Propylene Glycol Toxicity Complicating Use of Barbiturate Coma

"Should We Phenobarb-it-All?" A Phenobarbital-Based Protocol for Non-Intensive Care Unit Trauma Patients at High Risk of or Experiencing Alcohol Withdrawal

BACKGROUND

Alcohol use is frequent in trauma patients and alcohol withdrawal syndrome (AWS) is associated with significant morbidity. Benzodiazepines are commonly used for AWS, but may cause neurologic and respiratory adverse events (AEs). The objective was to evaluate the effectiveness and safety of a phenobarbital-based protocol for the treatment of AWS in non-intensive care unit (ICU) trauma patients.

METHODS

Adult non-ICU trauma patients at high risk of or experiencing AWS PRE and POST implementation of a phenobarbital-based protocol were included. Outcomes were AWS-related complications (AWS-RC), benzodiazepine use, adjunctive medication use, hospital length of stay (HLOS), and medication-related AEs. Subgroup analyses were performed on patients with traumatic brain injury (TBI), rib fractures, and at high risk of severe AWS.

RESULTS

Overall, 110 patients were included (51 PRE, 59 POST). AWS-RC developed in 17 PRE patients compared to 10 POST patients (33% vs 17%; P = .05). PRE patients were more likely to receive benzodiazepines (88% vs 42%, P < .0001) and higher total dose (11 vs 4 mg lorazepam equivalent; P = .001). No difference noted in HLOS (8 vs 8 days, P = .27), adjunctive medication use (49% vs 54%, P = .60), or AEs (57% vs 39%, P = .06). There was no difference in AWS-RC in the TBI subgroup (P = .19), less AEs in the rib fracture POST subgroup (P = .04), and less AWS-RC in the high risk of severe AWS POST subgroup (P = .03).

DISCUSSION

A phenobarbital-based protocol in trauma patients is effective in preventing AWS-RC and decreasing benzodiazepine use without increasing AEs.

Refractory and Super-refractory Status Epilepticus

Context

Refractory status epilepticus (RSE) and super-refractory status epilepticus (SRSE) are neurological emergencies with considerable mortality and morbidity. In this paper, we provide an overview of causes, evaluation, treatment, and consequences of RSE and SRSE, reflecting the lack of high-quality evidence to inform therapeutic approach.

Sources

This is a narrative review based on personal practice and experience. Nevertheless, we searched MEDLINE (using PubMed and OvidSP vendors) and Cochrane central register of controlled trials, using appropriate keywords to incorporate recent evidence.

Results

Refractory status epilepticus is commonly defined as an acute convulsive seizure that fails to respond to two or more anti-seizure medications including at least one nonbenzodiazepine drug. Super-refractory status epilepticus is a status epilepticus that continues for ≥24 hours despite anesthetic treatment, or recurs on an attempted wean of the anesthetic regimen. Both can occur in patients known to have epilepsy or de novo, with increasing recognition of autoimmune and genetic causes. Electroencephalography monitoring is essential to monitor treatment response in refractory/super-refractory status epilepticus, and to diagnose non-convulsive status epilepticus. The mainstay of treatment for these disorders includes anesthetic infusions, primarily midazolam, ketamine, and pentobarbital. Dietary, immunological, and surgical treatments are viable in selected patients. Management is challenging due to multiple acute complications and long-term adverse consequences.

Conclusions

We have provided a synopsis of best practices for diagnosis and management of refractory/superrefractory status epilepticus and highlighted the lack of sufficient high-quality evidence to drive decision making, ending with a brief foray into avenues for future research.

Cerebral Edema and Elevated Intracranial Pressure

PURPOSE OF REVIEW

This article reviews the management of cerebral edema, elevated intracranial pressure (ICP), and cerebral herniation syndromes in neurocritical care.

RECENT FINDINGS

While corticosteroids may be effective in reducing vasogenic edema around brain tumors, they are contraindicated in traumatic cerebral edema. Mannitol and hypertonic saline use should be tailored to patient characteristics including intravascular volume status. In patients with traumatic brain injury who are comatose, elevated ICP should be managed with an algorithmic, multitiered treatment protocol to maintain an ICP of 22 mm Hg or less. Third-line ICP treatments include anesthetic agents, induced hypothermia, and decompressive craniectomy. Recent clinical trials have demonstrated that induced hypothermia and decompressive craniectomy are ineffective as early neuroprotective strategies and should be reserved for third-line management of refractory ICP elevation in severe traumatic brain injury. Monitoring for cerebral herniation should include bedside pupillometry in supratentorial space-occupying lesions and recognition of upward herniation in patients with posterior fossa lesions.

SUMMARY

Although elevated ICP, cerebral edema, and cerebral herniation are interrelated, treatments should be based on the distinct pathophysiologic process. Focal lesions resulting in brain compression are primarily managed with surgical decompression, whereas global or multifocal brain injury requires a treatment protocol that includes medical and surgical interventions.

Iatrogenic Propylene Glycol Intoxication Due to High-Dose Pentobarbital for Refractory Intracranial Hypertension: A Case Report

Propylene glycol is a rarely reported toxicity from high-dose administration of certain intravenous drugs, including lorazepam and pentobarbital. We present a case of iatrogenic propylene glycol toxicity secondary to a high-dose pentobarbital infusion for the treatment of refractory intracranial hypertension due to cerebral venous sinus thrombosis. The patient developed metabolic acidosis and acute kidney failure secondary to propylene glycol toxicity. After initiation of continuous renal replacement therapy, the patient's acute renal failure and lactic acidosis resolved. Using the Naranjo scale, this case received a score of 5, defining it as a "probable" adverse drug event. In patients who develop lactic acidosis and acute renal failure after initiation of high-dose pentobarbital, propylene glycol toxicity should be higher up in the differential diagnosis. Monitoring the serum osmolality while on pentobarbital could help provide valuable information to prevent iatrogenic propylene glycol toxicity.

A Review of Agents for Palliative Sedation/Continuous Deep Sedation: Pharmacology and Practical Applications

Continuous deep sedation at the end of life is a specific form of palliative sedation requiring a care plan that essentially places and maintains the patient in an unresponsive state because their symptoms are refractory to any other interventions. Because this application is uncommon, many providers may lack practical experience in this specialized area and resources they can access are outdated, nonspecific, and/or not comprehensive. The purpose of this review is to provide an evidence- and experience-based reference that specifically addresses those medications and regimens and their practical applications for this very narrow, but vital, aspect of hospice care. Patient goals in a hospital and hospice environments are different, so the manner in which widely used sedatives are dosed and applied can differ greatly as well. Parameters applied in end-of-life care that are based on experience and a thorough understanding of the pharmacology of those medications will differ from those applied in an intensive care unit or other medical environments. By recognizing these different goals and applying well-founded regimens geared specifically for end-of-life sedation, we can address our patients' symptoms in a more timely and efficacious manner.

Observed medical and surgical complications of prolonged barbiturate coma for refractory status epilepticus

BACKGROUND

Refractory status epilepticus is often treated with third-line therapy, such as pentobarbital coma. However, its use is limited by side effects. Recognizing and preventing major and minor adverse effects of prolonged pentobarbital coma may increase good outcomes. This study retrospectively reviewed direct and indirect medical and surgical pentobarbital coma.

METHODS

Retrospective chart review of all patients with refractory status epilepticus treated with pentobarbital over a 1 year period at a large tertiary care center. We collected baseline data, EEG data, and complications that were observed.

RESULTS

Overall, nine patients [median age 46.4 (IQR 21.7, 75.5) years] were induced with pentobarbital coma median 11 (IQR 3, 33) days after seizure onset for a median of 9 (IQR 3.5, 45.4) days. A total of four to eight concurrent antiepileptics were tried prior to the pentobarbital coma. Phenobarbital, due to recurrence of seizures on weaning pentobarbital coma, was required in seven patients. Observed complications included peripheral neuropathy (77.8%), cerebral atrophy (33.3%), volume overload (44.4%), renal/metabolic (77.8%), gastrointestinal (66.6%), endocrine (55.6%), cardiac/hemodynamic/vascular (77.8%), respiratory (100%), and infectious (77.8%). The number of complications trended with duration of induced coma but was nonsignificant. Median ICU length of stay was 40 (IQR 28, 97.5) days. Overall, five patients were able to follow commands after a median 37 (IQR 25.5, 90) days from coma onset. There were eight patients that were discharged from hospital with three remaining in a prolonged unresponsive state. There was one patient that died prior to discharge.

CONCLUSIONS

This study highlights the high morbidity in patients with refractory status epilepticus requiring pentobarbital coma. Anticipating and addressing the indirect and direct complications in prolonged pentobarbital coma may improve survival and functional outcomes in patients with refractory status epilepticus.

Treatment of Convulsive Status Epilepticus

OPINION STATEMENT

Convulsive status epilepticus (CSE) is a medical emergency with an associated high mortality and morbidity. It is defined as a convulsive seizure lasting more than 5 min or consecutive seizures without recovery of consciousness. Successful management of CSE depends on rapid administration of adequate doses of anti-epileptic drugs (AEDs). The exact choice of AED is less important than rapid treatment and early consideration of reversible etiologies. Current guidelines recommend the use of benzodiazepines (BNZ) as first-line treatment in CSE. Midazolam is effective and safe in the pre-hospital or home setting when administered intramuscularly (best evidence), buccally, or nasally (the latter two possibly faster acting than intramuscular (IM) but with lower levels of evidence). Regular use of home rescue medications such as nasal/buccal midazolam by patients and caregivers for prolonged seizures and seizure clusters may prevent SE, prevent emergency room visits, improve quality of life, and lower health care costs. Traditionally, phenytoin is the preferred second-line agent in treating CSE, but it is limited by hypotension, potential arrhythmias, allergies, drug interactions, and problems from extravasation. Intravenous valproate is an effective and safe alternative to phenytoin. Valproate is loaded intravenously rapidly and more safely than phenytoin, has broad-spectrum efficacy, and fewer acute side effects. Levetiracetam and lacosamide are well tolerated intravenous (IV) AEDs with fewer interactions, allergies, and contraindications, making them potentially attractive as second- or third-line agents in treating CSE. However, data are limited on their efficacy in CSE. Ketamine is probably effective in treating refractory CSE (RCSE), and may warrant earlier use; this requires further study. CSE should be treated aggressively and quickly, with confirmation of treatment success with epileptiform electroencephalographic (EEG), as a transition to non-convulsive status epilepticus is common. If the patient is not fully awake, EEG should be continued for at least 24 h. How aggressively to treat refractory non-convulsive SE (NCSE) or intermittent non-convulsive seizures is less clear and requires additional study. Refractory SE (RSE) usually requires anesthetic doses of anti-seizure medications. If an auto-immune or paraneoplastic etiology is suspected or no etiology can be identified (as with cryptogenic new onset refractory status epilepticus, known as NORSE), early treatment with immuno-modulatory agents is now recommended by many experts.

Systemic complications of status epilepticus--An update

Systemic complications occur at every stage of status epilepticus, involve every organ system, and may worsen outcome. Initially, there is a massive catecholamine release and hyperadrenergic state that may result in neurocardiogenic, pulmonary, and, sometimes, musculoskeletal or renal injury. Further medical complications accompany the various treatments used to abort the seizures including the use of nonanesthetic antiseizure drugs and high-dose anesthetic infusions. Later, sequelae of prolonged immobility and critical illness occur and add to the cumulative morbidity of these patients. Clinicians should follow a protocol to guide screening for early markers of systemic injury, complications of specific pharmacologic and adjunctive treatments, and periodic surveillance for complications related to prolonged immobility. This article is part of a Special Issue entitled "Status Epilepticus".

Treatment of Generalized Convulsive Status Epilepticus in Pediatric Patients

Generalized convulsive status epilepticus (GCSE) is one of the most common neurologic emergencies and can be associated with significant morbidity and mortality if not treated promptly and aggressively. Management of GCSE is staged and generally involves the use of life support measures, identification and management of underlying causes, and rapid initiation of anticonvulsants. The purpose of this article is to review and evaluate published reports regarding the treatment of impending, established, refractory, and super-refractory GCSE in pediatric patients.

Severe propylene glycol toxicity secondary to use of anti-epileptics

Propylene glycol toxicity presenting as high anion gap metabolic acidosis and osmolar gap has been extensively reported in literature, and most of them are secondary to intravenous lorazepam infusion. However, propylene glycol is used as a solvent in a number of medications that are frequently utilized in critical care setting, and hence one should be aware that the toxicity is possible from a variety of medication. Phenobarbital and phenytoin are one of those, and we hereby report a novel case of propylene glycol toxicity secondary to phenobarbital and phenytoin infusion in a patient with refractory status epilepticus. Furthermore, our patient had end-stage renal disease, which we think could have been an important precipitating factor for the toxicity. Because most of the symptoms from propylene glycol toxicity can mimic sepsis-which is very common in critical care unit patients-this life threatening scenario could be easily missed. Regular monitoring of osmolar gap is an easily available intervention in the at risk patients.

Chronic maxillary sinusitis caused by root canal overfilling of Calcipex II

This is a case report of chronic maxillary sinusitis caused by root canal overfilling of Calcipex II (Techno-Dent). A 60 year-old male complained of dull pain in the right maxillary molar area after complicated endodontic treatment using Calcipex II paste and was finally diagnosed with a chronic maxillary sinusitis through a clinical and radiological observation. In the biopsy examination, the periapical granuloma contained a lot of dark and translucent Calcipex II granules which were not stained with hematoxylin and eosin. They were usually engulfed by macrophages but rarely resorbed, resulting in scattering and migrating into antral mucosa. Most of the Calcipex II granules were also accumulated in the cytoplasms of secretory columnar epithelial cells, and small amount of Calcipex II granules were gradually secreted into sinus lumen by exocytosis. However, chronic granulomatous inflammation occurred without the additional recruitment of polymorphonuclear leukocytes (PMNs) and lymphocytes, and many macrophages which engulfed the Calcipex II granules were finally destroyed in the processes of cellular apoptosis. It is presumed that Calcipex II granules are likely to have a causative role to induce the granulomatous foreign body inflammation in the periapical region, and subsequently to exacerbate the chronic maxillary sinusitis in this study.

The multifaceted care of status epilepticus

After seizures have been controlled, long-term care of status epilepticus may be needed and collectively involves every major organ. First, as a result of rapid escalation of antiepileptic drugs, there are initial concerns with hypotension, acid-base abnormalities, and cardiac arrhythmias. Second, refractory status epilepticus and the continuous need for intravenous administration of anesthetic drugs will lead to a multitude of systemic complications that require long-term complex care. Most anticipated problems are infectious complications with a high risk of pneumonia and sepsis, but thromboembolism due to immobilization and catheter placement are also common. If a good outcome is possible or anticipated in a patient with refractory status epilepticus, physicians should plan for a surveillance and treatment protocol to adequately support these patients.

Falsely elevated sodium levels during thiopental treatment in the ICU: technical interference on a laboratory device with important clinical relevance

INTRODUCTION

Thiopental is a cornerstone in the treatment of refractory status epilepticus and intractable intracranial hypertension. In our center we observed that thiopental might cause falsely elevated serum sodium levels.

METHODS

Triggered by a recent case experience of extremely elevated serum sodium levels during thiopental treatment, we retrospectively identified 53 patients treated with thiopental in our intensive care unit between 2007 and 2011 and evaluated electrolyte changes. We differentiated the analysis before and after introduction of a new device for sodium assays (Dimension Vista, Siemens) in the central laboratory in April 2010. Standardized in vitro laboratory tests were performed to study the effect of thiopental on sodium analysis.

RESULTS

Before April 2010, serum sodium levels determined in the central laboratory showed a good agreement with the bedside point-of-care (POC) device during thiopental therapy with [sodium](laboratory) - [sodium](POC) of only 1.08 mmol/L (P = .0517). After April 2010, a strong discrepancy between laboratory values and POC values was observed with [sodium](laboratory) - [sodium](POC) = 11.57 mmol/L (P < .0001). Standardized in vitro testing confirmed that thiopental induced a dose-dependent false hypernatremia (P = .002).

CONCLUSIONS

Thiopental treatment can result in falsely elevated serum sodium. This is a critical finding since high sodium levels preclude administrating mannitol or hypertonic saline for the treatment of elevated intracranial pressure. Moreover, a false high sodium level might lead to the inappropriate administration of hypotonic fluids potentially resulting in increased brain edema and even higher intracranial pressure. To our knowledge, this is the first paper describing this clinically relevant phenomenon.

Propylene glycol produces excessive apoptosis in the developing mouse brain, alone and in combination with phenobarbital

INTRODUCTION

Propylene glycol (PG) is a common solvent used in medical preparations. It is generally recognized as safe at regulated concentrations; however, its apoptotic potential is unknown.

RESULTS

PG triggered widespread apoptotic neurodegeneration with the greatest damage at postnatal day 7 (P7). Significant apoptosis was observed at doses as low as 2 ml/kg. These findings have implications for the safety of drug preparations used in pediatric medicine. The anticonvulsant phenobarbital (PB), which alone produces apoptosis in the immature central nervous system (CNS) is prepared in 68% PG and 10% ethanol (EtOH). We assessed whether PG contributes to the neurotoxic potential of PB. The agents (both at subtoxic doses) produce significantly more apoptosis when used in combination.

DISCUSSION

In conclusion, finding an alternative non-apoptotic solvent that can be used as a substitute for PG may be beneficial to patients.

METHODS

C57BL/6 mice (P4-30) were exposed to PG to examine whether PG could produce apoptosis in the developing CNS.

Adverse drug events associated with the use of analgesics, sedatives, and antipsychotics in the intensive care unit

As critically ill patients frequently receive analgesics, sedatives, and antipsychotics to optimize patient comfort and facilitate mechanical ventilation, adverse events associated with the use of these agents can affect all organ systems and result in substantial morbidity and mortality. Although many of these adverse effects are common pharmacologic manifestations of the agent, and therefore frequently reversible, others are idiosyncratic and thus unexpected. The critically ill are more susceptible to adverse drug events than nonintensive care unit patients due to the high doses and long periods for which each of these agents are often administered, the frequent use of intravenous formulations that contain adjuvants that may lead to toxicity in some instances, and the high prevalence of end-organ dysfunction that affects the pharmacokinetic and pharmacodynamic response to therapy. This paper will review the most common and serious adverse drug events reported to occur with the use of sedatives, analgesics, and antipsychotics in the intensive care unit; highlight the pharmacokinetic, pharmacodynamic, and pharmacogenetic factors that can influence analgesic, sedative, and antipsychotic response and safety in the critically ill; and identify strategies that can be used to minimize toxicity with these agents.

Phenobarbital treatment in a patient with resistant alcohol withdrawal syndrome

Alcohol withdrawal syndrome (AWS) is a major cause of morbidity and mortality in the acute care setting. We describe a 28-year-old man who was brought to the emergency department with a new-onset seizure and clinical signs and symptoms consistent with advanced delirium tremens. A symptom-triggered intensive care unit treatment protocol consisting of a benzodiazepine and antiadrenergic agents was started. The manifestations of delirium tremens persisted with titration of a lorazepam infusion in excess of 40 mg/hour. Intravenous phenobarbital was administered in escalating doses of 65 mg followed by 130 mg 15 minutes later, resulting in control of severe agitation in the face of benzodiazepine resistance. Subsequent scheduled phenobarbital administration allowed for a successful and orderly weaning of the continuous benzodiazepine infusion and adjunctive agents used in AWS management. With continued clearing of consciousness, the patient was successfully discharged. The administration of phenobarbital in this patient allowed improved symptom control, minimized the potential for propylene glycol toxicity, was not associated with respiratory depression, and facilitated successful weaning of benzodiazepines. Barbiturates offer a mechanism of action that is different from that of benzodiazepines. Although the cornerstone of treatment for AWS remains benzodiazepines, this case highlights the potential utility of phenobarbital in patients with resistant AWS.