Volume 7, No. 4 • Winter 1992

ASA Exhibits Show Safety Suggestions

John H. Eichhorn, M.D.

Safety-related technology and ideas certainly were featured in the technical and scientific exhibits at the American Society of Anesthesiologists Annual Meeting in New Orleans in October, but there were comparatively few genuinely new ideas. Packaging and presentation of existing technology continues to vary in a multiplicity of permutations and combinations.

In the technical exhibits, patient temperature seemed to surpass oximetry as the most common focus. There were at least 12 major displays centering on the issue of unintended patient hypothermia in the operating room. Many varieties of the already existing mechanisms to add and/or preserve heat in an anesthetized patient (from above, below, or via the gases and fluids) were presented. In response to questioning on the reason for the emphasis on this topic, representatives from various companies with these displays replied that anesthesia practitioners seemed very concerned with their patients who accidentally become cold during surgery.

Various nontraditional monitors were highly touted. There was an esophageal probe that allows ECG recording from directly behind the heart (and another that can be used for cardiac pacing). The cerebral oximeter with an infrared sensor applied to the forehead that is claimed to read regional brain tissue oxygen saturation through the skull bone was displayed again. Advertised as a new technology, a noninvasive cardiac output monitor was shown. It involves two electrodes on the left lateral chest wall and also two at the root of the neck. A low amplitude current is generated and the electrical conductivity of the blood causes changes in intrathoracic incidence that can be detected by the monitor which then does ‘time-frequency signal processing’ to make projected calculations about the mechanical function of the heart. Among the many parameters displayed on the monitor are CO, stroke volume, ejection fraction, end-diastolic volume, and SVR.

A new smart technology for vessel finding was displayed. An ultrasound device that detected differences, for example, between the internal jugular vein and the carotid artery can be attached to a needle and apparently help guide needles and catheters into the central venous circulation.

Real-time blood gas measurement technologies were more numerous this year. Four that involve intra-arterial sensors and two that make measurements outside the body were displayed. AU these manufacturers stated with no hesitation that they have finally solved the fibrin-deposition problems that have prevented this type of technology from succeeding in the past.

Automated anesthesia record keeping devices and OR information management systems were prominent with three of each offering new upgrades of previously available technology.

In a simple, but important, area, there were several devices shown that are specifically intended to shield and protect anesthetized patients’ ulnar nerves from potential compression damage and resulting neuropathy.

New versions of labels for syringes that are intended to help avoid wrong-medication errors were prominently displayed.

A pneumatic device to allow ‘pumping up” for left uterine Wt to avoid aorto-caval compression was offered as a new easy way to implement this important safety maneuver.

While not specifically offered as new safety devices, laryngeal mask airways arrived in full force in the US at this meeting. How these impact practice and any safety implications, positive or negative, remains to be seen as they are put into clinical practice and studied.

In the scientific exhibits, there was a demonstration of a proposed simple way to detect esophageal intubation. A compressed large suction bulb is attached to the connector of a newly placed endotracheal tube. If the deflated bulb immediately reinflates, the tube is in the trachea. If not, it is either in the esophagus or obstructed. The presenter stated that this had been used in more than 1,500 anesthetics and it had correctly diagnosed one unrecognized esophageal intubation.

Bulb for Trachea

Potentially a harbinger of the future, another scientific exhibit featured a so-called ‘heads-up” display of monitoring information on a screen attached to the surgical drapes at the level of the patient’s head. This computer-based projection system allows the monitoring displays to be seen by the anesthetist in the same field of vision as the patient. Such technology may eventually lead to helmet or even eye-glass like devices (similar to those used by fighter pilots) the anesthetist will wear and then have all the monitoring displays always directly in view.

Dr. Eichhorn of the University of Mississippi is Editor of the APSF Newsletter.