Mechanism of respiratory insufficiency in pure or mixed drug-induced coma involving benzodiazepines

Misdiagnosis of prolonged psychogenic non-epileptic seizures as status epilepticus: epidemiology and associated risks

OBJECTIVE

To determine the epidemiology of prolonged psychogenic non-epileptic seizures (pPNES) misdiagnosed as status epilepticus, as well as the risks associated with non-indicated treatment.

METHODS

We performed an individual patient data analysis from the Rapid Anticonvulsant Medication Prior to Arrival Trial (RAMPART) and the Established Status Epilepticus Treatment Trial (ESETT) to assess incidence, patient characteristics and clinical course of misdiagnosed pPNES.

RESULTS

Among 980 patients aged 8 years or older diagnosed and treated for status epilepticus in RAMPART and ESETT, 79 (8.1%) were discharged with a final diagnosis of pPNES. The relative incidence was highest in adolescents and young adults (20.1%). The typical female preponderance seen in that age bracket was not evident in children and older adults. Adverse effects, including respiratory depression and intubation, were documented in 26% of patients with pPNES receiving benzodiazepines in RAMPART and 33% of patients receiving additional second-line medication in ESETT. In ESETT, patients who were treated with benzodiazepines before hospital admission had higher rates of unresponsiveness and severe adverse effects than those treated after admission, suggesting cumulative effects of accelerated treatment momentum. Across trials, one in five patients with pPNES were admitted to an intensive care unit.

CONCLUSIONS

Misdiagnosis and treatment of pPNES as status epilepticus are a common and widespread problem with deleterious consequences. Mitigating it will require training of emergency staff in semiological diagnosis. Status epilepticus response protocols should incorporate appropriate diagnostic re-evaluations at each step of treatment escalation, especially in clinical trials.

Mortality and concurrent use of opioids and hypnotics in older patients: A retrospective cohort study

BACKGROUND

Benzodiazepine hypnotics and the related nonbenzodiazepine hypnotics (z-drugs) are among the most frequently prescribed medications for older adults. Both can depress respiration, which could have fatal cardiorespiratory effects, particularly among patients with concurrent opioid use. Trazodone, frequently prescribed in low doses for insomnia, has minimal respiratory effects, and, consequently, may be a safer hypnotic for older patients. Thus, for patients beginning treatment with benzodiazepine hypnotics or z-drugs, we compared deaths during periods of current hypnotic use, without or with concurrent opioids, to those for comparable patients receiving trazodone in doses up to 100 mg.

METHODS AND FINDINGS

The retrospective cohort study in the United States included 400,924 Medicare beneficiaries 65 years of age or older without severe illness or evidence of substance use disorder initiating study hypnotic therapy from January 2014 through September 2015. Study endpoints were out-of-hospital (primary) and total mortality. Hazard ratios (HRs) were adjusted for demographic characteristics, psychiatric and neurologic disorders, cardiovascular and renal conditions, respiratory diseases, pain-related diagnoses and medications, measures of frailty, and medical care utilization in a time-dependent propensity score-stratified analysis. Patients without concurrent opioids had 32,388 person-years of current use, 260 (8.0/1,000 person-years) out-of-hospital and 418 (12.9/1,000) total deaths for benzodiazepines; 26,497 person-years,150 (5.7/1,000) out-of-hospital and 227 (8.6/1,000) total deaths for z-drugs; and 16,177 person-years,156 (9.6/1,000) out-of-hospital and 256 (15.8/1,000) total deaths for trazodone. Out-of-hospital and total mortality for benzodiazepines (respective HRs: 0.99 [95% confidence interval, 0.81 to 1.22, p = 0.954] and 0.95 [0.82 to 1.14, p = 0.513] and z-drugs (HRs: 0.96 [0.76 to 1.23], p = 0.767 and 0.87 [0.72 to 1.05], p = 0.153) did not differ significantly from that for trazodone. Patients with concurrent opioids had 4,278 person-years of current use, 90 (21.0/1,000) out-of-hospital and 127 (29.7/1,000) total deaths for benzodiazepines; 3,541 person-years, 40 (11.3/1,000) out-of-hospital and 64 (18.1/1,000) total deaths for z-drugs; and 2,347 person-years, 19 (8.1/1,000) out-of-hospital and 36 (15.3/1,000) total deaths for trazodone. Out-of-hospital and total mortality for benzodiazepines (HRs: 3.02 [1.83 to 4.97], p < 0.001 and 2.21 [1.52 to 3.20], p < 0.001) and z-drugs (HRs: 1.98 [1.14 to 3.44], p = 0.015 and 1.65 [1.09 to 2.49], p = 0.018) were significantly increased relative to trazodone; findings were similar with exclusion of overdose deaths or restriction to those with cardiovascular causes. Limitations included composition of the study cohort and potential confounding by unmeasured variables.

CONCLUSIONS

In US Medicare beneficiaries 65 years of age or older without concurrent opioids who initiated treatment with benzodiazepine hypnotics, z-drugs, or low-dose trazodone, study hypnotics were not associated with mortality. With concurrent opioids, benzodiazepines and z-drugs were associated with increased out-of-hospital and total mortality. These findings indicate that the dangers of benzodiazepine-opioid coadministration go beyond the documented association with overdose death and suggest that in combination with opioids, the z-drugs may be more hazardous than previously thought.

Mortality and use of psychotropic medication in patients with stroke: a population-wide, register-based study

OBJECTIVES

The study sought to describe whether psychotropic medication may have long-term side effects in patients with stroke compared with controls.

SETTING

Use of national register data from healthcare services were identified from the Danish National Patient Registry in Denmark. Information about psychotropic medication use was obtained from the Danish Register of Medicinal Product Statistics.

OBJECTIVES

We aimed to evaluate all-cause mortality in relation to the use of benzodiazepines, antidepressants and antipsychotics in patients with stroke and matched controls.

PARTICIPANTS

Patients with a diagnosis of stroke and either no drug use or preindex use of psychotropic medication (n=49,968) and compared with control subjects (n=86,100) matched on age, gender, marital status and community location.

PRIMARY OUTCOME MEASURE

All-cause mortality.

RESULTS

All-cause mortality was higher in patients with previous stroke compared with control subjects. Mortality HRs were increased for participants prescribed serotonergic antidepressant drugs (HR=1.699 (SD=0.030), p=0.001 in patients; HR=1.908 (0.022), p<0.001 in controls, respectively), tricyclic antidepressants (HR=1.365 (0.045), p<0.001; HR=1.733 (0.022), p<0.001), benzodiazepines (HR=1.643 (0.040), p<0.001; HR=1.776 (0.053), p<0.001), benzodiazepine-like drugs (HR=1.776 (0.021), p<0.001; HR=1.547 (0.025), p<0.001), first-generation antipsychotics (HR=2.001 (0.076), p<0.001; HR=3.361 (0.159), p<0.001) and second-generation antipsychotics (HR=1.645 (0.070), p<0.001; HR=2.555 (0.086), p<0.001), compared with no drug use. Interaction analysis suggested statistically significantly higher mortality HRs for most classes of psychotropic drugs in controls compared with patients with stroke.

CONCLUSIONS

All-cause mortality was higher in patients with stroke and controls treated with benzodiazepines, antidepressants and antipsychotics than in their untreated counterparts. Our findings suggest that care should be taken in the use and prescription of such drugs, and that they should be used in conjunction with adequate clinical controls.

Flumazenil, naloxone and the 'coma cocktail'

Flumazenil and naloxone are considered to be pharmacologically ideal antidotes. By competitive binding at the molecular target receptors, they are highly specific antagonists of two important drug classes, the benzodiazepines and opioids, respectively. Both antidotes enjoy rapid onset and short duration after parenteral administration, are easily titrated and are essentially devoid of agonist effects. Yet only naloxone is widely used as a component of the 'coma cocktail', a sequence of empirical treatments to correct altered mental status, while experts discourage the use of flumazenil for such patients. This review contrasts the history, indications, published evidence and novel applications for each antidote in order to explain this disparity in the clinical use of these 'ideal' antidotes.

Noninvasive End Tidal CO2 Is Unhelpful in the Prediction of Complications in Deliberate Drug Poisoning

STUDY OBJECTIVE

We study the performance of capnometry in the detection of early complications after deliberate drug poisoning.

METHODS

This was a prospective cohort study of self-poisoned adult patients who presented at an emergency department (ED) between April 20, 2012, and May 6, 2014. Patients who ingested at least 1 neurologic or respiratory depressant drug were included. The primary outcome was the predictive value of an end tidal CO2 (etco2) measurement greater than or equal to 50 mm Hg for the detection of early complications defined a priori by hypoxia requiring oxygen greater than or equal to 3 L/min, bradypnea less than or equal to 10 breaths/min, or ICU admission after intubation or antidote administration because of unresponsiveness to pain or respiratory arrest. Consciousness scales and clinical data were recorded at admission and every 30 minutes. Noninvasive etco2 was continuously measured for 2 hours after inclusion unless the patient was admitted to the ICU. Patients and physicians were blinded to etco2 values.

RESULTS

Two hundred one patients were included, 35 of whom exhibited at least 1 complication. An etco2 measurement greater than or equal to 50 mm Hg predicted the onset of a complication, with a sensitivity of 46% (95% confidence interval [CI] 29% to 63%) and a specificity of 80% (95% CI 73% to 86%), leading to a positive predictive value of 33% (95% CI 20% to 48%) and a negative predictive value of 88% (95% CI 81% to 92%). etco2 was less able to predict complications than the Glasgow Coma Scale score at inclusion.

CONCLUSION

Capnometry in isolation does not provide adequate prediction of early complications in self-poisoned patients referred to the ED. A dynamic minute-by-minute assessment of etco2 could be more predictive.

Increased all-cause mortality with use of psychotropic medication in dementia patients and controls: A population-based register study

We aimed to evaluate all-cause mortality of middle-aged and elderly subjects diagnosed with dementia and treated with psychotropic drugs as compared with controls subjects. Using data from the Danish National Patient Registry, n=26,821 adults with a diagnosis of dementia were included. They were compared with 44,286 control subjects with a minimum follow-up of four years and matched on age, gender, marital status, and community location. Information about psychotropic medication use (benzodiazepines, antidepressants, antipsychotics) was obtained from the Danish Medicinal Product Statistics. All-cause mortality was higher in patients with dementia as compared to control subjects. Mortality hazard ratios were increased for subjects prescribed serotonergic antidepressant drugs (respectively, HR=1.355 (SD=0.023), P=0.001 in patients; HR=1.808 (0.033), P<0.001 in controls), tricyclic antidepressants (HR=1.004 (0.046), P=0.925; HR=1.406 (0.061), P<0.001), benzodiazepines (HR=1.131 (0.039), P=0.060); HR=1.362 (0.028), P<0.001), benzodiazepine-like drugs (HR=1.108 (0.031), P=0.078; HR=1.564 (0.037, P<0.001), first-generation antipsychotics (HR=1.183 (0.074), P=0.022; HR=2.026 (0.114), P<0.001), and second-generation antipsychotics (HR=1.380 (0.042), P<0.001; HR=1.785 (0.088), P<0.001), as compared with no drug use. Interaction analysis suggested statistically significantly higher mortality hazard ratios for most classes of psychotropic drugs in controls than in dementia patients. We found that use of psychotropic drugs is associated with increased all-cause mortality in both patients with dementia and control subjects. Thus, the frequently reported increased mortality with antipsychotic drugs in dementia is not restricted to subjects with impaired cognition and is not restricted to only one class of psychotropic drugs.

The Large Role of Prescription Drugs in Accidental Drug Deaths

Drug abuse may involve illicit drugs, prescription drugs, or the combination of illicit and prescription drugs, with or without the use of alcohol. Historically, illicit drugs have been responsible for many of the drug-related deaths investigated by medical examiner and coroner offices. However, in more recent years, deaths resulting from prescription drugs have become increasingly more common. This study reviewed all accidental (unintentional) drug deaths that were investigated at a medical examiner's office over a one-year time frame. The study revealed that prescription drugs made up the largest category of drug deaths, followed by prescription drug/illicit drug combinations, followed by illicit drugs. Drugs capable of causing or contributing to significant respiratory insufficiency such as opioids, benzodiazepines, relaxants (defined as muscle relaxants or sleep medications), and alcohol, or some combination thereof, were detected in 197 out of 256 (77%) of all accidental drug deaths, and were detected in 132 out of 138 (95%) of all prescription drug deaths (cases without any illicit drugs detected). These prescription drugs were most often found in combination, and their similar respiratory depressant effects can be cumulative and deadly.

A sound sleep

Benzodiazepine is a commonly encountered agent of poisoning, which is readily diagnosed by a pertinent history of drug ingestion and the clinical scenario. In the absence of a proper drug history, the diagnosis becomes challenging. Proper clinical assessment, urine assays and imaging play a very important role in reaching the diagnosis. We present a case of acute benzodiazepine poisoning without a history of drug intake. The key pointers toward diagnosis were an unarousable state with obstructive apnea. Magnetic resonance imaging (MRI) of the brain revealed peculiar symmetrical isolated globus pallidus T2 hyperintensity. We believe this to be the first report of isolated bilateral basal ganglia T2-weighted hyperintensity in MRI in the setting of acute benzodiazepine poisoning from India.

Prospective comparative assessment of buprenorphine overdose with heroin and methadone: clinical characteristics and response to antidotal treatment

Buprenorphine is a partial opioid agonist with a "ceiling effect" for respiratory depression. Despite this, it has been associated with severe overdoses. Conflicting data exist regarding its response in overdose to naloxone. We compared clinical overdose characteristics of buprenorphine with heroin and methadone and assessed responses to naloxone and flumazenil. Patients admitted to two intensive care units with severe opioid overdoses were enrolled into this 4-year prospective study. Urine and blood toxicological screening were performed to identify overdoses involving predominantly buprenorphine, heroin, or methadone. Eighty-four patients with heroin (n = 26), buprenorphine (n = 39), or methadone (n = 19) overdoses were analyzed. In the buprenorphine group, sedative drug coingestions were frequent (95%), whereas in the methadone group, suicide attempts were significantly more often reported (p = .0007). Buprenorphine overdose induced an opioid syndrome not differing significantly from heroin and methadone in mental status (as measured by Glasgow Coma Score) or arterial blood gases. Mental status depression was not reversed in buprenorphine overdoses with naloxone (0.4-0.8 mg) but did improve with flumazenil (0.2-1 mg) if benzodiazepines were coingested. In conclusion, buprenorphine overdose causes an opioid syndrome clinically indistinguishable from heroin and methadone. Although mental status and respiratory depression are often unresponsive to low-dose naloxone, flumazenil may be effective in buprenorphine overdoses involving benzodiazepines.

Sustained preinspiratory cortical potentials during prolonged inspiratory threshold loading in humans

Humans can program and control movements, including breathing-related movements. On the electroencephalogram (EEG), this preparation is accompanied by a low-amplitude negativity starting approximately 2.5 s before inspiration that is best known as a Bereitschaftspotential (BP). The presence of BPs has been described during the compensation of mechanical inspiratory loading, thus identifying a cortical involvement in the corresponding ventilatory behavior. The pathophysiological interpretation of this cortical involvement depends on its transient or enduring nature. This study addressed this issue by looking for BPs during sustained inspiratory loading (1 h). Nine healthy male volunteers were studied during unloaded quiet breathing and inspiratory threshold loading (with unloaded expiration). Analyses of EEG signal and ventilatory variables were used to compare beginning and end of sessions. Inspiratory threshold loading caused ventilatory modifications that persisted, unchanged, for an hour. The presence of a BP at the beginning and end of a session was the most frequent occurrence (6 of 9 cases with a 17-cmH2O threshold load; 8 of 9 cases with a 23-cmH2O load). These observations support the hypothesis that the cerebral cortex is involved in the compensation of sustained experimental inspiratory loading. How this translates to respiratory disease involving acute changes in respiratory mechanics remains to be determined.

[Mechanisms of opioid-induced overdose: experimental approach to clinical concerns]

The widely used term "overdose" denotes a toxic effect: opioid-induced intoxication and a mechanism: the poisoning results only from an overdose. Surprisingly, our understanding of the pathophysiology of this deadly complication is limited. In drug users, we attempted to: (1) improve knowledge of drug-induced respiratory effects; (2) clarify the mechanisms of drug interactions; (3) identify factors of variability and vulnerability. A prospective study of opioid overdoses confirmed that poisonings involving buprenorphine do exist. However, the mechanisms of buprenorphine poisoning are more complex than only an overdose, particularly the severity is less than that induced by heroin. In contrast, methadone overdose is life-threatening. Experimental studies addressed several clinical questions and also showed limited discrepancies. At pharmacological doses, opioids decrease the ventilatory response to CO(2). However, this effect does not account for the morbimortality of opioid poisonings. The mechanisms of opioid-induced morbimortality are different. Buprenorphine at doses near its median lethal dose did not induce acute respiratory failure as defined by a decrease in the partial pressure of oxygen in arterial blood (PaO(2)). In contrast, the combination of buprenorphine with flunitrazepam results in a decrease in PaO(2). This harmful interaction does not exist with other benzodiazepines in the rat, except for very high doses of nordazepam. The interaction results from a pharmacokinetic process. In contrast, methadone causes a dose-dependent decrease in PaO(2,) even significant before hypercapnia. We are assessing the relationships between on one hand alterations of ventilatory pattern and of arterial blood gas and on the other hand the different types of opiate receptors in the rats.

Does high-dose buprenorphine cause respiratory depression?: possible mechanisms and therapeutic consequences

Buprenorphine is an opioid agonist-antagonist with a 'ceiling effect' for respiratory depression. Compared with methadone, its unique pharmacology offers practical advantages and enhanced safety when prescribed as recommended and supervised by a physician. Buprenorphine has been approved in several countries as an efficient and safe maintenance therapy for heroin addiction. Its use resulted in a salutary effect with a reduction in heroin overdose-related deaths in countries that implemented office-based buprenorphine maintenance. In France, however, where high-dose buprenorphine has been marketed since 1996, several cases of asphyxic deaths were reported among addicts treated with buprenorphine. Death resulted from buprenorphine intravenous misuse or concomitant sedative drug ingestion, such as benzodiazepines. In these situations of abuse, misuse, or in association with elevated doses of psychotropic drugs, buprenorphine may cause severe respiratory depression. Unlike other opiates, the respiratory effects from buprenorphine are not responsive to naloxone. However, the exact mechanism of buprenorphine-induced effects on ventilation is still unknown. The role of norbuprenorphine, the main N-dealkylated buprenorphine metabolite with potent respiratory depressor activity, also remains unclear. Experimental studies investigating the respiratory effects of combinations of high doses of buprenorphine and benzodiazepines suggested that this drug-drug interaction may result from a pharmacodynamic interaction. A pharmacokinetic interaction between buprenorphine and flunitrazepam is also considered. As there are many questions regarding the possible dangers of death or respiratory depression associated with buprenorphine use, we aimed to present a comprehensive critical review of the published clinical and experimental studies on buprenorphine respiratory effects.

Cerebral and plasma kinetics of a high dose of midazolam and correlations with its respiratory effects in rats

Benzodiazepine poisoning causes coma and respiratory depression. Our objective was to determine whether, and to what extent, arterial blood gas disturbances correlated with blood or cerebral kinetics of midazolam. A 160 mgkg(-1) single dose of midazolam was infused intravenously over 20 min in catheterized male Sprague-Dawley rats. Midazolam kinetics was simultaneously determined in plasma and brain using striatal microdialysis. Midazolam concentrations were measured using a high-performance liquid chromatographic assay with ultraviolet detection. Midazolam (160 mgkg(-1)) reproducibly induced deep coma with respiratory acidosis. Plasma midazolam kinetics was well described by a bi-exponential model, with an elimination half-life of 6.4+/-1.8 h. The striatal dialysate concentration peaked at 50.0+/-8.9 min after the end of infusion, with a significant delay to peak concentration compared to plasma. Respiratory depression, assessed by the elevation in PaCO2, was more closely correlated with midazolam striatal dialysate rather than plasma kinetics. These results suggest a central mechanism for midazolam respiratory effects at toxic doses in rats. In conclusion, our study showed a delayed onset in peak PaCO2 and pH effects after the slow infusion of a toxic dose of midazolam in rats. The effects on arterial blood gases were better correlated with midazolam striatal concentrations than with plasma concentrations. This study may contribute to better understanding of benzodiazepine-induced respiratory depression in poisonings.

The effect of buprenorphine and benzodiazepines on respiration in the rat

Methadone and buprenorphine are the two main opioid substitution treatments for heroin dependence currently offered in Australia. A number of publications have implicated buprenorphine as being potentially dangerous in combination with benzodiazepines but no comparison has been made to the relative dangers of benzodiazepines combined with buprenorphine or methadone. The effect of i.v. methadone and buprenorphine on respiration was investigated by evaluating arterial blood pCO2, pO2 and pH, and measuring respiratory rate in rats. Measurements were taken at 0, 15, 30, 60, 120, 180 and 240 min after i.v. administration of methadone or buprenorphine. Effects on respiration were greatest 15 min after i.v. drug administration. The effect of methadone and buprenorphine on respiration was compared with and without diazepam pretreatment (20 mg/kg). Buprenorphine alone exhibited a bell shaped dose response inhibition of respiration; however the plateau of the dose response inhibition on respiration was lost when administered in combination with diazepam. Methadone showed a dose-dependent inhibitory effect on respiration, which was potentiated with diazepam pretreatment. While the effect of diazepam pretreatment was the abolishment of the protective bell shaped dose response effect on respiration, the effect of buprenorphine and diazepam was not greater than methadone and diazepam.