Rosen & Barkin's 5-Minute Emergency Medicine Consult (112 page)

• 560.9 Unspecified intestinal obstruction
  
• 560.81 Intestinal or peritoneal adhesions with obstruction (postoperative) (postinfection)
  
• 560.89 Other specified intestinal obstruction
  

BASICS

• Ventricular heart rate <60 beats/ min:
  
  • Sinus bradycardia can be normal variant.
    
  • All other rhythms are pathologic.
    
• May be asymptomatic or have hypotension, altered mental status, fatigue, nausea, syncope.
  
• Treatment varies based on ECG findings and clinical status.
  

• Idiopathic:
  
  • Healthy athletes
    
• Intrinsic cardiac disorders:
  
  • Sinus node dysfunction such as sick sinus syndrome (may alternate with tachycardia)
    
  • Atrioventricular block:
    
  • Junctional or ventricular escape rhythm
    
  • Infiltrative disease:
    
    • Amyloidosis, sarcoidosis, hemochromatosis
      
  • Collagen vascular disease:
    
    • Systemic lupus erythematosus (SLE), scleroderma, rheumatoid arthritis
      
  • Anatomic abnormalities:
    
    • Congenital, postsurgical, post-transplant, postradiation
      
  • Muscular disorders:
    
    • Myotonic muscular dystrophy
      
  • Trauma with myocardial contusion
    
• Extrinsic disorders:
  
  • Cardiac injury and infarction:
    
    • RCA infarction can cause sinus bradycardia.
      
    • LAD infarction can cause high-grade block.
      
  • Acidemia
    
  • Medication and toxin effects:
    
    • β-Blockers, calcium channel blockers, digoxin, clonidine, antiarrhythmics, lithium, organophosphate
      
  • Electrolyte abnormalities:
    
    • Hypo-/hyperkalemia, hypoglycemia, hypo-/hypercalcemia, hypermagnesemia
      
  • Vital sign abnormalities:
    
    • Hypoxia, hypothermia, hypotension, HTN
      
  • Endocrine abnormalities:
    
    • Hypothyroidism
      
  • Infectious disease:
    
    • Lyme disease, Chagas disease, diphtheria, endocarditis, myocarditis
      
  • Neurologic disorders:
    
    • Increased intracranial pressure, increased vagal tone, carotid sinus hypersensitivity, spinal cord injury
      
    • Can be triggered by micturition, defecation, coughing, vomiting, ocular pressure, or other Valsalva maneuvers
      

Hypoxia is the most common etiology in children.

Maternal SLE can result in congenital complete heart block.

DIAGNOSIS

• Often asymptomatic
  
• Lightheadedness, confusion, fatigue, decreased level of consciousness
  
• Dyspnea, cyanosis, pallor
  
• Chest pain/pressure, diaphoresis
  
• Hypotension
  
• Syncope
  
• Hypothermia
  
• Cardiac arrest
  

• Medication changes, especially cardiac
  
• Urine output:
  
  • Hypokalemia with diuretics
    
  • Hyperkalemia with renal failure
    
• Trauma:
  
  • Intracranial injury
    
  • Myocardial contusion
    
• Activity at time of symptom onset:
  
  • Increased vagal tone
    

• Respiratory status
  
• Perfusion status, pulses
  
• Regular vs. irregular cardiac rhythm
  
• Mental status, thorough neuro exam
  
• Body habitus, skin/hair/nails
  
• Temperature
  

• ECG and continuous cardiac monitoring
  
• Pulse oximetry
  
• BP monitoring
  
• Glucose and electrolytes
  

• Serum glucose
  
• Serum electrolytes
  
• BUN and creatinine
  
• Cardiac enzymes
  
• Digoxin level
  
• Thyroid function tests
  
• ANA, RF, other rheumatologic testing
  
• Lyme titers
  
• Iron levels
  

• CXR
  
• CT head if patient has altered mental status
  

EKG:

• Sinus bradycardia:
  
  • P wave before every QRS, QRS after every P wave, usually narrow QRS
    
• Sinoatrial block: Abnormal conduction between sinus node and atrium
  
• Sinus arrest:
  
  • No sinus activity, no P waves
    
• Atrioventricular block: Abnormal conduction between atria and ventricles:
  
  • 1st degree: PR >0.2 sec, every P wave conducts a QRS complex
    
  • 2nd-degree type I, Mobitz I, Wenckebach: Progressive prolongation of PR interval with eventual dropped QRS, grouped beats
    
  • 2nd-degree type II, Mobitz II: Stable PR interval and intermittent dropped QRS, high risk of degeneration into 3rd-degree block
    
  • 3rd-degree, complete heart block: Complete dissociation of atrial and ventricular activity, constant P-P interval and constant R-R interval, but no relation between the 2, unstable rhythm
    
• Junctional rhythm:
  
  • Loss of atrial conduction, AV pacemaker “escapes” at 40–60 bpm
    
  • Retrograde P waves may occur before, during, or after QRS, and QRS can be any duration
    
• Idioventricular rhythm:
  
  • Loss of both SA and AV nodal activity, bundle of His or Purkinje network takes over at 30–40 bpm
    
  • QRS always >0.12 sec
    
  • Preterminal rhythm
    

• Normal variant
  
• Cardiac ischemia
  
• Medication toxicity
  
• Pacemaker malfunction
  
• Hypoxia
  
• Hypothermia
  
• Electrolyte abnormality
  
• Renal failure
  
• Hypothyroidism
  
• Infection
  
• Rheumatologic disease
  
• Neuromuscular disease
  
• Increased intracranial pressure
  
• Myocardial contusion
  

TREATMENT

• Treat the patient, not the heart rate
  
• Oxygen:
  
  • For all patients, especially children
    
• If hypothermic, warm the patient and give magnesium:
  
  • Do NOT pace; move patient gently as rough handling can induce v-fib.
    
• Atropine or epinephrine:
  
  • Only with hypotension or altered mental status
    
  • Often ineffective or harmful in 3rd-degree block
    
• Transcutaneous pacing:
  
  • If other measures ineffective
    

• ABCs
  
• Oxygen therapy
  
• Apply pacing pads and continuous cardiac monitoring
  
• IV access
  

• Asymptomatic bradycardia:
  
  • Monitor while continuing workup
    
• Symptomatic or unstable bradycardia:
  
  • Oxygen
    
  • Atropine:
    
    • Symptomatic sinus bradycardia and symptomatic 1st- and 2nd-degree type I AV blocks
      
    • Usually ineffective for high-grade AV blocks
      
  • Epinephrine
    
  • Transcutaneous pacing
    
  • Transvenous pacing if transcutaneous pacing unsuccessful
    
• Find and treat underlying cause:
  
  • Hypoglycemia:
    
    • D50
      
  • Hypocalcemia:
    
    • Calcium gluconate
      
  • Hypercalcemia:
    
    • NS +/– Lasix
      
  • β-Blocker or calcium channel blocker overdose:
    
    • Glucagon, calcium gluconate, insulin, D50, intralipid emulsion
      
  • Hyperkalemia:
    
    • IV calcium, insulin with D50, albuterol, bicarb if acidotic, Lasix, Kayexalate, dialysis
      
  • Hypokalemia:
    
    • Potassium
      
  • Digoxin toxicity:
    
    • Digibind (Digoxin immune Fab)
      
  • MI:
    
    • ASA, Plavix, heparin, statin, cath lab
      
  • Hypothyroidism:
    
    • Levothyroxine
      
  • Hypothermia:
    
    • Warm O
      ₂
      , warm IVF, Bair Hugger, blankets, warming lights, consider warm bladder and gastric irrigation, cardiopulmonary bypass
      
  • Infection:
    
    • Targeted antibiotics, antivirals, or antifungals
      
  • Myocardial contusion:
    
    • Supportive care
      
  • Increased intracranial pressure:
    
    • Mannitol, neurosurgical consult
      
  • Pacemaker malfunction:
    
    • Interrogate pacemaker, cardiology consult
      
  • Idiopathic:
    
    • Cardiology consult for ICU admission and pacemaker placement
      

• Atropine: 0.5–1 mg (peds: 0.02 mg/kg; min. 0.1 mg) IV q3–5 min; max. 3 mg or 0.04 mg/kg
  
• Calcium gluconate: 1,000 mg (peds: 60 mg/kg) IV q3–5min, max. 3 g
  
• D50: 1–2 amps (peds: D10 or D25 2–4 mL/kg) IV
  
• Digoxin immune Fab: Dose varies with amount of digoxin ingested, average 6 vials (peds: Average dose, 1 vial) IV bolus; see package insert
  
• Epinephrine: 0.1–0.5 mg (peds: 0.01–0.03 μg/kg/min) IV q3–5min; infusion 2–10 μg/min (peds: 0.1–1 μg/kg/min) IV
  
• Glucagon: 3–5 mg (peds: 0.05 mg/kg) IV, can repeat once; infusion 1–5 mg/h (peds: 0.07 mg/kg/h) IV for BB or CCB overdose
  
• Insulin regular: 10 U (peds: 0.1 U/kg) IV × 1 with glucagon for BB or CCB overdose. Higher doses may be appropriate after tox. consult.