Michael H. Bishop

Prospective, randomized trial of survivor values of cardiac index, oxygen delivery, and oxygen consumption as resuscitation endpoints in severe trauma.

The objective was to test prospectively supranormal values of cardiac index (CI), oxygen delivery index (DO2I), and oxygen consumption index (VO2I) as resuscitation goals to improve outcome in severely traumatized patients. We included patients > or = 16 years of age who had either (1) an estimated blood loss > or = 2000 mL or (2) a pelvic fracture and/or two or more major long bone fractures with > or = four units of packed red cells given within six hours of admission. The protocol resuscitation goals were CI > or = 4.5 L/min/m2, DO2I > or = 670 mL/min/m2, and VO2I > or = 166 mL/min/m2 within 24 hours of admission. The control resuscitation goals were normal vital signs, urine output, and central venous pressure. The 50 protocol patients had a significantly lower mortality (9 of 50, 18% vs. 24 of 65, 37%) and fewer organ failures per patient (0.74 +/- 0.28 vs. 1.62 +/- 0.45) than did the 75 control patients. We conclude that increased CI, DO2I, and VO2I seen in survivors of severe trauma are primary compensations that have survival value; augmentation of these compensations compared to conventional therapy decreases mortality.

Unreliability of blood pressure and heart rate to evaluate cardiac output in emergency resuscitation and critical illness

ObjectiveTo evaluate the reliability of the vital signs to evaluate circulatory stability as reflected by cardiac index. DesignDescriptive analysis based on data gathered prospectively, using a predetermined protocol. SettingUniversity-run county hospital, with a large trauma service. PatientsSixty-one high-risk trauma patients with accidental injury who were studied immediately after admission to the Emergency Department, and subsequently, 163 critically ill postoperative ICU patients. InterventionsStandard fluid therapy, usually crystalloids, but occasionally packed red cell transfusions and colloids, as indicated by clinical criteria. Measurements and ResultsArterial BP was measured by pressure transducer and arterial catheter; heart rate (HR) was measured by electrocardiograph signal, and cardiac output was measured by thermodilution. In sudden severe hypovolemic hypotension, the mean arterial pressure (MAP) nadir (lowest) roughly correlated (r2 = .25) with flow, but there was poor correlation (r2 s .0001) when all pressure and flow values were evaluated. The pressure and flow values were obtained throughout the course of the hypotensive episodes during the initial resuscitation in ICU patients and during terminal illnesses. ConclusionsObservations at the time of acute severe hypotensive crises that show rough correlation of MAP and cardiac index should not be extrapolated throughout the entire hypotensive period or to other less extreme clinical situations. The stress response to hypovolemia, with endogenous catecholamines and neural mechanisms, tends to maintain arterial pressure in the face of decreasing flow for a variable period of time. However, when these mechanisms are overwhelmed by prolonged hypovolemia, the pressure decreases precipitously, but not synchronously, with flow. We conclude that blood flow cannot reliably be inferred from arterial pressure and heart rate measurements until extreme hypotension occurs. (Crit Care Med 1993; 21:218–223)

Temporal patterns of hemodynamics, oxygen transport, cytokine activity, and complement activity in the development of adult respiratory distress syndrome after severe injury.

The aim of this study was to search for early inflammatory mediators in severely traumatized patients that could predict the occurrence of adult respiratory distress syndrome (ARDS). We measured sequential plasma levels of tumor necrosis factor (TNF), interleukin 1 (IL-1), interleukin 6 (IL-6), interleukin 8 (IL-8), complement fragment C3a, and endotoxin. In addition, we measured sequentially the values of hemodynamics, oxygen transport, and pulmonary function. The temporal patterns seen in the patients who developed ARDS were compared with those who did not. In the patients who developed ARDS, the first observed findings were low cardiac index (CI) and oxygen delivery (DO2) followed by progressive increases in IL-6, IL-8 and C3a levels, worsening of pulmonary function, and increases in hemodynamic values. The maximum values of IL-6, IL-8, and C3a occurred after the onset of ARDS. In the patients who did not develop ARDS, initial oxygen transport values were not low, the levels of IL-6, IL-8, and C3a decreased rapidly from their initial peaks, and there were no further increases in hemodynamic values. In both ARDS and nonARDS patients, no measurable quantities of TNF, IL-1, or endotoxin were found. We concluded that none of the mediators we measured reached their peaks before the onset of ARDS and none were found to be predictive of posttraumatic ARDS. However, these and other mediators may augment or intensify the development of ARDS.

Sequence of physiologic patterns in surgical septic shock

Gradual, almost imperceptible transitions occur between localized infection, generalized infection, systemic manifestations of the sepsis syndrome, septic shock, and death. The aim of this study was to describe the sequential pattern of hemodynamic and oxygen transport patterns of survivors and nonsurvivors of septic shock, so as to differentiate primary from secondary and tertiary events, to evaluate possible physiologic mechanisms, and to provide a template to relate the appearance of biochemical mediators to the sequence of physiologic events. Design:Prospective, cohort study. Setting:University-run county hospital. Patients:A series of 300 consecutive surgical patients with septic shock; 85 survived and 215 died. Interventions:We used specific criteria to define stages as: a) early period, the first recorded increase in cardiac output; b) middle period, time of maximal metabolic activity defined as the highest recorded oxygen consumption (Vo2); and c) late period, the time of death or recovery. Measurements and Main Results:Hemodynamic and oxygen transport variables were measured at frequent intervals throughout the course of septic shock.Beginning with increased cardiac index and oxygen delivery (Vo2), which were the earliest observed hemodynamic changes, there were progressive increases in cardiac index, Vo2, and Vo2 The values of these variables in the survivors were both greater than normal and greater than those values of the nonsurvivors at comparable time periods. These values decreased in the late stage in nonsurvivors.There were early transient reductions in Vo2 that preceded the increase in temperature and the decrease in blood pressure in both survivors and nonsurvivors. Although 86% of the septic patients were hyperdynamic, there were transient hypodynamic episodes (defined as cardiac index <2.5 L/min/m2) in <10% of the measurements. Transient preterminal hypermetabolic periods occurred in 9% of the nonsurvivors. Conclusions:Increased cardiac index and Vo2 represent compensations for circulatory deficiencies that limit body metabolism, as reflected by inadequate Vo2Survivors have higher cardiac index, Vo2 and Vo2 values than those values of both the nonsurvivors and normal values. These data suggest that therapy should be directed toward increasing cardiac index to >5.5 L/min/ m2, Vo2 to >1000 mL/min/m2, and Vo2 to >190 mL/ min/m2 as therapeutic goals; these supranormal values were empirically determined by the patterns of the survivors. Further studies to describe temporal relationships of biochemical mediators of these physiologic patterns are needed. (Crit Care Med 1993; 21:1876–1889)

Temporal patterns of radiographic infiltration in severely traumatized patients with and without adult respiratory distress syndrome.

We prospectively evaluated the patterns of pulmonary structural and functional changes in 100 consecutive surgical intensive care unit trauma patients who had (1) emergent major surgery, (2) a pelvic fracture, or (3) two or more major long bone fractures. For each patient, arterial blood gas measurements (ABGs), central venous pressure (CVP), pulmonary capillary occlusion pressure (PAOP), thoracic compliance, arterial oxygen tension/fraction of inspired oxygen (PAO2/FIO2), pulmonary venous admixture (Qs/Qt), and portable chest roentgenograms were sequentially tracked. The senior staff radiologist interpreted all chest roentgenograms. Pulmonary infiltration was quantitated in each of six fields using a scale ranging from 0 to 4, with 0 being no infiltration and 4 being the maximum. Adult respiratory distress syndrome (ARDS) was defined as follows: Qs/Qt > or = 20%, PAO2/FIO2 < 250 or both; dependence on mechanical ventilation for life support for > or = 24 hours; PAOP or CVP or both < 20 mm Hg; and thoracic compliance < 50 mL/cm H2O. Time zero (T0) the time of onset of ARDS, was defined as the time these criteria were met. Eighty-three of 100 study group patients had penetrating injuries, and 17 were admitted with blunt trauma. Fifty-one of 100 patients developed ARDS: 36 of 51 died. Only 4 of 49 (8%) patients without ARDS died. The injured lungs of patients with and without ARDS had similar amounts of infiltration over most measured time intervals. The noninjured lungs of the ARDS patients, however, had significantly greater infiltration than those without ARDS at T0 and over subsequent time intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of radiographic infiltration versus pulmonary function in severely traumatized patients with and without adult respiratory distress syndrome: Correlation of lung structure and function

AbstractLung structural changes were evaluated by radiographic infiltration and compared with functional changes by pulmonary venous admixture or shunt (

Relationship between supranormal circulatory values, time delays, and outcome in severely traumatized patients.

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Temporal Hemodynamic and Oxygen Transport Patterns in Medical Patients: Septic Shock

) and blood gases (PaO2/FiO2 ratio, which is the ratio of arterial oxygen tension to oxygen concentration of inspired gas) in 70 consecutive severely traumatized patients. Of these, 36 (51%) developed adult respiratory distress syndrome (ARDS) by clinical and physiologic criteria, and 34 (49%) did not develop ARDS; 42 patients sustained direct pulmonary injury from penetrating stab or gunshot wounds; 24/36 (67%) of those with ARDS and 28 (40%) of the entire series died.The study showed a rough direct correlation of a semiquantitative infiltration score with pulmonary shunt and an indirect correlation with the PaO2/FiO2 ratio during the initial resuscitation and the subsequent posttrauma course in both ARDS and non-ARDS patients. The temporal pattern of the infiltration score closely paralleled that of the pulmonary shunt pattern and inversely paralleled the PaO2/FiO2 ratios throughout the period of observation, indicating that radiographic structural changes developed concomitantly with functional changes.To avoid confounding issues, we studied only young, previously healthy trauma victims without head injury. Data from patients with direct lung injury were stratified and evaluated separately. The earliest observed changes most often occurred in the upper and middle lung fields; by contrast, most mechanically ventilated trauma patients had varying degrees of infiltration in the bases with some dysfunction, but not enough to meet ARDS diagnostic criteria.