Changes of Heart Rate Variability During Ventilator Weaning

doi:10.1378/chest.123.4.1222

Chest

Volume 123, Issue 4, April 2003, Pages 1222-1228

https://doi.org/10.1378/chest.123.4.1222 Get rights and content

Study objectives:

Despite the recognition that ventilator weaning is associated with a change in autonomic nervous system activity, there has not been any report concerning the change of heart rate variability (HRV), a reliable method to detect autonomic nervous system activity, in patients during weaning. The aim of this study was to investigate the change of autonomic nervous system activity during ventilator weaning by HRV analysis.

Design:

Prospective study.

Setting:

A 16-bed medical ICU of a tertiary university hospital.

Patients:

Twenty-four patients receiving mechanical ventilation were included. Twelve patients with successful extubation after a spontaneous breathing trial (SBT) [T-piece trial] were classified as the success group; otherwise, the patients were placed in the failure group.

Interventions:

None.

Measurements and results:

Variables, including the total power (TP), and the high-frequency (HF) and low-frequency (LF) components of HRV, were measured in three phases: assist/control mandatory ventilation, pressure support ventilation (PSV), and SBT. While shifting from PSV to SBT, the HRV components decreased significantly in the failure group (TP, p = 0.025; LF, p = 0.007; HF, p = 0.031), but not in the success group.

Conclusions:

By HRV analysis, reduced HRV and vagal withdrawal of the autonomic nervous system activity are the main changes in patients with weaning failure.

Section snippets

Patients

This prospective, observational study was carried out in a 16-bed medical ICU of a tertiary university hospital from November 2000 to February 2001. Patients enrolled in this study with respiratory failure were intubated and received mechanical ventilation for at least 24 h, met the general weaning criteria (see below), and were ready to undergo their first spontaneous breathing trial (SBT) as determined by a primary care physician. Patients were excluded if they were already, or ready to be,

Demographics

Twenty-four patients were enrolled, with 12 patients in the success group. The general clinical features, including gender, age, mean APACHE II score on hospital admission, duration of mechanical ventilation prior to SBT, reasons for respiratory failure, underlying diseases, and uses of various medications, were similar between both groups (Table 1). Pneumonia was the most common cause of respiratory failure. Both groups were similar in baseline blood gas data prior to study (Table 2).

Traditional Weaning Parameters

Discussion

In this study, we found that there were no significant changes in spectral components of HRV when shifting from ACMV to PSV in all the patients. However, the HRV components (HF, LF, and TP) decreased significantly in the failure group while shifting from PSV to SBT, but not in the success group.

Conclusion

The spectral components, including HF, LF, and TP of HRV, decreased significantly in the failure group during the shift from ACMV, PSV, to SBT. The reduced HF component is consistent with a higher f/Vt ratio, and vagal withdrawal of the autonomic nervous system in patients with weaning failure. The finding of a reduced LF component during weaning does not support the concept of the LF component of HRV as a marker of cardiac sympathetic modulation. The changes of the HRV components may be a

ACKNOWLEDGMENT

The authors thank respiratory therapists Chao-Ling Wu, Chin-Yu Chiu, Jai-Jane Jerng, Shu-Ying Liu, Been-Ying Liu, Chun-Meei Lin, and Yu-Chan Lee, and the nurses in the ICU for their assistance.

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Cited by (45)

Ventilator Weaning and Extubation
2024, Critical Care Clinics
Comment on: “Heart Rate Variability as a Predictor of Mechanical Ventilation Weaning Outcomes”
2023, Current Problems in Cardiology
Heart rate variability as a predictor of mechanical ventilation weaning outcomes
2023, Heart and Lung
Delays in the mechanical ventilation (MV) weaning process increase mortality. The spontaneous breathing test is the gold standard to assess weaning and extubation success, although it has approximately 85% accuracy. Studies have demonstrated a correlation between decreased heart rate variability (HRV) and weaning failure.
To assess the usefulness of HRV as a predictor of MV weaning outcomes.
Cross-sectional analytical study in adults of both sexes on MV in intensive care unit (ICU) stay. Patients were divided into weaning success and failure groups. Clinical data were collected, and HRV records were obtained with a heart rate monitor.
The study included 68 individuals – 91.1% in the weaning success group and 8.9% in the failure group. All HRV indices analyzed in both groups were lower than the reference values. No statistical difference was found in the mean RR interval (RRi), the standard deviation of the NN interval (SDNN), and the square root of the mean squared differences of successive NN intervals (RMSSD) between the groups. The weaning failure group had a significant increase in LF (41 vs. 69.4) and LF/HF ratio (0.685 vs. 2.6) and a significant decrease in HF (58.85 vs. 30.2).
HRV measure with spectral analysis can be a good predictor of MV weaning failure. Integrating this assessment tool in ICU to predict weaning outcomes could provide more precise prognoses and more adequate assistance quality.
Non-contact measurement of heart response reflected in human eye
2018, International Journal of Psychophysiology
Citation Excerpt :
The VLF band is an index of sympathetic activity while the HF band is an index of parasympathetic activity. The LF band is a complex mixture comprised of the sympathetic and parasympathetic efferent and afferent activities, as well as the vascular system resonance (Malik, 1996; Shen et al., 2003; Reyes del Paso et al., 2013; Park et al., 2014). The ECG signals were used to detect the R-peak and then to calculate the RRI.
This study aims to develop a non-contact measurement technique for cardiac response that uses an infrared image of the patient's pupil. The pupil contraction rhythm is related to the autonomic balance and major organs (such as the heart) via a neural pathway. In this study, the response of the heart was determined by analyzing the pupillary rhythm based on the harmonic frequencies between them. Seventy undergraduate volunteers of both genders, (35 females and 35 males), with ages ranging between 20 and 30 years (mean: 24.52 ± 0.64 years) were asked to conduct a simple conversation, perform slight movements, and experience sound stimuli to evoke arousal, relaxation, happiness, sadness, or a neutral mood in this experiment. Electrocardiograms and pupil images were measured and analyzed, and the harmonic frequencies were identified to determine the relational response. The cardiac time (heart rate (HR), beats per minute (BPM), the standard deviation of the normal-to-normal (NN) intervals (SDNN), the mean squared differences in the successive N-N intervals (rMSSD), and the percentage difference between adjacent normal interbeat (R-R) intervals > 50 (pNN50)) and frequency (very low frequency (VLF), low frequency (LF), high frequency (HF), VLF/HF, and LF/HF) parameters were also observed with regard to the effects of the movement, conversation, and physiological state. The cardiac response was stable, showing less significance than the effects of the three conditions. Therefore, multi-cardiac measurements were successfully obtained from a simple, low-cost, non-invasive, and non-contact data acquisition method in this study.
Vagal withdrawal and psychological distress during ventilator weaning and the related outcomes
2017, Journal of Psychosomatic Research
Citation Excerpt :
HRV has also been assessed as a physiological variable related to weaning outcomes [20,21]. Specifically, patients with significantly lower baseline HRVs when receiving MV and a greater reduction in HRVs during a weaning trial or weaning ventilation mode transitions have been found to be at a higher risk for MV weaning failure [18,20]. HRV not only directly links the heart to the central ANS [19], but may also be influenced by patients' emotional responses [22–24].
This study investigated the associations between changes in autonomic nervous system (ANS) function, psychological status during the mechanical ventilation (MV) weaning process, and weaning outcomes.
In this prospective study, we recruited 67 patients receiving MV for > 24 h at a medical center in northern Taiwan. Patients' ANS function, represented by heart rate variability (HRV), the rapid shallow breathing index (RSBI), anxiety, fear, and dyspnea, was repeatedly measured 10 min before and 30 min after undergoing a weaning trial. Forty-nine patients capable of sustaining a 2-h weaning trial were successfully weaned.
Compared with the failed group, the success group showed significantly smaller decreases in high-frequency HRV (HRV-HF) and smaller increases in RSBI (per 10 breaths/min/L), fear, dyspnea, and anxiety in response to the weaning trial (odds ratio [OR] = 2.19, 0.81, 0.69, 0.66, and 0.77, respectively; p < 0.05). Multivariate analyses revealed that low-frequency HRV before weaning (OR = 2.32; 95% confidence interval [CI] = 1.13–4.78, p = 0.02), changes in HRV-HF (OR = 3.33; 95% CI = 1.18–9.44, p = 0.02), and psychological fear during the weaning process (OR = 0.50; 95% CI = 0.27–0.92, p = 0.03) were three independent factors associated with 2-h T-piece weaning success.
ANS responses and psychological distress during weaning were associated with T-piece weaning outcomes and may reflect the need for future studies to utilize these factors to guide weaning processes and examine their impact on outcomes.
Diaphragm ultrasound as a new method to predict extubation outcome in mechanically ventilated patients
2017, Australian Critical Care
To evaluate role of diaphragmatic thickening and excursion, assessed ultrasonographically, in predicting extubation outcome.
Fifty-four patients who successfully passed spontaneous breathing trial (SBT) were enrolled. They were assessed by ultrasound during SBT evaluating diaphragmatic excursion, diaphragmatic thickness (Tdi) at end inspiration, at end expiration and diaphragmatic thickness fraction (DTF%). Simultaneously traditional weaning parameters were recorded. Patients were followed up for 48 h after extubation.
Out of 54 included patients, 14 (25.9%) failed extubation. Diaphragmatic excursion, Tdi at end inspiration, at end expiration and DTF% were significantly higher in the successful group compared to those who failed extubation (p < 0.05). Cutoff values of diaphragmatic measures associated with successful extubation were ≥10.5 mm for diaphragmatic excursion, ≥21 mm for Tdi at end inspiration, ≥10.5 mm for Tdi at end expiration, ≥34.2% for DTF% giving 87.5%, 77.5%, 80% and 90% sensitivity respectively and 71.5%, 86.6%, 50% and 64.3% specificity respectively. Combining diaphragmatic excursion ≥10.5 mm and Tdi at end inspiration ≥21 mm decreased sensitivity to 64.9% but increased specificity to 100%. Rapid shallow breathing index (RSBI) <105 had 90% sensitivity but 18.7% specificity.
Ultrasound evaluation of diaphragmatic excursion and thickness at end inspiration could be a good predictor of extubation outcome in patients who passed SBT. It is recommended to consider the use of these parameters with RSBI consequently to improve extubation outcome.

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Chest

Clinical Investigations in Critical CareChanges of Heart Rate Variability During Ventilator Weaning

Study objectives:

Design:

Setting:

Patients:

Interventions:

Measurements and results:

Conclusions:

Section snippets

Patients

Demographics

Traditional Weaning Parameters

Discussion

Conclusion

ACKNOWLEDGMENT

J Auton Nerv Syst

J Am Coll Cardiol

Am Heart J

J Am Coll Cardiol

Heart rate variability

Ann Intern Med

Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control

Science

Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Heart rate variability: standards of measurement, physiological interpretation, and clinical use

Circulation

Low-frequency spectral power of heart rate variability is not a specific marker of cardiac sympathetic modulation

Anesthesiology

Sympathetic nervous system representation in time and frequency domain indices of heart rate variability

Eur J Appl Physiol

Low-frequency component of the heart rate variability spectrum: a poor marker of sympathetic activity

Am J Physiol

Effects of respiratory interval on vagal modulation of heart rate

Am J Physiol

Influence of respiration on metabolic, hemodynamic, psychometric, and R-R interval power spectral parameters

Am J Physiol

Cardiovascular neural regulation explored in the frequency domain

Circulation

Clinical Investigations in Critical Care
Changes of Heart Rate Variability During Ventilator Weaning