Functional testers are designed to evaluate select pulse oximeter characteristics but are often misused to validate device accuracy, potentially providing false reassurance. This study evaluated whether the Fluke ProSim8 (FPS8) could accurately predict oximeter performance during human controlled desaturation studies or identify performance differences under low signal conditions. 12 oximeters were tested using two FPS8 protocols: (1) an 'SpO₂ plateau' protocol which mimicked controlled desaturation studies by evaluating device performance over a range of simulated SpO2 (70-100%), and (2) a 'signal space' protocol designed to assess device accuracy under varying modulation and transmission conditions. Each device also underwent controlled desaturation testing in healthy adults.Six of the 12 oximeters passed (ARMS ≤ 3%) the SpO₂ plateau protocol; however, three of these failed (ARMS > 3%) human testing. At lower simulated saturations, most devices overestimated SpO₂. In the signal space protocol, oximeters performed well under high signal conditions, but many failed to produce readings or showed SpO₂ errors > 3% under low signal conditions. On average, oximeters failed to generate a reading 20.2 ± 7.2 times out of 60 attempts. Ten devices passed (ARMS < 3%) the signal space protocol, but two of these failed human testing. Oximeter performance on the FPS8 did not correlate with human performance (R² = 0.08 for the plateau protocol; R² = 0.01 for the signal space protocol).The FPS8 did not reliably predict oximeter accuracy in human desaturation studies or under low signal conditions; current functional tester protocols are limited in predicting real-world oximeter performance.

Changes in lung and pleural pressures during mechanical ventilation are transmitted to intrathoracic structures, including the venous system. As a result, respiratory swings in central venous pressure (CVP) may reflect variations in pleural pressure, typically estimated using esophageal pressure (Pes). However, the point on the CVP waveform used for measurement may influence this relationship. Our aim is to find the best association between ∆Pes and each ∆CVP considering different points in the CVP waveform to calculate ∆CVP. In this prospective study, we analysed CVP and Pes waveforms in 22 mechanically ventilated patients. For each cardiac cycle, three CVP values were identified: the minimum (CVPmin), the maximum (CVPmax), and the average (CVPavg). From these, four types of respiratory CVP variation (∆CVP) were calculated per breath: ∆CVPmin = max-min of CVPmin values; ∆CVPmax = max-min of CVPmax values; ∆CVPavg = max-min of CVPavg values; ∆CVPtot = absolute difference between the highest CVPmax and the lowest CVPmin within each respiratory cycle. The primary objective was to assess the association between ∆Pes and each ∆CVP variant using linear mixed-effects models. A total of 2,286 breaths (median 104 per patient) was analysed. All ∆CVP measures showed a statistically significant association with ∆Pes. The strongest correlation was observed for ∆CVPtot, with a marginal R² of 0.50 and a conditional R² of 0.78. The association further improved when using the median of multiple consecutive breaths. Specifically, the marginal R² increased from 0.60 (median of 3 breaths) to 0.70 (median of 23 breaths). Among the different measurement strategies, ∆CVPtot—defined as the difference between the highest and lowest CVP values within a respiratory cycle—showed the strongest association with ∆Pes. Averaging over at least three consecutive breaths further enhanced this relationship. These data are useful for understanding how ∆CVP can be used to estimate ∆Pes at the bedside.

Quantitative neuromuscular monitoring (NMM) is widely recommended, yet its clinical adoption remains limited, partly due to usability issues. This study aimed to compare the clinical performance of two electromyography (EMG)-based NMM devices—the Datex-Ohmeda E-NMT module and the Stimpod NMS450X—under real-world operating room conditions. Twenty-four adult patients undergoing elective non-cardiac surgery were monitored simultaneously with both devices, applied contralaterally. Train-of-four (TOF) counts and TOF ratios were recorded at one-minute intervals. Agreement between devices was assessed using Bland–Altman analysis, repeatability coefficients, and the concordance correlation coefficient (CCC). The Datex-Ohmeda recorded an average of 121 TOF-count and 71 TOF-ratio values per patient, compared with 56 and 39, respectively, for the Stimpod. Inter-device correspondence was low, with numerous missing or physiologically implausible values on the Stimpod stream. The repeatability coefficient was 0.81 (95% CI: 0.80–0.83), indicating poor precision. The CCC was 0.662, consistent with weak agreement. In routine clinical use, the Stimpod NMS450X and Datex-Ohmeda E-NMT demonstrated poor concordance and high variability, likelyinfluenced by device-specific artifacts, connectivity limitations and electrode sensitivity.These findings highlight the need for device-specific validation of EMG NMM, both for clinical practice and for research purposes.

Despite the substantial advancements in mechanical ventilation (MV), mortality remains high. Mechanical power (MP), MV forces are associated with outcomes. Real-time monitoring of MP and the adjustment of MV according to MP may result in ventilation with lower MP. Randomized controled trial conducted at the ECMO Centre Ostrava, Czech Republic, from March 2023 to March 2024 enrolled adult patients on MV (with or without extracorporeal membrane oxygenation, ECMO) with acute respiratory failure. A system for real-time MP monitoring (geometric method and simplified Becher´s formula) has been developed. In the intervention arm, the physician was able to observe the MP in real time and adjust the MV parameters accordingly. In the control group, the MP was concealed. A total of 494 subjects were screened and 33 patients were randomized (further 7 ECMO patients). There was no significant difference between the control and intervention groups. Median MPGeom was 3.22J/min (maximum 15.2J/min) and MPBecher of 5.94J/min (maximum 18.4J/min). Only a weak (but significant, p = 0.0001) correlation between MPGeom and MPBecher was observed. A highly significant difference was observed in MP between day and night (6 a.m. - 6 p.m.) with higher MP at night. Although real-time MP measurement is feasible, there was no significant difference in MP between the control and intervention groups with low MP in both groups. Experience physicians was capable of safe MV, even if they do not know the exact MP value. The night shift was a high-risk period for developing lung damage due to elevated MP. ClinicalTrials NCT06035146.

This retrospective cohort study aimed to investigate the association between intraoperative hypotension (IOH) and postoperative acute kidney injury (AKI) among patients who underwent emergent critical cesarean delivery. We analyzed electronic health records from January 2019 to August 2024. IOH was defined as a mean arterial pressure (MAP) less than 65 mmHg. It was quantified using four metrics: hypotensive event count, cumulative duration, area under the threshold (AUC), and time-weighted average (TWA). Postoperative AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guidelines, based on serum creatinine levels. We employed multivariable logistic regression to assess the independent association between the primary IOH metric (cumulative duration) and postoperative AKI, adjusting for clinically relevant covariates. Sensitivity analyses were conducted using alternative IOH metrics. Postoperative AKI was diagnosed in 69 of the 508 patients (13.58%). Multivariable logistic regression analysis revealed that all four measures of intraoperative hypotension were independently associated with an increased risk of AKI: hypotensive event count (adjusted OR 2.098, 95%CI [1.180-3.732]; P = 0.012), cumulative duration (adjusted OR 1.036, 95%CI [1.013-1.060]; P = 0.002), AUC (adjusted OR 1.004, 95%CI [1.001-1.007]; P = 0.009), and TWA (adjusted OR 1.557, 95%CI [1.058-2.291]; P = 0.025). Our findings demonstrate that IOH was independently associated with a higher incidence of postoperative AKI in patients who underwent an emergent critical cesarean delivery.

Vegetative reactions are common during neurosurgical procedures. Known effects are mainly cardiovascular, including tachy- and bradyarrhythmia, hyper- and hypotonia as well as cardiac arrest. Computer-assisted real-time analysis of heart rate variability (HRV), baroreflex-sensitivity (BRS) allows for continuous evaluation of the autonomic nervous system (ANS). We analyzed ANS parameters during intracranial neurosurgical procedures. In this pilot study, we aim to provide proof-of-concept that ANS monitoring during surgery is feasible and yields stable results.We included 129 consecutive patients undergoing neurosurgery for intracranial pathologies over a period of four months. Heart rate (HR) and mean arterial pressure (MAP) were continuously monitored during routine anesthesiology care. Data were recorded via ICM + software. HRV, BRS and other vegetative parameters were calculated continuously. Intraoperative events such as hypo-/hypertonia or brady-/tachycardia were monitored.Mean age was 47.2 ± 17.7 years. Of all patients, 54.3% were male (n = 70). For every patient, four intraoperative episodes were defined: start of anesthesia until incision - start of incision until craniotomy - craniotomy until end of resection or intracranial manipulation - end phase until skin closure. BRS continuously decreased during cranial surgery, indicating stabilized autonomic function. Furthermore, blood pressure variability was increased during semi-sitting surgery.Autonomic system monitoring during neurosurgical procedures is safe and feasible. Intraoperatively, an increasing sympathetic activity has been observed without clear disctinction between surgical or anesthesiological events as underlying cause. Monitoring results are reproducible and may be of importance for the detection and prevention of intraoperative cardiovascular events.

Stroke volume variation (SVV) is a dynamic parameter used to assess fluid responsiveness in mechanically ventilated patients. This study aimed to evaluate the agreement and trending ability of SVV measurements obtained from bioreactance (Starling SV) and arterial waveform analysis devices (FloTrac and LiDCOrapid) during cardiac surgery. This prospective observational method comparison study was conducted in a single university hospital. 18 patients undergoing off-pump coronary artery bypass grafting (OPCAB) were monitored with Starling SV and FloTrac. 20 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) were monitored with Starling SV and LiDCOrapid. SVV measurements were collected intraoperatively and postoperatively. Agreement and trending ability between devices were assessed using Bland-Altman analysis and four-quadrant plots with error grids and concordance analysis. A total of 2055 paired SVV measurements were obtained in the OPCAB group and 367 in the CPB group. The mean bias between Starling SV and FloTrac was 2.3%pt (95% CI 2.1 to 2.6) with wide limits of agreement (-14.3 to 20.5%pt). For Starling SV and LiDCOrapid, the bias was 1.5%pt (95% CI 0.9 to 2.2) with very wide limits of agreement (-38.3 to 38.4%pt). Trending ability was poor in all comparisons. Despite acceptable mean biases, the variability between devices was considerable, and trending analyses indicated only limited concordance. The studied SVV monitors, therefore, cannot be considered interchangeable in the context of cardiac surgery. These findings highlight the limitations and uncertainty of SVV monitoring in this setting.

Capillary refill time (CRT) is a vaso-occlusive test that allows the non-invasive assessment of skin perfusion. A vascular occlusive test (VOT) induces transient ischemia similar to that used in preconditioning ischemia. We hypothesized that CRT could be influenced by local tissue compression mimicking ischemic preconditioning when repeated measurements are performed. In healthy volunteers (n = 30), CRTs were performed twice on the index and middle fingers of the dominant hand and the index finger of the non-dominant hand at 15-minute intervals on the first day. On the second day, two CRT measurements were taken at 30-minute intervals. No significant differences were observed in CRT measurements repeated at 15- and 30-minute intervals. Additionally, baseline CRT values did not significantly differ between the fingers of the dominant and non-dominant hands on either study day. Repeated CRT measurements are not influenced by local ischemic preconditioning in the finger over short intervals.

To evaluate the inter- and intraobserver reproducibility of sublingual microcirculatory indices measured using the GlycoCheck system, including the perfused boundary region (PBR), vascular density (VD), and red blood cell filling (RBCF), in patients under general anesthesia without any motion artifacts. Fifty patients who received general anesthesia for laparoscopic gastrointestinal surgery were included in this study. After the induction of general anesthesia, the leading observer and one of the five subobservers took two and one measurements of sublingual microcirculation with the GlycoCheck system, respectively. Inter- and intraobserver reproducibility was assessed using intraclass correlation coefficients (ICC). Interobserver reproducibility was calculated using the first measurements of the leading observer and subobservers, and intraobserver reproducibility was calculated using two consecutive measurements of the leading observer. The interobserver reproducibility of a single measurement was poor for all three parameters. The interobserver ICCs for PBR were 0.13 [95% CI: -0.15, 0.39], for VD was - 0.01 [95%CI: -0.29, 0.27], and for RBCF were 0.31 [95%CI: -0.45, 0.78]. The intraobserver ICCs for PBR was 0.32 [95% CI: 0.05, 0.55] for all 50 cases, 0.17 [95% CI: -0.25, 0.53] for the first 25 cases, and 0.46 [95% CI: 0.09, 0.72] for the second 25 cases. The Bland-Altman plots indicated that the measurement errors were random. In patients under general anesthesia, single PBR, VD, and RBCF measurements using the GlycoCheck system showed poor interobserver reproducibility. Although the intraobserver reproducibility of PBR measurements was poor, improving measurement proficiency might improve reproducibility. Further research is required to establish measurement methods that achieve better reproducibility and adequate observer training.