Asher Hirshberg

Minimizing dilutional coagulopathy in exsanguinating hemorrhage: a computer simulation.

BACKGROUND Current massive transfusion guidelines are derived from washout equations that may not apply to bleeding trauma patients. Our aim was to analyze these guidelines using a computer simulation. METHODS A combined hemodilution and hemodynamic model of an exsanguinating patient was developed to calculate the changes in prothrombin time (PT), fibrinogen, and platelets with bleeding. The model was calibrated to data from 44 patients. Time intervals to subhemostatic values of each coagulation test were calculated for a range of replacement options. RESULTS Prolongation of PT is the sentinel event of dilutional coagulopathy and occurs early in the operation. The key to preventing coagulopathy is plasma infusion before PT becomes subhemostatic. The optimal replacement ratios were 2:3 for plasma and 8:10 for platelets. Concurrent transfusion of plasma with blood is another effective strategy for minimizing coagulopathy. CONCLUSION Existing protocols underestimate the dilution of clotting factors in severely bleeding patients. The model presents an innovative approach to optimizing component replacement in exsanguinating hemorrhage.

MEDICAL CONSEQUENCES OF TERRORISM : THE CONVENTIONAL WEAPON THREAT

As long as gunpowder and explosives are used to solve disagreements between nations, ethnic groups, and individuals, victims of blast injury continue to arrive occasionally at trauma centers around the world. Bombs planted in crowded urban locations or suicide bombings continue to stress civilian EMS and urban medical systems. Although the clinical presentation depends on whether the blast occurs in open or confined quarters, open air, or water, the pattern of injury inflicted on the body is relatively consistent. The proximity to the detonating device is probably much more important than the size of the bomb. If not injured by secondary, tertiary, or other miscellaneous mechanisms of most conventional bombs with 1 to 20 kg of TNT, people at distances exceeding 6 m will probably not experience substantial blast-induced injury. Three systems are prone to injury. The first is the auditory system, with damage to the eardrum in milder cases and inner-ear injury in more severe cases. The alimentary tract with contusions, hematoma, and occasional perforation of a hollow viscus is the second system involved. Solid organs are rarely damaged in survivors of blast injury. Close proximity to the blast can impose traumatic amputation of limbs (i.e., arms and legs) and ear lobes. Most of these victims succumb to their injuries in the immediate post-injury phase, but the hallmark of blast injury is the involvement of the respiratory system. With expeditious evacuation performed by efficiently coordinated and highly skilled EMS personnel, more patients with blast injuries arrive with signs of life to the medical facility. At the medical facility, the staff need to triage many victims into urgent and nonurgent groups. Only lifesaving procedures should be performed during the initial phase. Later, medical care is directed at patients moved to ICUs. Prompt evacuation after necessary lifesaving procedures in the field; proper triage and distribution; prudent hospital triage and surgical care; and, last but not least, expert critical care provide the best possible outcome in such circumstances.

Planned reoperation for trauma: a two year experience with 124 consecutive patients.

Planned reoperation is a new approach to severe truncal trauma. A review of 124 patients treated over two years was undertaken. Penetrating injuries predominated (78%) involving primarily the abdomen or abdomen and chest. An abbreviated procedure was performed when direct hemostasis was impossible (102 patients), abrupt termination was required (56 patients), or the abdomen or chest could not be closed (20 patients). The techniques employed included packing, rapid skin closure, gastrointestinal interruption, rapid vascular control, temporary urinary diversion, stapled lung resection, and plastic bag closure. Seventy-three patients survived to undergo 101 operations. The first reoperation was planned in 52 patients and unplanned (either for bleeding or for abdominal compartment syndrome) in 21 patients. There were 14 missed injuries. The overall mortality rate was 58%. Survival was significantly better when the decision to abruptly terminate the initial procedure was made early and in patients undergoing planned reoperation. Wider adoption and better definition of the indications will result in more effective use of this approach.

Planned Reoperation for Severe Trauma

ObjectiveThe authors review the physiologic basis, indications, techniques, and results of the planned reoperation approach to severe trauma. Summary Background DataMultivisceral trauma and exsanguinating hemorrhage lead to hypothermia, coagulopathy, and acidosis. Formal resections and reconstructions in these unstable patients often result in irreversible physiologic insult. A new surgical strategy addresses these physiologic concerns by staged control and repair of the injuries. BackgroundThe authors review the literature. ResultsIndications for planned reoperation include avoidance of irreversible physiologic insult and inability to obtain direct hemostasis or formal abdominal closure. The three phases of the strategy include initial control, stabilization, and delayed reconstruction. Various techniques are used to obtain rapid temporary control of bleeding and hollow visceral spillage. Hypothermia, coagulopathy, and the abdominal compartment syndrome are major postoperative concerns. Definitive repair of the injuries is undertaken after stabilization. ConclusionPlanned reoperation offers a simple and effective alternative to the traditional surgical management of complex or multiple injuries in critically wounded patients.

Enteric Fistulas: Principles of Management

In the past decade, surgeons have seen a quiet but dramatic shift in clinical patterns of enteric fistulas. Despite advances in nutritional care, infection control, and surgical technique, an enterocutaneous fistula (ECF) remains a source of considerable morbidity and mortality. In addition, wide adoption of damage control and the open abdomen in trauma and emergency surgery have confronted surgeons with a new and especially vicious adversary: the enteroatmospheric (or exposed) fistula (EAF). These fistulas, occurring in the midst of an open abdominal wound, are very difficult to control and present a particularly lethal challenge. Such EAFs might well be the most common type of enteric fistula facing surgeons today. Yet this shift in clinical patterns from the classic ECF to the new EAF is still totally disregarded in major surgical texts. The aim of this review is to present current principles in the management of enteric fistulas. Additionally, we will demonstrate how traditional principles of managing enteric fistulas help us to better understand the physiology and natural history of EAFs and to deal effectively with this new challenge.

Damage control for abdominal trauma.

The damage control concept represents an extension of modern trauma resuscitation into the operating room. This surgical concept has found its most versatile and important use in severe abdominal trauma. The two critical concerns during damage control laparotomy are achieving hemostasis and preventing uncontrolled spillage of intestinal contents or urine. All else is secondary, and contrary to the traditional sequence of abdominal surgery, it is also deliberately disregarded. The common denominator of the many techniques presented in this article for a bail-out laparotomy is the need for a rapid decision, creative improvisation, and awareness that the outcome is determined by the patients physiologic envelope and not by anatomic integrity, which can be achieved at reoperation.

How does casualty load affect trauma care in urban bombing incidents? A quantitative analysis

BACKGROUND The aim of this modeling study was to examine how casualty load affects the level of trauma care in multiple casualty incidents and to define the surge capacity of the hospital trauma assets. METHODS The disaster plan of a U.S. Level I trauma center was translated into a computer model and challenged with simulated casualties based on 223 patients from 22 bombing incidents treated at an Israeli hospital. The model assigns providers and facilities to casualties and computes the level of care for each critical casualty from six variables that reflect the composition of the trauma team and access to facilities. RESULTS The model predicts a sigmoid-shaped relationship between casualty load and the level of care, with the upper flat portion of the curve corresponding to the surge capacity of the trauma assets of the hospital. This capacity is 4.6 critical patients per hour using immediately available assets. A fully deployed disaster plan shifts the curve to the right, increasing the surge capacity to 7.1. Overtriage rates of 50% and 75% shift the curve to the left, decreasing the surge capacity to 3.8 and 2.7, respectively. CONCLUSION This model defines the quantitative relationship between an increasing casualty load and gradual degradation of the level of trauma care in multiple casualty incidents, and defines the surge capacity of the hospital trauma assets as a rate of casualty arrival rather than a number of beds. The study demonstrates the value of dynamic computer modeling as an important tool in disaster planning.

Surgical resource utilization in urban terrorist bombing: a computer simulation.

BACKGROUND The objective of this study was to analyze the utilization of surgical staff and facilities during an urban terrorist bombing incident. METHODS A discrete-event computer model of the emergency room and related hospital facilities was constructed and implemented, based on cumulated data from 12 urban terrorist bombing incidents in Israel. RESULTS The simulation predicts that the admitting capacity of the hospital depends primarily on the number of available surgeons and defines an optimal staff profile for surgeons, residents, and trauma nurses. The major bottlenecks in the flow of critical casualties are the shock rooms and the computed tomographic scanner but not the operating rooms. The simulation also defines the number of reinforcement staff needed to treat noncritical casualties and shows that radiology is the major obstacle to the flow of these patients. CONCLUSION Computer simulation is an important new tool for the optimization of surgical service elements for a multiple-casualty situation.

Pulmonary tractotomy with selective vascular ligation for penetrating injuries to the lung.

BACKGROUND The operative management of penetrating lung injuries includes oversewing of small lung lacerations (pneumonorrhaphy), wedge resection, or anatomic resection. There are penetrating injuries of the lung for which oversewing of entrance and exit wounds will predispose to intrapulmonary hematoma or pulmonary venous-systemic air emboli, yet for which formal resection would be time consuming. The technique of pulmonary tractotomy with selective vascular ligation was developed in parallel with hepatotomy for liver injuries. PATIENTS AND METHODS Over the past 9 years, pulmonary tractotomy has been used 18 times in 16 patients at our institution. All patients were male. Their injuries were 12 gunshot and 4 stab wounds. RESULTS There were three deaths unrelated to the tractotomy. Five surviving patients developed complications. CONCLUSION Pulmonary tractotomy is a straight-forward procedure that controls deep hemorrhage from lung injuries and may obviate the need for formal resection.

Causes and patterns of missed injuries in trauma

Missed injuries have a bad reputation and are sometimes associated with serious morbidity for the patient and personal embarrassment for the surgeon. During a 10-year period, 123 missed injuries in 117 patients requiring re-operation were encountered in one trauma center. A retrospective review of causes and patterns was undertaken. The most common presentation was delayed hemorrhage (64 injuries). The colon, thoracic vasculature, chest wall arteries, and diaphragm were the most frequently involved sites. Forty-six injuries were overlooked during the diagnostic work-up, and 43 were missed during surgery. Technical problems with diagnosis and surgery accounted for 62% of missed injuries, whereas decision and judgment errors accounted for the rest. Further insight was provided by the classification of missed injuries into three types. Type I (20%) occurred outside the body area of clinical focus, whereas type II (69%) occurred within it. Type III (11%) resulted when instability of the patient necessitated interruption of the diagnostic work-up or exploration. Each type represents a different clinical pattern and dictates a specific preventive strategy.