Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace (Protocol)

This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the effectiveness and risks of fetal scalp lactate sampling in the assessment of fetal wellbeing during labour, compared with no testing or alternative additional testing (pH, fetal pulse oximetry, etc) for women exhibiting a non-reassuring cardiotocograph trace. A secondary objective of the review is to determine whether effectiveness and risks of intrapartum fetal scalp lactate sampling is influenced by the following: stage of labour; gestation less than 37 completed weeks, greater than or equal to 37 completed weeks; additional tests performed to confirm the presence or absence of fetal acidemia during labour.

Response of heart rate and cloacal ventilation in the bimodally respiring freshwater turtle, Rheodytes leukops to experimental changes in aquatic PO2

Changes in heart rate (f(H)) and cloacal ventilation frequency (f(C)) were investigated in the Fitzroy turtle, Rheodytes leukops, under normoxic (17.85 kPa) and hypoxic (3.79 kPa) conditions at 25 degrees C. Given R. leukops' high reliance on aquatic respiration via the cloacal bursae, the objective Of this Study was to examine the effect of varying aquatic PO2 levels upon the expression of a bradycardia in a freely diving, bimodally respiring turtle. In normoxia, mean diving f(H) and f(C) for R. leukops remained constant with increasing submergence length, indicating that a bradycardia failed to develop during extended dives of up to 3 days. Alternatively, exposure to aquatic hypoxia resulted in the expression of a bradycardia as recorded by a decreasing mean diving f(H) with increasing dive duration. The observed bradycardia is attributed to a hypoxic-induced metabolic depression, possibly facilitated by a concurrent decrease in f(C). Results suggest that R. leukops alters its strategy from aquatic O-2 extraction via cloacal respiration in normoxia to O-2 conservation when exposed to aquatic hypoxia for the purpose of extending dive duration. Upon surfacing, a significant tachycardia was observed for R. leukops regardless of aquatic PO2, presumably functioning to rapidly equilibrate blood and tissue gas tensions with alveolar gas to reduce surfacing duration.

Variability in heart rate estimates from different pulse oximeters

Since its introduction, pulse oximetry has become a conventional clinical measure. Besides being arterial blood oxygen saturation (SpO2) measure, pulse oximeters can be used for other cardiovascular measurements, like heart rate (HR) estimations, derived from its photo plethysmographic (PPG) signals. The temporal coherence of the PPG signals and thereby HR estimates are heavily dependent on its minimal phase variability. A Masimo SET Rad-9TM, Novametrix Oxypleth and a custom designed PPG system were investigated for their relative phase variation. R-R intervals from electro-cardiogram (ECG) were recorded concurrently as reference. PPG signals obtained from the 3 systems were evaluated by comparing their respective beat-to-beat (B-B) intervals with the corresponding R-R estimates during a static test. For their relative B-B comparison to the ECG, Novametrix system differed 0.680.52% (p

Heart rate variability characterization using a time-frequency based instantaneous frequency estimation technique

In this paper, a new method for characterizing the newborn heart rate variability (HRV) is proposed. The central of the method is the newly proposed technique for instantaneous frequency (IF) estimation specifically designed for nonstationary multicomponen signals such as HRV. The new method attempts to characterize the newborn HRV using features extracted from the time–frequency (TF) domain of the signal. These features comprise the IF, the instantaneous bandwidth (IB) and instantaneous energy (IE) of the different TF components of the HRV. Applied to the HRV of both normal and seizure suffering newborns, this method clearly reveals the locations of the spectral peaks and their time-varying nature. The total energy of HRV components, ET and ratio of energy concentrated in the low-frequency (LF) to that in high frequency (HF) components have been shown to be significant features in identifying the HRV of newborn with seizures.

Time-Frequency Distribution Moments of Heart Rate Variability for Neonatal Seizure Detection

In this paper, we propose features extracted from the heart rate variability (HRV) based on the first and second conditional moments of time-frequency distribution (TFD) as an additional guide for seizure detection in newborn. The features of HRV in the low frequency band (LF: 0-0.07 Hz), mid frequency band (MF: 0.07-0.15 Hz), and high frequency band (HF: 0.15-0.6 Hz) have been obtained by means of the time-frequency analysis using the modified-B distribution (MBD). Results of ongoing time-frequency research are presented. Based on our preliminary results, the first conditional moment of HRV which is also known as the mean/central frequency in the LF band and the second conditional moment of HRV which is also known as the variance/instantaneous bandwidth (IB) in the HF band can be used as a good feature to discriminate the newborn seizure from the non-seizure

Changes in heart rate variability associated with moderate alcohol consumption

Technological advances have driven some attempt of vital parameters monitoring in adverse environments; these improvements will make possible to monitor cardiac activity also in automotive environments. In this scenario, heart rate changes associated with alcohol consumption, become of great importance to assess the drivers state during time. This paper presents the results of a first set of experiments aimed to discover heart rate variability modification induced by moderate assumption of alcoholic drink (i.e. single draft beer) as that typically occurs in weekend among some people. In the study, twenty subjects were enrolled and for each of them two electrocardiographic recordings were carried out: the first before alcohol ingestion and the second after 25-30 minutes. Each participant remained fasting until the second ECG acquisition was completed. ECG signal were analyzed by typical timedomain, frequency and non linear analysis. Results showed a small increase in LF/HF ratio which reflects a dominance of the sympathetic system over the parasympathetic system, and an increase in signal complexity as proven by non linear analysis. However, the study highlighted the need to monitor HRV starting from alcohol ingestion until its complete metabolization to allow a more precise description of its variation. © Springer International Publishing Switzerland 2014.