Gender disparities in patients undergoing extracorporeal cardiopulmonary resuscitation

Introduction

The use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) in extracorporeal cardiopulmonary resuscitation (eCPR) has emerged as a treatment option for selected patients who are experiencing refractory cardiac arrest (CA). In the light of increasing availability, the analyses of outcome-relevant predisposing characteristics are of growing importance. We evaluated the prognostic influence of gender in patients presenting with out-of-hospital cardiac arrest (OHCA) treated with eCPR.

Methods

We retrospectively analysed the data of 377 consecutive patients treated for OHCA using eCPR in our cardiac arrest centre from January 2016 to December 2022. The primary outcome was defined as the survival of patients until they were discharged from the hospital, with a favourable neurological outcome [cerebral performance category (CPC) score of ≤2]. Statistical analyses were performed using baseline comparison, survival analysis, and multivariable analyses.

Results

Out of the 377 patients included in the study, 69 (21%) were female. Female patients showed a lower prevalence rate of pre-existing coronary artery disease (48% vs. 75%, p < 0.001) and cardiomyopathy (17% vs. 34%, p = 0.01) compared with the male patients, while the mean age and prevalence rate of other cardiovascular risk factors were balanced. The primary reason for CA differed significantly (female: coronary event 45%, pulmonary embolism 23%, cardiogenic shock 17%; male: coronary event 70%, primary arrhythmia 10%, cardiogenic shock 10%; p = 0.001). The prevalence rate of witnessed collapse (97% vs. 86%; p = 0.016) and performance of bystander CPR (94% vs. 85%; p = 0.065) was higher in female patients. The mean time from collapse to the initiation of eCPR did not differ between the two groups (77 ± 39 min vs. 80 ± 37 min; p = 0.61). Overall, female patients showed a higher percentage of neurologically favourable survival (23% vs. 12%; p = 0.027) despite a higher prevalence of procedure-associated bleeding complications (33% vs. 16%, p = 0.002). The multivariable analysis identified a shorter total CPR duration (p = 0.001) and performance of bystander CPR (p = 0.03) to be associated with superior neurological outcomes. The bivariate analysis showed relevant interactions between gender and body mass index (BMI).

Conclusion

Our analysis suggests a significant survival benefit for female patients who obtain eCPR, possibly driven by a higher prevalence of witnessed collapse and bystander CPR. Interestingly, the impact of patient age and BMI on neurologically favourable outcome was higher in female patients than in male patients, warranting further investigation.

Prognostic influence of mechanical cardiopulmonary resuscitation on survival in patients with out-of-hospital cardiac arrest undergoing ECPR on VA-ECMO

Introduction

The use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) in extracorporeal cardiopulmonary resuscitation (ECPR) in selected patients after out-of-hospital cardiac arrest (OHCA) is an established method if return of spontaneous circulation cannot be achieved. Automated chest compression devices (ACCD) facilitate transportation of patients under ongoing CPR and might improve outcome. We thus sought to evaluate prognostic influence of mechanical CPR using ACCD in patients presenting with OHCA treated with ECPR including VA-ECMO.

Methods

We retrospectively analyzed data of 171 consecutive patients treated for OHCA using ECPR in our cardiac arrest center from the years 2016 to 2022. A Cox proportional hazards model was used to identify characteristics related with survival.

Results

Of the 171 analyzed patients (84% male, mean age 56 years), 12% survived the initial hospitalization with favorable neurological outcome. The primary reason for OHCA was an acute coronary event (72%) followed by primary arrhythmia (9%) and non-ischemic cardiogenic shock (6.7%). In most cases, the collapse was witnessed (83%) and bystander CPR was performed (83%). The median time from collapse to VA-ECMO was 81 min (Q1: 69 min, Q3: 98 min). No survival benefit was seen for patients resuscitated using ACCD. Patients in whom an ACCD was used presented with overall longer times from collapse to ECMO than those who were resuscitated manually [83 min (Q1: 70 min, Q3: 98 min) vs. 69 min (Q1: 57 min, Q3: 84 min), p = 0.004].

Conclusion

No overall survival benefit of the use of ACCD before ECPR is established was found, possibly due to longer overall CPR duration. This may arguably be because of the limited availability of ACCD in pre-clinical paramedic service at the time of observation. Increasing the availability of these devices might thus improve treatment of OHCA, presumably by providing efficient CPR during transportation and transfer.

Hemadsorption treatment for antithrombotic drug removal in emergency cardiac surgery – cost-benefit analysis comparing patient outcomes

Background

Intraoperative hemadsorption is indicated for ticagrelor and rivaroxaban removal in patients undergoing urgent cardiac surgery and has been previously shown to reduce bleeding complications. However, whether this application is cost effective is currently unknown.

Methods

Between June 2017 and June 2021, we evaluated the outcomes of 72 consecutive patients (age 65±11 years) with acute coronary syndrome (ACS) pretreated with ticagrelor who underwent urgent coronary artery bypass grafting (CABG) at our institution. Intraoperative hemoadsorption (IH) was used in all cases (IH-Pat). We estimated the mean cost per patient, and a bootstrap analysis was performed based on individual data from the case series. We compared the results with “historical patients” who were operated under the same conditions between June 2015 and June 2017 but without IH (n=22).

Results

Bilateral internal mammary artery (BIMA) was used in 67.7% of all cases. Use of IH was associated with significantly shorter operation times (277±65 min vs. 320±75 min; P=0.014) and significantly less postoperative 24-hours chest tube drainage (277±65 mL vs. 866±262 mL; P&lt;0.001). Only two rethoracotomies (2.8%) had to be performed. In addition, patients operated without IH required significantly more blood products and had a significantly higher rate of rethoracotomy, resulting in longer ICU stays. The variable that had the highest impact on the level of cost savings was the operation duration. The overall cost saving with IH were calculated at over 4200±1100€ with operation time, ICU stay and blood product costs being the top contributors.

Conclusions

The results suggest that the clinical benefits derived from IH in ticagrelor-treated patients requiring urgent cardiac surgery patients could result in significant cost savings of over 4200±1100 € per patient.

Funding Acknowledgement

Type of funding sources: None.

A comparison of blind intubation with the intubating laryngeal mask FASTRACH™ and the intubating laryngeal mask Ambu Aura-i™ a prospective randomised clinical trial

Background

The intubating laryngeal mask Fastrach™ is considered a gold standard for blind intubation as well as for fibreoptic guided intubation via a laryngeal mask. Recently, a single use version of the mask has been introduced. We compared the Fastrach single use with the new, low-priced single use intubating laryngeal mask Ambu Aura-i™.

We hypothesised that the LMA Ambu Aura-i and the LMA Fastrach are comparable with respect to success rates for mask placement and blind tracheal intubation through the LMA device.

Methods

A prospective, randomised clinical trial. University Hospital Schleswig-Holstein, Campus Kiel, from April 2011 to April 2012.

Eighty patients undergoing general anaesthesia with planned tracheal intubation were randomised and enrolled in the study. Blind intubation was performed with either laryngeal mask using two different tracheal tubes (Rüsch Super Safety Silk™ and LMA ETT™). A crossover-design was performed after an unsuccessful procedure.

Primary outcome measure was the overall success rate of blind intubation. Secondary outcome measures were the time to the first adequate ventilation, a subjective handling score, and a fibreoptic control of placement, as well as the success rate of mask placement, time for mask removal after successful intubation, differences in airway leak pressure, and the incidence of postoperative sore throat and hoarseness.

Results

The success rate of tracheal intubation with the Fastrach for the first and second attempt was significantly better compared with the Ambu Aura-i. Tracheal intubation was also significantly faster (14.1 s. ±4.4 versus 21.3 s. ±9.0; p < 0.01), and the time interval for mask removal after successful intubation was significantly shorter using the Fastrach device (24.0 s. ±8.2 versus 29.4 s. ±7.5; p < 0.001). There were no significant differences between groups regarding the incidence of postoperative sore throat and hoarseness.

Conclusion

Both laryngeal mask devices are suitable for ventilation and oxygenation. Blind intubation remains the domain of the LMA Fastrach, the Ambu Aura-i is not suitable for blind intubation.

Trial registration

Clinicaltrials.gov Identification Number NCT03109678, retrospectively registered on April 12, 2017.

CaRdiac Arrest Survival Score (CRASS) - A tool to predict good neurological outcome after out-of-hospital cardiac arrest

AIM

The aim of this study was to develop a score to predict the outcome for patients brought to hospital following out-of-hospital cardiac arrest (OHCA).

METHODS

All patients recorded in the German Resuscitation Registry (GRR) who suffered OHCA 2010-2017, who had ROSC or ongoing CPR at hospital admission were included. The study population was divided into development (2010-2016: 7985) and validation dataset (2017: 1806). Binary logistic regression analysis was used to derive the score. The probability of hospital discharge with good neurological outcome was defined as 1/(1 + e^-X), where X is the weighted sum of independent variables.

RESULTS

The following variables were found to have a significant positive (+) or negative (-) impact: age 61-70 years (-0·5), 71-80 (-0·9), 81-90 (-1·3) and > = 91 (-2·3); initial PEA (-0·9) and asystole (-1·4); presumable trauma (-1·1); mechanical CPR (-0·3); application of adrenalin > 0 - < 2 mg (-1·1), 2 - <4 mg (-1·6), 4 - < 6 mg (-2·1), 6 - < 8 mg (-2·5) and > = 8 mg (-2·8); pre emergency status without previous disease (+0·5) or minor disease (+0·2); location at nursing home (-0·6), working place/school (+0·7), doctor's office (+0·7) and public place (+0·3); application of amiodarone (+0·4); hospital admission with ongoing CPR (-1·9) or normotension (+0·4); witnessed arrest (+0·6); time from collapse until start CPR 2 - < 10 min (-0·3) and > = 10 min (-0·5); duration of CPR <5 min (+0·6). The AUC in the development dataset was 0·88 (95% CI 0·87-0·89) and in the validation dataset 0·88 (95% CI 0·86-0·90).

CONCLUSION

The CaRdiac Arrest Survival Score (CRASS) represents a tool for calculating the probability of survival with good neurological function for patients brought to hospital following OHCA.

Measurement of the nociceptive balance by Analgesia Nociception Index and Surgical Pleth Index during sevoflurane-remifentanil anesthesia

BACKGROUND

Evaluation of the nociception-anti-nociception balance during anesthesia is still challenging and routinely based on clinical criteria such as movement or vegetative response. Recently, the Analgesia Nociception Index (ANI) derived from heart rate variability and the Surgical Pleth Index (SPI) derived from photoplethysmographic signal were introduced for quantification of the analgesic component of anesthesia.

METHODS

After obtaining informed consent, we studied twenty-four patients (ASA I-II) scheduled for elective surgery during induction of anesthesia with sevoflurane and a stepwise increase of remifentanil effect site concentrations. Insertion of a laryngeal mask, tetanic stimulations as well as tracheal intubation were studied as nociceptive events.

RESULTS

A total of 120 events were analysed. Both ANI and SPI enabled consistent detection of nociceptive events by significant changes (∆). Further, ∆ANI and ∆SPI significantly indicated patient's movement after tetanic stimulation with a prediction probability of 0.74 and 0.84.

CONCLUSION

Non-invasive monitoring of ANI and SPI reflected nociceptive stimulation during sevoflurane-remifentanil anesthesia and therefore may indicate the nociception - anti-nociception balance. Whether guidance of anesthesia by these variables will improve anesthesia care during surgery needs to be further evaluated.

Validation study of Nexfin® continuous non-invasive blood pressure monitoring in critically ill adult patients

BACKGROUND

Nexfin® (BMEYE, Amsterdam, The Netherlands) is a totally non-invasive blood pressure and cardiac output (CO) monitor based on finger arterial pulse contour analysis.

METHODS

We performed an open observational study in a mix of medical-surgical-burns critically ill patients (N.=45) to validate Nexfin obtained blood pressures (MAPnex) against PiCCO (MAPfem) derived blood pressure measurements. MAPnex, MAPfem and corresponding systolic (SBP) and diastolic (DBP) blood pressures were measured continuously and registered with a 2 hour interval during the 8-hour study period. Statistical analysis was performed by Pearson regression, Bland and Altman, Concordance plot and Polar plot analysis.

RESULTS

MAPnex shows excellent correlation with MAPfem (R² 0.88, mean bias ± LA -2.3±12.4 mmHg, 14.7% error) and may be used interchangeably with invasive monitoring. The excellent MAPnex -MAPfem correlation was preserved in subgroup analysis for patients with severe hypotension, high systemic vascular resistance, low CO, hypothermia and in patients supported by inotropic/vasopressive agents. MAPnex is able to follow changes in MAPfem during the same time interval (level of concordance 85.5%). Nexfin SBP and DBP show significant correlation with PiCCO but the criteria for interchangeability were not met. Finally, polar plot analysis showed that trending capabilities were excellent when changes in MAPnex (ΔMAPnex) were compared to ΔMAPfem (96.1% of changes were within the level of 10% limits of agreement).

CONCLUSION

In this sample of critically ill patients we found a good correlation between MAPnex and invasive blood pressures obtained by PiCCO.

Remote preconditioning and major clinical complications following adult cardiovascular surgery: systematic review and meta-analysis

BACKGROUND

A number of 'proof-of-concept' trials suggest that remote ischaemic preconditioning (RIPC) reduces surrogate markers of end-organ injury in patients undergoing major cardiovascular surgery. To date, few studies have involved hard clinical outcomes as primary end-points.

METHODS

Randomised clinical trials of RIPC in major adult cardiovascular surgery were identified by a systematic review of electronic abstract databases, conference proceedings and article reference lists. Clinical end-points were extracted from trial reports. In addition, trial principal investigators provided unpublished clinical outcome data.

RESULTS

In total, 23 trials of RIPC in 2200 patients undergoing major adult cardiovascular surgery were identified. RIPC did not have a significant effect on clinical end-points (death, peri-operative myocardial infarction (MI), renal failure, stroke, mesenteric ischaemia, hospital or critical care length of stay).

CONCLUSION

Pooled data from pilot trials cannot confirm that RIPC has any significant effect on clinically relevant end-points. Heterogeneity in study inclusion and exclusion criteria and in the type of preconditioning stimulus limits the potential for extrapolation at present. An effort must be made to clarify the optimal preconditioning stimulus. Following this, large-scale trials in a range of patient populations are required to ascertain the role of this simple, cost-effective intervention in routine practice.

Propofol EC50 for inducing loss of consciousness is lower in the luteal phase of the menstrual cycle

BACKGROUND

Varying levels of female sex hormones during the menstrual cycle were found to influence the central nervous system. The goal of the present study was to investigate whether the median (50%) effective effect-concentration (EC50) of propofol inducing loss of consciousness (LOC) varies between the luteal and the follicular phases of the menstrual cycle.

METHODS

Twenty-two patients (follicular phase) and 20 patients (luteal phase) undergoing gynaecological procedures under general anaesthesia were enrolled on the study. Anaesthesia was conducted with a target-controlled infusion (TCI) of propofol. The initial target effect-site propofol concentration (Ceprop) was 3.5 µg ml(-1) and was adjusted stepwise by 0.5 µg ml(-1) at 4 min intervals by an up-down sequential method to reach LOC. Anaesthesia was maintained with a propofol TCI guided by the bispectral index. The correlation between female sex hormones and predicted Ceprop at the time of LOC was analysed and emergence time from anaesthesia was recorded.

RESULTS

Propofol EC50 to induce LOC was higher in patients in the follicular phase than those in the luteal phase (4.17 vs 3.58 µg ml(-1), P<0.05). Progesterone correlated significantly with Ceprop at LOC. Emergence time was also longer in the follicular group than in the luteal group (6.5 vs 5.0 min, P<0.05).

CONCLUSIONS

During general anaesthesia, patients in the luteal phase of the menstrual cycle had a lower propofol EC50 for LOC and a shorter emergence time compared with those in the follicular phase. Differences in progesterone levels between menstrual phases may contribute to these anaesthetic effects. Registry number of clinical trial ChiCTR-RCH-12002755.

Effect of propofol and sevoflurane on acid-base balance during pediatric heart catheterization

BACKGROUND

Propofol is routinely used for anesthesia during pediatric heart catheterization. Propofol infusion syndrome (PRIS) is a rare, but often fatal complication mainly defined as bradycardia with progress to asystolia during propofol infusion. Metabolic acidosis is regarded as an early warning sign of PRIS. In this study the effect of propofol and sevoflurane on serum base excess, pH and lactate have been examined during pediatric heart catheterization.

METHODS

In this prospective randomised study 42 children have been anesthetised for pediatric heart catheterization with propofol (N.=22) or sevoflurane (N.=20) with ethic committee approval. Base excess, pH and lactate were measured by blood gas analysis at the beginning, during and at the end of the procedure. Changes relative to baseline were analysed by paired t-Test with correction for multiple testing. The study was powered to detect a difference of 1.5 mmol.L-1 for base excess and lactate.

RESULTS

Base excess (-2.59 [2.33] vs. -4.48 [2.88], P=0.0004, mean [standard deviation]) and pH (7.39 [0.05] vs. 7.36 [0.06], P=0.0008,) changed significantly in in the propofol group but not in the sevoflurane group. The number of patients with base excess < 5.0 increased in the propofol group only from 2 to 10 (P=0.016). Lactate decreased in both groups (1.1 [0.3] vs. 0.9 [0.2], P=0.003 for sevoflurane and 1.0 [0.3] vs. 0.8 [0.3], P=0.0004 for propofol).

CONCLUSION

Propofol but not sevoflurane had an effect on base excess and pH during pediatric heart catheterization.

Influence of nociceptive stimulation on analgesia nociception index (ANI) during propofol-remifentanil anaesthesia

BACKGROUND

Measurement of the balance between nociception and anti-nociception during anaesthesia is challenging and not yet clinically established. The Surgical pleth index (SPI), derived from photoplethysmography, was proposed as a surrogate measure of nociception. Recently, the analgesia nociception index (ANI) derived by heart rate (HR) variability was developed. The aim of the present study was to challenge the ability of ANI compared with SPI to detect standardized noxious stimulation during propofol-remifentanil anaesthesia.

METHODS

After Ethics approval and informed consent, 25 patients were anaesthetized with propofol [bispectral index (BIS) 30-60]. A laryngeal mask (LMA) was inserted and remifentanil stepwise increased to effect-site concentrations (Ce(remi)) of 0, 2, and 4 ng ml(-1). At each step, tetanic stimulation (STIM) was applied. ANI, SPI, BIS, HR, and mean arterial pressure (MAP) were obtained before and after LMA insertion and each STIM. Analysis was performed using Wilcoxon rank tests and calculation of prediction probabilities (P(K)).

RESULTS

ANI and SPI, but not BIS, HR, or MAP, were significantly (P<0.05) changed at all examined steps. ANI response to STIM was (median [IQR]) -24 [-12-35], -30 [-20 - -40] and -13 [-5 - -27] at 0, 2 and 4 ng ml(-1) Ce(remi). However, prediction of movement to STIM was not better than by chance, as P(K) values were 0.41 (0.08) for ANI and 0.62 (0.08) for SPI.

CONCLUSIONS

The two variables, ANI and SPI, enabled consistent reflection of stimulation during propofol-remifentanil anaesthesia. Nevertheless, ANI and SPI may improve detection but not prediction of a possible inadequate nociception-anti-nociception balance. Clinicaltrials.gov Identifier. NCT01522508.

A comparison of continuous non-invasive arterial pressure with invasive radial and femoral pressure in patients undergoing cardiac surgery

BACKGROUND

Non-invasive continous monitoring of finger arterial pressure has gained increasing interest. The aim of the present study was to compare the accuracy of non-invasive reconstructed brachial artery pressure by the Nexfin™ device (NFAP) with invasive femoral (IFAP) and radial (IRAP) artery pressure before and after cardiopulmonary bypass (CPB).

METHODS

Fifty patients scheduled for elective coronary surgery were studied before and after CPB, respectively. Each patient was monitored with the non-invasive system, and both an indwelling femoral and radial arterial catheter. A passive leg raising maneuver was also performed before and after CPB. Measurements included mean (MAP), systolic (SAP) and diastolic (DAP) arterial pressure by NFAP (MAP,SAP,DAP(NFAP)), IFAP (MAP,SAP,DAP(IFAP)) and IRAP (MAP,SAP,DAP(IRAP)). Percentage changes of MAP for all measurement sites were also calculated.

RESULTS

There was a moderate correlation between MAP(NFAP) and MAP(IFAP) both before (r=0.64, P<0.0001) and after (r=0.57, P<0.0001) CPB, with a percentage error (PE) of 29% and 27%, respectively. Correlation coefficients between MAP(NFAP) and MAP(IRAP) were r=0.53, P<0.0001 (PE 34%) before and r=0.54, P<0.0001 (PE 29%) after CPB. There was a significant correlation in percentage changes between ∆MAP(NFAP) and ∆MAP(IFAP) before (r=0.70, P<0.0001) and after (r=0.71, P<0.0001) CPB and for ∆MAP(NFAP) and ∆MAP(IRAP) (r=0.67, P<0.0001; r=0.74, P<0.0001), respectively.

CONCLUSION

Non-invasive, reconstructed brachial artery pressure showed moderate correlation compared with both invasive femoral and radial artery pressure. Furthermore, the non-invasive monitoring system was able to reflect percentage changes in mean arterial pressure in a moderate fashion.

Effect of propofol on hypoxia re-oxygenation induced neuronal cell damage in vitro*

Propofol may protect neuronal cells from hypoxia re-oxygenation injury, possibly via an antioxidant actions under hypoxic conditions. This study investigated the molecular effects of propofol on hypoxia-induced cell damage using a neuronal cell line. Cultured human IMR-32 cells were exposed to propofol (30 μm) and biochemical and molecular approaches were used to assess cellular effects. Propofol significantly reduced hypoxia-mediated increases in lactate dehydrogenase, a marker of cell damage (mean (SD) for normoxia: 0.39 (0.07) a.u.; hypoxia: 0.78 (0.21) a.u.; hypoxia+propofol: 0.44 (0.17) a.u.; normoxia vs hypoxia, p<0.05; hypoxia vs hypoxia+propofol, p<0.05), reactive oxygen species and hydrogen peroxide. Propofol also diminished the morphological signs of cell damage. Increased amounts of catalase, which degrades hydrogen peroxide, were detected under hypoxic conditions. Propofol decreased the amount of catalase produced, but increased its enzymatic activity. Propofol protects neuronal cells from hypoxia re-oxygenation injury, possibly via a combined direct antioxidant effect along with induced cellular antioxidant mechanisms.

Engineering polarization rotation in a ferroelectric superlattice

A key property that drives research in ferroelectric perovskite oxides is their strong piezoelectric response in which an electric field is induced by an applied strain, and vice versa for the converse piezoelectric effect. We have achieved an experimental enhancement of the piezoelectric response and dielectric tunability in artificially layered epitaxial PbTiO(3)/CaTiO(3) superlattices through an engineered rotation of the polarization direction. As the relative layer thicknesses within the superlattice were changed from sample to sample we found evidence for polarization rotation in multiple x-ray diffraction measurements. Associated changes in functional properties were seen in electrical measurements and piezoforce microscopy. The results demonstrate a new approach to inducing polarization rotation under ambient conditions in an artificially layered thin film.

Airway management in pediatric patients using the Glidescope Cobalt®: a feasibility study

BACKGROUND

Video laryngoscopes are claimed to improve airway management. Several studies showed an equal or better glottic view using the Glidescope® compared with direct laryngoscopy in adults and in paediatric patients. Many case reports also described successful intubation in patients with a difficult airway. The Glidescope Cobalt® is a modified Glidescope® with a disposable sheath. Data on clinical application in paediatric patients is insufficient.

METHODS

Twenty-four pediatric patients with a mean age of 27 months [range, 1-142] undergoing general anesthesia were included into this feasibility study. Cormack and Lehane grade was evaluated using a Macintosh blade. Tracheal intubation was performed using the Glidescope Cobalt®. Number of attempts, time to intubation, Cormack and Lehane (C&L) grade and a subjective score were noted for both a resident and an attending anesthesiologist.

RESULTS

With the Glidescope Cobalt® the C&L grade improved in all patients with grade 2 or 3 to 1 and deteriorated in one case from C&L grade 1 to 2. The C&L grade remained unchanged in 15 patients (62.5%). C&L grades between resident and attending anesthesiologist were equal. Tracheal intubation was successful in 92% with a stylet-armed tube and in 8% using an unarmed tube with a Magill forceps, respectively. Time to intubation was median 50.5 [range, 22-93] seconds.

CONCLUSION

The Glidescope Cobalt® presented suitable for use in children. C&L grade was significantly improved in all patients with a C&L grade of 2 or 3. Especially for educational purposes in pediatric anesthesia it provides a good view for all participants.

The shaker potassium channel is no target for xenon anesthesia in short-sleeping Drosophila melanogaster mutants

Background. Xenon seems to be an ideal anesthetic drug. To explore if next to the antagonism at the NMDA-receptor other molecular targets are involved, we tested the xenon requirement in short sleeping Drosophila shaker mutants and in na[har³⁸]. Methods. The Drosophila melanogaster strains wildtype Canton-S, na[har³⁸], sh¹⁰² and sh^mns, were raised and sleep was measured. Based on the response of the flies at different xenon concentrations, logEC50 values were calculated. Results. The logEC50-values for WT Canton-S were 1.671 (1.601–1.742 95%-confidence intervall; n = 238; P versus sh¹⁰² > 0,05), for sh^mns 1.711 (1.650–1.773; n = 242; P versus WT Canton-S > 0,05). The logEC50-value for sh¹⁰² was 1.594 (1.493–1.694; n = 261; P versus sh^mns > 0.05). The logEC-value of na[har³⁸] was 2.076 (1.619–2.532; n = 207; P versus sh^mns < 0.05, versus sh¹⁰² < 0.05, versus WT Canton-S < 0.05). P values for all shaker mutants were P > 0.05, while na[har³⁸] was found to be hyposensitive compared to wildtype (P < 0.05). Conclusions. The xenon requirement in Drosophila melanogaster is not influenced by a single gene mutation at the shaker locus, whereas a reduced expression of a nonselective cation channel leads to an increased xenon requirement. This supports the thesis that xenon mediates its effects not only via an antagonism at the NMDA-receptor.

[Intraoperative surgical and anesthesiological problems and the consequences for surgery]

Although the procedures for severe intraoperative complications have largely been defined, in everyday life less dramatic but equally important problems and issues arise which are controversially debated between treating surgeons and the anesthesiologists. Preoperative anemia, transfusion therapy, fluid management, patient positioning, hypothermia and neuromuscular blockade are the focus of the occasionally conflicting interests of anesthesiologists and surgeons. Good reciprocal communication and mutual understanding are a requirement for proactive management of complications. The overall objective is the reduction of intraoperative risks thereby reducing morbidity and mortality. This can be achieved through modern fluid management, blood conserving techniques and maintenance of normothermia. Surgeons further require an optimal view during minimally invasive surgery even by complex patient positioning and adequate neuromuscular blockade.

Electrophysiologic neuromonitoring during repair of the thoracoabdominal aorta by anesthesiologists

BACKGROUND

Surgical repair of the thoracoabdominal aorta is associated with risk of spinal ischemia. Electrophysiologic neuromonitoring reduces this risk, but is usually performed by neurophysiologists not always available. In this study repair of the thoracoabdominal aorta monitored by anesthesiologists has been investigated.

METHODS

Somatosensory and transcranial electrical motor evoked potentials were monitored in 20 patients. A lumbar intraspinal fluid drainage was inserted. Dacron graft replacement of the aorta was performed by sequentially clamping during partial cardiopulmonary bypass. Loss or decrease of amplitudes of evoked potentials of more than 50% prompted reinsertion of spinal arteries in the graft.

RESULTS

One patient not monitored with motor evoked potentials due to indwelling cardiac pacemaker had postoperative paraplegia. Somatosensory and motor evoked potentials were recordable in all other patients. Two patients died during surgery, one patient died postoperatively. No surviving patient monitored with somatosensory and motor evoked potentials had neurologic deficits.

CONCLUSION

Electrophysiologic neuromonitoring during surgical repair of the descending aorta can be successfully provided by anesthesiologists and should be predominately encouraged where neurophysiologists are not available due to organizational or financial shortcomings.

Clinically relevant asymmetry of bispectral index during recovery from anaesthesia for ear-nose-throat surgery in adults and children

This study investigates the incidence of clinically relevant asymmetry in bispectral index readings from different sides of the skull (using two monitors) during ear-nose-throat surgery in 42 adults and 46 children. A unilateral increase or decrease > 10% from baseline was defined as an 'asymmetry'. Asymmetry followed by movement after stimulation was defined as a 'clinically relevant asymmetry'. Asymmetry occurred in 39 out of 42 adults (93%) and in 20 out of 46 children (44%) during surgery and in 24 out of 42 adults (57%) and in 17 out of 46 children (37%) during recovery. Clinically relevant asymmetry was observed in 5 out of 42 adults (12%) and 6 out of 46 children (13%). The incidence of asymmetry was higher in adults during surgery (p = 0.0002). In conclusion, clinically relevant bispectral index asymmetry has been observed in > 10% of paediatric and adult anaesthesia and may have clinical implications. You can respond to this article at http://www.anaesthesiacorrespondence.com.

Accuracy of the pleth variability index to predict fluid responsiveness depends on the perfusion index

BACKGROUND

Respiratory variations in plethysmographic waveform amplitudes derived from pulse oximetry are believed to predict fluid responsiveness. The non-invasive pleth variability index (PVI) is a variable based on the calculation of changes in the perfusion index (PI). The aim of the following study was to examine whether the predictive power of PVI depends on different values of PI.

METHODS

Eighty-one patients undergoing elective coronary artery surgery were studied before operation: at baseline after induction of anaesthesia and during passive leg raising (PLR). Each patient was monitored with central venous pressure (CVP), the PiCCO monitor and the non-invasive Masimo monitoring system. Stroke volume index by transpulmonary thermodilution (SVI(TPTD)), pulse pressure variation (PPV), stroke volume variation (SVV) and systemic vascular resistance index (SVRI) were measured using the PiCCO monitoring system. PI and PVI were obtained by pulse oximetry.

RESULTS

Responders were defined to increase their SVI(TPTD) >15% after PLR. The highest area under the curve (AUC) was found for PPV (AUC: 0.83, P<0.0001) and SVV (AUC: 0.72, P=0.002), in contrast to PVI (AUC: 0.60, P=0.11) and CVP (AUC: 0.60, P=0.13). The accuracy of PVI to predict fluid responsiveness was improved on analysing patients with higher PI values. PI of about 4% (n=45) achieved statistical significance (AUC: 0.72, P=0.01).

CONCLUSION

The PVI was not able to predict fluid responsiveness with sufficient accuracy. In patients with higher perfusion states, the PVI improved its ability to predict haemodynamic changes, strongly suggesting a relevant influence of the PI on the PVI.

Assessment of left ventricular systolic function during acute myocardial ischemia: a comparison of transpulmonary thermodilution and transesophageal echocardiography

BACKGROUND

The PiCCO system provides different variables of cardiac function: the cardiac function index (CFI), the global ejection fraction (GEF) and the maximal pressure developed by the left ventricle (dP/dtMax). The purpose of this study was to investigate the ability of these variables to predict impaired left ventricular ejection fraction (LVEF) derived by transesophageal echocardiography during acute myocardial ischemia.

METHODS

In this prospective experimental study, fifteen pigs (28-34 kg) were anesthetized, mechanically ventilated and subjected to left anterior descending (LAD) coronary artery occlusion. PiCCO-derived variables and LVEF were obtained 5, 10, 15, and 20 minutes after LAD occlusion. Receiver operating characteristics analysis was performed to assess the ability of PiCCO-derived parameters to estimate LVEF ≤40% and ≤50%.

RESULTS

LAD occlusion induced a decrease in PiCCO-derived variables and LVEF (P<0.001 for each). Significant correlations were found between LVEF and CFI (r=0.59, P<0.001), GEF (r=0.64, P<0.001), dP/dtMax (r=0.36, P<0.001), and cardiac output (r=0.25, P=0.028). The area under the receiver operating characteristics curve for the estimation of LVEF ≤40% and ≤50% was 0.80 and 0.79 for CFI (P=0.009, P<0.001), 0.86 and 0.78 for GEF (P=0.002, P<0.001), 0.76 and 0.68 for dP/dtMax (P=0.033, P=0.012), and 0.57 and 0.58 for cardiac output (P=0.554, P=0.259).

CONCLUSION

Cardiac function indices permit the bedside quantification of left ventricular systolic function during acute myocardial ischemia in pigs. Therefore, the PiCCO system may represent a valuable technique for cardiovascular monitoring, particularly for detecting acute left ventricular systolic dysfunction due to myocardial ischemia.

Surgical stress index in response to pacemaker stimulation or atropine

BACKGROUND

The surgical stress index (SSI) is a new monitoring tool for the assessment of nociception during general anaesthesia. It is calculated based on the heart beat interval and the pulse wave amplitude. Correlation of SSI with nociceptive stimuli and opioid effect-site concentrations has been demonstrated, but the influence of isolated modulation of heart rate (HR) on SSI is still unclear. The aim of this study was to evaluate the effect on SSI of atropine administration and cardiac pacing.

METHODS

In 18 anaesthetized ASA III ICU patients, either repetitive cardiac pacemaker stimulation or administration of atropine (10 microg kg(-1)) was performed, and the effect on SSI, arterial pressure, spectral entropy, and bispectral index was analysed.

RESULTS

Cardiac pacing at 100 beats min(-1) was followed by an increase in SSI from 26 [17-35 (10-41)] to 59 [53-72 (48-78)] {median [inter-quartile range (range)]} (P=0.0006), whereas other variables remained unaffected. Also, atropine administration increased SSI from 27 [20-34 (16-39)] to 58 [48-70 (41-81)] (P=0.007) without significant effect on other variables except HR. A recalibration of SSI during cardiac pacing leads to a significant decrease in SSI to 49 [40-52 (36-57)] (P=0.03), whereas recalibration after atropine administration had no effect.

CONCLUSIONS

SSI values measured in patients receiving atropine or in patients with pacemakers should be interpreted cautiously.

Intrathecal sufentanil decreases the median effective dose (ED50) of intrathecal hyperbaric ropivacaine for caesarean delivery

BACKGROUND

The addition of opioid to local anaesthetics has become a well-accepted practice of spinal anaesthesia for caesarean delivery. Successful caesarean delivery anaesthesia has been reported with the use of a low dose of intrathecal hyperbaric ropivacaine coadministered with sufentanil. This prospective, double-blinded study determined the median effective dose (ED50) of intrathecal hyperbaric ropivacaine with and without sufentanil for caesarean delivery, to quantify the sparing effect of sufentanil on the ED50 of intrathecal hyperbaric ropivacaine.

METHODS

Sixty-four parturients undergoing elective caesarean delivery with combined spinal-epidural anaesthesia were randomized into two groups: Group R (ropivacaine) and Group RS (ropivacaine plus sufentanil 5 microg). The initial dose of ropivacaine was 13 mg in Group R and 10 mg in Group RS. The effective dose was defined as a T(6) level attained within 10 min and no supplemental epidural anaesthetic required during surgery. Effective or ineffective responses determined, respectively, a 0.3 mg decrease or increase of the dose of ropivacaine for the next patient using an up-down sequential allocation.

RESULTS

The ED50 of intrathecal ropivacaine was 11.2 mg [confidence interval (CI) 95%: 11.0-11.6] in Group R vs. 8.1 mg (CI 95%: 7.8-8.3) in Group RS. Motor block was markedly more intense in Group R than in Group RS, and the incidence of shivering was lower in Group RS than in Group R. There were no differences in the onset time of sensory block or motor block, in the incidence of hypotension, nausea and vomiting.

CONCLUSION

Intrathecal sufentanil 5 microg produced a 28% reduction of ED50 of intrathecal hyperbaric ropivacaine for caesarean delivery.

Correlation and agreement between the bispectral index vs. state entropy during hypothermic cardio-pulmonary bypass

BACKGROUND

The bispectral index (BIS) and spectral entropy enable monitoring the depth of anaesthesia. Mild hypothermia has been shown to affect the ability of electroencephalography monitors to reflect the anaesthetic drug effect. The purpose of this study was to investigate the effect of hypothermia during a cardio-pulmonary bypass on the correlation and agreement between the BIS and entropy variables compared with normothermic conditions.

METHODS

This prospective clinical study included coronary artery bypass grafting patients (n=25) evaluating correlation and agreement (Bland-Altman analysis) between the BIS and both spectral and response entropy during a hypothermic cardio-pulmonary bypass (31-34 degrees C) compared with nomothermic conditions (34-37.5 degrees C). Anaesthesia was maintained with propofol and sufentanil and adjusted clinically, while the anaesthetist was blinded to the monitors.

RESULTS

The BIS and entropy values decreased during cooling (P<0.05), but the decrease was more pronounced for entropy variables compared with BIS (P<0.05). The correlation coefficients (bias+/-SD; percentage error) between the BIS vs. spectral state entropy and response entropy were r(2)=0.56 (1+/-11; 42%) and r(2)=0.58 (-2+/-11; 43%) under normothermic conditions, and r(2)=0.17 (10+/-12; 77%) and r(2)=0.18 (9+/-11; 68%) under hypothermic conditions, respectively. Bias was significantly increased under hypothermic conditions (P<0.001 vs. normothermia).

CONCLUSION

Acceptable agreement was observed between the BIS and entropy variables under normothermic but not under hypothermic conditions. The BIS and entropy variables may therefore not be interchangeable during a hypothermic cardio-pulmonary bypass.

A comparison of the i-gel with the LMA-Unique in non-paralysed anaesthetised adult patients

SUMMARY

This study assessed two disposable devices; the newly developed supraglottic airway device i-gel and the LMA-Unique in routine clinical practice. Eighty patients (ASA 1-3) undergoing minor routine gynaecologic surgery were randomly allocated to have an i-gel (n = 40) or LMA-Unique (n = 40) inserted. Oxygen saturation, end-tidal carbon dioxide, tidal volume and peak airway pressure were recorded, as well as time of insertion, airway leak pressure, postoperative sore-throat, dysphonia and dysphagia for each device. Time of insertion was comparable with the i-gel and LMA-Unique. There was no failure in the i-gel group and one failure in the LMA-Unique group. Ventilation and oxygenation were similar between devices. Mean airway pressure was comparable with both devices, whereas airway leak pressure was significantly higher (p < 0.0001) in the i-gel group (mean 29 cmH(2)O, range 24-40) compared with the LMA-Unique group (mean 18 cmH(2)O, range 6-30). Fibreoptic score of the position of the devices was significantly better in the i-gel group. Post-operative sore-throat and dysphagia were comparable with both devices. Both devices appeared to be simple alternatives to secure the airway. Significantly higher airway leak pressure suggests that the i-gel may be advantageous in this respect.

Influence of different remifentanil concentrations on the performance of the surgical stress index to detect a standardized painful stimulus during sevoflurane anaesthesia

BACKGROUND

Although measurement of cerebral hypnotic drug effect and muscle relaxation is common clinical routine during anaesthesia, a reliable measurement of the neurophysiological effects evoked by a painful stimulus is still missing. Recently, the surgical stress index (SSI) has been introduced as a surrogate measure of 'nociception'. The present study aimed to examine the influence of increasing remifentanil concentrations on the ability of SSI to detect a standardized painful stimulus during sevoflurane anaesthesia.

METHODS

Twenty-four patients received incremental or decremental doses of 0, 2, and 4 ng ml(-1) remifentanil effect-site concentration (Ce(remi)) during 0.7 MAC sevoflurane. Painful tetanic stimulation was applied at least 5 min after changing Ce(remi). SSI, heart rate (HR), response entropy (RE), state entropy (SE), RE-SE difference, and bispectral index (BIS) were obtained in each patient before and after stimulation. Further prediction of an author-defined response to painful stimulus was analysed.

RESULTS

SSI and BIS, but not HR, SE, RE, or RE-SE difference were significantly altered after stimulation. Change in SSI (Delta SSI) was significantly dependent on Ce(remi), as Delta SSI was [median (inter-quartile range)] 20 (15-31), 10 (1-19), and 3 (1-10) at 0, 2, and 4 ng ml(-1) Ce(remi). In 10 out of 63 cases, SSI detected response to stimulation, not detected by another variable. SSI was unable to predict movement after stimulation as P(K) value is 0.59 (0.09).

CONCLUSIONS

The SSI response to tetanic stimulation was dependent on the remifentanil concentration.