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Background: Although the Modified Observer's Assessment of Alertness and Sedation (MOAA/S) is frequently used in sedation-related drug and device studies, a major shortcoming is that it does not differentiate between lighter and deeper levels of general anaesthesia because the only noxious stimulus of the MOAA/S is a trapezius squeeze. The primary aim of this investigation was to expand the MOAA/S score to include truly noxious stimulation, thereby extending the dynamic range of the assessment to include sedation states consistent with deeper levels of general anaesthesia., Methods: Twenty healthy volunteers received target controlled infusions of fentanyl (target=0.8 ng ml(-1)) and propofol (starting at 0.5 µg ml(-1) and gradually increasing to 5 µg ml(-1)). At each propofol concentration, a MOAA/S score was obtained before and after tetanic electrical stimulation. The tetanic electrical stimulation current was gradually increased until the subject responded or until 50 mA was delivered without a response. A pharmacodynamic model was constructed to characterize the concentration-effect relationship between propofol and the MOAA/S scores., Results: All subjects required a significantly higher propofol concentration to produce unresponsiveness to tetanic electrical stimulation at 50 mA compared with a standardized trapezius squeeze. The pharmacodynamic model adequately characterized the concentration-effect relationship., Conclusions: The Extended Observer's Assessment of Alertness and Sedation (or EOAA/S) extends the range of the widely used MOAA/S score to include truly noxious stimulation, thereby enabling the identification of drug-induced central nervous system depression representative of surgical anaesthesia., (© The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Although remifentanil's short-acting pharmacokinetic profile makes it well suited for procedures during which a brief period of intense analgesia is required, setting up an infusion pump for brief procedures is inconvenient. The clinical pharmacology of remifentanil administered by bolus injection, a more convenient alternative, has not been explored in detail. The primary aim of this study was to examine the safety of single bolus doses of remifentanil in conscious, healthy, adult volunteers breathing room air. Secondary aims included the evaluation of remifentanil pharmacokinetics and analgesic effects after bolus injection and a comparison of these issues in younger vs older adults., Methods: Using a randomized, double-blind, placebo-controlled, dose-escalation, crossover study design, 64 subjects (16 over 60 years old) received remifentanil or placebo by bolus injection in a fixed unit dose separated by a 1 h washout period. Respiratory effects were assessed using a respiratory intervention scale. Analgesic effects were assessed using pressure algometry. A population pharmacokinetic model was constructed using non-linear, mixed-effects modelling techniques based on arterial blood samples. Computer simulations were performed to illustrate the clinical application of the pharmacokinetic model., Results: Dose-related increases in both respiratory and analgesic effects were observed. In general, the respiratory depression observed was mild and easily treated with requests to breathe or the administration of oxygen, although the older cohort (and some younger subjects) experienced more substantial respiratory depression at lower doses. The pharmacokinetics of bolus-dose remifentanil were adequately described by a two-compartment model. The pharmacokinetic simulations illustrated the potential utility of bolus-dose remifentanil., Conclusions: Bolus injection could potentially be a safe and effective means of administering remifentanil in clinical situations requiring a brief period of intense analgesia. Because some subjects, both old and young, experienced significant respiratory depression even at low doses, careful monitoring of respiratory function is essential.

We report a case of awake, fiberoptic tracheal intubation of a difficult airway (Ludwig's angina) using remifentanil as part of the sedation-analgesia regimen. Remifentanil's rapid onset-rapid offset pharmacokinetic profile enabled precise control of the level of opioid effect. In combination with other drugs, remifentanil may offer some clinical advantages compared to the other fentanyl congeners in providing the opioid component of conscious sedation-analgesia for awake tracheal intubation in patients with difficult airways.

We report a case in which morphine in combination with intravenous diazepam delivered via patient-controlled analgesia resulted in complete apnea and carbon dioxide narcosis in a patient admitted for cervical traction. A patent airway and high flow oxygen face mask maintained oxygenation despite complete apnea, thus rendering the pulse oximeter useless in detecting the respiratory depression. The case illustrates the limitations of pulse oximetry in detecting opioid induced respiratory depression when the conditions necessary for apneic oxygenation are present.

We present a case in which remifentanil infusion was used to provide analgesia during epidural catheter placement in a parturient who was experiencing great difficulty staying motionless because of extremely painful uterine contractions. Remifentanil may provide certain advantages in this setting, including improved analgesia during the procedure, briefer residual maternal and fetal (or newborn) drug effects after the procedure, and greater technical ease of catheter placement because of decreased movement induced by pain. Pharmacokinetic simulation of the dose administered suggests that analgesic effect-site concentrations can be rapidly produced, and that these concentrations decline rapidly to clinically insignificant levels after the infusion.

Perioperative smoking causes acute changes in cardiopulmonary function that can have unfavorable implications for patients undergoing anesthesia. These cardiopulmonary effects are carbon monoxide and nicotine mediated changes in oxygen (O2) delivery and myocardial O2 balance. Smokers also are at increased risk for postoperative pulmonary complications that are secondary to chronic changes in lung function. Smoking-induced acute changes in cardiopulmonary function can be largely avoided by a brief period of preoperative smoking abstinence. Bringing about a decrease in postoperative pulmonary complications requires a much longer period of preoperative abstinence. Because the perioperative period is in many ways an ideal time to abandon the smoking habit permanently, anesthesiologists, in cooperation with other health professionals, can perhaps play a more active role in facilitating this process.

An athletic young male presented with right calf pain following a twisting injury during a soccer game. Other than apparently severe calf pain, no symptoms or signs of compartment syndrome were noted. The patient later returned with lateral and anterior compartment syndrome, and suffered partial loss of peroneal nerve and muscle function despite fasciotomy. Although rare, acute compartment syndrome resulting from seemingly minor injury or exertion has been reported. Pain out of proportion to the apparent injury and a history of chronic leg pain with exertion may be helpful in identifying these patients prior to development of more obvious signs and symptoms. The diagnosis of acute compartment syndrome may be confirmed by compartmental pressure measurement. Prompt intervention is indicated once the diagnosis is established.