Prospective Trial of Supranormal Values of Survivors as Therapeutic Goals in High-Risk Surgical Patients: Materials and Methods

In: Surgical Patients

10 Mar 2015

Clinical Series: Entrance Criteria
This study was approved by the hospitals Institutional Review Board and informed consent was obtained from each patient; no proxy consents were used. Entrance criteria for selection of high-risk patients were previously defined as one or more of the high-risk criteria listed in Table 1. Over the past seven years, patients who met one or more of these criteria had been found to have a mortality rate close to 30 percent. Series 1 consisted of 276 operations on 252 high-risk general surgical patients; PA-monitoring in 96 (35 percent) of these was not started until the postoperative period. Patients were stratified into those whose hemodynamic monitoring was started preoperatively and those whose monitoring was started postoperatively. We also compared groups who preoperatively had relatively normal cardiac output values with those who had grossly abnormal preoperative cardiac output values.

In series 2, 146 general surgical patients met one or more of these criteria and were eligible for the study. Of these 146 patients, 55 were operated on without randomization; ten of these went directly to the operating room as emergencies before informed consent could be arranged, and 45 patients were not randomized (NR group) by the choice of the service physicians because they were not considered ill enough to justify invasive monitoring. Three patients were randomized, but subsequently their operations were cancelled. The remaining 88 patients were prospectively allocated to one of the three groups designated by cards arranged according to a random numbers table by an outside person and placed in opaque sealed envelopes. The envelopes were opened in sequence as soon as the patient consented to the study. During this period of observation, 7 percent of 2,086 patients operated on by the general surgical service were preoperatively identified on clinical grounds as being at high risk. This high-risk group accounted for 82 percent of the general surgical services’ mortality.
Table 1—Criteria for High Risk and Their Distribution to Therapeutic Groups

Criteria PA-Control PA-Protocol CVP Series 2 (N = 30)
Series 1 (N = 151) Series 2 (N = 30) Series 1 (N = 101) Series 2 (N = 28) Not Randomized (N = 45)
Previous severe cardiorespiratory illness (acute MI, COPD, stroke, etc) 7 6 4 5 7 14
Extensive ablative surgery planned for carcinoma; eg, esophagectomy and total gastrectomy, prolonged surgery (>8 h) 39 4 17 7 6 3
Severe multiple trauma, eg, >3 organs or >2 systems, or opening 2 body cavities 29 0 21 1 0 0
Massive acute blood loss (>8 units), BVC1.5 L/m2, Hct <20% 6 0 12 1 4 1
Age over 70 years and evidence of limited physiologic reserve of one or more vital organs 36 1 24 5 6 5
Shock, MAP<60 mm Hg, CVP<15 cm H20, and U0<20 ml/h 2 1 3 1 0 0
Septicemia, positive blood culture or septic focus,WBC> 13,000, spiking fever to 101°F for 48 h, and hemodynamic instability 39 3 31 1 5 1
Respiratory failure, eg, Pa02<60 on FIo2>0.4, Qsp/Qt>30%, mechanical ventilation needed >48 h 0 2 0 0 4 0
Acute abdominal catastrophe with hemodynamic instability, eg, pancreatitis, gangrenous bowel, peritonitis, perforated viscus, GI bleeding 22 13 17 8 16 11
Acute renal failure (BUN>50 mg/dl, creatinine >3 mg/dl) 0 1 0 0 4 0
Late stage vascular disease involving aortic disease 5 6 2 5 2 2

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