Nocturnal pulse wave attenuation is associated with office blood pressure in a population based cohort

Finger pulse plethysmography predicts gestational hypertension, preeclampsia and gestational diabetes

BACKGROUND

Pregnancy complications related to hypertension can affect both mother and newborn. Pulse wave attenuation (PWA) captured through fingertip photoplethysmography (PPG) provide valuable insights into maternal acute hemodynamic and autonomic vascular function. Here, we quantify the nocturnal dynamics of PWA during early pregnancy and assess their association with the development of gestational hypertension, preeclampsia and gestational diabetes.

METHODS

PWA dynamics were assessed on overnight polysomnography-derived PPG signals from a cohort of 2714 pregnant women (mean age: 26.8 ± 5.5 years) enrolled in the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b). We determined the average duration (PWA duration ) and depth (PWA depth ) of PWA events in all women.

RESULTS

Odds ratio (OR) analysis-adjusted common confounders indicates that an average PWA duration greater than 8.74 s was associated with the increased risk of gestational hypertension [OR = 1.75 (1.27-2.39), P  < 0.001]. Similarly, average PWA depth greater than 1.19 was associated with an increased risk of preeclampsia [OR = 1.53 (1.01-2.33), P  = 0.045] and gestational diabetes [OR = 1.66 (1.01-2.73), P  = 0.044].

CONCLUSION

PWA attenuation dynamics during early pregnancy predict the risk of developing gestational hypertension and diabetes condition for women in their later trimesters. Potentially obtainable from smart wearable consumer devices, PWA analysis offers a low-cost, accessible and scalable marker that can enhance the management of pregnancy-induced cardiometabolic issues.

COVID-19-Induced Changes in Photoplethysmography

INTRODUCTION

Photoplethysmography (PPG) is the science behind many commonly used medical devices such as the pulse oximeter. PPG changes, herein as "PPG dropouts," have been described in existing in vitro studies following artificially induced clot activation. Because COVID-19 causes increased arterial, venous, and microvascular clot formation, our hypothesis is that PPG dropouts identified in vitro can also be found in vivo in patients with COVID-19. The aim of this study is to evaluate PPG recordings and D-dimer levels for patients hospitalized with COVID-19 and compare them with the PPG tracings from non-COVID controls.

MATERIALS AND METHODS

PPG recordings were obtained for 197 ICU patients with COVID-19 and 300 non-COVID controls. PPG tracings were obtained using a TigerTech CovidPlus monitor, which received U.S. FDA emergency use authorization in March 2020 for monitoring the biometrics of patients with COVID-19 and featured unfiltered red and infrared spectrum PPG monitoring. D-dimer lab results were also recorded whenever available.

RESULTS

The results demonstrated significant differences in the prevalence rate of PPG dropout among patients with COVID-19 vs. non-COVID controls. The median PPG dropout rate was 0.58 for COVID-19 patients (median 0.58, IQR 0.42-0.72, P < .05) as opposed to a median 0.0 for non-COVID patients (median 0.0, IQR 0.0-0.0, P < .05). Furthermore, at least one incidence of PPG dropout was detected in 100% of COVID-19 patients, as opposed to 2.3% of non-COVID controls (P < .05). PPG dropout also correlated closely with the normalized serum D-dimer levels taken on the same day. The change in the normalized D-dimer levels was plotted against the change in PPG dropout, and a line of best fit was created. Linear regression resulted in R2 = 0.743 (P < .05), indicating that changes in the PPG dropout rate correlate with hemorheological changes in COVID-19 patients.

CONCLUSIONS

PPG dropout, like D-dimer, may not be specific for COVID-19. However, the inflammatory nature of the disease and the prevalence of prolonged ICU created a large sample size and allowed the authors to observe PPG changes in vivo in a statistically meaningful way. Further confirmatory studies are needed to confirm the potential application of PPG dropout as a measure of inflammation in other disease processes.

Beyond the AHI-pulse wave analysis during sleep for recognition of cardiovascular risk in sleep apnea patients

Recent evidence supports the use of pulse wave analysis during sleep for assessing functional aspects of the cardiovascular system. The current study compared the influence of pulse wave and sleep study-derived parameters on cardiovascular risk assessment. In a multi-centric study design, 358 sleep apnea patients (age 55 ± 13 years, 64% male, body mass index 30 ± 6 kg m^-2 , apnea-hypopnea index 13 [5-26] events per hr) underwent a standard overnight sleep recording. A novel cardiac risk index was computed based on pulse wave signals derived from pulse oximetry, reflecting vascular stiffness, cardiac variability, vascular autonomic tone and nocturnal hypoxia. Cardiovascular risk was determined using the ESC/ESH cardiovascular risk matrix, and categorized to high/low added cardiovascular risk. Comparisons between cardiac risk index and sleep parameters were performed for cardiovascular risk prediction. Apnea-hypopnea index, oxygen desaturation index and cardiac risk index were associated with high cardiovascular risk after adjustment for confounders (p = .002, .001, < .001, respectively). In a nested reference model consisting of age, gender and body mass index, adding cardiac risk index but not apnea-hypopnea index or oxygen desaturation index significantly increased the area under the receiver operating characteristic curve (p = .012, .22 and .16, respectively). In a direct comparison of oxygen desaturation index and cardiac risk index, only the novel risk index had an independent effect on cardiovascular risk prediction (p_CRI  < .001, p_ODI  = .71). These results emphasize the association between nocturnal pulse wave and overall cardiovascular risk determined by an established risk matrix. Thus, pulse wave analysis during sleep provides a powerful approach for cardiovascular risk assessment in addition to conventional sleep study parameters.

Pulse wave amplitude drops during sleep: clinical significance and characteristics in a general population sample

Study Objectives

To explore the clinical significance of pulse wave amplitude (PWA)-drops during sleep as a biomarker for cardiometabolic disorders and describe their main characteristics in a general population sample.

Methods

Cross-sectional study of HypnoLaus cohort, in which 2162 individuals underwent clinical assessment and in-home full polysomnography. PWA-drops were derived from photoplethysmography and processed using a validated automated algorithm. Associations between PWA-drop features (index, mean duration, and mean area under the curve [AUC]) with hypertension, diabetes, and previous cardiovascular (CV) event were analyzed using multivariable-adjusted logistic regression.

Results

Two thousand one hundred forty-nine participants (59 ± 11 years, 51% women, 9.9% diabetes, 41.3% hypertension, 4.4% CV event) were included. Mean ± standard deviation (SD) of PWA-drop index, duration, and AUC during sleep were 51.0 ± 20.3 events/hour, 14.0 ± 2.7 seconds, and 527±115 %seconds, respectively. PWA-drop index was lower in women and decreased with age, while its mean duration and AUC increased in men and elderly. Overall, lower PWA-drop index, longer duration and greater AUC were associated with increased odds of hypertension, diabetes, or CV event after adjustment for confounders. Participants in the lowest quartile of mean duration-normalized PWA-drop index had a significantly higher odds ratio (OR) of hypertension (OR = 1.60 [1.19–2.16]), CV event (OR = 3.26 [1.33–8.03]), and diabetes (OR = 1.71 [1.06–2.76]) compared to those in the highest quartile. Similar results were observed for mean AUC-normalized PWA-drop index regarding hypertension (OR = 1.59 [1.19–2.13]), CV event (OR = 2.45 [1.14–5.26]) and diabetes (OR = 1.76 [1.10–2.83]).

Conclusions

PWA-drop features during sleep seem to be an interesting biomarker independently associated with cardiometabolic outcomes in the general population.

The cardiovascular risk in paediatrics: the paradigm of the obstructive sleep apnoea syndrome

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) describes a spectrum of abnormal breathing patterns during sleep characterised by snoring, increased upper airway resistance and pharyngeal collapsibility, with alteration of normal oxygenation and ventilation. Intermittent desaturations during sleep have multi-organ implications. Adults with OSAS have an increased risk of developing a dysfunctional endothelium that is characterised by greater adherence of inflammatory mediators to endothelial cells and hypercoagulability. There is increasing evidence to show that risk factors for comorbid cardiovascular disease (CVD) can develop during childhood and adolescence and are likely to continue over time. Risk factors for CVD include both modifiable factors and factors that cannot be changed.

MATERIALS AND METHODS

Using the MEDLINE^® electronic database, we reviewed the scientific literature for published studies evaluating the association between sleep-disordered breathing and cardiovascular damage in children.

RESULTS

In this review, we show the role of blood markers in demonstrating the inflammation caused by intermitted oxygen desaturations during sleep in both healthy and obese children. Several instrumental techniques, in addition to serum biomarkers, can be used to assess vascular endothelial damage and its deterioration in the form of a pre-atherosclerotic condition. The confirmation of their role as markers of inflammation and vascular damage is supported by normalisation after resolution or improvement of the sleep-disordered breathing with surgery.

DISCUSSION

Great attention should be given to this condition in infants and children as it will significantly affect their present and future well-being as they grow into adulthood. Healthcare professionals, especially paediatricians, should be trained to recognise the signs and symptoms of the disease in order to send children forward for specialist care in centres dealing with sleep-disordered breathing.

Nasal high flow, but not supplemental O2, reduces peripheral vascular sympathetic activity during sleep in COPD patients

Introduction

Patients with COPD have increased respiratory loads and altered blood gases, both of which affect vascular function and sympathetic activity. Sleep, particularly rapid eye movement (REM) sleep, is known to exacerbate hypoxia and respiratory loads. Therefore, we hypothesize that nasal high flow (NHF), which lowers ventilatory loads, reduces sympathetic activity during sleep and that this effect depends on COPD severity.

Methods

We performed full polysomnography in COPD patients (n=17; FEV₁, 1.6±0.6 L) and in matched controls (n=8). Participants received room air (RA) at baseline and single night treatment with O₂ (2 L/min) and NHF (20 L/min) in a random order. Finger pulse wave amplitude (PWA), a measure of vascular sympathetic tone, was assessed by photoplethysmography. Autonomic activation (AA) events were defined as PWA attenuation ≥30% and indexed per hour for sleep stages (AA index [AAI]) at RA, NHF, and O₂).

Results

In COPD, sleep apnea improved following O₂ (REM-apnea hypopnea index [AHI] with RA, O₂, and NHF: 18.6±20.9, 12.7±18.1, and 14.4±19.8, respectively; P=0.04 for O₂ and P=0.06 for NHF). REM-AAI was reduced only following NHF in COPD patients (AAI-RA, 21.5±18.4 n/h and AAI-NHF, 9.9±6.8 n/h, P=0.02) without changes following O₂ (NHF-O₂ difference, P=0.01). REM-AAI reduction was associated with lung function expressed as FEV₁ and FVC (FEV₁: r=−0.59, P=0.001; FEV₁/FVC: r=−0.52 and P=0.007).

Conclusion

NHF but not elevated oxygenation reduces peripheral vascular sympathetic activity in COPD patients during REM sleep. Sympathetic off-loading by NHF, possibly related to improved breathing mechanics, showed a strong association with COPD severity.

Morning surge in blood pressure and sympathetic activity in Mongolians and Han Chinese: a multimodality investigation of hypertension and dyssomnia

Background

Hypertension and dyssomnia are increasing significantly in Mongolians, and the related factors of ethnic differences in hypertension and dyssomnia between Mongolians and Han Chinese are unclear. This study examined the relationship of morning surge in blood pressure (MBP) with ethnicity, sleep situation, and sympathetic activity throughout the day.

Methods

Of 692 hypertensive patients screened, 202 subjects with dyssomnia were selected. They were then divided into Mongolian (n = 87) and Han (n = 115) groups. The differences in dyssomnia, 24-h blood pressure, and urinary catecholamine were analyzed in all subjects; they were then further divided according to the degree of dyssomnia (low, moderate, and severe) to determine the differences in blood pressure and catecholamine.

Results

Mongolians had a lower history of smoking, daytime dysfunction, nocturnal heart rates, and dopamine levels, but their body mass index, triglyceride, fasting glucose, morning surge in systolic blood pressure (MSBP), nocturnal systolic blood pressure (NSBP), nocturnal diastolic blood pressure, daytime systolic blood pressure, daytime heart rates, and dopamine level (D-DA) were higher than those of Han Chinese. With the aggravation of dyssomnia, MSBP, NSBP, D-NE, daytime epinephrine, and D-DA of Mongolians and Han Chinese increased gradually, but the rate of increase was faster in the latter (p < 0.05). D-DA was entered into the MSBP regression model of Mongolians (intercept, 157 mmHg), whereas D-DA and D-NE were entered into the MSBP regression model of Han Chinese (intercept, 142 mmHg).

Conclusion

Worsened dyssomnia induces higher MSBP and augments sympathetic excitability in Mongolians and Han Chinese. Mongolians with hypertension and dyssomnia had higher MSBP baseline and D-DA but lower N-DA. With an increase in D-DA, MSBP in Han and Mongolian patients increased gradually.

Scoring criteria for portable monitor recordings: a comparison of four hypopnoea definitions in a population-based cohort

RATIONALE

Limited-channel portable monitors (PMs) are increasingly used as an alternative to polysomnography (PSG) for the diagnosis of obstructive sleep apnoea (OSA). However, recommendations for the scoring of PM recordings are still lacking. Pulse-wave amplitude (PWA) drops, considered as surrogates for EEG arousals, may increase the detection sensitivity for respiratory events in PM recordings.

OBJECTIVES

To investigate the performance of four different hypopnoea scoring criteria, using 3% or 4% oxygen desaturation levels, including or not PWA drops as surrogates for EEG arousals, and to determine the impact of measured versus reported sleep time on OSA diagnosis.

METHODS

Subjects drawn from a population-based cohort underwent a complete home PSG. The PSG recordings were scored using the 2012 American Academy of Sleep Medicine criteria to determine the apnoea-hypopnoea index (AHI). Recordings were then rescored using only parameters available on type 3 PM devices according to different hypopnoea criteria and patients-reported sleep duration to determine the 'portable monitor AHIs' (PM-AHIs).

MAIN RESULTS

312 subjects were included. Overall, PM-AHIs showed a good concordance with the PSG-based AHI although it tended to slightly underestimate it. The PM-AHI using 3% desaturation without PWA drops showed the best diagnostic accuracy for AHI thresholds of ≥ 5/h and ≥ 15/h (correctly classifying 94.55% and 93.27% of subjects, respectively, vs 80.13% and 87.50% with PWA drops). There was a significant but modest correlation between PWA drops and EEG arousals (r=0.20, p=0.0004).

CONCLUSION

Interpretation of PM recordings using hypopnoea criteria which include 3% desaturation without PWA drops as EEG arousal surrogate showed the best diagnosis accuracy compared with full PSG.

A critical review of peripheral arterial tone and pulse transit time as indirect diagnostic methods for detecting sleep disordered breathing and characterizing sleep structure

PURPOSE OF REVIEW

Sympathetic activity varies continuously across sleep stages. During rapid eye movement sleep, sympathetic tone increases substantially but is highly variable. Microarousals are associated with momentary bursts of sympathetic activity. Abnormal respiratory events progressively elevate sympathetic activity in proportion to the severity of oxyhemoglobin desaturation. These phenomena imply that cardiovascular markers of sympathetic activity such as peripheral arterial tone (PAT) and pulse transit time could be indirect tools for diagnosing sleep disordered breathing and characterizing sleep structure and fragmentation.

RECENT FINDINGS

Measurement of variations in PAT coupled with pulse rate accelerations and desaturations in oximetry can be used to diagnose sleep apnea. Good agreement between both manually and automatically analyzed PAT recordings and polysomnography has been demonstrated during in-laboratory or at-home studies. Numerous validation studies against esophageal pressure have demonstrated that pulse transit time is the best noninvasive method for measurement of respiratory effort. Pulse transit time and PAT are sensitive techniques for arousal recognition, particularly in children and infants. There are specific sleep stage-dependent PAT patterns that allow for the recognition of rapid eye movement sleep and, in the case of nonrapid eye movement sleep, the separation of lighter stages from deeper, slow wave sleep. Elevated nocturnal sympathetic activity as documented by PAT attenuations is linked with chronically elevated blood pressure in humans.

SUMMARY

Cardiovascular markers of autonomic control during sleep permit not only the diagnosis of obstructive sleep apnea and estimation of sleep structure but are also linked with the prevalence of daytime hypertension.

Sleep staging based on autonomic signals: a multi-center validation study

STUDY OBJECTIVES

One of the most important caveats of ambulatory devices is the inability to record and stage sleep. We assessed an algorithm determining 4 different stages: wake, light sleep, deep sleep, and REM sleep using signals derived from the portable monitor Watch-PAT100 (PAT recorder).

METHODS

Participants (38 normal subjects and 189 patients with obstructive sleep apnea [OSA]) underwent simultaneous overnight recordings with polysomnography (PSG) and the PAT recorder in a study originally designed to assess the accuracy of the PAT recorder in diagnosing OSA. Light/deep sleep and REM sleep from the PAT recorder recording were automatically scored based on features extracted from time series of peripheral arterial tone amplitudes and inter pulse periods. The PSG scored sleep stages 1 and 2 were classified as light sleep for epoch-by-epoch comparisons.

RESULTS

The overall agreement in detecting light/deep and REM sleep were 88.6% ± 5.9% and 88.7% ± 5.5%, respectively. There was a good agreement between PSG and the PAT recorder in quantifying sleep efficiency (78.4% ± 9.9% vs. 78.8% ± 13.4%), REM latency (237 ± 148 vs. 225 ± 159 epochs), and REM percentage (14.4% ± 6.5% vs. 19.3% ± 8.7%). OSA severity did not affect the sensitivity and specificity of the algorithm. The Cohen κ coefficient for detecting all sleep stages: sleep from wake, REM from NREM sleep, and deep from light sleep were 0.48, 0.55, 0.59, and 0.46, respectively.

CONCLUSIONS

Analysis of autonomic signals from the PAT recorder can detect sleep stages with moderate agreement to more standard techniques in normal subjects and OSA patients. This novel algorithm may provide insights on sleep and sleep architecture when applying the PAT recorder for OSA diagnosis.

Pulse wave amplitude drops during sleep are reliable surrogate markers of changes in cortical activity

BACKGROUND

During sleep, sudden drops in pulse wave amplitude (PWA) measured by pulse oximetry are commonly associated with simultaneous arousals and are thought to result from autonomic vasoconstriction. In the present study, we determine whether PWA drops were associated with changes in cortical activity as determined by EEG spectral analysis.

METHODS

A 20% decrease in PWA was chosen as a minimum for a drop. A total of 1085 PWA drops from 10 consecutive sleep recordings were analyzed. EEG spectral analysis was performed over 5 consecutive epochs of 5 seconds: 2 before, 1 during, and 2 after the PWA drop. EEG spectral analysis was performed over delta, theta, alpha, sigma, and beta frequency bands. Within each frequency band, power density was compared across the five 5-sec epochs. Presence or absence of visually scored EEG arousals were adjudicated by an investigator blinded to the PWA signal and considered associated with PWA drop if concomitant.

RESULTS

A significant increase in EEG power density in all EEG frequency bands was found during PWA drops (P<0.001) compared to before and after drop. Even in the absence of visually scored arousals, PWA drops were associated with a significant increase in EEG power density (P<0.001) in most frequency bands.

CONCLUSIONS

Drops in PWA are associated with a significant increase in EEG power density, suggesting that these events can be used as a surrogate for changes in cortical activity during sleep. This approach may prove of value in scoring respiratory events on limited-channel (type III) portable monitors.