Pediatric emergency medicine trisk 0289 0289

brain) and displays a number (rSO2 ) that varies with local oxygen delivery and
extraction. A decrease in NIRS rSO2 has been correlated with a fall in local tissue
perfusion in animal models of shock, decreased cardiac output in infants
following cardiac surgery, and predicted fluid responsiveness in dehydrated
children.

FLUID-REFRACTORY AND CATECHOLAMINE-RESISTANT
SHOCK
Fluid-refractory, catecholamine-resistant shock is the persistence of insufficient
tissue perfusion despite at least 60 mL/kg of fluid resuscitation and epinephrine or
norepinephrine ≥1 μg/kg/min. Such patients are at risk for worse outcomes than
those who respond to fluid and/or low-dose vasoactive support. The European
Society of Paediatric and Neonatal Intensive Care validated a modified definition
of refractory septic shock as high vasoactive support, myocardial dysfunction,
and arterial lactate >8 mmol/L, which portended a mortality of 60.3% compared
to only 2.2% without these features. Principles of management for children with
refractory shock include treatment of reversible etiologies, combination
vasoactive drug therapy, reducing metabolic demand through mechanical
ventilation, stress-dose corticosteroid therapy for patients with absolute adrenal
insufficiency, and extracorporeal membrane oxygenation (ECMO) support. In
addition, there is increasing interest in the potential of adjunctive metabolic
therapies, such as thiamine and vitamin C, to treat refractory shock, although at
this point, these remain investigational therapies.
Reversible Etiologies. Treatment of reversible etiologies includes relieving
causes of obstructive shock (tamponade, pneumothorax), prostaglandins for a
closing ductus arteriosus, controlling hemorrhage (often requires surgical
intervention), relieving intra-abdominal hypertension through drainage of ascites
or surgery, and specific therapy for anaphylaxis. Identification and removal of an
infectious source (e.g., infected catheter, empyema, abdominal abscess) may also
enhance resuscitative efforts in septic shock.
Mechanical Ventilation. Sedation and endotracheal intubation reduce the

work of breathing which can divert cardiac output away from the muscles of
respiration and improve perfusion to other organs. Of the sedative agents
available for intubation, ketamine is generally preferred due to its favorable
hemodynamic effects that typically augment cardiac output and blood pressure.
As several studies have reported adverse outcomes following intubation with
etomidate, pediatric septic shock guidelines now recommend against using
etomidate in these patients.