Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (14)
Many factors affect circulatory function and metabolism, such as age, trauma, sepsis, stress, nutrition, metabolic diseases such as diabetes, medications, anesthetic agents, drug abuse, hypovolemia, and other associated illnesses. These and many other influences may be operative and may limit circulatory compensations. Notwithstanding, it is the amount of the Vo2 debt that is related to organ failure and outcome. Moreover, oxygen debt is the earliest circulatory event observed with lethal and nonlethal organ failure.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (12)
The first three of these are probably the most important.
Sources of error in the proposed approach include interpolation between the measured data sets in order to calculate the cumulated Vo2 deficit. Over 10,000 sets of measurements with more than 100,000 values of oxygen transport and metabolism were performed in the present study. It is doubtful if more measurements, or even continuous measurements, would produce materially different results. Moreover, it would be difficult for the data to be biased because the outcome of each patient was not known when the measurements were taken and recorded.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (11)
Previous studies had demonstrated reduced Vo2 during and immediately after surgical trauma from inadequate or maldistributed blood flow and reduced tissue perfusion. The first part of the present study, which is purely descriptive, documents greater tissue oxygen deficits in patients who subsequently develop multiple organ failure than in patients without organ failure. In lethal cases, the oxygen deficits were greater in magnitude and duration. Moreover, the very early appearance of oxygen debt suggests that reduced tissue oxygenation is the primary event, while organ failure and death are the result of this antecedent physiologic event.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (10)
Specific Organ Failures and Times of Onset
Table 5 details the number of types of organ failure in nonsurvivors and survivors. There were 1.72 organ failures per nonsurvivor and 1.42 organ failures per survivor with organ failure, or 0.28 organ failures for all survivors. Table 6 lists the complications in the survivors and nonsurvivors. In nonsurvivors the organ failures in decreasing order of frequency were as follows: pulmonary, sepsis, cardiac, renal, DIC, and CNS failure. There were similar distributions of organ failures, except for somewhat greater numbers of pulmonary failures and fewer cardiac problems, in the survivors.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (8)
Patterns of Hemodynamics and Oxygen Transport
The patterns of selected hemodynamic and oxygen transport variables of surviving and nonsurviving high-risk surgical patients in the preoperative, intraoperative, and immediate postoperative periods are shown in Figure 2. Cardiac index, Do2, and Vo2 of survivors without organ failure were highest, those who survived with organ failure were intermediate, while the values of those who subsequently died were lowest but within the normal range. There were no other hemodynamic or oxygen metabolic changes that were appreciable or statistically significant in the early postoperative period. In general, the survivor-nonsurvivor patterns were consistent with previously reported series.’
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (7)
Statistical analyses of the sequential patterns of variables before, during, and after operation were performed using the analysis of variance (ANOVA) and the Newman-Keuls test. The x2 and Student t tests were used to compare the number of organ failures in survivors vs nonsurvivors and in control vs protocol groups and the times of onset of organ failure. Values for p less than 0.05 were considered significant.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (6)
Calculation of Tissue Oxygen Debt
The Voa need was estimated from the patients own baseline preoperative Vo2 corrected for the effects of temperature and anesthesia. The temperature correction assumed metabolic activity increased or decreased 7 percent per degree Fahrenheit; ie, the temperature corrected Vo2 (Vo2c) was calculated as follows: Vo2c = Vo2x ; where T is the patients core temper ature in degrees Fahrenheit. Lowe and Ernst reported the following for the Vo2 of patients under anesthesia: Vo2 (anesth) = 10 x kg”. This value, also corrected for temperature, was used for calculation of the Vo2 need during the time the patient underwent general anesthesia. After the effects of the anesthetic were reversed after surgery, the temperature-corrected Vo2 was used.
Role of Oxygen Debt in the Development of Organ Failure Sepsis, and Death in High-Risk Surgical Patients (5)
There were 36 risk factors in the control group and 34 in the protocol group. Based on a ten-yr study of the high-risk preoperative criteria, the mortality in the control group would be expected to be 33 percent and in the protocol group 28 percent.
The therapeutic goals in the control group were normal values, while those in the protocol group were empirically determined from survivors. The therapy for both groups was the same: crystalloid, colloids, packed red blood cells, inotropic agents, and vasodilators; the difference between the two groups was the goals of therapy.