Butyrylcholinesterase gene mutations in patients with prolonged apnea after succinylcholine for electroconvulsive therapy

Risk Assessment of Electroconvulsive Therapy in Clinical Routine: A 3-Year Analysis of Life-Threatening Events in More Than 3,000 Treatment Sessions

Background: Extensive research has reported that electroconvulsive therapy (ECT) can be highly effective in approximately 80% of patients suffering from depression. Its clinical use is mainly limited by historical objections and the concern about unwanted adverse effects (AEs), including serious and potentially life-threatening adverse events (pLTAEs), induced either by ECT or by anesthesia. Objective risk estimation is, therefore, a decisive factor in determining an indication for ECT. Methods: This paper presents a retrospective analysis of 3-year safety protocols and patient files of 157 patients who received a total of 3,106 ECT applications in a psychiatric inpatient setting at a psychiatric community hospital. This patient group comprises 5.3% of inpatients admitted with comparable diagnoses. Adverse events were analyzed from standardized safety protocols and patient files with a focus on pLTAEs. Results: Adverse events were reported for 30 (19.1%) of the 157 participants during 39 (6.1%) of 641 hospital stays. Serious pLTAEs occurred during three electroconvulsive stimulations in three patients, who needed action through the administration of medication or mechanical respiration. No patient suffered permanent damage to health, and no patient died. The incidence of these and other AEs was independent of sex, age, and diagnosis of patients, and anesthesia medication. Minor AEs occurred more often with higher stimulus doses and an increasing number of treatments. Conclusion: The low incidence rate of 0.097% of serious pLTAEs that require medical action may allow the conclusion that ECT is a rather safe treatment when performed in a controlled setting. The beneficial risk profile of ECT performed in the standard care of psychiatric hospitals suggests a more generous indication of this treatment method. We recommend that ECT facilities collect individual safety data to allow a reliable judgment of their institutional ECT risk profile.

<p>Genetic Testing for <em>BCHE</em> Variants Identifies Patients at Risk of Prolonged Neuromuscular Blockade in Response to Succinylcholine</p>

Background

Genetic variants in the BCHE (butyrylcholinesterase) gene are associated with reduced BChE enzyme activity and prolonged post-succinylcholine neuromuscular blockade, which can lead to postanesthetic apnea and respiratory depression. Testing for BChE deficiency is usually performed by biochemical methods and is generally only offered to patients who have a personal or family history of prolonged post-succinylcholine neuromuscular blockade.

Purpose

Using a clinical test, we investigated the frequencies of BCHE genotypes that are associated with increased risk for prolonged post-succinylcholine neuromuscular blockade.

Materials and Methods

Five BCHE variants, including the A (atypical, rs1799807), K (Kalow, rs1803274), F₁ (fluoride-1, rs28933389), F₂ (fluoride-2, rs28933390), and S₁ (silent-1, rs398124632), were genotyped in a large (n = 13,301), multi-ethnic cohort in the United States. Subjects were recipients of pharmacogenetic testing ordered by their physicians as part of routine care.

Results

The minor allele frequencies of A, K, F₁, F₂, and S₁ were 1.60%, 19.93%, 0.08%, 0.47%, and 0.04%, respectively, in this cohort. Based on a review of biochemical and clinical data of these variants, we grouped BCHE genotypes into four phenotypic categories to stratify the risk for prolonged post-succinylcholine neuromuscular blockade. Approximately 0.06% of patients were predicted to have severe BChE deficiency, 8% were predicted to have moderate BChE deficiency, and 29% were predicted to have mild BChE deficiency. Compared to other ethnic groups, Caucasians were predicted to have the highest frequency of BChE deficiency.

Conclusion

While severe BChE deficiency is rare in the United States, approximately 8% of Americans are at moderate risk of prolonged post-succinylcholine neuromuscular blockade, suggesting that a sizable percentage of patients may benefit from preoperative genetic testing of BCHE.

Systemic Absorption of Cyclopentolate and Adverse Events After Retinopathy of Prematurity Exams

PURPOSE

Preterm infants undergoing Retinopathy of Prematurity Eye Exams (ROPEE) may experience adverse events, possibly from systemic absorption of cyclopentolate. The purpose of this study was to analyze the association between adverse events and drug levels found in neonates undergoing ROPEE.

MATERIALS AND METHODS

25 infants were randomized into two groups during routine ROP screening: 5 infants for blood collection before mydriatic drops and 20 for blood collection 1 h after eye drops. Blood was collected onto dried blood spot cards, extracted, and analyzed for cyclopentolate and phenylephrine using liquid chromatography and mass spectrometry. Relationships between drug levels and adverse events were assessed.

RESULTS

Cyclopentolate (range 6-53 ng/ml) was observed in 15 of 18 infants, while phenylephrine was not detected. Levels of cyclopentolate were significantly higher in infants who were on oxygen (p = 0.01). There was a significant association between cyclopentolate levels and gastric residuals in tube-fed infants not receiving oxygen (p = 0.01).

CONCLUSIONS

Cyclopentolate levels varied among preterm infants after ROPEE. Cyclopentolate was positively associated with increased gastric residuals. Underlying medical conditions requiring oxygen administration may affect absorption and metabolism of cyclopentolate. There is a need to predict infants at risk for high blood levels of cyclopentolate in order to prevent or treat adverse events after ROPEE.

Awareness during emergence from anaesthesia: significance of neuromuscular monitoring in patients with butyrylcholinesterase deficiency

BACKGROUND

Butyrylcholinesterase deficiency can result in prolonged paralysis after administration of succinylcholine or mivacurium. We conducted an interview study to assess whether patients with butyrylcholinesterase deficiency were more likely to have experienced awareness during emergence from anaesthesia if neuromuscular monitoring had not been applied.

METHODS

Patients referred during 2004-2012 were included. Data on the use of neuromuscular monitoring were available from a previous study. Interviews, conducted by telephone, included questions about awareness and screening for post-traumatic stress disorder. Reports of panic, hopelessness, suffocation, or a feeling of being dead or dying resulted in the experience being classified further as distressful. Patients were categorized as aware or unaware by investigators blinded to use of neuromuscular monitoring.

RESULTS

Ninety-five patients were eligible to be interviewed. Of the 70 patients interviewed, 35 (50%) were aware while paralysed during emergence. Of these, 28 (80%) were not monitored with a nerve stimulator when awakened, compared with 17 (49%) of the 35 unaware patients (P=0.012, Fisher's exact test). Thirty (86%) aware patients reported distress compared with seven (20%) unaware patients (P<0.001). The aware patients scored higher in screening for post-traumatic stress disorder (P=0.006, Mann-Whitney U-test).

CONCLUSIONS

Butyrylcholinesterase deficiency is a major risk factor for distressing awareness during emergence. Lack of neuromuscular monitoring increases the risk significantly. Neuromuscular monitoring should be applied even when using short-acting neuromuscular blocking agents.

Pharmacogenetics in electroconvulsive therapy and adjunctive medications

Electroconvulsive therapy (ECT) has shown apparent efficacy in treatment of patients with depression and other mental illnesses who do not respond to psychotropic medications or need urgent control of their symptoms. Pharmacogenetics contributes to an individual's sensitivity and response to a variety of drugs. Clinical insights into pharmacogenetics of ECT and adjunctive medications not only improves its safety and efficacy in the indicated patients, but can also lead to the identification of novel treatments in psychiatric disorders through understanding of potential molecular and biological mechanisms involved. In this review, we explore the indications of pharmacogenetics role in safety and efficacy of ECT and present the evidence for its role in patients with psychiatric disorders undergoing ECT.

Use of neuromuscular monitoring to detect prolonged effect of succinylcholine or mivacurium: three case reports

Mutations in the butyrylcholinesterase gene can lead to a prolonged effect of the neuromuscular blocking agents, succinylcholine and mivacurium. If the anaesthesiologist is not aware of this condition, it may result in insufficient respiration after tracheal extubation. However, this can be avoided with the use of objective neuromuscular monitoring if used adequately. Three case reports of prolonged effect of succinylcholine or mivacurium were presented to illustrate the importance of neuromuscular monitoring during anaesthesia. In the first case, continuous intraoperative neuromuscular monitoring allowed a prolonged neuromuscular blockade to be discovered prior to tracheal extubation of the patient. The patient was extubated after successful reversal of the neuromuscular blockade. On the contrary, neuromuscular monitoring was not used during anaesthesia in the second patient; hence, the prolonged effect of the neuromuscular blocking agent was not discovered until after extubation. In the third patient, the lack of response to nerve stimulation was interpreted as a technical failure and the prolonged effect of succinylcholine was discovered when general anaesthesia was terminated. Both patients had insufficient respiration. They were therefore re-sedated, transferred to the intensive care unit and the tracheas were extubated after full recovery from neuromuscular blockade. We recommend the use of monitoring every time these agents are used, even with short-acting drugs like succinylcholine and mivacurium.

Reversal of succinylcholine induced apnea with an organophosphate scavenging recombinant butyrylcholinesterase

BACKGROUND

Concerns about the safety of paralytics such as succinylcholine to facilitate endotracheal intubation limit their use in prehospital and emergency department settings. The ability to rapidly reverse paralysis and restore respiratory drive would increase the safety margin of an agent, thus permitting the pursuit of alternative intubation strategies. In particular, patients who carry genetic or acquired deficiency of butyrylcholinesterase, the serum enzyme responsible for succinylcholine hydrolysis, are susceptible to succinylcholine-induced apnea, which manifests as paralysis, lasting hours beyond the normally brief half-life of succinylcholine. We hypothesized that intravenous administration of plant-derived recombinant BChE, which also prevents mortality in nerve agent poisoning, would rapidly reverse the effects of succinylcholine.

METHODS

Recombinant butyrylcholinesterase was produced in transgenic plants and purified. Further analysis involved murine and guinea pig models of succinylcholine toxicity. Animals were treated with lethal and sublethal doses of succinylcholine followed by administration of butyrylcholinesterase or vehicle. In both animal models vital signs and overall survival at specified intervals post succinylcholine administration were assessed.

RESULTS

Purified plant-derived recombinant human butyrylcholinesterase can hydrolyze succinylcholine in vitro. Challenge of mice with an LD100 of succinylcholine followed by BChE administration resulted in complete prevention of respiratory inhibition and concomitant mortality. Furthermore, experiments in symptomatic guinea pigs demonstrated extremely rapid succinylcholine detoxification with complete amelioration of symptoms and no apparent complications.

CONCLUSIONS

Recombinant plant-derived butyrylcholinesterase was capable of counteracting and reversing apnea in two complementary models of lethal succinylcholine toxicity, completely preventing mortality. This study of a protein antidote validates the feasibility of protection and treatment of overdose from succinylcholine as well as other biologically active butyrylcholinesterase substrates.

Recovery of residual curarization after red blood cell transfusion

Background

The muscle-relaxing effects of succinylcholine are terminated via hydrolysis by plasma cholinesterase. There are multiple genetic variants of this enzyme and clinical circumstances that might influence the activity of plasma cholinesterase and eventually lead to prolonged neuromuscular blockade following succinylcholine application.

Case Report

Here, we report a parturient woman with atonic bleeding who suffered significant blood loss (hemoglobin 6.0 g·dL⁻¹). For surgical curettage, general anesthesia was performed by using short-acting succinylcholine. By the end of the 105-minute procedure, the patient’s trachea was extubated. After extubation she showed signs of the prolonged neuromuscular blocking action of succinylcholine. At this time, the patient received an AB0-compatible red blood cell transfusion and recovered instantly from neuromuscular blockade. The plasma cholinesterase (3.200 U·L⁻¹) was below the normal range (4.900–12.000 U·L⁻¹). Patient’s blood DNA analysis revealed heterozygously the genetic K variant of plasma cholinesterase. After red blood cell transfusion, serum potassium was elevated (5.7 mmol·L⁻¹; 4.4 mmol·L⁻¹ prior to transfusion).

Conclusions

Pregnancy, blood loss and genetic variation contributed to impairment of plasma cholinesterase. Due to high-speed red blood cell transfusion, hemolytic release of erythrocyte cholinesterase might have terminated the neuromuscular blocking succinylcholine effect.

Prolonged apnea during electroconvulsive therapy in monozygotic twins: case reports

In the present work, we report two cases of monozygotic twins who developed prolonged apnea during electroconvulsive therapy (ECT) as a complication of anesthesia. In both cases, prolonged action of succinylcholine caused by a butyrylcholinesterase (BCHE) deficiency was confirmed by means of the dibucaine number test. In both cases, genetic analysis using the polymerase chain reaction revealed haplotype combined A and K variant mutations of the BCHE gene, both in the heterozygous form. These data show the potential risk of BCHE deficiency as a complication of anesthesia during ECT, and in particular underline the possible genetic contribution within a complex pathogenetic model.