The golden hour and the silver day: detection and correction of occult hypoperfusion within 24 hours improves outcome from major trauma

A Hemoglobin Based Oxygen Carrier, Bovine Polymerized Hemoglobin (HBOC-201) versus Hetastarch (HEX) in an Uncontrolled Liver Injury Hemorrhagic Shock Swine Model with Delayed Evacuation

BACKGROUND

As HBOC-201 improves outcome in animals with hemorrhagic shock (HS), we compared HBOC-201 and HEX (used by U.S. military special operations forces) in a swine model of delayed evacuation and uncontrolled HS.

METHODS

Twenty-four Yucatan pigs underwent a grade III liver injury and were resuscitated with HBOC-201, HEX, or no fluid (NON). Additional infusions were given for hypotension or tachycardia. After 4 hours, the liver was repaired; IV fluids and blood transfusions were administered. Pigs were monitored for 72 hours.

RESULTS

Survival was 7/8, 1/8, and 1/8 in HBOC-201-, HEX-, and NON-resuscitated pigs, respectively. Compared with HEX, HBOC-201 pigs had higher systemic and pulmonary artery pressures and had comparable cardiac outputs, but were less tachycardic. Transcutaneous tissue oxygenation was restored more rapidly in HBOC-201 pigs, there was a trend to lower lactic acid, and base deficit was less. HBOC-201 pigs had lower fluid requirements, higher urine output, and lower blood loss than HEX pigs.

CONCLUSIONS

Despite evidence of vasoactivity, HBOC-201 more effectively stabilized tissue oxygenation, reversed anaerobic metabolism, decreased bleeding, and increased survival in comparison with HEX. If confirmed in clinical trials, these data suggest that for the resuscitation of combat casualties with delayed evacuation and uncontrolled HS due to solid organ injury, HBOC-201 is a superior low-volume resuscitative fluid.

Sepsis in adults and foals

Sepsis develops in horses when the host response to the invading pathogens is not properly balanced according to the severity of the insult. Several clinical conditions frequently encountered in equine practice may be associated with the development of sepsis and have the potential to progress to more severe forms, such as severe sepsis, MODS, and septic shock. Consequently, it is important for equine practitioners to be aware of the manifestations,pathophysiology, and treatment of sepsis. Although enormous progress has been made in recent years in our understanding of the pathophysiology of sepsis. more work remains to be done in improving basic critical care guidelines and basic monitoring in equine intensive care units and in critically evaluating potential equine sepsis therapy. Fortunately, we can learn from the important advances made recently in the treatment of human sepsis patients;hence, rapid progress may be expected in a near future, especially as more and more veterinarians show interest in the discipline of equine critical care. With the completion of several genome projects and the availability of high-throughput genetic techniques, one hopes that we will further refine our understanding of the events underlying the development of severe sepsis and septic shock, which could lead to more appropriate therapeutic intervention targeted to each individual according to the state of the immune response in that horse.

Acute renal failure - definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group

INTRODUCTION

There is no consensus definition of acute renal failure (ARF) in critically ill patients. More than 30 different definitions have been used in the literature, creating much confusion and making comparisons difficult. Similarly, strong debate exists on the validity and clinical relevance of animal models of ARF; on choices of fluid management and of end-points for trials of new interventions in this field; and on how information technology can be used to assist this process. Accordingly, we sought to review the available evidence, make recommendations and delineate key questions for future studies.

METHODS

We undertook a systematic review of the literature using Medline and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated recommendations and/or directions for future research.

RESULTS

We found sufficient consensus on 47 questions to allow the development of recommendations. Importantly, we were able to develop a consensus definition for ARF. In some cases it was also possible to issue useful consensus recommendations for future investigations. We present a summary of the findings. (Full versions of the six workgroups' findings are available on the internet at http://www.ADQI.net)

CONCLUSION

Despite limited data, broad areas of consensus exist for the physiological and clinical principles needed to guide the development of consensus recommendations for defining ARF, selection of animal models, methods of monitoring fluid therapy, choice of physiological and clinical end-points for trials, and the possible role of information technology.

Comparison of bystander trauma care for moderate versus severe injury

At the scene of an accident, the most severely injured patients need trauma care urgently. Bystanders are often present before the emergency medical service arrives and may be able to limit trauma-related damage by providing trauma care at the scene. The aim of this prospective study conducted in Mainz, Germany, and Vienna, Austria, was to compare the frequency and quality of bystander trauma care in moderately versus severely injured patients. Five specific measures (making the scene readily visible for oncoming traffic, extrication and positioning of the trauma patient, control of haemorrhage, and hypothermia protection) were assessed in a questionnaire and evaluated statistically. Bystanders were present at the scene in 58.7% of all accidents. Making the scene readily visible for oncoming traffic, patient extrication and patient positioning were initiated significantly more often than haemorrhage control and hypothermia protection. Extrication, patient positioning and hypothermia protection were initiated significantly more often in moderately (NACA I-II) compared to severely (NACA III-VII) injured patients. In severely injured patients, bystanders attempted measures less frequently and the measures performed were more often incorrect compared to those in moderately injured patients. Our findings show that severely injured patients received less and less appropriate bystander trauma care than moderately injured patients. In an effort to correct this serious problem and to improve trauma care on-scene, we advocate offering lay persons more extensive training in bystander trauma care.

Point of care testing: improving pediatric outcomes

OBJECTIVE

Goal-directed therapy (GDT) has been proven to reduce morbidly and mortality in critical illness. Point of care testing (POCT) allows rapid turn around time (TAT) of critical data, yet data suggesting improved outcomes are very limited. The impact of these two strategies on improving outcomes for patients after congenital heart surgery has never been evaluated.

DESIGN

Beginning July 2001, POCT in the form of the i-STAT handheld analyzer was incorporated in the management of patients after congenital heart surgery at our institution. Blood lactate measurements were performed serially for 24 h after surgery. Based on a lactate value, medical therapy was escalated, diminished or left unchanged after surgery. Outcome data were collected prospectively for later review. Mortality at 30 days after surgery was compared for patients undergoing a GDT protocol to a group of historical cohorts. The operative risk for all operations was determined using the RACHS-1 scoring system.

SETTING

A 16-bed Cardiac Intensive Care Unit (CICU) in a 268-bed free-standing pediatric hospital.

PATIENTS

Outcomes of infants and neonates operated on from July 2001 through July 2003 (Group B) were compared to historical controls in our institution from June 1995 through June 2001 (Group A). There were 851 patients in Group A and 378 patients in Group B. Patients in Group B were smaller and younger than those in group A (median weight 3.8 vs. 4.3 kg, P < 0.001; median age 42 vs. 76 days, P = 0.02).

MEASUREMENTS AND RESULTS

Overall mortality was lower for Group B as compared to Group A (2.4% vs. 6.2%, P < 0.007). Significant reduction in mortality between Group B and Group A was noted in neonates (4.3% vs. 12%, P = 0.008) but did not reach significance in infants (0.9% vs. 2.6%, P = NS). Patients undergoing the highest-risk operations (RACHS-1 groups 5 + 6) had a 70% reduction in mortality when comparing Group B to Group A, (9% vs. 30%, P = 0.03), but no statistical difference in mortality was noted in those patients undergoing lower-risk operations (RACHS-1 groups 1 and 2, Group B 0.5% vs. Group A 1.5%, P = NS).

CONCLUSIONS

The combination of goal-directed therapy and point of care testing significantly reduced mortality in patients undergoing congenital heart surgery. This improvement is greatest in the youngest patients and those undergoing higher-risk surgeries.

Acute renal failure - definition, outcome measures, animal models, fluid therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group

INTRODUCTION

There is no consensus definition of acute renal failure (ARF) in critically ill patients. More than 30 different definitions have been used in the literature, creating much confusion and making comparisons difficult. Similarly, strong debate exists on the validity and clinical relevance of animal models of ARF; on choices of fluid management and of end-points for trials of new interventions in this field; and on how information technology can be used to assist this process. Accordingly, we sought to review the available evidence, make recommendations and delineate key questions for future studies.

METHODS

We undertook a systematic review of the literature using Medline and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated recommendations and/or directions for future research.

RESULTS

We found sufficient consensus on 47 questions to allow the development of recommendations. Importantly, we were able to develop a consensus definition for ARF. In some cases it was also possible to issue useful consensus recommendations for future investigations. We present a summary of the findings. (Full versions of the six workgroups' findings are available on the internet at http://www.ADQI.net)

CONCLUSION

Despite limited data, broad areas of consensus exist for the physiological and clinical principles needed to guide the development of consensus recommendations for defining ARF, selection of animal models, methods of monitoring fluid therapy, choice of physiological and clinical end-points for trials, and the possible role of information technology.

Increased blood lacate levels: an important warning signal in surgical practice

Both in emergency and elective surgical patients increased blood lactate levels warn the physician that the patient is at risk of increased morbidity and decreased changes of survival. Prompt therapeutic measures to restore the balance between oxygen demand and supply are warranted in these patients.

Occult hypoperfusion is associated with increased mortality in hemodynamically stable, high-risk, surgical patients

BACKGROUND

Our aim was to examine whether serial blood lactate levels could be used as predictors of outcome.

METHODS

We prospectively studied 44 high-risk, hemodynamically stable, surgical patients. Blood lactate values, mean arterial pressure, heart rate and urine output were obtained at patient admission to the study, at 12, 24 and 48 hours.

RESULTS

The nonsurvivors (n = 7) had similar blood lactate levels initially (3.1 +/- 2.3 mmol/l versus 2.2 +/- 1.0 mmol/l, P = not significant [NS]), but had higher levels after 12 hours (2.9 +/- 1.7 mmol/l versus 1.6 +/- 0.9 mmol/l, P = 0.012), after 24 hours (2.1 +/- 0.6 mmol/l versus 1.5 +/- 0.7 mmol/l, P = NS) and after 48 hours (2.7 +/- 1.8 mmol/l versus 1.9 +/- 1.4 mmol/l, P = NS) as compared with the survivors (n = 37). Arterial bicarbonate concentrations increased significantly in survivors and were higher than in nonsurvivors after 24 hours (22.9 +/- 5.2 mEq/l versus 16.7 +/- 3.9 mEq/l, P = 0.01) and after 48 hours (23.1 +/- 4.1 mEq/l versus 17.6 +/- 7.1 mEq/l, P = NS). The PaO2/FiO2 ratio was higher in survivors initially (334 +/- 121 mmHg versus 241 +/- 133 mmHg, P = 0.03) and remained elevated for 48 hours. There were no significant differences in mean arterial pressure, heart rate, and arterial blood oxygenation at any time between survivors and nonsurvivors. The intensive care unit stay (40 +/- 42 hours versus 142 +/- 143 hours, P < 0.001) and the hospital stay (12 +/- 11 days versus 24 +/- 17 days, P = 0.022) were longer for nonsurvivors than for survivors. The Simplified Acute Physiology Score II score was higher for nonsurvivors than for survivors (34 +/- 9 versus 25 +/- 14, P = NS). The urine output was slightly lower in the nonsurvivor group (P = NS). The areas under the receiving operating characteristic curves were larger for initial values of Simplified Acute Physiology Score II and blood lactate for predicting death.

CONCLUSION

Elevated blood lactate levels are associated with a higher mortality rate and postoperative complications in hemodynamically stable surgical patients.

Evaluating the reliability of automated collision notification systems

The use of an automated collision notification (ACN) device in vehicles can greatly reduce the time between crash occurrence and notification of emergency medical services (EMSs). Most ACN devices rely on cellular technology to report important crash information to the proper authorities. The objective of this study was to examine the ability of the existing western New York cellular analog system to support ACN systems. The first task was to develop a model predicting the probability of successfully completing an emergency ACN call at attenuated levels of received signal strength indicator (RSSI), a measurement of the bond between cell phone and tower. Then, empirical estimates were made of the time necessary for call completion at given levels of the RSSI. The RSSI is sampled at locations throughout Erie County, New York, and this information is used to determine the probability of successful call completion for different locations within the county. This model was then applied to historic data for selected past crashes. Finally, the findings were compared with real-world crash data obtained from the ACN Field Operational Test program, where 750 ACN devices were installed in cars and their performance examined over time. An interpolated map of the sampled RSSI values suggests that cellular coverage in Erie County is adequate to support the automated collision network technology. The models and techniques described here are applicable to other areas and regions of the country.

Tissue oxygen monitoring during hemorrhagic shock and resuscitation: a comparison of lactated Ringer's solution, hypertonic saline dextran, and HBOC-201

BACKGROUND

The ideal resuscitation fluid for the trauma patient would be readily available to prehospital personnel, universally compatible, effective when given in small volumes, and capable of reversing tissue hypoxia in critical organ beds. Recently developed hemoglobin-based oxygen-carrying solutions possess many of these properties, but their ability to restore tissue oxygen after hemorrhagic shock has not been established. We postulated that a small-volume resuscitation with HBOC-201 (Biopure) would be more effective than either lactated Ringer's (LR) solution or hypertonic saline dextran (HSD) in restoring baseline tissue oxygen tension levels in selected tissue beds after hemorrhagic shock. We further hypothesized that changes in tissue oxygen tension measurements in the deltoid muscle would reflect the changes seen in the liver and could thus be used as a monitor of splanchnic resuscitation.

METHODS

This study was a prospective, blinded, randomized resuscitation protocol using anesthetized swine (n = 30), and was modeled to approximate an urban prehospital clinical time course. After instrumentation and splenectomy, polarographic tissue oxygen probes were placed into the liver (liver PO2) and deltoid muscle (muscle PO2) for continuous tissue oxygen monitoring. Swine were hemorrhaged to a mean arterial pressure (MAP) of 40 mm Hg over 20 minutes, shock was maintained for another 20 minutes, and then 100% oxygen was administered. Animals were then randomized to receive one of three solutions: LR (12 mL/kg), HSD (4 mL/kg), or HBOC-201 (6 mL/kg). Physiologic variables were monitored continuously during all phases of the experiment and for 2 hours postresuscitation.

RESULTS

At a MAP of 40 mm Hg, tissue PO2 was 20 mm Hg or less in both the liver and muscle beds. There were no significant differences in measured liver or muscle PO2 values after resuscitation with any of the three solutions in this model of hemorrhagic shock. When comparing the hemodynamic effects of resuscitation, the cardiac output was increased from shock values in all three animal groups with resuscitation, but was significantly higher in the animals resuscitated with HSD. Similarly, MAP was increased by all solutions during resuscitation, but remained significantly below baseline except in the group of animals receiving HBOC-201 (p < 0.01). HBOC-201 was most effective in both restoring and sustaining MAP and systolic blood pressure. There was excellent correlation between liver and deltoid muscle tissue oxygen values (r = 0.8, p < 0.0001).

CONCLUSION

HBOC-201 can be administered safely in small doses and compared favorably to resuscitation with HSD and LR solution in this prehospital model of hemorrhagic shock. HBOC-201 is significantly more effective than HSD and LR solution in restoring MAP and systolic blood pressure to normal values. Deltoid muscle PO2 reflects liver PO2 and thus may serve as an index of the adequacy of resuscitation in critical tissue beds.

The role of rehydration in the prevention of fat embolism syndrome

We encountered three cases of young sportsmen developing fat embolism syndrome (FES) after sustaining isolated tibial shaft fractures whilst playing football. All fractures were treated with intra-medullary nails and all three patients were kept nil-by-mouth pre-operatively without intravenous fluids. Correction of shock is often quoted as an important factor in the prevention of FES. However, animal studies have shown that dehydration, as opposed to hypovolaemia, may also be of great importance. We therefore examined the specific gravity of the urine of 20 patients with musculoskeletal injuries sustained during sport. The mean urinary specific gravity was significantly higher than that of a control group of 10 members of staff. We emphasise the importance of adequate pre-operative rehydration, especially if injuries were sustained during heavy exercise, as this may reduce the risk of developing FES.

Young versus Old: Factors Affecting Mortality After Blunt Traumatic Injury

Advanced age predicts poor outcome after trauma. We have previously demonstrated that prolonged occult hypoperfusion (POH), defined as serum lactic acid >2.4 mmol/L persisting for >12 hours, is also associated with worse outcomes. We hypothesized that older patients—a group with potentially less physiologic reserve—would be at greater risk from POH. Prospective data from adult blunt trauma patients admitted to a surgical/trauma intensive care unit from January 1, 1998 through December 31, 1999 were analyzed. Mortality, POH, Injury Severity Score (ISS), chronic health designation (CH) from the Acute Physiology and Chronic Health Evaluation, emergency department Glasgow Coma Scale score (EDGCS), emergency department systolic blood pressure (EDSBP), and gender were compared between older (>55 years) and younger (<56 years) patients and then between nonsurvivors and survivors within age cohorts. Two hundred sixty-four patients were analyzed: 195 younger and 69 older. Mortality was 8.3 per cent (22/264). Older patients had higher mortality (20.3% vs 4.1%, P < 0.05), higher CH (42.9% ± 1.3 vs 8.4% ± 0.6), lower ISS (22.6 ± 1.5 vs 25.6 ± 0.8, P < 0.05), higher EDGCS (12.9 ± 0.5 vs 10.7 ± 0.4, P < 0.05), and higher EDSBP (141.5 ± 4.1 vs 129.3 ± 2.2). There were no differences in incidence of POH and gender. Within both age cohorts nonsurvivors had higher ISS, lower EDGCS, and higher CH. Older patients with POH had 34.6 per cent mortality as compared with 11.6 per cent for no POH ( P < 0.05). Mortality in younger patients was no different in the presence of POH, and all nonsurvivors were male. Despite lower ISS and higher EDGCS and EDSBP older patients had five times the mortality of younger patients. Age-specific mortality was influenced by POH and gender. POH was associated with higher mortality only in older patients. With less physiologic reserve older patients may not have been able to adequately compensate for POH; this emphasizes the importance of rapidly correcting serum lactic acid as an endpoint in resuscitation in this population.

Blood Transfusions Correlate with Infections in Trauma Patients in a Dose-Dependent Manner

Infections are a common and significant sequela of major traumatic injury. The objective of this study was to evaluate the relationship between infections in trauma patients and the transfusion of packed red blood cells (pRBCs) within the first 48 hours of admission. We hypothesized that transfusions of pRBCs were associated with an increased risk of infection in a dose-dependent manner. All adult patients admitted to the trauma service of a Level I trauma center from November 1996 to December 1999 were studied. Secondary analysis was performed on prospectively collected data. One thousand five hundred ninety-three consecutive patients were studied; of these 12.6 per cent developed at least one infection. The overall transfusion rate was 19.4 per cent. The infection rate in patients who received at least one transfusion was significantly higher ( P < 0.0001) at 33.0 versus 7.6 per cent in patients receiving no pRBCs. Transfusions per patient ranged from 0 to 46 units. There was a clear exponential correlation in patients receiving between 0 and 15 transfusions (R 2 = 0.757). Multivariate logistic regression, which was used to identify risk factors for the development of infection, demonstrated the odds ratio of receiving pRBCs to be 1.084, with a 95 per cent confidence interval of 1.028 to 1.142 ( P = 0.0028). In summary there is a clear dose-dependent correlation between transfusions of pRBCs and the development of infection in trauma patients. Multivariate analysis further demonstrated that pRBCs were an independent risk factor for the development of infections. Although transfusions are frequently indicated, they should be administered appropriately and with no more pRBCs than absolutely necessary.

The effect of pregnancy on the response to blood loss in a rat model

STUDY OBJECTIVES

A commonly held belief is that the blunted hemodynamic response to hemorrhage observed in pregnant women is secondary to expanded blood volume. In addition to increased blood volume, pregnancy is also a vasodilated state. Vasodilatation may have deleterious effects on the response to hemorrhage by inhibiting central blood shunting after blood loss. How these conflicting variables of increased blood volume and vasodilatation integrate into a whole body model of maternal hemorrhagic shock has yet to be studied in a controlled experiment. We tested the null hypothesis that there would be no difference in the hemodynamic and metabolic responses to hemorrhage between pregnant (PRG) and non-pregnant (NPRG) rats.

METHODS

Twenty-four adult female Sprague-Dawley rats (12 PRG and 12 NPRG) were anesthetized with Althesin via the intraperitoneal route. Femoral arteries were cannulated by cut-down. Twelve (six PRG and six NPRG) rats underwent controlled catheter hemorrhage of 25% of their total blood volume. Twelve rats (six PRG and six NPRG) served as non-hemorrhage controls. Mean arterial pressure (MAP) and base excess (BE) were measured pre-hemorrhage and then every 15 min post-hemorrhage for the next 90 min. Data were reported as mean+/-standard error of the mean (S.E.M.) over the 90-min post-hemorrhage observation period. Group comparisons were analyzed by ANOVA with repeated values post-hoc by Bonferroni. Statistical significance was defined by an alpha=0.05.

RESULTS

PRG and NPRG rats were evenly matched for MAP (P=0.788) and BE (P=0.146) pre-hemorrhage. Post-hemorrhage there were no mortalities in either group. Post-hemorrhage both the PRG and NPRG groups experienced significant (P=0.011) drops in systolic and diastolic blood pressures as compared to their non-hemorrhage controls. Post-hemorrhage there was no significant (P=0.43) difference in MAP between the PRG (89+/-2 mmHg) and NPRG (80+/-2 mmHg) rats. BE also dropped significantly within both PRG (P=0.004) and NPRG (P=0.001) groups post-hemorrhage. No significant (P=0.672) difference was noted in BE between PRG and NPRG groups post-hemorrhage -6.1+/-0.3 mEq/l and -6.9+/-0.4 mEq/l, respectively.

CONCLUSION

After a controlled hemorrhage of 25% of total blood volume we found no significant differences in MAP and BE between pregnant and non-pregnant rats. Pregnancy does not affect the response to hemorrhage.

Pyruvate improves cerebral metabolism during hemorrhagic shock

Pyruvate (PYR) improves cellular and organ function hypoxia and ischemia by stabilizing the reduced nicotinamide adenine dinucleotide redox state and cytosolic ATP phosphorylation potential. In this in vivo study, we evaluated the effects of intravenous pyruvate on neocortical function, indexes of the cytosolic redox state, cellular energy state, and ischemia during a prolonged (4 h) controlled arterial hemorrhage (40 mmHg) in swine. Thirty minutes after the onset of hemorrhagic shock, sodium PYR (n = 8) was infused (0.5 g x kg(-1) x h(-1)) to attain arterial levels of 5 mM. The volume and osmotic effects were matched with 10% NaCl [hypertonic saline (HTS)] (n = 8) or 0.9% NaCl [normal saline (NS)] (n = 8). During the hemorrhage protocol, the time to peak hemorrhage volume was significantly delayed in the PYR group compared with the HTS and NS groups (94 +/- 5 vs. 73 +/- 6 and 72 +/- 4 min, P < 0.05). In addition to the early onset of the decompensatory phase of hemorrhagic shock, the complete return of the hemorrhage volume during decompensatory shock resulted in the death of five and four animals, respectively, in the HTS and NS groups. In contrast, in the PYR group, reinfusion of the hemorrhage volume was slower and all animals survived the 4-h hemorrhage protocol. During hemorrhage, the PYR group also exhibited improved cerebral cortical metabolic and function status. PYR slowed and reduced the rise in neocortical microdialysis levels of adenosine, inosine, and hypoxanthine and delayed the loss of cerebral cortical biopsy ATP and phosphocreatine content. This improvement in energetic status was evident in the improved preservation of the electrocorticogram in the PYR group. PYR also prevented the eightfold increase in the excitotoxic amino acid glutamate observed in the HTS group. The findings show that PYR administered after the onset of hemorrhagic shock markedly improves cerebral metabolic and functional status for at least 4 h.

Start with a subjective assessment of skin temperature to identify hypoperfusion in intensive care unit patients

OBJECTIVE

To determine whether physical examination alone or in combination with biochemical markers can accurately diagnose hypoperfusion.

METHODS

Data from 264 consecutive surgical intensive care unit patients were collected by two intensivists and included extremity temperature, vital signs, arterial lactate, arterial blood gases, hemoglobin, and pulmonary artery catheter values with derived indices. Days of data were divided into data collected from patients with cool extremities (cool skin temperature [CST] group) versus warm extremities (warm skin temperature [WST] group). Values are means +/- SD. Comparisons between groups were made by two-tailed unpaired t test; significance was assumed for p < or = 0.05.

RESULTS

There were 328 days of observations in the CST group versus 439 in the WST group. There were no differences (p > 0.05) between CST and WST data with regard to heart rate (107 +/- 14 vs. 99 +/- 19 beats/min), systolic blood pressure (118 +/- 24 vs. 127 +/- 28 mm Hg), diastolic blood pressure (57 +/- 14 vs. 62 +/- 15 mm Hg), pulmonary artery occlusion pressure (14 +/- 6 vs. 16 +/- 5 mm Hg), Fio2 (0.48 +/- 0.7 vs. 0.45 +/- 0.2), hemoglobin (8.8 +/- 1.6 vs. 9.3 +/- 1.3 g/dL), Pco2 (44.3 +/- 11.8 vs. 40.7 +/- 9.2 mm Hg), or Po2 (96.4 +/- 12.6 vs. 103.8 +/- 22.2 mm Hg). However, cardiac output (5.3 +/- 2.2 vs. 8.2 +/- 2.6 L/min), cardiac index (2.9 +/- 1.2 vs. 4.3 +/- 1.2 L/min/m2), pH (7.32 +/- 0.2 vs. 7.39 +/- 0.07), TCO2 (19.5 +/- 3.1 vs. 25.1 +/- 4.8 mEq/L), and Svo2 (60.2 +/- 4.4% vs. 68.2 +/- 7.8%) were all significantly lower (p < 0.05) in CST patients compared with WST patients. By comparison, lactate (4.7 +/- 1.5 vs. 2.2 +/- 1.6 mmol/L, p < 0.05) was significantly elevated in patients with cool extremities.

CONCLUSION

Combining physical examination with serum bicarbonate and arterial lactate identifies patients with hypoperfusion as defined by low Svo2 and cardiac index. Hypoperfusion may occur despite supranormal cardiac indices. Patients with cool extremities and elevated lactate levels may benefit from a pulmonary artery catheter to guide but not initiate therapy.

Resuscitation from traumatic shock

Shock is the body's response to decreased cellular perfusion. It can begin with hemorrhage, mechanical obstruction of the circulation, cardiac dysfunction, central nervous system injury, or sepsis. Once triggered, shock is perpetuated by the release of toxic compounds from ischemic cells. The treatment of shock consists of the removal or correction of the triggering pathology, followed by resuscitation back to the normal state. Clinical research in shock resuscitation in the past year has focused on recognizing the presence of shock in patients at risk, particularly those with normal vital signs but ongoing, occult hypoperfusion. In the laboratory, the emphasis has been on minimizing the initial hemorrhagic insult, minimizing the release of toxins from ischemic cells, and blocking the response to the toxins that are released.

Fluid resuscitation for the trauma patient

Attempts at prehospital fluid replacement should not delay the patient's transfer to hospital. Before bleeding has been stopped, a strategy of controlled fluid resuscitation should be adopted. Thus, the risk of organ ischaemia is balanced against the possibility of provoking more bleeding with fluids. Once haemorrhage is controlled, normovolaemia should be restored and fluid resuscitation targeted against conventional endpoints, the base deficit, and plasma lactate. Initially, the precise fluid used is probably not important, as long as an appropriate volume is given; anaemia is much better tolerated than hypovolaemia. Colloids vary substantially in their pharmacology and pharmacokinetics and the experimental findings from one cannot be extrapolated reliably to another. We still lack reliable data to prove that any of the colloids reduce mortality in trauma patients. In the presence of SIRS, hydroxyethyl starch may reduce capillary leak. Hypertonic saline solutions may have some benefit in patients with head injuries although this has yet to be proven beyond doubt. It is likely that one or more of the haemoglobin-based oxygen carriers currently under development will prove to be valuable in the treatment of the trauma patient.

Critical care in the emergency department: A physiologic assessment and outcome evaluation

OBJECTIVES

The changing landscape of health care in this country has seen an increase in the delivery of care to critically ill patients in the emergency department (ED). However, methodologies to assess care and outcomes similar to those used in the intensive care unit (ICU) are currently lacking in this setting. This study examined the impact of ED intervention on morbidity and mortality using the Acute Physiology and Chronic Health Evaluation (APACHE II), the Simplified Acute Physiology Score (SAPS II), and the Multiple Organ Dysfunction Score (MODS).

METHODS

This was a prospective, observational cohort study over a three-month period. Critically ill adult patients presenting to a large urban ED and requiring ICU admission were enrolled. APACHE II, SAPS II, and MODS scores and predicted mortality were obtained at ED admission, ED discharge, and 24, 48, and 72 hours in the ICU. In-hospital mortality was recorded.

RESULTS

Eighty-one patients aged 64 +/- 18 years were enrolled during the study period, with a 30.9% in-hospital mortality. The ED length of stay was 5.9 +/- 2.7 hours and the hospital length of stay was 12.2 +/- 16.6 days. Nine (11.1%) patients initially accepted for ICU admission were later admitted to the general ward after ED intervention. Septic shock was the predominant admitting diagnosis. At ED admission, there was a significantly higher APACHE II score in nonsurvivors (23.0 +/- 6.0) vs survivors (19.8 +/- 6.5, p = 0.04), while there was no significant difference in SAPS II or MODS scores. The APACHE II, SAPS II, and MODS scores were significantly lower in survivors than nonsurvivors throughout the hospital stay (p </= 0.001). The hourly rates of change (decreases) in APACHE II, SAPS II, and MODS scores were significantly greater during the ED stay (-0.55 +/- 0.64, -1.02 +/- 1.10, and -0.16 +/- 0.43, respectively) than subsequent periods of hospitalization in survivors (p < 0.05). There was a significant decrease in APACHE II and SAPS II predicted mortality during the ED stay (-8.0 +/- 14.0% and -6.0 +/- 14.0%, respectively, p < 0.001) and equally at 24 hours in the ICU (-7.0 +/- 13.0% and -4.0 +/- 16.0%, respectively, p </= 0.02). The APACHE II and SAPS II predicted mortality approached actual in-hospital mortality at approximately 12 hours and 36 hours after ED admission (in the ICU), respectively.

CONCLUSIONS

The care provided during the ED stay for critically ill patients significantly impacts the progression of organ failure and mortality. Although this period is brief compared with the total length of hospitalization, physiologic determinants of outcome may be established before ICU admission. This study emphasizes the importance of ED intervention. It also suggests that unique physiologic assessment methodologies should be developed to examine the quality of patient care, improve the accuracy of prognostic decisions, and objectively measure the impact of clinical interventions and pathways in the ED setting.

Y. A Successful Multitnodality Strategy for Management of Liver Injuries

The treatment of liver injuries involves many strategies ranging from observation to operative intervention and includes numerous options such as angiography, packing, and damage-control procedures. In July 1994 we instituted a protocol for the management of traumatic liver injuries. The main objective of this study was to evaluate the management of liver injuries occurring since the institution of the protocol. Two hundred three consecutive adult patients with liver injuries were evaluated at our Level I trauma center between July 1994 and May 1999. Eighty-eight per cent of the injuries were blunt with a mean Injury Severity Score (ISS) of 24.3 ± 0.8 and a survival probability (Ps) of 90.0 ± 1.5 per cent. The overall mortality was 6.4 per cent. A comparison between patients with minor liver injuries and patients with more severe injuries [Abbreviated Injury Score (AIS) <3 vs >3] demonstrated no difference in mortality between the two groups despite a Ps of 93.8 ± 1.3 per cent in patients with an AIS <3 versus 84.1 ± 3.3 per cent in patients with an AIS >3. The most common complication in our patient population was posthemorrhagic anemia, which was seen in 10.8 per cent of cases. Severity of injury did not result in a significant difference in the complication rate. Patients who underwent laparotomy had a statistically higher ISS, a lower Ps, and a mortality rate of 11.5 per cent compared with 3.7 per cent ( P = 0.03) in patients managed nonoperatively. However, a comparison of patients undergoing laparotomy with those who did not and who had equivalent ISS demonstrated no difference in mortality. Our results demonstrated that a preplanned management strategy was a successful way in which to treat patients with traumatic liver injuries. Although nonoperative management of liver injuries has been common practice a management plan that involves a multimodal surgical strategy is essential.

Hemorrhage and resuscitation induce delayed inflammation and pulmonary dysfunction in mice

BACKGROUND

It is well known that hemorrhagic shock induces inflammatory changes. Our objective was to study the histologic and biochemical changes in the lung and evaluate alterations in respiratory function after hemorrhage and resuscitation (H/R) in mice.

METHODS

After 30 min of hemorrhagic shock, mice were resuscitated with shed blood to restore mean arterial blood pressure to baseline. A sham group was anesthetized and instrumented for 30 min, but did not undergo hemorrhage. Myeloperoxidase (MPO) levels were measured and histologic analysis was performed on lung tissue. Pulmonary function was evaluated using whole-body plethysmography (WBP) 1, 3, and 5 days postprocedure. Alveolar function was evaluated by measuring carbon monoxide uptake via gas chromatography 5 days after H/R.

RESULTS

Five days after H/R, mice exposed to shock had significantly higher lung MPO levels and showed greater histologic evidence of lung injury. Airway resistance (Penh) in the sham mice was 0.91 +/- 0.06 versus 1.21 +/- 0.09 in the hemorrhage group (P < 0.01). Alveolar function was significantly decreased in the H/R group (70.8 +/- 3.6%) compared with shams (81.6 +/- 1.8%) (P < 0.05).

CONCLUSIONS

Hemorrhage and resuscitation cause delayed biochemical, histologic, and physiologic changes in the lung. These were marked by increased lung MPO, increased neutrophils, and decreased alveolar function. The alterations of pulmonary function and structure were most severe 5 days after H/R.

Occult hypoperfusion is associated with increased morbidity in patients undergoing early femur fracture fixation

BACKGROUND

The presence of persistent occult hypoperfusion (OH) is associated with higher morbidity and mortality rates after trauma. Early femur fracture fixation in trauma patients with multiple injuries is associated with decreased morbidity and mortality. Association of OH and incidence of postoperative complications after intramedullary (IM) fixation in patients with femur fractures was investigated.

METHODS

A retrospective study design was used. All patients with femur fractures admitted to the trauma service of a Level I trauma center between January 1, 1995, and August 1, 1998, who were older than 18 years of age and who had IM fracture fixation within 24 hours of admission and serum lactate determinations on admission and at proscribed intervals, were included in the study. Patients with lactic acid levels > or = 2.5 mmol/L were determined to have OH. No patients had clinical signs of shock (hypotension, tachycardia, decreased urine output) on transfer to the operating room. Complete resuscitation was defined as a lactic acid level < 2.5 mmol/L. Patients were divided into two groups based on presence/absence of OH determined from the lactic acid level immediately before surgery. The incidence of all postoperative organ complications was recorded, and complication rates were compared between groups. Total hospital costs were also compared.

RESULTS

One hundred seventy-seven patients with femur fractures were admitted to the trauma service during this period. Seventy-nine patients met initial criteria for inclusion in the study. Further review excluded 32 patients. Occult hypoperfusion was present in 20 patients before early IM fixation (group 2). Twenty-seven patients were completely resuscitated before early IM fixation (group 1). Injury Severity Scores were similar in both groups. Group 2 had 35 complications in 20 patients, and group 1 had 11 complications in 27 patients. A significant difference was found in incidence of postoperative complications in group 1 (20%) versus group 2 (50%). Group 2 also had a significantly higher proportion of postoperative infections than group 1 (72% vs. 28%, respectively) and higher total hospital costs ($46,469 vs. $23,139).

CONCLUSION

The presence of OH in trauma patients undergoing early IM fixation of a femur fracture is associated with a twofold higher incidence of postoperative complications. Clinical judgment, not surgical dogma, should guide the timing of IM fixation in these patients. Identifying and correcting OH through relatively simple resuscitative measures may be advantageous in reducing morbidity in the patient with multiple injuries.