Pediatric Post Cardiac Arrest Syndrome (PCAS) Part 2

Welcome to PICU Doc On Call, a podcast dedicated to current and aspiring intensivists. My name is Pradip Kamat. My name is Rahul Damania and we come to you from Children’s Healthcare of Atlanta-Emory University School of Medicine.Today's episode Is part two of our pediatric post-cardiac arrest care syndromeIf you have not yet listened to part one, I would highly encourage you to visit that episode prior to delving into this one.Part 1 addressed the epidemiology, causes, and pathophysiology of POST CARDIAC ARREST SYNDROME.Part 2 Today will discuss management and complications related to post-cardiac arrest syndrome in the ICU.To revisit our index case we had a:11 yo previously healthy M who was admitted to the PICU after cardiac arrest. After stabilization: The patient was taken to head CT which showed diffuse cerebral edema and diffusely diminished grey-white differentiation most pronounced in the basal ganglia. He is now 18-24 hours post-cardiac arrest and the team is dealing with hemodynamic changes, arrhythmias, and difficulty with ventilation. The patient’s neurological exam still remains poor with fixed 5 mm pupils and upper motor neuron signs in the lower extremities.Let’s get right into it:What are some of the principles in management of patients with post cardiac arrest syndrome (PCAS)? Where do we keep the patients blood pressure?Hypotension after ROSC is commonly encountered in children with PCAS. Early hypotension occurred in 27% of children after cardiac arrest is associated with lower survival to hospital discharge and unfavorable neurological outcome. When post-cardiac arrest hypotension is present, it is not clear whether increasing the blood pressure through administration of fluids and inotropes/vasopressors can mitigate harm, despite this 41% of patients under 18 receive vasopressor therapy within the first 6 hours after ROSC. Currently, there is no high-quality evidence to support any single specific strategy for post-cardiac arrest hemodynamic optimization in children. Treatment of post-cardiac arrest hypotension and myocardial dysfunction may be assisted by monitoring and evaluating arterial lactate and central venous oxygen saturation. Parenteral fluids, inotropes, and vasoactive drugs are to be used as needed to maintain a systolic blood pressure greater than the fifth percentile for age. Appropriate vasoactive drug therapies should be tailored to each patient and adjusted as needed.What about cardiac arrhythmia's such as Vtach seen in our patient?The rhythm disturbances observed during the post-cardiac arrest period include premature atrial and ventricular contractions, supraventricular tachycardias, and ventricular tachycardias. Heart block is unusual but can be observed as a manifestation of myocarditis. There is inadequate evidence in adults and no published studies in children to support the routine administration of prophylactic antiarrhythmics after ROSC, but rhythm disturbances during this period may warrant therapy. Treatment depends on the cause and hemodynamic consequences of the arrhythmias. Premature depolarizations, both atrial and ventricular, usually do not require therapy other than maintenance of adequate perfusion and normal fluid and electrolyte balance. Ventricular arrhythmias may signify more serious myocardial dysfunction. QT prolonging agents must be avoided. Many of the vasoactive agents used to support myocardial function can increase myocardial irritability and risk of arrhythmias. Premature atrial or ventricular depolarizations are frequently observed and can be controlled by optimizing the dose of the vasoactive drugs. Bradycardia is frequently seen in TTM and typically requires no therapy. During PCAC, mechanical circulatory support (ECMO) may be considered if significant cardiorespiratory instability persists despite appropriate volume expansion and administration of inotropes, vasopressors, and, if indicated, antiarrhythmics.In a study de Mos N et al (CCM 2006) in a PICU population, the use of ECMO within 24 hours after ROSC was associated with reduced mortality. Case series have documented the role of ECMO88 and ventricular assist device support89,90 in children with refractory cardiogenic shock or acute fulminant myocarditis (Blume Ed et al., J Heart Lung Transplant 2016).What about oxygenation and ventilation strategies in our patient with PCASOptimal oxygenation and ventilation of children after ROSC may be hampered by the pathology that precipitated the cardiac arrest (such as drowning with resultant post-pulmonary edema) and by the ensuing post-cardiac arrest pathophysiology. Further management challenges may be caused by aspiration and lung injury occurring during resuscitation efforts as well as ventilator-induced lung injury. Additionally, use of TTM alters the relationship between arterial oxygen saturation and arterial oxygen tension such that, for a given arterial oxygen saturation, the arterial oxygen tension (Pao2) is lower than that observed when the temperature is normal. Hypothermia also decreases the metabolic rate; thus, carbon dioxide production will be lower at any given minute ventilation.Post–cardiac arrest blood gas abnormalities are common in children, particularly in the first hours after ROSC as seen in our patient case. Published evidence has failed to demonstrate a consistent effect of post-cardiac arrest hyperoxia or hypoxemia on outcome. After ROSC, it is reasonable to aim for normal PaO2 (or the value appropriate for the child’s condition if the child has, for example, cyanotic heart disease) and to use the lowest possible fraction of inspired oxygen, weaning to maintain an oxygen saturation of 94% to 99% as a guideline. Throughout PCAC, hypoxemia must be avoided whenever possible, particularly during oxygen titration. The 2010 AHA PALS guidelines recommended prompt arterial blood gas analysis as soon as possible after ROSC and within 10 to 15 minutes of establishing initial mechanical ventilation to guide oxygen administration and titration and to support mechanical ventilation.Post–cardiac arrest derangements in PaCO2 are common. On the basis of available evidence, after ROSC, it is reasonable to target normocapnia (ie, normal for the child, or PaCO2 35–45 mm Hg) or a PaCO2 specific for the patient’s condition, limiting exposure to severe hypercapnia and hypocapnia. Lung protective strategies such as low TV, high PEEP should be used to minimize VILI.Can you comment on targeted temperature management?Post–cardiac arrest pyrexia (elevated core body temperature) is common, and persistent hyperthermia is associated with unfavorable neurological outcomes in children (Bambea MM PCCM 2010).During PCAC, fever (≥38°C) should be aggressively treated. To treat the child who remains comatose after OHCA, the 2015 AHA PALS guidelines update recommended that it is reasonable either to maintain continuous normothermia (TTM to 36°C–37.5°C) for 5 days or to maintain 2 days of continuous hypothermia (TTM to 32C°–34°C) followed by 3 days of continuous normothermia (TTM to 36°C–37.5°C).2 Because increased mortality was associated with temperatures <32°C, if TTM to 32°C to 34°C is used, meticulous care must be provided to prevent temperatures <32°C.Post–cardiac arrest derangements in PaCO2 are common. On the basis of available evidence, after ROSC, it is reasonable to target normocapnia (ie, normal for the child, or Paco2 35–45 mm Hg) or a Paco2 specific for the patient’s condition, limiting exposure to severe hypercapnia and hypocapnia. Lung protective strategies such as low TV, high PEEP should be used to minimize VILI.What about treatment of seizures in PCAS and can you also comment on sedation , analgesia and the use of NMB in these patients ?Seizures occur in 10% to 50% of children who remain encephalopathic after achieving ROSC. (Abend NS et al Neurology 2009). Furthermore, about half of children with post-ROSC seizures experience exclusively non-convulsive (subclinical, EEG only) seizures, which cannot be identified by clinical observation alone. Seizures could not be predicted from any clinical or resuscitation variables. Seizures were associated with unfavorable gross neurological outcomes at discharge but not with higher mortality. Because seizures increase metabolic demand, can worsen metabolic dysfunction, and can increase intracranial pressure, they can contribute to secondary brain injury.For these reasons, many clinicians aim to treat seizures, although the approach is generally...