Elucidation of the underlying dysfunction must depend upon the time-honored triad of history, examination, and special investigations.
Emphasis must be placed on determining the limit of physiological reserve, particularly of the cardiorespiratory system. The intention is to identify those patients who will benefit from further investigation and more complex perioperative management in the intensive care unit (ICU) ( .S.h.,o.e.m.a.keL£Í,a( 1988; Boyd et.,§L 1993). The history should also inquire into limitation of physiological reserve in other organ systems.
Examination should specifically attempt to determine the degree of physiological limitation that may have been noted from the history. In particular, physical signs of cardiac failure should be noted, as these have been shown to be good predictors of postoperative morbidity and mortality.
Emphasis must be on defining abnormalities of cardiorespiratory performance and organ perfusion. Selection of the appropriate tests and investigations ( Table !) should be individualized. Preoperative investigations are aimed at defining the extent and nature of any physiological incapacity and identifying potential avenues of treatment. It may not be possible to ameliorate long-standing medical conditions completely, but these should be treated wherever possible. When complete treatment cannot be effected in the time available, investigations should elucidate the degree of outstanding physiological deficit. The actual choice of investigation is difficult, and is a balance between the information accrued by the new investigation and the time taken to perform the test.
Table 1 Investigative studies which should be considered
Once basic resuscitation has been performed, management should be directed towards optimizing the intravascular volume and cardiac performance to maintain tissue perfusion and tissue oxygen supply.
On the basis of history, examination, and preliminary investigations patients can be classified as those with myocardial impairment, those with intravascular volume depletion, or those with both. Management must be directed toward optimizing the intravascular fluid volume and consequently improving myocardial performance to ensure adequate tissue perfusion. For descriptive purposes patient management will be discussed under three main headings: optimizing intravascular fluid volume, improving myocardial and circulatory performance, and improving organ perfusion. There is a large overlap between these three areas, and appropriate therapy should be directed to all of them simultaneously whenever possible.
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