Bruce Crookes

Can near-infrared spectroscopy identify the severity of shock in trauma patients?

BACKGROUND Our recent experimental study showed that peripheral muscle tissue oxygen saturation (StO2), determined noninvasively by near-infrared spectroscopy (NIRS), was more reliable than systemic hemodynamics or invasive oxygenation variables as an index of traumatic shock. The purpose of this study was to establish the normal range of thenar muscle StO2 in humans and the relationship between shock state and StO2 in trauma patients. METHODS This was a prospective, nonrandomized, observational, descriptive study in normal human volunteers (n = 707) and patients admitted to the resuscitation area of our Level I trauma center (n = 150). To establish a normal StO2 range, an NIRS probe was applied to the thenar eminence of volunteers (normals). Subsequently, in a group of trauma patients, an NIRS probe was applied to the thenar eminence and data were collected and stored for offline analysis. StO2 monitoring was performed continuously and noninvasively, and values were recorded at 2-minute intervals. Five moribund trauma patients were excluded. Members of our trauma faculty, blinded to StO2 values, classified each patient into one of four groups (no shock, mild shock, moderate shock, and severe shock) using conventional physiologic parameters. RESULTS Mean +/- SD thenar StO2 values for each group were as follows: normals, 87 +/- 6% (n = 707); no shock, 83 +/- 10% (n = 85); mild shock, 83 +/- 10% (n = 19); moderate shock, 80 +/- 12% (n = 14); and severe shock, 45 +/- 26% (n = 14). The thenar StO2 values clearly discriminated the normals or no shock patients and the patients with severe shock (p < 0.05). CONCLUSION Decreased thenar muscle tissue oxygen saturation reflects the presence of severe hypoperfusion and near-infrared spectroscopy may be a novel method for rapidly and noninvasively assessing changes in tissue dysoxia.

Secondary ultrasound examination increases the sensitivity of the FAST exam in blunt trauma.

INTRODUCTION Approximately one third of stable patients with significant intra-abdominal injury do not have significant intraperitoneal blood evident on admission. We hypothesized that a delayed, repeat ultrasound study (Secondary Ultrasound--SUS) will reveal additional intra-abdominal injuries and hemoperitoneum. METHODS We performed a prospective observational study of trauma patients at our Level I trauma center from April 2003 to December 2003. Patients underwent an initial ultrasound (US), followed by a SUS examination within 24 hours of admission. Patients not eligible for a SUS because of early discharge, operative intervention or death were excluded. All US and SUS exams were performed and evaluated by surgical/emergency medicine house staff or surgical attendings. RESULTS Five hundred forty-seven patients had both an initial US and a SUS examination. The sensitivity of the initial US in this patient population was 31.1% and increased to 72.1% on SUS (p < 0.001) for intra-abdominal injury or intra-abdominal fluid. The specificity for the initial US was 99.8% and 99.8% for SUS. The negative predictive value was 92.0% for the initial US and increased to 96.6% for SUS (p = 0.002). The accuracy of the initial ultrasound was 92.1% and increased to 96.7% on the SUS (p < 0.002). No patient with a negative SUS after 4 hours developed clinically significant hemoperitoneum. CONCLUSION A secondary ultrasound of the abdomen significantly increases the sensitivity of ultrasound to detect intra-abdominal injury.

Modified rapid deployment hemostat bandage reduces blood loss and mortality in coagulopathic pigs with severe liver injury.

BACKGROUND Hemostasis can be difficult to achieve after blunt abdominal trauma, especially if the patient is coagulopathic. The U.S. Food and Drug Administration has recently approved a hemostatic dressing for treating bleeding after extremity trauma (RDH bandage; Marine Polymer Technologies, Cambridge, MA). It has not been evaluated for internal bleeding after trauma. We redesigned this dressing for internal use, and then tested whether this modified bandage (Miami-modified Rapid Deployment Hemostat) could achieve hemostasis when used as an adjunct to standard laparotomy pad packing in a pig model of severe liver injury with coagulopathy. METHODS Anesthetized swine (35-45 kg) received an isovolemic 45% blood volume replacement with refrigerated Hextend (6% hetastarch). Core body temperature was maintained at 33-34 degrees C with intra-abdominal ice packs. A coagulopathic condition was documented by thromboelastography. At this point a severe liver injury was induced by the avulsion of the left lateral hepatic lobe, then the pigs were randomized to treatment with either standard abdominal packing (control) or packing plus Miami-modified Rapid Deployment Hemostat. Two series of experiments were conducted. In series one (n = 14), the abdomen was closed and the animals were observed with no resuscitation. After one hour, the abdomen was opened, the packing was removed and the presence of bleeding was noted. In series two (n = 10), the abdomen was closed and the animal resuscitated with one unit of blood plus as much lactated Ringers intravenous fluid (IVF) as required to maintain a mean arterial pressure (MAP) > 70 mm Hg. After one hour, the packing was removed, the abdomen closed, and data were collected for an additional two hours. RESULTS Series one: 6/7 animals in the control group had continued bleeding at one hour; 1/7 animals in the treatment group had active bleeding (p = 0.0291). Series two: With control vs. Miami-modified Rapid Deployment Hemostat, the three-hour survival was zero vs. 80% (p = 0.0476). The total blood loss was 1.2 +/- 0.1 vs. 0.3 +/- 0.1 mL/kg/min (p = 0.001) and the IVF requirement was 1.6 +/- 0.3 vs. 0.6 +/- 0.3 mL/kg/min (p = 0.026). CONCLUSIONS The Miami-modified Rapid Deployment Hemostat bandage significantly reduced mortality, blood loss, and fluid requirements when used as an adjunct to standard abdominal packing following severe liver injury in coagulopathic pigs [corrected].

Management of the Most Severely Injured Spleen A Multicenter Study of the Research Consortium of New England Centers for Trauma (ReCONECT)

OBJECTIVE To determine the rate and predictors of failure of nonoperative management (NOM) in grade IV and V blunt splenic injuries (BSI). DESIGN Retrospective case series. SETTING Fourteen trauma centers in New England. PATIENTS A total of 388 adult patients with a grade IV or V BSI who were admitted between January 1, 2001, and August 31, 2008. MAIN OUTCOME MEASURES Failure of NOM (f-NOM). RESULTS A total of 164 patients (42%) were operated on immediately. Of the remaining 224 who were offered a trial of NOM, the treatment failed in 85 patients (38%). At the end, 64% of patients required surgery. Multivariate analysis identified 2 independent predictors of f-NOM: grade V BSI and the presence of a brain injury. The likelihood of f-NOM was 32% if no predictor was present, 56% if 1 was present, and 100% if both were present. The mortality of patients for whom NOM failed was almost 7-fold higher than those with successful NOM (4.7% vs 0.7%; P = .07). CONCLUSIONS Nearly two-thirds of patients with grade IV or V BSI require surgery. A grade V BSI and brain injury predict failure of NOM. This data must be taken into account when generalizations are made about the overall high success rates of NOM, which do not represent severe BSI.

Oxygen saturation determined from deep muscle, not thenar tissue, is an early indicator of central hypovolemia in humans

Objective:To compare the responses of noninvasively measured tissue oxygen saturation (Sto2) and calculated muscle oxygen tension (Pmo2) to standard hemodynamic variables for early detection of imminent hemodynamic instability during progressive central hypovolemia in humans. Design:Prospective study. Setting:Research laboratory. Subjects:Sixteen healthy human volunteers. Interventions:Progressive lower body negative pressure (LBNP) to onset of cardiovascular collapse. Measurements and Main Results:Noninvasive measurements of blood pressures, heart rate, and stroke volume were obtained during progressive LBNP with simultaneous assessments of Sto2, Pmo2, and muscle oxygen saturation (Smo2). Forearm Smo2 and Pmo2 were determined with a novel near infrared spectroscopic measurement device (UMMS) and compared with thenar Sto2 measured by a commercial device (HT). All values were normalized to the duration of LBNP exposure required for cardiovascular collapse in each subject (i.e., LBNP maximum). Stroke volume was significantly decreased at 25% of LBNP maximum, whereas blood pressure was a late indicator of imminent cardiovascular collapse. Pmo2 (UMMS) was significantly decreased at 50% of maximum LBNP while Smo2 (UMMS) decreased at 75% of maximum LBNP. Thenar Sto2 (HT) showed no statistical change throughout the entire LBNP protocol. Conclusions:Spectroscopic assessment of forearm muscle Po2 and Smo2 provides noninvasive and continuous measures that are early indicators of impending cardiovascular collapse resulting from progressive reductions in central blood volume.

Inappropriate Prehospital Ventilation in Severe Traumatic Brain Injury Increases In-Hospital Mortality

In the setting of acute brainstem herniation in traumatic brain injury (TBI), the use of hyperventilation to reduce intracranial pressure may be life-saving. However, undue use of hyperventilation is thought to increase the incidence of secondary brain injury through direct reduction of cerebral blood flow. This is a retrospective review determining the effect of prehospital hyperventilation on in-hospital mortality following severe TBI. All trauma patients admitted directly to a single level 1 trauma center from January 2000 to January 2007 with an initial Glasgow Coma Scale (GCS) score <or=8 were included in the study (n = 77). Patients without documented or with late (>20 min) arterial blood gas at presentation (n = 12) were excluded from the study. The remaining population (n = 65) was sorted into three groups based on the initial partial pressure of carbon dioxide: hypocarbic (Pco(2) < 35 mm Hg), normocarbic (Pco(2) 35-45 mm Hg), and hypercarbic (Pco(2) > 45 mm Hg). Outcome was based on mortality during hospital admission. Survival was found to be related to admission Pco(2) in head trauma patients requiring intubation (p = 0.045). Patients with normocarbia on presenting arterial blood gas testing had in-hospital mortality of 15%, significantly improved over patients presenting with hypocarbia (in-hospital mortality 77%) or hypercarbia (in-hospital mortality 61%). Although there are many reports of the negative impact of prophylactic hyperventilation following severe TBI, this modality is frequently utilized in the prehospital setting. Our results suggest that abnormal Pco(2) on presentation after severe head trauma is correlated with increased in-hospital mortality. We advocate normoventilation in the prehospital setting.

Blunt pancreatoduodenal injury: A multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT)

OBJECTIVES To evaluate the safety of nonoperative management (NOM), to examine the diagnostic sensitivity of computed tomography (CT), and to identify missed diagnoses and related outcomes in patients with blunt pancreatoduodenal injury (BPDI). DESIGN Retrospective multicenter study. SETTING Eleven New England trauma centers (7 academic and 4 nonacademic). PATIENTS Two hundred thirty patients (>15 years old) with BPDI admitted to the hospital during 11 years. Each BPDI was graded from 1 (lowest) to 5 (highest) according to the American Association for the Surgery of Trauma grading system. MAIN OUTCOME MEASURES Success of NOM, sensitivity of CT, BPDI-related complications, length of hospital stay, and mortality. RESULTS Ninety-seven patients (42.2%) with mostly grades 1 and 2 BPDI were selected for NOM: NOM failed in 10 (10.3%), 10 (10.3%) developed BPDI-related complications (3 in patients in whom NOM failed), and 7 (7.2%) died (none related to failure of NOM). The remaining 133 patients were operated on urgently: 34 (25.6%) developed BPDI-related complications and 20 (15.0%) died. The initial CT missed BPDI in 30 patients (13.0%); 4 of them (13.3%) died but not because of the BPDI. The mortality rate in patients without a missed diagnosis was 8.8% (P = .50). There was no correlation between time to diagnosis and length of hospital stay (Spearman r = 0.06; P = .43). The sensitivity of CT for BPDI was 75.7% (76% for pancreatic and 70% for duodenal injuries). CONCLUSIONS The NOM of low-grade BPDI is safe despite occasional failures. Missed diagnosis of BPDI continues to occur despite advances in CT but does not seem to cause adverse outcomes in most patients.

Frequency of Inappropriate Continuation of Acid Suppressive Therapy After Discharge in Patients Who Began Therapy in the Surgical Intensive Care Unit

Study Objective. To determine the frequency with which patients who begin to receive stress ulcer prophylaxis in the surgical intensive care unit (SICU) are discharged receiving inappropriate acid suppressive therapy (AST).

Evaluation of Feeding Intolerance in Patients with Pentobarbital-Induced Coma

BACKGROUND: There is considerable debate regarding the appropriateness of feeding patients by the enteral route in conjunction with pentobarbital coma therapy. OBJECTIVE: To determine the incidence of feeding intolerance (FI) in patients receiving pentobarbital in conjunction with enteral nutrition (EN). METHODS: A retrospective, observational evaluation of patients (>14 y of age) who received a therapeutic pentobarbital coma in combination with EN was conducted. Patients were divided into groups, based on the occurrence of FI defined as aspiration of gastric residuals greater than 75 mL for 2 consecutive measurements. RESULTS: Forty-eight percent (29 of 61) of patients experienced FI based on our definition. The median pentobarbital infusion rate did not differ significantly between patients who experienced FI versus those who did not (median [intraquartile range, IQR] 1.8 mg/kg/h [1.4, 2.1] vs 1.7 mg/kg/h [1.4, 2.5]; p = 0.680). The total pentobarbital bolus dose during the first 24 hours of therapy was lower in patients who experienced FI (700 mg [225, 980] vs 1000 mg [600, 1475]; p = 0.029). Median duration of pentobarbital therapy was comparable between groups (141.0 h [93.3, 217.3] vs 116.3 h [64.0, 174.8]; p = 0.115). Other factors with the potential to influence FI, such as catecholamines, neuromuscular blockade, and hyperglycemia, were similar between groups. The higher narcotic doses and greater percentage of patients receiving benzodiazepines in the FI group warrants further study. CONCLUSIONS: Pentobarbital therapy did not preclude use of EN in the entire study population. In addition, FI did not occur at a greater frequency in patients who received a higher dosage, a longer duration, or an earlier initiation of pentobarbital therapy.