Pathophysiology of hyperkalemia induced by succinylcholine

Electrolyte Disturbances Related to Sodium and Potassium and Electroconvulsive Therapy: A Systematic Review

INTRODUCTION

Electrolyte disturbances related to sodium and potassium affect patients with mental disorders undergoing electroconvulsive therapy (ECT). The objective of this study was to systematically summarize the data regarding ECT and electrolyte disturbances related to sodium and potassium.

MATERIALS AND METHODS

A systematic literature review in accordance with PRISMA guidelines was conducted. Clinical studies of patients receiving ECT with electrolyte disturbances reported before or after treatment were included.

RESULTS

We identified nine case reports and two retrospective studies describing electrolyte abnormalities occurring before or after ECT. ECT was effective and safe in patients with hyponatremia and hypernatremia, including the elderly patient population. This treatment was also effective in treating psychiatric symptoms that may persist after ionic equalization. Electrolyte disturbances after ECT were rare. Reports have suggested that succinylcholine used as a muscle relaxant was the main cause of hyperkalemia after ECT.

CONCLUSIONS

Electrolyte control is a crucial aspect of guiding ECT therapy. In the context of sodium-related disorders, it is critical to control patient hydration as part of therapy. In addition, succinylcholine should not be used in patients with immobilization, such as catatonia or neuroleptic malignant syndrome. It is necessary to conduct further studies to clarify whether electrolyte concentration affects ECT parameters and clinical efficacy. In addition, it is necessary to assess the influence of various anesthetics on these conditions during ECT. The result of this review should be interpreted bearing in mind the small number of studies conducted to date and the low quality of the evidence they provide.

BDNF Spinal Overexpression after Spinal Cord Injury Partially Protects Soleus Neuromuscular Junction from Disintegration, Increasing VAChT and AChE Transcripts in Soleus but Not Tibialis Anterior Motoneurons

After spinal cord transection (SCT) the interaction between motoneurons (MNs) and muscle is impaired, due to reorganization of the spinal network after a loss of supraspinal inputs. Rats subjected to SCT, treated with intraspinal injection of a AAV-BDNF (brain-derived neurotrophic factor) construct, partially regained the ability to walk. The central effects of this treatment have been identified, but its impact at the neuromuscular junction (NMJ) has not been characterized. Here, we compared the ability of NMJ pre- and postsynaptic machinery in the ankle extensor (Sol) and flexor (TA) muscles to respond to intraspinal AAV-BDNF after SCT. The gene expression of cholinergic molecules (VAChT, ChAT, AChE, nAChR, mAChR) was investigated in tracer-identified, microdissected MN perikarya, and in muscle fibers with the use of qPCR. In the NMJs, a distribution of VAChT, nAChR and Schwann cells was studied by immunofluorescence, and of synaptic vesicles and membrane active zones by electron microscopy. We showed partial protection of the Sol NMJs from disintegration, and upregulation of the VAChT and AChE transcripts in the Sol, but not the TA MNs after spinal enrichment with BDNF. We propose that the observed discrepancy in response to BDNF treatment is an effect of difference in the TrkB expression setting BDNF responsiveness, and of BDNF demands in Sol and TA muscles.

Suxamethonium-Induced Hyperkalemia: A Short Review of Causes and Recommendations for Clinical Applications

After the introduction of suxamethonium in 1953, cases of cardiac arrest during induction of anesthesia were recorded. In the following years, hyperkalemia was identified as the cause, and the connection to acetylcholine receptor modulation as the underlying molecular mechanism was made. Activation of the acetylcholine receptor with suxamethonium, acetylcholine, or choline causes an efflux of potassium to the extracellular space. However, certain pathological conditions cause acetylcholine receptor proliferation and the emergence of immature receptors capable of a larger potassium efflux to the bloodstream. These pathologic conditions include upper and lower neuron injuries, major burns, trauma, immobility, muscle tumors, muscular dystrophy, and prolonged critical illness. The latter is more important and relevant than ever due to the increasing number of COVID-19 patients requiring prolonged respiratory support and consequent immobilization. Suxamethonium can be used safely in the vast majority of patients. Still, reports of lethal hyperkalemic responses to suxamethonium continue to emerge. This review serves as a reminder of the pathophysiology behind extensive potassium release. Proficiency in the use of suxamethonium includes identification of patients at risk, and selection of an alternative neuromuscular blocking agent is imperative.

Laryngotracheal Reconstruction in the Pediatric Burn Patient: Surgical Techniques and Decision Making

The management of laryngotracheal stenosis (LTS) in the pediatric burn patient is complex and requires a multidisciplinary approach. The mainstay of treatment for LTS is laryngotracheal reconstruction (LTR), however, limited reports of burn-specific LTR techniques exist. Here, we provide insight into the initial airway evaluation, surgical decision making, anesthetic challenges, and incision modifications based on our experience in treating patients with this pathology. The initial airway evaluation can be complicated by microstomia, trismus, and neck contractures-the authors recommend treatment of these complications prior to initial airway evaluation to optimize safety. The surgical decision making regarding pursuing single-stage LTR, double-stage LTR, and 1.5-stage LTR can be challenging-the authors recommend 1.5-stage LTR when possible due to the extra safety of rescue tracheostomy and the decreased risk of granuloma, which is especially important in pro-inflammatory burn physiology. Anesthetic challenges include obtaining intravenous access, securing the airway, and intravenous induction-the authors recommend peripherally inserted central catheter when appropriate, utilizing information from the initial airway evaluation to secure the airway, and avoidance of succinylcholine upon induction. Neck and chest incisions are often within the TBSA covered by the burn injury-the authors recommend modifying typical incisions to cover unaffected skin whenever possible in order to limit infection and prevent wound healing complications. Pediatric LTR in the burn patient is challenging, but can be safe when the surgeon is thoughtful in their decision making.

Malignant Hyperthermia Susceptibility and Related Diseases

This review identifies disease states associated with malignant hyperthermia susceptibility based on genotypic and phenotypic findings, and a framework is established for clinicians to identify a potentially malignant hyperthermia–susceptible patient.

Rapid Sequence Induction and Intubation

The modern version of RSI starts with preoxygenation. General anaesthesia is then induced using a rapid acting intravenous anaesthetic and a rapid acing muscle relaxant. Cricoid pressure is applied by an experienced assistant during induction, which should then be maintained until the trachea of the patient is intubated, correct positioning of the tracheal tube confirmed and the cuff inflated. The patient is conventionally not ventilated during this phase but critically ill patients are exceptions. The patient's tracheal should be intubated when adequately paralysed and its position verified. The assistant can then relieve the cricoid pressure and the tracheal tube fixed.

Effectiveness of interventions to improve medication use during rapid-sequence intubation in a pediatric emergency department

PURPOSE

Results of a study to determine whether checklist-based interventions improved the selection and administration of rapid-sequence intubation (RSI) medications in a pediatric emergency department (ED) are reported.

METHODS

A retrospective study of data collected during a quality-improvement project was conducted. Data sources included the electronic health record and video review. The central intervention was use of a 21-item RSI checklist, which included guidance for the physician team leader on medication selection and timing. A quick-reference card was developed to guide staff in preparing RSI medications. The main outcomes were (1) standard selection, defined as administration of indicated medications and avoidance of medications not indicated, and (2) efficient administration, defined as an interval of <30 seconds from sedative to neuromuscular blocker (NMB) infusion.

RESULTS

A total of 253 consecutive patients underwent RSI during 3 consecutive periods: the historical (preimprovement) period (n = 136), the checklist only period (n = 68), and the checklist/card period (n = 49). The rate of standard selection of 3 RSI medications (atropine, lidocaine, and rocuronium) did not improve. The rate of efficient sedative and NMB administration improved from 56% in the historical period to 88% in the checklist period (p = 0.005). The median duration of RSI medication administration decreased from 28 seconds (interquartile range [IQR], 23-44 seconds) in the historical period to 19 seconds (IQR, 15-25 seconds) in the checklist/card period (p = 0.004).

CONCLUSION

In a quality-improvement project in a pediatric ED, a checklist-based intervention improved RSI medication administration technique but not selection.

Emergency Neurological Life Support: Traumatic Spine Injury

Traumatic spine injuries (TSIs) carry significantly high risks of morbidity, mortality, and exorbitant health care costs from associated medical needs following injury. For these reasons, TSI was chosen as an ENLS protocol. This article offers a comprehensive review on the management of spinal column injuries using the best available evidence. Alhough the review focuses primarily on cervical spinal column injuries, thoracolumbar injuries are briefly discussed as well. The initial emergency department clinical evaluation of possible spinal fractures and cord injuries, along with the definitive early management of confirmed injuries, is also covered.

Hyperkalemia: Disorders of Internal and External Potassium Balance

The serum potassium level is normally preserved de spite changes in potassium intake and output (the exter nal potassium balance) and changes in its distribution in the body (the internal potassium balance). External potassium homeostasis depends primarily on renal ex cretion of the daily exogenous potassium burden. Inter nal homeostasis depends on the extrarenal regulation of potassium. Skeletal muscle and liver are the dominant sites of that regulation. The two chief regulators of inter nal balance are insulin and catecholamines, the latter acting through β-adrenergic receptors. Acid-base bal ance and the cellular potassium content are other important regulators of internal balance. The major disorders of external balance are renal failure, hypo reninemic hypoaldosteronism, interstitial nephritis, and a variety of drugs that impair renal potassium excretion. The major disorders of internal balance are diabetes mellitus, acidosis, medications, and release of endoge nous potassium during vigorous exercise, traumatic muscle injury, or tumor lysis chemotherapy. These dis orders frequently result in troublesome elevations of serum potassium in the intensive care setting. Their re view in this article includes a thorough discussion of the evaluation and proper management of the hyperkalemic patient.

Use of Muscle Relaxants in the Intensive Care Unit

Muscle relaxants are now routinely used in intensive care units despite the relative paucity of literature regarding their use, safety, and efficacy in this setting. Although the theory of the pharmacology of muscle relaxants is simple, many clinicians involved in critical care receive little or no formal education about their use either in medical school or during postgraduate training. Proper dosing, careful monitoring, awareness of possible side effects, and adequate sedation facilitate safe use of muscle relaxants in the intensive care unit. Muscle relaxants are not, however, a substitute for sedatives, hypnotics, amnesties, or analgesics and should rarely, if ever, be used without appropriate sedation and analgesia. A wide variety of agents now available with substantial differences in dosing, pharmacology, and side-effect profiles makes clearly delineated indications for use and end points for discontinuation necessary. Using muscle relaxants without monitoring is like using antiarrhythmics without an electrocardiograph.

Major surgical procedures in children with cerebral palsy

There are 3 surgical procedures that patients with cerebral palsy (CP) undergo that may be considered major procedures: femoral osteotomies combined with pelvic osteotomies, spine fusion, and intrathecal baclofen pump implant for the treatment of spasticity. Many complications are known to occur at a higher rate in this population, and some may be avoided with prior awareness of the preoperative pathophysiology of the patient with CP.

An unanticipated difficult airway in Lesch-Nyhan syndrome

An 11-year-old boy with Lesch–Nyhan syndrome presented to the emergency for fixation of a fractured femur. During induction of general anesthesia, unexpected difficult intubation was encountered with a 6.5-mm ID endotracheal tube and successively smaller tubes, also failing to pass 1 cm beyond the vocal cords. Intubation was finally achieved with a 4.5-mm ID tube. The surgery was completed uneventfully. A tracheal diverticulum was found in the computerized tomography (CT) scan performed postoperatively to account for this unexpected difficult intubation. This case highlights the anesthetic concerns in Lesch-Nyhan syndrome and also reports the rare occurrence of a tracheal diverticulum associated with it.

The limits of succinylcholine for critically ill patients

BACKGROUND

Urgent tracheal intubations are common in intensive care units (ICU), and succinylcholine is one of the first-line neuromuscular blocking drugs used in these situations. Critically ill patients could be at high risk of hyperkalemia after receiving succinylcholine because one or more etiologic factors of nicotinic receptor upregulation can be present, but there are few data on its real risk. Our objectives in this study were to determine the factors associated with arterial potassium increase (ΔK) and to assess the occurrence of acute hyperkalemia ≥6.5 mmol/L after succinylcholine injection for intubation in the ICU.

METHODS

In a prospective, observational study, all critically ill patients intubated with succinylcholine in an ICU were screened. Only intubations with arterial blood gases and potassium measurements before and after (K(after)) a succinylcholine injection were studied.

RESULTS

During 18 months, 131 critically ill patients were intubated after receiving succinylcholine with arterial potassium before and after intubation (K(after)) for a total of 153 intubations. After multivariate analysis, the only factor associated with ΔK was the length of ICU stay before intubation (ρ = 0.561, P < 0.001). The factors associated with K(after) ≥6.5 mmol/L (n = 11) were the length of ICU stay (P < 0.001) and the presence of acute cerebral pathology (P = 0.047). The threshold of 16 days was found highly predictive of acute hyperkalemia ≥6.5 with 37% (95% confidence interval: 19%-58%) of K(after) ≥6.5 after the 16th day compared with only 1% (95% confidence interval: 0%-4%) of K(after) ≥6.5 when succinylcholine was injected during the first 16 days.

CONCLUSIONS

This study shows that the risk of ΔK after succinylcholine injection is strongly associated with the length of ICU stay. The risk of acute hyperkalemia ≥6.5 mmol/L is highly significant after 16 days.

Influence of chronic and acute spinal cord injury on skeletal muscle Na+-K+-ATPase and phospholemman expression in humans

Na(+)-K(+)-ATPase is an integral membrane protein crucial for the maintenance of ion homeostasis and skeletal muscle contractibility. Skeletal muscle Na(+)-K(+)-ATPase content displays remarkable plasticity in response to long-term increase in physiological demand, such as exercise training. However, the adaptations in Na(+)-K(+)-ATPase function in response to a suddenly decreased and/or habitually low level of physical activity, especially after a spinal cord injury (SCI), are incompletely known. We tested the hypothesis that skeletal muscle content of Na(+)-K(+)-ATPase and the associated regulatory proteins from the FXYD family is altered in SCI patients in a manner dependent on the severity of the spinal cord lesion and postinjury level of physical activity. Three different groups were studied: 1) six subjects with chronic complete cervical SCI, 2) seven subjects with acute, complete cervical SCI, and 3) six subjects with acute, incomplete cervical SCI. The individuals in groups 2 and 3 were studied at months 1, 3, and 12 postinjury, whereas individuals with chronic SCI were compared with an able-bodied control group. Chronic complete SCI was associated with a marked decrease in [(3)H]ouabain binding site concentration in skeletal muscle as well as reduced protein content of the α(1)-, α(2)-, and β(1)-subunit of the Na(+)-K(+)-ATPase. In line with this finding, expression of the Na(+)-K(+)-ATPase α(1)- and α(2)-subunits progressively decreased during the first year after complete but not after incomplete SCI. The expression of the regulatory protein phospholemman (PLM or FXYD1) was attenuated after complete, but not incomplete, cervical SCI. In contrast, FXYD5 was substantially upregulated in patients with complete SCI. In conclusion, the severity of the spinal cord lesion and the level of postinjury physical activity in patients with SCI are important factors controlling the expression of Na(+)-K(+)-ATPase and its regulatory proteins PLM and FXYD5.

Succinylcholine-induced hyperkalemia in a patient with multiple sclerosis

BACKGROUND

Succinylcholine administration is associated with hyperkalemia in patients with a variety of medical conditions, including many neuromuscular disorders. Nonetheless, there is a paucity of literature describing hyperkalemia after the administration of succinylcholine to patients with multiple sclerosis.

CASE REPORT

This case report describes a 38-year-old woman with multiple sclerosis who developed life-threatening hyperkalemia after the administration of succinylcholine during rapid sequence intubation.

CONCLUSION

This case highlights the potential for iatrogenic hyperkalemia after succinylcholine in patients with neurologic diseases, including multiple sclerosis.

Rocuronium versus succinylcholine in air medical rapid-sequence intubation

BACKGROUND

It is not known how rocuronium compares with succinylcholine in its effect on intubation success during air medical rapid-sequence intubation (RSI).

OBJECTIVE

To examine the impact of succinylcholine use on the odds of successful prehospital intubation.

METHODS

We performed a retrospective analysis of a critical care transport service administrative database containing patient encounters from 2004 to 2008. Rotor transports of patients ≥ 18 years old, requiring airway management (intubation or backup airway: laryngeal mask airway, Combitube, or cricothyrotomy), and receiving either rocuronium or succinylcholine were included in the analysis. Patients receiving both drugs were excluded. Multiple imputation was used to account for records that were missing data elements. A propensity score based on patient and encounter characteristics was calculated to control for the effect of clinical factors on the choice of drug by air medical personnel. Logistic regression was used to assess the impact of succinylcholine use on the odds of first-attempt intubation. Ordinal logistic regression was used to assess the impact of succinylcholine on the number of attempts required to intubate (1, 2, or ≥ 3 or backup airway).

RESULTS

A total of 1,045 patients met the criteria for analysis; 761 (73%) were male, and the median age was 41 years (interquartile range 26-56). Eight hundred seventy-six (84%) were transported from the scene, and 484 (46%) received succinylcholine. Six hundred twelve (59%) were intubated on the first attempt, 322 (31%) required two attempts, 69 required three or more attempts (7%), and 42 required a backup airway (4%). After propensity score adjustment, succinylcholine was associated with a higher incidence of first-attempt intubation (odds ratio 1.4, 95% CI 1.1-1.8), as well as improved odds for requiring fewer attempts to intubate (odds ratio 1.5, 95% CI 1.2-1.9), as compared with rocuronium.

CONCLUSIONS

Rapid-sequence intubation was more successful with fewer attempts in patients intubated by air medical crews with succinylcholine as opposed to rocuronium. Prospective, randomized studies are needed to confirm these findings and to explore the impact of succinylcholine on the outcomes of air medical-transported patients. Key words: airway management; critical care; emergency medical services; neuromuscular blockade; succinylcholine; rocuronium; rapid-sequence intubation; intubation; air medical transport.

The pharmacology of airway management in critical care

This review provides an update on the pharmacology of airway management, emphasizing medications and management strategies widely used in an intensive care unit setting. Induction agents, muscle relaxants, opioids, sedative-hypnotics, and adjunctive agents are reviewed in the context of emergent airway management. Throughout this review, we emphasize the utility of considering a broad set of pharmacologic agents and approaches for airway management of the critically ill patient.

Electrolyte disturbances associated with commonly prescribed medications in the intensive care unit

Electrolyte imbalances are common in critically ill patients. Although multiple disease states typically encountered in the intensive care unit may be responsible for the development of electrolyte disorders, medications may contribute to these disturbances as well. Medications can interfere with the absorption of electrolytes, alter hormonal responses affecting homeostasis, as well as directly impact organ function responsible for maintaining electrolyte balance. The focus on this review is to identify commonly prescribed medications in the intensive care unit and potential electrolyte disturbances that may occur as a result of their use. This review will also discuss the postulated mechanisms associated with these drug-induced disorders. The specific drug-induced electrolyte disorders discussed in this review involve abnormalities in sodium, potassium, calcium, phosphate, and magnesium. Clinicians encountering electrolyte disturbances should be vigilant in monitoring the patient's medications as a potential etiology. Insight into these drug-induced disorders should allow the clinician to provide optimal medical management for the critically ill patient, thus improving overall healthcare outcomes.

Nicotinic acetylcholine receptor gene expression is altered in burn patients

INTRODUCTION

Burn patients have been observed to be more susceptible to the hyperkalemic effect of the depolarizing muscle relaxant succinylcholine. Changes in nicotinic acetylcholine receptor (nAChR) subunit composition may alter electrophysiologic, pharmacologic, and metabolic characteristics of the receptor inducing hyperkalemia on exposure to succinylcholine. No studies have been performed that show the upregulation and/or alteration of nAChR subunit composition in human burn patients. The scarcity of studies performed on humans with burn injury is mainly attributable to the technical and ethical difficulties in obtaining muscle biopsies at different time frames of illness in these acutely injured patients. nAChRs are expressed in oral keratinocytes and are upregulated or altered in smokers. However, no studies have addressed the expression of nAChRs in the oral mucosa of burn patients.

METHODS

Buccal mucosal scrapings were collected from 9 burn patients and 6 control nonburn surgical intensive care unit patients. For burn and control patients, tissues were collected upon presentation (time: 0 hour) and at time points 12, 24, and 48 hours, 1 week, and 2 weeks. Gene expression of the nAChR subunits alpha1, alpha7, gamma, and epsilon were performed using real-time reverse transcriptase polymerase chain reaction.

RESULTS

alpha7 and gamma nAChR genes were significantly upregulated in burn patients, whereas alpha1 and epsilon nAChR genes were minimally affected, showing no significant changes over time.

DISCUSSION

Over the 2 weeks of measurement, an upregulation of the alpha7 and gamma genes occurred in both burn and control patients; however, the proportion of alpha7 and gamma subunit increases was significantly higher in burn patients than in control surgical intensive care unit patients. The relationship between the thermal injury and the observed alteration in gene expression suggests a possible cause/effect relationship. This effect was observed at a site not affected by the burn injury and in nonmuscle tissues, thus emphasizing the systemic nature of the effect caused by the thermal injury. Because gene expression is the basis of protein production, the upregulation of alpha7 and gamma genes might translate into more alpha7 and gamma protein subunits. These proteins can also combine with each other or with other types of subunits (alpha1, beta, epsilon . . .) to form nAChRs with altered electrophysiologic characteristics leading to the observed abnormal clinical outcomes.

CONCLUSION

Thermal injury may infer a systemic effect because upregulation/alteration of nAChRs occurs in nonmuscle tissues distant from the site of injury. The effect of thermal injury on nAChR gene subunits can be studied using a minimally invasive method (buccal mucosal scraping) and a highly sensitive technology (real-time reverse transcriptase polymerase chain reaction) obviating the need for more invasive methods.

A comparative study of intubating conditions of rocuronium bromide and suxamethonium in adult patients

Aim:

Intubating conditions after Suxamethonium, a time tested popular short acting depolarizing neuromuscular blocking agent, and Rocuronium, a recently introduced intermediate acting non depolarizing neuromuscular blocking agent, with Thiopentone as the sole induction agent, were compared in this study.

Materials and Methods:

The patients were divided into two groups, each consisting of 30 patients: group a patient's received Rocuronium bromide, 0.6 mg/kg and group B patients received Suxamethonium chloride 1.5 mg/kg. In both the groups, jaw relaxation and vocal cord relaxation were considered for atraumatic laryngoscopy at 60 seconds or, if needed, at 75 seconds and then at 90 seconds.

Results:

Intubation conditions were rated as excellent in 90% and good in 10% of the patients who received Rocuronium, and excellent in 100% of the patients who received Suxamethonium.

Conclusion:

It is concluded from this study that intubation can be performed under good to excellent conditions at 60–90 seconds after a bolus dose of Rocuronium of 0.6 mg/kg. The result of this study indicates that this new nondepolarizing neuromuscular blocking agent may be considered as a valuable alternative to Suxamethonium for rapid tracheal intubation, i.e., within 60 seconds, even after induction with Thiopentone as the sole anesthetic agent.

Anaesthetic management of post-burn contractures, a recurrent challenge from oil pipeline vandalization in Nigeria: a case report

A 13 year- old girl presented to the department with sternomental contractures as a result of facial burns from kerosene explosion. Difficult airway was envisaged. Over the period of time she developed sub-mental contracture with keloids; and was scheduled for release of contractures and flap closure.Anaesthesia was induced with halothane and 100% oxygen. A size 3 laryngeal mask airway (LMA) was inserted and anaesthesia maintained with oxygen/nitrous oxide/halothane/muscle relaxant technique. The successful placement of LMA at 2(nd )attempt was aided by a surgical incision on the submental contracture. Blood loss was 600 mls and a unit of packed red blood cells was transfused. She made full recovery and was discharged home after 1 month.

Suxamethonium-induced hyperkalaemia 6 weeks after chemoradiotherapy in a patient with rectal carcinoma

Suxamethonium causes an efflux of potassium (K+) ions by depolarizing acetylcholine receptors within the neuromuscular junction and produces a transient, small rise in serum K+ concentration in normal individuals that is usually of little clinical importance. Despite the clear efficacy and relative safety of suxamethonium in many patients, anaesthetists are also very aware that acute, severe hyperkalaemia resulting in important cardiovascular sequelae (e.g. malignant ventricular arrhythmias, cardiac arrest) may also occur with administration of suxamethonium in susceptible patients, including those with skeletal muscle injury or thermal trauma. In the current report, we describe a patient with rectal cancer initially treated with chemoradiotherapy who developed hyperkalaemia after suxamethonium and further discuss the potential factors that contributed to this response.

Hyperkalemia and cardiac arrest following succinylcholine administration in a 16-year-old boy with acute nonlymphoblastic leukemia and sepsis

OBJECTIVES

To report a case of potentially lethal hyperkalemia related to succinylcholine administration.

DESIGN

Case report.

SETTING

A 13-bed pediatric intensive care unit in a tertiary level, university-based children's hospital.

PATIENT

A 16-yr-old boy treated in the intensive care unit due to Klebsiella pneumoniae sepsis, which developed after chemotherapy for nonlymphoblastic leukemia.

INTERVENTIONS

After admission to the intensive care unit, the patient required intubation (uneventful under ketamine and succinylcholine) and mechanical ventilation. On the 15th day of therapy, when his respiratory variables improved significantly, he was extubated. His cardiac rhythm, respiratory rate, arterial blood pressure, and hemoglobin oxygen saturation were continuously monitored. Several hours later, however, he required reintubation due to respiratory insufficiency. For intubation, precurarization with pancuronium, ketamine, propofol, and succinylcholine was used.

MEASUREMENTS AND MAIN RESULTS

Before and immediately after reintubation, serum potassium levels were measured. Two minutes after intubation, premature ventricular contractions, ventricular fibrillation, bradycardia, and finally cardiac arrest were recognized. An increase of serum potassium from 3.19 to 8.64 mmol/L was observed in arterial blood. The patient was immediately resuscitated with chest compressions, intravenous adrenaline, atropine, lidocaine, and sodium bicarbonate. Potassium values normalized within 30 mins. Further treatment in the intensive care unit was uneventful, and the patient was weaned from mechanical ventilation and discharged to a hematology clinic. At present his mental and physical state is satisfactory.

CONCLUSIONS

Succinylcholine may cause dangerous arrhythmias in septic and immobilized children. The alternative nondepolarizing agents should be used in such cases.

Electroconvulsive therapy complicated by life-threatening hyperkalemia in a catatonic patient

Electroconvulsive therapy (ECT) requires brief general anesthesia, and succinylcholine is a depolarizing neuromuscular blocking agent that is frequently used for this procedure. Its use leads to intracellular potassium release into the extracellular space, usually increasing the serum potassium level by 0.5-1 mEq/L, with little clinical significance. However, long-term immobilization has been associated with changes at the neuromuscular junction (up-regulation of nicotinic cholinergic receptors) and subsequent serious hyperkalemia following succinylcholine administration. We report the case of a severely obese patient, immobilized due to her catatonic state, who developed life-threatening ventricular tachycardia after succinylcholine administration for ECT. Resumption of normal physical activity reverses these neuromuscular junctional changes, allowing subsequent safe succinylcholine administration. Current drug development may eliminate the need for succinylcholine use during ECT.

Labor analgesia for the parturient with neurological disease: what does an obstetrician need to know?

Several neurological disorders including multiple sclerosis, myasthenia gravis, epilepsy, spinal cord injury, and subarachnoid hemorrhage are encountered with increasing frequency in pregnant women worldwide. Although there is absence of uniform anesthetic guidelines for pregnant patients with most of these (and other) neurological disorders, and the decision whether or not to administer regional anesthesia is based on an individual risk-to-benefit ratio on a case-by-case basis, few of these disorders contraindicate the use of neuraxial anesthesia. This article attempts to review the specific concerns for administration of labor analgesia posed by multiple sclerosis, myasthenia gravis, epilepsy, paraplegia and subarachnoid hemorrhage.

Hyperkalemia: a review

Potassium is the principal intracellular cation, and maintenance of the distribution of potassium between the intracellular and the extracellular compartments relies on several homeostatic mechanisms. When these mechanisms are perturbed, hypokalemia or hyperkalemia may occur. This review covers hyperkalemia, that is, a serum potassium concentration exceeding 5 mmol/L. The review includes a discussion of potassium homeostasis and the etiologies of hyperkalemia and focuses on the prompt recognition and treatment of hyperkalemia. This disorder should be of major concern to clinicians because of its propensity to cause fatal arrhythmias. Hyperkalemia is easily diagnosed, and rapid and effective treatments are readily available. Unfortunately, treatment of this life-threatening condition is often delayed or insufficiently attentive or aggressive.

Controversies in rapid sequence intubation in children

PURPOSE OF REVIEW

Rapid sequence intubation is the method of choice for intubation of the emergency department patient. The purpose of the present review is to address several controversies pertaining to emergency department rapid sequence intubation of children.

RECENT FINDINGS

The topics covered in this review include the determination of the appropriate clinician to perform emergency department intubation, the use of atropine and lidocaine as premedications, the choice of sedative agents depending upon the clinical scenario, and the choice of neuromuscular blockade agent. Concerning these topics: The literature supports that emergency department physicians, with appropriate training, successfully perform intubation in most patients. Limited data exist to determine the appropriate use of atropine and lidocaine for rapid sequence intubation. Etomidate has clearly become a preferred sedative for rapid sequence intubation with a low risk of cardiovascular side effects. Thiopental and propofol may more readily provide adequate sedation as compared with etomidate but both have the potential to reduce blood pressure. Succinylcholine arguably remains the preferred neuromuscular blockade agent for rapid sequence intubation in most children. The side effects of succinylcholine occur in relatively predictable circumstances. Rocuronium is a commonly used nondepolarizing paralytic agent but its prolonged duration of action must be weighed against the risk of side effects associated with succinylcholine.

SUMMARY

Though more research is needed, the available data allow for the development of protocols that will result in a rational, scenario-based approach to rapid sequence intubation in children.

Na+-K+ pump stimulation restores carbacholine-induced loss of excitability and contractility in rat skeletal muscle

Intense exercise results in increases in intracellular Na+ and extracellular K+ concentrations, leading to depolarization and a loss of muscle excitability and contractility. Here, we use carbacholine to chronically activate the nicotinic acetylcholine (nACh) receptors to mimic the changes in membrane permeability, chemical Na+ and K+ gradients and membrane potential observed during intense exercise. Intact rat soleus muscles were mounted on force transducers and stimulated electrically to evoke short tetani at regular intervals. Carbacholine produced a 2.6-fold increase in Na+ influx that was tetrodotoxin (TTX) insensitive, but abolished by tubocurarine, resulting in a significant 36% increase in intracellular Na+, and 8% decrease in intracellular K+ content. The mid region, near the motor end plate, had much larger alterations than the more distal regions of the muscle, and showed a larger membrane depolarization from -73 +/- 1 to -60 +/- 1 mV compared with -64 +/- 1 mV. Carbacholine (10(-4) M) significantly reduced tetanic force to 31 +/- 3% of controls, which underwent significant recovery upon application of Na+-K+ pump stimulators: salbutamol (10(-5) M), adrenaline (10(-5) M) and calcitonin gene-related peptide (CGRP; 10(-7) M). The force recovery with salbutamol was accompanied by a recovery of intracellular Na+ and K+ contents, and a small but significant 4-5 mV recovery of membrane potential. Similar results were obtained using succinylcholine (10(-4) M), indicating that Na+-K+ pump stimulation may prevent or restore succinylcholine-induced hyperkalaemia. The stimulation of the Na+-K+ pump allows muscle to partially recover contractility by regaining excitability through electrogenically driven repolarization of the muscle membrane.