Utica College Sinus Arrhythmia Associated with Normal Respiration Discussion

Question Description

I’m working on a nursing discussion question and need an explanation to help me study.

The rhythm shown in this strip is sinus arrhythmia. Both the atrial and ventricular rates, though identical compared to each other, are irregular. Because the strip is shorter than six seconds, and because there is significant irregularity in the rate, I chose to use the small box method to determine the rate range. In order from left to right the rates measure as follows: 94 bpm, 100 bpm, 60 bpm, 68 bpm, and 75 bpm. This means that the rate range is 60 – 100 bpm. Every P wave has a positive deflection and is smooth and rounded in shape, 2 mm in height, and is just over 0.08 seconds in duration making them normal P waves. The PR interval of each complex is within normal range at 0.16 seconds duration. The QRS complex is also normal at approximately 0.06 seconds duration. The QT interval consistently measures 0.28 seconds in duration, which is considered short. This was measured by counting the small boxes from the beginning of each QRS complex to the end of each T wave. I was unable to use the R-R interval method as these are variable. The ST segment is isoelectric. Finally, the T wave has a positive deflection with a smooth, rounded shape and is 2 mm in height.

Sinus arrhythmia can be respiratory in nature, which is a change in heart rate in response to vagal stimuli from inspiration and expiration (Aehlert, 2018, p. 81, Soos & McComb, 2020, Introduction). This occurs primarily in younger patients (Aehlert, 2018, p. 81). Non-respiratory sinus arrhythmia can be caused by cardiac issues such as heart disease or myocardial infarction or may not be related to the cardiac system at all, such as in the case of increased intracranial pressure or with medications such as digitalis (Aehlert, 2018, p. 81, Soos & McComb, 2020, Nonrespiratory). Nurses need to be aware that though patients with sinus arrhythmia typically do not require treatment, they are still to be assessed and monitored since the development of hemodynamic instability is a possibility, likely due to bradycardia, and will need treatment (Aehlert, 2018, p. 82). If hemodynamic instability due to bradycardia were to occur, the patient would likely be treated with atropine and fluids (Aehlert, 2018, p. 82, Lippincott Advisor, n.d.).


Aehlert, B. (2018). ECGs made easy. Elsevier.

Lippincott Advisor. (n.d.). Bradycardia. https://advisor-lww-com.db24.linccweb.org/lna/document.do?bid=2&did=843597

Soos, M., & McComb, D. (2020). Sinus Arrhythmia. StatPearls.https://www.ncbi.nlm.nih.gov/books/NBK537011/