Objectives

1. List the basic guidelines for monitoring of patients receiving anesthesia.

2. Evaluate options, functions, use, and problems associated with monitoring devices, particularly in the trauma setting.

3. Interpret the information provided by monitoring devices.

INTRODUCTION

In 1986, the American Society of Anesthesiologists (ASA) prepared and approved “Standards for Basic Anesthetic Monitoring” [1]. This document outlines the responsibilities of the anesthesiologists in assessing patients' vital signs throughout the anesthetic period. Similar guidelines have been published by the Australian and New Zealand College of Anaesthetists (ANZCA) and The Royal College of Anesthetists [2, 3]. Both the Royal College and the ASA note that, in extreme circumstances, provision of life-saving measures takes precedence over application of monitors. Nonetheless, monitoring is intended to improve the quality of care and outcome for patients, and every attempt should be made to appropriately monitor the trauma patient.

All anesthesia providers have an obligation to carefully assess their patients receiving any form of anesthetic. Basic principles include monitoring the physiologic variables of oxygenation, ventilation, circulation, and temperature. Oxygenation can be assessed with pulse oximetry, inhaled and exhaled gas analysis, and blood gas analysis. Ventilation is assured by end-tidal carbon dioxide measurement, listening to the patient's breath sounds, and monitoring the ventilator. Circulation is assessed by electrocardiogram and blood pressure measurements, whether noninvasively by a cuff or invasively by an intraarterial catheter. Circulation can also be monitored invasively through echocardiography and pulmonary artery catheter measurements. Urine output provides a rough estimate of tissue perfusion and thus is another monitor for circulation.