Loss of endotracheal cuff pressure can lead to airway compromise and loss of volume delivery in mechanical ventilation requiring immediate intervention. A 40 years old male posted for bilateral interpositional arthroplasty was intubated nasally with 7.5 mm flexometallic endotracheal tube. In the intraoperative period airway leak was detected due to loss of cuff pressure even after repeated attempt of cuff inflation. After changing endotracheal tube, leak was detected from the inflation tubing distal to the cuff, which was apparent only when cuff pressure was increased above 30 cm of H2O.

Postoperative hypotension is common (occurring in one third of patients) and is associated with worse clinical outcomes. The LiDCO CNAP (continuous non-invasive arterial pressure) device measures haemodynamics but has not been widely adopted in ward environments. Improved early detection of hypotension by CNAP might guide interventions to improve clinical outcomes. We aimed to find the proportion of patients who tolerated LiDCO CNAP for 12 h postoperatively, to unmask episodes of hypotension detected by continuous monitoring and to characterise the haemodynamic profile at the time of hypotension. In this feasibility study, patients undergoing major elective surgery were continuously postoperatively monitored using CNAP. Haemodynamic data gathered from CNAP, including nSVRI (nominal systemic vascular resistance index), nSVI (nominal stroke volume index), SVV (stroke volume variation) and blood pressure, were analysed using Microsoft Excel and GraphPad Prism 8. 104 patients (age (mean ± sd): 68 ± 14, male (56%)) had CNAP sited postoperatively. 39% tolerated the CNAP device for at least 12 h. Within the 104 patients a mean of 81.2 min of hypotension detected by CNAP was not detected by usual care. The proportion of low/normal/high nSVI was 71%, 27% and 2%, nSVRI was 43%, 17% and 40%, respectively. CNAP monitoring was not tolerated for 12 h in the majority of patients. There were many episodes of hypotension unmasked through continuous monitoring. Based on the advanced haemodynamic data provided it is possible that the underlying cause of a third of postoperative hypotensive episodes is vasodilation rather than hypovolaemia.Trial registry number: NCT04010058 (ClinicalTrials.gov) Date of registration: 08/07/2019.

The aim of this randomized controlled trial was to determine whether applying the reverse Trendelenburg position before pneumoperitoneum has a preventive effect on increased intracranial pressure using optic nerve sheath diameter (ONSD) measurement as a noninvasive parameter. Seventy-nine patients were allocated to two groups according to whether pneumoperitoneum was applied in the supine position (group S, n = 40) or in the reverse Trendelenburg position (group RT, n = 39). The ONSD was measured at the following time points: T0: before anesthesia; T1: after endotracheal intubation; T2: after pneumoperitoneum in group S and after positioning in group RT; T3: after positioning in group S and after pneumoperitoneum in group RT; T4: 30 min after endotracheal intubation, and T5: after desufflation. The end-tidal carbon dioxide (EtCO2), regional cerebral oxygen saturation (rSO2), peripheral oxygen saturation (SpO2), mean arterial pressure (MAP), heart rate (HR), peak inspiratory pressure (Ppeak), and dynamic compliance (Cdyn) were recorded. Background and perioperative characteristics were similar in both groups. In group S, the ONSD was higher at T2, T3, T4, and T5 than that in group RT (p < 0.001, p = 0.002, p = 0.001, and p = 0.012, respectively). In the same group, the number of patients with an ONSD above 5.8 mm was higher at T2, T3, and T4 (p < 0.001, p = 0.042, p = 0.036, respectively). The rSO2 and SpO2 were not different between the groups. The mean arterial pressure was lower in group RT at T2, and the HR was not different between the groups (p < 0.001). In group S, Ppeak was higher and Cdyn was lower at T2 (p < 0.001). The number of patients with nausea was higher in group S (p = 0.027). The present study demonstrates that applying the reverse Trendelenburg position before pneumoperitoneum prevented an increase in the ONSD in patients undergoing laparoscopic cholecystectomy.Trial registration The trial was registered prior to patient enrollment at https://register.clinicaltrials.gov (NCT04224532, Date of the registration: January 8, 2020).

In the original publication of the article, the section heading "Conclusion" was placed before the sentence "The assessment of changes in cardiac output…" in page 2 instead of the sentence "From home to ICUs, innovations in…" in the last paragraph of the page 2. The correct section is given below.

Mitochondria are the primary consumers of oxygen and therefore an important location for oxygen availability and consumption measurement. A technique has been developed for mitochondrial oxygen tension (mitoPO2) measurement, incorporated in the COMET. In contrast to most textbooks, relatively high average mitoPO2 values have been reported. The first aim of this study was to verify the validity of the COMET calibration for mitoPO2 measurements in human skin. The second aim was to compare the dynamics of mitoPO2 to several other techniques assessing tissue oxygenation. Firstly, we performed a two-point calibration. Mitochondrial oxygen depletion was achieved with vascular occlusion. A high mitoPO2 was reached by local application of cyanide. MitoPO2 was compared to the arterial oxygen partial pressure (PaO2). Secondly, for deoxygenation kinetics we compared COMET variables with the LEA O2C, SenTec OxiVenT™ and Medtronic INVOS™ parameters during a vascular occlusion test. 20 healthy volunteers were recruited and resulted in 18 datasets (2 times 9 subjects). The lowest measured mitoPO2 value per subject had a median [IQR] of 3.0 [1.0-4.0] mmHg, n = 9. After cyanide application the mitoPO2 was 94.1 mmHg [87.2-110.9] and did not differ significantly (n = 9, p = 0.5) from the PaO2 of 101.0 [98.0-106.0] mmHg. In contrast to O2C, OxiVenT™ and INVOS parameters, mitoPO2 declined within seconds with pressure on the probe. The kinetics from this decline are used to mitochondrial oxygen consumption (mitoVO2). This study validates the calibration of the COMET device in humans. For mitoVO2 measurements not only blood flow cessation but application of local pressure is of great importance to clear the measurement site of oxygen-carrying erythrocytes.

We test whether a measure based on the directed transfer function (DTF) calculated from short segments of electroencephalography (EEG) time-series can be used to monitor the state of the patients also during sevoflurane anesthesia as it can for patients undergoing propofol anesthesia. We collected and analyzed 25-channel EEG from 7 patients (3 females, ages 41-56 years) undergoing surgical anesthesia with sevoflurane, and quantified the sensor space directed connectivity for every 1-s epoch using DTF. The resulting connectivity parameters were compared to corresponding parameters from our previous study (n = 8, patients anesthetized with propofol and remifentanil, but otherwise using a similar protocol). Statistical comparisons between and within studies were done using permutation statistics, a data driven algorithm based on the DTF-parameters was employed to classify the epochs as coming from awake or anesthetized state. According to results of the permutation tests, DTF-parameter topographies were significantly different between the awake and anesthesia state at the group level. However, the topographies were not significantly different when comparing results computed from sevoflurane and propofol data, neither in the awake nor in anesthetized state. Optimizing the algorithm for simultaneously having high sensitivity and specificity in classification yielded an accuracy of 95.1% (SE = 0.96%), with sensitivity of 98.4% (SE = 0.80%) and specificity of 94.8% (SE = 0.10%). These findings indicate that the DTF changes in a similar manner when humans undergo general anesthesia caused by two distinct anesthetic agents with different molecular mechanisms of action.

Monitoring intra-abdominal pressure (IAP) has become a standard in intensive care units. Correlation between the abdominal wall's thickness (AWTh) and IAP has been reported previously. The abdominal wall can be modeled as a compound of parallel dielectric slabs; changes in their width have a direct effect on the reflection coefficient of the abdominal wall at microwave frequencies. This work describes the design of a reflectometry system and its proof-of-concept trial on five patients during laparoscopic surgery. The system complies with IEEE Std. C95.1-2005 concerning exposure of humans to microwave electromagnetic fields in controlled environments. The results putatively show an inverse correlation between IAP and the reflection coefficient, and a strong dependence on the body mass index. A better understanding of the dynamics in the changes of the AWTh (during intra-abdominal hypertension) will allow further development of a microwave-based technique for the continuous non-invasive indirect monitoring of IAP in critical patients.

Recently a novel pain recognition indicator derived from electroencephalogram(EEG) signals, pain threshold index(PTI) has been developed. The aim of this study was to determine whether PTI can be used for prediction of postoperative acute pain while surgical pleth index(SPI) applied as control. Eighty patients undergoing laparoscopic urological surgery under general anesthesia were enrolled. Data of SPI, PTI and a sedative index-wavelet index(WLI) were recorded within last 10 min at the end of surgery. The postoperative pain scores (NRS, numerical rating scale) were obtained. The Bland-Altman analysis was used for evaluation of consistency between PTI and SPI, whereas receiver-operating characteristic (ROC) curves was used for the mean values of PTI, SPI, and WLI to distinguish between mild (NRS 0-3) and moderate-severe (NRS 4-10) pain, and calculate their "best-fit" cut-off values. Data from 76 patients were included for final analysis. There was a good agreement between SPI and PTI values at the end of surgery. The ROC analysis showed a cut-off PTI value of 53 to discriminate between mild and moderate-to-severe pain, while SPI is 44 for this discrimination. Further analysis indicated that PTI had a best predictive accuracy reflected by highest area under curve (AUC)(0.772, 95% CI: 0.661-0.860)with sensitivity(62.50%) and specificity(90.91%) and a best positive predictive value(83.3%,95% CI: 68.4-98.2%). PTI obtained at the end of surgery, which have better predictive accuracy for postoperative pain than SPI, could differentiate the patients with moderate-to-severe pain from those with mild pain after they awaken from anesthesia.Clinical trial registration Chinese Clinical Trials Registry: ChiCTR1900024789.

The recovery time of the motor evoked potential (MEP) amplitude following a neuromuscular blockade (NMB) during surgery is useful for interpreting low-amplitude waveforms or selecting the baseline waveform. In this study, the MEP data of 195 orthopedic cases who received a bolus dose of rocuronium at the beginning of surgery, between June 2009 and January 2016 were used. A non-linear regression analysis was applied to MEP amplitude data of multiple patients. The time taken for 90% of the maximum-amplitude recovery was estimated from the identified time series model. The 90% amplitude recovery time was 88.6 min in the pharmacological model and 89.4 min in the logistic model. These results were included in the 95% confidence interval of the previous studies. Although MEP amplitude is relatively unstable because of anesthesia, the averaged time series model of MEP amplitude can be estimated by using a large number of data.

It is commonly accepted that systolic blood pressure (SBP) is significantly higher in the brachial/radial artery than in the aorta while mean (MBP) and diastolic (DBP) pressures remain unchanged. This may have implications for outcome studies and for non-invasive devices calibration. We performed a systematic review of invasive high-fidelity pressure studies documenting BP in the aorta and brachial/radial artery. We selected articles published prior to July 2015. Pressure amplification (Amp = peripheral minus central pressure) was calculated (weighted mean). The six studies retained (n = 294, 76.5% male, mean age 63.5 years) mainly involved patients with suspected coronary artery disease (CAD). In two studies at the aortic/brachial level (n = 64), MBP and DBP were unchanged (MPAmp = 0.1 mmHg, DPAmp = -1.3 mmHg), while SBP increased (SPAmp = 4.2 mmHg; relative amplification = 3.1%). In four studies in which MBP was not documented (n = 230), brachial DBP remained unchanged and SBP increased (SPAmp = 6.6 mmHg; 4.9%). One of these four studies also reported radial SBP and DBP, not MBP (n = 12). Few high-fidelity pressure studies were found, and they have been performed mainly in elderly male patients with suspected CAD. Counter to expectations, the mean amplification of SBP from the aorta to brachial artery was < 5%. Further studies on SPAmp phenotypes (positive, null, negative) are advocated. Non-invasive device calibration assumptions were confirmed, namely unchanged MBP and DBP from the aorta to the brachial artery. Data did not allow for firm conclusions on the amount of BP changes from the aorta to the radial artery, and from the aorta to the brachial/radial arteries in other populations.

To determine whether a beat-by-beat cardiovascular index (CARDEAN: cardiovascular depth of analgesia, Alpha-2 Ltd, Lyon, France) reduces the incidence of tachycardia in ASA I-III patients undergoing orthopaedic surgery. A total of 76 patients were prospectively randomized into (1) a control group or (2) the CARDEAN group, in which the nurse anaesthetist was blinded to CARDEAN application. In addition to conventional signs, an external observer instructed the nurse anaesthetist to administer sufentanil 0.1 µg kg-1 when the CARDEAN crossed a threshold (≥ 60). The primary outcome was the incidence of tachycardia (> 120% of reference heart rate, HR). Non-invasive blood pressure (BP), electrocardiogram (ECG), O2 saturation-photoplethysmography and the bispectral index (40 < BIS < 60) were monitored. HR and an estimation of beat-by-beat BP changes acquired from photoplethysmography and ECG were combined in an algorithm that detected hypertension followed by tachycardia (index scaled 0-100). Sufentanil 0.1 µg kg-1 was administered when tachycardia, hypertension or movement ("conventional signs") was observed. Data for 66 patients (27 with known hypertension) were analysed. In the CARDEAN group, (a) the dose of sufentanil was higher (control: 0.46 µg kg-1 100 min-1, CARDEAN: 0.57 µg kg-1 100 min-1, p = 0.016), (b) the incidence rates of tachycardia and untoward events were lower (respectively: - 44%; control: 2.52 events 100 min-1 [1.98-3.22]; CARDEAN: 1.42 [1.03-1.96], p = 0.005, hazard ratio: 0.56; movement, muscular contraction, or coughing: control: 0.74 events 100 min-1 [0.47-1.16]; CARDEAN: 0.31 [0.15-0.62], p = 0.038), and (c) extubation occurred more often in the operating room (control: 76.5%, CARDEAN: 97%, p = 0.016). CARDEAN-titrated opioid administration was associated with a higher dose of sufentanil, a reduction in tachycardia and earlier emergence in ASA I-III patients undergoing major orthopaedic surgery.

The COVID-19 pandemic has resulted in an increased need for ventilators. The potential to ventilate more than one patient with a single ventilator, a so-called split ventilator setup, provides an emergency solution. Our hypothesis is that ventilation can be individualized by adding a flow restrictor to limit tidal volumes, add PEEP, titrate FiO2 and monitor ventilation. This way we could enhance optimization of patient safety and clinical applicability. We performed bench testing to test our hypothesis and identify limitations. We performed a bench testing in two test lungs: (1) determine lung compliance (2) determine volume, plateau pressure and PEEP, (3) illustrate individualization of airway pressures and tidal volume with a flow restrictor, (4a) illustrate that PEEP can be applied and individualized (4b) create and measure intrinsic PEEP (4c and d) determine PEEP as a function of flow restriction, (5) individualization of FiO2. The lung compliance varied between 13 and 27 mL/cmH2O. Set ventilator settings could be applied and measured. Extrinsic PEEP can be applied except for settings with a large expiratory time. Volume and pressure regulation is possible between 70 and 39% flow restrictor valve closure. Flow restriction in the tested circuit had no effect on the other circuit or on intrinsic PEEP. FiO2 could be modulated individually between 0.21 and 0.8 by gradually adjusting the additional flow, and minimal affecting FiO2 in the other circuit. Tidal volumes, PEEP and FiO2 can be individualized and monitored in a bench testing of a split ventilator. In vivo research is needed to further explore the clinical limitations and outcomes, making implementation possible as a last resort ventilation strategy.

General anesthesia is a reversible drug-induced state of altered arousal characterized by loss of responsiveness due to brainstem inactivation. Precise identification of the moment in which responsiveness is lost during the induction of general anesthesia is extremely important to provide information regarding an individual's anesthetic requirements and help intraoperative drug titration. To characterize the transition from responsiveness to unresponsiveness more objectively, we studied neurophysiologic-derived parameters of electromyographic records of electrically evoked blink reflex as a means of identifying the precise moment of loss of responsiveness. Twenty-five patients received a slow infusion of propofol until loss of corneal reflex while successive blink reflexes were elicited and recorded every 6 s. The level of anesthesia was assessed using an adapted version of the Richmond Agitation-Sedation Scale. Different variables of the blink reflex components were calculated and compared to the adapted version of the Richmond Agitation-Sedation score and the estimated effect-site propofol concentration. Baselines of the blink reflex responses were similar to those in literature. After propofol infusion started, the most susceptible component of the blink reflex to propofol was R2 (EC50 = 1.358 (95% CI 1.321, 1.396) µg/mL) and the most resistant was R1 (EC50 = 3.025 (95% CI 2.960, 3.090) µg/mL). Most of the patients (24 out of 25) lost the R1 component when they were still responsive to shaking and shouting and corneal reflex could be elicited clinically (time = 102.48 ± 33.00 s). Habituation was present in R2 but not in R1. The R1 component of the blink reflex was found to have a strong correlation with the adapted version of the Richmond Agitation-Sedation Scale, with amplitude correlating better than areas (ρ = - 0.721 (0.123) versus ρ = - 0.688 (0.165)). We found a strong correlation between the R1 component with the estimated propofol effect-site concentration, with amplitude correlating better than areas (ρ = - 0.838 (0.113) versus ρ = - 0.823 (0.153)) and between the clinical scale and the propofol concentration (ρ = 0.856 (0.060)). The area and amplitude of the R1 component showed to be indicators of predicting different levels of anesthesia (Pk = 0.672 (0.183) versus Pk = 0.709 (0.134)) and these are connected to the propofol concentrations (Pk = 0.593 (0.10)). Our results suggest that electrically evoked blink reflex could be used during the induction of anesthesia as a surrogate of the Richmond Agitation-Sedation Scale to provide an objective endpoint as far as a - 4. At this point, at the moment of loss of R1, the propofol infusion may be stopped, as overshooting increases slightly the effect-site concentration afterward and eventually reaching loss of responsiveness. If the desired target is not achieved, the infusion can then be resumed.

To develop and validate a mathematical model for predicting intracranial pressure (ICP) noninvasively using phase-contrast cine MRI (PC-MRI). We performed a retrospective analysis of PC-MRI from patients with communicating hydrocephalus (n = 138). The patients were recruited from Shenzhen Second People's Hospital between November 2017 and April 2020, and randomly allocated into training (n = 97) and independent validation (n = 41) groups. All participants underwent lumbar puncture and PC-MRI in order to evaluate ICP and cerebrospinal fluid (CSF) parameters (i.e., aqueduct diameter and flow velocity), respectively. A novel ICP-predicting model was then developed based on the nonlinear relationships between the CSF parameters, using the Levenberg-Marquardt and general global optimisation methods. There was no significant difference in baseline demographic characteristics between the training and independent validation groups. The accuracy of the model for predicting ICP was 0.899 in the training cohort (n = 97) and 0.861 in the independent validation cohort (n = 41). We obtained an ICP-predicting model that showed excellent performance in the noninvasive diagnosis of clinically significant communicating hydrocephalus.

Intraoperative neurophysiological monitoring (IONM) is widely used in spinal cord tumors (SCTs) removal surgery. This study mainly hypothesized that patients with prolonged latency of preoperative somatosensory evoked potentials (preSEPLat) would have more deteriorated intraoperative evoked potentials. Among 506 patients who underwent SCTs removal surgery, 74 underwent both preSEPs and IONM. The correlation between preSEPLat and intraoperative SEPs (ioSEPs) was mainly analyzed, and subgroup analysis according to anatomical type was also conducted. Secondly, whether preSEPLat related to intraoperative motor evoked potentials (ioMEPs) or postoperative motor deterioration (PMD) was analyzed. In addition, risk factors for PMD were examined among anatomical factors, including operation level, tumor-occupying area ratio, and anatomical type, as well as electrophysiological factors, such as preSEPLat, ioSEPs, and ioMEPs. Changes in ioSEP and ioMEP were considered significant even if they were recovered before the end of the monitoring. Patients with prolonged preSEPLat were more likely to have significant ioSEP changes for intradural-extramedullary (IDEM) but not for intramedullary or extradural tumors. The anatomical type and tumor-occupying area ratio were prognostic factors for transient PMD, while the ioSEPs were the only prognostic factor for persisted PMD over 4 weeks after surgery. PreSEPs are helpful in predicting the significant changes in ioSEPs during IDEM tumor removal surgery. The tumor-occupying area ratio and anatomical type are contributing factors for the transient PMD, whereas ioSEPs are prognostic factors in predicting the PMD that persists over 4 weeks after SCTs removal surgery. To our knowledge, this is the first study that mainly focused on the correlations of preoperative and intraoperative evoked potentials.

In patients at high risk of respiratory complications, pulse oximetry may not adequately detect hypoventilation events. Previous studies have proposed using thermography, which relies on infrared imaging, to measure respiratory rate (RR). These systems lack support from real-world feasibility testing for widespread acceptance. This study enrolled 101 spontaneously ventilating patients in a post-anesthesia recovery unit. Patients were placed in a 45° reclined position while undergoing pulse oximetry and bioimpedance-based RR monitoring. A thermography camera was placed approximately 1 m from the patient and pointed at the patient's face, recording continuously at 30 frames per second for 2 min. Simultaneously, RR was manually recorded. Offline imaging analysis identified the nares as a region of interest and then quantified nasal temperature changes frame by frame to estimate RR. The manually calculated RR was compared with both bioimpedance and thermographic estimates. The Pearson correlation coefficient between direct measurement and bioimpedance was 0.69 (R2 = 0.48), and that between direct measurement and thermography was 0.95 (R2 = 0.90). Limits of agreement analysis revealed a bias of 1.3 and limits of agreement of 10.8 (95% confidence interval 9.07 to 12.5) and - 8.13 (- 6.41 to - 9.84) between direct measurements and bioimpedance, and a bias of -0.139 and limits of agreement of 2.65 (2.14 to 3.15) and - 2.92 (- 2.41 to 3.42) between direct measurements and thermography. Thermography allowed tracking of the manually measured RR in the post-anesthesia recovery unit without requiring patient contact. Additional work is required for image acquisition automation and nostril identification.

The transcutaneous oxygen challenge test (OCT) is associated with central venous oxygen saturation and cardiac output index, and has predictive value for prognosis. Whether the change of transcutaneous oxygen pressure (PtcO2)-related variables can reflect lactate clearance in sepsis patients is worth studying. We conducted a prospective observational study of 79 patients with sepsis or septic shock in the ICU. Immediately after enrollment, PtcO2 monitoring was continuously performed for 6 h. The OCT was performed at enrollment (T0) and the sixth hour (T6). The correlation between lactate clearance and PtcO2-related variables such as PtcO2 at T6, ΔPtcO2 (PtcO2 at T6 - PtcO2 at T0), ΔPtcO2 index (PtcO2/PaO2 at T6 - PtcO2/PaO2 at T0), 10 OCT [(PtcO2 after 10 min on FiO2 of 1.0) - (PtcO2 at baseline)], Δ10 OCT (10 OCT at T6 - 10 OCT at T0) was analyzed. The difference of PtcO2-related variables was compared between the high and low lactate clearance groups. PtcO2 at T6 (r = 0.477, p < 0.001), ΔPtcO2 (r = 0.592, p < 0.001), ΔPtcO2 index (r = 0.553, p < 0.001) and Δ10 OCT (r = 0.379, p = 0.001) were significantly correlated with the lactate clearance. To discriminate low lactate clearance, the area under the ROC curve was largest for ΔPtcO2, which was 0.804. PtcO2 at T6, PtcO2 index, ΔPtcO2, ΔPtcO2 index and Δ10 OCT were significantly different between the two different lactate clearance groups. Low lactate clearance in the initial 6 h of resuscitation of septic shock was associated to lower improvements in PtcO2-related variables.

Measurement of pupillary characteristics, such as pupillary unrest in ambient light, and reflex dilation have been shown to be useful in a variety of clinical situations. Dedicated pupillometers typically capture images in the near-infrared to allow imaging in both light and darkness. However, because a subset of pupillary measurements can be acquired with levels of visible light suitable for conventional cameras, it is theoretically possible to capture data using general purpose cameras and computing devices such as those found on smartphones. Here we describe the development of a smartphone-based pupillometer and compare its performance with a commercial pupillometer. Smartphone pupillometry software was developed and then compared with a commercial pupillometer by performing simultaneous scans in both eyes, using the smartphone pupillometer and a commercial pupillometer. The raw scans were compared, as well as a selected pupillary index: pupillary unrest in ambient light. In 77% of the scans the software was able to successfully identify the pupil and iris. The raw data as well as calculated values of pupillary unrest in ambient light were in clinically acceptable levels of agreement; Bland-Altman analysis of raw pupil measurements yielded a 95% confidence interval of 0.26 mm. In certain situations a smartphone pupillometer may be an appropriate alternative to a commercial pupillometer.

Monitoring cerebral perfusion is important for goal-directed anesthesia. Taking advantage of the supply of the supraorbital region and Glabella from the internal carotid artery (ICA), we evaluated changes in cutaneous blood flow using laser speckle contrast imagining (LSCI) as a potential method for indirect real-time monitoring of cerebral perfusion. Nine patients (8 men, mean age 70 years) underwent eversion carotid endarterectomy under local anesthesia. Cutaneous blood flow of the forehead was monitored using LSCI. During clamping of the common carotid artery (CCA), ipsilateral supraorbital region and Glabellas cutaneous blood flow dropped from 334 ± 135 to 221 ± 109 AU (p = 0.023) (AU: arbitrary flux units) and from 384 ± 151 to 276 ± 107 AU (p = 0.023), respectively, whilst the contralateral supraorbital region cutaneous blood flow remained unchanged. The supraorbital cutaneous blood flow did not change significantly following reperfusion of the external carotid artery (ECA) (221 ± 109 to 281 ± 154 AU; p = 0.175) and ICA (281 ± 154 to 310 ± 184 AU; p = 01). A comparable trend for Glabella followed ECA (276 ± 107 to 342 ± 170 AU; p = 0.404) and ICA (342 ± 170 to 352 ± 191 AU; p = 01) reperfusion. In patients undergoing carotid endarterectomy under local anesthesia, LSCI of the supraorbital and Glabella regions reflected clamping of the CCA but did not distinguish reperfusion of the ICA from that of the ECA.

Perioperative goal-directed therapy is considered to improve patient outcomes after high-risk surgery. The association of compliance with perioperative goal-directed therapy protocols and postoperative outcomes is unclear. The purpose of this study is to determine the effect of protocol compliance on postoperative outcomes following high-risk surgery, after implementation of a perioperative goal-directed therapy protocol. Through a before-after study design, patients undergoing elective high-risk surgery before (before-group) and after implementation of a perioperative goal-directed therapy protocol (after-group) were included. Perioperative goal-directed therapy in the after-group consisted of optimized stroke volume variation or stroke volume index and optimized cardiac index. Additionally, the association of protocol compliance with postoperative complications when using perioperative goal-directed therapy was assessed. High protocol compliance was defined as ≥ 85% of the procedure time spent within the individual targets. The difference in complications during the first 30 postoperative days before and after implementation of the protocol was assessed. In the before-group, 214 patients were included and 193 patients in the after-group. The number of complications was higher in the before-group compared to the after-group (n = 414 vs. 282; p = 0.031). In the after-group, patients with high protocol compliance for stroke volume variation or stroke volume index had less complications compared to patients with low protocol compliance for stroke volume variation or stroke volume index (n = 187 vs. 90; p = 0.01). Protocol compliance by the attending clinicians is essential and should be monitored to facilitate an improvement in postoperative outcomes desired by the implementation of perioperative goal-directed therapy protocols.

Microvascular function may be modulated by various anesthetics. Desflurane and propofol anesthesia have different effects on microvascular function. However, there are few reports on the effects of sevoflurane and desflurane on microvascular function during cardiac surgery. We compared the effects of sevoflurane and desflurane on microvascular reactivity, as measured by the vascular occlusion tests (VOTs) during off-pump coronary artery bypass (OPCAB) surgery. Patients undergoing OPCAB were eligible for study inclusion. Patients were excluded if they were unsuitable for treatment with volatile agents or the VOT, had renal failure or uncontrolled diabetes, or were pregnant. The enrolled patients were randomized to receive sevoflurane or desflurane during surgery. Tissue oxygen saturation (StO2) dynamics during the VOT were measured at baseline (pre-anesthesia), pre-anastomosis, post-anastomosis of vessel grafts, and at the end of surgery. Macrohemodynamic variables, arterial blood gas parameters, and in-hospital adverse events were also evaluated. A total of 64 patients (32 in each group) were analyzed. StO2 dynamics did not differ between the groups. Compared to baseline, StO2 and the rate of recovery following vascular occlusion decreased at the end of surgery in both groups (adjusted p-value, < 0.001), and no group difference was observed. Macrohemodynamic variables, blood gas analysis results, and the rate of postoperative in-hospital adverse events were similar between the groups. Microvascular reactivity, as measured by the VOT during OPCAB, showed no difference between the sevoflurane and desflurane groups. Also, there were no group differences in macrohemodynamics or the rate of postoperative adverse events. TRIAL REGISTRATION : Clinicaltrials.gov, identifier NCT03209193; registered on July 3, 2017.

Predictions of mortality may help in the selection of patients who benefit from intensive care. Endothelial dysfunction is partially responsible for many of the organic dysfunctions in critical illness. Reactive hyperaemia is a vascular response of the endothelium that can be measured by peripheral arterial tonometry (RH-PAT). We aimed to assess if reactive hyperaemia is affected by critical illness and if it correlates with outcomes. Prospective study with a cohort of consecutive patients admitted to an Intensive Care Unit. RH-PAT was accessed on admission and on the 7th day after admission. Early and late survivors were compared to non-survivors. The effect of RH-PAT variation on late mortality was studied by a logistic regression model. The association between RH-PAT and severity scores and biomarkers of organic dysfunction was investigated by multivariate analysis. 86 patients were enrolled. Mean ln(RHI) on admission was 0.580 and was significantly lower in patients with higher severity scores (p < 0.01) and early non-survivors (0.388; p = 0.027). The model for prediction of early-mortality estimated that each 0.1 decrease in ln(RHI) increased the odds for mortality by 13%. In 39 patients, a 2nd RH-PAT measurement was performed on the 7th day. The variation of ln(RHI) was significantly different between non-survivors and survivors (- 24.2% vs. 63.9%, p = 0.026). Ln(RHI) was significantly lower in patients with renal and cardiovascular dysfunction (p < 0.01). RH-PAT is correlated with disease severity and seems to be an independent marker of early mortality, cardiovascular and renal dysfunctions. RH-PAT variation predicts late mortality. There appears to be an RH-PAT impairment in the acute phase of severe diseases that may be reversible and associated with better outcomes.

In this study, we evaluated the accuracy of oscillometric noninvasive blood pressure (NIBP) measured at the ankle in detecting low arm NIBP during cesarean delivery under spinal anesthesia. In this prospective observational study, a cohort of full-term mothers undergoing elective cesarean delivery under spinal anesthesia was examined. Simultaneous NIBP measurements were obtained from the arm and the ankle. The primary outcome was the accuracy of the ankle NIBP in detecting arm systolic blood pressure (SBP) < 90 mmHg. Other outcomes included the accuracy of ankle NIBP in detecting SBP < 80% of the baseline value. The area under the receiver operating characteristic curve (AUC) was calculated to evaluate the accuracy of ankle NIBP in detecting low arm NIBP. The Bland-Altman analysis was conducted to evaluate the agreement between values. We analyzed 1729 pairs of readings obtained from 97 mothers. Ankle SBP showed good accuracy in detecting SBP < 90 mmHg, with an AUC (95% confidence interval [CI]) of 0.90 (0.89-0.91) and a negative predictive value (NPV) of 99 (98-99%) at a cutoff value of ≤ 103 mmHg. Furthermore, ankle SBP showed good accuracy in detecting SBP < 80% of the baseline value, with an AUC (95% CI) of 0.84 (0.82-0.89) and an NPV of 95 (93-96%) at a cutoff value of ≤ 76% of the ankle baseline SBP. The mean bias between the two sites of measurement was - 5.4 ± 15.5, - 2.0 ± 11, and 0.5 ± 12.1 mmHg for SBP, diastolic blood pressure, and mean arterial pressure, respectively. In conclusion, ankle NIBP measurement is not interchangeable with arm NIBP measurement. However, ankle NIBP measurement showed good accuracy for ruling out low arm NIBP during a cesarean delivery.Clinical trial rejistration: NCT04199156.

Inter-individual variability possesses a major challenge in the regulation of hypnosis in anesthesia. Understanding the variability towards anesthesia effect is expected to assist the design of controller for anesthesia regulation. However, such studies are still very scarce in the literature. This study aims to analyze the inter-individual variability in propofol pharmacokinetics/pharmacodynamics (PK/PD) model and proposed a suitable controller to tackle the variability. This study employed Sobol' sensitivity analysis to identify significance parameters in propofol PK/PD model that affects the model output Bispectral Index (BIS). Parameters' range is obtained from reported clinical data. Based on the finding, a multi-model generalized predictive controller was proposed to regulate propofol in tackling patient variability. [Formula: see text] (concentration that produces 50% of the maximum effect) was found to have a highly-determining role on the uncertainty of BIS. In addition, the Hill coefficient, [Formula: see text], was found to be significant when there is a drastic input, especially during the induction phase. Both of these parameters only affect the process gain upon model linearization. Therefore, a predictive controller based on switching of model with different process gain is proposed. Simulation result shows that it is able to give a satisfactory performance across a wide population. Both the parameters [Formula: see text] and [Formula: see text], which are unknown before anesthesia procedure, were found to be highly significant in contributing the uncertainty of BIS. Their range of variability must be considered during the design and evaluation of controller. A linear controller may be sufficient to tackle most of the variability since both [Formula: see text] and [Formula: see text] would be translated into process gain upon linearization.

During one-lung ventilation (OLV), titrating the positive end-expiratory pressure (PEEP) to target a low driving pressure (∆P) could reduce postoperative pulmonary complications. However, it is unclear how to conduct PEEP titration: by stepwise increase starting from zero PEEP (PEEPINCREMENTAL) or by stepwise decrease after a lung recruiting manoeuvre (PEEPDECREMENTAL). In this randomized trial, we compared the physiological effects of these two PEEP titration strategies on respiratory mechanics, ventilation/perfusion mismatch and gas exchange. Patients undergoing video-assisted thoracoscopic surgery in OLV were randomly assigned to a PEEPINCREMENTAL or PEEPDECREMENTAL strategy to match the lowest ∆P. In the PEEPINCREMENTAL group, PEEP was stepwise titrated from ZEEP up to 16 cm H2O, whereas in the PEEPDECREMENTAL group PEEP was decrementally titrated, starting from 16 cm H2O, immediately after a lung recruiting manoeuvre. Respiratory mechanics, ventilation/perfusion mismatch and blood gas analyses were recorded at baseline, after PEEP titration and at the end of surgery. Sixty patients were included in the study. After PEEP titration, shunt decreased similarly in both groups, from 50 [39-55]% to 35 [28-42]% in the PEEPINCREMENTAL and from 45 [37-58]% to 33 [25-45]% in the PEEPDECREMENTAL group (both p < 0.001 vs baseline). The resulting ∆P, however, was lower in the PEEPDECREMENTAL than in the PEEPINCREMENTAL group (8 [7-11] vs 10 [9-11] cm H2O; p = 0.03). In the PEEPDECREMENTAL group the PaO2/ FIO2 ratio increased significantly after intervention (from 140 [99-176] to 186 [152-243], p < 0.001). Both the PEEPINCREMENTAL and the PEEPDECREMENTAL strategies were able to decrease intraoperative shunt, but only PEEPDECREMENTAL improved oxygenation and lowered intraoperative ΔP.Clinical trial number NCT03635281; August 2018; "retrospectively registered".

Estimating intraoperative blood loss is one of the daily challenges for clinicians. Despite the knowledge of the inaccuracy of visual estimation by anaesthetists and surgeons, this is still the mainstay to estimate surgical blood loss. This review aims at highlighting the strengths and weaknesses of currently used measurement methods. A systematic review of studies on estimation of blood loss was carried out. Studies were included investigating the accuracy of techniques for quantifying blood loss in vivo and in vitro. We excluded nonhuman trials and studies using only monitoring parameters to estimate blood loss. A meta-analysis was performed to evaluate systematic measurement errors of the different methods. Only studies that were compared with a validated reference e.g. Haemoglobin extraction assay were included. 90 studies met the inclusion criteria for systematic review and were analyzed. Six studies were included in the meta-analysis, as only these were conducted with a validated reference. The mixed effect meta-analysis showed the highest correlation to the reference for colorimetric methods (0.93 95% CI 0.91-0.96), followed by gravimetric (0.77 95% CI 0.61-0.93) and finally visual methods (0.61 95% CI 0.40-0.82). The bias for estimated blood loss (ml) was lowest for colorimetric methods (57.59 95% CI 23.88-91.3) compared to the reference, followed by gravimetric (326.36 95% CI 201.65-450.86) and visual methods (456.51 95% CI 395.19-517.83). Of the many studies included, only a few were compared with a validated reference. The majority of the studies chose known imprecise procedures as the method of comparison. Colorimetric methods offer the highest degree of accuracy in blood loss estimation. Systems that use colorimetric techniques have a significant advantage in the real-time assessment of blood loss.

Electroencephalographic (EEG) patient monitoring during general anesthesia can help to assess the real-time neurophysiology of unconscious states. Some monitoring systems like the SEDLine Root allow export of the EEG to be used for retrospective analysis. We show that changes made to the SEDLine display during recording affected the recorded EEG. These changes can strongly impact retrospective analysis of EEG signals. Real-time changes of the feed speed in the SEDLine Root device display modifies the sampling rate of the exported EEG. We used a patient as well as a simulated EEG recording to highlight the effects of the display settings on the extracted EEG. Therefore, we changed EEG feed and amplitude resolution on the display in a systematic manner. To visualize the effects of these changes, we present raw EEG segments and the density spectral array of the recording. Changing the display's amplitude resolution affects the amplitudes. If the amplitude resolution is too fine, the exported EEG contains clipped amplitudes. If the resolution is too coarse, the EEG resolution becomes too low leading to a low-quality signal making frequency analysis impossible. The proportion of clipped or zero-line data caused by the amplitude setting was > 60% in our sedated patient. Changing the display settings results in undocumented changes in EEG amplitude, sampling rate, and signal quality. The occult nature of these changes could make the analysis of data sets difficult if not invalid. We strongly suggest researchers adequately define and keep the EEG display settings to export good quality EEG and to ensure comparability among patients.