Rosen & Barkin's 5-Minute Emergency Medicine Consult (43 page)

• Glucose
  
• Ionized calcium
  
• Magnesium level
  
• Urine pregnancy
  
• Additional labs to evaluate underlying cause:
  
  • CBC, blood cultures for sepsis
    
  • LFT for hepatic failure
    
  • Aspirin level
    
  • Urine toxicology screen
    
  • Urine diuretics screen (bulimia)
    
  • Urine diuretic screen (surreptitious diuretic abuse)
    
  • Renin level
    
  • Cortisol level
    
  • Aldosterone level
    
  • TSH, T4
    
  • D
    -dimer
    

CXR:

• May identify cardiomyopathy or CHF
  
• Underlying pneumonia
  

ECG:

• May identify regional wall motion abnormalities or valvular dysfunction
  
• Evaluate for conduction disturbances.
  

• Respiratory alkalosis:
  
  • It is essential to rule out organic disease prior to diagnosing hyperventilation syndrome or anxiety states.
    
• Metabolic alkalosis:
  
  • Saline responsive (urine Cl
    ⁻
    <20 mEq/dL):
    
    • Loss of gastric secretions
      
    • Chloride-losing diarrhea
      
    • Diuretics
      
    • Post (chronic) hypercapnia
      
    • CF
      
  • Saline resistant:
    
    • Hyperaldosteronism
      
    • Cushing syndrome
      
    • Bartter syndrome
      
    • Exogenous mineralocorticoids or glucocorticoids
      
    • Gitelman syndrome
      
    • Hypokalemia
      
    • Hypomagnesemia
      
    • Milk–alkali syndrome
      
    • Exogenous alkali infusion/ingestion
      
    • Blood transfusions
      

TREATMENT

Airway, breathing, circulation (ABCs):

• Early intubation and airway control for altered mental status
  
• IV, oxygen, and cardiac monitor
  
• Naloxone, D
  ₅₀
  W (or Accu-Chek), and thiamine for altered mental status
  

• Respiratory alkalosis:
  
  • Treat underlying disorder.
    
  • Rarely life threatening
    
  • Sedation/anxiolytics for anxiety, psychosis, or drug overdose
    
  • Rebreathing mask bag for hyperventilation syndrome (used cautiously)
    
• Metabolic alkalosis: Examination of the urine chloride allows etiologies to be divided into saline-responsive or saline-resistant causes:
  
  • Urine chloride <20 mEq/L indicates volume depletion:
    
    • Rehydration with 0.9% saline lowers serum HCO
      ₃
      ⁻
      by increasing renal HCO
      ₃
      ⁻
      excretion
      
    • Saline-responsive causes are associated with volume depletion.
      
  • Urine chloride >20 mEq/L indicates saline-resistant etiology. Treat underlying disorder:
    
    • Potassium supplementation in hypokalemic states
      
    • Antagonism of aldosterone with spironolactone
      
    • Acetazolamide to increase renal HCO
      ₃
      ⁻
      excretion in edematous states
      
  • Other:
    
    • Infusion of dilute HCl in severe cases of metabolic alkalosis
      
    • Antiemetics for vomiting
      
    • Proton pump inhibitors for patients with NG suction
      
    • Follow ventilatory status closely.
      
    • Correct electrolyte abnormalities.
      
    • Consider hemodialysis for severe electrolyte abnormalities.
      

• Dextrose: D
  ₅₀
  W 1 amp (50 mL or 25 g; peds: 2% dextrose and water 2–4 mL/kg) IV
  
• KCl (K-Dur, Gen-K, Klor-Con): 20–120 mEq PO daily
  
• Naloxone: 2 mg (peds: 0.1 mg/kg) IV or IM initial dose
  
• Thiamine (vitamin B
  ₁
  ): 100 mg (peds: 50 mg) IV or IM
  
• 0.1–0.2 N HCl (100–200 mEq/L): Infuse over 24–48 hr at a rate not faster than 0.2 mmol/kg/h and through a central line to prevent sclerosing vein
  

FOLLOW-UP

• ICU admission if:
  
  • pH >7.55 or altered mental status
    
  • Dysrhythmias
    
  • Severe electrolyte abnormalities
    
  • Hemodynamic instability
    
• Coexisting medical illness requiring admission
  

Resolving or resolved alkalosis

• Increased minute ventilation is the primary cause of respiratory alkalosis, characterized by decreased PaCO
  ₂
  and increased pH.
  
  • Metabolic alkalosis is usually caused by an increase in HCO
    ₃
    ⁻
    , reabsorption secondary to volume, potassium, or Cl
    ⁻
    loss.
    
  • Contraction alkalosis can result from extracellular volume reduction, with a consequent increase in the plasma HCO
    ₃
    ⁻
    concentration.
    
  • Clues to the presence of a mixed acid–base disorder are normal pH with abnormal PCO
    ₂
    or HCO
    ₃
    ⁻
    , when the HCO
    ₃
    ⁻
    and PCO
    ₂
    move in opposite directions, or when the pH changes in the direction opposite that expected from a known primary disorder.
    

• Ayers C, Dixon P. Simple acid-base tutorial.
  J Parenter Enteral Nutr
  . 2012;36(1):18–23.
  
• Khanna A, Kurtzman NA. Metabolic alkalosis.
  J Nephrol
  . 2006;(suppl 9):S86–S96.
  
• Laski ME, Sabatini S. Metabolic alkalosis, bedside and bench.
  Semin Nephrol
  . 2006;26(6):404–421.
  
• Middleton P, Kely AM, Brown J, et al. Agreement between arterial and central venous values of pH, bicarbonate, base excess and lactate.
  Emerg Med J.
  2006;23(8):622–624.
  
• Robinson MT, Heffner AC. Acid base disorders. In: Adams J, ed.
  Emergency Medicine
  . Philadelphia, PA: Elsevier; 2012.
  

See Also (Topic, Algorithm, Electronic Media Element)

CODES

• 276.3 Alkalosis
  
• 276.4 Mixed acid-base balance disorder
  

BASICS

• Dysfunction in either the reticular activating system in the upper brainstem or a large area of 1 or both cerebral hemispheres
  
• Definitions:
  
  • Confusion: A behavioral state of reduced mental clarity, coherence, comprehension, and reasoning
    
  • Drowsiness: The patient cannot be easily aroused by touch or noise and cannot maintain alertness for some time.
    
  • Lethargy: Depressed mental status in which the patient may appear wakeful but has depressed awareness of self and environment globally; cannot be aroused to full function
    
  • Stupor: The patient can be awakened only by vigorous stimuli, and an effort to avoid uncomfortable or aggravating stimulation is displayed.
    
  • Coma: The patient cannot be aroused by stimulation and no purposeful attempt is made to avoid painful stimuli.
    
  • Delirium: Acute onset of fluctuating cognition with impaired attention and consciousness, ranging from confusion to stupor.
    

• Hypoxic:
  
  • Severe pulmonary disease
    
  • Anemia
    
  • Shock
    
  • Intracardiac shunting (especially in pediatrics)
    
• Metabolic:
  
  • Hypoglycemia; hyperglycemia
    
  • Diabetic ketoacidosis
    
  • Nonketotic hyperosmolar coma
    
  • Hyponatremia; hypernatremia
    
  • Hypocalcemia; hypercalcemia
    
  • Hypomagnesemia; hypermagnesemia
    
  • Hypophosphatemia
    
  • Acidosis; alkalosis
    
  • Dehydration
    
  • Deficiency: Thiamine, folic acid, B
    ₁₂
    , niacin
    
  • Hyperammonemia (hepatic encephalopathy)
    
  • Uremia (renal failure)
    
  • CO
    ₂
    narcosis
    
• Toxicologic:
  
  • Toxic alcohols
    
  • Salicylates
    
  • Sedatives and narcotics
    
  • γ-hydroxybutyrate (GHB)
    
  • Anticonvulsants
    
  • Psychotropics
    
  • Isoniazid
    
  • Heavy metals
    
  • Carbon monoxide
    
  • Cyanide
    
  • Toxic plants (jimsonweed, mushrooms, etc.)
    
  • Sympathomimetics
    
  • Anticholinergic, cholinergic
    
  • Antiemetics
    
  • Antiparkinsonian medications
    
  • Withdrawal (especially alcohol, sedatives)
    
• Infectious:
  
  • UTI (especially in elderly)
    
  • Pneumonia
    
  • Sepsis; bacteremia
    
  • Meningitis, encephalitis, brain abscess
    
• Endocrine:;
  
  • Myxedema coma
    
  • Thyrotoxicosis
    
  • Hypothyroidism
    
  • Addison disease
    
  • Cushing disease
    
  • Pheochromocytoma
    
  • Hyperparathyroidism
    
• Environmental:
  
  • Hypothermia
    
  • Hyperthermia; heat stroke
    
  • High-altitude cerebral edema
    
  • Neuroleptic malignant syndrome
    
  • Malignant hyperthermia
    
• Vascular:
  
  • Hypertensive encephalopathy
    
  • Cerebral vasculitis
    
  • TTP, DIC, hyperviscosity
    
  • MI
    
• Primary neurologic:
  
  • Seizures, nonconvulsive status epilepticus, and postictal state
    
  • Head trauma, concussion
    
  • Diffuse axonal injury
    
  • Structural brain lesions:
    
    • Hemorrhage (subdural, epidural, subarachnoid, intraparenchymal)
      
    • Infarction
      
    • Tumors
      
    • Demyelination disorders
      
  • Intracranial hypertension (pseudotumor)
    
  • HIV-related encephalopathy
    
  • Autoimmune/inflammatory encephalitis
    
  • Carcinoid meningitis
    
  • Primary neuronal or glial disorders:
    
    • Creutzfeldt–Jakob disease
      
    • Marchiafava–Bignami disease
      
    • Adrenoleukodystrophy
      
    • Gliomatosis cerebri
      
    • Progressive multifocal leukoencephalopathy
      
• Trauma; burns
  
• Porphyria
  
• Psychiatric
  
• Multifactorial (especially in elderly)