respiratory effort may be compromised by decreased mental status and may result in hypoxia and/or hypercarbia The former may be readily measured using pulse oximetry, although values will be inaccurate if a toxic hemoglobinopathy, such as methemoglobinemia or carboxyhemoglobinemia, is present The adequacy of ventilation can be assessed clinically with a stethoscope and can be quantified by continuously monitoring end-tidal CO2 (see Chapter 21 Cyanosis ) Arterial blood gas analysis with co-oximetry is useful to quantify respiratory and acid–base status and to identify altered hemoglobin states The numerical definition of hypotension varies with age, but pallor and evidence of poor peripheral perfusion, with prolonged capillary refill time, is recognizable even before placement of a sphygmomanometer cuff Immediate administration of IV crystalloid therapy starting with 20 mL/kg of normal saline or lactated Ringer solution is indicated, followed by additional boluses and vasopressors if needed Of the empiric antidotal therapies often used in adults, only glucose (0.25 to 0.5 g/kg) is routinely administered to children An empiric trial of naloxone (0.1 mg/kg, max mg/dose) is sometimes justified, whereas flumazenil and thiamine are given only for specific indications (see Chapter 102 Toxicologic Emergencies ) Severe hypertension is less easily discerned on physical examination If confirmed in more than one extremity, antihypertensives should be administered via the IV route (see Chapters 37 Hypertension and 100 Renal and Electrolyte Emergencies ) Mental status should improve after blood pressure is lowered to high normal levels Patients in hypertensive crises are at risk for hemorrhagic stroke and should be evaluated with a head CT scan if they are neurologically abnormal after blood pressure lowering Hypertension in the comatose patient after traumatic injury may represent a physiologic response to increased ICP to allow maintenance of cerebral perfusion pressure by raising mean arterial pressure In this context, elevated blood pressure should not be lowered with antihypertensives; treatment instead should be aimed at decreasing ICP Hypothermia and hyperthermia are readily recognized once a core (rectal) temperature less than 35°C or greater than 41°C is obtained The mental status of these patients should begin to improve as body temperature approaches the normal range A significant percentage of patients with abnormal core temperatures have drowned, fallen through ice, or were engaged in sporting activities in extreme environments or without adequate hydration Adolescents with hypothermia may have associated ethanol toxicity Head trauma, hypoxia, and/or cervical spine injury may be present in these patients