Key points It is unknown whether excessive reactive oxygen species (ROS) production drives the isocapnic hyperoxia (IH)‐induced decline in human cerebral blood flow (CBF) via reduced nitric oxide (NO) bioavailability and leads to disruption of the blood–brain barrier (BBB) or neural‐parenchymal damage. Cerebral metabolic rate for oxygen (CMRnormalO2) and transcerebral exchanges of NO end‐products, oxidants, antioxidants and neural‐parenchymal damage markers were simultaneously quantified under IH with intravenous saline and ascorbic acid infusion. CBF and CMR normalO2 were reduced during IH, responses that were followed by increased oxidative stress and reduced NO bioavailability when saline was infused. No indication of neural‐parenchymal damage or disruption of the BBB was observed during IH. Antioxidant defences were increased during ascorbic acid infusion, while CBF, CMR normalO2, oxidant and NO bioavailability markers remained unchanged. ROS play a role in the regulation of CBF and metabolism during IH without evidence of BBB disruption or neural‐parenchymal damage. Abstract To test the hypothesis that isocapnic hyperoxia (IH) affects cerebral blood flow (CBF) and metabolism through exaggerated reactive oxygen species (ROS) production, reduced nitric oxide (NO) bioavailability, disturbances in the blood–brain barrier (BBB) and neural‐parenchymal homeostasis, 10 men (24 ± 1 years) were exposed to a 10 min IH trial (100% O2) while receiving intravenous saline and ascorbic acid (AA, 3 g) infusion. Internal carotid artery blood flow (ICABF), vertebral artery blood flow (VABF) and total CBF (tCBF, Doppler ultrasound) were determined. Arterial and right internal jugular venous blood was sampled to quantify the cerebral metabolic rate of oxygen (CMRnormalO2), transcerebral exchanges (TCE) of NO end‐products (plasma nitrite), antioxidants (AA and AA plus dehydroascorbic acid (AA+DA)) and oxidant biomarkers (thiobarbituric acid‐reactive substances (TBARS) and 8‐isoprostane), and an index of BBB disruption and neuronal‐parenchymal damage (neuron‐specific enolase; NSE). IH reduced ICABF, tCBF and CMR normalO2, while VABF remained unchanged. Arterial 8‐isoprostane and nitrite TCE increased, indicating that CBF decline was related to ROS production and reduced NO bioavailability. AA, AA+DA and NSE TCE did not change during IH. AA infusion did not change the resting haemodynamic and metabolic parameters but raised antioxidant defences, as indicated by increased AA/AA+DA concentrations. Negative AA+DA TCE, unchanged nitrite, reductions in arterial and venous 8‐isoprostane, and TBARS TCE indicated that AA infusion effectively inhibited ROS production and preserved NO bioavailability. Similarly, AA infusion prevented IH‐induced decline in regional and total CBF and re‐established CMR normalO2. These findings indicate that ROS play a role in CBF regulation and metabolism during IH without evidence of BBB disruption or neural‐parenchymal damage.

The incidence of meningitis was similar in patients subjected to spinal anesthesia and in those subjected to other anesthetic techniques. Asepsis techniques were found to differ considerably among our staff members, reflecting the lack of well-defined published standards for this procedure. We recommend that asepsis for spinal anesthesia should not be less rigorous than for surgical asepsis.

Peripheral venous distension mechanically stimulates type III/IV sensory fibers in veins and evokes pressor and sympathoexcitatory reflex responses in humans. As young females have reduced venous compliance, smaller increases in arterial pressure to type III/IV sensory fibers activation and impaired sympathetic transduction, we tested the hypothesis that pressor and sympathoexcitatory responses to venous distension may be attenuated in women compared to men. Mean arterial pressure (MAP, photoplethysmography), heart rate (HR), stroke volume (SV, Modelflow), cardiac output (CO = HR x SV), muscle sympathetic nerve activity (MSNA), femoral artery blood flow and conductance (FABF and FACT, Doppler ultrasound) were quantified in 8 males (27 ± 4 yrs.) and 9 females (28 ± 4 yrs.) before (CON) during (INF) and after (Post‐INF) a local infusion of normal saline (5% of the forearm volume) through a retrograde catheter inserted into an antecubital vein of the forearm, to which venous drainage and arterial supply had been occluded. MAP increased during and after infusion in both groups (vs. CON, p ≤ 0.05) but women showed a smaller pressor response in the Post‐INF period (Δ+7.2 ± 2.0 vs. men Δ+18.3 ± 3.9 mmHg, p = 0.019). MSNA increased and FACT decreased similarly in both groups (vs. CON, p ≤ 0.05) at Post‐INF. While HR changes were similar, increases in SV (Δ+20.4 ± 8.6 vs. Δ+2.6 ± 2.7 mL, p = 0.05) and CO (Δ+0.84 ± 0.17 vs. Δ+0.34 ± 0.10 L/min, p = 0.024) were greater in men than women. Therefore, these findings indicate that venous distension evokes a smaller pressor response in young women due to attenuated cardiac adjustments rather than to reduced venous compliance or sympathetic transduction. Support or Funding Information Support: CNPq, CAPES, FAPERJ This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

I nadequate antagonism of neuromuscular blocking drugs (NMBDs) may lead to a residual neuromuscular block that is associated with morbidity and death. One issue is why a wide gap still exists between the experts' recommendations and current clinical practice regarding monitoring and antagonism of NMBDs. This study aimed to describe the rules of thumb (heuristics) and biases associated with clinical intuition regarding neuromuscular block assessment.Sequential surveys were conducted with 108 clinical anesthesiologists to determine the rules of thumb that support their decisions and provide a measurement of the confidence the clinicians have in their own decisions compared with decisions made by their peers. After an initial questionnaire was sent to 15 randomly chosen clinicians and returned, a final questionnaire was created containing 4 questions with 5 choices in each, formulated to describe clinicians' beliefs not addressed in answers to the routine scenario in the initial questionnaire. Two questions were presented to elicit the clinician's perception of the prevalence of clinically important residual block, defined as the inability to maintain a 10-second head lift after tracheal extubation.The mean age of the clinicians was 45 T 11 years, with 18 T 10 years of experience. The 2 most frequently chosen heuristics were Bthe interval since the last NMBD dose was short and the breathing pattern is inadequate,[ which was chosen by 73% and 71% of the respondents, respectively. The most frequently important heuristics were time since last NMBD dose, breathing pattern, muscular strength, type of NMBD, ventilometry results, total NMBD dose, train-of-4 (TOF) value (quantitative), head lift maintenance, and TOF fade (qualitative). Clinicians indicated that a prevalence of clinically important residual block of 5% or higher was less frequent in their own practice than in the colleagues' practices (16% vs 60%), meaning that they consider their colleagues' practices to be associated with a higher probability of residual paralysis than they do their own practice. They perceived the duration of action of atracurium as shorter than that of rocuronium. Antagonism was reported as unnecessary when more than 60 minutes elapsed since a single dose of atracurium by 69% of respondents compared with 47% after rocuronium.Clinicians are overconfident in their intuition to evaluate and avoid residual block. Their decisions were based on putative pharmacology and qualitative judgment about the adequacy of breathing pattern. With awareness of these errors related to clinical intuition, recommendations from experts may be adopted more readily.

In our institution, the clinical decision to antagonize NMBD is mainly based on the pharmacological forecast and a qualitative judgment of the adequacy of the breathing pattern. Clinicians judge themselves as better skilled at avoiding residual block than they do their colleagues, making them overconfident in their capacity to estimate the duration of action of intermediate-acting NMBD. Awareness of these systematic errors related to clinical intuition may facilitate the adoption of experts' recommendations into clinical practice.

Although preoxygenation has been extensively studied, to our knowledge this is the first study addressing its optimal length in children, who form a high risk group for developing hypoxaemia during induction of anaesthesia. Recommended preoxygenation times in children range between 1 and 4 min, but whether one of these times maintains arterial oxygen saturation (Sao2) at an adequate level for a longer time period is unknown. This study was performed on 11 healthy children, randomly distributed into either Group 1 (1 min of preoxygenation, n = 6) or Group 2 (3 min of preoxygenation, n = 5). Sao2 was measured by pulse oximetry. While the patients were breathing room air, Sao2 was similar in both groups (97%) and rose to 100% after preoxygenation in all patients. After intravenous induction of anaesthesia and muscle relaxation, all patients became apnoeic. The time taken for the Sao2 to decrease to 90% was measured. In Group 1 this occurred in 91 s, whereas Group 2 required 144 s. Thus, a 3-min rather than a 1-min period of preoxygenation would appear to maintain Sao2 at a safe level for a longer time in children.

The interesting article by Flaishon et al. 1 included prospective data on the difficulties of performing anesthetic and critical care duties in mass casualty situations. An additional factor to consider is the challenge of continuing to perform one's duties while wearing full antichemical protective gear.As a member of the Air National Guard, I am obligated to perform chemical warfare training. Wearing the full MOPP 4 antichemical warfare ensemble is uncomfortable, especially in warm environments such as the Middle East. The clinician must contend with the intrinsic difficulties of wearing the suit and be mindful of preventing his own severe dehydration and the need to be resuscitated himself.Most United States civilians do not appreciate the need to maintain adequate hydration. In the Middle East, constant hydration is a way of life. Military personnel have become familiar with disaster management concepts. In the future, such training will be mandatory for civilians as well. The Society of Critical Care Medicine (Des Plaines, IL) sponsored its first course on disaster medicine at its annual meeting this year to provide civilian clinicians with the basic concepts of disaster management. The course will heighten awareness of the challenges of airway management as well as the challenges and hazards of extended wear of chemical warfare gear.

Remifentanil is currently the best opioid for continuous intravenous infusion and may improve anesthesiologist's efficiency provided usage recommendations are followed.