Effect of ventilation with soluble and diffusible gases on the size of air emboli

Choice of anesthetics

The choice of anesthetics for vascular surgical patients is not only determined by the kind and extent of the surgical procedure but also by patient comorbidities. Frequently, patients have a history of hypertension, peripheral vascular and coronary artery disease,cerebrovascular disease, and renal impairment. The goal of the chosen anesthetic technique is to protect organ function, mainly of the brain and the heart. In some instances regional anesthesia might be preferred, but no difference in outcome between the two techniques has been shown conclusively. Vascular emergencies are particularly challenging for the anesthesiologist, but in recent years the development of stent graft insertion has improved the short-term outcome in many of these procedures.

Cardiac arrest during surgery and ventilation in the prone position: a case report and systematic review

We present a case report of successful resuscitation following cardiac arrest in a patient undergoing surgery in the prone position. A systematic review of the literature identified 22 further cases. Risk factors for intra-operative cardiac arrest in patients in the prone position include: cardiac abnormalities in patients undergoing major spinal surgery, hypovolaemia, air embolism, wound irrigation with hydrogen peroxide, poor positioning and occluded venous return. Cardiac arrest is also a risk in the increasing number of patients with acute respiratory distress syndrome ventilated in the prone position. Management of prone cardiac arrest may be improved by identification of high-risk patients, careful patient positioning, use of invasive monitoring and placement of self-adhesive defibrillator paddles. Suitable techniques for cardiopulmonary resuscitation including methods for chest compression, defibrillation and the management of air embolism are discussed.

Spatial distribution of venous gas emboli in the lungs

The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-microm fluorescent microspheres at baseline and during N(2) embolism. The animals were killed, and the lungs were excised, air-dried, and diced into approximately 2-cm(3) pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 +/- 1% per additional centimeter in height compared with baseline (P = 0.0003). Embolism also increased radially by 3 +/- 1%/cm from the hilum (P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 +/- 2% for every 1. 0 increase in relative baseline flow (P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature.

Anesthetic problems. Venous air embolism, airway difficulties, and massive transfusion

Perioperative anesthetic complications require the coordinated efforts of both the surgical and anesthesia teams. These complications, or their sequelae, have significant influence on the care of the patient in the preoperative, intraoperative, and postoperative periods.