A Guide to Measuring Heart and Respiratory Rates Based on Off-the-Shelf Photoplethysmographic Hardware and Open-Source Software.

The remote monitoring of vital signs via wearable devices holds significant potential for alleviating the strain on hospital resources and elder-care facilities. Among the various techniques available, photoplethysmography stands out as particularly promising for assessing vital signs such as heart rate, respiratory rate, oxygen saturation, and blood pressure. Despite the efficacy of this method, many commercially available wearables, bearing Conformité Européenne marks and the approval of the Food and Drug Administration, are often integrated within proprietary, closed data ecosystems and are very expensive. In an effort to democratize access to affordable wearable devices, our research endeavored to develop an open-source photoplethysmographic sensor utilizing off-the-shelf hardware and open-source software components. The primary aim of this investigation was to ascertain whether the combination of off-the-shelf hardware components and open-source software yielded vital-sign measurements (specifically heart rate and respiratory rate) comparable to those obtained from more expensive, commercially endorsed medical devices. Conducted as a prospective, single-center study, the research involved the assessment of fifteen participants for three minutes in four distinct positions, supine, seated, standing, and walking in place. The sensor consisted of four PulseSensors measuring photoplethysmographic signals with green light in reflection mode. Subsequent signal processing utilized various open-source Python packages. The heart rate assessment involved the comparison of three distinct methodologies, while the respiratory rate analysis entailed the evaluation of fifteen different algorithmic combinations. For one-minute average heart rates' determination, the Neurokit process pipeline achieved the best results in a seated position with a Spearman's coefficient of 0.9 and a mean difference of 0.59 BPM. For the respiratory rate, the combined utilization of Neurokit and Charlton algorithms yielded the most favorable outcomes with a Spearman's coefficient of 0.82 and a mean difference of 1.90 BrPM. This research found that off-the-shelf components are able to produce comparable results for heart and respiratory rates to those of commercial and approved medical wearables.

Effect of Perioperative Oral Vitamin C Supplementation on In-Hospital Postoperative Medication Costs for Cardiac Surgery Patients: A Prospective, Single-Centre, Randomised Clinical Trial.

BACKGROUND: Due to its antioxidant properties, vitamin C might be a promising and effective strategy for preventing postoperative atrial fibrillation (POAF) after cardiac surgery. This study was aimed at evaluating whether vitamin C supplementation is effective in reducing the cost of in-hospital postoperative medication used for patients undergoing coronary artery bypass (CABG) or valve surgery (±CABG). OBJECTIVE: The primary goal of this study was to evaluate the impact of perioperative vitamin C supplementation in patients undergoing cardiac surgery on in-hospital postoperative medication costs, while secondary endpoints were the effects on length of stay (LOS) in both the intensive care unit (ICU) and the hospital, and the incidence of POAF. MATERIAL AND METHODS: From November 2018 to January 2021, 253 patients planned for CABG or valve surgery (±CABG) in AZ Maria Middelares, Ghent, Belgium, and who met the inclusion criteria (≥18 years of age, all having cardiac sinus rhythm, and who provided written informed consent) were randomised into a placebo group or vitamin C group. The medication was administered orally (1 g twice daily), starting from 5 days preoperatively until 10 days postoperatively. The medication used, LOS in the hospital/ICU, and development of clinically relevant POAF in the ICU were registered. RESULTS: Mean medication costs were €264.6 ± 98.1 for patients in the vitamin C group and €294.9 ± 267.3 for patients in the placebo group. When stratifying according to the type of surgery (CABG or valve surgery [±CABG]), these costs did not significantly differ. There was no significant difference in LOS or the incidence of clinically relevant POAF. CONCLUSION: Our data did not identify any short-term financial impact on postoperative medication costs after oral perioperative vitamin C supplementation (1 g twice daily) for patients undergoing a CABG procedure or valve surgery (±CABG). No effect was found on the LOS or the incidence of clinically relevant POAF. Potential effects in the longer term, after intravenous administration of vitamin C or in other types of (cardiac) surgery, are still to be investigated. CLINICAL TRIALS REGISTRATION NUMBER: NCT03592680.

Sevoflurane consumption pattern by individual anaesthesiologists varies widely despite using the same high-end workstations in the same hospital.

Volatile anaesthetics are potent greenhouse gasses but contemporary workstations enable considerable savings while improving patient safety. Institutions may provide this technology to reduce the ecological footprint but proper training and motivation is required to maximize their ecologic and financial benefit. This study aims to compare the sevoflurane consumption of 22 anaesthesiologists in a medium sized hospital 4 years after flow-i workstations (Getinge, Sweden) entered into service, in three airway approaches: intubated patients, laryngeal mask ventilation, and mask anaesthesia. Typical sevoflurane consumption for each anaesthesiologist was defined as the mean cumulative consumption in the chronologically first 50 cases meeting the inclusion criteria for each airway group in 2019. The potential savings, if everyone were to adopt the approach of the more economical anaesthesiologists (15th percentile), was calculated. The CO2 equivalent emissions were calculated using a GWP20 of 702 and a GWP100 of 195. The median [range] consumption after 45 min was 10.9 [7.5-18.4] ml in intubated patients and 9.0 [7.4-15.3] ml in patients with laryngeal mask, and 9.9 [3.4-20.9] ml after 8 min with mask ventilation. This corresponds to a double to six fold consumption between the least and most wasteful approach. The typical CO2 equivalent emissions (GWP20) per anaesthesiologist varied between 8.0 and 19.6 kg/45 min in intubated airways, between 7.9 and 16.3 kg/45 min in LMA, and between 3.6 and 22.3 kg/8 min in mask ventilation. Despite using the same workstations in the same hospital, the typical sevoflurane consumption differed dramatically between 22 anaesthesiologists. In addition to providing advanced workstations, proper education is required to achieve the behavior change needed to reduce the pollution and financial waste associated with volatile anaesthetics.

Echocardiographic assessment of aortic elastic properties with automated border detection in an ICU: in vivo application of the arctangent Langewouters model.

We studied whether combined pressure and transesophageal ultrasound monitoring is feasible in the intensive care unit (ICU) setting for global cardiovascular hemodynamic monitoring [systemic vascular resistance (SVR) and total arterial compliance (C(PPM))] and direct estimation of local ascending and descending aortic mechanical properties, i.e., distensibility and compliance coefficients (DC and CC). Pressure-area data were fitted to the arctangent Langewouters model, with aortic cross-sectional area obtained via automated border detection. Data were measured in 19 subjects at baseline, during infusion of sodium nitroprusside (SNP), and after washout. SNP infusion lowered SVR from 1.15 +/- 0.40 to 0.80 +/- 0.32 mmHg.ml(-1).s (P < 0.05), whereas C(PPM) increased from 0.87 +/- 0.46 to 1.02 +/- 0.42 ml/mmHg (P < 0.05). DC and CC increased from 0.0018 +/- 0.0007 to 0.0025 +/- 0.0009 l/mmHg (P < 0.05) and from 0.0066 +/- 0.0028 to 0.0083 +/- 0.0026 cm2/mmHg (P < 0.05), respectively, at the descending, but not ascending, aorta. The Langewouters model fitted the descending aorta data reasonably well. Assessment of local mechanical properties of the human ascending aorta in a clinical setting by automated border detection remains technically challenging.

Effects of off-pump coronary surgery on the mechanics of the respiratory system, lung, and chest wall: Comparison with extracorporeal circulation.

OBJECTIVE: To compare the effects of cardiac surgery with and without extracorporeal circulation on the mechanics of the respiratory system, lung, and chest wall. We also determined the time course of those effects. DESIGN: Prospective, controlled study. SETTING: An eight-bed, cardiac-surgical intensive care unit at a university hospital. PATIENTS: Two groups of patients scheduled for elective coronary bypass surgery were studied: ten patients with extracorporeal circulation and 13 patients without extracorporeal circulation. INTERVENTIONS: Measurement of esophageal pressure after insertion of an esophageal balloon catheter to separate respiratory system mechanics into lung and chest wall components. Measurements were performed preoperatively after induction of anesthesia (control), immediately postoperatively at arrival in the intensive care unit (time 1), and after 3 hrs (time 2). In 12 of the 23 patients, measurements were also performed 6 hrs postoperatively (time 3). MEASUREMENTS AND MAIN RESULTS: No significant differences concerning demographics or surgical procedure were noticed between the two groups. Respiratory system, chest wall, and lung mechanics were obtained using the technique of rapid airway occlusion during constant-flow inflation. In both the group with and without extracorporeal circulation there was a significant increase in static and dynamic elastance of the respiratory system and lung at times 1 and 2, which tended to decrease again at time 3; chest wall elastance significantly increased at times 2 and 3 in the group without extracorporeal circulation, whereas the increase in chest wall elastance in the group with extracorporeal circulation occurred earlier (also at time 1). Additional resistance of the respiratory system and lung remained unchanged; chest wall resistance, however, significantly increased in both groups. Work of breathing significantly increased in both groups at times 1 and 2. There was a significant reduction in the Pao2/Fio2 ratio in both groups at times 2 and 3. No significant differences between the groups at any moment were noticed. CONCLUSIONS: Coronary bypass surgery with and without extracorporeal circulation results in dramatic impairment of respiratory system mechanics. Based on respiratory system mechanics, early extubation after coronary artery bypass grafting should be performed with caution, no matter whether the off-pump or cardiopulmonary bypass technique is used.