This Month In: Anesthesiology

Significant disruptions of blood coagulation can occur during cardiac arrest and cardiopulmonary resuscitation, predisposing patients to a procoagulant state and possible widespread vascular thromboses. Endogenous coagulation changes can be augmented by therapeutic interventions during cardiopulmonary resuscitation and by ischemic tissue reperfusion. Hypothermia inhibits the blood’s clotting ability and extracorporeal membrane oxygenation therapy leads initially to thromboses and subsequently to hyperfibrinolysis. Coagulopathies encountered commonly in cardiac arrest and during thrombolysis, hypothermia, and extracorporeal membrane oxygenation treatments are reviewed.

Establishing early vascular access during resuscitation of critically ill patients can have a substantial effect on outcome. However, dehydration and massive blood loss can cause peripheral veins to collapse and central line placement can be time consuming. The intraosseous space is a noncollapsible entry point into the systemic circulation that can be accessed quickly and accurately in an emergency situation with minimal disruption of cardiopulmonary resuscitation. The clinical use of intraosseous vascular access as well as its contraindications and complications are reviewed as are insertion sites and insertion devices.

From the Nationwide Inpatient Sample, a representative sample of annual hospital admissions in the United States, 4,843 cardiopulmonary arrests were identified among 56,900,512 hospitalizations for delivery between 1998 and 2011, an event rate of 8.5 per 100,000 hospitalizations for delivery. Although hemorrhagic conditions accounted for the largest fraction of maternal arrests, amniotic fluid embolism has the strongest cause-specific association. Fifty-nine percent of the women who suffered cardiac arrest survived to hospital discharge; survival was lowest for aortic dissection or rupture and trauma and highest for aspiration pneumonitis and medication-related complications. See the accompanying Editorial View on page 790.

Anesthetic preconditioning reduced myocardial infarct size in both Wistar and type 2 diabetic (T2DN) rats with mitochondrial DNA from Wistar rats but not in T2DN rats with mitochondrial DNA from Fawn Hooded Hypertensive (FHH) rats because of increased reactive oxygen species (ROS) production after ischemia–reperfusion in the latter rats. The ROS scavenger N-acetylcysteine (NAC) decreased infarct size in both strains of diabetic rats and restored anesthetic preconditioning in T2DN rats with FHH mitochondrial DNA. NAC abolished anesthetic preconditioning in normal Wistar rats because small quantities of ROS are required to induce cardioprotective signal transduction during anesthetic preconditioning.

Adequacy of general anesthesia has long been assessed using nonspecific physiological responses. More specific effects of general anesthetics on the brain are now being assessed using various monitors. An anesthesia multimodal index of consciousness (AMIC) was developed by integrating standard and electroencephalographic monitoring data collected from 263 adult patients undergoing general anesthesia by 1 of 10 anesthetic combinations. The prediction probability of the AMIC for different levels of anesthesia was better than that of either standard monitoring parameters or bispectral index monitoring alone, suggesting it may more precisely reflect the level of anesthesia. See the accompanying Editorial View on page 799.

Combined psoas compartment–sciatic nerve block (CPCSNB) can be used to provide surgical analgesia during operative hip fracture repair. Although CPCSNB has advantages over neuraxial analgesia, it is not without risks. The case of an elderly woman presenting for operative repair under CPCSNB is discussed; she not only experienced delayed signs and symptoms of local anesthetic systemic toxicity (LAST) but also had patient-specific factors confounding the diagnosis. Influences on decision making, effective emergency management principles, and the incidence, presentation, differential diagnosis, and treatment of LAST are reviewed.

To determine whether and to what extent under general anesthesia the brain continues to process and ultimately perceive sensory information, 107 rats were randomly assigned to 12 different anesthesia and odor exposure paradigms. Ketamine–xylazine anesthesia was used to avoid olfactory stimulation by pungent volatile anesthetics. The immediate early gene product c-Fos immunoreactivity distinguished novel from familiar odorant responses as did exploratory behavior. Reexposing animals to odorants experienced under anesthesia produced c-Fos immunoreactivity similar to that of familiar odorants but in the absence of behavioral recall, suggesting general anesthesia causes disintegration of information processing while preserving cellular communication.

Lung and cardiac ultrasound examinations performed before and after delivery in 20 parturients with severe preeclampsia were compared with antepartum examinations in 20 control parturients. Lung ultrasound detected interstitial edema in five parturients with severe preeclampsia. Ultrasound lung comets are echographic signs of extravascular lung water accumulation early in the course of lung injury. An echo comet score of more than 25 predicted an elevation of left ventricular end-diastolic pressure with a sensitivity of 1.00, a specificity of 0.82, a positive predictive value of 0.59, and a negative predictive value of 1.00.