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Biomedical subjects

A Hirshberg

Publications and source records attributed to A Hirshberg.

At least 19 recordsLinked to original sources
PubMed1999

Computer simulation of hypothermia during "damage control" laparotomy.

"Damage control" is a surgical strategy for the staged repair of severe trauma that aims to avoid an irreversible physiologic insult marked by a self-propagating combination of hypothermia, coagulopathy, and acidosis. The point beyond which the physiologic insult becomes irreversible, however, remains ill-defined. The aim of this study was to address this problem by means of a dynamic computer model of heat loss during laparotomy for exsanguinating hemorrhage. A single compartment model was developed using a graphic modeling tool and was implemented to calculate the time interval from the beginning of laparotomy to a core temperature of 32 degrees C, which is a marker of irreversible physiologic derangement in injured patients. A series of simulation runs showed that the exposed peritoneum is the dominant factor contributing to heat loss; the bleeding rate has a less marked effect. Elevation of the ambient temperature and rapid abdominal closure are effective interventions available to the surgeon to modify the heat loss curve. This study shows that during a "damage control" laparotomy for exanguinating hemorrhage the window of opportunity for salvage before the onset of an irreversible physiologic insult is no longer than 60 to 90 minutes.

Computer Simulation↗
PubMed1999

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.

Amputation, Traumatic↗
PubMed1999

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.

Computer Simulation↗
PubMed1999

Collagen fibres in the wall of odontogenic keratocysts: a study with picrosirius red and polarizing microscopy.

The collagen in the walls of 15 keratocysts was studied histochemically by staining sections with picrosirius red and examining them with polarizing microscopy. This was compared to 15 cases of dentigerous cyst and 15 cases of radicular cyst. Polarization colours of the collagen fibres were recorded according to their width. No differences were found between the polarization colours of thin fibres (<0.8 microm) in all three lesions; the polarization colours of thick fibres (1.6-2.4 microm) in keratocysts were significantly more greenish-yellow when compared with those of dentigerous cysts and radicular cysts. The staining of the collagen fibres in the keratocysts is similar to that reported in odontogenic neoplasms, which suggests that the stroma of keratocysts could be regarded not just as a structural support of the cyst wall, but as playing a part in the neoplastic behaviour of the cyst.

Analysis of Variance↗
PubMed1998

Beta-2-microglobulin-associated nodular amyloidosis of the tongue.

The tongue is an uncommon site for the deposition of beta-2-microglobulin amyloid. A case is presented of nodular amyloidosis of the tongue in a patient having prolonged hemodialysis. The lesions were small, firm, yellowish nodules on the lateral aspect of the tongue and were shown to be deposits of beta-2-microglobulin amyloid. The pathogenesis and differential diagnosis are discussed.

Amyloidosis↗
PubMed1997

The source of NMR-detected motional anisotropy of water in blood vessel walls.

2H Double quantum-filtered (DQF) NMR spectroscopy of deuterated water is sensitive to the presence of order in biological systems. This is because the only nuclei that are detected are those with residual quadrupolar interactions due to their anisotropic motion. In the present study, samples of aorta, coronary and carotid arteries, and vena cava were studied in parallel by 2H DQF NMR and by light microscopy. The average quadrupolar splitting, calculated from the NMR data, varies considerably among the different blood vessels, with high reproducibility for each type of vessel. Polarization microscopy examinations using collagen-specific staining with picrosirius red, have shown a variety of color profiles for the different blood vessels. These reflect different physical modes of aggregation (packing and thickness) of collagen fibers. A correlation was found between the NMR parameters and the color profiles of the picrosirius red-stained sections. Treating the blood vessels with 90% formic acid resulted in the elimination of the 2H DQF NMR signal. Histological analysis demonstrated a complete degradation of collagen and muscle, whereas the elastin filaments were preserved. Evidence is given that the 2H DQF NMR signal is dominated by the contribution of water molecules interacting with the collagen fibers.

Animals↗
PubMed1997

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 patient's physiologic envelope and not by anatomic integrity, which can be achieved at reoperation.

Abdominal Injuries↗
PubMed1997

Damage control for vascular injuries.

Circumstances that call for the use of damage control techniques involve multiple and complex injuries associated with significant hemodynamic compromise. This setting requires the rapid assessment and prioritization of injuries so that the greatest threat to survival may be addressed as soon as possible. Major vascular injuries are a common source for exsanguinating hemorrhage and must be addressed in an expeditious manner. Ischemia takes a lower priority than hemorrhage but should be addressed early unless doing so threatens systemic viability. Ligation, balloon catheter occlusion, and temporary intraluminal shunt insertion are the commonly useful techniques for temporizing the danger while plans are formulated for definitive reconstruction at a later time under better operative conditions. Contamination and infection are unfortunate realities in the damage control arena and are dealt with when feasible. In such circumstances, which are associated with a very high risk of morbidity and mortality, it is difficult to discern the outcome effects of specific injuries from the associated treatment techniques. Trends for improved survival of otherwise highly lethal injuries in institutions where these techniques are used provide at least presumptive testimony to their value. Large clinical series and supportive experimental data are not readily available to verify the physiologic benefits of the damage control approach. However, the increasingly popular use of these techniques in both urban and rural trauma management provides at least some hope for survival of traditionally devastating and frequently lethal injuries.

Amputation, Surgical↗
PubMed1997

Reoperation. Planned and unplanned.

Reoperation is an integral part of the damage control sequence. Each type of reoperation represents an entirely different operative profile with different tactical considerations. This article discusses in detail the key decisions and techniques of planned and unplanned reoperation.

Abdomen↗
PubMed1997

Experimental tongue cancer in desalivated rats.

A group of 39 rats underwent excision of the submandibular and sublingual glands and ligation of the parotid ducts through the midventral incision of the neck, while the control group (41 rats) underwent a sham operation. All rats were administered 4NQO in a final concentration of 0.001% in drinking water. At 7, 14, 22 and 28 weeks after administering 4NQO, both groups of rats were killed and their tongues dissected, inspected and then fixed in 10% buffered formalin for histopathological examination. Clinical examination during the first 14 weeks revealed that rats in both groups looked healthy and no differences in body weight were noticed. Afterwards, the average weight gain of the desalivated rats was lower than in the control group (P < 0.01). The number of macroscopic oral lesions increased with time in both groups. However, in the desalivated rats, the first identifiable lesions were seen as early as week 7, whereas in the control group macroscopic lesions were seen only after 22 weeks. Histological examination revealed more affected rats in the desalivated group in the first 14 weeks after administering the carcinogen; lesions showed more severe pathological changes including two cases with evidence of squamous cell carcinoma. The differences between the desalivated groups and control decreased after 22 weeks with almost no differences at the end of the experiment.

4-Nitroquinoline-1-oxide↗
PubMed1997

Myocardial O2 balance during fluid resuscitation in uncontrolled hemorrhage: computer model.

OBJECTIVE: To study myocardial oxygen balance during fluid resuscitation for uncontrolled hemorrhage. DESIGN: A computer simulation. MATERIALS AND METHODS: A mathematical model of the cardio-vascular system was used to simulate uncontrolled hemorrhage with and without fluid replacement. The parameters of initial bleeding rates, fluid replacement, and time intervals were selected to approximate typical values encountered in an urban emergency medical services system. The model was used to calculate myocardial oxygen supply and demand, and the time from injury to myocardial oxygen deficit was calculated for each fluid regimen. MAIN RESULTS: The model predicts an exponential decline in bleeding rate when no fluids are administered. Optimal fluid infusion rate was predicted as a function of initial bleeding rate. The time to a negative myocardial oxygen balance was shorter when a fluid bolus (100 mL/min or more) was given compared with no fluid administration. CONCLUSIONS: For uncontrolled hemorrhage at initial bleeding rates of 100 mL/min or more, the time interval from injury to cardiac oxygen deficit is inversely related to the infusion rate. A detailed study of the myocardial oxygen balance provides a pathophysiologic rationale for fluid restriction in the initial management of uncontrolled hemorrhage.

Computer Simulation↗
PubMed1997

Prolonged abdominal packing for trauma is associated with increased morbidity and mortality.

Abdominal packing and planned reoperation is a lifesaving technique for temporary control of hemorrhage in severely injured patients. Morbidity and mortality in this group of patients, however, remain significant. It is unclear whether the duration of packing impacts upon outcome. The purpose of this study is to evaluate the abscess, sepsis, and mortality rates associated with duration of abdominal packing. The records of 35 patients treated with abdominal packing between July 1994 and December 1995 who survived to reoperation were retrospectively reviewed. Evaluation included age; sex; mechanism; injuries; Abdominal Trauma Index; duration of packing; survival; and presence of abscess, sepsis or other infections. Patients packed for a total of 72 hours or less had lower abscess, sepsis, and mortality rates than those packed for more than 72 hours. The differences in abscess rate and mortality were statistically significant (P < 0.05). The Abdominal Trauma Index and mechanism of injury were similar for the two groups. Based on these results, we conclude that although abdominal packing is a useful technique in the severely injured patient, it is associated with greater morbidity and mortality when the duration of packing exceeds 72 hours.

Abdominal Abscess↗
PubMed1996

Transaxial gunshot injuries.

OBJECTIVE: To define the clinical characteristics of gunshot injuries across the truncal midline (transaxial injuries). DESIGN: A retrospective case-control study MATERIALS AND METHODS: Analysis of a consecutive series of 223 patients with gunshot injuries to the torso treated at one trauma center. Sixty-three patients with transaxial injuries were compared to 148 patients with unilateral bullet trajectories. MAIN RESULTS: The incidence of cardiac (8%), vascular (17%), and spinal (29%) injuries and the mortality rate (29%) were significantly higher among the 63 patients with transaxial injuries compared with 148 patients with unilateral injuries. Initial operative access to the wrong visceral cavity (10%), missed injuries (14%), and early reoperations (19%) were also more common in the transaxial group. CONCLUSIONS: A transaxial bullet trajectory identifies a distinct injury pattern associated with a high incidence of major visceral damage, intraoperative misadventures, and very high mortality.

Abdominal Injuries↗
PubMed1996

Duration of antibiotic treatment in surgical infections of the abdomen. Penetrating abdominal trauma.

Infection is a major cause of morbidity and mortality following penetrating abdominal trauma. Antibiotics are routinely used although their effectiveness has never been evaluated in a placebo-controlled randomised trial, and they have never been shown to reduce the incidence of post injury intra-abdominal, as opposed to wound, infections. The available evidence indicates that a single preoperative dose of an appropriate antibiotic is adequate prophylaxis for penetrating abdominal injuries. Postoperative antibiotics should be reserved for "late" (> 12 hours) operations for enteric perforations. The optimal duration of treatment under these circumstances is not well established. Fever and leucocytosis are poor indicators of the need for continued postoperative administration in the severely traumatised patient.

Abdominal Injuries↗