Fluid Resuscitation in Traumatic Hemorrhagic Shock

Flat Inferior Vena Cava: Indicator of Poor Prognosis in Trauma and Acute Care Surgery Patients

Flat inferior vena cava (IVC) on ultrasound examination has been shown to correlate with hypovolemic status. We hypothesize that a flat IVC on limited echocardiogram (LTTE) performed in the emergency room (ER) correlates with poor prognosis in acutely ill surgical patients. We conducted a retrospective review of all patients undergoing LTTE in the ER from September 2010 until June 2011. IVC diameter was estimated by subxiphoid window. Flat IVC was defined as diameter less than 2 cm. Fat IVC was defined as diameter greater than 2 cm. Need for intensive care unit admission, blood transfusion requirement, mortality, and need for emergent operation between patients with flat versus Fat IVC were compared. One hundred one hypotensive patients had LTTE performed in the ER. Average age was 38 years. Admission diagnosis was blunt trauma (n = 80), penetrating trauma (n = 13), acute care surgery pathology (n = 7), and burn (n = 1). Seventy-four patients had flat IVC on initial LTTE. Compared with those with fat IVC, flat patients were found have higher rates of intensive care unit admission (51.3 vs 14.8%; P = 0.001), blood transfusion requirement (12.2 vs 3.7%), and mortality (13.5 vs 3.7%). This population also underwent emergent surgery on hospital Day 1 more often (16.2 vs 0%; P = 0.033). Initial flat IVC on LTTE is an indicator of hypovolemia and a predictor of poor outcome.

No. 115-Hemorrhagic Shock

OBJECTIVE

To review the clinical aspects of hemorrhagic shock and provide recommendations for therapy.

OPTIONS

Early recognition of hemorrhagic shock and prompt systematic intervention will help avoid poor outcomes.

OUTCOMES

Establish guidelines to assist in early recognition of hemorrhagic shock and to conduct resuscitation in an organized and evidence-based manner.

EVIDENCE

Medline references were sought using the MeSH term "hemorrhagic shock." All articles published in the disciplines of obstetrics and gynaecology, surgery, trauma, critical care, anesthesia, pharmacology, and hemotology between 1 January 1990 and 31 August 2000 were reviewed, as well as core textbooks from these fields. Selected references from these articles and book chapters were also obtained and reviewed. The level of evidence has been determined using the criteria described by the Canadian Task Force on Preventive Health Care.

VALIDATION

These guidelines have been reviewed by the Clinical Practice Obstetrics Committee and approved by Executive and Council of the Society of Obstetricians and Gynaecologists of Canada.

SPONSORS

The Society of Obstetricians and Gynaecologists of Canada.

RECOMMENDATIONS

Fluid Resuscitation in Tactical Combat Casualty Care: Yesterday and Today

The prevailing wisdom for the prehospital fluid resuscitation of trauma victims in hemorrhagic shock in 1992 was to administer 2 L of crystalloid solution as rapidly as possible. A review of the fluid resuscitation literature found that this recommendation was not well supported by the evidence at the time. Prehospital fluid resuscitation strategies were reevaluated in the 1993-1996 Tactical Combat Casualty Care (TCCC) research program. This article reviews the advances in prehospital fluid resuscitation as recommended by the original TCCC Guidelines and modified over the following 2 decades. These advances include hypotensive resuscitation, use of prehospital whole blood or blood components when feasible, and use of Hextend or selected crystalloids when logistical considerations make blood or blood component use not feasible.

Sonographic assessment of volaemia: development and validation of a new method in dogs

OBJECTIVES

The aims of this study were to describe a method for the sonographic assessment of volaemia, to determinate inter- and intra-operator variability and to assess the ability to detect blood loss after blood donation in healthy dogs.

MATERIALS AND METHODS

The left kidney was identified in a spleno-renal view, and transverse views of the caudal vena cava and aorta were obtained in 12 dogs. Vessel diameters were measured in B-mode, in duplicate by two operators, and the caudal vena cava:aorta ratio was calculated. Intra- and inter-operator variabilities were assessed using a Bland-Altman method by plotting the differences between the repeated measurements obtained from the same subject by the same operator and by the two operators against their means. Before and after blood donation measurements were compared using paired t-tests or one-sample t-tests, if appropriate.

RESULTS

Intra- and inter-operator variability was within the limit of agreement for the vast majority of measurements. After a blood donation of 9·8 ±2·2 mL/kg, the mean aorta measurements were not significantly different from those obtained before blood donation (1·11 versus 1·10, P=0·28), whereas the mean caudal vena cava measurements and caudal vena cava:aorta ratios were significantly lower (1·28 versus 1·01, P<0·0001; 1·17 versus 1·01, P=0·0001, respectively).

CLINICAL SIGNIFICANCE

The low intra- and inter-operator variabilities in the caudal vena cava, aorta and caudal vena cava:aorta ratio measurements support their reliability and operator independency. The sonographic assessment of volaemia appears to be a promising non-invasive, repeatable point-of-care ultrasound protocol for assessment and monitoring of blood loss. Further studies are needed to assess the sonographic assessment of volaemia protocol in spontaneously bleeding dogs.

Correlation of the ratio of caudal vena cava diameter and aorta diameter with systolic pressure variation in anesthetized dogs

OBJECTIVE

To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV).

ANIMALS

14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds.

PROCEDURES

Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed.

RESULTS

28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV.

The clinical and economic burden of significant bleeding during lung resection surgery: A retrospective matched cohort analysis of real-world data

OBJECTIVES

The objective of this retrospective study was to quantify the clinical and economic burden of significant bleeding in lung resection surgery in the US.

METHODS

This study utilized 2009-2012 data from the Premier Perspective Database^TM. Adult patients with primary pulmonary lobectomy or segmentectomy procedures were categorized by the surgical approach (VATS vs open) and primary diagnosis (primary or metastatic lung cancer vs non-lung cancer). Patients requiring ≥3 units of blood products with at least 1 unit of PRBCs: "significant bleeding" cohort; those requiring <3 units: "non-significant bleeding" cohort; and those not requiring blood products: "no bleeding" cohort. A matched cohort analysis was performed between the "significant bleeding" and the "no bleeding cohort" using matching variables: hospital, lung cancer diagnosis, year of surgery, APR-DRG severity score, procedure type and approach, age, and gender.

RESULTS

The "All-patient" cohort comprised 21,429 patients: 213 "significant bleeding"; 2,780 "non-significant bleeding"; and 18,436 "no bleeding". Overall incidence of significant chest bleeding was 0.99%. Patients from "significant bleeding" cohort and "non-significant bleeding" cohort had 2.5 days and 2 days (p < 0.0001) longer length of stay in the hospital compared to those in the "no bleeding" cohort, respectively. Overall, hospital costs for "significant bleeding" cohort were higher than "no bleeding" cohort for those who were covered under Medicare ($59,871 vs $23,641), were ≥76 years of age ($64,010 vs $24,243), had greater severity of illness ($97,813 vs $51,871) and underwent open segmentectomy ($74,220 vs $21,903). Hospital costs for "significant bleeding" cohort and "non-significant bleeding" were significantly higher ($11,589 and $5,280, respectively, p < 0.0001) than no bleeding cohort.

CONCLUSIONS

Although significant bleeding during lung resection surgery is rare, patients with such complication could stay longer at the hospital and cost an average of $13,103 more than those without.

Life-threatening airway obstruction due to upper airway edema and marked neck swelling after labor and delivery

BACKGROUND AND OBJECTIVES

Airway changes generally occur in normal gravidas; however, these changes could cause critical situations in specific populations.

OBJECTIVES

This article presents the case of a difficult airway patient that went into shock because of atonic bleeding after vaginal delivery for stillbirth.

CASE REPORT

A 32-yr-old woman with atonic bleeding after vaginal delivery for stillbirth was transferred to our hospital. She manifested shock, and her respiratory condition was progressively deteriorating. Airway obstruction caused by neck swelling and pharyngolaryngeal edema was apparent. We tried tracheal intubation using direct and indirect laryngoscopes. However, it turned out that insertion of the laryngoscopic devices to the oral cavity was impossible. After several attempts using the Trachlight™, successful intubation was finally made. After hysterectomy, she was admitted to the intensive care unit (ICU) and treated for five days. At discharge from the ICU, her Mallampati score was I-II. Her body weight decreased 60 kg to 51 kg during ICU stay.

CONCLUSIONS

We believe that concomitant attacks of labor and delivery and fluid resuscitation probably worsened upper airway and neck edema enough to cause acute airway obstruction and difficult laryngoscopy.

Terlipressin with limited fluid resuscitation in a swine model of hemorrhage

BACKGROUND

Principles of damage control resuscitation include minimizing intravenous fluid (IVF) administration while correcting perfusion pressure as quickly as possible. Recent studies have identified a potential advantage of vasopressin over catecholamines in traumatic shock. Terlipressin (TP) is a vasopressin analogue used to reverse certain shock etiologies in some European countries.

STUDY OBJECTIVE

We evaluated three dosages of TP when combined with a limited colloid resuscitation strategy on mean arterial pressure (MAP) and lactatemia in a swine model of isolated hemorrhage.

METHODS

Sixty anesthetized swine underwent intubation and severe hemorrhage. Subjects were randomized to one of four resuscitation groups: 4 mL/kg Hextend(®) (Hospira Inc, Lake Forest, IL) only, 3.75 μg/kg TP + Hextend, 7.5 μg/kg TP + Hextend, or 15 μg/kg TP + Hextend. MAP and heart rate were recorded every 5 min. Baseline and serial lactate values at 30-min intervals were recorded and compared.

RESULTS

Subjects receiving 7.5 μg/kg TP had significantly higher MAPs at times t15 (p = 0.012), t20 (p = 0.004), t25 (p = 0.018), t30 (p = 0.032), t35 (p = 0.030), and t40 (p = 0.021). No statistically significant differences in lactate values between TP groups and controls were observed.

CONCLUSION

Subjects receiving 7.5 μg/kg of TP demonstrated improved MAP within 10 min of administration. When combined with minimal IVF resuscitation, TP doses between 3.75 and 15 μg/kg do not elevate lactate levels in hemorrhaged swine.

Towards hemostatic resuscitation: the changing understanding of acute traumatic biology, massive bleeding, and damage-control resuscitation

During the past decade there has been a profound change in the understanding of postinjury coagulation. Concurrently, new data suggest that a resuscitative strategy to minimize large volumes of crystalloid while recreating whole is associated with reduced morbidity and mortality. This article outlines the history of resuscitation and transfusion practices in trauma, the changing understanding of coagulation and inflammation, and clinical data driving changes in resuscitative conduct. Finally, the current state of the science suggests future basic science and clinical investigation that will drive changes in transfusion and resuscitation in severely injured military personnel and civilian patients.

A Safety Assessment of Diaspirin Cross-Linked Hemoglobin (DCLHb) in the Treatment of Hemorrhagic, Hypovolemic Shock

Objective:

To determine the safety and possible efficacy of diaspirin cross-linked hemoglobin (DCLHb) in the treatment of patients in Class II–IV hemorrhagic, hypovolemic shock.

Design:

Multicenter, randomized, normal saline-controlled, dose-escalation study.

Setting:

Eleven hospitals in the U.S. and Belgium.

Subjects:

One hundred and thirty-nine (139) hospitalized patients with Class II–IV hemorrhagic, hypovolemic shock within the previous 4 hours who still were requiring therapy for shock.

Interventions:

Beginning with the lowest dose, patients were randomized to receive 50,100, or 200 mL of either 10% DCLHb or normal saline infused intravenously over 15 minutes. Following infusion of either treatment, further fluid resuscitation could be given, as necessary, to maintain perfusion. Vital signs, laboratory assessments, blood and fluid administration, complications, and adverse events were recorded at various times from the end of infusion through 72 hours after infusion.

Results:

A total of 29 (13 DCLHb- and 16 saline-treated) patients died during the study period. Adverse events were experienced by 61% of patients in the DCLHb group and 53% of patients in the saline group; serious adverse events occurred in 28% of DCLHb-treated patients and 30% of saline-treated patients. The incidence of prospectively defined, clinical complications, including renal insufficiency and renal failure, was similar between the treatment groups except for the occurrence of dysrhythmias/conduction disorders, which occurred significantly more frequently in the saline-treated patients than the DCLHb-treated patients (p = 0.041). At the highest dose level (200 mL), statistically significant between-group differences were observed with greater increases in serum amylase, LDH, the isoenzymes LD1,2,4 and 5, and CK-MB in the DCLHb group compared to the control group; none were of clinical significance. The volume of blood administered did not differ between the groups. Overall 24- and 72-hour survival rates were similar between treatment groups, although the hospital discharge rate was slightly higher in the DCLHb-treated patients (80%) compared with the saline-treated patients (74%).

Conclusion:

Administration of 50 to 200 mL of DCLHb to patients in hemorrhagic, hypovolemic shock was not associated with evidence of end organ toxuity or significant adverse events. Further studies involving larger doses and, perhaps, earlier administration of DCLHb are warranted.

Does CT evidence of a flat inferior vena cava indicate hypovolemia in blunt trauma patients with solid organ injuries?

BACKGROUND

Nonoperative management for selective patients with solid organ injuries from blunt trauma has gained wide acceptance. However, for trauma surgeons, it is often difficult to estimate a patient's circulatory volume. Some authors have proposed that the presence of a collapsed inferior vena cava (IVC) on computed tomography (CT) scan correlates with inadequate circulatory volume. Our aim was to verify whether CT evidence of a flat IVC (FI) is an indicator of hypovolemia in blunt trauma patients with solid organ injuries.

METHODS

We conducted a retrospective chart review of all blunt trauma patients with solid organ injuries admitted to our Medical Center from July 2003 to September 2006. Of the 226 patients reviewed, 29 had CT evidence of FI. We compared Injury Severity Scores, hemodynamic parameters, fluid and blood transfusion requirements, mortality rate, and hospital course between patients with (FI group) and without FI (non-FI [NFI] group).

RESULTS

The FI group had higher rates of intensive care unit admission and mortality, in addition to longer intensive care unit stays, when compared with the NFI group. In addition, the patients in the FI group needed larger amounts of fluid and blood transfusions and presented lower hemoglobin levels during the first week of admission; furthermore, the majority deteriorated to a state of shock in the emergency department.

CONCLUSIONS

CT evidence of FI is a good indicator of hypovolemia and an accurate predictor for prognosis in trauma patients with blunt solid organ injuries.

Evaluation and management of shock States: hypovolemic, distributive, and cardiogenic shock

Shock states have multiple etiologies, but all result in hypoperfusion to vital organs, which can lead to organ failure and death if not quickly and appropriately managed. Pharmacists should be familiar with cardiogenic, distributive, and hypovolemic shock and should be involved in providing safe and effective medical therapies. An accurate diagnosis is necessary to initiate appropriate lifesaving interventions and target therapeutic goals specific to the type of shock. Clinical signs and symptoms, as well as hemodynamic data, help with initial assessment and continued monitoring to provide adequate support for the patient. It is necessary to understand these hemodynamic parameters, medication mechanisms of action, and available mechanical support when developing a patient-specific treatment plan. Rapid therapeutic intervention has been proven to decrease morbidity and mortality and is crucial to providing the best patient outcomes. Pharmacists can provide their expertise in medication selection, titration, monitoring, and dose adjustment in these critically ill patients. This review will focus on parameters used to assess hemodynamic status, the major causes of shock, pathophysiologic factors that cause shock, and therapeutic interventions that should be employed to improve patient outcomes.

Hemorrhagic shock and nitric oxide release from erythrocytic nitric oxide synthase: a quantitative analysis

A large loss of blood during hemorrhage can result in profound shock, a state of hypotension associated with hemodynamic abnormalities. One of the hypotheses to account for this collapse of homeostasis is that the production of nitric oxide (NO), a gas molecule that dilates blood vessels, is significantly impaired during hemorrhage, resulting in a mismatch between O(2) delivery and the metabolic activity in the tissues. NO can be released from multiple sources in the vasculature. Recent studies have shown that erythrocytes express functional endothelial nitric oxide synthase (NOS3), which potentially serves as an intraluminal NO source. NO delivery from this source is complex: erythrocytes are not only NO producers but also act as potent sinks because of the high affinity of NO for hemoglobin. To test our hypothesis that the loss of erythrocytic NOS3 during hemorrhage contributes to NO deficiency-related shock, we have constructed a multicellular computational model that simulates NO production and transport to allow us to quantify the loss of NO under different hemorrhagic conditions. Our model shows that: (1) during mild hemorrhage and subsequent hemodilution (hematocrit >30%), NO from this intraluminal source is only slightly decreased in the vascular smooth muscle, but the NO level is significantly reduced under severe hemorrhagic conditions (hematocrit <30%); (2) whether a significant amount of NO from this source can be delivered to vascular smooth muscle is strongly dependent on the existence of a protective mechanism for NO delivery; (3) if the expression level of NOS3 on erythrocytes is similar to that on endothelial cells, we estimate approximately 13 pM NO at the vascular smooth muscle from this source when such a protective mechanism is involved. This study provides a basis for detailed studies to characterize the impairment of NO release pathways during hemorrhage and yield important insights for the development of resuscitation methods.

Investigation of the cause of readmission to the intensive care unit for patients with lung edema or atelectasis

PURPOSE

For patients with acute respiratory failure due to lung edema or atelectasis, Surplus lung water that is not removed during an initial stay in the Intensive Care Unit (ICU) may be related to early ICU readmission. Therefore, we performed a retrospective study of patient management during the first ICU stay for such patients.

MATERIALS AND METHODS

Of 1,835 patients who were admitted to the ICU in the 36 months from January, 2003 to December, 2005, 141 were patients readmitted, and the reason for readmission was lung edema or atelectasis in 21 patients. For these 21 patients, correlations were investigated between body weight gain at the time of initial ICU discharge (weight upon discharge from the ICU / weight when entering the ICU) and the time to ICU readmission, between body weight gain and the P/F ratio at ICU readmission, between the R/E ratio (the period using a respirator (R) / the length of the ICU stay after extubation (E)) and the time to ICU readmission, between the R/E ratio and body weight gain, and between body weight gain until extubation and the time to extubation.

RESULTS

A negative linear relationship was found between body weight gain at the time of initial ICU discharge and the time to ICU readmission, and between body weight gain at the time of ICU discharge and the P/F ratio at ICU readmission. If body weight had increased by more than 10% at ICU discharge or the P/F ratio was below 150, readmission to the ICU within three days was likely. Patients with a large R/E ratio, a large body weight gain, and a worsening P/F ratio immediately after ICU discharge were likely to be readmitted soon to the ICU. Loss of body weight during the period of respirator support led to early extubation, since a positive correlation was found between the time to extubation and body weight gain.

CONCLUSION

Fluid management failure during the first ICU stay might cause ICU readmission for patients who had lung edema or atelectasis. Therefore, a key to the prevention of ICU readmission is to ensure complete recovery from lung failure before the initial ICU discharge. Strict water management is crucial based on body weight measurement and removal of excess lung water is essential. In addition, an apparent improvement in respiratory state may be due to respiratory support, and such an improvement should be viewed cautiously. Loss of weight at the refilling stage of transfusion prevents ICU readmission and may decrease the length of the ICU stay.

The Effect of Aprotinin on Brain Ischemic-Reperfusion Injury After Hemorrhagic Shock in Rats: An Experimental Study

BACKGROUND

We aimed to demonstrate the positive effects of the serine protease inhibitor aprotinin on neural ischemia-reperfusion injury and apoptosis in a rat model.

METHODS

There were 18 rats divided into 3 groups: group A (sham, n = 6), group B (ischemia-reperfusion, n = 6), and group C (ischemia-reperfusion + aprotinin, n = 6). The systolic blood pressure of the group B and C rats was decreased to 40% to 50% of the normal level by taking blood from the femoral vein to develop hemorrhagic shock. The blood was retained and given to the remaining group B and C rats for reperfusion 20 minutes after the procedure. In group B, isotonic solution and, in group C, aprotinin was administered to the rats 5 minutes before reperfusion. After the rats were killed, the brain tissue samples were fixed for histopathologic examination. Brain tissue superoxide dismutase, malondialdehyde, and tissue myeloperoxidase level and apoptotic cell analyses were performed in all groups.

RESULTS

Superoxide dismutase level decreased from group A to group B and increased from group B to group C (p < 0.05). Malondialdehyde and myeloperoxidase levels and apoptotic cells increased from group A to group B and decreased from group B to group C (p < 0.05).

CONCLUSION

The results suggest that the systemic use of aprotinin in ischemic neural tissue prevents reperfusion injury and also protects the morphologic, functional, and biochemical integrity of the neural tissue.

The Evaluation of Protective Effects of FK-506 on Neural Ischemic-Reperfusion Injury: an Experimental Study

OBJECTIVE

In this study, we aimed to delineate the mode of neuroprotective action of FK-506, and demonstrated that FK-506 could decrease oxidative stress and apoptotic cell death in an in vivo rat model of neural ischemia-reperfusion after hemorrhagic shock.

METHODS

Thirty rats were used as experimental subjects and divided into five equal groups. Group A rats (sham group, n = 6) were anesthetized and craniotomies were performed for collecting brain tissue samples. In group B ischemia-reperfusion (I/R + 1 h, n = 6), group C (I/R + 24 h, n = 6), group D (I/ R + 1 h FK-506, n = 6) and group E (I/R + 24 h FK-506, n = 6), systolic blood pressure of the rats decreased to 40-50% of the normal level via bleeding from the femoral vein. Thus, a hemorrhagic shock and ischemic neural tissue model was formed. The bloodwas retained and given to the remaining animals in groups B, C,Dand E via femoral vein for reperfusion 20 min after the procedure. In group D and E, 1 mg/kg FK-506 in 0.5 ml isotonic solution was administered to the rats 5 min before reperfusion. Group B and D rats were sacrificed after 1 h and group Cand E rats were sacrificed 24 h after reperfusion; the rats were sacrificed via bleeding associated with intracardiac puncture. Craniotomy was also performed in groups B, C, D and E and brain tissue samples were fixed using neutral buffered 10% formaldehyde solution for immunohistopathological examination as in group A. Brain tissue superoxide dismutase (SOD) activities, malondialdehyde (MDA) levels, tissue myeloperoxydase (MPO) activities and apoptotic cell analyses with Apo 2.7 immunohistochemically were also performed in all groups.

RESULTS

The result of the study revealed that the SOD activities were lower for groups B (I/R + 1 h) and C (I/ R + 24 h) than for group A (sham group) (p < 0.05). In addition, SOD activities were higher in groups D (I/ R + 1 h FK-506) and E (I/R + 24 h FK-506) than in groups B (I/R + 1 h) and C (I/R + 24 h) (p < 0.05). MDA levels, MPO activities and the number of apoptotic cells were lower in group A (sham group) than in groups B (I/R + 1 h) and C (I/R + 24 h) (p < 0.05). In addition to these MDA levels, MPO activities and the number of apoptotic cells were higher in groups B (I/R + 1 h) and C (I/R + 24 h) as compared to groups D (I/R + 1 h FK-506) and E (I/R + 24 h FK-506) (p < 0.05).

CONCLUSION

The results suggest that the prophylactic use of FK-506 in an in situ ischemic neural tissue may prevent reperfusion injury.

Hemoglobin measurement patterns during noninvasive diffuse optical spectroscopy monitoring of hypovolemic shock and fluid replacement

The purpose of this study is to demonstrate the feasibility of broadband diffuse optical spectroscopy (DOS) for noninvasive optical monitoring of differentiating patterns of total tissue hemoglobin (THC), oxy- (OxyHb), and deoxyhemoglobin (DeOxyHb) concentrations during hypovolemic shock and subsequent fluid replacement with saline and whole blood. The goal of this DOS application is to determine the efficacy of resuscitation efforts at the tissue level rather than currently available indirect and invasive measurements of hemodynamic parameters. 16 New Zealand white rabbits are hemorrhaged 20% of their total blood volume. In resuscitated animals, shed blood volume is replaced with equal volume of crystalloid or whole blood (five animals each). Physiological variables (cardiac output, mean arterial pressure, systemic vascular resistance, hematocrit) are measured invasively, while (OxyHb) and (DeOxyHb) are measured during the interventions using broadband DOS. During the pure hypovolemic hemorrhages, the decrease in THC is mainly due to the decrease in (OxyHb), since the decrease in THC due to blood loss results in decreased tissue perfusion, with a resultant increased tissue extraction of oxygen. The hemorrhage with the whole blood resuscitation model shows significant changes in (OxyHb) during resuscitation phases due to the higher oxygen carrying capacity of whole blood, as opposed to the limited volume replacement effects and the decreased tissue oxygen content from the euvolemic anemia of the saline resuscitation. Broadband DOS noninvasive optical monitoring reveals distinct patterns of total tissue hemoglobin, oxy-, and deoxyhemoglobin during hemorrhage. Further studies are needed to confirm potential clinical utility and accuracy under more complex clinical conditions in animal models and patients.

Controversies in Fluid Resuscitation

The optimal degree of resuscitation in the initial control and resuscitative phase of trauma care remains unclear. Many attempts have been made with animal studies to determine the optimal degree and method of resuscitation. Human studies were first conducted in 1994 and the results were inconclusive and have not been replicated. The question of the volume, rate, and type of fluid to be infused for initial control and adequate resuscitation of the trauma patient remains to be answered.

Effect of Fluid Resuscitation on Acute Skeletal Muscle Ischemia-Reperfusion Injury after Hemorrhagic Shock in Rats

BACKGROUND

Severe extremity wounds with vascular injury are common in military trauma, and tourniquets are commonly used for hemorrhage control. The complications of tourniquet use in the setting of trauma are not well studied. This study investigated the combined effect of hemorrhagic shock and fluid resuscitation with Hextend (HX; BioTime, Inc) or lactated Ringer's (LR) on skeletal muscle subjected to tourniquet-induced ischemia-reperfusion injury.

STUDY DESIGN

Thirty male Sprague-Dawley rats underwent 33% arterial hemorrhage followed by 3 hours of tourniquet application. Before reperfusion, 10 animals each were resuscitated with lactated Ringer's (3 times shed volume) or HX (shed volume). Ten control animals received no resuscitation. Rats were euthanized 2 hours after tourniquet release and the tibialis anterior and medial gastrocnemius muscles were examined for edema (muscle wet weight) and viability (nitroblue tetrazolium reduction). Contralateral muscles served as controls for each animal, with results expressed as the ratio of the tourniquet limb to contralateral limb values.

RESULTS

The tibialis anterior and medial gastrocnemius muscles in all groups experienced edema, with all weight ratios greater than one. Resuscitation with HX resulted in significantly (p < 0.05) greater edema than did no resuscitation in both muscles and greater edema than with lactated Ringer's in the medial gastrocnemius. All groups experienced a loss of viability as well, with nitroblue tetrazolium reduction ratios less than one. Resuscitation with HX resulted in significantly less viability loss than did no resuscitation in the medial gastrocnemius. No significant differences in viability were seen in the tibialis anterior.

CONCLUSIONS

Resuscitation with HX or lactated Ringer's does not adversely affect muscle viability in ischemia-reperfusion injury. HX may be a better clinical choice when skeletal muscle ischemia-reperfusion injury is a risk, despite greater edema.

The efficacy of B-type natriuretic peptide for early identification of blood loss in traumatic injury

BACKGROUND

Because B-type natriuretic peptide (BNP) secretion has a direct linear correlation with intravascular volume status, it was assessed as an initial marker for blood loss (BL) in polytrauma patients.

METHODS

Hemodynamically unstable trauma patients between 18 and 45 years had serial BNP levels and hemoglobin (Hgb) levels obtained on admission, at 8 and 24 hours, and every morning during resuscitation.

RESULTS

The 14 patients were categorized into 2 groups based on the 24-hour trend in Hgb levels: clinically significant blood loss (Hgb decrease >3 g/dL) or no clinical blood loss (Hgb decrease <3 g/dL). On admission, the 5 patients in the no blood loss group had normal BNP levels, whereas the 9 patients in the BL group had below-normal BNP levels. Because patients in the BL category were resuscitated, their BNP levels normalized.

CONCLUSIONS

BNP levels below normal are indicative of intravascular volume loss in traumatically injured patients.

Prolonged controlled hemorrhagic shock in a swine model: is there a role for mechanical circulatory assistance?

Outcomes of mechanical circulatory assistance during hemorrhagic shock were evaluated in a swine model. Pigs were bled to a mean arterial pressure of 35 mm Hg (group I, n = 3) or 40 mm Hg (group II, n = 5; group III, n = 5), maintained there for 30 minutes, and then resuscitated with fluids alone (groups I and II) or fluids plus mechanical circulatory assistance (group III). Mean blood loss was greater in group I than in groups II or III (1,037 +/- 212 vs. 862 +/- 387 ml vs. 681 +/- 117 ml, respectively; I vs. III, p < 0.05) and survival was shorter (230 +/- 25.5 min vs. 709 +/- 251 min vs. 662 +/- 428 min, respectively; I vs. II or III, p < 0.05). Cardiac arrhythmia caused death in most cases. Mean biochemical parameters increased progressively in all cases. Left anterior descending coronary artery flow stayed relatively constant in group II but increased in group III. Superior mesenteric artery flow returned to baseline in group II but increased in group III. Cardiac output was similar in groups II and III, but SGOT levels significantly differed (750 +/- 135 U/L vs. 359 +/- 157 U/L; p < 0.005). These results suggest that the swine model will be useful for studying ways to improve outcomes after prolonged hemorrhagic shock.

Assessment of acid-base status and plasma lactate concentrations in arterial, mixed venous, and portal blood from dogs during experimental hepatic blood inflow occlusion

OBJECTIVE

To determine the effects of extended experimental hepatic blood flow occlusion (ie, portal triad clamping [PTC]) in dogs by measuring acid-base status and plasma lactate concentrations in arterial, mixed venous, and portal blood and evaluating the relationship between metabolic and concurrent hemodynamic changes.

ANIMALS

6 healthy Beagles.

PROCEDURE

During anesthesia with isoflurane, cardiac output and arterial blood pressure were measured. Arterial, mixed venous, and portal blood samples were collected simultaneously for blood gas analyses and plasma lactate measurements before PTC and at 8-minute intervals thereafter.

RESULTS

PTC resulted in severe hemodynamic and metabolic alterations. Eight minutes after PTC, significant decreases in cardiac index from a baseline value of 3.40 +/- 0.27 to 1.54 +/- 0.26 L/min/m2 and in mean arterial blood pressure from a baseline value of 74 +/- 6 to 43 +/- 6 mm Hg were recorded. After PTC, results indicative of lactic acidosis were found in portal blood at 16 minutes, in mixed venous at 32 minutes, and in arterial blood at 48 minutes. Significant differences in measured variables were also found between arterial and portal blood samples, between mixed venous and portal blood samples, and between arterial and mixed venous blood samples after PTC, compared with differences at baseline.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of mixed venous blood is preferable to analysis of arterial blood in the assessment of metabolic derangement. In a clinical setting, occluded portal blood is released to the systemic circulation, and the degree of reperfusion injury may depend on the metabolic status of pooled portal blood.

Prehospital care of the patient with major trauma

Recent research efforts have demonstrated that many longstanding practices for the prehospital resuscitation of trauma patients may be inappropriate under certain circumstances. For example, traditional practices, such as application of anti-shock garments and i.v. fluid administration to raise blood pressure, may even be detrimental in certain patients with uncontrolled bleeding, particularly those with penetrating injuries. ETI, although potentially capable of transiently prolonging a patient's ability to tolerate circulatory arrest, may also be harmful if overzealous PPV further compromises cardiac output, particularly in those patients with severe hemodynamic instability. In addition, if these procedures delay patient transport, any benefit that they may offer could be outweighed by the delay in definitive care. Although traditionally taught to "hyperventilate" the patient with severe head injury, current recommendations are to avoid this tactic unless there is evidence of herniation. Even time-honored traditions, such as universal spinal precautions and CPR during circulatory arrest, are being scrutinized [2,134]. Further prospective randomized clinical trials are needed to better define the role of many overlapping therapies in prehospital trauma care. Such research must specifically address and stratify the different mechanisms of injury, anatomic areas involved, and the physiologic staging of the injury. Furthermore, the efficacy of a single intervention may be masked by a confounding variable [5]. For example, a trial of an effective new HBOC in moribund patients that indicates no advantage in the study results may have been confounded by overzealous PPV, which may have led to suboptimal outcomes. It is hoped that, in the future, EMS physicians will be able to not only better discriminate in their management of patients with major trauma but also improve outcomes as a result.

Resuscitation in the new millennium

This article discusses resuscitation from a historical perspective; physiology; the optimal timing and volume for and fluids and endpoints of resuscitation; and the role of resuscitation in the future. Whether different types of victims of trauma should be resuscitated using different endpoints also is discussed.

Pharmacokinetics and pharmacodynamics of hydroxyethyl starch in hypovolemic pigs; a comparison of peripheral and intraosseous infusion

Intraosseous (i.o.) infusion is considered a useful technique for the administration of medications and fluids in emergency situations when peripheral intravascular access is not possible. This study investigated the effectiveness of i.o. versus intravenous (i.v.) infusion of hydroxyethyl starch (HES 200/0.5) in hypovolemic pigs. Twenty-three pigs (8- to 9-week-old) were anaesthesized, instrumented and blood was withdrawn (25-30 ml/kg) to < 50 mmHg mean arterial pressure (MAP). The animals were left untreated in haemorrhage for 30 min. Relevant haemodynamic parameters were monitored and blood samples were collected for blood gas and HES concentration analysis. Infusion of HES via i.v. or i.o. line (20 ml/kg per h) carried out over a period of 30 min for volume resuscitation and measurements were taken every 5 min. Infusion was discontinued after 30 min and the animals were monitored for 1 h. Analysis of HES-pharmacokinetics and pharmacodynamics revealed no significant differences between i.o. and the i.v. administration. The results demonstrate i.o. infusion of HES to be a rapid and effective method for fluid resuscitation in hypovolemic shock.

Human complement activation by polygeline and dextran 70

The complement cascade is activated during cardiopulmonary bypass (CPB) and in trauma victims. In order to study whether plasma expanders may contribute to complement activation in these settings, fresh human serum was incubated with dextran 70 and polygeline. C3-activation products and the terminal complement complex (TCC) were quantified in enzyme immunoassays. At 37 degrees C, dextran caused immediate, dose-dependent C3 activation and TCC formation with decline later in the rate of TCC formation relative to serum-saline controls. High doses of polygeline caused slight activation after 15-30 min. The authors tested also the activation under conditions comparable to those found during clinical CPB. Activation induced by dextran and polygeline was increased by dilution of the serum. Furthermore, the plasma expanders counteracted the well-known inhibitory effects of heparin (4 IU/ml) and moderate hypothermia (30 degrees C) on complement activation. The authors conclude that dextran, and to a lesser extent polygeline, may contribute to complement activation during CPB and other clinical settings such as shock treatment.