Six methods to determine expiratory time constants in mechanically ventilated patients: a prospective observational physiology study.

Background: Expiratory time constant (τ) objectively assesses the speed of exhalation and can guide adjustments of the respiratory rate and the I:E ratio with the goal of achieving complete exhalation. Multiple methods of obtaining τ are available, but they have not been compared. The purpose of this study was to compare six different methods to obtain τ and to test if the exponentially decaying flow corresponds to the measured time constants.

Development and evaluation of a mechanical ventilator-sharing system.

Background: During the COVID-19 pandemic surge in the hospitalization of critically ill patients and the global demand for mechanical ventilators, alternative strategies for device sharing were explored. We developed and assessed the performance of a system for shared ventilation that uses clinically available components to individualize tidal volumes under a variety of clinically relevant conditions. The feasibility of remote monitoring of ventilators was also assessed.

Effect of transcutaneous cervical vagus nerve stimulation on declarative and working memory in patients with Posttraumatic Stress Disorder (PTSD): A pilot study.

Background: Posttraumatic stress disorder (PTSD) is associated with changes in multiple neurophysiological systems, including verbal declarative memory deficits. Vagus Nerve Stimulation (VNS) has been shown in preliminary studies to enhance function when paired with cognitive and motor tasks. The purpose of this study was to analyze the effect of transcutaneous cervical VNS (tcVNS) on attention, declarative and working memory in PTSD patients.

Time constant to determine PEEP levels in mechanically ventilated COVID-19 ARDS: a feasibility study.

Background: We hypothesized that the measured expiratory time constant (TauE) could be a bedside parameter for the evaluation of positive end-expiratory pressure (PEEP) settings in mechanically ventilated COVID-19 patients during pressure-controlled ventilation (PCV).

Methods: A prospective study was conducted including consecutively admitted adults (n = 16) with COVID-19-related ARDS requiring mechanical ventilation. A PEEP titration using PCV with a fixed driving pressure of 14 cmHO was performed and TauE recorded at each PEEP level (0 to 18 cmHO) in prone (n = 29) or supine (n = 24) positions.

Use of a Portable Electronic Interface Improves Clinical Handoffs and Adherence to Lung Protective Ventilation.

Background: Mechanical ventilation (MV) is used to support patients with respiratory impairment. Evidence supports the use of lung-protective ventilation (LPV) during MV to improve outcomes. However, studies have demonstrated poor adherence to LPV guidelines.

Patients alter power of breathing as the primary response to changes in pressure support ventilation.

Introduction: The patient-ventilator relationship is dynamic as the patient's health fluctuates and the ventilator settings are modified. Spontaneously breathing patients respond to mechanical ventilation by changing their patterns of breathing. This study measured the physiologic response when pressure support (PS) settings were modified during mechanical ventilation.

Clinical decision support recommending ventilator settings during noninvasive ventilation.

NIV therapy is used to provide positive pressure ventilation for patients. There are protocols describing what ventilator settings to use to initialize NIV; however, the guidelines for titrating ventilator settings are less specific. We developed an advisory system to recommend NIV ventilator setting titration and recorded respiratory therapist agreement rates at the bedside.

Breathing variability predicts the suggested need for corrective intervention due to the perceived severity of patient-ventilator asynchrony during NIV.

Patient-ventilator asynchrony is associated with intolerance to noninvasive ventilation (NIV) and worsened outcomes. Our goal was to develop a tool to determine a patient needs for  intervention by a practitioner due to the presence of patient-ventilator asynchrony. We postulated that a clinician can determine when a patient needs corrective intervention due to the perceived severity of patient-ventilator asynchrony.

Evaluating Fundal Dominant Contractions on Spatiotemporal Electrohysterography as a Marker for Effective Labor Contractions.

Objective: To evaluate if fundal (F) dominance of the electrohysterogram is associated with vaginal delivery and lack of F dominance is associated with cesarean for labor dystocia.

Study Design: We conducted a prospective cohort study of nulliparous women in spontaneous labor at ≥36 weeks. Clinicians were blinded to electrohysterography data which were in addition to standard cardiotocography.

Photoplethysmography and Heart Rate Variability for the Diagnosis of Preeclampsia.

Background: The goal of this study was to determine a set of timing, shape, and statistical features available through noninvasive monitoring of maternal electrocardiogram and photoplethysmography that identifies preeclamptic patients.

Methods: Pregnant women admitted to Labor and Delivery were monitored with pulse oximetry and electrocardiogram for 30 minutes. Photoplethysmogram features and heart rate variability were extracted from each data set and applied to a sequential feature selection algorithm to discriminate women with preeclampsia with severe features, from normotensive and hypertensive controls.

Decision support system facilitates rapid decreases in pressure support and appropriate inspiratory muscle workloads in adults with respiratory failure.

Purpose: A commercially available decision support system (DSS) provides guidance for setting inspiratory pressure support (PS) to maintain work of breathing (WOB/min), breathing frequency (f), and tidal volume (V) in proper clinical ranges (VentAssist™). If these values are outside the proper clinical range patients may suffer fatigue, atrophy, hypoventilation, hyperventilation, volutrauma, or V deficiency. The purpose of our study was to evaluate the increase of the percentage of breaths in the targeted clinical ranges when the DSS guidance for setting the PS was followed.

Monitoring Fetal Heart Rate during Labor: A Comparison of Three Methods.

The purpose of the study was to compare the accuracy of a noninvasive fetal heart rate monitor with that of ultrasound, using a fetal scalp electrode as the gold standard, in laboring women of varying body habitus, throughout labor and delivery. Laboring women requiring fetal scalp electrode were monitored simultaneously with the investigational device (noninvasive fetal ECG), ultrasound, and fetal scalp electrode. An algorithm extracted the fetal heart rate from the noninvasive fetal ECG signal.

Performance, Reliability, Usability, and Safety of the ID-Cap System for Ingestion Event Monitoring in Healthy Volunteers: A Pilot Study.

Nonadherence to prescribed medications is an important consideration in the clinical management of patients and in clinical research and drug development. The ID-Cap System is a novel technology that provides an objective measure of medication ingestion and enables real-time reporting of verified medication adherence data at the dose level. The ID-Cap System consists of an ingestible microsensor that is embedded in an oral dosage form and, once activated by stomach fluid, communicates digital messages to an external wearable reader to confirm ingestion.

Monitoring Uterine Activity during Labor: Clinician Interpretation of Electrohysterography versus Intrauterine Pressure Catheter and Tocodynamometry.

Objective The aim of this article was to compare clinical interpretation of uterine activity tracings acquired by tocodynamometry and electrohysterography with the gold standard, intrauterine pressure. Study Design Using data from a previous study, subjects who had simultaneous monitoring with all three uterine activity devices were included in this study. These were parturients who required intrauterine pressure catheter (IUPC) placement for obstetric indication.

Creating clinical decision support systems for respiratory medicine.

Clinical decision support systems are vital for advances in improving patient therapeutic care. We share lessons learned from creating two respiratory clinical decisions support systems for ventilating patients in a critical care setting.

Real time noninvasive estimation of work of breathing using facemask leak-corrected tidal volume during noninvasive pressure support: validation study.

We describe a real time, noninvasive method of estimating work of breathing (esophageal balloon not required) during noninvasive pressure support (PS) that uses an artificial neural network (ANN) combined with a leak correction (LC) algorithm, programmed to ignore asynchronous breaths, that corrects for differences in inhaled and exhaled tidal volume (VT) from facemask leaks (WOBANN,LC/min). Validation studies of WOBANN,LC/min were performed. Using a dedicated and popular noninvasive ventilation ventilator (V60, Philips), in vitro studies using PS (5 and 10 cm H2O) at various inspiratory flow rate demands were simulated with a lung model.

Oxygenation advisor recommends appropriate positive end expiratory pressure and FIO2 settings: retrospective validation study.

A decision support, rule-based oxygenation advisor that provides guidance for setting positive end expiratory pressure (PEEP) and fractional inhaled oxygen concentration (FIO2) for patients with respiratory failure is described. The target oxygenation goal is to achieve and maintain pulse oximeter oxygen saturation (SpO2) ≥ 88 and ≤ 95%, as posited by the Acute Respiratory Distress Syndrome Network, by recommending appropriate combinations of PEEP and FIO2. For patient safety, the oxygenation advisor monitors mean arterial blood pressure (MAP) to ensure it is ≥ 65 mmHg for hemodynamic stability and inspiratory plateau pressure (Pplt) so it is ≤ 30 cm H2O for lung protection.

Expiratory time constant for determinations of plateau pressure, respiratory system compliance, and total resistance.

Introduction: We hypothesized the expiratory time constant (ƬE) may be used to provide real time determinations of inspiratory plateau pressure (Pplt), respiratory system compliance (Crs), and total resistance (respiratory system resistance plus series resistance of endotracheal tube) (Rtot) of patients with respiratory failure using various modes of ventilatory support.

Methods: Adults (n = 92) with acute respiratory failure were categorized into four groups depending on the mode of ventilatory support ordered by attending physicians, i.e.

Monitoring uterine activity during labor: a comparison of 3 methods.

Objective: Tocodynamometry (Toco; strain gauge technology) provides contraction frequency and approximate duration of labor contractions but suffers frequent signal dropout, necessitating repositioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen.

Noninvasive work of breathing improves prediction of post-extubation outcome.

Purpose: We hypothesized that non-invasively determined work of breathing per minute (WOB(N)/min) (esophageal balloon not required) may be useful for predicting extubation outcome, i.e., appropriate work of breathing values may be associated with extubation success, while inappropriately increased values may be associated with failure.

Pressure support ventilation advisory system provides valid recommendations for setting ventilator.

Background: Pressure support ventilation (PSV) should be applied so that the inspiratory muscles are unloaded appropriately. We developed a computerized advisory system that assesses the load on the inspiratory muscles to spontaneously inhale, reflected by the automatically and noninvasively measured work of breathing per minute, and tolerance for that load, reflected by spontaneous breathing frequency and tidal volume, in a fuzzy-logic algorithm that provides recommendations for setting PSV. We call this a load and tolerance strategy for determining PSV.

Spatiotemporal electrohysterography patterns in normal and arrested labor.

Objective: The purpose of this study was to investigate the spatiotemporal patterns of uterine electrical activity in normal and arrested labors.

Study Design: From a database of electrohysterograms, 12 subjects who underwent cesarean delivery for active-phase arrest were each matched with 2 vaginally delivered controls. Using 30-minute segments of the electrohysterogram during the arrest, or the same dilation in controls, the center of uterine electrical activity was derived.

Ventilator advisory system employing load and tolerance strategy recommends appropriate pressure support ventilation settings: multisite validation study.

Background: Loads on the respiratory muscles, reflected by noninvasive measurement of the real-time power of breathing (POBn), and tolerance of these loads, reflected by spontaneous breathing frequency (f) and tidal volume (Vt), should be considered when evaluating patients with respiratory failure. Pressure support ventilation (PSV) should be applied so that muscle loads are not too high or too low. We propose a computerized, ventilator advisory system employing a load (POBn) and tolerance (f and Vt) strategy in a fuzzy logic algorithm to provide guidance for setting PSV.