The availability of circulating blood volume values alters fluid management in critically ill surgical patients.

BACKGROUND: This study evaluated whether commercially available blood volume measurements in critically ill surgical patients altered fluid management. METHODS: Patients admitted to the surgical intensive care unit of a tertiary care teaching hospital were prospectively evaluated. The frequency of changes in fluid management when results of blood volume measurements were available was determined. RESULTS: In a pilot study, the frequency of instances when measurement of blood volume would have altered fluid management was statistically significant (P = .0003). In 40 subsequent patients, treatment change occurred in 36% of instances when blood volume results were obtained (P < .001). In the majority, no immediate qualitative change in clinical status occurred, with a desirable clinical response in 39% and no negative treatment responses (P < .001). CONCLUSIONS: Blood volume measurements may assist in the management of critically ill surgical patients by providing a direct measure of intravascular volume. Further studies are warranted to determine its effect on outcome.

Using transcutaneous oxygen pressure measurements as selection criteria for activated protein C use.

BACKGROUND: Limited resources and the expense of Activated Protein C (APC) (drotrecogin alfa) may contribute to the reluctance to utilize this drug in sepsis. Employing the PROWESS criteria resulted in absolute reduction in 28-day mortality of 6.1%, representing a relative risk reduction of 19.4%. Additional patient categorization and selection may lead to less frequent drug use with the same survival advantage. We used transcutaneous partial pressure of oxygen (PtcO2) as an indicator of microcirculatory perfusion to identify which septic patients may benefit from APC. METHODS: Nineteen patients consecutively admitted with severe sepsis or septic shock that fulfilled the PROWESS criteria for APC treatment. APC was administered to patients with the PROWESS selection criteria, only if the PtcO2 information demonstrated tissue ischemia. RESULTS: Nineteen patients met the PROWESS criteria. Ten patients demonstrated poor tissue perfusion using PtcO2 monitors and received APC. Nine patients had adequate tissue perfusion and did not receive APC. There were no differences in age, gender, APACHE II scores, lactate levels, or organ failure between the two groups. The 10 patients who received APC had a mortality of 3 of 10 (30%). The survivors of this group uniformly converted to PtcO2 values consistent with survival within 12 hours to 24 hours of drug administration. The nine patients who did not receive APC had a mortality of 2 of 9 (22%), not statistically significant from those who received the drug (p = 0.89). CONCLUSION: Withholding APC did not result in an increase in mortality from severe sepsis in those patients who demonstrated adequate PtcO2 values. The transcutaneous oxygen measurement may be a useful adjuvant in addition to the other selection criteria for better identification of patients who may benefit from APC.

Peripheral blood hematocrit in critically ill surgical patients: an imprecise surrogate of true red blood cell volume.

BACKGROUND: Peripheral blood hematocrit (red blood cell volume/total blood volume) is conventionally used to determine the need for blood transfusions. In critically ill surgical patients, this variable may not accurately approximate true red blood cell volume. We compared peripheral blood hematocrit to (1) plasma volume, (2) estimated circulating blood volume, and (3) a normalized hematocrit to clarify their relationships. METHODS: Consecutive patients admitted to the surgical intensive care unit were evaluated using the BVA-100 Blood Volume Analyzer (Daxor Corporation, New York City, NY). Plasma volume was directly measured by serial tagged albumin concentration. Red blood cell volume was calculated using plasma volume and the peripheral blood hematocrit result. All volumes were presented as percentage deviation from ideal volumes. These ideal volumes were obtained using a patented formula incorporating ideal body weight as determined by Metropolitan Life tables. The peripheral blood hematocrit was compared with a "normalized" hematocrit, defined as the hematocrit value if plasma volume was adjusted to a normal whole blood volume. RESULTS: Eighty-six data points were recorded for 40 patients with average age 61 +/- 20 yr, APACHE II score 20 +/- 6, and a 13% mortality rate. The primary reasons for admission were severe sepsis/septic shock (n = 11), hemorrhagic shock (n = 7), respiratory failure (n = 20), and cardiac failure (n = 2). Bland-Altman analysis showed a mean difference of 3.4 +/- 7.8 hematocrit percentage points between normalized and peripheral blood hematocrit methods, with a 95% confidence interval of 1.7-5.1 and limits of agreement of +/-15.2 hematocrit percentage points. Peripheral blood hematocrit was lower than the normalized hematocrit in 48% of measurements, higher in 17%, and equivalent in 35%. CONCLUSIONS: Peripheral blood hematocrit may not accurately estimate red blood cell volume in a cohort of critically ill surgical patients. This remains to be validated in a larger group of patients, comparing these results with the double isotope technique.

Circulating blood volume measurements correlate poorly with pulmonary artery catheter measurements.

BACKGROUND: Determination of the intravascular volume status of a critically ill surgical patient is paramount for appropriate fluid and cardiovascular management. Many clinical parameters have been utilized to estimate intravascular volume but none are precise indicators of circulating blood volume. The purpose of this observational pilot study was to compare measured blood volume with hemodynamic parameters obtained from the pulmonary artery catheter and to determine if incorporation of these measurements altered treatment decisions in critically ill surgical patients. METHODS: Blood volume measurements were prospectively obtained in twenty surgical intensive care unit patients with a pulmonary artery catheter when intravascular volume status was deemed uncertain by traditional clinical parameters. RESULTS: There was a statistically significant, but weak, correlation between blood volume results and pulmonary artery occlusion pressure, but no correlation with central venous pressure, cardiac index, and stroke volume index. Blood volume information altered treatment in 21% of instances, and 5 of these 6 patients demonstrated a favorable clinical response. CONCLUSIONS: Circulating blood volume measurements may be useful in critically ill surgical patients when clinical appraisal of intravascular volume is uncertain. This remains to be validated in a larger, prospective randomized trial.

Traumatic brain injury: outcomes from rural and urban locations over a 5-year period (Part 1).

The national death rates from rural trauma are disproportionately higher compared to urban areas. Traumatic brain injury is a major cause of hospital admissions in Hawai'i. This is the first in a two part series to explore this significant public health concern. Data on traumatic brain injuries from 2000-2004 was obtained from 2 sources. Male gender, alcohol use, and lack of protective devices resulted in higher rates of injury. Rates of severe injury were higher in young adults, the elderly, and in rural locations, but rural mortality rates here did not differ compared to urban settings. The greatest potential to reduce morbidity and mortality resides in the formulation and implementation of preventive strategies.

Hypothyroidism and adrenal insufficiency in sepsis and hemorrhagic shock.

HYPOTHESIS: We hypothesized that hypothyroidism and adrenal insufficiency frequently occur together in critically ill patients. DESIGN: A prospective observational study. SETTING: Surgical intensive care unit of a university-affiliated tertiary referral center. PATIENTS: Sixty-six consecutive patients with severe sepsis, septic shock, and hemorrhagic shock who required pulmonary artery catheterization for resuscitation were studied. INTERVENTIONS: Thyrotropin and baseline cortisol levels were obtained at 3 am followed by intravenous injection of 250 mug of cosyntropin, a synthetic adrenocorticotropic hormone derivative. A second measurement of the cortisol level was performed 1 hour later. MAIN OUTCOME MEASURES: Incidence of hypothyroidism and adrenal insufficiency and mortality. RESULTS: Mean (SD) age was 62 (19) years. The mean (SD) Acute Physiology and Chronic Health Evaluation II score was 21 (5). Twenty-seven patients (40.9%) had severe sepsis, 31 (46.9%) had septic shock, and 8 (12.1%) had hemorrhagic shock. Five patients (7.6%) had hypothyroidism alone and 35 (53.0%) had only adrenal insufficiency. Eight patients (12.1%) had both hypothyroidism and adrenal insufficiency. All patients with endocrine abnormalities were treated. Mortality for the total group was 15 (22.7%) of 66 patients. CONCLUSION: There is a 12% incidence of simultaneous hypothyroidism and adrenal insufficiency in our study and the routine testing for both may be indicated in this population of critically ill patients.