Suxamethonium-induced hyperkalaemia in patients with severe intra-abdominal infections

Emergency Airway Management Outside the Operating Room: Current Evidence and Management Strategies

Emergency airway management outside the operating room (OR) is often associated with an increased risk of airway related, as well as cardiopulmonary, complications which can impact morbidity and mortality. These emergent airways may take place in the intensive care unit (ICU), where patients are critically ill with minimal physiological reserve, or other areas of the hospital where advanced equipment and personnel are often unavailable. As such, emergency airway management outside the OR requires expertise at manipulation of not only the anatomically difficult airway but also the physiologically and situationally difficult airway. Adequate preparation and appropriate use of airway management techniques are important to prevent complications. Judicious utilization of pre- and apneic oxygenation is important as is the choice of medications to facilitate intubation in this at-risk population. Recent study in critically ill patients has shown that postintubation hemodynamic and respiratory compromise is common, independently associated with poor outcomes and can be impacted by the choice of drugs and techniques used. In addition to adequately preparing for a physiologically difficult airway, enhancing the ability to predict an anatomically difficult airway is essential in reducing complication rates. The use of artificial intelligence in the identification of difficult airways has shown promising results and could be of significant advantage in uncooperative patients as well as those with a questionable airway examination. Incorporating this technology and understanding the physiological, anatomical, and logistical challenges may help providers better prepare for managing such precarious airways and lead to successful outcomes. This review discusses the various challenges associated with airway management outside the OR, provides guidance on appropriate preparation, airway management skills, medication use, and highlights the role of a coordinated multidisciplinary approach to out-of-OR airway management.

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.

The kalaemic and neuromuscular effects of succinylcholine in centronuclear myopathy: A pilot investigation in a canine model

BACKGROUND

Myopathies are generally considered to increase the risk for succinylcholine-induced hyperkalaemia and may affect the duration of action of neuromuscular blockers. Centronuclear (myotubular) myopathy (CNM) is congenital and produces various degrees of muscular weakness and associated complications such as respiratory failure. The effects of succinylcholine and the potentially lethal consequences of hyperkalaemia on patients with CNM are unknown due to its rarity. One source of information is the dog, as CNM occurs naturally in dogs. Because of its remarkable similarity with the disease in man, canine CNM can serve as a model to further our knowledge of the effects of succinylcholine.

OBJECTIVES

We examined the kalaemic and neuromuscular effects of succinylcholine in dogs with and without autosomal-recessive CNM.

DESIGN

A prospective, experimental study.

SETTING

Anaesthesiology laboratory, College of Veterinary Medicine, Cornell University, New York, USA.

PATIENTS

Six dogs with autosomal-recessive CNM and six control dogs.

INTERVENTIONS

Dogs received succinylcholine 0.3 mg kg during isoflurane anaesthesia.

MAIN OUTCOME MEASURES

Whole blood potassium concentration was measured 5 min before and after succinylcholine administration. Neuromuscular function was measured with acceleromyography and single twitch stimulation.

RESULTS

All dogs recovered uneventfully from anaesthesia. The increase in potassium concentration [mean (SD)] following succinylcholine was similar between groups: CNM 0.5 (0.4) mmol l and control 0.7 (0.4) mmol l (P = 0.47). Recovery of the single twitch to 25, 75 and 90% was longer in the CNM group (all P < 0.001); 90% recovery took 35.5 (1.18) min for the CNM group and 23.3 (1.68) min for the control group.

CONCLUSION

CNM did not exacerbate the increase in blood potassium that is ordinarily seen with succinylcholine. Recovery from succinylcholine was nearly 50% longer in dogs with CNM. Although our sample size is too small to evaluate the incidence of succinylcholine-induced hyperkalaemia, extrapolation of these findings suggests that increased duration of action should be expected if succinylcholine is given to a patient with autosomal-recessive CNM.

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.

Taking the septic patient to the operating room

The acutely septic patient is a multifaceted challenge for the anesthetist. Unlike most elective surgery patients, acutely septic patients have severe systemic disease before the physiologic insults of anesthesia and surgery. The decision to operate is usually informed by the urgent or emergent need to correct a severe surgical problem and weighed against the higher risks of morbidity and mortality from the procedure itself. The care of the septic patient in the intensive care unit can help guide operating room management. However, the acuity and time course of intraoperative events, including hemorrhage and drug-induced shock states, compel the anesthetist to respond aggressively with therapies that may or may not be strongly substantiated with long-term data in the intensive care unit setting. The anesthesiologist must place considerations concerning short-term survival from the acute insult of surgery ahead of longer-term considerations.

Systemic inflammatory response syndrome increases immobility-induced neuromuscular weakness

OBJECTIVE

Inflammation and immobility are comorbid etiological factors inducing muscle weakness in critically ill patients. This study establishes a rat model to examine the effect of inflammation and immobilization alone and in combination on muscle contraction, histology, and acetylcholine receptor regulation.

DESIGN

Prospective, randomized, experimental study.

SETTING

Animal laboratory of a university hospital.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

To produce systemic inflammation, rats (n = 34) received three consecutive intravenous injections of Corynebacterium parvum on days 0, 4, and 8. Control rats (n = 21) received saline. Both groups were further divided to have one hind limb either immobilized by pinning of knee and ankle joints or sham-immobilized (surgical leg). The contralateral nonsurgical leg of each animal served as control (nonsurgical leg).

MEASUREMENTS AND MAIN RESULTS

After 12 days, body weight and muscle mass were significantly reduced in all C. parvum animals compared with saline-injected rats. Immobilization led to local muscle atrophy. Normalized to muscle mass, tetanic contraction was reduced in the surgical leg after immobilization (7.64 +/- 1.91 N/g) and after inflammation (8.71 +/- 2.0 N/g; both p < .05 vs. sham immobilization and saline injection, 11.03 +/- 2.26 N/g). Histology showed an increase in inflammatory cells in all C. parvum-injected animals. Immobilization in combination with C. parvum injection had an additive effect on inflammation. Acetylcholine receptors were increased in immobilized muscles and in all muscles of C. parvum-injected animals.

CONCLUSIONS

The muscle weakness in critically ill patients can be replicated in our novel rat model. Inflammation and immobilization independently lead to muscle weakness.

Chronic Escherichia coli infection induces muscle wasting without changing acetylcholine receptor numbers

OBJECTIVE

Muscle weakness in septic patients is a serious problem as it complicates and lengthens hospital stays, prolongs rehabilitation and increases costs. We examined the effects of a chronic infection with Escherichia coli on muscle function, muscle mass, and the expression of nicotinic acetylcholine receptors (AChRs).

DESIGN AND SETTING

Prospective, randomized animal study in an animal laboratory, university hospital.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

A catheter was implanted into the external jugular vein of anesthetized rats, and a dose of 3.2x10(8) CFU of E. coli bacteria was injected; the catheter was then sealed and tunneled subcutaneously.

MEASUREMENTS AND RESULTS

Animals injected with E. coli bacteria showed a significant decrease in body and muscle mass over the 14-day experimental period. Neuromuscular function was tested by mechanomyography on days 3, 7, and 14 following injection. Tetanic tension decreased over the time course of sepsis, without effecting tetanic fade. Serum levels of acute-phase protein, alpha1-acid glycoprotein, were increased by day 3, and remained significantly higher until day 14. AChRs were quantitated using 125I-labeled bungarotoxin and revealed no differences between groups.

CONCLUSIONS

Central venous injection of E. coli bacteria induces systemic inflammation evidenced as loss of body weight, muscle mass and increased alpha1-acid glycoprotein levels. The inflammation-induced muscle weakness is due to muscle atrophy and not to upregulated AChRs. This model may prove useful for studying maneuvers to prevent muscle wasting with inflammation.

Anesthetic management of the parturient with fever and infection

Fever is a common clinical problem in labor and delivery suites. It can result from a variety of infectious microorganisms, tissue trauma, malignancy, drug administration, and endocrine and immunologic disorders. Infection is the most common cause of fever, reflecting the effect of pyrogens on the hypothalamus. The diagnosis of infection in pregnancy often raises questions about the safety of regional anesthesia in febrile patients. Despite this concern, and lack of universal guidelines, it has now been well established that the presence of infection and fever in labor does not always contraindicate the administration of regional anesthesia.

Management of the septic patient in the operating room

Sepsis, severe sepsis, and septic shock represent the spectrum of physiological response to a variety of infecting pathogens. Multiple-organ dysfunction may result from widespread activation of inflammatory and antiinflammatory mechanisms. Intensive multiorgan support, effective antibiotic therapy, and eradication of the inciting source remain the cornerstones in the care of septic patients. Perioperative planning and management need to ensure the continuation of such care in addition to providing for the requirements of the given surgical procedure.

[The use of curare-like agents in resuscitation]

OBJECTIVE

To analyse current data on use of neuromuscular blocking agents (NBA) in the intensive therapy unit (ITU) patients and to propose practice guidelines.

DATA SOURCES

We did a Medline search of French and English language articles on NBA administration in ITU patients from 1960 to 1998. Data were also selected from our own collection of articles and books.

STUDY SELECTION

Original articles, clinical cases, letters to the editor and review articles were considered.

DATA EXTRACTION

Data on pharmacology of NBA in the ITU patient were extracted, as well as data on administration patterns and cost.

DATA SYNTHESIS

The indications for myorelaxation in ITU patients include either short term use, as in anaesthesia, or long term administration for facilitation of mechanical ventilation, control of increased intracranial pressure, status epilepticus, tetanus and oxygen demand in case of muscular hyperactivity, diagnostic and therapeutic procedures facilitation. A beneficial effect of NBA on the prognosis of the disease for which these agents have been used is not yet proven. Suxamethonium, because for its short onset time and duration of action, is the agent of choice for endotracheal intubation if myorelaxation is required. Among the benzylisoquinolines, atracurium and besilate of cisatracurium are convenient agents in ITU patients, whereas mivacurium is of no special interest. Among the aminosteroids, pancuronium and vecuronium are the most often used agents in the ITU. Rocuronium has not yet been extensively assessed. Myorelaxants carry risks for morbidity and mortality. The difficulty to assess the neurological status and the level of sedation is a recognised adverse effect. An accidental disconnection from the circuit and the resulting asphyxia is nowadays recognised without delay by the ventilator. NBAs increase the rate of bronchopulmonary infections. Cardiovascular complications include extreme bradycardia or sinus arrest following vecuronium administration, and cardiac arrest after suxamethonium injection mainly in burned or traumatised patients. Conversely to anaesthesia, NBAs do not carry a significant risk for anaphylactic or anaphylactoid complications in the ITU. Tachyphylaxis occurs mainly in burns and other pathologies modifying acetylcholine receptors. Neuromuscular complications include myopathy from steroids, postparalytic syndrome, deconditioning syndrome and intensive care polyneuropathy. Prolonged curarisation after discontinuation of NBA administration has a multifactorial origin and must be differentiated from neuromuscular complications. For prolonged neuromuscular blockade, pancuronium, vecuronium and atracurium are the agents of choice. The association with an adequate sedation is essential. Assessment of depth of neuromuscular blockade is not based on clinical symptoms but on train-of-four (TOF) twitch monitoring. A convenient basic relaxation is usually obtained with the suppression of the two last responses to TOF.

CONCLUSION

The use of NBA in ITU patient should result from a rational decision making procedure, the blockade titrated with a TOF monitor and maintained as superficially and shortly as possible.

Succinylcholine induced hyperkalemia and cardiac arrest death related to an EEG study

Changes in EEGs during cardiac arrest have been described in detail by many authors; however, mortality because of an EEG has never been reported. The authors report the case of a patient who developed cardiac arrest causally related to administration of succinylcholine for reduction of excessive amounts of myogenic artifact during an EEG. This case indicates the need for caution when doing an EEG study in an intensive care unit setting.

Comparison of train-of-four and best clinical assessment during continuous paralysis

Train-of-four (TOF) monitoring is recommended in published guidelines during use of continuous-infusion neuromuscular blocking agents (NMB) in the intensive care unit (ICU). To test that recommendation, dual protocols were established in a medical ICU after intensive nursing education. Paralyzed patients received either TOF monitoring with a goal of three twitches or best clinical assessment while receiving atracurium by continuous infusion. Demographics and mean duration of paralysis of 20 patients in the TOF group were no different than that of the 16 patients in the best clinical assessment group. Although most patients demonstrated atracurium tolerance over time, there was no difference between groups in total mg (+/- SEM) infused (10,460 +/- 2,409 versus 9,201 +/- 3,237) or mean microgram/kg/min (15.2 +/- 1.5 versus 12.0 +/- 1.1). The time to clinical recovery was no different between groups (50 +/- 10 versus 45 +/- 12 min). Two complications occurred in the TOF group, with pulmonary emboli despite prophylaxis and an unrecognized cerebrovascular accident in one patient each. We conclude that careful titration of NMB using clinical bedside markers should remain the standard of care with these drugs.

Neuromuscular relaxation and reversal: an update

Neuromuscular relaxants are commonly used in the provision of general anesthesia for the majority of surgical procedures. After a brief overview of the physiology of the neuromuscular junction, pharmacology of both depolarizing and nondepolarizing muscle relaxants will be discussed. Attention will be given to side effects and factors that influence neuromuscular blockade including reversal agents. This article will provide the PACU nurse with the knowledge necessary to provide safe and effective nursing care.

Septic shock

PURPOSE

Many patients with sepsis require surgery for their management, often on an urgent or emergency basis. Anaesthetists are commonly required to manage patients with sepsis and septic shock in the operating room, past anaesthesia recovery area, and the intensive care unit. Since little has been written in the Anaesthesia literature on sepsis and septic shock, a review of this topic was considered appropriate.

SOURCE

References were obtained from computerized searches on the National Library of Medicine (English language), recent review articles and personal files. PRINCIPLES FINDINGS: Septic shock is a common cause of morbidity and mortality. Its presentation may be subtle or catastrophic. Successful management depends on an understanding of the pathophysiology of the syndrome, allowing rapid, appropriate resuscitation. This often requires aggressive correction of volume deficit, maintenance of adequate perfusion pressure with inotropic and vasopressor therapy, mechanical ventilation and correction of coagulopathy. Appropriate cultures must be taken and antibiotic therapy started, often empirically. Anaesthetic management should include careful haemodynamic monitoring. Anaesthesia induction and maintenance must be tailored to the haemodynamically unstable patient.

CONCLUSIONS

The management of the septic patient in the perioperative period presents a challenge for the anaesthetist. Haemodynamic and respiratory instability should be anticipated. Management requires multisystem intervention and careful anesthetic management.

Adverse effects of depolarising neuromuscular blocking agents. Incidence, prevention and management

Muscle relaxants block neuromuscular transmission, acting at nicotinic acetylcholine receptors of the neuromuscular junction. Suxamethonium (succinylcholine) is a depolarising agent, whereas all other relaxants in clinical use are nondepolarising. The desired neuromuscular block results from the structural similarity of muscle relaxants to acetylcholine, enabling the interaction with receptors at the neuromuscular junction. Adverse effects of suxamethonium are generally related to its agonist mode of action. Autonomic cardiovascular effects may result. Other adverse effects include anaphylactic or anaphylactoid reactions, and histamine release. Various disease states may present specific considerations in the use of muscle relaxants. Although many complications of muscle relaxants (such as prolonged block or resistance) are easily treated, others may require immediate intervention and vigorous therapy. Careful selection of appropriate relaxants for particular patients will usually prevent the occurrence of complications.

Potassium and anaesthesia

Potassium is the principle intracellular ion, and its concentration and gradients greatly influence the electrical activity of excitable membranes. Because anaesthesia is so intimately involved with electrically active cells, potassium concentrations in surgical patients have received considerable attention in diagnostic and therapeutic applications. With the ongoing evolution in the indications for potassium, it is important to review the role of potassium in cellular activity, in storage and regulation, in diseases that alter potassium homeostasis, and in the therapeutic implications of perioperative alterations of potassium concentration. A rational approach to abnormal potassium values and the use of potassium in the operating room is sought, based on a physiological understanding of risks and benefits.

Suxamethonium and hyperkalaemia

Severe life-threatening hyperkalaemia may occur following administration of suxamethonium during certain periods after burns, neurological injuries, and in certain other conditions. Although this response is well-known, there is disagreement about when it may occur. This review describes the normal hyperkalaemic response to suxamethonium, the factors affecting it, the conditions in which it may be exaggerated, and the periods of high risk.

Combined H1 and H2 receptor blockade attenuates the cardiovascular effects of high dose atracurium in rabbits

Large doses of atracurium (1.5 mg/kg) (six times the ED95) have been reported to provide adequate conditions for rapid sequence endotracheal intubation within 60 seconds in humans. However, this dose can result in significant histamine release and systemic hypotension. We therefore studied the efficacy of histamine receptor blockade in attenuating this response. Four groups of five rabbits were pretreated as follows: Group I--control, Group II--H1 blockade (1 mg/kg diphenhydramine), Group III--H2 blockade (cimetidine 4 mg/kg), and Group IV--H1 and H2 blockade (diphenhydramine 1 mg/kg and cimetidine 4 mg/kg). All rabbits were anesthetized and then 1.8 mg/kg (six times the rabbit ED95) atracurium was administered. Group I rabbits experienced a decrease in MAP of 12.2 mmHg after one minute, a change that was significantly greater than Group IV in which MAP decreased by 0.8 mmHg (p less than 0.001). H1 or H2 receptor blockade alone was associated with intermediate changes in MAP not significantly different from control. We conclude that combined H1 and H2 receptor blockade attenuates the cardiovascular effects associated with large doses of atracurium in the rabbit and that this combination of antagonist drugs might have similar effectiveness in humans.