David G. Bjoraker

Maximum blood savings by acute normovolemic hemodilution.

Acute normovolemic hemodilution (ANH) entails collecting blood from a patient immediately prior to surgery with concurrent fluid infusion to maintain intravascular volume constant.Blood collected during ANH is later reinfused to replace the red cell losses that occur during surgery. This technique is advocated as a means to reduce or eliminate homologous blood transfusion during surgery. Published guidelines for performing ANH vary, and the literature does not describe how to perform ANH to achieve the maximum benefit for a given patient. To evaluate how to save red blood cells as much as possible via ANH, and to determine the maximum benefit that can be expected, we developed a mathematic model of the process. Using the model, the net red cell mass savings possible when using ANH can be calculated given the patients weight, initial hematocrit and minimum safe hematocrit. Results are reported to demonstrate the impact of the initial hematocrit and minimum safe hematocrit on the red cell savings possible with ANH. The data indicate that ANH does indeed save red blood cells that would otherwise be lost during surgery. However, the red cell savings possible when using ANH are not as much as typically published and, a degree of hemodilution more than that which is typically recommended is necessary to achieve even modest red cell savings. (Anesth Analg 1995;80:108-13)

Portable devices used to detect endotracheal intubation during emergency situations : A review

OBJECTIVES To review the operational characteristics of commercial devices used to detect endotracheal intubation; and to identify an ideal device for detecting endotracheal intubation in emergency situations, especially in the prehospital setting during cardiac arrest. DATA SOURCES Relevant articles from the medical literature are referenced. STUDY SELECTION The authors identified the need for understanding the basic operation principles of portable devices used to detect endotracheal intubation and to correctly use them in unpredictable clinical situations. DATA EXTRACTION Data from published literature. DATA SYNTHESIS Recently, a number of new portable devices have been marketed for detecting endotracheal intubation, each having advantages and disadvantages, especially when used during emergency situations. The devices are classified based on their principle of operation. Some rely on CO2 detection (STATCAP, Easy Cap, and Pedi-Cap), others utilize the transmission of light (Trachlight, SURCH-LITE), one operates based on reflection of sound energy (SCOTI), and some depend on aspiration of air (TubeChek and TubeChek-B). A brief description of each device and its operational characteristics are reviewed. A comparative analysis among the devices is made based on size, portability, cost, ease of operation, need for calibration or regular maintenance, reliability for patients with and without cardiac arrest, and the possibility of use for adult and pediatric patients. False-negative and false-positive results for each device are also discussed. False-negative results mean that although the endotracheal tube is in the trachea, the device indicates it is not. False-positive results mean that although the endotracheal tube is in the esophagus, the device indicates it is in the trachea. CONCLUSIONS Although no clinical comparative study of commercial devices to detect endotracheal intubation exists, the syringe device (TubeChek) has most of the characteristics necessary for a device to be considered ideal in emergency situations in the prehospital setting. It is simple, inexpensive, easy to handle and operate, disposable, does not require maintenance, gives reliable results for patients with and without cardiac arrest, and can be used for almost all age groups. The device may yield false-negative results, most commonly in the presence of copious secretions and in cases of accidental endobronchial intubation. Regardless of the device used, clinical judgment and direct visualization of the endotracheal tube in the trachea are required to unequivocally confirm proper endotracheal tube placement.

Incidence of choledochoduodenal sphincter spasm during fentanyl-supplemented anesthesia.

One hundred patients were studied prospectively to assess the incidence of spasm of the choledochoduodenal sphincter during biliary tract surgery performed under a fentanyl-supplemented anesthetic technique. The incidence of failure of passage of contrast medium into the duodenum was 3%. In each of the three patients with cholangiographic evidence of sphincter spasm, contrast medium flowed freely into the duodenum after the intravenous administration of 2 mg of glucagon. It is concluded that spasm of the choledochoduodenal sphincter is an uncommon occurrence during fentanyl-supplemented anesthesia and that this method of anesthesia is suitable for biliary tract surgery.

Catheter thrombus artifactually decreases thermodilution cardiac output measurements.

Flow-directed pulmonary artery catheters, which are used routinely in the measurement of cardiac output by thermodilution, are thrombogenic (1-3). Heparincoated pulmonary artery catheters, which are now available for clinical use from several manufacturers, have been shown to be efficacious in preventing catheter thrombus in humans (2,3). The decision to use heparin-coated catheters may be aided by determining the effect of thrombus around the catheter thermistor on the accuracy of thermodilution cardiac output determinations. Precise stable flow and exact knowledge of thrombus size at the catheter thermistor are difficult to achieve in vivo. Therefore, an in vitro study was conducted to assess the effect of human thrombus on thermodilution cardiac output measurements. TWO sizes of thrombus, three flows, and two types of computers and catheters were studied.

Asystole during temporomandibular joint arthrotomy

MOST anesthesiologists are aware that compression of the eye or traction on the extraocular muscles can cause oculocardiac reflex. Perhaps less well known is that noxious stimulation of trigeminal divisions other than the ophthalmic division (V 1 ) can also trigger life-threatening dysrhythmia and asystole. We present a case of asystole after stimulation of the mandibular division of the trigeminal nerve (V 3 ).