Can Early Warning Systems Enhance Detection of High Risk Patients by Rapid Response Teams?

PURPOSE: We sought to evaluate if incorporating an early warning system (EWS), the Visensia Safety Index (VSI) and the National Early Warning Systems 2 (NEWS2), may lead to earlier identification of rapid response team (RRT) patients. METHODS: This was a retrospective study (2015-2018) of patients experiencing RRT activation within a tertiary care network. We evaluated the proportion of patients with an EWS alert prior to RRT activation and their associated outcomes (primary: hospital mortality). RESULTS: There were 6,346 RRT activations over the study period. Of these, 2042 (50.8%) patients would have had a VSI alert prior to RRT activation, with a median advanced time of 3.6 (IQR 0.5-12.8) hours, compared to 2351 (58.4%) patients and 9.8 (IQR 2.0-18.7) hours for NEWS2. Patients with a potential alert prior to RRT activation had an increased odds of mortality for both VSI (OR 1.2, 95%CI 1.1-1.3) and NEWS2 (OR 2.7, 95% CI 2.4-3.1). Prognostic accuracy for hospital mortality was similar between groups. CONCLUSION: Utilization of an EWS by an RRT has potential to provide earlier recognition of deterioration and mortality risk among hospitalized inpatients.

A fundamental relationship between intraventricular conduction and heart rate.

BACKGROUND: Existence of a relationship between the electrocardiographic QRS interval duration and the diurnally varying heart rate, of consistent sign and magnitude, is controversial and the relationship has not been fully characterized in normal populations. METHODS AND RESULTS: We analyzed the QRS-RR interval relationship in 884 Holter recordings in 410 normal subjects participating in 5 clinical trials. The slope of the linear regression of QRS on RR was positive in 93% of subjects with an average slope of 0.0125, which indicates an increase in QRS duration of 1.25msec for an increase in RR interval of 100msec. The increase was 15% larger in women than in men. Age had no significant effect on the slope. CONCLUSIONS: In two populations of normal subjects we observed a robust, direct relationship between the spontaneously changing RR interval and intraventricular conduction time represented by the duration of the QRS interval. As heart rate increases, QRS duration decreases. The change is larger in women. These observations have important physiological and clinical implications.

Automated QT analysis that learns from cardiologist annotations.

BACKGROUND: Reliable, automated QT analysis would allow the use of all the ECG data recorded during continuous Holter monitoring, rather than just intermittent 10-second ECGs. METHODS: BioQT is an automated ECG analysis system based on a Hidden Markov Model, which is trained to segment ECG signals using a database of thousands of annotated waveforms. Each sample of the ECG signal is encoded by its wavelet transform coefficients. BioQT also produces a confidence measure which can be used to identify unreliable segmentations. The automatic generation of templates based on shape descriptors allows an entire 24 hours of QT data to be rapidly reviewed by a human expert, after which the template annotations can automatically be applied to all beats in the recording. RESULTS: The BioQT software has been used to show that drug-related perturbation of the T wave is greater in subjects receiving sotalol than in those receiving moxifloxacin. Chronological dissociation of T-wave morphology changes from the QT prolonging effect of the drug was observed with sotalol. In a definitive QT study, the percentage increase of standard deviation of QT(c) for the standard manual method with respect to that obtained with BioQT analysis was shown to be 44% and 30% for the placebo and moxifloxacin treatments, respectively. CONCLUSIONS: BioQT provides fully automated analysis, with confidence values for self-checking, on very large data sets such as Holter recordings. Automatic templating and expert reannotation of a small number of templates lead to a reduction in the sample size requirements for definitive QT studies.