of patients. It is impossible to practice ... today and tomorrow the way we practiced. 10 years ago. ... fluctuations in circulation mayoccur result- .... Precordial Stethoscope (Wenger Chest. Piece). This is ... trode into each bare axilla and transmits.
Anesthesia Monitoring of the
Ambulatory Patientt
Trieger, N., Erlichman, M., Barkin, M., Goldmith, D., Schiffman, L., Levin, D., Sturman,
Introduction Ten years ago, Greenfield' reviewed "Monitoring of the Ambulatory Patient Under General Anesthesia," in Anesthesia Progress. At that time only the exceptional dental office using general anesthesia employed a cardiac monitor. Today, the use of cardiac and other electronic monitoring devices is wvidespread. The crux of his discussion is as valid today as it was in 1966 w,hen he advised that electronic or mechanical aids are not meant to replace the clinical acumen of the anesthesiologist. Thev sen-e primarily to provide additional information about the status of the patient so that necessarv changes can be effected in the anesthetic management. One of the subtle changes that has occurred during the last decade was the ability to achieve continuous nmonitoring with the aid of electronic devices rather than intermittent recordings of vital signs. Continuous monitoring enables the anesthetist to avoid unwarranted surprises of sudden changes in the patient's status. WNTith ever better supervision of the anesthetized patient comes a more sophisticated understanding of some of the effects of anesthetics currentlv in use, as wvell as the pathophvsiological changes induced bv the stress of surgery superimposed on underlying systemic disease. Dentist-anesthesiologists are keeping up svith newer developments in anesthetic management. The favorable record of lowv morbidity and mortalitv achieved by oral surgeons, attest to their cautious pre-operati,-e assessment and successful anesthetic care. But, professional standards mandate that we continue to improve our treatment of patients. It is impossible to practice tFrom the Department of Dentistry & Oral Surgery, Montefiore Hospital & Medical Center, Bronx, NeN-- York. M\ A,Y-JU-NF 1976
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today and tomorrow the way we practiced 10 years ago. Professional societies as well as other regulatory groups are setting higher guidelines and requirements. The American Society of Oral Surgeons has recently approved compulsory peer review in the form of Office Self-Evaluation for emergency and anesthesia management. One of their basic tenets defines the need for continuous monitoring of the patient by members of the anesthetic team knowledgeably prepared and appropriately equipped. Because of these recent developments, this article reviews some principles and methods of monitoring ambulatory patients. The material presented is by no means comprehensive. It is based on a solicitation of information from equipment manufacturers. Although wve endeavored to include all monitoring equipment, it is obvious that the field is vast and only a portion of it applies to ambulatory anesthesia. Also, the authors did not receive the requested information from all companies and hence the report is incomplete. However, it offers considerable data wvith which to form an opinion as to the practitioner's needs based on his type of anesthetic management. Medical progress in the last few years has made it possible to continuouslv record electrocardiographic data and rapidly sift these data via computor analvsis. In voung normal subjects, continuous ambulatorv monitoring shows arrhythmias to be infrequent.' Premature ventricular contractions do occur in fewer than 10c of normal young patients. However, these data do not include recording during the stress of a dental appointment or ambulatory anesthesia. Others- have reported distinct ECG changes related to specific dental manipulations. These changes wvere transient a;nd a return to normal rhythm following removal of the stimulus. In general, the incidence of pre-operative and intraoperative I,9
arrhythmias increases with age and known cardiovascular disease. Patients with cardiovascular disease showed a 33% incidence of arrhythmias, with multifocal PVCs occurring in 10%.4 Tuohy5 found that 80% of patients with heart disease developed cardiac rhythm abnormalities. It has been shown that life-threatening arrhythmias are often preceded by less serious ventricular contractions, coupled PVCs and R on T premature ventricular contractions.2 Noble7 reported that the variety of cardiac irregularities seen in patients under general anesthesia were also found during local anesthesia. Driscoll6 showed an incidence of arrhythmias of 46% for patients undergoing extractions under local anesthesia. This incidence dropped to 30c when diazepam sedation was used. Similar reports point to the need for better monitoring in anticipation of adverse changes under anesthesia. In this report various monitoring approaches are presented: Blood pressure, respiratory monitoring, pulse and heart beat, and cardiac monitors. Blood Pressure Arterial pressure must be maintained at levels sufficient to permit adequate perfusion of the extensive capillary networks in the vascular bed. In generaL the patient's blood pressure should be maintained at its usual level, not at an arbitrary level such as 120/80. StilL due to oscillation of the pressor-receptors the blood pressure varies continually within 10 to 20 mm. of mercury, (Mayer waves or Traube-Hering waves). The oral surgery patient receives a variety of medications which alter his circulatory control. In addition, he may have an impaired circulatory system. Larger fluctuations in circulation may occur resulting in inadequate perfusion. Therefore, the patient's blood pressure requires frequent monitoring. A patient's blood pressure may be determined directly or indirectly. Obviously, on an out-patient basis the direct method is not practical. However, it is utilized occasionally during major oral, maxillo-facial surgical procedures which employ hypotensive anesthesia. A disposable system, BPMc/D (Blood Pressure Monitor Continuous and Disposable) called "Pressurveil" by the Concept Company in St. Petersburg, 80
Florida claims to have certain distinct advantages. It is a small self-contained disposable system. No electric power, warm-up time or calibration of the transducer is required. The TPressurveil1 is suggested as a simple way to monitor blood pressure continuously: It may be used to monitor central venous pressure, mean arterial, pulmonary mean or pulmonary wedge pressures. Indirect methods require little time expenditure, are readily obtainable on the out-patient, and are easily performed by auxiliary personnel. The standard means include the use of a sphygmomanometer which consists of an inflatable balloon within a culf of fabric which can be wrapped around the upper forearm. Air is pumped into the balloon by means of a rubber bulb and the air pressure that is generated is read either on an aneroid or mercury manometer. The pressure is released slowly to the point where blood flow returns into the brachial artery and the systolic sound is recorded. As the pressure continues to decrease, the varying Korotkoff sounds are heard. Diastolic pressure is usually indicated by a marked change in the intensity of sound with some pulsations continuing well beyond this point. A mercury manometer is usually more accurate than an aneroid, although it is more cumbersome. Errors may be introduced if the cuff is too loosely fitting or of inadequate size for the arm. While the stethescope diaphragm can be readily secured to the antecubital fossa for frequent monitoring, another modification of the stethoscope head is the Dyasyst (Fig. 1) which is made
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Figure 1
ANEsThEsiA PRoGRESs
of soft pliable rubber and contours to fit the patient's arm. The sound chamber, unlike that of the conventional stehtescope is elongated to allow some latitude and placement over the artery. It is fastened to the blood pressure cuff by means of velcro, thus elinminating the need for an encircling band or adhesive tape. Other aids in the indirect technique of measuring blood pressure include use of a two-way valve which can alternatively record blood pressure readings or heart sounds via a precordial stethescope. A simpler mechanism which permits alternate monitoring of precordial sounds as well as blood pressure is the Ploss Valve made by the 3M Companv. (Fig. 2) With the blood pressure
be prepared by an impression of the anesthetist's external auditory canal and molded in soft silastic rubber. Some standard ear pieces are available on the market which fit most ears. The indwelling molded ear piece makes monitoring more comfortable and continuous. It also frees up the listener's hands.
A number of electronic blood pressure monitors are available. One of these is the digital blood pressure device called Vital-II made by Meditron Instrument Corp. in Milford, New Hampshire. This is a portable, semi-automatic digital blood pressure monitor. This instrument automatically shows and stores in a bright numeric display the systolic and diastolic pressures. It operates on rechargeable batteries or
it can be operated on a standard 110 volt a.c. outlet. Another electronic blood pressure meter is made by Healthdyne, Inc.
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