Pathophysiology of syncope: current concepts and their development.

Syncope is a symptom in which transient loss of consciousness occurs as a consequence of a self-limited, spontaneously terminating period of cerebral hypoperfusion. Many circulatory disturbances (e.g. brady- or tachyarrhythmias, reflex cardioinhibition-vasodepression-hypotension) may trigger a syncope or near-syncope episode, and identifying the cause(s) is often challenging. Some syncope may involve multiple etiologies operating in concert, whereas in other cases multiple syncope events may be due to various differing causes at different times. In this communication, we address the current understanding of the principal contributors to syncope pathophysiology including examination of the manner in which concepts evolved, an overview of factors that constitute consciousness and loss of consciousness, and aspects of neurovascular control and communication that are impacted by cerebral hypoperfusion leading to syncope. Emphasis focuses on 1) current understanding of the way transient systemic hypotension impacts brain blood flow and brain function; 2) the complexity and temporal sequence of vascular, humoral, and cardiac factors that may accompany the most common causes of syncope; 3) the range of circumstances and disease states that may lead to syncope; and 4) clinical features associated with syncope and in particular the reflex syncope syndromes.

Clinical Outcomes of Patients Experiencing Transient Loss of Pulse Pressure During High-Risk PCI with Impella.

BACKGROUND: Patients experiencing loss of pulse pressure (LOPP) during high-risk percutaneous coronary intervention (HR-PCI) are transiently dependent on mechanical circulatory support devices. We sought to define the frequency and clinic outcomes of patients who experience LOPP during HR-PCI. METHODS AND RESULTS: Patients enrolled in the PROTECT III study and had automated Impella controller logs capturing real-time hemodynamics were included in this analysis. A LOPP event was defined as a mean pulse pressure on Impella of <20 mm Hg for ≥5 seconds during PCI. Clinical characteristics and outcomes were then compared between those with and without LOPP. Logistic regression identified clinical and hemodynamic predictors of LOPP. We included 302 patients, of whom 148 patients (49%) experienced LOPP. Age, sex, and comorbidities were similar in patients with and without LOPP. Mean baseline systolic blood pressure (118.6 mm Hg vs 129.8 mm Hg; P < .001) and mean arterial pressure (86.9 mm Hg vs 91.6 mm Hg; P = .011) were lower in patients with LOPP, whereas heart rate (78 bpm vs 73 bpm; P = .012) was higher. Anatomical complexity was similar between groups. Patients with LOPP were more likely to experience major adverse cardiac and cerebrovascular events (23.5% vs 8.8%; P = .002), acute kidney injury (10.1% vs 2.6%; P = .030), and death (20.2% vs 7.9%; P = .008) within 90 days. A low baseline systolic blood pressure and cardiomyopathy were the strongest predictors of LOPP (P = .003 and P = .001, respectively). CONCLUSIONS: LOPP on Impella during HR-PCI was common and occurred more frequently in patients with cardiomyopathy and a low systolic blood pressure. LOPP was strongly associated with higher 90-day major adverse cardiac and cerebrovascular events, acute kidney injury, and mortality. Condensed Abstract We sought to define the frequency and clinic outcomes of patients who experience LOPP during high-risk percutaneous coronary intervention (HR-PCI). We included 302 patients, of whom 148 (49%) experienced LOPP. Patients with LOPP were more likely to experience major adverse cardiac and cerebrovascular events (23.5% vs 8.8%; P = .002), acute kidney injury (10.1% vs 2.6%; P = .030), and death (20.2% vs 7.9%; P = .008) within 90 days. A low baseline systolic blood pressure and cardiomyopathy were the strongest predictors of LOPP (P = .003 and P = .001, respectively).

Fructose-1,6-bisphosphate reverses hypotensive effect caused by L-kynurenine in Wistar male rats.

Hypotension is one of the main characteristics of the systemic inflammation, basically caused by endothelial dysfunction. Studies have shown that the amino acid L-kynurenine (KYN) causes vasodilation in mammals, leading to hypotensive shock. In hypotensive shock, when activated by the KYN, the voltage-gated potassium channel encoded by the family KCNQ (Kv7) gene can cause vasodilation. Fructose-1,6-bisphosphate (FBP) it is being considered in studies an anti-inflammatory, antioxidant, immunomodulator, and a modulator of some ion channels (Ca2+, Na+, and K+). We analyzed the effects of KYN and FBP on mean blood pressure (MBP), systolic and diastolic (DBP) blood pressure, and heart rate variability (HRV) in Wistar rats. Results demonstrated that the administration of KYN significant decreased MBP, DBP, and increased HRV. Importantly, the FBP treatment reversed the KYN effects on MBP, DBP, and HRV. Molecular Docking Simulations suggested that KYN and FBP present a very close estimated free energy of binding and the same position into structure of KCNQ4. Our results did demonstrate that FBP blunted the decrease in BP, provoked by KYN. Results raise new hypotheses for future and studies in the treatment of hypotension resulting from inflammation.

Risk stratification by renal function and NYHA class in patients with hypotension initiated on sacubitril/valsartan: a retrospective cohort study from 17 centres in Japan.

BACKGROUND: Patients with heart failure exhibiting low systolic blood pressure (SBP) have a poor prognosis. Sacubitril/valsartan reduces cardiovascular events; however, its use in patients with low SBP has not been fully examined. Therefore, in this study, we aimed to investigate the association between baseline SBP and adverse events (AEs) in patients starting sacubitril/valsartan therapy using data from a real-world registry in Japan. METHODS: We analysed data from a multicentre retrospective study, including patients who initiated sacubitril/valsartan between August 2020 and August 2021. The patients were categorised into five groups based on their baseline SBP (<100, 100-109, 110-119, 120-129 and ≥130 mm Hg). The composite of AEs occurring within 3 months according to baseline SBP and the patient characteristics associated with AEs in a baseline SBP <110 mm Hg were analysed. RESULTS: Among the 964 patients newly prescribed sacubitril/valsartan, the median (IQR) age was 73 (61-80) years, and 388 (40.2%) patients had a baseline SBP <110 mm Hg. AEs occurred in 24% (n=232) of patients. The adjusted ORs for all AEs were 1.91 (95% CI (CI) 1.13-3.23; p=0.02) for the SBP <100 mm Hg group and 3.33 (95% CI 1.98 to 5.59; p<0.001) for the SBP 100-109 mm Hg group, compared with the SBP 110-119 mm Hg group. In patients with a baseline SBP <110 mm Hg, factors associated with an increased risk of AEs included a higher New York Heart Association class (II, III or IV) and a lower estimated glomerular filtration rate <30 mL/min/1.73 m2. CONCLUSIONS: Caution is needed when initiating sacubitril/valsartan in patients with lower baseline SBP. The severity of heart failure and kidney function may be useful for risk stratification in these high-risk patients.

ALM Resuscitation With Brain and Multiorgan Protection for Far-Forward Operations: Survival at Hypotensive Pressures.

INTRODUCTION: Non-compressible torso hemorrhagic (NCTH) shock is the leading cause of potentially survivable trauma on the battlefield. New hypotensive drug therapies are urgently required to resuscitate and protect the heart and brain following NCTH. Our aim was to examine the strengths and limitations of permissive hypotension and discuss the development of small-volume adenosine, lidocaine, and Mg2+ (ALM) fluid resuscitation in rats and pigs. MATERIALS AND METHODS: For review of permissive hypotension, a literature search was performed from inception up to November 2023 using PubMed, Cochrane, and Embase databases, with inclusion of animal studies, clinical trials and reviews with military and clinical relevance. For the preclinical study, adult female pigs underwent laparoscopic liver resection. After 30 minutes of bleeding, animals were resuscitated with 4 mL/kg 3% NaCl ± ALM bolus followed 60 minutes later with 4 h 3 mL/kg/h 0.9% NaCl ± ALM drip (n = 10 per group), then blood transfusion. Mean arterial pressure (MAP) and cardiac output (CO) were continuously measured via a left ventricular pressure catheter and pulmonary artery catheter, respectively. Systemic vascular resistance (SVR) was calculated using the formula: 80 × (MAP - CVP)/CI. Oxygen delivery was calculated as the product of CO and arterial oxygen content. RESULTS: Targeting a MAP of ∼50 mmHg can be harmful or beneficial, depending on how CO and SVR are regulated. A theoretical example shows that for the same MAP of 50 mmHg, a higher CO and lower SVR can lead to a nearly 2-fold increase in O2 supply. We further show that in animal models of NCTH, 3% NaCl ALM bolus and 0.9% NaCl ALM drip induce a hypotensive, high flow, vasodilatory state with maintained tissue O2 supply and neuroprotection. ALM therapy increases survival by resuscitating the heart, reducing internal bleeding by correcting coagulopathy, and decreasing secondary injury. CONCLUSIONS: In rat and pig models of NCTH, small-volume ALM therapy resuscitates at hypotensive pressures by increasing CO and reducing SVR. This strategy is associated with heart and brain protection and maintained tissue O2 delivery. Translational studies are required to determine reproducibility and optimal component dosing. ALM therapy may find wide utility in prehospital and far-forward military environments.

Postprandial hypotension is more common than orthostatic hypotension in older adults with dementia with lewy bodies: a cross-sectional study.

Cardiovascular autonomic dysfunction is one of the supportive clinical features in dementia with Lewy bodies (DLB). This study aimed to investigate the frequency of postural and postprandial hypotension in people with DLB. The study group comprised 125 patients with DLB (76 females; mean age 78.4 ± 7.1 years) and 122 controls (88 females; mean age 74.4 ± 6.9 years). Postprandial blood pressure changes were assessed by ambulatory 24-hour blood pressure monitorization. Postural blood pressure changes were assessed via the head-up tilt table test. The frequency of postprandial hypotension (PPH) and orthostatic hypotension (OH) was higher in patients with DLB compared to controls (89.4% vs 51.7%; p < 0.001, and 45.5% vs 27.9%; p = 0.004, respectively) whereas the frequency of supine hypertension (SH), and orthostatic hypertension (OHT) was similar. However, SH in non-hypertensive participants was higher in DLB patients than in controls (48.9%, 25.7%; p = 0.035). PPH and OH were independently associated with a diagnosis of DLB (odds ratio [OR]:10.26 confidence interval [CI]%95 3.02-34.82; p < 0.001, and OR:2.22 CI%95 1.2-4.12; p = 0.012, respectively) after adjustment for age, number of medications, use of anti-psychotics drugs, angiotensin receptor blockers, and beta blockers. In conclusion, the study demonstrated that PPH was the most common finding of cardiovascular autonomic dysfunction, followed by OH and SH in older patients with DLB. Given the potential complications of postural blood pressure changes and PPH in such patients, cardiovascular autonomic dysfunction should be evaluated in patients with DLB.

Ingesting carbonated water post-exercise in the heat transiently ameliorates hypotension and enhances mood state.

The objective was to assess if post-exercise ingestion of carbonated water in a hot environment ameliorates hypotension, enhances cerebral blood flow and heat loss responses, and positively modulates perceptions and mood states. Twelve healthy, habitually active young adults (five women) performed 60 min of cycling at 45% peak oxygen uptake in a hot climate (35°C). Subsequently, participants consumed 4°C carbonated or non-carbonated (control) water (150 and 100 mL for males and females regardless of drink type) at 20 and 40 min into post-exercise periods. Mean arterial pressure decreased post-exercise at 20 min only (P = 0.032) compared to the pre-exercise baseline. Both beverages transiently (∼1 min) increased mean arterial pressure and middle cerebral artery mean blood velocity (cerebral blood flow index) regardless of post-exercise periods (all P ≤ 0.015). Notably, carbonated water ingestion led to greater increases in mean arterial pressure (2.3 ± 2.8 mmHg vs. 6.6 ± 4.4 mmHg, P < 0.001) and middle cerebral artery mean blood velocity (1.6 ± 2.5 cm/s vs. 3.8 ± 4.1 cm/s, P = 0.046) at 20 min post-exercise period compared to non-carbonated water ingestion. Both beverages increased mouth exhilaration and reduced sleepiness regardless of post-exercise periods, but these responses were more pronounced with carbonated water ingestion at 40 min post-exercise (mouth exhilaration: 3.1 ± 1.4 vs. 4.7 ± 1.7, P = 0.001; sleepiness: -0.7 ± 0.91 vs. -1.9 ± 1.6, P = 0.014). Heat loss responses and other perceptions were similar between the two conditions throughout (all P ≥ 0.054). We show that carbonated water ingestion temporarily ameliorates hypotension and increases the cerebral blood flow index during the early post-exercise phase in a hot environment, whereas it enhances mouth exhilaration and reduces sleepiness during the late post-exercise phase.

Predictive ability of hypotension prediction index and machine learning methods in intraoperative hypotension: a systematic review and meta-analysis.

INTRODUCTION: Intraoperative Hypotension (IOH) poses a substantial risk during surgical procedures. The integration of Artificial Intelligence (AI) in predicting IOH holds promise for enhancing detection capabilities, providing an opportunity to improve patient outcomes. This systematic review and meta analysis explores the intersection of AI and IOH prediction, addressing the crucial need for effective monitoring in surgical settings. METHOD: A search of Pubmed, Scopus, Web of Science, and Embase was conducted. Screening involved two-phase assessments by independent reviewers, ensuring adherence to predefined PICOS criteria. Included studies focused on AI models predicting IOH in any type of surgery. Due to the high number of studies evaluating the hypotension prediction index (HPI), we conducted two sets of meta-analyses: one involving the HPI studies and one including non-HPI studies. In the HPI studies the following outcomes were analyzed: cumulative duration of IOH per patient, time weighted average of mean arterial pressure < 65 (TWA-MAP < 65), area under the threshold of mean arterial pressure (AUT-MAP), and area under the receiver operating characteristics curve (AUROC). In the non-HPI studies, we examined the pooled AUROC of all AI models other than HPI. RESULTS: 43 studies were included in this review. Studies showed significant reduction in IOH duration, TWA-MAP < 65 mmHg, and AUT-MAP < 65 mmHg in groups where HPI was used. AUROC for HPI algorithms demonstrated strong predictive performance (AUROC = 0.89, 95CI). Non-HPI models had a pooled AUROC of 0.79 (95CI: 0.74, 0.83). CONCLUSION: HPI demonstrated excellent ability to predict hypotensive episodes and hence reduce the duration of hypotension. Other AI models, particularly those based on deep learning methods, also indicated a great ability to predict IOH, while their capacity to reduce IOH-related indices such as duration remains unclear.

Effect of low blood pressure on prognosis of acute heart failure.

Low blood pressure (BP) is associated with poor outcomes in patients with heart failure (HF). We investigated the influence of initial BP on the prognosis of HF patients at admission, and prescribing patterns of HF medications, such as angiotensin-converting enzyme inhibitors (ACEi), angiotensin receptor blockers (ARB), and beta-blockers (BB). Data were sourced from a multicentre cohort of patients admitted for acute HF. Patients were grouped into heart failure reduced ejection fraction (HFrEF) and HF mildly reduced/preserved ejection fraction (HFmrEF/HFpEF) groups. Initial systolic and diastolic BPs were categorized into specific ranges. Among 2778 patients, those with HFrEF were prescribed ACEi, ARB, or BB at discharge, regardless of their initial BP. However, medication use in HFmrEF/HFpEF patients tended to decrease as BP decreased. Lower initial BP in HFrEF patients correlated with an increased incidence of all-cause death and composite clinical events, including HF readmission or all-cause death. However, no significant differences in clinical outcomes were observed in HFmrEF/HFpEF patients according to BP. Initial systolic (< 120 mmHg) and diastolic (< 80 mmHg) BPs were independently associated with a 1.81-fold (odds ratio [OR] 1.81, 95% confidence interval [CI] 1.349-2.417, p < 0.001) and 2.24-fold (OR 2.24, 95% CI 1.645-3.053, p < 0.001) increased risk of long-term mortality in HFrEF patients, respectively. In conclusion, low initial BP in HFrEF patients correlated with adverse clinical outcomes, and BP < 120/80 mmHg independently increased mortality. However, this relationship was not observed in HFmrEF/HFpEF patients.

Ion Channels Remodeling in the Regulation of Vascular Hyporesponsiveness During Shock.

Shock is characterized with vascular hyporesponsiveness to vasoconstrictors, thereby to cause refractory hypotension, insufficient tissue perfusion, and multiple organ dysfunction. The vascular hyporeactivity persisted even though norepinephrine and fluid resuscitation were administrated, it is of critical importance to find new potential target. Ion channels are crucial in the regulation of cell membrane potential and affect vasoconstriction and vasodilation. It has been demonstrated that many types of ion channels including K+ channels, Ca2+ permeable channels, and Na+ channels exist in vascular smooth muscle cells and endothelial cells, contributing to the regulation of vascular homeostasis and vasomotor function. An increasing number of studies suggested that the structural and functional alterations of ion channels located in arteries contribute to vascular hyporesponsiveness during shock, but the underlying mechanisms remained to be fully clarified. Therefore, the expression and functional changes in ion channels in arteries associated with shock are reviewed, to pave the way for further exploring the potential of ion channel-targeted compounds in treating refractory hypotension in shock.

Accuracy of oscillometric noninvasive blood pressure at the ankle in the lateral position during general anesthesia.

BACKGROUND: This study aimed to evaluate the accuracy of ankle blood pressure measurements in relation to invasive blood pressure in the lateral position. METHODS: This prospective observational study included adult patients scheduled for elective non-cardiac surgery under general anesthesia in the lateral position. Paired radial artery invasive and ankle noninvasive blood pressure readings were recorded in the lateral position using GE Carescape B650 monitor. The primary outcome was the ability of ankle mean arterial pressure (MAP) to detect hypotension (MAP < 70 mmHg) using area under the receiver operating characteristic curve (AUC) analysis. The secondary outcomes were the ability of ankle systolic blood pressure (SBP) to detect hypertension (SBP > 140 mmHg) as well as bias (invasive measurement - noninvasive measurement), and agreement between the two methods using the Bland-Altman analysis. RESULTS: We analyzed 415 paired readings from 30 patients. The AUC (95% confidence interval [CI]) of ankle MAP for detecting hypotension was 0.88 (0.83-0.93). An ankle MAP of ≤ 86 mmHg had negative and positive predictive values (95% CI) of 99 (97-100)% and 21 (15-29)%, respectively, for detecting hypotension. The AUC (95% CI) of ankle SBP to detect hypertension was 0.83 (0.79-0.86) with negative and positive predictive values (95% CI) of 95 (92-97)% and 36 (26-46)%, respectively, at a cutoff value of > 144 mmHg. The mean bias between the two methods was - 12 ± 17, 3 ± 12, and - 1 ± 11 mmHg for the SBP, diastolic blood pressure, and MAP, respectively. CONCLUSION: In patients under general anesthesia in the lateral position, ankle blood pressure measurements are not interchangeable with the corresponding invasive measurements. However, an ankle MAP > 86 mmHg can exclude hypotension with 99% accuracy, and an ankle SBP < 144 mmHg can exclude hypertension with 95% accuracy.

Periprocedural acute haemodynamic decompensation during substrate-based ablation of scar-related ventricular tachycardia: a rare and unpredictable event.

AIMS: Patients with structural heart disease (SHD) undergoing catheter ablation (CA) for ventricular tachycardia (VT) are at considerable risk of periprocedural complications, including acute haemodynamic decompensation (AHD). The PAINESD score was proposed to predict the risk of AHD. The goal of this study was to validate the PAINESD score using the retrospective analysis of data from a large-volume heart centre. METHODS AND RESULTS: Patients who had their first radiofrequency CA for SHD-related VT between August 2006 and December 2020 were included in the study. Procedures were mainly performed under conscious sedation. Substrate mapping/ablation was performed primarily during spontaneous rhythm or right ventricular pacing. A purposely established institutional registry for complications of invasive procedures was used to collect all periprocedural complications that were subsequently adjudicated using the source medical records. Acute haemodynamic decompensation triggered by CA procedure was defined as intraprocedural or early post-procedural (<12 h) development of acute pulmonary oedema or refractory hypotension requiring urgent intervention. The study cohort consisted of 1124 patients (age, 63 ± 13 years; males, 87%; ischaemic cardiomyopathy, 67%; electrical storm, 25%; New York Heart Association Class, 2.0 ± 1.0; left ventricular ejection fraction, 34 ± 12%; diabetes mellitus, 31%; chronic obstructive pulmonary disease, 12%). Their PAINESD score was 11.4 ± 6.6 (median, 12; interquartile range, 6-17). Acute haemodynamic decompensation complicated the CA procedure in 13/1124 = 1.2% patients and was not predicted by PAINESD score with AHD rates of 0.3, 1.8, and 1.1% in subgroups by previously published PAINESD terciles (<9, 9-14, and >14). However, the PAINESD score strongly predicted mortality during the follow-up. CONCLUSION: Primarily substrate-based CA of SHD-related VT performed under conscious sedation is associated with a substantially lower rate of AHD than previously reported. The PAINESD score did not predict these events. The application of the PAINESD score to the selection of patients for pre-emptive mechanical circulatory support should be reconsidered.

Arterial hypotension "magnitude" and neurological outcome during mechanical thrombectomy under general anesthesia.

INTRODUCTION: Mechanical thrombectomy (MT) is the standard of care for the treatment of acute ischemic stroke (AIS) with large vessel occlusion (LVO), but unfavorable outcomes remain common. Procedural arterial hypotension is associated with poor patient outcome. This study aimed to assess the impact of arterial hypotension "magnitude" (a combination of the depth, defined as the percentage relative to baseline arterial blood pressure, and the duration of hypotensive episodes)" during MT on neurological outcome. METHODS: This is a monocentric retrospective study. Charts were reviewed between January 2018 and June 2021. "Patients were eligible if they were 18 years or older, anterior LVO was diagnosed on cerebral imaging" and MT performed under general anesthesia. Mean arterial pressure (MAP) was recorded every 5 min throughout the procedure, and the arterial hypotension "magnitude" was estimated by the area under the curve (AUC) for different thresholds of MAP drops. MAIN OUTCOME MEASURE: The modified Rankin Scale (mRS) at 90 days. MAIN RESULTS: Among the 117 patients analyzed, 46% had poor neurological outcome. Our study showed correlations between poor outcome and a greater procedural AUC of arterial hypotension for the different thresholds: 5% (k 0.18; 95% CI 0.06-0.30; P = 0.007), 10% (k 0.18; 95% CI 0.05-0.30; P = 0.008), 15% (k 0.18; 95% CI 0.04-0.30; P = 0.011), 20% (k 0.18; 95% CI 0.05-0.30; P = 0.010) and 30% (k 0.19; 95% CI 0.05-0.31; P = 0.010). This association persisted after controlling for age, baseline NIHSS score, and ASPECT score. CONCLUSION: The magnitude of hypotension during MT under general anesthesia for AIS is an independent factor of poor outcome at 90 days. These associations have been observed in patients with mild and severe hypotensive episodes.

Blood Pressure Management for Hypotensive Patients in Intensive Care and Perioperative Cardiovascular Settings.

Blood pressure is a critical physiological parameter, particularly in the context of cardiac intensive care and perioperative settings. As a primary indicator of organ perfusion, the maintenance of adequate blood pressure is imperative for the assurance of sufficient tissue oxygen delivery. Among critically ill and major surgery patients, the continuous monitoring of blood pressure is performed as a standard practice for patients. Nonetheless, uncertainties remain regarding blood pressure goals, and there is no consensus regarding blood pressure targets. This review describes the determinants of blood pressure, examine the influence of blood pressure on organ perfusion, and synthesize the current clinical evidence from various intensive care and perioperative settings to provide a concise guidance for daily clinical practice.

Frequency Domain Deep Learning With Non-Invasive Features for Intraoperative Hypotension Prediction.

BACKGROUND: Intraoperative hypotension can lead to postoperative organ dysfunction. Previous studies primarily used invasive arterial pressure as the key biosignal for the detection of hypotension. However, these studies had limitations in incorporating different biosignal modalities and utilizing the periodic nature of biosignals. To address these limitations, we utilized frequency-domain information, which provides key insights that time-domain analysis cannot provide, as revealed by recent advances in deep learning. With the frequency-domain information, we propose a deep-learning approach that integrates multiple biosignal modalities. METHODS: We used the discrete Fourier transform technique, to extract frequency information from biosignal data, which we then combined with the original time-domain data as input for our deep learning model. To improve the interpretability of our results, we incorporated recent interpretable modules for deep-learning models into our analysis. RESULTS: We constructed 75 994 segments from the data of 3226 patients to predict hypotension during surgery. Our proposed frequency-domain deep-learning model outperformed conventional approaches that rely solely on time-domain information. Notably, our model achieved a greater increase in AUROC performance than the time-domain deep learning models when trained on non-invasive biosignal data only (AUROC 0.898 [95% CI: 0.885-0.91] vs. 0.853 [95% CI: 0.839-0.867]). Further analysis revealed that the 1.5-3.0 Hz frequency band played an important role in predicting hypotension events. CONCLUSION: Utilizing the frequency domain not only demonstrated high performance on invasive data but also showed significant performance improvement when applied to non-invasive data alone. Our proposed framework offers clinicians a novel perspective for predicting intraoperative hypotension.

LDSG-Net: an efficient lightweight convolutional neural network for acute hypotensive episode prediction during ICU hospitalization.

Objective. Acute hypotension episode (AHE) is one of the most critical complications in intensive care unit (ICU). A timely and precise AHE prediction system can provide clinicians with sufficient time to respond with proper therapeutic measures, playing a crucial role in saving patients' lives. Recent studies have focused on utilizing more complex models to improve predictive performance. However, these models are not suitable for clinical application due to limited computing resources for bedside monitors.Approach. To address this challenge, we propose an efficient lightweight dilated shuffle group network. It effectively incorporates shuffling operations into grouped convolutions on the channel and dilated convolutions on the temporal dimension, enhancing global and local feature extraction while reducing computational load.Main results. Our benchmarking experiments on the MIMIC-III and VitalDB datasets, comprising 6036 samples from 1304 patients and 2958 samples from 1047 patients, respectively, demonstrate that our model outperforms other state-of-the-art lightweight CNNs in terms of balancing parameters and computational complexity. Additionally, we discovered that the utilization of multiple physiological signals significantly improves the performance of AHE prediction. External validation on the MIMIC-IV dataset confirmed our findings, with prediction accuracy for AHE 5 min prior reaching 93.04% and 92.04% on the MIMIC-III and VitalDB datasets, respectively, and 89.47% in external verification.Significance. Our study demonstrates the potential of lightweight CNN architectures in clinical applications, providing a promising solution for real-time AHE prediction under resource constraints in ICU settings, thereby marking a significant step forward in improving patient care.

Effects of neuraxial anesthesia in sitting and lateral positions on maternal hemodynamics in cesarean section: A systematic review and meta-analysis.

STUDY OBJECTIVE: During cesarean section, hypotension is a frequent side effect of spinal anesthesia. As a sitting or lateral position is required for spinal anesthesia performance, which of these two positions is more likely to cause intraoperative nausea, vomiting, and hypotension is still unknown. This meta-analysis compared the effects of these two positions on maternal hemodynamics and intraoperative nausea and vomiting. DESIGN: Systematic review and meta-analysis. SETTING: Operating room. PATIENTS: This study included 803 patients from 12 randomized controlled trials (RCTs). INTERVENTIONS: Neuraxial anesthesia in sitting position vs. lateral position. MEASUREMENTS: We chose RCTs comparing the effects of spinal anesthesia in the sitting and lateral positions on maternal hemodynamics by thoroughly searching PubMed, Embase, the Cochrane Library, and the Web of Science for articles published from database inception until October 31, 2022. The Cochrane Handbook was used to assess the methodological quality of each RCT; the results were analyzed using RevMan 5.4 software; and the Egger test was used to assess publication bias. MAIN RESULTS: 12 randomised controlled trials with 803 participants were ultimately included in the final analysis. No significant differences were observed between the two positions in terms of the incidence of hypotension(RR, 0.82; 95% CI, 0.58-1.16; P = 0.26; I2 = 66%), lowest systolic blood pressure(MD, -0.81; 95% CI, -7.38-5.75; P = 0.81; I2 = 86%), the dose of ephedrine(MD, -1.19; 95% CI, -4.91-2.52; P = 0.53; I2 = 83%), and number of parturients requiring ephedrine(RR, 0.97; 95% CI, 0.64-1.46; P = 0.88; I2 = 74%). For the incidence of intraoperative nausea and vomiting, there was no statistical difference between the two positions. CONCLUSION: Parturients undergoing elective cesarean section under spinal anesthesia in the sitting or lateral position experienced similar incidence of hypotension, and there were no significant differences between these two positions in terms of the amount of ephedrine administered or the number of patients needing ephedrine. In both positions, the frequency of nausea and vomiting was comparable. The ideal position for anesthesia can be chosen based on the preferences and individual circumstances of the parturient and anesthesiologist.

Relationship between Tryptase and Hypotension in Anaphylaxis during Anesthesia.

INTRODUCTION: Hypotension is a cardiovascular symptom that appears at the onset of anaphylaxis. It is considered an important factor as it affects the severity of anaphylaxis; however, its details remain to be elucidated. In this study, we investigated the characteristics of hypotension at the onset of anaphylaxis during anesthesia, along with the relationship between hypotension, tryptase and histamine. MATERIALS AND METHODS: The minimum systolic blood pressures of patients diagnosed with anaphylaxis using the clinical diagnostic criteria of the World Allergy Organization guidelines were extracted from electronic anesthesia records. We analyzed changes in tryptase and histamine that were measured after the onset of anaphylaxis. We analyzed the relationship of tryptase and histamine with the minimum systolic blood pressure and the severity of anaphylaxis. RESULTS: Of 55,996 patients, 25 were diagnosed with anaphylaxis during anesthesia (0.045%). Among these patients, the minimum systolic blood pressure was less than 90 mmHg. Furthermore, the minimum systolic blood pressure was inversely correlated with tryptase levels immediately to 1 hour, and 2 to 4 hours after the onset of anaphylaxis. The minimum systolic blood pressure was inversely correlated with the severity of anaphylaxis. The severity of anaphylaxis was positively correlated with tryptase levels immediately to 1 hour, and 2 to 4 hours after the onset of anaphylaxis. CONCLUSION: Hypotension tended to reflect the severity of anaphylaxis. Tryptase is an adjunct in the diagnosis of hypotension and may be a useful indicator of the severity of anaphylaxis. A larger-scale study is needed to validate these results.

Interactive effects of exercise intensity and recovery posture on postexercise hypotension.

Postexercise reduction in blood pressure, termed postexercise hypotension (PEH), is relevant for both acute and chronic health reasons and potentially for peripheral cardiovascular adaptations. We investigated the interactive effects of exercise intensity and recovery postures (seated, supine, and standing) on PEH. Thirteen normotensive men underwent a V̇o2max test on a cycle ergometer and five exhaustive constant load trials to determine critical power (CP) and the gas exchange threshold (GET). Subsequently, work-matched exercise trials were performed at two discrete exercise intensities (10% > CP and 10% < GET), with 1 h of recovery in each of the three postures. For both exercise intensities, standing posture resulted in a more substantial PEH (all P < 0.01). For both standing and seated recovery postures, the higher exercise intensity led to larger reductions in systolic [standing: -33 (11) vs. -21 (8) mmHg; seated: -34 (32) vs. -17 (37) mmHg, P < 0.01], diastolic [standing: -18 (7) vs. -8 (5) mmHg; seated: -10 (10) vs. -1 (4) mmHg, P < 0.01], and mean arterial pressures [-13 (8) vs. -2 (4) mmHg, P < 0.01], whereas in the supine recovery posture, the reduction in diastolic [-9 (9) vs. -4 (3) mmHg, P = 0.08) and mean arterial pressures [-7 (5) vs. -3 (4) mmHg, P = 0.06] was not consistently affected by prior exercise intensity. PEH is more pronounced during recovery from exercise performed above CP versus below GET. However, the effect of exercise intensity on PEH is largely abolished when recovery is performed in the supine posture.NEW & NOTEWORTHY The magnitude of postexercise hypotension is greater following the intensity above the critical power in a standing position.