Deceleration capacity of heart rate variability as a predictor of sedation related hypotension

High risk and geriatric patients are supposed to suffer higher risks of hypotension underwent painless endoscopic procedures. This study evaluated different biomarkers associated with hypotension in off-site patients and aimed to determine the most relevant risk factors in space and monitoring limited environment. The inclusions of this observational cohort study underwent complex endoscopic procedures were sedated with age-adjusted doses of target-controlled infusion of propofol. The following pre-sedative parameters were analysed: time domain, frequency domain, and Deceleration capacity (DC) of heart rate variability, estimated cardiac output data and the index of cardiac contractility from the cardiometer. Patients were divided into hypotension group (blood pressure < 90 mmHg or a > 35% decrease) and non-hypotension group according to peri-sedative blood pressure, regression analysis is used to examine the association between factors and hypotension. Total data from 178 patients (age range: 33–94 years) were analysed. Age was not significantly different between the hypotension and non-hypotension groups (p = 0.978). Among all the factors, DC was most associated with hypotension (p = 0.05), better than cardiometer, age, and ASA status. In conclusion, DC, which can be interpreted as the indicator of parasympathetic activity and was significantly and negatively correlated with sedation-related hypotension. Pre-sedative measuring DC from routine ECG monitoring is simple and cost-effective and should be added to haemodynamic monitoring in the endoscopic room.

The Diagnostic Value of Cardiac Deceleration Capacity in Vasovagal Syncope

Background: Increased parasympathetic activity is thought to play important roles in syncope events of patients with vasovagal syncope (VVS). However, direct measurements of the vagal control are difficult. The novel deceleration capacity (DC) of heart rate measure has been used to characterize the vagal modulation. This study aimed to assess vagal control in patients with VVS and evaluate the diagnostic value of the DC in VVS. Methods: Altogether, 161 consecutive patients with VVS (43±15 years; 62 males) were enrolled. Tilt table test was positive in 101 and negative in 60 patients. Sixty-five healthy subjects were enrolled as controls. DC and heart rate variability in 24-hour ECG, echocardiogram, and biochemical examinations were compared between the syncope and control groups. Results: DC was significantly higher in the syncope group than in the control group (9.6±3.3 versus 6.5±2.0 ms, P <0.001). DC was similarly increased in patients with VVS with a positive and negative tilt table test (9.7±3.5 and 9.4±2.9 ms, P =0.614). In multivariable logistic regression analyses, DC was independently associated with syncope (odds ratio=1.518 [95% CI, 1.301–1.770]; P =0.0001). For the prediction of syncope, the area under curve analysis showed similar values when comparing single DC and combined DC with other risk factors ( P =0.1147). From the receiver operator characteristic curves for syncope discrimination, the optimal cutoff value for the DC was 7.12 ms. Conclusions: DC>7.5 ms may serve as a good tool to monitor cardiac vagal activity and discriminate VVS, particularly in those with negative tilt table test.