Understanding the Physiological Connection: Cardiac Arrest Following Prone Positioning.

Prone positioning of patients is a routine occurrence in procedural suites and operating rooms (ORs). However, the physiological changes that occur with prone positioning are frequently underappreciated by proceduralists, surgeons, and anesthesiologists. This may be related to a sense of the routine or a lack of familiarity with physiological changes that accompany the prone position. The prone position, while aiding visualization and cannulation of the ampulla of Vater during endoscopic retrograde cholangiopancreatography (ERCP), can induce physiological changes such as reduced preload, inferior vena cava filling, and cardiac output; it can also increase intrathoracic pressure and mediastinal compression. Anesthetic agents can further impact cardiopulmonary physiology, decreasing systemic vascular resistance and reducing cardiac contractility. In addition, the transition from negative to positive pressure ventilation following endotracheal intubation can increase pulmonary artery pressures and right ventricular (RV) strain. Therefore, caution is needed with patients who have RV dysfunction, pulmonary hypertension, or preload dependency, as they may not tolerate prone positioning. We describe a case in which a 73-year-old male patient scheduled for an ERCP suffered cardiac arrest after being transitioned to the prone position. The patient was repositioned in the supine position and resuscitated. The case was completed in the supine position.

Prediction of preoperative anxiety in children: who is most accurate?

BACKGROUND: In this investigation, we sought to assess the ability of pediatric attending anesthesiologists, resident anesthesiologists, and mothers to predict anxiety during induction of anesthesia in 2 to 16-yr-old children (n = 125). METHODS: Anesthesiologists and mothers provided predictions using a visual analog scale and children's anxiety was assessed using a valid behavior observation tool the Modified Yale Preoperative Anxiety Scale. All mothers were present during anesthetic induction and no child received sedative premedication. Correlational analyses were conducted. RESULTS: A total of 125 children aged 2-16 yr, their mothers, and their attending pediatric anesthesiologists and resident anesthesiologists were studied. Correlational analyses revealed significant associations between attending predictions and child anxiety at induction (r(s) = 0.38, P < 0.001). Resident anesthesiologist and mother predictions were not significantly related to children's anxiety during induction (r(s) = 0.01 and 0.001, respectively). In terms of accuracy of prediction, 47.2% of predictions made by attending anesthesiologists were within one standard deviation of the observed anxiety exhibited by the child, and 70.4% of predictions were within two standard deviations. CONCLUSIONS: We conclude that attending anesthesiologists who practice in pediatric settings are better than mothers in predicting the anxiety of children during induction of anesthesia. Although this finding has significant clinical implications, it is unclear if it can be extended to attending anesthesiologists whose practice is not mostly pediatric anesthesia.

High-frequency oscillatory ventilatory support during CT-guided percutaneous cryotherapy of renal masses.

PURPOSE: Computed tomography (CT)-guided percutaneous procedures are often made more difficult due to the movement of the kidney during respiration. Here we examine the use of high-frequency oscillatory ventilation (HFOV), which eliminates the movement of the kidney, potentially making cryoprobe access to the kidney simpler and possibly more efficient. METHODS: We compared seven CT-guided percutaneous procedures using a single cryoprobe and either standard mechanical ventilation (MV) (n=4) or HFOV (n=3). The variables studied included: total time of patient intubation, operative time, overall duration of interventional radiology (IR) suite time, change in hematocrit, narcotic use, and complications. The ease of the procedure was rated on a subjective scale from 1 to 3. RESULTS: The total intubation time remained nearly identical at 210 minutes for HFOV and 208 minutes for MV, but surgeon procedural time decreased by 31 minutes in the HFOV group (HFOV=99 minutes and MV=130 minutes) (P=0.40). Total IR time was 225 minutes for HFOV compared to 212 minutes for the MV group (P=0.63). There were no significant differences in the postoperative hematocrit, creatinine, or narcotic use between the two groups. There were no complications related to the procedure or anesthesia in either group. Both urology attending physicians and the interventional radiologist noted that the procedure seemed easier with HFOV. CONCLUSION: HFOV may shorten the actual procedural time required to perform cryoablation, likely due to the elimination of renal movement during the procedure, thereby facilitating targeting and access to the renal mass. In this initial experience, patients tolerated HFOV without incident, and the operating surgeons found it easier to perform the procedures.