Related Experiment Video
Updated: Aug 11, 2026

Drug-Induced Sleep Endoscopy (DISE) with Target Controlled Infusion (TCI) and Bispectral Analysis in Obstructive Sleep Apnea
Published on: December 6, 2016
Respiratory sinus arrhythmia: an index of light anaesthesia
C J Pomfrett1, J R Barrie, T E Healy
1University Department of Anaesthesia, Withington Hospital, Manchester.
Abstract:
This study was designed to test if changes in the degree of respiratory sinus arrhythmia (RSA) can be used as an index of light anaesthesia. An on-line, real-time data logging system was used to record simultaneously the EEG and ECG waveforms from 10 patients undergoing routine surgery using i.v. propofol (Diprivan) anaesthesia. The degree of RSA was determined in real-time. The median frequency of the EEG was derived off-line and correlated with the degree of RSA. Time series analysis was performed on the derived indices off-line. Significant changes in the degree of RSA occurred in response to changes in propofol infusion in all patients; these changes corresponded also to changes in the median frequency of the EEG. Heart rate and ventilatory frequency are measured routinely during surgery and it is suggested that on-line monitoring of RSA, derived from these standard signals, provides a more convenient and objective index of lightening anaesthesia than either EEG analysis or classical estimates of anaesthetic depth based on arterial pressure or heart rate.
Related Concept Videos
Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
Respiratory Volumes and Capacities I
Special considerations while measuring oxygen saturation
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
Physical Assessment of the Respiratory Tract II: Inspection
Chest Configuration
The chest configuration can...
ECG Interpretation of Arrhythmias I: Sinus Arrhythmias
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...

