EVIDENCE-BASED MANAGEMENT OF CRITICALLY ILL PATIENTS

Quality of Evidence

To determine the value of a clinical intervention, it is important to evaluate the quality of the study on which it is based. A number of groups have developed criteria with which evidence can be graded. The Oxford Centre for Evidence-Based Medicine has strict criteria for grading the level of evidence. These criteria are described in Table 74-3 . After the evidence level has been determined, specific practices can be graded using the previously described criteria. Only through rigorous clinical experimentation can we determine practices that will improve the outcomes of critically ill patients. Equally important is analysis of the cost-effectiveness of these interventions. Implementation may require fiscal and personnel expenditures, and it is the role of the medical director to convince hospital administrators of the cost-effectiveness of new interventions. Figure 74-1 describes the cost-effectiveness relationship for a theoretical treatment.

Care of critically ill patients has been revolutionized by technology and drug development, but an equally important contribution has come with the application of evidence-based medicine to critical care practice. Whereas critical care initially focused on trying to restore homeostasis, there is increasing recognition that normal physiology is not always the most desirable therapeutic target. An important example of this principle is found in the management of patients with acute respiratory distress syndrome (ARDS). When patients with ARDS are mechanically ventilated with higher tidal volumes (12 mL/kg ideal body weight), they improve their oxygenation ratio. ^[9] However, these patients had significantly higher mortality rates than those mechanically ventilated with lower tidal volumes (6 mL/kg ideal body weight). This example and others illustrate the need for randomized, prospective trials of new and existing therapies.

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