Pediatric trauma registries: the foundation of quality care.

BACKGROUND/PURPOSE: Traumatic injuries cause substantial morbidity and mortality in children. Trauma registries are essential to assess and improve standards of trauma care. An interprovincial study of pediatric trauma between 6 centers across Canada who use identical software components was completed. METHODS: Data were collected from April 1, 1995 to December 31, 1998 for children aged 1 day to 17 years with an injury severity score of > or = 12. Cause of injury, injury time and day, gender, age, injury scores, length of hospital stay, and outcomes were compared. RESULTS: A total of 1,276 patients were included. Mean age was 10.3 +/- 5.6 years. Motor vehicle collisions were the most common mechanism of injury (56%). Boys were more often injured (66%; P < .05). Injuries occurred mainly between 1600 and 2400 hours (P < .0001). Mean hospital stay was 11.5 +/- 16.6 days. The longest stays in the hospital were among those who had an abdominal abbreviated injury score (AIS) of 1 (P < or = .03). Patients with similar injury severities remained twice as long in Winnipeg Children's Hospital (hospital 5), hospital 2, and hospital 6 as compared with patients in hospital 3 (P < .05). Differences existed in discharge placement between hospitals (P < .0001). CONCLUSIONS: This study was the first to compare pediatric patients in multiple Canadian centers using identical trauma registries. Variations in length of stay and discharge placements between hospitals were identified. Further analysis of data in the registries may clarify these differences and serve as a foundation for hospitals to improve the quality of patient care.

Clinically significant gastrointestinal bleeding in critically ill patients in an era of prophylaxis.

OBJECTIVE: Clinical studies examining stress-related gastrointestinal bleeding in critically ill patients vary in their clinical definitions and assessment of clinical significance. Although there is evidence that routine prophylaxis decreases stress-related gastrointestinal bleeding, recent studies indicate a decreasing incidence, independent of the use of prophylactic medications. The purpose of this study was to determine the incidence of and risk factors for clinically significant, endoscopically proven gastrointestinal bleeding in critically ill patients. METHODS: A database (prospectively collected data) of 8338 patients admitted to the surgical and medical intensive care units at major tertiary care center from July 1988 to April 1995 was examined. All patients with significant upper gastrointestinal bleeding as defined by a drop in hemoglobin of >20 g/L and endoscopic evidence of an upper GI tract source were identified. Risk factors for GI bleeding from stress ulceration were compared in bleeding and nonbleeding patients. A case-control study analyzing risk factors for bleeding in the abdominal aortic aneurysm subgroup was performed. RESULTS: After exclusion criteria, 12/7231 (0.17%) patients had clinically significant, endoscopically proven bleeding. Significant risk factors included age, septic shock, abdominal aortic aneurysm repair, and nutritional support. Intensive care unit stay was prolonged in patients with stress-related bleeding. There was no difference in incidence of hypotension, clamp time, APACHE score, or operating room time in patients with abdominal aortic aneurysm repair as compared with controls. CONCLUSIONS: In an intensive care unit where stress prophylaxis is widely used, clinically important gastrointestinal bleeding is uncommon. Further study is needed to define the optimal prophylaxis regimen and the role for its selective use in high-risk patients.

Pulmonary oedema in isolated lung lobe after inhalation injury.

Pulmonary oedema was produced in isolated lung lobes with steam and provided direct continuous measurements of transudation as it occurred. Transvascular flux (Qf) and weight gain (Gw) of the lobe increased immediately and the transudation reached its peak within half an hour after inhalation injury. Studies of protein content, colloid osmotic pressure of bronchial exudate and water content of lung, reconfirmed the increase in pulmonary capillary permeability. Marked haemoconcentration was revealed. Plasma leaked 113 g (25 per cent), plasma protein leaked 1.96 g (9.7 per cent) during the experiment. Based on the measured arterial pressure (Pa), vein pressure (Pv), arterial occlusion (Pao), venous occlusion (Pvo), double occlusion (Pdo) and blood flow through the lobe (Qt), the total vascular (Rt), arterial (Ra), middle compartment (Rmid) and venous (Rv) resistances were calculated. All the resistances were increased and the Qt showed a decrease after inhalation injury.

Slow phase of transvascular fluid flux reviewed.

In six circuit experiments using a clinical hemofiltration device, we validated a colorimetric technique to measure transvascular volume exchange (VE). In 12 isolated excised canine left lower lobes, continuous colorimetric measurements of VE correlated well with calculations of VE from changes in microhematocrit obtained simultaneously. We introduced step increases in microvascular hydrostatic pressure (Pc) of 9 +/- 4.8 (SD) cmH2O and followed the time course of weight and continuous hematocrit changes measured colorimetrically for 40 min, after which Pc was returned to base line, while measurements were continuously obtained. This procedure was repeated for an additional 30 min. VE was calculated from the hematocrit signals and compared with the time course of the weight signal. After increases in Pc, followed by a rapid weight gain, weight signals followed a slow exponential time course, whereas the calculated VE changed linearly. VE reflected approximately 60% of the slow weight gain. When Pc was decreased, weight signals decreased exponentially, whereas VE continued to increase linearly at a slower rate. These results suggest that a significant component of the slow weight signal represents slow vascular volume changes. Contrary to what the weight signal suggested, edema was never reabsorbed over the range of Pc measured.

Vascular properties of canine lungs perfused with Eurocollins solution and prostacyclin.

Although Eurocollins solution (ECS) is commonly used for lung preservation, its vascular effects and their time course and response to pharmacological interventions are not well understood. The effect of 4 degrees C ECS on the pulmonary circulation was assessed in excised canine left lower lobes. The roles of static oxygen inflation and prostacyclin infusion during ECS perfusion were also examined. The lobes were divided into five groups: time control (A), ECS with oxygen (B), ECS without oxygen (C), ECS with glycine buffer (D), and ECS with prostacyclin (E); group D was the control for E. Eurocollins solution had no effect on gas exchange but had a marked effect on the pulmonary circulation. Vascular conductance decreased from 22.6 to 18.9 mL/min/cm H2O and from 21.3 to 14.1 mL/min/cm H2O with average vascular closure increasing by 1.2 and 2.1 cm H2O in groups B and C, respectively. The decreased vascular conductance and increased vascular closure was associated with a reduction in vascular compliance from 1.63 to 1.25 mL/cm H2O. When prostacyclin was added to ECS, the reduction in vascular closure was much less and was associated with a decrease in vascular closure and no loss of vascular compliance. Eurocollins solution increases pressure cost for perfusion by causing both vascular obstruction and increased tone, especially when oxygen is not provided. This is significantly overcome by addition of prostacyclin infusion during ECS perfusion.

Do transvascular forces in isolated lobe preparations equilibrate?

We used the stepwise pressure elevation technique to study the relationship between rate of constant weight gain (Qf) and microvascular pressure (Pc) in eight isolated canine left lower lobes. The slope of this relationship, which is assumed to represent lobar conductance to filtration (Kf) was 0.0022 +/- 0.003 ml.min-1.cmH2O-1.g dry wt-1. The intercept when Qf = 0, Pcrit, commonly interpreted as the Pc at which the balance of forces across the microvasculature is overwhelmed, was 9.53 +/- 1.18 cmH2O, a lower Pc than commonly used in weight transient experiments. Consequently, at Pc greater than 9.53 cmH2O, isogravimetric conditions were never achieved. In 12 additional experiments, the perfusate's colloid osmotic pressure (II) was increased from 12 to 37 mmHg with albumin. On average, Pcrit increased from 12.2 to 23 cmH2O. Using the changes in Pcrit and II, we estimated the microvascular drag reflection coefficient for albumin (sigma d) to be 0.67. After the addition of albumin, Pc less than Pcrit induced constant weight loss along the same Qf-to-Pc relationship. To control for time, five additional lobes were observed at constant Pc for 100-180 min. Slight acceleration of the rate of weight gain occurred after they increased their weight by 30-40%. The low Kf and high sigma d, as well as the stability of the preparation, suggest a well-preserved microvasculature. Qf at Pc between 12 and 24 cmH2O did not influence measurements of Kf using the weight transient method. The low Pcrit may reflect obliteration of lymphatic channels.

Fast-phase transvascular fluid flux and the Fahraeus effect.

Transvascular fluid flux was induced in six isolated blood-perfused canine lobes by increasing and decreasing hydrostatic inflow pressure (Pi). Fluid flux was followed against the change in concentration of an impermeable tracer (Blue Dextran) measured directly with a colorimetric device. The time course of fluid flux was biphasic with an initial fast transient followed by a slow phase. Hematocrit changes unrelated to fluid flux occurred due to the Fahraeus effect, and their contribution to the total color signal was subtracted to determine the rate of fast fluid flux (Qf). Qf was related to Pi to derive fast-phase conductance (Kf). Slow-phase Kf was calculated from the constant rate of change of lobe weight. For a mean change in Pi of 7 cmH2O, 40% of the color signal was due to fluid flux. Fast- and slow-phase Kf's were 0.86 +/- 0.15 and 0.27 +/- 0.05 ml X min-1. cmH2O-1 X 100 g dry wt-1. The fast-phase Kf is smaller than that reported for plasma-perfused lobes. Possible explanations discussed are the nature of the perfusate, the mechanical properties of the interstitium, and the slow rate of rise of the driving pressure at the filtration site on the basis of a distributed model of pulmonary vascular compliance.

Colorimetric device for measurement of transvascular fluid flux in blood-perfused organs.

The aim of this study was to develop a device capable of measuring transvascular fluid flux in blood-perfused organs. For any given blood flow through the organ (QT), transvascular flux (QF) can be considered as the fraction of QT exchange. Presumably, QF would change the background concentration of an impermeable tracer residing in the perfusate. Thus QF could be calculated from the relative changes in tracer concentration for any given QT. We have used Blue Dextran (1 g/l of blood) as the reference tracer. Because the minimum molecular weight of Blue Dextran is 2 X 10(6), we anticipated it to behave as an impermeable tracer in most organs. QF was simulated with continuous infusions of plasma, normal saline solution, and a 50% mixture of both. Changes in Blue Dextran concentration were continuously followed colorimetrically by changes in transmission of specific light at a wavelength of 632 nm. Because 632-nm light is affected by hematocrit and O2 saturation changes, two additional wavelengths were used: 815-nm, which is not affected by saturation or Blue Dextran concentration changes, was used to account for changes in hematocrit, and 887-nm specific light, which is not affected by Blue Dextran, served to correct for saturation changes. Red cells could not be used as the reference tracer because of the possibility of hematocrit changes independent of fluid flux (Fahraeus effect). The device so constructed proved capable of measuring rates of fluid infusion in the order of 0.1% of QT with a variability of 10% around the mean.