Summary
Effective monitoring renuces the potential for poor outcomes that may follow anesthesia by identifying derangements before they result in serious or irreversible injury. Standards for basic anesthetic monitoring have been established by the American Society of Anesthesiologists (ASA). Today's standard (last amended on Octobe 25, 1995) emphasize the importance of regular and frequent measurements, integration of clinical judgment and experience, and the potential for extenuating circumstances that can influence the accuracy of monitoring systems. (ASA , 2003) .
Standard I reqUIres qualified personnel to be present in the operating room, to monitor the patient continuously and modify anesthesia care based on clinical obs~rvations and the responses of the patient to dynamic changes resulting from surgery or drug therapy. Standard II focuses attention on continually evaluating the patient's oxygenation, ventilation, circulation, and temperature ' and specifically
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mandates the following:
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1-Using an oxygen analyzer with a low concentration limit almm during
general anesthesia. 2-Quantitative assessment of blood oxygenation durink any anesthesia
care I 3-Continuously enSUrIng the adequacy of ventilati;bn by physical diagnostic techniques during all anesthesia cale. Quantitative
I monitoring of tidal vvolume and capnography encouraged in patients undergoing general anesthesia.
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hypoperfusion,causing loss of signal. several manufacturers have developed proprietary methods to address these problems based on analysis of frequency,waveform morphology,or saturation.Puplished evidence supports the ability of new generation pulse oximetry to detect hypoxemic episodes more. reliably than conventional devices under conditions of patient motion and hypo thennic hypoperfusion.(Irita k et aI, 2003)
Capnography, the measurement of C02 in expired gases,has evolved in the last few years into a comm nly used procedure. Whereas a variety of techniques can be used for C02 measurement( e.g., mass spectrometry, Raman analysis), most capnographs rely on infra red absorption. Use of this technique can reliably and quantitatively provide vital respiratory monitoring information in the operating room and in all critical care areas.(Graveenstein Js et ai, 2000).
PAC provides measurements of several hemodynamic parameters such as central venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary artery occlusion pressure(P AOP)or pulmonary capillary wedge pressure (PCWP) and other derIved parameters .. There have been a number of surveys to determine how well physicians, nurses, and other heal th care practitioners interpret PAC data. Even in the realm of idealized pressure tracings and data presentation, nurses/ American physicians, and European physicians[all incorrectly interpret the data in 25% to 50% of cases. This deficiency has been recognized by the National Institutes of Health and a variety of professional societies who have created initiatives and resources to improve PAC education. (PAC
education project, 2005) .
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It is difficult, and often impossible, by clinical evaluation of recovery of neuromascular function, to 'exclude with certainly clinically significant residual curarization.,so in daily practice significant residual block can be excluded with certainly only if objective methods of neuromascular monitoring are used. Good evidence -based practice dictates that clinicians should always quantitate the extent of neuromascular recovery using objective monitoring. At aminimum, the TOF ratio should be measured during recovery whenever a non depolarizing neuromascluar block is not antagonized.(Eriksson Li, 2003).
The effects of anesthesia and surgery on the eNS may be monitored by recording processed EEG activity, as in the bispectral index or the Patient State Index. These indices are used as measures of hypnosis,sedation, and the probability of recall using a variety of
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anesthetic agents (thiopental, propofol, midazolam, isoflurane, and sevoflurane). The use of the BIS can facilitate faster emergence and Improve recovery from general anes thesia by allowing more precIse titration of anesthetic effect . (Lehmann A et ai, 2002) .
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