Increase in regional cerebral saturation after elective electrical cardioversion of atrial fibrillation is only transient and without beneficial effects on neuropsychological functioning: cerebral saturation during electrical cardioversion.

We aimed to confirm the positive association between a successful electrical cardioversion (ECV) and increase in SctO2 and investigated whether this increase is persisting or not. Secondary, the influence of a successful ECV on the neuropsychological function and the association with SctO2 was assessed as well. SctO2 was measured continuously during elective ECV using near-infrared spectroscopy. Measurements started before induction of sedation and ended 15 min after awakening. A second measurement took place 4 to 6 weeks after ECV. To assess neuropsychological functioning, patients performed standardized neuropsychological tests before ECV and at follow-up and were compared to healthy volunteers as control group. SctO2 was measured in 60 patients during elective ECV. ECV was successful in 50 AF patients, while in ten patients sinus rhythm was not obtained. SctO2 increased immediately after successful ECV in 50 patients (1% (- 5 to 4); p = 0.031), but not after unsuccessful ECV in 10 patients (- 1% (- 5;3); p = 0.481). This SctO2 change was positively correlated with the instant change in blood pressure (R2 = 0.391; p = 0.004). At follow-up, SctO2 values were no longer increased. Nevertheless, successful ECV improved the patient's quality of life but did not influence neuropsychological functioning at follow-up. A transient, instant SctO2 increase was observed after successful ECV. This temporary increase in SctO2 did not influence the neuropsychological functioning of the patients. Though, the quality of life of patients with a successful ECV improved.

Association between postoperative delirium and postoperative cerebral oxygen desaturation in older patients after cardiac surgery.

BACKGROUND: Near-infrared spectroscopy non-invasively measures regional cerebral oxygen saturation. Intraoperative cerebral desaturations have been associated with worse neurological outcomes. We investigated whether perioperative cerebral desaturations are associated with postoperative delirium in older patients after cardiac surgery. METHODS: Patients aged 70 yr and older scheduled for on-pump cardiac surgery were included between 2015 and 2017 in a single-centre, prospective, observational study. Baseline cerebral oxygen saturation was measured 1 day before surgery. Throughout surgery and after ICU admission, cerebral oxygen saturation was monitored continuously up to 72 h after operation. The presence of delirium was assessed using the confusion assessment method for the ICU. Association with delirium was evaluated with unadjusted analyses and multivariable logistic regression. RESULTS: Ninety-six of 103 patients were included, and 29 (30%) became delirious. Intraoperative cerebral oxygen saturation was not significantly associated with postoperative delirium. The lowest postoperative cerebral oxygen saturation was lower in patients who became delirious (P=0.001). The absolute and relative postoperative cerebral oxygen saturation decreases were more marked in patients with delirium (13 [6]% and 19 [9]%, respectively) compared with patients without delirium (9 [4]% and 14 [5]%; P=0.002 and P=0.001, respectively). These differences in cerebral oxygen saturation were no longer present after excluding cerebral oxygen saturation values after patients became delirious. Older age, previous stroke, higher EuroSCORE II, lower preoperative Mini-Mental Status Examination, and more substantial absolute postoperative cerebral oxygen saturation decreases were independently associated with postoperative delirium incidence. CONCLUSIONS: Postoperative delirium in older patients undergoing cardiac surgery is associated with absolute decreases in postoperative cerebral oxygen saturation. These differences appear most detectable after the onset of delirium. CLINICAL TRIAL REGISTRATION: NCT02532530.

Early goal-directed haemodynamic optimization of cerebral oxygenation in comatose survivors after cardiac arrest: the Neuroprotect post-cardiac arrest trial.

AIMS: During the first 6-12 h of intensive care unit (ICU) stay, post-cardiac arrest (CA) patients treated with a mean arterial pressure (MAP) 65 mmHg target experience a drop of the cerebral oxygenation that may cause additional cerebral damage. Therefore, we investigated whether an early goal directed haemodynamic optimization strategy (EGDHO) (MAP 85-100 mmHg, SVO2 65-75%) is safe and could improve cerebral oxygenation, reduce anoxic brain damage, and improve outcome when compared with a MAP 65 mmHg strategy. METHODS AND RESULTS: A total of 112 out-of-hospital CA patients were randomly assigned to EGDHO or MAP 65 mmHg strategies during the first 36 h of ICU stay. The primary outcome was the extent of anoxic brain damage as quantified by the percentage of voxels below an apparent diffusion coefficient (ADC) score of 650.10-6 mm2/s on diffusion weighted magnetic resonance imaging (at day 5 ± 2 post-CA). Main secondary outcome was favourable neurological outcome (CPC score 1-2) at 180 days. In patients assigned to EGDHO, MAP (P < 0.001), and cerebral oxygenation during the first 12 h of ICU stay (P = 0.04) were higher. However, the percentage of voxels below an ADC score of 650.10-6 mm2/s did not differ between both groups [16% vs. 12%, odds ratio 1.37, 95% confidence interval (CI) 0.95-0.98; P = 0.09]. Also, the number of patients with favourable neurological outcome at 180 days was similar (40% vs. 38%, odds ratio 0.98, 95% CI 0.41-2.33; P = 0.96). The number of serious adverse events was lower in patients assigned to EGDHO (P = 0.02). CONCLUSION: Targeting a higher MAP in post-CA patients was safe and improved cerebral oxygenation but did not improve the extent of anoxic brain damage or neurological outcome.

The Prognostic Value of Simplified EEG in Out-of-Hospital Cardiac Arrest Patients.

BACKGROUND: We previously validated simplified electroencephalogram (EEG) tracings obtained by a bispectral index (BIS) device against standard EEG. This retrospective study now investigated whether BIS EEG tracings can predict neurological outcome after cardiac arrest (CA). METHODS: Bilateral BIS monitoring (BIS VISTA™, Aspect Medical Systems, Inc. Norwood, USA) was started following intensive care unit admission. Six, 12, 18, 24, 36 and 48 h after targeted temperature management (TTM) at 33 °C was started, BIS EEG tracings were extracted and reviewed by two neurophysiologists for the presence of slow diffuse rhythm, burst suppression, cerebral inactivity and epileptic activity (defined as continuous, monomorphic, > 2 Hz generalized sharp activity or continuous, monomorphic, < 2 Hz generalized blunt activity). At 180 days post-CA, neurological outcome was determined using cerebral performance category (CPC) classification (CPC1-2: good and CPC3-5: poor neurological outcome). RESULTS: Sixty-three out-of-hospital cardiac arrest patients were enrolled for data analysis of whom 32 had a good and 31 a poor neurological outcome. Epileptic activity within 6-12 h predicted CPC3-5 with a positive predictive value (PPV) of 100%. Epileptic activity within time frames 18-24 and 36-48 h showed a PPV for CPC3-5 of 90 and 93%, respectively. Cerebral inactivity within 6-12 h predicted CPC3-5 with a PPV of 57%. In contrast, cerebral inactivity between 36 and 48 h predicted CPC3-5 with a PPV of 100%. The pattern with the worst predictive power at any time point was burst suppression with PPV of 44, 57 and 40% at 6-12 h, at 18-24 h and at 36-48 h, respectively. Slow diffuse rhythms at 6-12 h, at 18-24 h and at 36-48 h predicted CPC1-2 with PPV of 74, 76 and 80%, respectively. CONCLUSION: Based on simplified BIS EEG, the presence of epileptic activity at any time and cerebral inactivity after the end of TTM may assist poor outcome prognostication in successfully resuscitated CA patients. A slow diffuse rhythm at any time after CA was indicative for a good neurological outcome.

Mean arterial pressure of 65 mm Hg versus 85-100 mm Hg in comatose survivors after cardiac arrest: Rationale and study design of the Neuroprotect post-cardiac arrest trial.

BACKGROUND: Post-cardiac arrest (CA) patients admitted to the intensive care unit (ICU) have a poor prognosis, with estimated survival rates of around 30%-50%. On admission, these patients have a large cerebral penumbra at risk for additional damage in case of suboptimal brain oxygenation during their stay in the ICU. The aim of the Neuroprotect post-CA trial is to investigate whether forcing mean arterial blood pressure (MAP) and mixed venous oxygen saturation (SVO2) in a specific range (MAP 85-100 mm Hg, SVO2 65%-75%) with additional pharmacological support (goal-directed hemodynamic optimization) may better salvage the penumbra, reduce cerebral ischemia, and improve functional outcome when compared with current standard of care (MAP 65 mm Hg). DESIGN: The Neuroprotect post-CA trial (NCT02541591) is a multicenter, randomized, parallel-group, open-label, assessor-blinded, monitored, and investigator-driven clinical trial. The trial will be conducted in 2 tertiary care hospitals in Belgium (UZ Leuven and ZOL-Genk). A total of 112 eligible patients will be randomly assigned in a 1:1 ratio to goal-directed hemodynamic optimization or standard care strategy by an interactive voice response system. Patients will be stratified according to the presence of an initial shockable rhythm. Adult patients (≥18 years) resuscitated from out-of-hospital CA of a presumed cardiac cause who are unconscious upon hospital admission are eligible for inclusion. Patients can be included irrespective of their presenting heart rhythm but need to have a sustained return of spontaneous circulation. Trial interventions will take 36 hours starting from ICU admission. The primary outcome is the extent of cerebral ischemia as quantified by the apparent diffusion coefficient on diffusion-weighted magnetic resonance imaging to be performed at day 4-5 post-CA. Secondary outcomes include surrogate biomarkers of brain injury (neuron specific enolase) at day 1-5, neuropsychological and functional testing at hospital discharge, a Short Form-36 health questionnaire at 180 days, and outcome as assessed with cerebral performance category scores at ICU discharge and at 180 days. CONCLUSIONS: The Neuroprotect post-CA trial will investigate whether a more aggressive hemodynamic strategy to obtain a MAP 85-100 mm Hg and SVO2 65%-75% reduces brain ischemia and improves outcome when compared with standard treatment (MAP 65 mm Hg) in comatose post-CA survivors.

Recorded time periods of bispectral index values equal to zero predict neurological outcome after out-of-hospital cardiac arrest.

BACKGROUND: Prognostication in out-of-hospital cardiac arrest (OHCA) survivors is often difficult. Recent studies have shown the predictive ability of bispectral index (BIS) monitoring to assist with early neuroprognostication. The aim of this study was to investigate whether characteristics of BIS values equal to zero (BIS 0) (i.e. duration and/or uni- versus bilateral presence) instead of simply their occurrence are better indicators for poor neurological outcome after OHCA by aiming at a specificity of 100%. METHODS: Between 2011 and 2015, all successfully resuscitated OHCA patients were treated with targeted temperature management (TTM) at 33 °C for 24 hours followed by rewarming over 12 hours (0.3 °C/h). In total, BIS values were registered in 77 OHCA patients. The occurrence of unilateral (BIS 0 at one hemisphere) and bilateral (BIS 0 at both hemispheres) BIS 0 values as well as their total duration were calculated. Receiver operating characteristic (ROC) curves were constructed using the total duration with BIS 0 values calculated from the initiation of TTM onwards to determine poor neurological outcome. RESULTS: In 30 of 77 OHCA patients (39%), at least one BIS 0 value occurred during the first 48 hours after admission. Of these 30 patients, six (20%) had a good (cerebral performance category (CPC) 1-2) and 24 (80%) a poor neurological outcome (CPC3-5) at 180 days post-CA. Within these 30 patients, the incidence of bilateral BIS 0 values was higher in patients with poor neurological outcome (CPC1-2: 2 (33%) vs. CPC3-5: 19 (79%); p = 0.028). The presence of a BIS 0 value predicted poor neurological outcome with a sensitivity of 62% and specificity of 84% (AUC: 0.729; p = 0.001). With a ROC analysis, a total duration of 30,3 minutes with BIS 0 values calculated over the first 48 hours predicted poor neurological outcome with a sensitivity of 63% and specificity of 100% (AUC: 0.861; p = 0.007). CONCLUSIONS: This study shows that a prolonged duration with (bilateral) BIS 0 values serves as a better outcome predictor after OHCA as compared to a single observation.

The Effect of Deep Versus Moderate Neuromuscular Block on Surgical Conditions and Postoperative Respiratory Function in Bariatric Laparoscopic Surgery: A Randomized, Double Blind Clinical Trial.

BACKGROUND: In recent literature, it has been suggested that deep neuromuscular block (NMB) improves surgical conditions during laparoscopy; however, the evidence supporting this statement is limited, and this was not investigated in laparoscopic bariatric surgery. Moreover, residual NMB could impair postoperative respiratory function. We tested the hypotheses that deep NMB could improve the quality of surgical conditions for laparoscopic bariatric surgery compared with moderate NMB and investigated whether deep NMB puts patients at risk for postoperative respiratory impairment compared with moderate NMB. METHODS: Sixty patients were evenly randomized over a deep NMB group (rocuronium bolus and infusion maintaining a posttetanic count of 1-2) and a moderate NMB group (rocuronium bolus and top-ups maintaining a train-of-four count of 1-2). Anesthesia was induced and maintained with propofol and remifentanil. The primary outcome measures were the quality of surgical conditions assessed by a single surgeon using a 5-point rating scale (1 = extremely poor, 5 = optimal), the number of intra-abdominal pressure increases >18 cmH2O and the duration of surgery. Secondary outcome measure was the postoperative pulmonary function assessed by peak expiratory flow, forced expiratory volume in 1 second, and forced vital capacity, and by the need for postoperative respiratory support. Data are presented as mean ± standard deviation with estimated treatment effect (ETE: mean difference [95% confidence interval]) for group comparisons. RESULTS: There was no statistically significant difference in the surgeon's rating regarding the quality of the surgical field between the deep and moderate NMB group (4.2 ± 1.0 vs 3.9 ± 1.1; P = .16, respectively; ETE: 0.4 [-0.1, 0.9]). There was no difference in the proportional rating of surgical conditions over the 5-point rating scale between both groups (P = .91). The number of intra-abdominal pressure increases >18 cmH2O and the duration of surgery were not statistically different between the deep and moderate NMB group (0.2 ± 0.9 vs 0.3 ± 1.0; P = .69; ETE: -0.1 [-0.5, 0.4] and 61.3 ± 15.1 minutes vs 70.6 ± 20.8 minutes; P = .07, ETE: -9.3 [-18.8, 0.1], respectively). All the pulmonary function tests were considerably impaired in both groups when compared with baseline (P < .001). There was no statistically significant difference in the decrease in peak expiratory flow, forced expiratory volume in 1 second, and forced vital capacity (expressed as % change from baseline) between the deep and the moderate NMB group. CONCLUSIONS: Compared with a moderate NMB, there was insufficient evidence to conclude that deep NMB improves surgical conditions during laparoscopic bariatric surgery. Postoperative pulmonary function was substantially decreased after laparoscopic bariatric surgery independently of the NMB regime that was used. The study is limited by a small sample size.

Influence of continuously evolving transcatheter aortic valve implantation technology on cerebral oxygenation.

This study assessed the influence of the evolution in Transcatheter Aortic Valve Implantation technology on cerebral oxygenation. Cerebral oxygenation was measured continuously with Near-Infrared Spectroscopy and compared retrospectively between balloon-expandable, self-expandable and differential deployment valves which were implanted in 12 (34%), 17 (49%) and 6 patients (17%), respectively. Left and right SctO2 values were averaged at four time points and used for analysis (i.e. at baseline, balloon-aortic valvuloplasty, valve deployment, and at the end of the procedure). During balloon-aortic valvuloplasty and valve deployment, cerebral oxygenation decreased in patients treated with balloon or self-expandable valves (balloon-expandable: p = 0.003 and p = 0.002; self-expandable: p < 0.001 and p = 0.003, respectively). The incidence of cerebral desaturations below 80% of baseline was significantly larger in patients treated with balloon-expandable valves (p = 0.001). In contrast, patients who received differential deployment valves never experienced a cerebral desaturation below 80% of baseline. Furthermore, both the incidence and duration below a cerebral oxygenation of 55% was significantly different between balloon and self-expandable valves (p = 0.038 and p = 0.018, respectively). This study demonstrated that Transcatheter Aortic Valve Implantation procedures are associated with significant cerebral desaturations, especially during balloon-aortic valvuloplasty and valve deployment. Moreover, our results showed that latest innovations in Transcatheter Aortic Valve Implantation technology beneficially influenced the adequacy of cerebral perfusion.

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.

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.

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.

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.

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.

Sepsis is associated with altered cerebral microcirculation and tissue hypoxia in experimental peritonitis.

OBJECTIVE: Alterations in cerebral microvascular blood flow may develop during sepsis, but the consequences of these abnormalities on tissue oxygenation and metabolism are not well defined. We studied the evolution of microvascular blood flow, brain oxygen tension (PbO2), and metabolism in a clinically relevant animal model of septic shock. DESIGN: Prospective randomized animal study. SETTING: University hospital research laboratory. SUBJECTS: Fifteen invasively monitored and mechanically ventilated female sheep. INTERVENTIONS: The sheep were randomized to fecal peritonitis (n = 10) or a sham procedure (n = 5), and craniectomies were performed to enable evaluation of cerebral microvascular blood flow, PbO2, and metabolism. The microvascular network of the left frontal cortex was evaluated (at baseline, 6, 12, and 18 hr) using sidestream dark-field videomicroscopy. Using an off-line semiquantitative method, functional capillary density and the proportion of small perfused vessels were calculated. PbO2 was measured hourly by a parenchymal Clark electrode, and cerebral metabolism was assessed by the lactate/pyruvate ratio using brain microdialysis; both these systems were placed in the right frontal cortex. MEASUREMENT AND MAIN RESULTS: In septic animals, cerebral functional capillary density (from 3.1 ± 0.5 to 1.9 ± 0.4 n/mm, p < 0.001) and proportion of small perfused vessels (from 98% ± 2% to 84% ± 7%, p = 0.004) decreased over the 18-hour study period. Concomitantly, PbO2 decreased (61 ± 5 to 41 ± 7 mm Hg, p < 0.001) and lactate/pyruvate ratio increased (23 ± 5 to 36 ± 19, p < 0.001). At 18 hours, when shock was present, animals with a mean arterial pressure less than 65 mm Hg (n = 6) had similar functional capillary density, proportion of small perfused vessels, and PbO2 values but significantly higher lactate/pyruvate ratio (46 ± 18 vs 20 ± 4, p = 0.009) compared with animals with an mean arterial pressure of 65-70 mm Hg (n = 4). CONCLUSIONS: Impaired cerebral microcirculation during sepsis is associated with progressive impairment in PbO2 and brain metabolism. Development of severe hypotension was responsible for a further increase in anaerobic metabolism. These alterations may play an important role in the pathogenesis of brain dysfunction during sepsis.

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.

The effect of higher or lower mean arterial pressure on kidney function after cardiac arrest: a post hoc analysis of the COMACARE and NEUROPROTECT trials.

BACKGROUND: We aimed to study the incidence of acute kidney injury (AKI) in out-of-hospital cardiac arrest (OHCA) patients treated according to low-normal or high-normal mean arterial pressure (MAP) targets. METHODS: A post hoc analysis of the COMACARE (NCT02698917) and Neuroprotect (NCT02541591) trials that randomized patients to lower or higher targets for the first 36 h of intensive care. Kidney function was defined using the Kidney Disease Improving Global Outcome (KDIGO) classification. We used Cox regression analysis to identify factors associated with AKI after OHCA. RESULTS: A total of 227 patients were included: 115 in the high-normal MAP group and 112 in the low-normal MAP group. Eighty-six (38%) patients developed AKI during the first five days; 40 in the high-normal MAP group and 46 in the low-normal MAP group (p = 0.51). The median creatinine and daily urine output were 85 µmol/l and 1730 mL/day in the high-normal MAP group and 87 µmol/l and 1560 mL/day in the low-normal MAP group. In a Cox regression model, independent AKI predictors were no bystander cardiopulmonary resuscitation (p < 0.01), non-shockable rhythm (p < 0.01), chronic hypertension (p = 0.03), and time to the return of spontaneous circulation (p < 0.01), whereas MAP target was not an independent predictor (p = 0.29). CONCLUSION: Any AKI occurred in four out of ten OHCA patients. We found no difference in the incidence of AKI between the patients treated with lower and those treated with higher MAP after CA. Higher age, non-shockable initial rhythm, and longer time to ROSC were associated with shorter time to AKI. CLINICAL TRIAL REGISTRATION: COMACARE (NCT02698917), NEUROPROTECT (NCT02541591).

Therapeutic hypothermia and traumatic brain injury.

PURPOSE OF REVIEW: Therapeutic hypothermia after traumatic brain injury (TBI)? For the last 10 years, no topic has been more popular and more controversial among neurointensivists. This article reviews the most current findings (experimental, clinical, adult and pediatric TBI), as well as the clinical management of therapeutic hypothermia. RECENT FINDINGS: Despite ample experimental evidence, the clinical utility of therapeutic hypothermia has still to be conclusively demonstrated in terms of reduced mortality or improved functional recovery after TBI (even in pediatric TBI). Current findings support that hypothermia should be initiated as soon as possible, for at least 48 h duration, and that outcome is worse when barbiturates are part of ICU management. Currently, available cooling techniques, including prehospital cooling protocols, expand and improve clinical management of therapeutic hypothermia. SUMMARY: Taking into consideration all results from clinical hypothermia TBI studies discussion has to be focused around the possibility that a better outcome could be achieved if protocols for therapeutic hypothermia are reviewed. It is possible that the negative effects of the cooling and the rewarming procedure currently overshadow the neuroprotective effects.