Gregory Timberlake

Hypercoagulability is most prevalent early after injury and in female patients

BACKGROUND Hypercoagulability after injury is a major source of morbidity and mortality. Recent studies indicate that there is a gender-specific risk in trauma patients. This study was performed to determine the course of coagulation after injury and to determine whether there is a gender difference. We hypothesized that hypercoagulability would occur early after injury and that there would be no difference between men and women. METHODS This was a prospective cohort study. Inclusion criteria were admission to the intensive care unit, Injury Severity Score > 4, and the ability to obtain consent from the patient or a relative. A Thrombelastograph (TEG) analysis was performed and routine coagulation parameters and thrombin-antithrombin complexes were measured within 24 hours of injury and then daily for 4 days. RESULTS Sixty-five patients met criteria for entry into the study. Their mean age was 42 +/- 17 years and their mean Injury Severity Score was 23 +/- 12. Forty patients (62%) were men. The prevalence of a hypercoagulable state by TEG was 62% on day 1 and 26% on day 4 (p < 0.01). Women were significantly more hypercoagulable on day 1 than men as measured by the time to onset of clotting (women, 2.9 +/- 0.7 minutes; men, 3.9 +/- 1.5 minutes; p < 0.01; normal, 3.7-8.3 minutes). Mean platelet counts, international normalized ratios, and partial thromboplastin times were within normal limits throughout the study. Thrombin activation as measured by thrombin-antithrombin complexes decreased from 34 +/- 15 microg/L on day 1 to 18 +/- 8 microg/L (p < 0.01) on day 4, consistent with the prevalence of hypercoagulability by TEG. CONCLUSION Hypercoagulability after injury is most prevalent during the first 24 hours. Women are more hypercoagulable than men early after injury. The TEG is more sensitive than routine coagulation assays for the detection of a hypercoagulable state.

Medical complications of head injury

There are many common and significant medical complications of head injury. These include (1) cardiovascular problems such as hyperdynamic state, myocardial injury, and dysrhythmias; (2) respiratory changes such as neurogenic pulmonary edema, hypoxia, abnormal ventilatory patterns, pulmonary infections, and pulmonary emboli secondary to deep vein thrombosis; (3) consumption coagulopathy; (4) water and electrolyte derangements--hypo- and hypernatremia; (5) hypothalamic/pituitary dysfunction--syndrome of inappropriate secretion of antidiuretic hormone and diabetes insipidus; (6) increased general metabolism with loss of immunocompetence, respiratory compromise, and complications of decreased activity; (7) gastrointestinal difficulties, particularly stress gastritis; and (8) infectious problems including those related to contamination from open wounds and foreign bodies such as monitors.

Autotransfusion of Blood Contaminated by Enteric Contents; A Potentially Life-saving Measure in the Massively Hemorrhaging Trauma Patient?

The role of autotransfusion of shed blood is well established in thoracic, abdominal, vascular, and orthopedic elective surgery. When hollow viscera or infected organs are uninvolved, autotransfusion is also well accepted in trauma surgery. Less clear is whether shed blood from an injury violating hollow organs in the abdomen can be used safely in the trauma patient. We retrospectively identified 11 patients with penetrating thoracoabdominal trauma who had received enteric contaminated shed blood, processed by the Haemonetics Cell Saver, and reviewed their records for infectious morbidity or mortality. All patients received parenteral broad-spectrum antibiotics. Three patients developed infectious wound complications, one probably nosocomial from the intensive care unit. No patient developed intra-abdominal sepsis and no deaths were reported. Based on the results of this preliminary result, it may be appropriate to use autotransfusion of shed blood in trauma patients with gastrointestinal injuries, if banked blood is not readily available and the patients receive perioperative broad-spectrum antibiotics.

Rectal pH measurement in tracking cardiac performance in a hemorrhagic shock model.

OBJECTIVE AND DESIGN We evaluated the utility of rectal mucosal pH measurement for tracking cardiac performance in hemorrhagic shock as compared with gastric tonometry. MATERIALS AND METHODS Hemorrhagic shock was induced in five adult swine to a mean arterial pressure of 45-65 mm Hg. Hypotension was maintained for 30 minutes, resuscitation was accomplished with the shed blood and lactated Ringers solution (3x blood volume). Gastric tonometry, rectal pH, and oxygen transport data were obtained at baseline, 0, and 30 minutes after onset of hypotension and after resuscitation. RESULTS Intramucosal pH readings from gastric tonometry and rectal mucosal pH both showed a significant change from baseline to 0 and 30 minutes after onset of hypotension. Data after resuscitation were found to be statistically the same as baseline values. CONCLUSIONS Rectal mucosal pH tracks cardiac performance as well as does gastric tonometry in hemorrhagic shock without as many limitations.

Resolution of experimental pneumothorax in rabbits by oxygen therapy

The treatment of asymptomatic patients with small pneumothoraces (ie, less than 20% by volume) has included observation, tube thoracostomy, and operation. When observation is used, the anticipated expansion of the lung has been estimated to be 1.25% of the lung volume daily. This study was designed to evaluate the use of inhaled oxygen as a method to accelerate the resolution of a pneumothorax in a rabbit model. Experimental pneumothoraces were created in 23 white New Zealand rabbits. Group 1 (9 rabbits) were placed in a cage with room air and group 2 (11 rabbits) were placed in a cage with high oxygen concentration. Three rabbits died before completion of the study. Serial chest roentgenograms were performed until the pneumothoraces resolved. The majority of rabbits treated with oxygen had resolution of their pneumothoraces by 36 hours, whereas the majority of rabbits treated with room air did not show complete resolution before 48 hours. Biopsies showed no evidence of damage secondary to oxygen treatment. Oxygen treatment was found to be significantly better in the early resolution of pneumothoraces when compared with room air. This establishes an alternative treatment for some pneumothoraces that are small and asymptomatic.

Thromboembolism as a complication of myocardial contusion: a new capricious syndrome.

Myocardial contusion is becoming more frequently recognized as a concomitant of blunt chest and abdominal trauma. Thromboembolism is an infrequent, but serious, complication of myocardial contusion and management is controversial. We report a case and review the literature of thromboembolism complicating blunt heart injury, and suggest a protocol to prevent this complication.

Resolution of experimental pneumothorax in rabbits by graded oxygen therapy.

BACKGROUND Small pneumothoraces have been treated by observation and tube thoracostomy in asymptomatic patients. Using a rabbit model, we demonstrated previously that inspired oxygen at 60% FiO2 hastened the time to resolution of complete pneumothoraces compared with room air. The present study was designed to evaluate the use of lower levels of inspired oxygen and to establish a dose-response curve for the treatment of experimental pneumothoraces. METHODS Forty New Zealand White rabbits were divided randomly into four groups: room air (21%) and 30, 40, and 50% FiO2. Experimental pneumothoraces were created in the rabbits, and the animals were placed in cages with the designated level of inspired oxygen. Serial chest radiographs were performed until the pneumothoraces resolved. RESULTS Pneumothoraces treated with room air resolved in 61.65 +/- 12.30 hours. Those treated with 30% FiO2 resolved in 42.90 +/- 5.97 hours, with 40% FiO2 in 35.80 +/- 4.26 hours, and with 50% FiO2 in 33.80 +/- 4.66 hours. CONCLUSION These results show a statistically significant (p < 0.01) dose-dependent improvement in the resolution of pneumothoraces with increasing levels of inspired oxygen. Supplemental oxygen therapy may be used to facilitate the resolution of small, uncomplicated pneumothoraces.

Trauma laparotomy in a rural setting before transfer to a regional center: does it save lives?

BACKGROUND In the rural setting, long distances may necessitate that a patient undergo emergency laparotomy before transfer to a regional trauma center for definitive management. The purpose of this study was to review the experience of three regional trauma centers with such treated patients. METHODS This study was a retrospective chart review of patients who underwent emergency laparotomy for trauma before transfer, identified from the respective databases of participating centers over a 6-year period. RESULTS Fifty-six patients met the study criteria. Twenty-six (46%) were transferred primarily for management of the abdominal injury, and 14 of these patients (25% overall) underwent damage control procedures. Overall survival was 82%. Logistic regression demonstrated that transfer for treatment of the extra-abdominal injury was the only significant predictor of survival (odds ratio, 34.33; 95% confidence interval, 1.80-655.24). CONCLUSION Although patients undergoing laparotomy who were subsequently transferred for management of abdominal injury have reasonable outcome, patients transferred primarily for management of extra-abdominal injury seem to have a survival advantage.

Enalaprilat improves systemic cardiovascular parameters and mesenteric blood flow during hypotensive resuscitation from hemorrhagic shock in dogs.

Resuscitative interventions that improve mesenteric perfusion without causing instability in systemic arterial pressures may be helpful for improving trauma patient outcomes. Blocking angiotensin II formation with enalaprilat may be such an intervention. Two questions were addressed in this two-part study investigating resuscitation from hemorrhagic shock in dogs: Can systemic arterial pressures be maintained while administering a constant rate infusion of enalaprilat during resuscitation, and can enalaprilat improve cardiovascular status during resuscitation? Animals were hemorrhaged to a mean arterial pressure (MAP) of 40 to 45 mmHg for 30 min and then 30 to 35 mmHg for 30 min. Group I (n = 5) was resuscitated to a MAP 60 to 65 mmHg with enalaprilat (0.02 mg/kg/h). Group II was resuscitated to a MAP 40 to 45 mmHg with (n = 5) or without (n = 5) enalaprilat. Resuscitation in both groups consisted of intermittent intravenous lactated Ringers solution (60 mL/kg/h) to reach and maintain the target MAPs. Systemic arterial pressures were unaffected by enalaprilat during resuscitation in Group I, allowing us to proceed to the second study. During severely hypotensive resuscitation (Group II), systemic arterial pressures were also stable and enalaprilat administration was associated with increases (P ≤ 0.02) in cardiac index (+1.2 L/min/m2), stroke volume index (SVI) (+14.5 mL/m2), superior mesenteric artery flow (+80 mL/min), stroke work (+561 mmHg/mL/m2), and left ventricular power output (+55.7 mmHg/L/min/m2). Corresponding increases were not observed in controls. We conclude that administration of a constant rate infusion of enalaprilat during resuscitation can be accomplished without causing a hypotensive crisis. Since enalaprilat significantly improved cardiovascular status including mesenteric perfusion even during intentional hypotension, it has potential value for improving the treatment of trauma patients.

Myocardial performance after contusion with concurrent hypovolemia

Myocardial contusion may present as a benign nonclinical event or a life-threatening emergency. Although cardiac output is recognized to be decreased with major contusion, the contribution of hypovolemic shock to myocardial dysfunction is unclear. This study was designed to evaluate the relationship between myocardial contusion and hypovolemic shock. After Sprague-Dawley rats were anesthetized, contusions were administered at either 80 psi or 120 psi. Half of each group then underwent hypovolemic shock. After 24 hours of recovery, cardiac hemodynamics were studied in each subgroup using the Neely-Langendorff apparatus. Isoenzymes and histology were evaluated as well. The data showed that rats undergoing hypovolemic shock in each subgroup had a significant decrease in cardiac output when compared with their controls. This decrease was more pronounced in the 120-psi group. Cardiac isoenzyme levels were elevated in all groups. Microscopic evaluations showed contusion in the controls and necrosis in the shock groups. Patients whose injuries are compatible with myocardial contusion and hypovolemic shock should be resuscitated quickly and evaluated for myocardial dysfunction secondary to infarction.