Prehospital management of acute seizures and status ...

150847-PAO - Folio : p179 - Type : pINT 13-01-09 11:25:55 L : 179.991 - H : 249.992 - Couleur : Black

Prehospital management of acute seizures and status epilepticus Shaun A. Hussain, Jean-Louis Chabernaud

Seizures constitute the chief complaint in approximately 5% of all phone calls made to emergency services operators, and 8% of calls involving children (Michael & O’Connor, 2011). The elevated rate observed in pediatric cases reflects the high incidence of acute seizures among children, and in particular, the observation that age-specific incidence of status epilepticus (SE) in highest in the first year of life (Hesdorffer, et al., 1998; Shinnar et al., 1997). The principal goal of prehospital management is the prevention – and if possible resolution – of prolonged convulsive SE. The patients at greatest risk for SE include children with a history of prolonged febrile seizures, prolonged afebrile seizure (Berg & Shinnar, 2001), and patients with symptomatic epilepsy such as Lennox-Gastaut syndrome (Shinnar et al., 1997). Decision-making during the first 10 minutes of a seizure often proves critical in avoiding dangerously prolonged seizures, i.e. those seizures in excess of 30 minutes which may precipitate irreversible excitotoxic brain injury.

HOME MANAGEMENT OF ACUTE CHILDHOOD SEIZURES Parents, teachers, and other primary caregivers are the first line of defense in the prevention of pediatric SE. It is worth mentioning that specific interventions can be counter-productive and all caregivers should ideally be familiar with basic seizure management. Specifically, caregivers should counseled to (1) remain calm, (2) protect the child’s head and move dangerous objects away from the child, (3) place the child in the decubitus position (recovery position) to avoid aspiration, and (4) avoid introducing any object (i.e. finger) into the patient’s mouth. Of chief importance, caregivers should note the time a seizure begins, and if possible, be able to report suspected triggers (e.g. fever, medication noncompliance), details of semiology – especially asymmetry of movements or gaze – and any postictal phenomena, if present. Drug administration by caregivers is discussed below.

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Acute Seizures in Children in the Emergency Setting

ROLE OF THE EMERGENCY SERVICES OPERATOR For the emergency call operator who mobilizes paramedics or other first responders, the key objectives are to identify a seizure – especially an ongoing seizure – and provide advice for caregivers on the scene for short-term care. Although typical reports might clearly signify a seizure, it may be very difficult to obtain pertinent details in the setting in which caregiver is panicked and preoccupied with the belief that a child is dying (Besag et al., 2005). This is especially true in the case of a child’s first seizure. Seizures typically present with a sudden alteration or loss of consciousness, with or without hypertonia and abnormal rhythmic shaking, lasting 30 seconds to 2 minutes, and most often occur in the context of a fever or history of epilepsy. This is usually followed by a slow recovery of consciousness and often accompanied by irregular breathing. Nevertheless, seizure presentations can be highly varied and a detailed interview is often required to definitively characterize a seizure or other paroxysmal event (Abend & Marsh, 2009) and may not be feasible during a phone conversation with emergency services. If in doubt, emergency responders should be mobilized even in cases in which the nature of a paroxysmal event is not clearly established. In those cases in which a seizure has clearly ended and a child is regaining consciousness, it is important to reassure the caller and discuss the expectation that full recovery of consciousness can be slow, yet progressive. If a seizure occurs in the setting of fever, the operator should counsel the patient to employ appropriate cooling measures (e.g. application of a wet towel to the skin rather than immersion in a bath), and when indicated, administer antipyretics (acetaminophen/paracetamol or ibuprofen). In addition to counseling caregivers and gathering a description of a suspected seizure, it is useful for operators to obtain historical data regarding history of epilepsy, prior seizures, specific medication use, medication compliance, and presence of cardiac disease, with special note as to whether there is any history of cardiac arrhythmia. The ascertainment of this data should be verified and continued by first responders.

ROLE OF THE FIRST RESPONDER The training and therapeutic repertoire of first responders varies greatly across countries and even within a given geographic locale. Nevertheless, the key goals of any first responder are the same. Of paramount importance is stabilization of the patient with specific assessment of the airway, breathing, and circulatory status. Respiratory depression is common during seizures and supplemental oxygen should be administered, with consideration of bag-mask ventilation in cases of cyanosis or inadequate respiratory effort (Michael & O’Connor, 2011). Endotracheal intubation is rarely needed during seizures but should be considered if the airway is at risk. Although securing intravenous access in the field may delay arrival to a hospital (Donovan et al., 1989) intravenous access is very helpful in the setting of refractory SE (Martin-Gill et al., 2009). The triad of hypertension, bradycardia and irregular respirations should signal the possibility of intracranial hypertension and prompt transport to a facility

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Prehospital management of acute seizures and status epilepticus

with neurosurgical support. Furthermore, during stabilization and transport, it is important to screen for treatable causes of seizures including hypoxia and hypoglycemia, as determined by continuous pulse oximetry and point of care blood glucose determination, respectively (Michael & O’Connor, 2011). Concurrently, the first responder should determine as best possible whether a seizure is ongoing as suggested by the presence of continued rhythmic movements, gaze preference, etc., while still considering the possibility of an ongoing nonconvulsive, subtle, or subclinical seizure. Nonconvulsive seizures are most often suspected in unresponsive children in whom a convulsive seizure occurs just prior to the onset of sustained unresponsiveness. The suspicion of an ongoing nonconvulsive seizure or SE mandates transport to a hospital in which definitive screening for subclinical seizures can be made by electroencephalographic monitoring. For a seizure that appears to have terminated based on a resolution of hypertonia or abnormal rhythmic movements, and progressive recovery of consciousness, the child should be observed at the very least. If a patient is known to suffer from epilepsy, no further emergency care may be necessary, if the parent or caregiver is familiar with post-seizure management, is comfortable with the recovery plan, and has access to a physician for appropriate follow-up. With specific regard to febrile seizures, reassuring clinical features include generalized tonicclonic semiology without focality, short duration (< 10 minutes), patient age between 1 and 5 years, and lack of another febrile seizure in the preceding 24 hours. In the event of an ongoing seizure, further management is clearly indicated. The key determinant of more aggressive intervention is the presence or absence of SE. Although definitions of SE vary considerably among practitioners and investigators, a seizure of greater than 5 to 10 minutes duration – either a continuous seizure, or intermittent seizures without interval recovery of consciousness – indicates that a patient either already meets criteria for SE or is likely to progress to SE in the absence of pharmacologic intervention (Shinnar et al., 2001).

PREHOSPITAL TREATMENT OF STATUS EPILEPTICUS Among the options for initial treatment of childhood SE in the prehospital setting, the common denominator among these choices is the early use of benzodiazepines. In the setting of a seizure that lasts greater than 5 minutes, parents, teachers, and other caregivers should be empowered to administer benzodiazepines so as to prevent refractory SE, and its associated sequelae. Whereas intravenous benzodiazepine administration is not feasible at school or in the home, there is strong evidence supporting the efficacy and safety of diazepam administered rectally, or midazolam administered via buccal, intranasal, or intramuscular routes. Although rectal diazepam shortens the duration of SE in children (Allredge et al., 1995) both intranasal midazolam (Fis¸gin et al., 2002) and buccal midazolam (McIntyre et al., 2005) may exhibit modestly superior efficacy and are less frequently associated with apnea than diazepam (Rainbow et al., 2002). Of particular relevance to home- or school-based benzodiazepine administration, the avoidance of rectal administration contributes to greater overall satisfaction among caregivers for the midazolam preparations (Holsti et al., 2010).

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With regard to first responders, the benzodiazepine gold standard is intravenous lorazepam (Appleton et al., 2010), with established superiority over intravenous diazepam (Allredge et al., 2001). An interesting development is the recent observation that an intramuscular preparation (via autoinjector) of midazolam was shown to be at least as safe and effective as intravenous lorazepam (Silbergleit et al., 2012). The use of midazolam via buccal, intranasal, and intramuscular routes is expected to gain in popularity in light of observed efficacy rates and ease of administration. The role of benzodiazepines in the treatment of acute prolonged seizures is further discussed in Chapter 13. Beyond benzodiazepines, phenobarbital, fosphenytoin, valproate, pentobarbital, and propofol are frequently employed in the management of SE in children. Their use, however, is largely confined to hospital-based protocols that address benzodiazepine-refractory SE. The potential roles of more contemporary antiepileptic agents such as levetiracetam and lacosamide have not yet been established in the treatment of acute childhood seizures and SE.

CONCLUSION SE is one of the most common neurological emergencies in children with the potential for significant morbidity and mortality. More generally, acute childhood seizures account for a significant proportion of (1) phone calls to emergency services operators, (2) emergency transports, and (3) pediatric emergency room care. Initial management of seizures begins long before arrival in the emergency room and, to a great extent, successful treatment relies upon primary caregivers acting in the home or school. Two important concepts form the basis for our emphasis on prehospital treatment. First is the observation by Shinnar and colleagues (2001) that the probability of seizures that last beyond 5-10 minutes to terminate without intervention is dramatically decreased. Second is the observation by Goodkin and coworkers (2005; 2007) in a rat model of status epilepticus that the target of benzodiazepines and barbiturates, the GABA(A) receptor, undergoes internalization as the duration of seizures extends, such that the responsivity to these medications decreases with time as seizures continue. Human data supports this concept since the fraction of patients responding to first-line treatment at an urban teaching hospital decreased with the duration of seizures (Lowenstein & Alldredge, 1993). As such, overwhelming doses of benzodiazepines and/or barbiturates may be employed, resulting in respiratory compromise, necessitating intubation of the airway and institution of ventilator support, culminating in an admission to a critical care unit. The easiest way to minimize such an outcome would seem to be early prehospital intervention, using some form of diazepam or midazolam that is designed for a non-oral route with reliably rapid absorption and distribution to the brain. The identification of seizures, and especially SE, is carried out by primary caregivers as well as first responders. Although first responders have more pharmacologic options, greater monitoring capabilities, and more robust resuscitation options at their disposal, both primary caregivers and first responders are capable of initiating benzodiazepine therapy for SE or acute seizures greater than 5 minutes in duration. A lack of early prehospital intervention is associated with poor outcomes, and as such, early treatment of acute seizures is a critical first step in the prevention of dangerously prolonged seizures and pharmacorefractory SE.

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Prehospital management of acute seizures and status epilepticus

To summarize: • Acute seizures and status epiletpicus are very common in children and represent a substantial minority of all calls placed to emergency medical services. • Parents, caregivers, and teachers play an important role in identification and treatment of acute seizures as well as status epiletpicus. • Seizures less than 5 minutes in duration do not usually require acute pharmacologic intervention. • Seizures lasting more than 5 to 10 minutes have a very low probability of spontaneous resolution; seizures longer than 5 minutes are likely to progress to status epilepticus. • Drug treatment should be initiated for seizures lasting longer than 5 minutes. • Rectal diazepam is a reasonable first choice in the effort to abort prolonged seizures, and is widely available in the United States. Where available, buccal, intranasal, and intramuscular formulations of midazolam may confer greater safety and efficacy.

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