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Sinus Bradycardia/Tachycardia Including Respiratory Variablity
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Normal adult heart rates are 60 to 100 beats per minute (bpm). See Chap. 8, section on Normal ECG at Age Intervals for discussion of childhood norms. Sinus tachycardia is a rapid heart rate that originates from the sinus node. Diagnostic criteria include normal P-wave morphology (normal for the patient), normal PR intervals (0.12–0.2 s), and a 1-to-1 P wave to QRS relationship. Rate is usually less than 160 except in critically ill patients. Occasionally, sinus tachycardia cannot be confirmed and other rhythm diagnoses must be considered. There are numerous causes, including fever, dehydration, hypoxia, stimulants (ie, coffee, nicotine, and illicit drugs), pulmonary embolism, anemia, anxiety, hyperthyroidism, hypotension/shock, sepsis, and many more.
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ED Care and Disposition
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Sinus tachycardia may be perceived as a fast or “pounding” heartbeat. Usually symptoms are felt if there is underlying cardiac disease. Treating the underlying disorder will typically resolve the tachycardia and success can be gauged by the trend toward a normal rate. Consider airway, breathing, and circulation first; oxygen, fluids, airway intervention, or specific therapy are often required.
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Sinus tachycardia is always 1:1 P wave to QRS conduction.
There is no specific treatment for sinus tachycardia, treat the underlying cause.
If you have trouble identifying P waves in rhythms over 120/minute, consider running the electrocardiogram (ECG) at double speed.
If workup and treatment of suspected sinus tachycardia fail to prove useful, pursue other rhythm diagnoses.
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Sinus bradycardia is a heart rate that is ...