Practice management guidelines for the optimal timing of long-bone fracture stabilization in polytrauma patients: the EAST Practice Management Guidelines Work Group.
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Brain Injuries↗
Biomedical subjects
R J Simon
Publications and source records attributed to R J Simon.
A comparative assessment of public opinion toward immigrants and immigration policies.
"This article is part of a larger study of public attitudes toward immigration in seven countries that historically and currently have had different policies and practices vis-a-vis immigration. The countries involved are Australia, Canada, France, Germany, Great Britain, Japan and the United States. The time frame for which most of the public opinion data will be reported is from 1970 through 1995. The data have been collected from national surveys that were conducted in each of the countries."
Americas↗
Crystal structure of chemically synthesized [N33A] stromal cell-derived factor 1alpha, a potent ligand for the HIV-1 "fusin" coreceptor.
Stromal cell-derived factor-1alpha (SDF-1alpha ) is a member of the chemokine superfamily and functions as a growth factor and chemoattractant through activation of CXCR4/LESTR/Fusin, a G protein-coupled receptor. This receptor also functions as a coreceptor for T-tropic syncytium-inducing strains of HIV-1. SDF-1alpha antagonizes infectivity of these strains by competing with gp120 for binding to the receptor. The crystal structure of a variant SDF-1alpha ([N33A]SDF-1alpha ) prepared by total chemical synthesis has been refined to 2.2-A resolution. Although SDF-1alpha adopts a typical chemokine beta-beta-beta-alpha topology, the packing of the alpha-helix against the beta-sheet is strikingly different. Comparison of SDF-1alpha with other chemokine structures confirms the hypothesis that SDF-1alpha may be either an ancestral protein from which all other chemokines evolved or the chemokine that is the least divergent from a primordial chemokine. The structure of SDF-1alpha reveals a positively charged surface ideal for binding to the negatively charged extracellular loops of the CXCR4 HIV-1 coreceptor. This ionic complementarity is likely to promote the interaction of the mobile N-terminal segment of SDF-1alpha with interhelical sites of the receptor, resulting in a biological response.
Binding Sites↗
Hemorrhage exacerbates bacterial translocation at low levels of intra-abdominal pressure.
BACKGROUND: It has been shown previously that the adverse cardiopulmonary sequelae of increased intra-abdominal pressure (IAP) are worsened by hemorrhage and resuscitation. Bacterial translocation (BT) to the mesenteric lymph nodes (MLNs), liver, and spleen has also been shown to occur with increased IAP. OBJECTIVE: To investigate the hypothesis that BT associated with elevated IAP would be significantly increased after hemorrhage and resuscitation. MATERIALS AND METHODS: Anesthetized adult male rats had femoral artery and vein catheters placed, and an intra-abdominal catheter placed to measure IAP. Group 1 underwent surgery only and served as controls. Group 2 had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. Group 3 had a 25% hemorrhage, followed by resuscitation by infused lactated Ringer's solution and shed blood. Group 4 first had a 25% hemorrhage, resuscitated using infused lactated Ringer's solution and shed blood, and then had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. All groups were killed after 2 hours, and had MLNs, liver, and spleen harvested for quantitative cultures. RESULTS: Hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. An increase in IAP to 10 mm Hg resulted in a significant level of BT to the MLNs and liver on MacConkey II agar (P<.05), and a significant increase in the level of BT only to the liver on trypticase soy agar with 5% sheep's blood (P<.05). Hemorrhage and resuscitation did increase the level of BT to the liver and spleen when IAP was increased to 10 mm Hg (P<.05). CONCLUSIONS: In this model, hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. However, hemorrhage and resuscitation increased BT to the liver and spleen when IAP was increased to 10 mm Hg. This supports the concept that prior hemorrhage and resuscitation exacerbates the effects of increased IAP.
Abdomen↗
Intra-abdominal hypertension after life-threatening penetrating abdominal trauma: prophylaxis, incidence, and clinical relevance to gastric mucosal pH and abdominal compartment syndrome.
OBJECTIVE: To define the incidence, prophylaxis, and treatment of intra-abdominal hypertension (IAH) and its relevance to gut mucosal pH (pHi), multiorgan dysfunction syndrome, and the abdominal compartment syndrome (ACS). METHODS: Seventy patients in the SICU at a Level I trauma center (1992-1996) with life threatening penetrating abdominal trauma had intra-abdominal pressure estimated by bladder pressure. pHi was measured by gastric tonometry every 4 to 6 hours. IAH (intra-abdominal pressure> 25 cm of H2O) was treated by bedside or operating room laparotomy. RESULTS: Injury severity was comparable between patients who had mesh closure as prophylaxis for IAH (n = 45) and those who had fascial suture (n = 25). IAH was seen in 10 (22.2%) in the mesh group versus 13 (52%) in the fascial suture group (p = 0.012) for an overall incidence of 32.9%. Forty-two patients had pHi monitoring, and 11 of them had IAH. Of the 11 patients, eight patients (72.7%) had acidotic pHi (7.10 +/- 0.2) with IAH without exhibiting the classic signs of ACS. The pHi improved after abdominal decompression in six and none developed ACS. Only two patients with IAH and low pHi went on to develop ACS, despite abdominal decompression. Multiorgan dysfunction syndrome points and death were less in patients without IAH than those with IAH and in patients who had mesh closure. CONCLUSIONS: IAH is frequent after major abdominal trauma. It may cause gut mucosal acidosis at lower bladder pressures, long before the onset of clinical ACS. Uncorrected, it may lead to splanchnic hypoperfusion, ACS, distant organ failure, and death. Prophylactic mesh closure of the abdomen may facilitate the prevention and bedside treatment of IAH and reduce these complications.
Abdomen↗
Intestinal permeability correlates with severity of injury in trauma patients.
BACKGROUND: Increased intestinal permeability (IP) and the release of toxic intraluminal materials have been implicated in the systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) observed in patients after severe trauma. Previous studies of intestinal permeability have failed to demonstrate a correlation between early measurements of IP and indicators of injury severity. This study examines the relationship between standard measures of injury severity and the early (day 1) and delayed (day 4) changes in IP. Associations between IP and the development of SIRS, MOF, and infectious complications were also studied. METHODS: The metabolically inactive markers lactulose (L) and mannitol (M) were used to measure IP in 29 consecutive patients who sustained injuries that required admission to the surgical intensive care unit and in 10 healthy control subjects. Measurements were made within 24 hours of admission and on hospital day 4. Severity of injury was assessed by A Severity Characterization of Trauma (ASCOT), Trauma and Injury Severity Score (TRISS), Injury Severity Score (ISS), Revised Trauma Score (RTS), and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Postinjury infections and parameters of SIRS and MOF were recorded. RESULTS: The IP of healthy volunteers (L/M, 0.025 +/- 0.008) was within the normal range (L/M < or = 0.03), whereas the average IP in injured patients was increased both within 24 hours (L/M, 0.139 +/- 0.172) and on the fourth hospital day (L/M, 0.346 +/- 0.699). No significant correlation between severity of injury and increased IP was seen within 24 hours of injury. A significant correlation was seen on hospital day 4, however, with all severity indices measured (ASCOT: r = 0.93, R2 = 0.87, p < 0.001; TRISS: r = 0.93, R2 = 0.87, p < 0.001; ISS: r = 0.84, R2 = 0.70, p < 0.001; RTS: r = 0.68, R2 = 0.47, p = 0.002; APACHE II score: r = 0.51, R2 = 0.26, p = 0.04). Patients with markedly increased IP (L/M > or = 0.100) experienced a significant increase in the development of SIRS (83 vs. 44%; p = 0.03) and subsequent infectious complications (58 vs. 13%; p = 0.01) and showed close correlation with the multiple organ dysfunction scores (r = 0.87, R2 = 0.76, p < 0.001). CONCLUSION: These observations demonstrate that the increased IP observed after trauma correlates with severity of injury only after 72 to 96 hours and not within the initial 24 hours of injury. A large increase in IP is associated with the development of SIRS, multiple organ dysfunction, and an increased incidence of infectious complications.
Case-Control Studies↗
Effect of hemorrhage on superior mesenteric artery flow during increased intra-abdominal pressures.
BACKGROUND: Elevations in intra-abdominal pressure (IAP) adversely affect organ function. Prior hemorrhage and resuscitation exacerbates the cardiac and pulmonary effects of IAP. We have recently shown that superior mesenteric artery flow (SMAF) is reduced with increasing IAP. This study was designed to determine whether and how hemorrhage and resuscitation affects SMAF with increasing IAP. METHODS: Ten pigs were divided into two groups after placement of a Doppler flow probe around the proximal SMA and insertion of a pulmonary artery (PA) catheter. Group 1 underwent intraperitoneal infusion of fluid to increase IAP to 10, 20, 30, and 40 mm Hg followed by a 20-minute equilibration period at each IAP. Group 2 was hemorrhaged 20% of circulating volume followed by standard resuscitation. After equilibration, this group had IAP increased in the same manner as group 1. Cardiac output (CO), PA pressures, and SMAF were recorded 1 hour after laparotomy and after equilibration at each IAP. Comparisons were made using repeated measures of analysis of variance, Student's t test, and linear regression analysis. RESULTS: In group 2, a reduction in SMAF was noted at 30 and 40 mm Hg of IAP when compared with baseline (p = 0.009). This reduction was not seen in group 1. There was also a significant (p = 0.001) reduction in CO between baseline and all levels of increased IAP in group 2. This decrease was again not seen in group 1. The correlation between CO and SMAF in group 2 was r = 0.74, r2 = 0.55, p = 0.0001. There was no significant correlation between CO and SMAF in group 1. CONCLUSION: SMAF and CO are reduced with increasing IAP to a greater degree when preceded by hemorrhage and resuscitation. Although there is a strong correlation between the reductions in CO and SMAF, the reduction in SMAF is greater than the reduction in CO. This finding suggests that optimizing cardiac function alone during periods of even moderate levels of increased IAP may be inadequate to normalize SMAF. This lends further support for early abdominal decompression in the treatment of trauma patients with increased IAP.
Abdomen↗
Intra-abdominal hypertension and the abdominal compartment syndrome.
IAH causes multiple and profound physiologic abnormalities both within and outside the abdomen. IAP monitoring is easily performed by bladder measurements. Careful monitoring and prompt recognition and treatment of IAP are critical in patients after damage control surgery because IAH is extremely common in these patients. Use of mesh fascial prostheses at the initial celiotomy in high-risk patients may prevent the deleterious effects of IAH. IAH should be considered an earlier manifestation of ACS. Surgical intervention should be indicated by IAH and not delayed until ACS is clinically apparent.
Abdomen↗
Hemorrhage lowers the threshold for intra-abdominal hypertension-induced pulmonary dysfunction.
BACKGROUND: Intra-abdominal hypertension has been associated with pulmonary and cardiac dysfunctions. We have noted in the clinical scenario of hemorrhagic shock and resuscitation that avoidance of even moderate levels of increased intra-abdominal pressure, using prophylactic decompression, improves outcomes when compared with patients who were decompressed when intra-abdominal pressures went over 20 cm H2O. We hypothesized that prior hemorrhage and resuscitation exacerbates the cardiopulmonary dysfunction associated with intra-abdominal hypertension. METHODS: Ten anesthetized pigs underwent placement of arterial and pulmonary artery catheters and a Silastic intra-abdominal catheter for measuring and manipulating intra-abdominal pressure. Group 1 animals (n = 5) were subjected to increasing intra-abdominal pressures at 10 mm Hg increments up to a level of 40 mm Hg. Group 2 animals (n = 5) were exposed to a severe hemorrhage and resuscitation before the increasing intra-abdominal pressure protocol. RESULTS: Compared with baseline, hemorrhage and resuscitation caused a significant deterioration in cardiac output at intra-abdominal pressures of 10 mm Hg and above. Oxygenation was reduced at 30 and 40 mm Hg. These changes were not seen in group 1 animals. A significant difference was found between groups 1 and 2 in VT, PaCO2, and PaCO2/FIO2 ratio at an intra-abdominal pressure of 20 mm Hg. This difference was not seen at lower or higher pressures. CONCLUSIONS: Prior hemorrhage and resuscitation caused an earlier decline in cardiopulmonary function in the setting of increased intra-abdominal pressure. These data suggest that, when interpreting intra-abdominal pressures, the clinical scenario must be considered. Prior hemorrhage and resuscitation produce the adverse consequences of intra-abdominal hypertension at lower pressures than when intra-abdominal hypertension is the only insult.
Animals↗
Complex duodenal injuries.
Duodenal trauma, with early diagnosis and prompt treatment, can be managed effectively by simple surgical techniques. Severe duodenal injuries and those associated with major destruction of adjacent structures (the pancreaticobiliary complex or abdominal vessels) require a more thoughtful strategy that incorporates a careful consideration of the physiologic stability of the patient and the extent of local destruction. Figure 8 summarizes these concepts in an algorithm.
Algorithms↗
A reassessment of Doppler pressure indices in the detection of arterial lesions in proximity penetrating injuries of extremities: a prospective study.
This prospective study assessed the role of Doppler pressure indices (Ankle-Brachial Index [ABI] or Brachial Brachial Index [BBI]) in the evaluation for occult arterial injury from penetrating proximity extremity trauma (PET). A total of 258 patients with 323 PETs were evaluated by physical examination and Doppler pressure (ABI/BBI) determination. An ABI/BBI of < 0.9 was considered abnormal. The findings were compared with those of arteriography in all patients. Eleven injuries (3.4%) found on arteriography were associated with normal indices. Five of these injuries were treated by repair (4 patients) or angiographic embolization of a bleeding vessel (1 patient), all in lesions proximal to the knee or elbow joints. The other six lesions were observed without intervention. All of the 29 injuries associated with abnormal indices had positive arteriographic findings. The 4 lesions that were treated operatively were proximal and the remaining 25, all with distal penetration, were observed without observation. As compared to angiography, Doppler indices yielded the following results: 283 true-negative, 11 false-negative, 29 true-positive, and 0 false-positive, for a sensitivity of 72.5%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 96%. These data suggest that Doppler indices should be an integral part of the physical examination and can screen patients with proximal injuries for further studies such as duplex sonography or arteriography.
Adolescent↗
Types of criminal acts women are likely to commit.
In their article, Trice and Lamb misrepresented my 1975 work on women and crime by suggesting that I predicted that there would be a big increase in violent crime among young women as they become more "masculinized." In fact, what was predicted was that as more women entered the labor force, there would be a significant increase in property offenses, mostly white collar and financial crimes on the part of women.
Adult↗
A prospective randomized study of end points of resuscitation after major trauma: global oxygen transport indices versus organ-specific gastric mucosal pH.
BACKGROUND: Gastric tonometry, as a method of organ-specific monitoring of the status of the splanchnic circulation, has demonstrated prognostic and therapeutic implications in critically ill patients. The experience with this method in patients with trauma has been limited. STUDY DESIGN: Fifty-seven patients were prospectively randomized into two groups: group 1, n = 30, normalization and maintenance of gastric mucosal pH (pHi) at or above 7.3 and group 2, n = 27, maintenance of oxygen delivery index of 600 or an oxygen consumption index of greater than 150. The groups had statistically similar injury severity scores, lactate levels, and base deficits. RESULTS: Of the 44 patients with pHi greater than 7.3 at 24 hours, three (6.8 percent) died of multiple organ dysfunction syndrome as compared with seven (53.9 percent) of 13 in whom pHi was not optimized, p = 0.006. Optimization times for oxygen delivery index, oxygen consumption index, lactate levels, and base excess were similar between survivors and nonsurvivors. The time for pHi optimization was significantly longer in nonsurvivors. Multiple organ dysfunction syndrome points were significantly higher in patients who did not have pHi optimized within 24 hours (6.08 compared with 2.5, p = 0.03). Optimization time for pHi was predictive of mortality on multiple regression. Persistently low pHi was frequently associated with systemic or intra-abdominal complications. It was the first finding in all the nonsurvivors at least 48 to 72 hours before death. CONCLUSIONS: Gastric mucosal pH may be an important marker to assess the adequacy of resuscitation. Monitoring of pHi may provide early warning for systemic complications in the postresuscitation period.
Adolescent↗
Peptide aldehyde inhibitors of hepatitis A virus 3C proteinase.
Picornaviral 3C proteinases are a group of closely related thiol proteinases responsible for processing of the viral polyprotein into its component proteins. These proteinases adopt a chymotrypsin-like fold [Allaire et al. (1994) Nature 369, 72-77; Matthews et al. (1994) Cell 77, 761-771] and a display an active-site configuration like those of the serine proteinases. Peptide-aldehydes based on the preferred peptide substrates for hepatitis A virus (HAV) 3C proteinase were synthesized by reduction of a thioester precursor. Acetyl-Leu-Ala-Ala-(N,N'-dimethylglutaminal) was found to be a reversible, slow-binding inhibitor for HAV 3C with a Ki* of (4.2 +/- 0.8) x 10(-8) M. This inhibitor showed 50-fold less activity against the highly homologous human rhinovirus (strain 14) 3C proteinase, whose peptide substrate specificity is slightly different, suggesting a high degree of selectivity. NMR spectrometry of the adduct of the 13C-labeled inhibitor with the HAV-3C proteinase indicate that a thiohemiacetal is formed between the enzyme and the aldehyde carbon as previously noted for peptide-aldehyde inhibitors of papain [Lewis & Wolfenden (1977) Biochemistry 16,4890-4894; Gamcsik et al. (1983) J. Am. Chem. Soc. 105, 6324-6325]. The adduct can also be observed by electrospray mass spectrometry.
3C Viral Proteases↗
Evaluation of subxiphoid pericardial window used in the detection of occult cardiac injury.
We critically evaluated several diagnostic modalities (clinical criteria, subxiphoid pericardial window (SPW) and laparoscopy) used in the detection of occult cardiac injury in haemodynamically stable patients at high risk of cardiac injury. Over 5 years, 122 patients were admitted to a Level I trauma centre with such an injury. They sustained 69 stab wounds, and 53 gunshot wounds. Sites of penetration were: precordial (81), right chest (25), lateral chest (13), thoracoabdominal (40) and abdominal (19). Vital signs in the emergency room were (mean +/- SD): systolic BP, 111 +/- 23.2 mmHg; HR, 106 +/- 18.7; GCS, 13.6 +/- 1.3; and CVP, 17 +/- 7.8 cmH2O. SPW was performed in all patients and was positive for haemopericardium in 26 patients, 24 (92 per cent) of whom had a cardiac injury at operation. Two patients had pericardial lacerations without cardiac injury. In addition, 14 patients with lower precordial and thoracoabdominal wounds underwent laparoscopy. At laparoscopy, the pericardium was evaluated by transdiaphragmatic inspection in 10 patients. The presence (two) or absence (eight) of blood within the pericardium was accurately predicted and verified by SPW. Univariate and multiple logistic regression analysis of clinical data failed to reveal any significant predictor of cardiac injury. SPW remains the standard means of diagnosing occult cardiac injury in high-risk patients. Since the incidence of occult cardiac injury in haemodynamically stable patients is 20 per cent, SPW should be used liberally. Laparoscopy may have a role in evaluating the pericardium in the subgroup of patients with lower chest wounds, and it facilitates inspection of intra-abdominal viscera and diaphragm at the same time.
Adolescent↗
Current concepts in the use of cavitary endoscopy in the evaluation and treatment of blunt and penetrating truncal injuries.
The use of thoracoscopy in the patient with penetrating injury to the thorax is in its infancy. Although it is used mainly for diagnosis, evidence suggests that it will become a therapeutic tool during the initial management of the traumatized patient and in the postinjury period (early evacuation of retained hemothorax and the treatment of empyema). Although its role in injuries to the superior chest is clear, its role has not been established in the evaluation of the diaphragm. Both laparoscopy and thoracoscopy offer advantages in this area that must be considered when contemplating diagnosis and treatment. Further studies help define the place of these procedures for injuries in the thoracoabdominal area. The indications for cavitary endoscopy after truncal injury are summarized in Table 2. It must be remembered that experience in this field is rapidly increasing, and indications will change with new studies and new technology.
Abdominal Injuries↗
Gastric mucosal pH and oxygen delivery and oxygen consumption indices in the assessment of adequacy of resuscitation after trauma: a prospective, randomized study.
OBJECTIVE: To compare gastric mucosal pH (pHi) and global oxygen variables [Oxygen Delivery Index (DO2I) and Oxygen Consumption Index (VO2I)] as indicators of adequacy of resuscitation after major trauma. METHODS: Twenty-seven patients were prospectively randomized into two groups: group 1 (n = 11), normalization and maintenance of pHi at or above 7.30; and group 2 (n = 16), maintaining a DO2I of 600 and a VO2I of > 150. The groups had statistically similar injury severity scores, lactate, and base deficit. RESULTS: The goals of therapy were achieved within 24 hours of admission in 10 of the 11 patients in group 1 and in 15 of the 16 patients in group 2. One patient (9.1%) in group 1 died. This patient had transient stabilization of pHi to 7.3 and subsequently had persistent mucosal acidosis. Of the 10 patients with pHi > 7.3 at 24 hours, 9 survived. In group 2, 5 (31.3%) died. Four of the 5 nonsurvivors had achieved DO2I and VO2I goals, but had pHi < 7.3 at 24 hours. A comparison of time taken for optimization of DO2I, VO2I, lactate, base excess, and pHi showed pHi and lactate as the variables different in survivors and nonsurvivors. Six of the 8 patients who developed multiple organ dysfunction syndrome had pHi < 7.3 at 24 hours. Persistently low pHi was the first sign of bacteremia (3 patients), small bowel gangrene or pregangrene (2 patients), intestinal anastomotic leak (2 patients), intra-abdominal hypertension (4 patients), and intra-abdominal abscess (5 patients). It was the first finding in all the nonsurvivors at least 72 hours before death. CONCLUSIONS: pHi may be an important marker to assess the adequacy of resuscitation. pHi monitoring may provide early warning for systemic complications in the postresuscitation period.
Adolescent↗
The role of cavitary endoscopy in trauma.
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Abdominal Injuries↗