This Month in Anesthesiology
Extraneural versus Intraneural Stimulation Thresholds during Ultrasound-guided Supraclavicular Block 1235
Figure. No caption a...Image Tools
There is no consistent stimulation threshold level which reliably indicates intraneural placement of the needle to avoid nerve injury and deliver adequate current to provoke a motor response. The authors evaluated the minimally required current to elicit a motor response, outside and inside the most superficial part of the brachial plexus during high-resolution, ultrasound-guided, supraclavicular block. The median stimulation threshold detected in 39 patients was significantly higher outside compared with inside the plexus (0.60 ± 0.37 mA vs
. 0.30 ± 0.19 mA), and stimulation currents ≤ 0.2 mA were not observed outside the trunk in any patient. These findings suggest that a minimum stimulation current of ≤ 0.2 mA is reliable to detect intraneural placement of the needle; furthermore, stimulation currents between 0.2 mA and 0.5 mA could not rule out intraneural position.
Preoperative Electrocardiograms: Patient Factors Predictive of Abnormalities 1217
To determine whether it is possible to target electrocardiogram ordering to patients most likely to have an abnormality that would affect management, and if age alone is predictive of significant electrocardiogram abnormalities, 1,149 electrocardiograms, including 89 patients with at least one significant abnormality were reviewed. Patients older than 65 yr, or who had a history of heart failure, high cholesterol, angina, myocardial infarction, or severe valvular disease were at higher risk of having a significantly abnormal electrocardiogram that would potentially affect management. These specific clinical risk factors were found to have a high sensitivity (87.6%) and identified all but 0.44% of patients with electrocardiogram abnormalities that may affect preoperative management. See the accompanying Editorial View on page 1205.
Morphine-6β-glucuronide Rapidly Increases Pain Sensitivity Independently of Opioid Receptor Activity in Mice and Humans 1356
Morphine-6β-glucuronide (M6G), a morphine metabolite with analgesic properties, can paradoxically increase pain sensitivity. The authors evaluated mice and humans for M6G hyperalgesia and assessed the contribution of N-methyl-d-aspartate receptor activity in mice. M6G injection (10 mg/kg) evoked analgesia in control mice; however, it caused hyperalgesia in mice treated concurrently with naltrexone and in mice lacking μ-, κ-, and Δ-opioid receptors. Continuous M6G infusion produced hyperalgesia within 24 h lasting a minimum of 6 days, in both placebo- and naltrexone-pelleted mice. Hyperalgesia was blocked and reversed by MK-801, the N-methyl-d-aspartate receptor antagonist, after the acute injection and continuous infusion of M6G, respectively. In humans, M6G increased heat pain sensitivity for at least 6 h independently of simultaneous naloxone infusion. M6G causes hyperalgesia independent of prior or concurrent opioid receptor activity or analgesia and a causal role for the N-methyl-d-aspartate receptor in mice is indicated. See the accompanying Editorial View on page 1209.
Anesthetic-induced Improvement of the Inflammatory Response to One-lung Ventilation 1316
The effect of one-lung ventilation on the pulmonary inflammatory response and the possible immunomodulatory effects of propofol and sevoflurane were prospectively investigated in 54 patients undergoing thoracic surgery. In patients prospectively randomized to receive sevoflurane, the increase of inflammatory mediators was significantly less pronounced and the number of composite adverse effects was significantly lower. Additionally, a positive correlation between neutrophils and mediators was demonstrated only in the propofol group. Sevoflurane anesthesia may have an immunomodulatory role and provide a significantly better clinical outcome in patients undergoing one-lung ventilation for thoracic surgery.
Hypoxemia during One-lung Ventilation: Prediction, Prevention, and Treatment (Review Article) 1402
Strategies to prevent and treat hypoxemia during one-lung ventilation are reviewed.
Feasibility of Tobacco Interventions in Anesthesiology Practices: A Pilot Study 1223
A simple tobacco intervention delivered by anesthesia providers was feasible and well-accepted. See the accompanying Editorial View on page 1207.
Approach Combining the Airway Scope and the Bougie for Minimizing Movement of the Cervical Spine during Endotracheal Intubation 1335
Combined use of the bougie and the Airway Scope reduced cervical spine movement compared with the Airway Scope alone.
Drowning: Update 2009 (Review Article) 1390
The epidemiology and pathophysiology of drowning and its treatment are reviewed. See the accompanying Editorial View on page 1211.
© 2009 American Society of Anesthesiologists, Inc.