Cathy De Deyne

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.

Feasibility of absolute cerebral tissue oxygen saturation during cardiopulmonary resuscitation

IntroductionCurrent 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.MethodsRecent 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.ResultsOur 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.ConclusionsBoth 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.

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

IntroductionBy 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.MethodsWe performed an observational study to measure rSO2 using Equanox™ (Nonin, Plymouth, MI) from the start of advanced life support in the pre-hospital setting.ResultsrSO2 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.ConclusionsDuring 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.

Scalable Predictive Analysis in Critically Ill Patients Using a Visual Open Data Analysis Platform

With the accumulation of large amounts of health related data, predictive analytics could stimulate the transformation of reactive medicine towards Predictive, Preventive and Personalized (PPPM) Medicine, ultimately affecting both cost and quality of care. However, high-dimensionality and high-complexity of the data involved, prevents data-driven methods from easy translation into clinically relevant models. Additionally, the application of cutting edge predictive methods and data manipulation require substantial programming skills, limiting its direct exploitation by medical domain experts. This leaves a gap between potential and actual data usage. In this study, the authors address this problem by focusing on open, visual environments, suited to be applied by the medical community. Moreover, we review code free applications of big data technologies. As a showcase, a framework was developed for the meaningful use of data from critical care patients by integrating the MIMIC-II database in a data mining environment (RapidMiner) supporting scalable predictive analytics using visual tools (RapidMiner’s Radoop extension). Guided by the CRoss-Industry Standard Process for Data Mining (CRISP-DM), the ETL process (Extract, Transform, Load) was initiated by retrieving data from the MIMIC-II tables of interest. As use case, correlation of platelet count and ICU survival was quantitatively assessed. Using visual tools for ETL on Hadoop and predictive modeling in RapidMiner, we developed robust processes for automatic building, parameter optimization and evaluation of various predictive models, under different feature selection schemes. Because these processes can be easily adopted in other projects, this environment is attractive for scalable predictive analytics in health research.

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.

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.

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

BackgroundThe 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).MethodsIn 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.ResultsIn 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).ConclusionsMore 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.RésuméContexteL’objectif de cette étude était de décrire les changements de la saturation en oxygène cérébral tissulaire (SctO2) provoqués par les changements de position du corps chez des volontaires sains et des patients subissant une chirurgie sous anesthésie générale en position assise (PAs - beach chair position) et en décubitus latéral (DL).MéthodeDans cette étude observationnelle prospective, on a mesuré la SctO2 de 85 volontaires sains éveillés repositionnés en série toutes les 15 minutes, en commençant en position allongée (PAl) puis en position assise, puis allongée à nouveau, et finalement en décubitus latéral. La saturation en oxygène cérébral tissulaire a également été mesurée en position allongée et en PAs ou en DL chez 195 patients (selon la préférence chirurgicale) subissant une arthroscopie non urgente de l’épaule. Nous avons mesuré les valeurs stables de SctO2 les plus basses dans chaque position ainsi que les changements de tension artérielle et de fréquence cardiaque.RésultatsChez les volontaires sains, la valeur stable moyenne (écart interquartile [ÉIQ]) la plus basse de SctO2 en PAl était 69 [66-71] %. Un changement en PAs a provoqué une réduction, faible mais significative d’un point de vue statistique, de la valeur médiane [ÉIQ] la plus basse de SctO2 à 67 [65-70] % (P = 0,028 comparativement aux valeurs de base). Cette réduction a été associée à une augmentation de la tension artérielle médiane [ÉIQ] de 83 [78-88] mmHg en PAl à 85 [81-93] mmHg en PAs (P < 0,001 comparativement aux valeurs de base). Chez les patients subissant une chirurgie en PAs, la valeur médiane [ÉIQ] stable la plus basse de SctO2 était de 55 [51-59], soit significativement plus basse (P < 0,001) que la valeur médiane [ÉIQ] stable la plus basse telle que mesurée chez les patients en DL (66 [62-69] %). La plupart des patients du groupe PAs (57 %) ont montré des valeurs de SctO2 ≤ 55 % et/ou une réduction ≥ 20 % par rapport aux valeurs de base (57 %) comparativement au groupe DL (5 % et 6 %, respectivement; P < 0,001 pour chaque comparaison).ConclusionPlus de 55 % des patients subissant une arthroscopie de l’épaule dans le groupe PAs ont subi des épisodes de désaturation cérébrale. Chez les volontaires sains n’ayant pas subi d’anesthésie, aucun épisode de désaturation n’a été observé. L’importance clinique de ces résultats nécessite des recherches plus approfondies.

Cerebral saturation monitoring during cardiopulmonary resuscitation should be used as dynamic, rather than static, information

With great interest we read the paper of Parnia et al.1 The uthors report a significantly higher overall mean rSO2 in patients ith return of spontaneous circulation (ROSC) in comparison with on-survivors (respectively 35 ± 5 vs 18 ± 0.4). First of all, both hese values are extremely low, despite the fact that all patients ad in-hospital cardiac arrest, and shorter delays to treatment (and igher overall mean rSO2) are expected compared to patients with ut of hospital arrest.2 The reason for these low values might be elated to the used near-infrared spectroscopy (NIRS) technology INVOS® is a relative O2 saturation monitoring). Secondly, the difference in rSO2 between survivors and nonurvivors is the highest during the final 5 min of resuscitation. This s not a surprising observation, since increasing rSO2 is a precuror of the onset of ROSC and at ROSC, the difference in rSO2 is or sure the greatest compared to rSO2 values in patients who ever had ROSC (and therefore worse hemodynamics without any ncrease in rSO2 during the whole cardiopulmonary resuscitation CPR)). We are not sure whether the slow increase in rSO2 observed efore ROSC might not be explained by the use of a “relative” NIRS echnology (with a proprietary averaging algorithm), not providing absolute” saturation values. The authors confirmed that their findings indicate that rSO2 in ardiac arrest is a dynamic measurement and that any decrease or

Regional cerebral saturation monitoring during withdrawal of life support until death

AIMS The aim of this pilot study was to explore the regional cerebral oxygen saturation (rSO2) during the process of dying in Intensive Care Unit (ICU) patients in whom it was decided to withdraw life support. METHODS Regional cerebral saturation was measured from the moment active treatment was stopped until the moment of death, defined as the onset of asystole. Simultaneously, heart rate and arterial blood pressure were recorded using a radial arterial catheter. Baseline rSO2 values were calculated as mean values over one hour in stable haemodynamic conditions immediately after the decision to withdraw life support. RESULTS Cerebral saturation was measured in six dying ICU patients. The mean age of patients was 64year. The median baseline rSO2 value was 64% (58%-68%). At time of death, median rSO2 was 33% (7%-40%). The median decrease in rSO2 from baseline until death was 31% (25%-45%). The median decrease in rSO2 observed during the last hour before time of death was 20% (12%-31%). CONCLUSION A continuous and patient specific decrease in rSO2 was observed in all patients with a simultaneous decrease in MAP. However, the absolute rSO2 value at moment death was clinically determined, had a broad range, indicating that there is no clear cut-off rSO2 value for death probably due to the heterogeneity of the studied population. Taken together, these observations highlight the importance of following trends and comparing rSO2 values in the cardiac arrest setting.

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.