Purpose: This study aims to investigate the trend of female representation in publishing in the Acta Anaesthesiologica Belgica (AAB) from 2005 to 2021. In recent years, there has been an increased focus on gender equality and disparity. However, as far as we know, an evaluation of the Belgian literature in this regard has not been undertaken before. Methods: The study’s main objective is on determining the gender of the first author, with the gender of the second and last authorship position being secondary outcomes. Additionally, the study aimed to investigate whether other variables, such as the field in which the article was published, study type, the country of origin (of the first author), the first author’s academic degree, the number of authors, and coauthors’ gender, are related to these outcomes. Results: In total 475 manuscripts were included for data collection, of which 146 (30.7%) had a female first author, 94 (19.8%) had a female second author, and 61 (12.8%) had a female last authorship position. We demonstrated a trend towards greater gender equality in the AAB over time, with more women occupying first and second authorship positions. However, we observed a stagnation in female last authorship positions, with only a small increase of last female authorship of 1.16% reaching 7.41% in 2021. Further analysis showed that female last authorship affected first female authorship. As the number of authors increases, the representation of women (particularly for the last author) diminishes compared to their male colleagues. Lastly, the analysis of gender in relation to the number of coauthors showed that male authors are more likely to publish alone (as a single author) compared to their female colleagues. The AAB predominantly published case reports, observational studies, and narrative reviews, all of which had a higher number of male authors than female authors. The study also uncovered the absence of female first authors in the four systematic reviews published. Conclusion: From 2005 to 2021, the number of female first authors in the AAB has increased, and there has been a small but steady rise in female last authorship position. However, articles published in the AAB still exhibit a lower representation of female first authors. It is crucial to conduct further research and raise attention to gender disparity in anesthetic – and per extension in scientific - literature.

Background: Patient safety remains a critical concern in the high-stakes environment of the operating room (OR). Human factors and non-technical skills (NTS) play pivotal roles in surgical performance and in preventing errors. Various assessment tools and methodologies have been developed to evaluate NTS among OR personnel, reflecting the growing recognition of their importance. Objectives: To map and analyze NTS among OR personnel during real-life surgeries using medical video recording systems and to evaluate NTS assessment tools described in existing literature. Methods: Four databases, PubMed, Web of Science, Medline and Embase, were searched for relevant studies. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was followed. Eligibility criteria included studies focusing on video recordings providing an overview of the entire OR with a focus on NTS. Results: Twenty-four articles were included in this scoping review. A total of eight NTS were assessed, most frequently communication (79%), leadership (54%), teamwork (50%) and situational awareness (50%). Observational methods varied, ranging from one or more cameras to more sophisticated medical data recorders, such as the OR Black Box (ORBB). Additionally, a wide variety of assessment methods were used, mostly validated tools (NOTSS, SPLINTS, ANTS), but also broader systems-based frameworks (SEIPS) or self-developed tools. Conclusions: This scoping review highlights the diverse methodologies used to measure NTS in the OR using medical video recordings, indicating a need for further research to address challenges and standardize practices. Despite the proven potential benefits of video recording in the OR, legal, ethical and logistical challenges may serve as possible barriers to actual implementation.

Integrated photonic systems require fast modulators to keep up with demanding operation speeds and increasing data rates. The silicon nitride integrated photonic platform is of particular interest for applications such as datacom, light detection and ranging (LIDAR), quantum photonics, and computing owing to its low losses and CMOS compatibility. Yet, this platform inherently lacks high-speed modulators. Heterogeneous integration of lithium niobate on silicon nitride waveguides can address this drawback with its strong Pockels effect. We demonstrate the first high-speed lithium niobate modulator heterogeneously integrated on silicon nitride using micro-transfer printing. The device is 2 mm long with a half-wave voltage Vπ of 14.8 V. The insertion loss and extinction ratio are 3.3 and 39 dB, respectively. Operation beyond 50 GHz has been demonstrated with the generation of open eye diagrams up to 70 Gb/s. This proof-of-principle demonstration opens up possibilities for more scalable fabrication of these trusted and performant devices.

Background: Previous studies have shown that frontline healthcare workers (HCWs) have higher rates of pre-existing mental health problems and may be therefore at risk for worsening of mental health problems during the COVID-19 pandemic. This includes an increased prevalence for anxiety, depression, acute stress and post- traumatic stress disorders. The aim of this study was to assess the subjective and professional burden of the HCWs working in frontline departments of our hospital. Objective: The aim was primarily to identify the psychological and professional impact of the COVID-19 pandemic on HCWs working in the frontline during the first two waves. Design and setting: This was a single-centre multidisciplinary survey. Methods: A printed survey was distributed to all HCWs (N=240) working in the intensive care unit and emergency department during the first and second COVID-19 outbreak. We evaluated the subjective and professional burden using 4-point Likert scale questions. Three-group comparisons based on years of work experience were made using Kruskal-Wallis tests. Comparisons per participant between two successive waves were made using Wilcoxon signed rank tests. Results: A total number of 171 HCWs (71.3%) participated in the survey. Participants mainly feared infecting their family and friends. A majority of the participants showed a high motivation working in the COVID- zone. More than half of the participants reported that their quality of sleep was unaffected by the pandemic. Despite a higher workload, work performance and interactions with colleagues were not negatively affected by the pandemic. No significant difference was found based on years of work experience. Participants had an overall decrease in personal impact during the second wave. However, work motivation decreased (p<0.001). Participants felt better protected by the offered equipment (p=0.004), but felt less appreciated (p=0.01). Conclusions: The pandemic appeared to have affected the subjective and professional burden of our participants. However, they were not as severely impacted as HCWs in some other studies. Acquired knowledge should be utilized in developing preventive and interventional strategies to support HCWs affected by the COVID-19 pandemic and potential pandemics in the future.

Background: Minimally invasive cardiac surgery via mini-thoracotomy reduces surgical trauma compared to full sternotomy. However, thoracotomy can cause severe postoperative pain. Managing postoperative pain is challenging but critical for fast rehabilitation and avoidance of chronic pain. Our objective was to compare the efficacy of analgesia of a bolus in combination with continuous local anaesthetics using a serratus anterior plane block (SAPB) catheter versus a wound infiltration catheter (CWI) in patients after minimally invasive cardiac surgery. Design and setting: We conducted a monocentric, prospective, randomized controlled trial between January 2021 and August 2022. The study was performed at Ghent University Hospital, Belgium. Methods: Patients scheduled for minimally invasive cardiac surgery via thoracoscopy and mini-thoracotomy were randomized to receive either a SABP or a CWI catheter. Postoperatively, continuous ropivacaine 0.2% was started at 10ml/h, and a supplementary bolus of 30ml ropivacaine 0.5% was administered one hour before detubation. The catheter remained in place for at least 24 hours. The primary endpoint was opioid consumption during the first 48 hours postdetubation. Secondary endpoints were anti-emetic consumption, Numerical Analogue Score for 48 hours, length of stay in the Intensive Care Unit and hospital, and incidence of chronic pain. Qualitative data were compared using the Chi – Square test, quantitative data were analyzed with the Student’s t-test. Results: During the study period, a total of 21 patients received a SAPB catheter and 26 patients received a CWI catheter. No statistical significant differences were seen in baseline characteristics. In the first 48 hours postdetubation, morphine equivalent consumption was similar in both groups (p= 0.52), with no differences observed in the early, mid- or late postoperative phases. The total morphine equivalent dose was 21.8 mg in the SAPB and 18.6 mg in the CWI group. There were no significant differences in postoperative vomiting and nausea, length of stay in the Intensive Care Unit and in the hospital and chronic thoracic pain (23% and 33% for the SAPB and CWI group, respectively, p=0.54). Conclusion: This prospective study found no significant difference in postoperative opioid consumption between patients who received a serratus anterior plane block catheter and those who received a wound catheter with bolus and continuous ropivacaine, following minimally invasive cardiac surgery via right thoracoscopy and mini-thoracotomy.

Introduction: This randomized controlled trial evaluates the effect of continuous administration of phenylephrine versus dobutamine on paraspinal oxygenation, measured by near-infrared spectroscopy (NIRS). Paraspinal NIRS-monitoring evaluates the spinal oxygenation in an indirect, continuous and real-time manner. The influence of these drugs on the paraspinal oxygenation is unknown, but can be highly relevant during major aortic repair. Methods: This dissertation discusses a preliminary data analysis concerning the first twenty patients included. Phenylephrine or dobutamine were administered continuously during elective arterial dilation procedures of the lower limb. Adhering to a predefined protocol, drug administration was titrated to maintain normotension. The primary outcome variable is the NIRS-measured paraspinal oxygen saturation (rS psO2), this at three distinct paraspinal levels (T3T4 – T9T10 – L1L2), and additionally at the deltoid muscle (rSdO2). A linear mixed modelling approach was used for statistical analysis. This manuscript adheres to the applicable CONSORT guidelines. Results: Estimated mean relative NIRS-values (e.g. changes from baseline) were calculated at the different locations. We observed an overall positive effect on these oximetry values in the dobutamine administered group, this in contrast with an overall negative effect with phenylephrine administration. Significant differences in estimated mean relative values between the groups were observed at the lumbar level (-0.67% vs 2.97%) and at the deltoid muscle (-2.63% vs 2.01%), with significantly higher values during dobutamine administration. Conclusion: By means of a mixed modelling approach to estimate mean relative values of rSpsO2 and rSdO2, we compared the effects of the administration of phenylephrine or dobutamine. Noticeable differences between the two groups were observed and seem to favour the use of dobutamine. Besides an overall positive effect of dobutamine administration, significant differences between the two interventions were observed at the lumbar level, in favour of dobutamine administration. Limitations of this analysis are the rather complex modelling, and the lack of implementation of cardiac output variables in the model.

High frequency percussive ventilation (HFPV) is a ventilation mode that combines positive pressure ventilation with some advantages of high frequency ventilation. During HFPV, a pulsatile flow is generated with high frequency and low volumes. HFPV has been used in the intensive care unit (ICU) for several decades, in case of insufficient conventional positive pressure ventilation. However, literature on its use in intraoperative care is scarce. We hypothesize that HFPV might be a better alternative to existing ventilation modi during selected operative procedures or in patients with severely compromised pulmonary and/or cardiac function. In this paper, we explain the HFPV system, we zoom in on the physiological effects of HFPV, and we describe its potential role in the intraoperative setting. Results of existing studies show that, compared to other conventional ventilation modes, HFPV improves oxygenation and ventilation without jeopardizing hemodynamics. However, because of the low quality evidence regarding physiological effects and clinical effectiveness, and due to the complicated design and set-up of the HFPV ventilator, the use of HFPV in intraoperative care is currently very limited. We conclude that HFPV could potentially be an interesting ventilation mode for procedures requiring minimal respiratory motion or low airway pressures, however larger (comparative) study trials are required to evaluate its usability in the operating room in patients with compromised pulmonary and/or cardiac function.

Extra Corporeal Membrane Oxygenation (ECMO) can be a life-saving option in critically ill patients. The aim of this study is to generate consensus on essential ECMO skills for developing an e-learning program and fine-tuning of the existing ECMO-simulation program at Ghent University Hospital, Belgium. A "Modified Delphi questionnaire" approach will be used. This technique is a method for systematic solicitation and collection of judgments on a particular topic. A set of carefully designed sequential questionnaires interspersed with summarized information and feedback of opinions derived from earlier responses is used. Experts, being physicians from different subspecialties, nurses and perfusionists, from different parts in the world are invited to participate using the software platform RedCap (R) (Research Electronic Data Capture, Nashville, Tennessee). Topics are based on the existing theoretical program and the Extracorporeal Life Support Organization (ELSO) guidelines for didactic sessions, added with new and possible interesting content. In the first round, experts are asked to score 56 statements about knowledge skills, technical skills and attitude on a 5-point Likert-scale. Additional items, suggestions on wording or any unclarities and comments can be added. Based on the information obtained from round one, the second round Delphi questionnaire will be developed. A statement will be considered to be a key competency when the internal consistency shows a Cronbach Alpha score >80% and at least 80% of the experts agreed (rating 4/5) or strongly agreed (rating 5/5) with the statement. For statistical analysis SPSS 26.0 (Statistical Package for the Social Sciences, IBM Company, US) will be used.

Tonsillectomy is routinely performed in most hospitals, both in adult and pediatric patients. A main objective of anesthesia care for these procedures is swift and comfortable recovery, permitting rapid discharge from the Post Anesthesia Care Unit (PACU). In preventing agitation, overall experience as well as rebleeding risk and the length of stay (LOS) in the PACU stand to improve. Clonidine is known for having an anxiolytic, sedative and analgesic effect, as well as for reducing postoperative vomiting in children. At our department, anesthesia consists of propofol/sufentanil/ sevoflurane anesthesia, and paracetamol/diclofenac analgesia. Some anesthetists routinely give additional clonidine 1 mcg.kg(-1) to children for tonsillectomy, others never do. This retrospective study evaluates the effect of intravenous clonidine on agitation and recovery time following tonsillectomy in different age groups. Out of all consecutive tonsillectomy cases between 1/2016 and 11/2018, a convenience sample of 473 patients was selected and included in this retrospective analysis. Of 473 included patients, 383 did not receive clonidine perioperatively and 90 did. Agitation was defined as a Ramsay Sedation Scale score of 1. In pediatric patients (<18 years), clonidine produced a relative risk reduction of agitation of 35.7% (p=0.235). We found a reduction in LOS in both pediatric and adult patients, of 5 and 11 minutes respectively (p=0.242 and p=0.262). Clonidine seems to reduce agitation and LOS in the PACU when administered perioperatively in patients undergoing tonsillectomy. A sample size calculation shows 463 patients are required in each group to achieve power of 95%. Because of the retrospective nature of our study, with its inherent risk of confounding factors, our findings should be confirmed in prospective studies.

Cardiac surgery performed by sternotomy is associated with moderate to severe acute postoperative pain. Most common analgesic schemes for per- and postoperative pain arc based on intravenous opioids. Our goal is to compare standard opioid based regimen to a multimodal pain management to determine which therapy provides the most comfort, the fastest extubation time, the least pain and the least delirium.Methods : In this prospective randomized double-blinded trial, two groups of 25 patients, were divided in an opioid group and a multimodal group after given written informed consent. Postoperative pain was scored at 8-h, 16-h, 24-h, 32-h, 40-h and 48-h by the NRS-scale in the awake patient, or the Critical-Care Pain Observation Tool (CPOT) in the sedated patient. Delirium is measured by the Intensive Care Delirium Screening Checklist (ICDSC)-score. Time to extubation, length of stay (LOS) in ICU, LOS in hospital and rescue pain medication are all registered and compared between both groups.Result : These are preliminary results of an ongoing study where we intend to include 100 patients. Fortyfive patients were successfully enrolled. Baseline characteristics were similar between two groups. The multimodal pain scheme was administered in 21 patients, 24 patients received an opioid based scheme. After linear mixed model analysis no significant differences were seen in CPOT-score (p=0,057), NRS-score (p=0,919) or consumption in rescue pain medication. Also, for the ICDSC-score no significant difference was found (p3,595). Time to extubation, LOS at ICU or LOS at the hospital showed no significant difference between both groups.Discussion : This trial shows no significant difference in pain, delirium, intubation time, LOS on ICU or LOS in hospital between multimodal analgesia versus an opioid-based analgetic protocol in cardiac surgery by sternotomy.

Introduction Near-infrared spectroscopy (NIRS) enables continuous estimation of regional tissue oxygen saturation (rStO2). Ensuring adequate tissue oxygenation in patients undergoing general anaesthesia is of paramount importance to prevent post-procedural end-organ dysfunction. During endotracheal intubation, laryngoscopy elicits an endogenous stress response, resulting in an increased mean arterial pressure (MAP). Intraoperatively, vasopressors are routinely used to counter anaesthesia-related hypotension. Since rStO2 is MAP-dependent, we aimed to study whether changes in rStO2 differ depending on the origin of increased MAP. Methods After ethical approval and written informed consent, we randomly assigned 28 patients undergoing arterial dilation of the lower limb. Phenylephrine or ephedrine were administered according to a predefined scheme, when MAP dipped below 20% from baseline. Cerebral (rScO2) and paravertebral (rSpvO2, measured at T3, T9 and lumbar) rStO2 were measured. Differences in changes in rScO2 and rSpvO2 following MAP increase obtained by vasopressor administration or laryngoscopy, were compared. After rigorous selection of fixed effects to minimize risk of multicollinearity, a linear mixed model was used to determine predicted effects of each intervention on rStO2, with intervention, rStO2-location and their two way interaction as fixed effects. Results We observed a significant increase in rScO2 (+6.27% [CI 5.19, 7.36]) following laryngoscopy, compared to ephedrine (-0.15% [CI -0.86, +0.56]) and phenylephrine (-1.57% [CI -2.27, -0.87]). rSpvO2 showed a decrease following laryngoscopy of -2.91% [CI -3.78, -2.03], whereas no changes were noted after administration of ephedrine (-0.65% [CI -1.36, +0.06]) or phenylephrine +0.35% ([CI -0.36, +1.05]). Discussion MAP increase following tracheal intubation resulted in a significantly higher rise in rScO2 and a significant lower rSpvO2 compared to changes in rStO2 following pharmacologically induced MAP increases.

Peripheral artery disease (PAD) becomes more prevalent with advancing age and is associated with elevated risk of cardiovascular events and shortened life expectancy. We investigated the prognostic performance of cardiac and vascular biomarkers in a cohort of PAD patients.A total of 95 PAD patients were enrolled (mean age 68 years, range 47 to 86 years, 73 males). Carotid intima-media thickness (cIMT), ankle brachial index (ABI), high sensitive cardiac troponin T, and N-terminal pro-B-type Natriuretic Peptide (NT-proBNP) were measured.During a median follow-up time of 9.5 years, 44 patients died and 51 patients survived. Upon Kaplan-Meier survival analysis hs-TnT (P < .001) or NT-proBNP levels (P < .001) above the median but not cIMT above the median (P = .488) or ABI below the median (P < .436)were associated with reduced survival rate. Upon univariate cox regression and after adjustment for age, gender, prior cerebral artery disease, and diabetes mellitus only the association between hs-cTnT and mortality remained significant (HR 1.93, 95% CI 1.33–2.79, P < .001). In receiver operating curve analysis hs-cTnT (area under the curve [AUC]: 0.77, 95% CI: 0.67–0.87, P < .001) NT-proBNP (AUC: 0.74, 95% CI: 0.64–0.84, P < .001) as well as hs-cTnT, and NT-proBNP combined (AUC: 0.79, 95% CI: 0.69–0.88, P < .001) were superior to cIMT (AUC: 0.64, 95%, CI: 0.53–0.76, P = .022) and ABI (AUC: 0.57, 95% CI: 0.44–0.68, P = .313) in discriminating risk for mortality.hs-cTnT and NT-proBNP should be taken into account for prognosis of patients with PAD.

We compared the effects on microvascular reactivity of hydroxyethylstarch (Volulyte®) and gelatin (Geloplasma®) during acute haemodilution. The hypothesis was that Volulyte would provide better microvascular reactivity than Geloplasma. Forty patients undergoing elective cardiac surgery were randomly assigned to receive either Volulyte or Geloplasma as the exclusive priming solution of the cardiopulmonary bypass. To evaluate microvascular reactivity, postocclusive reactive hyperaemia was examined before and after cardiopulmonary bypass. Microvascular reactivity assessments included the rate of the occlusion and reperfusion slopes and reperfusion times. After cardiopulmonary bypass, increases in reperfusion time were significantly smaller in the Volulyte group (3 (−27 to 9 [−35 to 33]%) vs 29 (−17 to 76 [−34 to 137]%) in the Geloplasma group, p = 0.02 between groups). Rate of reperfusion increased in the Volulyte group (26 (−17 to 43 [−59 to 357])%), whereas it decreased in the Geloplasma group (−22 (−47 to 16 [−84 to 113])%), p = 0.02 between groups. The shorter reperfusion times and increased reperfusion rate suggest that Volulyte maintains better microvascular reactivity than Geloplasma.

Background and Goal of Study: Previous work has demonstrated that the effect of sodium nitroprusside (SNP) on cerebral oxygen saturation (S c O 2 ) is inconsistent. We hypothesized that this variable effect might be related to functionality of the cerebral autoregulation mechanism. The use of the near-infrared spectroscopy (NIRS)-derived cerebral oximetry index (COx) has been validated as a measure to assess cerebral autoregulation. 1 The aim of the present study was to evaluate the influence of a bolus of SNP on COx. Materials and methods: After ethical committee approval and informed con- sent, 34 patients undergoing elective cardiac surgery on cardiopulmonary bypass (CPB) were included. Bilateral frontal S c O 2 was recorded continuously with NIRS. When the patient was on CPB, 20% decrease of pressure was ac-complished with a SNP bolus, while maintaining pump flow constant. Depth of Background and Goal of Study: The intravenous anesthetic propofol is widely used for the induction and maintenance of anesthesia in various clinical scenarios. Although propofol is regarded as a relatively safe anesthetic, it might interact with endothelial cells, thereby influencing their behavior and responsiveness to external stimuli. Aim of the study was to investigate the effects of clinically relevant concentrations of propofol on cell proliferation, cell death, barrier function and wound healing capacity of human endothelial cells cultured in-vitro. The principal mechanism of cardiac toxicity of bupivacaine relates to the blockade of myocardial sodium channels, leads to an increase in the QRS duration. experimental sug- gest that lipid emulsion is effective in reversing bupivacaine cardiac toxicity. We to evaluate the temporal evolution of the QRS widening induced by bupivacaine with the Intralipid administration. Materials and methods: in order a increase in QRS duration the toxic The Electrocar- diographic parameters were recorded and blood samples were taken after bupivacaine and minutes after Intralipid administration mL/ kg by an infusion of Three served as a control group, infusion administered instead of Intralipid. Statistical analysis: Mann-Whitney test.

Results Cardiac troponin T (cTnT) is used as a specific marker for myocardial ischaemia, although its value remains ill-defined in off-pump coronary surgery (OPCAB). The present retrospective observational study aimed to determine the release patterns of cTnT after OPCAB and relate these to electrocardiographic changes. • After ethical committee approval and informed consent, data from 131 OPCAB patients were retrieved from a database of which 57 patients were excluded for further analysis because of missing data • cTnT samples were measured preoperatively, at arrival at the intensive care unit (ICU), and 6, 12, 24 and 48 hours afterwards • 12-lead ECGs were recorded preoperatively, at arrival at ICU, 1, 2 and 5 days postoperatively

BACKGROUND Although both pressure and flow are considered important determinants of regional organ perfusion, the relative importance of each is less established. The aim of the present study was to evaluate the impact of variations in flow, pressure, or both on cerebral and whole-body oxygen saturation. METHODS Thirty-four consenting patients undergoing elective cardiac surgery on cardiopulmonary bypass were included. Using a randomized cross-over design, four different haemodynamic states were simulated: (i) 20% flow decrease, (ii) 20% flow decrease with phenylephrine to restore baseline pressure, (iii) 20% pressure decrease with sodium nitroprusside (SNP) under baseline flow, and (iv) increased flow with baseline pressure. The effect of these changes was evaluated on cerebral (Sc(O₂)) and systemic (Sv(O₂)) oxygen saturation, and on systemic oxygen extraction ratio (OER). Data were assessed by within- and between-group comparisons. RESULTS Decrease in flow was associated with a decrease in [from 63.5 (7.4) to 62.0 (8.5) %, P<0.001]. When arterial pressure was restored with phenylephrine during low flow, Sc(O₂) further decreased from 61.0 (9.7) to 59.2 (10.2) %, P<0.001. Increase in flow was associated with an increase in Sc(O₂) from 62.6 (7.7) to 63.6 (8.9) %, P=0.03, while decreases in pressure with the use of SNP did not affect Sc(O₂). Sv(O₂) was significantly lower (P<0.001) and OER was significantly higher (P<0.001) in the low flow arms. CONCLUSIONS In the present elective cardiac surgery population, Sc(O₂) and Sv(O₂) were significantly lower with lower flow, regardless of systemic arterial pressure. Moreover, phenylephrine administration was associated with a reduced cerebral and systemic oxygen saturation.

Background. We hypothesized that previously reported contradictory results regarding the equivalence of mixed venous (Smv(O2)) and cerebral (rS(c)O(2)) oxygen saturation might be related to time delay issues and to measurement technology. In order to explore these two factors, we designed a prospective clinical study comparing Smv(O2) with relative (INVOS (R)) and absolute (Foresight (R)) rS(c)O(2) measurements.Methods. Forty-two consenting patients undergoing elective off-pump coronary artery bypass grafting were included. Two INVOS and two Foresight sensors continuously registered rS(c)O(2). Smv(O2) was measured continuously via a pulmonary artery catheter. Data were assessed by within-and between-group comparisons and correlation analysis.Results. A similar time delay of 19 (4) and 18 (4) s was found for Smv(O2) compared with rS(c)O(2) measurements by Foresight and INVOS, respectively, during haemodynamic changes. After adjusting for this time delay, the correlation between SmvO(2) and rS(c)O(2) increased from r=0.25 to 0.75 (P<0.001) for Foresight, and from r=0.28 to 0.73 (P<0.001) for INVOS. Comparison of Foresight and INVOS revealed significant differences in absolute rS(c)O(2) values (range 58-89% for Foresight and 28-95% for INVOS). Changes in rS(c)O(2) in response to acute haemodynamic alterations were significantly more pronounced with INVOS compared with Foresight (P<0.001).Conclusions. Considering the important time delay with Smv(O2), rS(c)O(2) seems to reflect more appropriately acute haemodynamic alterations. This might suggest its use as a valid alternative to invasive monitoring of tissue oxygen saturation. Relative and absolute rS(c)O(2) measurements demonstrated significant differences in measured rS(c)O(2) values and in the magnitude of rS(c)O(2) changes during haemodynamic alterations.