramadol, an atypical weak opioid with a multi-modal mechanism of action, inhibits re-uptake of multiple neurotransmitters and has an improved safety and tolerability profile compared with traditional opioids. Rational combinations of analgesic drugs offer a viable approach to managing persistent pain that involves multiple sites or pathways. The combination of paracetamol plus tramadol brings together two well-known analgesics that have different but complementary mechanisms of analgesic action. Laboratory studies have demonstrated that these agents interact to produce synergistic analgesia with a desirable safety/efficacy profile.

Chemically Induced Seizures

Drug- and toxin-associated seizures (DTS) may result from exposure to a wide variety of agents. Most DTS can be managed with supportive care. First-line anticonvulsant therapy should include benzodiazepines, unless agents require a specific antidote. Phenytoin is generally not expected to be useful for DTS and in some instances may be harmful. In this article the authors discuss the pathophysiology of DTS, the potential differential diagnosis, and the clinical presentation. They also review selected agents that cause DTS and provide an overview of how the clinician should approach the management of patients who have DTS.

Drug- and toxin-associated seizures

Drug- and toxin-associated seizures may result from exposure to a wide variety of agents. Obtaining a comprehensive history behind the exposure is generally more helpful than diagnostic testing. Most DTS may be managed with supportive care, including benzodiazepines, except in the case of agents that require a specific intervention or antidote.

Co-proxamol and suicide: preventing the continuing toll of overdose deaths

Restricting means for suicide is a key element in suicide prevention strategies of all countries where these have been introduced. Preventing deaths from analgesic overdoses is highlighted in the National Suicide Prevention Strategy for England. The problem of self-poisoning with the prescription-only drug co-proxamol (dextropropoxyphene plus paracetamol) has received attention in several countries. We have conducted a review of the international literature related to possible strategies to tackle this problem. In England and Wales in 1997-1999, 18% of drug-related suicides involved co-proxamol; these constituted 5% of all suicides. Death usually results from the toxic effects of dextropropoxyphene on respiration or cardiac function. Death from co-proxamol overdose may occur rapidly, the lethal dose can be relatively low, and the effects are potentiated by alcohol and other CNS depressants. The majority of co-proxamol overdose deaths occur before hospital treatment can be received. The risk can extend to others in the household of the person for whom the drug is prescribed. While there is limited evidence that educational strategies have been effective in reducing deaths from co-proxamol poisoning, initiatives in Scandinavia, Australia and the UK to restrict availability of co-proxamol have produced promising results. Given the paucity of evidence for superior therapeutic efficacy of co-proxamol over other less toxic analgesics, there are good reasons to question whether it should continue to be prescribed.

Membrane toxicity of opioids measured by protozoan motility

The acute toxicity of some opioid drugs cannot solely be explained by a specific interaction with the opioid receptor. The anaesthetic-like membrane effect of 10 opioid agents and the antagonist naloxone was determined and correlated with their hydrophobicity. The inhibitory effect of drugs on protozoan motility was used as a measure of their membrane toxicity, measured by the reduction in swimming speed of Tetrahymena pyriformis using an image analysis system. Hydrophobicity was determined as the n-octanol/water partition coefficient, at pH 7.4, 37 degrees C. Opioid agents dose-dependently reduced the swimming speed of Tetrahymena pyriformis with a wide range of IC50 values. Some weak opioid agents were shown to have high protozoan immobilising potency comparable to quinidine, an agent with known membrane stabilising activity. Norpropoxyphene, the metabolite of dextropropoxyphene, with little affinity for the opioid receptor, also had a high potency. The inhibition of protozoan motility by these opioid agents was not antagonised by the opioid receptor antagonist naloxone; moreover an additive inhibitory action was demonstrated when opioid agents were combined with naloxone. The effect of opioid agents on protozoan motility was closely correlated with their partition coefficient but not with their known affinity for opioid receptors. These results suggest that opioid agents possess differing degrees of membrane depressant action independent from their interaction with the opioid receptor, and have a potential for causing depressant effects on excitable tissues.

Adverse cardiac manifestations following dextropropoxyphene overdose: can naloxone be helpful?

Dextropropoxyphene overdose may be complicated by serious cardiovascular manifestations, including conduction abnormalities and collapse. We report two patients in whom cardiac toxicity developed. Cardiovascular depression seemed to be improved after naloxone infusion in these two cases. Possible mechanisms are briefly discussed.

Propoxyphene-induced wide QRS complex dysrhythmia responsive to sodium bicarbonate--a case report

Propoxyphene overdose is known to cause widening of the QRS complex on ECG. We report a case of a 54-year-old female who ingested approximately 100 propoxyphene hydrochloride tablets in a suicide attempt. She developed a wide complex dysrhythmia which responded to sodium bicarbonate therapy. Propoxyphene-induced wide complex dysrhythmia responsive to sodium bicarbonate therapy has not been previously reported in the literature.

Oral narcotic analgesics. Choosing the most appropriate agent for acute pain

Narcotic analgesics are the most effective oral agents available for treatment of acute pain. A familiarity with the salient characteristics of the various agents enables physicians to choose the most effective one for use in the outpatient setting.

Dopamine and dobutamine reduce myocardial d-propoxyphene content in experimentally intoxicated rats

The effect of sympathomimetic intervention with dopamine or dobutamine on the myocardial uptake of d-propoxyphene was investigated experimentally in rats. The d-propoxyphene (19 mg kg-1 h-1) was continuously infused, intravenously, over 45 min. After 20 min of infusion the rats were given either dopamine (12.5 micrograms kg-1 min-1 or 25 micrograms kg-1 min-1), dobutamine (25 micrograms kg-1 min-1 or 45 micrograms kg-1 min-1) or normal saline (control). Each group consisted of eight rats. The myocardial d-propoxyphene content was significantly lower in the two groups given dopamine and in the group given dobutamine 45 micrograms kg-1 min-1 than in the control group (P less than 0.05). This finding indicates the benefit of early sympathomimetic intervention with either dopamine or dobutamine in d-propoxyphene intoxication.

Marked QRS complex abnormalities and sodium channel blockade by propoxyphene reversed with lidocaine

The opiate analgesic propoxyphene produces cardiac toxicity when taken in overdose. We recently observed a patient with propoxyphene overdose in whom marked QRS widening was reversed by lidocaine. The reversal is apparently paradoxical as both agents block the inward sodium current (INa). We examined possible mechanisms of the reversal by measuring INa in rabbit atrial myocytes during exposure to propoxyphene and the combination of propoxyphene and lidocaine (60 and 80 microM, respectively). Propoxyphene caused use-dependent block of INa during pulse train stimulation. Block recovered slowly with time constants of 20.8 +/- 3.9 s. Block during lidocaine exposure recovered with time constants of 2-3 s. During exposure to the mixture, block recovered as a double exponential. The half time for recovery during exposure to the mixture was 1.6 +/- .9 s compared with a half-time of 14.3 +/- 2.9 s during exposure to propoxyphene alone. During pulse train stimulation, less steady-state block was observed during exposure to the mixture than during exposure to propoxyphene alone when the interval between pulses was greater than 0.95 s. Both drugs compete for a common receptor during the polarizing phase. The more rapid dissociation of lidocaine during the recovery period leads to less block during the mixture than during exposure to propoxyphene alone. The experiments suggest a mechanism for reversal of the cardiac toxicity of drugs which have slow unbinding kinetics.

Cardiovascular function measured by ultrasound Doppler in healthy young men after ingestion of dextropropoxyphene napsylat

In a double blind cross-over study 10 healthy male volunteers were given either 300 mg dextropropoxyphene napsylat (DP) or placebo daily for 16 days. The serum levels of DP and the metabolite nordextropropoxyphene were measured on day 3, 6 and 16. Haemodynamic measurements were made on day 1 and day 16, both at rest and during exercise. The measurements were made non-invasively, with a pulsed ultrasound Doppler. Blood pressure, heart rate, velocity, cardiac output, left cardiac work, increased during work, but showing no significant differences between the groups. The systolic time intervals were also measured by the ultrasound Doppler. The preejection period increased significantly in the DP-group, whereas the ratio preejection period/left ventricular ejection time which reflects the contractility of the heart did not differ significantly. It is concluded that DP taken daily in a normal dose for 16 days did not affect the heart function in healthy young men.

Physical assessment and differential diagnosis of the poisoned patient

The rapid diagnosis and immediate intervention required in patients with serious drug overdose or poisoning makes toxicological screening of limited value to the emergency department physician. Instead, a careful clinical evaluation using the history, physical examination, and the more readily available laboratory tests may allow a tentative diagnosis and the initiation of life-saving treatment. Laboratory tests should include serum osmolality, electrolytes, glucose, BUN and an estimation of the anion and osmolar gaps. The ECG can also provide useful information. Clinical findings of important include altered blood pressure, pulse, respiration and body temperature, the presence of coma, agitation, delirium or psychosis, and muscular weakness. An ophthalmological examination is also of importance in the acutely poisoned patient. Oral burns or dysphagia may occur following ingestion of any strongly reactive substance, but the absence of oral burns does not preclude the possibility of oesophageal or stomach injury. Odours and skin colour may also contribute to the diagnosis. Comprehensive toxicology screening may not be immediately available, or may be inaccurate, thus adding little to the information obtained during the initial evaluation of the poisoned patient.

Effects of prenalterol on central hemodynamics and myocardial metabolism in experimental propoxyphene-induced shock

The hemodynamic and cardiometabolic effects of prenalterol were evaluated in propoxyphene-induced circulatory shock in 10 pentobarbital-anesthetized pigs. Circulatory shock (i.e. a systolic arterial blood pressure below 60 mmHg (8 kPa) and/or a cardiac index of less than 2.0 1 X min-1 X m-2) was induced by intravenous propoxyphene chloride 15 mg X min-1. Circulatory shock occurred after 26 +/- 3 mg X kg-1 of propoxyphene. During continuous infusion of propoxyphene, consecutive doses of prenalterol 0.5, 1.0, 2.0 and 4.0 mg i.v. were injected with an interval between increments of 8 min. The maximum effect of prenalterol was seen following the 2 mg dose. Increases were observed in mean arterial blood pressure, cardiac index, stroke volume index, left ventricular stroke work index, right ventricular stroke work index, maximum rate of rise of ventricular pressure, and total body oxygen consumption. Decreases were observed in pulmonary artery occlusion pressure, mean right atrial pressure and systemic vascular resistance, whereas heart rate and pulmonary vascular resistance remained unchanged. The cardiometabolic parameters: coronary sinus flow, coronary vascular resistance, myocardial oxygen consumption and extraction, remained low. Due to profound vasodilation, normal perfusion pressures were not reestablished. In conclusion, prenalterol improved cardiac performance by a significant positive inotropic action. However, pure inotropic stimulation was not sufficient to counteract the circulatory shock state during severe propoxyphene intoxication.

Severe acute propoxyphene overdose: plasma concentrations of propoxyphene and norpropoxyphene and the effect of dopamine on circulatory failure

Twelve patients with cardiovascular failure because of propoxyphene self-poisoning were treated with dopamine. The patients responded favourably to dopamine infusion (2-17 micrograms/kg/min) with a dose-dependent rise in systolic arterial blood pressure and a fall in central venous pressure and copious urinary output. Side effects during infusion were few, and in periods where dopamine infusion exceeded 10 micrograms/kg/min no tachyarrhythmias were seen. Eleven of the patients were treated on a respirator. Two patients were discharged from the ICU with signs of hypoxic brain damage, one of whom recovered completely after 2 weeks. Serum propoxyphene and norpropoxyphene were measured in nine patients. All but one patient had either propoxyphene or norpropoxyphene concentrations above 3 mumol/l.

Self-poisoning treated in an ICU: drug pattern, acute mortality and short-term survival

A total of 1558 admissions to an ICU over 5 years because of severe self-poisoning with drugs provides the basis for this study. Three drugs accounted for 60% of the admissions: overdose with barbiturates in 28%, with tricyclic antidepressants in 19% and with propoxyphene in 14%. The annual incidence of poisonings with barbiturates and tricyclic antidepressants was the same during the period, whereas the incidence of propoxyphene intoxication increased by 80%. Intensive supportive care was the main principle of treatment. All patients were artificially ventilated. The mortality rate was 6.1%, salicylate, propoxyphene and strong analgesics having the highest mortalities (11%, 9% and 9%, respectively). A mortality rate of 3% was found following overdose with tricyclic antidepressants. By 36 months after the overdose, 235 patients (18%) had died. The expected number of deaths was 39 (3%). The suicide rate in the follow-up period was 10%, in the majority (75%) of whom death was caused by a new episode of self-poisoning.

The effects of naloxone on central hemodynamics and myocardial metabolism in experimental propoxyphene-induced circulatory shock

The courses of the hemodynamic and cardiometabolic effects of naloxone were evaluated in propoxyphene-induced shock in eight pentobarbital-anesthetized pigs. Circulatory shock was induced by an infusion of propoxyphene chloride 15 mg . min-1 i.v. At shock, i.e. MAP less than 60 mmHg and/or CI less than 2.0 l . min-1 . m-2, naloxone was administered at 0.75, 1.5 and 3.0 mg . kg-1 with an interval between increments of 8 min. The propoxyphene infusion of 15 mg . min-1 was continued throughout the study. Following the injection of naloxone 0.75 mg . kg-1, increases were observed (% of baseline value) in MAP (41%), i.e. deficit to baseline 59%, HR (66%), CI (67%) and SVI (108%), whereas MPAP and MPAOP were unchanged. dP/dt increased (34%). In the coronary circulation naloxone initiated the following changes: CSF increased (69%) as did MVO2 (48%) with unchanged MO2-extraction, but CVR decreased further (36%). The maximum effects of naloxone were registered 2-3 min after 0.75 mg . kg-1. Following 1.5 and 3.0 mg . kg-1, no changes in hemodynamics were observed other than those caused by progressing propoxyphene intoxication.

The effects of cardiac pacing on central hemodynamics in experimental propoxyphene-induced cardiac failure

Coronary sinus pacing was evaluated in 10 pigs during propoxyphene-induced cardiac failure. From baseline, propoxyphene chloride 15 mg . min-1 was infused until circulatory shock developed. Cardiac pacing was evaluated at different dose levels expressed as % of the shock dose of propoxyphene: at intoxication levels below 50% of the shock dose, cardiac pacing improved cardiac performance. At dose levels above 50% of the shock dose cardiac performance deteriorated further during pacing. The results are consistent with a severe negative inotropic effect of propoxyphene in overdose.

The effects of dopamine on central hemodynamics and myocardial metabolism in experimental propoxyphene-induced shock

The hemodynamic and cardiometabolic effects of dopamine were evaluated in propoxyphene-induced circulatory shock in eight pentobarbital anesthetized pigs. Circulatory shock was induced by an infusion of propoxyphene chloride 15 mg . min-1 i.v. At shock, i.e. CI less than or equal to 2.0 l . min-1 . m-2 and/or MAP less than or equal to 60 mmHg, dopamine was infused at 10, 20, 40, 80 and 160 micrograms . kg-1 . min-1 with an interval between increments of 8 min. After 30 min at 160 micrograms . kg-1 . min-1, the infusion rate was reversibly decreased. The propoxyphene infusion of 15 mg . min-1 was continued throughout the study. Dopamine improved the circulation in seven animals; one animal died in refractory shock during dopamine infusion. Dopamine infusion at shock level resulted in an increase of the following variables (% of baseline value): MAP (69%), HR (109%), CI (138%) and SVI (129%). Normalisation was seen in MRAP (120%) and in MPAOP (100%). A profound decrease in systemic vascular resistance was unchanged. Increases were seen in left and right ventricular stroke work index, to 88% and 176% of baseline, respectively. Left ventricular dP/dt increased (170%). In the coronary circulation myocardial blood flow increased (133%) as did myocardial oxygen consumption (65%) concomitant with a decrease in myocardial oxygen uptake (41%), but coronary vascular resistance progressively decreased (38%). The myocardial propoxyphene extraction changed from +54% to -86% during peak dopamine infusion. In conclusion, dopamine reversed cardiac failure in propoxyphene overdose by a marked positive inotropic stimulation restoring contractility. A marked positive chronotropic stimulation maintained a sufficient cardiac index and a normal blood pressure in spite of a profound vasodilatation which was unresponsive to dopamine.

Severe, acute propoxyphene overdose treated with dopamine

Six patients suffering from cardiovascular failure due to acute propoxyphene overdose, were treated with dopamine infusion in doses of 2-17 microgram/kg/min. All patients responded with increased systolic arterial blood pressure, increased urinary output and decreased central venous pressure. The two most severely poisoned patients showed no increase in heart rate in spite of dopamine infusion in positively chronotropic doses. In two out of three patients the initially abnormal ECGs normalised during treatment. It is concluded that dopamine seems suitable for reversal of propoxyphene induced circulatory failure.

Cardiac pacing and central hemodynamics in experimental propoxyphene induced shock

Coronary sinus pacing was evaluated in 10 pigs with propoxyphene induced cardiac failure. During the early phase of intoxication cardiac pacing improved cardiac function slightly but significantly worsened it in severely intoxicated animals. The results are consistent with marked negative inotropic action of propoxyphene in overdose.

Acute self-poisoning with tricyclic antidepressants in 295 consecutive patients treated in an ICU

Clinical findings on admission to hospital and outcome in 295 consecutive patients with severe tricyclic antidepressant self-poisoning treated in an ICU are presented. Cerebral depression was observed in 92%, convulsions in 23% and respiratory failure was present in 72%. Cardiovascular function was impaired in 44% and an abnormal ECG was found in 57%. Cardiac arrest was treated in 14 patients (6%) of whom seven were resuscitated. The mortality rate was 2%. All patients were artificially ventilated. A beneficial effect of respiratory alkalosis on cardiac arrhythmias is supported.