Dexmedetomidine as a part of general anaesthesia for caesarean delivery in patients with pre-eclampsia: Efficacy and foetal outcome a randomised double-blinded trial

BACKGROUND During general anaesthesia, endotracheal intubation of patients with pre-eclampsia causes stimulation of the sympathetic nervous system and catecholamine release, which may lead to maternal and neonatal complications. OBJECTIVE To attenuate both the stress response and the haemodynamic response to tracheal intubation in patients with pre-eclampsia. DESIGN A randomised, double-blind, controlled study. SETTING Single University Hospital. PATIENTS Sixty patients aged 18 to 45 years with pre-eclampsia receiving general anaesthesia for caesarean section. INTERVENTIONS The patients were randomly allocated to three groups. Groups D1and D2 received an infusion of dexmedetomidine 1 μg kg−1 over the 10 min before induction of general anaesthesia, then 0.4 and 0.6 μg kg−1 h−1 dexmedetomidine, respectively. Group C received equivalent volumes of 0.9% saline. MAIN OUTCOME MEASURES The primary outcome was the effect of dexmedetomidine on mean arterial blood pressure measured before induction of general anaesthesia at 1 and 5 min after intubation, and then every 5 min until 10 min after extubation. The secondary outcomes were blood glucose and serum cortisol (measured before induction of general anaesthesia, and at 1 and 5 min after intubation), postoperative visual analogue pain scores, time to first request for analgesia, the total consumption of analgesia, Ramsay sedation score, maternal and placental vein blood serum levels of dexmedetomidine and neonatal Apgar score at 1 and 5 min. RESULTS At all assessment times, the mean arterial pressures were significantly lower in the dexmedetomidine groups than in the control group. Compared with group C, the heart rate was significantly lower in both groups D1 and D2. In group D2, the heart rate was lower than in group D1. Serum glucose and cortisol were significantly higher in the controls than in either group D1 or D2. Group D2 patients were significantly more sedated on arrival in the recovery room followed by D1. Time to first analgesia was significantly longer in groups D2 and D1 than in group C, and the visual analogue pain scores were significantly lower in groups D1 and D2 than in group C at 1, 2, 3 and 5 h. Total morphine consumption was significantly lower in groups D1 and D2 than in the control group. There was no difference in Apgar scores across the three groups despite significantly higher dexmedetomidine concentrations in group D2 (both maternal and placental vein) than in group D1. CONCLUSION Administration of dexmedetomidine in doses 0.4 and 0.6 μg kg−1 h−1 was associated with haemodynamic and hormonal stability, without causing significant adverse neonatal outcome. TRIAL REGISTRATION Pan African Clinical Trial Registry (PACTR201706002303170), (www.pactr.org). Correspondence to Ashraf M. Eskandr, MD, Department of Anesthesia, ICU and Pain Therapy, Faculty of Medicine, Menoufiya University, 3 Yassin Abd-Elghafar Street, Shibin El-koom, Egypt E-mail: ameskandr@yahoo.com © 2018 European Society of Anaesthesiology

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Low anaesthetic waste gas concentrations in postanaesthesia care unit: A prospective observational study

BACKGROUND Volatile anaesthetics are a potential hazard during occupational exposure, pregnancy or in individuals with existing disposition to malignant hyperthermia. Anaesthetic waste gas concentration in postanaesthesia care units (PACU) has rarely been investigated. OBJECTIVE(S) The current study aims to assess concentrations of volatile anaesthetics in relation to room size, number of patients and ventilator settings in different PACUs. DESIGN A prospective observational study. SETTING Two different PACUs of the Hannover Medical School (Hannover, Germany) were evaluated in this study. The rooms differed in dimensions, patient numbers and room ventilation settings. PATIENTS During the observation period, sevoflurane anaesthesia was performed in 65 of 140 patients monitored in postanaesthesia unit one and in 42 of 70 patients monitored in postanaesthesia unit two. MAIN OUTCOME MEASURES Absolute trace gas room concentrations of sevoflurane measured with a compact, closed gas loop high-resolution ion mobility spectrometer. RESULTS Traces of sevoflurane could be detected in 805 out of 970 samples. Maximum concentrations were 0.96 ± 0.20 ppm in postanaesthesia unit one, 0.82 ± 0.07 ppm in postanaesthesia unit two. Median concentration was 0.12 (0.34) ppm in postanaesthesia unit one and 0.11 (0.28) ppm in postanaesthesia unit two. CONCLUSION Low trace amounts of sevoflurane were detected in both PACUs equipped with controlled air exchange systems. Occupational exposure limits were not exceeded. Correspondence to Dr. Sebastian Heiderich, MD, Clinic of Anaesthesiology and Intensive Care Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany E-mail: heiderich.sebastian@mh-hannover.de © 2018 European Society of Anaesthesiology

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Low perfusion pressure is associated with renal tubular injury in infants undergoing cardiac surgery with cardiopulmonary bypass: A secondary analysis of an observational study

BACKGROUND Earlier work on adults undergoing surgery with cardiopulmonary bypass suggests that there is a close relationship between the lower limit of the cerebral and renal autoregulation pressures. Although cerebral autoregulation during bypass in infants has been extensively investigated, the impact of bypass on kidney function is not well known. It is, nevertheless, acknowledged that the main pathophysiological process involved in cardiac surgery-related kidney damage is tubular injury, and that urine neutrophil gelatinase-associated lipocaline (uNGAL) is a reliable biomarker of injury. OBJECTIVE To identify the most predictive bypass variable for the measurement of renal injury, its threshold value and the most predictive time below that threshold. DESIGN Observational study linking electronically recorded bypass perfusion pressure and oxygen delivery rate with intra-operative uNGAL excretion. Variations in bypass variables were accounted for by their excursions below several thresholds. SETTING French tertiary referral paediatric cardiac centre. PATIENTS A total of 72 infants in whom uNGAL was measured within 1 h of bypass. INTERVENTIONS None. MAIN OUTCOME MEASURE Renal injury, identified by a high creatinine normalised uNGAL concentration (>21.2 μg mmol−1). RESULTS At the end of bypass, 43.75% of infants had high uNGAL. A more than 40% pressure drop below the normal age-standardised mean arterial pressure was associated with high uNGAL. Receiver operating curve [interquartile range] areas were 0.626 [0.501 to 0.752] for a more than 40% drop, and 0.679 [0.555 to 0.804] for a more than 50% drop. A more than 40% pressure drop for 19.5 min provided a 0.65 negative predictive value for high uNGAL, and a more than 50% pressure drop for 5.4 min provided a 0.67 negative predictive value. The link between uNGAL and oxygen delivery rate was negligible. CONCLUSION Maintaining the perfusion pressure above 60% of the normal age-standardised mean arterial pressure may provide an effective renal protective strategy. TRIAL REGISTRATION Registered on October 11, 2010, ClinicalTrials.gov Identifier: NCT01219998. Correspondence to Mirela Bojan, MD, PhD, Department of Anaesthesiology and Critical Care, Necker-Enfants Malades University Hospital, Assistance Publique – Hôpitaux de Paris, 149, rue de Sèvres, 75743 Paris, France Tel: +33 171396663; e-mail: mirela.bojan@nck.aphp.fr © 2018 European Society of Anaesthesiology

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10-10 Electrode Placement System

In a good overview of electrode nomenclature, Seeck et al. (2017) describe the methods for naming recording regions between the major 10-20 electrode nomenclature locations. This excellent presentation describes and illustrates current ideas about high density sampling sites.

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To warn or not to warn: A reappraisal of brainstem auditory evoked potential warning criteria during surgery

Neurophysiologic intraoperative monitoring (NIOM) is widely used to reduce neurologic morbidity in many types of surgeries where nervous tissue is at risk. Somatosensory and motor evoked potentials (SEP, MEP) have been shown to reduce the risk of paraplegia in spinal surgeries (Nuwer et al., 2012). Brainstem auditory evoked potentials (BAEP), similarly, have been shown to reduce the risk of hearing loss in surgeries involving the manipulation of the vestibulocochlear nerve, brainstem or cerebellum (Radtke et al., 1989).

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On the origin of epileptic High Frequency Oscillations observed on clinical electrodes

In drug-resistant partial epilepsies, resective surgery is the treatment of choice to suppress seizures, provided that the epileptogenic zone (EZ) is clearly identified and that it can be safely removed. In this context, the capacity to rely on objective biomarkers of the EZ is fundamental to define the optimal surgical approach in the specific context of each patient. Prior to surgery, patients may benefit from pre-surgical investigations, among which depth-EEG recordings which play a key role as the use of intracranial electrodes offer the unique opportunity to directly and locally record field potentials from brain areas with an excellent temporal resolution (sub-millisecond).

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On the origin of epileptic High Frequency Oscillations observed on clinical electrodes

Publication date: Available online 11 February 2018
Source:Clinical Neurophysiology
Author(s): Mohamad Shamas, Pascal Benquet, Isabelle Merlet, Mohamad Khalil, Wassim El Falou, Anca NICA, Fabrice Wendling
ObjectiveIn this study we aim to identify the key (patho)physiological mechanisms and biophysical factors which impact the observability and spectral features of High Frequency Oscillations (HFOs).MethodsIn order to accurately replicate HFOs we developed virtual-brain / virtual-electrode simulation environment combining novel neurophysiological models of neuronal populations with biophysical models for the source/sensor relationship. Both (patho)physiological mechanisms (synaptic transmission, depolarizing GABAA effect, hyperexcitability) and physical factors (geometry of extended cortical sources, size and position of electrodes) were taken into account. Simulated HFOs were compared to real HFOs extracted from intracerebral recordings of 2 patients.ResultsOur results revealed that HFO pathological activity is being generated by feed-forward activation of cortical interneurons that produce fast depolarizing GABAergic post-synaptic potentials (PSPs) onto pyramidal cells. Out of phase patterns of depolarizing GABAergic PSPs explained the shape, entropy and spatiotemporal features of real human HFOs.ConclusionsThe terminology "high-frequency oscillation" (HFO) might be misleading as the fast ripple component (200-600Hz) is more likely a "high-frequency activity" (HFA), the origin of which is independent from any oscillatory process.SignificanceNew insights regarding the origins and observability of HFOs along depth-EEG electrodes were gained in terms of spatial extent and 3D geometry of neuronal sources.



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