Baroreflex function and postprandial hypotension in older adults

Correlation between postprandial hypotension and post-induction hypotension in the elderly: a protocol for a prospective cohort study

INTRODUCTION

Post-induction hypotension (PIH) is particularly common in elderly patients undergoing general anaesthesia and is associated with severe postoperative complications. Autonomic nervous system (ANS) dysfunction is a potential risk factor for significant haemodynamic fluctuations during general anaesthesia in elderly patients. Tools to identify ANS are currently lacking in perioperative clinical practice. Postprandial hypotension (PPH) is closely linked to ANS dysfunction and is also common among elderly individuals. Therefore, this study aims to explore the relationship between PPH and PIH in elderly patients undergoing non-cardiac surgery. By examining this correlation, we hope to better understand the factors contributing to PIH and explore the potential role of PPH in predicting PIH.

METHODS AND ANALYSIS

This is a prospective observational cohort study. 120 elderly Chinese patients aged ≥65 years and scheduled to undergo non-cardiac surgery under general anaesthesia at Peking Union Medical College Hospital (PUMCH) will be included. PPH assessments will include baseline pre-prandial records and blood pressure measurements immediately after meal completion, followed by every 5 min for 120 min. To evaluate PIH, blood pressure will be monitored from the patients' entry into the operating room until 20 min after anaesthesia induction or the initiation of surgery. PIH is defined as systolic blood pressure of <90 mmHg or main arterial pressure <65 mmHg or a decrease of more than 30% from baseline within 20 min after general anaesthesia induction or before surgical incision. Baseline assessment will include regular preoperative assessment, symptoms and medical history related to baroreflex dysfunction, and preoperative volume status will be assessed by passive leg raising test. Follow-up will be conducted at 1, 3, 7 and 30 days and 6 months postoperatively. The primary outcome is PIH. Secondary outcomes include early intraoperative hypotension, postoperative complications graded by Clavien-Dindo classification, 30-day postoperative mortality and 12-item WHO Disability Assessment Schedule 2.0 (12-item WHODAS 2.0) score 6 months postoperatively.

ETHICS AND DISSEMINATION

This study has been registered in the ClinicalTrials.gov system of the National Institutes of Health (registration number NCT05575661). The Ethics Committee of PUMCH has also granted ethical approval (approval number I-22PJ008). The study results will be disseminated through publication in peer-reviewed journals focused on anaesthesiology and geriatric medicine, as well as presentations at relevant scientific conferences.

TRIAL REGISTRATION NUMBER

NCT05575661.

Acustimulation combined with pharmacological prophylaxis versus pharmacological prophylaxis alone in postoperative nausea and vomiting (PONV) prophylaxis among patients undergoing laparoscopy abdominal surgery: a research protocol for a randomised controlled trial

INTRODUCTION

This study evaluates the efficacy of integrating percutaneous electrical nerve stimulation at the pericardium 6 (PC6) acupuncture point through a wearable acustimulation device with standard pharmacological prophylaxis to prevent postoperative nausea and vomiting (PONV) compared with pharmacological prophylaxis alone in patients undergoing laparoscopic abdominal surgery.

METHOD AND ANALYSIS

This prospective study will enrol 302 patients scheduled for elective laparoscopic surgery. Participants will be randomly allocated to one of two groups: acustimulation combined with pharmacological prophylaxis or sham stimulation combined with pharmacological prophylaxis. Randomisation will involve a computer-generated sequence, with allocation concealment implemented through sealed envelopes. The acustimulation group will receive electrical stimulation at the PC6 point starting 30 min before surgery and continuing until discharge from the postanaesthesia care unit. Sham group will wear a wristband that does not provide stimulation. The primary outcome is the incidence of PONV. Secondary outcomes include the severity of PONV, incidence rates of nausea and vomiting at different postoperative intervals and indices of gastrointestinal functional recovery. Exploratory outcomes will assess haemodynamic parameters, baroreflex sensitivity, hospital stay duration, costs and both short-term and long-term postoperative recovery.

ETHICS AND DISSEMINATION

All participants will provide written informed consent. The study has been approved by the Ethics Committee of Peking Union Medical Hospital (approval number: I-23PJ1712). Results will be published open access.

TRIAL REGISTRATION NUMBER

NCT06241547.

Prevalence of postprandial hypotension in older adults: a systematic review and meta-analysis

BACKGROUND

Older adults with postprandial hypotension (PPH) increase susceptibility to falls, syncope, stroke, acute cardiovascular diseases and even death. However, the prevalence of this condition varies significantly across studies. We aimed to determine the prevalence of PPH in older adults.

METHODS

Web of Science, PubMed, Cochrane Library, Embase and CINAHL were searched from their inception until February 2023. Search terms included 'postprandial period', 'hypotension' and 'postprandial hypotension'. Eligible studies were assessed using the Joanna Briggs Institute tool. Meta-analyses were performed among similar selected studies.

RESULTS

Thirteen eligible studies were included, and data from 3,021 participants were pooled. The meta-analysis revealed a PPH prevalence of 40.5% [95% confidence interval (CI): 0.290-0.519] in older adults, and this was prevalent in the community (32.8%, 95% CI: 0.078-0.647, n = 1,594), long-term healthcare facility (39.4%, 95% CI: 0.254-0.610, n = 1,062) and geriatrics department of hospitals (49.3%, 95% CI: 0.357-0.630, n = 365). The pooled results showed significant heterogeneity (I2 > 90%), partially related to the different ages, sex, pre-prandial systolic blood pressure levels of participants, or the different criteria and methodology used to diagnose PPH.

CONCLUSIONS

PPH is a prevalent condition in older adults. Further research is needed to confirm this result, and priority should be given to establishing international consensus on PPH diagnostic criteria and designing its diagnostic procedure.

Association between preoperative autonomic nervous system function and post-induction hypotension in elderly patients: a protocol for a cohort study

INTRODUCTION

Post-induction hypotension (PIH), which is prevalent among elderly patients, is associated with adverse perioperative outcomes. As a critical part of blood pressure regulation, baroreflex control is believed to be closely related to intraoperative blood pressure fluctuations. Spontaneous baroreflex sensitivity and heart rate variability measurement can aid evaluation of patients' autonomic function. This study aims to determine the association between preoperative decreased baroreflex function and PIH in elderly patients.

METHODS AND ANALYSIS

This prospective cohort study will enrol patients who are 65 years old and above, scheduled for elective non-cardiac surgery under general anaesthesia, and American Society of Anesthesiologists physical status I-III (n=180). Baseline assessment will include routine preoperative evaluations as well as symptoms and anamneses associated with baroreflex failure. Preoperative autonomic function monitoring will be performed through 20 min of continuous beat-to-beat heart rate and blood pressure monitoring using LiDCO rapid (Masimo Corporation, USA). The primary outcome will be PIH. Detailed use of anaesthetic agents during induction and maintenance will be documented for adjustment in multivariable analyses.

ETHICS AND DISSEMINATION

The Research Ethics Committee of Peking Union Medical College Hospital approved the study protocol (I-22PJ008). We aim to publish and disseminate our findings in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05425147.

Pure Autonomic Failure-A Localized Alpha Synucleinopathy with a Potential for Conversion to More Extensive Alpha Synucleinopathies

Pure autonomic failure (PAF) is an alpha synucleinopathy with predominant involvement of the autonomic ganglia and peripheral nerves. The hallmark clinical feature is orthostatic hypotension. However, genitourinary, sudomotor, and cardiac involvement is also common. Many patients also develop supine hypertension. Almost a quarter of patients can phenoconvert or evolve into Parkinson's disease, multiple system atrophy, and Lewy body dementia in the future. Early severe bladder involvement, higher supine noradrenaline level, early motor involvement, and dream enactment behavior increase the risk of phenoconversion. The diagnosis is confirmed via autonomic function testing and serum noradrenaline measurement. The treatment is mainly supportive. The non-pharmacological treatment includes adequate fluid, dietary salt, compression stockings, and abdominal binders. The drug therapies to improve blood pressure include midodrine, fludrocortisone, pyridostigmine, and droxidopa. The diagnostic criteria need to be updated to incorporate the recent understandings. The treatment of orthostatic hypotension and supine hypertension is mainly based on case series and anecdotal reports. Randomized control trials are needed to ascertain the best treatment strategies for PAF.

Cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension at rest and during orthostatic stress: role of the peripheral chemoreflex

The baroreflex integrity in early-stage pulmonary arterial hypertension (PAH) remains uninvestigated. A potential baroreflex impairment could be functionally relevant and possibly mediated by enhanced peripheral chemoreflex activity. Thus, we investigated 1) the cardiac baroreflex in nonhypoxemic PAH; 2) the association between baroreflex indexes and peak aerobic capacity [i.e., peak oxygen consumption (V̇o_2peak)]; and 3) the peripheral chemoreflex contribution to the cardiac baroreflex. Nineteen patients and 13 age- and sex-matched healthy adults (HA) randomly inhaled either 100% O₂ (peripheral chemoreceptor inhibition) or 21% O₂ (control session) while at rest and during a repeated sit-to-stand maneuver. Beat-by-beat analysis of R-R intervals and systolic blood pressure provided indexes of cardiac baroreflex sensitivity (cBRS) and effectiveness (cBEI). The PAH group had lower cBEI for all sequences (cBEI_ALL) at rest [means ± SD: PAH = 0.5 ± 0.2 vs. HA = 0.7 ± 0.1 arbitrary units (a.u.), P = 0.02] and lower cBRS_ALL (PAH = 6.8 ± 7.0 vs. HA = 9.7 ± 5.0 ms·mmHg^-1, P < 0.01) and cBEI_ALL (PAH = 0.4 ± 0.2 vs. HA= 0.6 ± 0.1 a.u., P < 0.01) during the sit-to-stand maneuver versus the HA group. The cBEI during the sit-to-stand maneuver was independently correlated to V̇o_2peak (partial r = 0.45, P < 0.01). Hyperoxia increased cBRS and cBEI similarly in both groups at rest and during the sit-to-stand maneuver. Therefore, cardiac baroreflex dysfunction was observed under spontaneous and, most notably, provoked blood pressure fluctuations in nonhypoxemic PAH, was not influenced by the peripheral chemoreflex, and was associated with lower V̇o_2peak, suggesting that it could be functionally relevant.NEW & NOTEWORTHY Does the peripheral chemoreflex play a role in cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension (PAH)? Here we provide new evidence of cardiac baroreflex dysfunction under spontaneous and, most notably, provoked blood pressure fluctuations in patients with nonhypoxemic PAH. Importantly, impaired cardiac baroreflex effectiveness during provoked blood pressure fluctuations was independently associated with poorer functional capacity. Finally, our results indicated that the peripheral chemoreflex did not mediate cardiac baroreflex dysfunction among those patients.