Effect of high versus standard protein provision on functional recovery in people with critical illness (PRECISe): an investigator-initiated, double-blinded, multicentre, parallel-group, randomised controlled trial in Belgium and the Netherlands.

BACKGROUND: Increased protein provision might ameliorate muscle wasting and improve long-term outcomes in critically ill patients. The aim of the PRECISe trial was to assess whether higher enteral protein provision (ie, 2·0 g/kg per day) would improve health-related quality of life and functional outcomes in critically ill patients who were mechanically ventilated compared with standard enteral protein provision (ie, 1·3 g/kg per day). METHODS: The PRECISe trial was an investigator-initiated, double-blinded, multicentre, parallel-group, randomised controlled trial in five Dutch hospitals and five Belgian hospitals. Inclusion criteria were initiation of invasive mechanical ventilation within 24 h of intensive care unit (ICU) admission and an expected duration of invasive ventilation of 3 days or longer. Exclusion criteria were contraindications for enteral nutrition, moribund condition, BMI less than 18 kg/m2, kidney failure with a no dialysis code, or hepatic encephalopathy. Patients were randomly assigned to one of four randomisation labels, corresponding with two study groups (ie, standard or high protein; two labels per group) in a 1:1:1:1 ratio through an interactive web-response system. Randomisation was done via random permuted-block randomisation in varying block sizes of eight and 12, stratified by centre. Participants, care providers, investigators, outcome assessors, data analysts, and the independent data safety monitoring board were all blinded to group allocation. Patients received isocaloric enteral feeds that contained 1·3 kcal/mL and 0·06 g of protein/mL (ie, standard protein) or 1·3 kcal/mL and 0·10 g of protein/mL (ie, high protein). The study-nutrition intervention was limited to the time period during the patient's ICU stay in which they required enteral feeding, with a maximum of 90 days. The primary outcome was EuroQoL 5-Dimension 5-level (EQ-5D-5L) health utility score at 30 days, 90 days, and 180 days after randomisation, adjusted for baseline EQ-5D-5L health utility score. This trial was registered with ClinicalTrials.gov (NCT04633421) and is closed to new participants. FINDINGS: Between Nov 19, 2020, and April 14, 2023, 935 patients were randomly assigned. 335 (35·8%) of 935 patients were female and 600 (64·2%) were male. 465 (49·7%) of 935 were assigned to the standard protein group and 470 (50·3%) were assigned to the high protein group. 430 (92·5%) of 465 patients in the standard protein group and 419 (89·1%) of 470 patients in the high protein group were assessed for the primary outcome. The primary outcome, EQ-5D-5L health utility score during 180 days after randomisation (assessed at 30 days, 90 days, and 180 days), was lower in patients allocated to the high protein group than in those allocated to the standard protein group, with a mean difference of -0·05 (95% CI -0·10 to -0·01; p=0·031). Regarding safety outcomes, the probability of mortality during the entire follow-up was 0·38 (SE 0·02) in the standard protein group and 0·42 (0·02) in the high protein group (hazard ratio 1·14, 95% CI 0·92 to 1·40; p=0·22). There was a higher incidence of symptoms of gastrointestinal intolerance in patients in the high protein group (odds ratio 1·76, 95% CI 1·06 to 2·92; p=0·030). Incidence of other adverse events did not differ between groups. INTERPRETATION: High enteral protein provision compared with standard enteral protein provision resulted in worse health-related quality of life in critically ill patients and did not improve functional outcomes during 180 days after ICU admission. FUNDING: Netherlands Organisation for Healthcare Research and Development and Belgian Health Care Knowledge Centre.

The effect of spinal versus general anaesthesia on perioperative muscle weakness in patients having bilateral total hip arthroplasty: a single center randomized clinical trial.

BACKGROUND: Perioperative neuro-endocrine stress response may contribute to acquired muscle weakness. Regional anaesthesia has been reported to improve the outcome of patients having total hip arthroplasty. In this study, it was hypothesized that spinal anaesthesia (SA) decreases the perioperative neuro-endocrine stress response and perioperatively acquired muscle weakness (PAMW), as compared to general anaesthesia (GA). METHODS: Fifty subjects undergoing bilateral total hip arthroplasty (THA) were randomly allocated to receive a standardized SA (n = 25) or GA (n = 25). Handgrip strength was assessed preoperatively, on the first postoperative day (primary endpoint) and on day 7 and 28. Respiratory muscle strength was measured by maximal inspiratory pressure (MIP). Stress response was assessed by measuring levels of Adrenocorticotropic hormone (ACTH), cortisol and interleukin-6 (IL-6). RESULTS: Handgrip strength postoperatively (day 1) decreased by 5.4 ± 15.9% in the SA group, versus 15.2 ± 11.7% in the GA group (p = 0.02). The handgrip strength returned to baseline at day 7 and did not differ between groups at day 28. MIP increased postoperatively in patients randomized to SA by 11.7 ± 48.3%, whereas it decreased in GA by 12.2 ± 19.9% (p = 0.04). On day 7, MIP increased in both groups, but more in the SA (49.0 ± 47.8%) than in the GA group (14.2 ± 32.1%) (p = 0.006). Postoperatively, the levels of ACTH, cortisol and IL-6 increased in the GA, but not in the SA group (p < 0.004). CONCLUSION: In patients having bilateral THA, SA preserved the postoperative respiratory and peripheral muscle strength and attenuated the neuro-endocrine and inflammatory responses. TRIAL REGISTRATION: clinicaltrials.gov NCT03600454.

Effect of Lidocaine 2% Versus Bupivacaine 0.5% and 1 Versus 2 Dual Separate Injections on Onset and Duration of Ultrasound-Guided Wrist Blocks: A Blinded 2 × 2 Factorial Randomized Clinical Trial.

BACKGROUND: Local anesthetics are often selected or mixed to accomplish faster onset of anesthesia. However, with ultrasound guidance, local anesthetics are delivered with greater precision, which may shorten the onset time with all classes of local anesthetics. In this study, we compared onset time and duration of ultrasound-guided wrist blocks with a fast onset versus a longer lasting local anesthetic administered via single or dual (spatially separate) injections at the level of the midforearm. METHODS: In this randomized clinical trial, 36 subjects scheduled for carpal tunnel release were randomly assigned to receive ultrasound-guided median and ulnar nerve blocks with lidocaine 2% or bupivacaine 0.5% via single or dual injections (n = 9 in each group). Subjects fulfilled the study requirements. The main outcome variables were onset and duration of sensory blockade, which were tested separately in 2 (drug) × 2 (injection) analysis of variances (ANOVAs) with interaction terms. RESULTS: Sensory block onset time did not differ significantly between subjects given lidocaine 2% (9.2 ± 3.4 minutes) or bupivacaine 0.5% (9.5 ± 3.1 minutes) (P = .76; mean difference, -0.3 ± 1.1 minutes [95% confidence interval {CI}, -2.5 to 1.9]) or between the single- (9.6 ± 2.8 minutes) and dual- (9.1 ± 3.6 minutes) injection groups (P = .69; mean difference, -0.4 ± 1.1 minutes [95% CI, -1.8 to 2.6]). Sensory duration was longer for subjects in the bupivacaine 0.5% group (27.3 ± 11.6 hours) than for subjects in the lidocaine 2% group (8.4 ± 4.1 hours) (P < .001; 95% CI, 12.7-25.1). However, sensory duration in the single- (15.7 ± 12.5 hours) and dual- (19.4 ± 13.1 hours) injection groups did not differ significantly (P = .28; mean difference, -3.7 ± 4.3 hours [95% CI, -12.6 to 5.1]). CONCLUSIONS: No significant effect was found for onset time between lidocaine 2% and bupivacaine 0.5% used in ultrasound-guided wrist blocks. Dual injections did not shorten onset time. Since mean nerve block duration was longer with bupivacaine 0.5%, our results suggest that the selection of local anesthetic for the median and ulnar nerves at the level of the midforearm should be based on the desired duration of the block and not on its speed of onset.

Catheter Port Reversal in Citrate Continuous Veno-Venous Hemofiltration.

INTRODUCTION: Knowledge of effects of catheter port reversal (CathPR), when blood is withdrawn from the venous port and returned via the arterial port, often used in dysfunctional catheters in renal replacement therapy, is limited in the setting of citrate continuous veno-venous hemofiltration (CVVH). METHODS: In this open trial, post-filter ionized calcium (PfiCa), post-filter citrate concentration (PfCC), catheter recirculation, and solute clearance were measured before, during, and after 6 hours of CathPR, in well-functioning catheters. All other settings, including citrate settings, were left constant during the study. RESULTS: Twenty-three patients were included. Mean PfiCa before CathPR of 0.36 mmol/L (SD 0.06) decreased to 0.31 (0.04) after 2 hours (P = 0.002), 0.31 (0.04) (P = 0.002) at 4 hours, and 0.31 (0.04) at 6 hours (P = 0.001). Return to normal increased mean PfiCa to 0.34 (0.06) (P = 0.006). Mean PfCC rose from 592 mg/L (SD 164) before CathPR to 649 mg/L (190) after 2 hours (P = 0.045), to 696 mg/L (192) after 4 hours (P < 0.001), and to 657 mg/L (214) after 6 hours (P = 0.018). Return to normal decreased mean PfCC to 598 mg/L (184) (P = 0.024). Mean recirculation increased during CathPR (from 4.3% [0-8.7] before to 13.8% [9.7-22.2], P < 0.001). Urea, potassium, and creatinine clearances dropped significantly, but calcium clearance was unaffected. CONCLUSION: CathPR caused a significant decrease in PfiCA and increase in PfCC. Calcium handling differs from other solutes because of increases caused in citrate concentration and subsequent effects on calcium chelation. In citrate CVVH, CathPR in dysfunctional catheters should be limited in time, with intensive follow-up. Trial registration: ClinicalTrials.gov: NCT024600416. Registered 9 November 2015.

The validation of simplified EEG derived from the bispectral index monitor in post-cardiac arrest patients.

AIMS: We aimed to validate retrospectively the accuracy of simplified electroencephalography (EEG) monitoring derived from the bispectral index (BIS) monitor in post-cardiac arrest (CA) patients. METHODS: Successfully resuscitated CA patients were transferred to the Catherization Lab followed by percutaneous coronary intervention when indicated. On arrival at the coronary care unit, bilateral BIS monitoring was started and continued up to 72 h. Raw simplified EEG tracings were extracted from the BIS monitor at a time point coinciding with the registration of standard EEG monitoring. BIS EEG tracings were reviewed by two neurophysiologists, who were asked to indicate the presence of following patterns: diffuse slowing rhythm, burst suppression pattern, cerebral inactivity, periodic epileptiform discharges and status epilepticus (SE). Additionally, these simplified BIS EEG tracings were analysed by two inexperienced investigators, who were asked to indicate the presence of SE only. RESULTS: Thirty-two simplified BIS EEG samples were analysed. Compared to standard EEG, neurophysiologists interpreted all simplified EEG samples with a sensitivity of 86%, a specificity of 100% and an interobserver variability of 0.843. Furthermore, SE was identified with a sensitivity of 80% and a specificity of 94% by two unexperienced physicians. CONCLUSION: Using a simple classification system, raw simplified EEG derived from a BIS monitoring device is comparable to standard EEG monitoring. Moreover, investigators without EEG experience were capable to identify SE in post-CA patients. Future studies will be warranted to confirm our results and to determine the added value of using simplified BIS EEG in terms of prognostic and therapeutic implications.

Impact of in or out of office hours at admission time on outcome in out-of-hospital cardiac arrest patients.

BACKGROUND: In out-of-hospital cardiac arrest (OHCA), neurological outcome is determined by the severity of neurological injury, early percutaneous coronary intervention, and application of neuroprotective temperature management. As this is a very time-intensive and manpower-intensive protocol, we hypothesized that there would be a difference in outcome between OHCA patients admitted during and out of office hours. METHODS: We prospectively collected demographic data of OHCA patients in two hospitals. All patients included were treated at 33°C for 24 h, followed by a rewarming phase until 36.6°C. During office hours were defined as arriving between 8:00 a.m. and 5:00 p.m. on weekdays. Neurological outcome at 180 days was assessed following the Cerebral Performance Category scale. RESULTS: Forty-seven (31%) patients were admitted during office hours and 105 (69%) out of office hours (P=0.199). Patients admitted during office hours were significantly older, respectively, 66±14 and 59±15 years (P=0.014). There was no significant difference between both groups in the number of patients who underwent coronary angiography, door to angiography time, and number of affected vessels. The median time spent in the target range of PaO2, PaCO2, and lactate was also not significantly different. We found no significant difference in survival until 180 days between both groups (P=0.599), even after adjustment for age (95% confidence interval: 0.44-1.90, hazard ratio: 0.912). CONCLUSION: Survival until 180 days between OHCA patients admitted during office hours or out of office hours was not significantly different in two hospitals with a fixed protocol for neuroprotection and 24/7 streamlined access to coronary angiography.

What is the value of regional cerebral saturation in post-cardiac arrest patients? A prospective observational study.

BACKGROUND: The aim of this study was to elucidate the possible role of cerebral saturation monitoring in the post-cardiac arrest setting. METHODS: Cerebral tissue saturation (SctO2) was measured in 107 successfully resuscitated out-of-hospital cardiac arrest patients for 48 hours between 2011 and 2015. All patients were treated with targeted temperature management, 24 hours at 33 °C and rewarming at 0.3 °C per hour. A threshold analysis was performed as well as a linear mixed models analysis for continuous SctO2 data to compare the relation between SctO2 and favorable (cerebral performance category (CPC) 1-2) and unfavorable outcome (CPC 3-4-5) at 180 days post-cardiac arrest in OHCA patients. RESULTS: Of the 107 patients, 50 (47 %) had a favorable neurological outcome at 180 days post-cardiac arrest. Mean SctO2 over 48 hours was 68 % ± 4 in patients with a favorable outcome compared to 66 % ± 5 for patients with an unfavorable outcome (p = 0.035). No reliable SctO2 threshold was able to predict favorable neurological outcome. A significant different course of SctO2 was observed, represented by a logarithmic and linear course of SctO2 in patients with favorable outcome and unfavorable outcome, respectively (p < 0.001). During the rewarming phase, significant higher SctO2 values were observed in patients with a favorable neurological outcome (p = 0.046). CONCLUSIONS: This study represents the largest post-resuscitation cohort evaluated using NIRS technology, including a sizeable cohort of balloon-assisted patients. Although a significant difference was observed in the overall course of SctO2 between OHCA patients with a favorable and unfavorable outcome, the margin was too small to likely represent functional outcome differentiation based on SctO2 alone. As such, these results given such methodology as performed in this study suggest that NIRS is insufficient by itself to serve in outcome prognostication, but there may remain benefit when incorporated into a multi-neuromonitoring bedside assessment algorithm.

Is venous congestion associated with reduced cerebral oxygenation and worse neurological outcome after cardiac arrest?

BACKGROUND: Post-cardiac arrest (CA) patients are at risk of secondary ischemic damage in the case of suboptimal brain oxygenation during an ICU stay. We hypothesized that elevated central venous pressures (CVP) would impair cerebral perfusion and oxygenation (venous cerebral congestion). The aim of the present study was to investigate the relationship between CVP, cerebral tissue oxygen saturation (SctO2) as assessed with near-infrared spectroscopy (NIRS) and outcome in post-CA patients. METHODS: This was an observational study in 48 post-CA patients with continuous CVP and SctO2 monitoring during therapeutic hypothermia. RESULTS: The relationship between CVP and mean SctO2 was best described by an S-shaped, third-degree polynomial regression curve (SctO2 = -0.002 × CVP(3) + 0.08 × CVP(2) - 1.07 × CVP + 69.78 %, R (2) 0.89, n = 1,949,108 data points) with high CVP (>20 mmHg) being associated with cerebral desaturation. Multivariate linear regression revealed CVP to be a more important determinant of SctO2 than mean arterial pressure (MAP) without important interaction between both (SctO2 = 0.01 × MAP - 0.20 × CVP + 0.001 × MAP × CVP + 65.55 %). CVP and cardiac output were independent determinants of SctO2 with some interaction between both (SctO2 = 1.86 × CO - 0.09 × CVP - 0.05 × CO × CVP + 60.04 %). Logistic regression revealed that a higher percentage of time with CVP above 5 mmHg was associated with lower chance of survival with a good neurological outcome (cerebral performance category (CPC) 1-2) at 180 days (OR 0.96, 95 % CI 0.92-1.00, p = 0.04). In a multivariate model, the negative association between CVP and outcome persisted after correction for hemodynamic variables, including ejection fraction and MAP. CONCLUSIONS: Elevated CVP results in lower brain saturation and is associated with worse outcome in post-CA patients. This pilot study provides support that venous cerebral congestion as indicated by high CVP may be detrimental for post-CA patients.

Cerebral tissue oxygen saturation values in volunteers and patients in the lateral decubitus and beach chair positions: a prospective observational study.

BACKGROUND: The objective of this study was to describe changes in cerebral tissue oxygen saturation (SctO2) due to changes in body position in healthy volunteers and in patients undergoing surgery under general anesthesia in the beach chair position (BCP) and lateral decubitus position (LDP). METHODS: In this prospective observational study, SctO2 was measured in 85 awake volunteers serially positioned every 15 min, beginning with the supine position (SP) and followed by the beach chair, supine, and lateral decubitus positions. Cerebral tissue oxygen saturation was also measured supine and in either the BCP or the LDP in 195 patients (according to surgical preference) undergoing elective arthroscopic shoulder surgery. We measured the lowest stable SctO2 values in each position as well as changes in blood pressure and heart rate. RESULTS: In healthy volunteers, the median (interquartile range [IQR]) lowest stable SctO2 value in the SP was 69 [66-71] %. A change in position to the BCP caused a small but statistically significant decrease in the median [IQR] lowest SctO2 value to 67 [65-70] % (P = 0.028 compared with baseline). This decrease was associated with an increase in median [IQR] arterial pressure from 83 [78-88] mmHg in the SP to 85 [81-93] mmHg in the BCP (P < 0.001 compared with baseline). In patients undergoing surgery in the BCP, the median [IQR] lowest stable SctO2 value was 55 [51-59] %, which was significantly lower (P < 0.001) than the median [IQR] lowest SctO2 value in patients in the LDP (66 [62-69] %). More patients in the BCP group (57%) showed SctO2 values ≤ 55% and/or a decrease of ≥ 20% from baseline (57%) compared with the LDP group (5% and 6%, respectively; P < 0.001 for each comparison). CONCLUSIONS: More than 55% of patients undergoing arthroscopic shoulder surgery in the BCP experience cerebral desaturation events. In volunteers without anesthesia, no desaturation events were observed. The clinical importance of these findings needs further investigation.

Regional Cerebral Oximetry During Cardiopulmonary Resuscitation: Useful or Useless?

BACKGROUND: Approximately 375,000 people annually experience sudden cardiac arrest (CA) in Europe. Most patients who survive the initial hours and days after CA die of postanoxic brain damage. Current monitors, such as electrocardiography and end-tidal capnography, provide only indirect information about the condition of the brain during cardiopulmonary resuscitation (CPR). In contrast, cerebral near-infrared spectroscopy provides continuous, noninvasive, real-time information about brain oxygenation without the need for a pulsatile blood flow. It measures transcutaneous cerebral tissue oxygen saturation (rSO2). This information could supplement currently used monitors. Moreover, an evolution in rSO2 monitoring technology has made it easier to assess rSO2 in CA conditions. OBJECTIVE: We give an overview of the literature regarding rSO2 measurements during CPR and the current commercially available devices. We highlight the feasibility of cerebral saturation measurement during CPR, its role as a quality parameter of CPR, predictor of return of spontaneous circulation (ROSC) and neurologic outcome, and its monitoring function during transport. DISCUSSION: rSO2 is feasible in the setting of CA and has the potential to measure the quality of CPR, predict ROSC and neurologic outcome, and monitor post-CA patients during transport. CONCLUSION: The literature shows that rSO2 has the potential to serve multiple roles as a neuromonitoring tool during CPR and also to guide neuroprotective therapeutic strategies.

Cerebral tissue oxygen saturation during arthroscopic shoulder surgery in the beach chair and lateral decubitus position.

Arthroscopic shoulder surgery is a common procedure and can be performed with the patient in the lateral decubitus position (LDP) or beach chair position (BCP). Although the BCP is associated with better visualization and less bleeding, it has also been associated with hemodynamic changes and consequently cerebral hypoperfusion. Devastating events reported after surgery in the BCP were attributed to a combination of the upright position and hypotension. Besides position and blood pressure, ventilator management and type of anesthesia should be taken into account. Near infrared spectroscopy might be able to provide an early warning sign of cerebral hypoperfusion during shoulder surgery in the BCP. It was therefore recommended to continuously monitor cerebral oxygenation in patients undergoing shoulder surgery in the BCP, to potentially prevent devastating outcomes. However, more clinical research on the safe lower limits of cerebral tissue oxygen saturation is needed for this recommendation to gain broad acceptance.

Increase in cerebral oxygenation during advanced life support in out-of-hospital patients is associated with return of spontaneous circulation.

INTRODUCTION: By maintaining sufficient cerebral blood flow and oxygenation, the goal of cardiopulmonary resuscitation (CPR) is to preserve the pre-arrest neurological state. To date, cerebral monitoring abilities during CPR have been limited. Therefore, we investigated the time-course of cerebral oxygen saturation values (rSO2) during advanced life support in out-of-hospital cardiac arrest. Our primary aim was to compare rSO2 values during advanced life support from patients with return of spontaneous circulation (ROSC) to patients who did not achieve ROSC. METHODS: We performed an observational study to measure rSO2 using Equanox (Nonin, Plymouth, MI) from the start of advanced life support in the pre-hospital setting. RESULTS: rSO2 of 49 consecutive out-of-hospital cardiac arrest patients were analyzed. The total increase from initial rSO2 value until two minutes before ROSC or end of advanced life support efforts was significantly larger in the group with ROSC 16% (9 to 36) compared to the patients without ROSC 10% (4 to 15) (P = 0.02). Mean rSO2 from the start of measurement until two minutes before ROSC or until termination of advanced life support was higher in patients with ROSC than in those without, namely 39% ± 7 and 31% ± 4 (P = 0.05) respectively. CONCLUSIONS: During pre-hospital advanced life support, higher increases in rSO2 are observed in patients attaining ROSC, even before ROSC was clinically determined. Our findings suggest that rSO2 could be used in the future to guide patient tailored treatment during cardiac arrest and could therefore be a surrogate marker of the systemic oxygenation state of the patient.

Feasibility of absolute cerebral tissue oxygen saturation during cardiopulmonary resuscitation.

INTRODUCTION: Current monitoring during cardiopulmonary resuscitation (CPR) is limited to clinical observation of consciousness, breathing pattern and presence of a pulse. At the same time, the adequacy of cerebral oxygenation during CPR is critical for neurological outcome and thus survival. Cerebral oximetry, based on near-infrared spectroscopy (NIRS), provides a measure of brain oxygen saturation. Therefore, we examined the feasibility of using NIRS during CPR. METHODS: Recent technologies (FORE-SIGHT™ and EQUANOX™) enable the monitoring of absolute cerebral tissue oxygen saturation (SctO2) values without the need for pre-calibration. We tested both FORE-SIGHT™ (five patients) and EQUANOX Advance™ (nine patients) technologies in the in-hospital as well as the out-of-hospital CPR setting. In this observational study, values were not utilized in any treatment protocol or therapeutic decision. An independent t-test was used for statistical analysis. RESULTS: Our data demonstrate the feasibility of both technologies to measure cerebral oxygen saturation during CPR. With the continuous, pulseless near-infrared wave analysis of both FORE-SIGHT™ and EQUANOX™ technology, we obtained SctO2 values in the absence of spontaneous circulation. Both technologies were able to assess the efficacy of CPR efforts: improved resuscitation efforts (improved quality of chest compressions with switch of caregivers) resulted in higher SctO2 values. Until now, the ability of CPR to provide adequate tissue oxygenation was difficult to quantify or to assess clinically due to a lack of specific technology. With both technologies, any change in hemodynamics (for example, ventricular fibrillation) results in a reciprocal change in SctO2. In some patients, a sudden drop in SctO2 was the first warning sign of reoccurring ventricular fibrillation. CONCLUSIONS: Both the FORE-SIGHT™ and EQUANOX™ technology allow non-invasive monitoring of the cerebral oxygen saturation during CPR. Moreover, changes in SctO2 values might be used to monitor the efficacy of CPR efforts.

Cerebral tissue oxygen saturation during therapeutic hypothermia in post-cardiac arrest patients.

AIM OF THE STUDY: This observational study was performed to assess the cerebral tissue oxygen saturation during and after therapeutic hypothermia in comatose patients after out-of-hospital cardiac arrest. METHODS: We performed a prospective observational study on the cerebral tissue oxygen saturation (SctO(2)) in post-cardiac arrest patients treated with therapeutic hypothermia (TH) between March 2011 and April 2012. SctO(2) (measured by near-infrared spectroscopy) was non-invasively and continuously measured in 28 post-cardiac arrest patients during hypothermia and active rewarming. RESULTS: At the start of mechanically induced TH, SctO(2) was 68% (65-72) and PaCO(2) was 47.2 mmHg (36.9-51.4). SctO(2) and PaCO(2) significantly decreased to 59% (57-64; p=0.006) and 36.6 mmHg (33.9-44.7; p=0.002), respectively, within the first 3h of mechanically induced TH. Cerebral tissue oxygen saturation was significantly lower in non-survivors (n=10) compared with survivors (n=18) at 3h after induction of hypothermia (p=0.02) while the decrease in PaCO(2) was similar in both groups. During TH maintenance, SctO(2) gradually returned to baseline values (69% (63-72)) at 24h, with no differences between survivors and non-survivors (p=0.65). Carbon dioxide remained within the range of mild hypocapnia (32-38 mmHg) throughout the hypothermic period. During rewarming, SctO(2) further increased to 71% (67-78). CONCLUSIONS: Induction of TH in comatose post-CA patients changes the balance between oxygen delivery and supply. The decrease in SctO(2) was less pronounced in patients surviving to hospital discharge.