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Biomedical subjects

D H Wisner

Publications and source records attributed to D H Wisner.

At least 19 recordsLinked to original sources
PubMed2001

Gastric rupture and massive pneumoperitoneum after bystander cardiopulmonary resuscitation.

Gastric perforation is a rare complication of cardiopulmonary resuscitation. The majority of reported cases have been associated with difficult airway management or esophageal intubation. There has been only one previous case report in which this complication could be attributed solely to mouth-to-mouth ventilation. We present a case of simple bystander cardiopulmonary resuscitation that resulted in gastric perforation.

Adult↗
PubMed2001

Basal release of nitric oxide and its interaction with endothelin-1 on single vessel hydraulic permeability.

BACKGROUND: Both endothelin-1 (ET-1) and nitric oxide (NO) are released by the endothelium and are implicated in modulating the permeability of the endothelial barrier. The present study was designed to examine the interaction between ET-1 and NO and its influence on microvascular permeability as well as the role of NO in maintaining microvascular permeability. To isolate the direct effect of ET-1 and NO, experiments were conducted under conditions where hydraulic and oncotic pressures were controlled. METHODS: Postcapillary venules in the rat mesentery were perfused in situ and paired measurements of hydraulic permeability (Lp) obtained using the modified Landis micro-occlusion method. The effect of basal endogenous NO was tested by measuring the effects of perfusion with the NO synthase inhibitor Nw-nitro-L-arginine-methyl-ester (L-NAME) (100 micromol/L) on Lp (n = 6). In addition, Lp measured after a 15-minute perfusion with L-NAME (100 micromol/L) was compared with measures of Lp obtained after perfusion with a combined mixture of L-NAME (100 micromol/L) and ET-1 (80 pmol/L) (n = 6). RESULTS: Units for Lp are mean +/- SE x 10(-8) cm x sec(-1) x cm H2O(-1). Under basal conditions, in the absence of exogenous ET-1, NO synthase inhibition led to a significant increase in Lp from 5.7 +/- 0.5 to 9.8 +/- 1.4 (p = 0.02). Compared with L-NAME alone, ET-1 + L-NAME significantly decreased Lp from 10.3 +/- 0.8 to 5.7 +/- 0.6 (p = 0.006). CONCLUSION: Constitutive release of NO from the microvascular endothelium plays a role in maintaining a basal level of microvascular permeability. Decreases in microvascular permeability seen with the administration of ET-1 are not mediated via the release of NO. These findings suggest important roles for ET-1 and NO in maintaining and modulating microvascular permeability.

Animals↗
PubMed2001

Abdominal ultrasound examination in pregnant blunt trauma patients.

BACKGROUND: The ability of abdominal ultrasound to detect intraperitoneal fluid in the pregnant trauma patient has been questioned. METHODS: Pregnant blunt trauma patients admitted to a Level I trauma center during an 8-year period were reviewed. Ultrasound examinations were used to detect intraperitoneal fluid and considered positive if such fluid was identified. RESULTS: One hundred twenty-seven (61%) of 208 pregnant patients had abdominal ultrasound during initial evaluation in the emergency department. Seven patients had intra-abdominal injuries, and six had documented hemoperitoneum. Ultrasound identified intraperitoneal fluid in five of these six patients (sensitivity, 83%; 95% confidence interval, 36-100%). In the 120 patients without intra-abdominal injury, ultrasound was negative in 117 (specificity, 98%; 95% confidence interval, 93-100%). The three patients without intra-abdominal injury but with a positive ultrasound had the following: serous intraperitoneal fluid and no injuries at laparotomy (one) and uneventful clinical courses of observation (two). CONCLUSION: The sensitivity and specificity of abdominal ultrasonography in pregnant trauma patients is similar to that seen in nonpregnant patients. Occasional false negatives occur and a negative initial examination should not be used as conclusive evidence that intra-abdominal injury is not present. Ultrasound has the advantages of no radiation exposure.

Abdominal Injuries↗
PubMed2001

Penetrating colon injuries requiring resection: diversion or primary anastomosis? An AAST prospective multicenter study.

BACKGROUND: The management of colon injuries that require resection is an unresolved issue because the existing practices are derived mainly from class III evidence. Because of the inability of any single trauma center to accumulate enough cases for meaningful statistical analysis, a multicenter prospective study was performed to compare primary anastomosis with diversion and identify the risk factors for colon-related abdominal complications. METHODS: This was a prospective study from 19 trauma centers and included patients with colon resection because of penetrating trauma, who survived at least 72 hours. Multivariate logistic regression analysis was used to compare outcomes in patients with primary anastomosis or diversion and identify independent risk factors for the development of abdominal complications. RESULTS: Two hundred ninety-seven patients fulfilled the criteria for inclusion and analysis. Overall, 197 patients (66.3%) were managed by primary anastomosis and 100 (33.7%) by diversion. The overall colon-related mortality was 1.3% (four deaths in the diversion group, no deaths in the primary anastomosis group, p = 0.012). Colon-related abdominal complications occurred in 24% of all patients (primary repair, 22%; diversion, 27%; p = 0.373). Multivariate analysis including all potential risk factors with p values < 0.2 identified three independent risk factors for abdominal complications: severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis. The type of colon management was not found to be a risk factor. Comparison of primary anastomosis with diversion using multivariate analysis adjusting for the above three identified risk factors or the risk factors previously described in the literature (shock at admission, delay > 6 hours to operating room, penetrating abdominal trauma index > 25, severe fecal contamination, and transfusion of > 6 units blood) showed no statistically significant difference in outcome. Similarly, multivariate analysis and comparison of the two methods of colon management in high-risk patients showed no difference in outcome. CONCLUSION: The surgical method of colon management after resection for penetrating trauma does not affect the incidence of abdominal complications, irrespective of associated risk factors. Severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis are independent risk factors for abdominal complications. In view of these findings, the reduced quality of life, and the need for a subsequent operation in colostomy patients, primary anastomosis should be considered in all such patients.

Adult↗
PubMed2000

Spontaneous splenic rupture due to subcutaneous heparin therapy.

We report a case of spontaneous splenic rupture in a 59-year-old woman who was receiving 15,000 units of heparin subcutaneously (s.c. ) twice a day for deep venous thrombosis (DVT) prophylaxis. Her past medical history included multiple DVT, pulmonary emboli, and ovarian cancer stage III-C with known ascites. The diagnosis of splenic rupture was initially missed because of the ascites. This case illustrates both a previously undescribed complication of s.c. heparin therapy and a failure of ultrasound diagnosis. We emphasize the unique presentation, difficulty in diagnosis, and need for early surgical involvement to ensure the most favorable outcome.

Anticoagulants↗
PubMed2000

Basal release of endothelin-1 and the influence of the ETB receptor on single vessel hydraulic permeability.

BACKGROUND: Endothelin-1 (ET-1) has a direct permeability decreasing effect on the microvasculature. The present study was designed to test the hypothesis that this effect is mediated via the endothelin B (ETB) receptor located on the microvascular endothelium and to determine whether basal microvascular permeability is dependent on constitutive release of ET-1. To isolate the direct effect of ET-1, experiments were conducted under conditions in which hydraulic and oncotic pressures were controlled. METHODS: Postcapillary venules in the rat mesentery were perfused in situ, and paired measurements of hydraulic permeability (Lp) were obtained using the modified Landis micro-occlusion method. Lp measured after a 15-minute perfusion with the ETB receptor blocker BQ-788 (1 micromol/L) was compared with measures of Lp obtained after perfusion with a combined mixture of BQ-788 and ET-1 (80 pmol/L) (n = 6). In addition, the effect of basal endogenous ET-1 was tested by measuring the effects of BQ-788 perfusion on Lp (n = 6). RESULTS: Units for Lp are mean +/- SE x 10(-8) cm x s(-1) cm H2O(-1). ETB receptor blockade prevented any decrease in Lp induced by ET-1 (BQ-788 alone = 7.9 +/- 0.7; BQ-788 + ET-1 = 8.2 +/- 0.8;p = 0.5). Under basal conditions and in the absence of exogenous ET-1, ETB receptor blockade led to a significant increase in Lp from 6.8 +/- 0.9 to 9.7 +/- 1.2 (p = 0.001). CONCLUSION: Decreases in microvascular permeability in single postcapillary venules after the administration of ET-1 are mediated via the ETB receptor. Constitutive release of ET-1 from the microvascular endothelium also plays a role in maintaining basal levels of permeability. These findings suggest important roles for ET-1 in maintaining and modulating microvascular permeability.

Animals↗
PubMed1999

Methamphetamine use in trauma patients: a population-based study.

BACKGROUND: There are indications that methamphetamine production and illicit use are increasing. We investigated the epidemiology of methamphetamine use in trauma patients in an area of heavy methamphetamine prevalence. STUDY DESIGN: This was a retrospective population-based review. We reviewed toxicology and alcohol test results in trauma patients admitted to the University of California, Davis, between 1989 and 1994 to the only trauma center serving a population of 1.1 million. RESULTS: Positive methamphetamine rates nearly doubled between 1989 (7.4%) and 1994 (13.4%), compared with a minimal increase in cocaine rates (5.8% to 6.2%) and a decrease in blood alcohol rates (43% to 35%). Methamphetamine-positive patients were most likely to be Caucasian or Hispanic; cocaine-positive patients were most likely to be African American. Methamphetamine-positive patients were most commonly injured in motor vehicle collisions or motorcycle collisions; cocaine-positive patients were most commonly injured by assaults, gunshot wounds, or stab wounds. Cocaine positivity and alcohol positivity predicted a decreased need for emergency surgery and cocaine positivity predicted a decreased need for admission to the ICU. CONCLUSIONS: Methamphetamine use in trauma patients increased markedly in our region between 1989 and 1994, alcohol rates decreased, and cocaine rates remained unchanged. Methamphetamine-positive patients had mechanisms of injury similar to those of alcohol-positive patients, so injury prevention strategies for methamphetamine should be patterned after strategies designed for alcohol.

Alcoholic Intoxication↗
PubMed1999

Syncope-related trauma: rationale and yield of diagnostic studies.

BACKGROUND: Syncope occasionally occurs in trauma patients. The most appropriate and cost-effective evaluation for such patients is unknown. METHODS: Trauma patients admitted to a Level I trauma center with a diagnosis of syncope or possible syncope between 1988 and 1994 were reviewed. History, physical examination, and past medical history were noted, as were the results of tests done as part of the syncope evaluation. RESULTS: Eighty-eight patients were reviewed; 45% had been injured in falls. Thirteen patients who remembered their entire injury and denied syncope as a cause had negative evaluations. History, physical examination, and admission laboratory values were helpful in diagnosis 59% of the time. Subsequent evaluation provided useful diagnostic information 30% of the time. No patients with normal admission electrocardiograms (EKGs) had cardiac causes for their syncope. CONCLUSIONS: (1) Patients with possible syncope without loss of consciousness require no further evaluation. (2) A cerebrovascular evaluation should be the initial diagnostic approach in patients with signs and symptoms suggestive of stroke or transient ischemic attack. (3) Possible syncope patients with normal admission EKGs should undergo computed tomography of the head and electroencephalography. Those with abnormal EKGs should undergo echocardiography.

Accidental Falls↗
PubMed1999

Tumor necrosis factor depresses myocardial contractility in endotoxemic swine.

BACKGROUND: Depression of myocardial contractility occurs in septic shock. METHODS: Fourteen pigs were instrumented to measure cardiopulmonary dynamics after a challenge of Escherichia coli endotoxin (lipopolysaccharide endotoxin, LPS). A volumetric Swan-Ganz catheter was placed via the jugular vein, and a carotid arterial line was placed into the aortic root. Eight pigs received LPS alone and six pigs received tumor necrosis factor monoclonal antibody (TNF MAb) 15 minutes before the administration of LPS. Pulmonary artery and aortic root blood were sampled for amounts of TNF. Ninety minutes after LPS administration, thoracotomy was performed to biopsy the right and left ventricles for TNF levels. Contractility was determined from the end systolic pressure-volume relationships of pressure-volume diagrams. RESULTS: Right ventricular end diastolic volume index nearly doubled and myocardial contractility decreased by 40% from baseline in the pigs receiving only LPS. Pigs that received TNF MAb had no change in myocardial contractility or right ventricular end diastolic volume index from baseline. There was a higher level of TNF in the aortic sample than in the pulmonary samples at 60 minutes. Right ventricular tissue TNF levels were significantly higher in the LPS-alone group. There was no such difference in left ventricular tissue. CONCLUSION: The left and right ventricles have different susceptibilities to TNF MAb. TNF may decrease myocardial contractility in sepsis. Blockade of TNF with TNF MAb reverses the depression of myocardial contractility and the right ventricular dilatation associated with septic shock.

Animals↗
PubMed1999

Direct actions of endothelin-1 on single vessel hydraulic permeability.

BACKGROUND: There is evidence that endothelin-1 (ET-1) increases extravasation of fluid and protein into vascular beds. The present study was designed to determine the direct effects of ET-1 on hydraulic permeability (Lp) when microvascular hydraulic and oncotic pressures are controlled. METHODS: Postcapillary venules in the rat mesentery were perfused in situ and paired measurements of Lp obtained by using the modified Landis micro-occlusion method. Lp measured after a 15-minute perfusion with Ringer's albumin solution (control) was compared with Lp after a subsequent 15-minute perfusion with one of three treatments: control (n = 4), 8 pM ET-1 (n = 6), or 80 pM ET-1 (n = 6). RESULTS: Baseline L for all vessels averaged (+/- SE) 8.1 +/-0.8 x 10(-8) cm x sec(-10 x cm H2O(-1) and was not significantly different between groups. Perfusion with either control or 8 pM ET-1 did not significantly change the Lp of any of the vessels. Significant decreases in Lp of 40 to 60% were observed in venules perfused with 80 pM ET-1. The average Lp in this group was 9.9 +/- 1.4 during baseline and decreased to 5.0 +/- 0.7 during ET-1 perfusion (p = 0.003). Washout of 80 pM ET-1 for periods of up to 15 minutes did not return Lp to baseline values. CONCLUSION: Low-dose ET-1 did not directly increase Lp in postcapillary venules. ET-1 at 80 pM, however, significantly decreased Lp. These data implicate factors other than a direct permeability-increasing effect in ET-1. At higher concentrations, ET-1 may have a protective effect on endothelial barrier function.

Analysis of Variance↗
PubMed1998

Isolated transient loss of consciousness is an indicator of significant injury.

OBJECTIVE: To determine if isolated transient loss of consciousness is an indicator of significant injury. SETTING: University-based level I trauma center. DESIGN AND PATIENT: Phase 1 retrospective case series of all patients with trauma admitted directly from the emergency department to the operating room or an intensive care unit who had transient loss of consciousness as their only trauma triage criterion. Phase 2 prospective case series of all trauma patients transported by emergency medical system personnel with transient loss of consciousness as their only trauma triage criterion. MAIN OUTCOME MEASURES: Emergency operation and intensive care unit admission. RESULTS: Phase 1: From January 1, 1992, to March 31, 1995, we admitted 10255 patients with trauma. Three hundred seven (3%) met the enrollment criteria and were admitted to the operating room (n = 168) or intensive care unit (n = 139). Of these, 58 (18.9%) were taken to the operating room emergently to manage life-threatening injuries: 11 (4%) had craniotomies and 47 (15%) had non-neurosurgical operations. Phase 2: From July 1 to December 31, 1996, 2770 trauma patients were transported to our facility; 135 (4.9%) met the enrollment criteria. Forty-one (30.4%) of these required admission, and 6 (4.4%) were taken emergently to the operating room from the emergency department (1 [1%] for a craniotomy, 3 [2.2%] for intra-abdominal bleeding, and 2 [1.5%] for other procedures). Two (1.5%) of the 135 patients died. CONCLUSIONS: Patients with isolated transient loss of consciousness are at significant risk of critical surgical and neurosurgical injuries. These patients should be triaged to trauma centers or hospitals with adequate imaging, surgical, and neurosurgical resources.

Adult↗
PubMed1998

Comparison of gastric mucosal pH and clinical judgement in critically ill patients.

OBJECTIVES: To compare gastric tonometry (pHi) with estimates of pHi in ill injured patients, and to correlate pHi with haemodynamic variables. DESIGN: Prospective, non-interventional study. SETTING: ICU of Level I trauma centre, USA. MAIN OUTCOME MEASURES: 154 gastric tonometry measurements were compared with physicians' estimates of adequacy of resuscitation. Resuscitation was categorised as inadequate (pHi < 7.35) or adequate (pHi> or = 7.35). Measured and estimated pHi were also compared with oxygen delivery, oxygen consumption, cardiac index, mixed venous O2 saturation, and critical illness scores. RESULTS: Estimated pHi was often higher than measured pHi in the judgement of all four surgical intensive care physicians. Measured pHi correlated positively with mixed venous O2 tension (r = 0.21). There were significant negative correlations between measured pHi and both oxygen delivery (r = -0.25) and oxygen consumption (r = 0.28). Estimated pHi correlated positively with mean arterial pressure (r = 0.21) and hospital day (r = 0.26); it correlated negatively with pulmonary arterial elastance (r = -0.35). CONCLUSION: Experienced intensive care physicians tended to overestimate visceral perfusion, which suggests that gastric tonometry adds useful information over and above routine haemodynamic indices. Arterial blood pressure and mixed venous oxygen saturation correlated better with measured pHi than with other indices of perfusion.

Adolescent↗
PubMed1997

Hemodynamic and metabolic effects of vasopressin blockade in endotoxin shock.

BACKGROUND: Arginine vasopressin V1 receptor antagonist (AVPRA) was administered to investigate the influence of vasopressin blockade on hemodynamics and metabolism during endotoxin shock. METHODS: Anesthetized rats were divided into four groups: control (0.9% saline solution, n = 5), drug control (AVPRA, n = 5), endotoxin (endotoxin, 5 mg/kg, n = 10), and pretreatment (AVPRA and endotoxin, n = 10). Hemodynamics and oxygen transport were evaluated for 2 hours. Terminal arterial and portal venous concentrations of endotoxin, pyruvate, lactate, and ketone bodies were determined. RESULTS: The endotoxin group maintained blood pressure levels similar to those of control animals. AVPRA pretreatment decreased vascular resistance and resulted in lower blood pressure than endotoxin alone. Endotoxin decreased oxygen consumption and the oxygen extraction ratio and increased arterial lactate concentration and the lactate/pyruvate ratio. Endotoxin also decreased arterial ketone body concentration and markedly decreased ketone body availability in the mesenteric circulation. AVPRA pretreatment improved oxygen consumption, oxygen extraction ratio, and ketone body availability; arterial lactate concentration, lactate/pyruvate ratio, and arterial ketone body concentration were not affected. Pretreatment with AVPRA also decreased arterial and portal venous concentrations of endotoxin. CONCLUSIONS: Vasopressin receptor blockade during endotoxemia resulted in lower blood pressure than endotoxin alone. Vasopressin receptor blockade also maintained oxygen extraction ratio and ketone body availability in the mesenteric circulation. Vasopressin may play a key role in the response to endotoxemia.

Animals↗
PubMed1997

Effect of oral contrast administration for abdominal computed tomography in the evaluation of acute blunt trauma.

STUDY OBJECTIVE: To determine how frequently oral contrast medium (OC) is essential for computed tomography (CT) diagnosis of blunt intraabdominal injury and to quantify the delay associated with OC administration and the incidence of adverse effects. METHODS: This retrospective chart review, with prospective reevaluation of CT scans for diagnostic value of OC, took place in a university teaching hospital and Level l trauma center. Participants were blunt-trauma victims admitted between June 1, 1988, and November 1, 1993, who had abdominal CT as part of their initial evaluation. Trauma registry records were used to identify study patients. Available charts and CTs were reviewed for all patients with intestinal/mesenteric and pancreatic injuries. Randomly selected cases of liver injury, spleen injury, and no intraabdominal injury were also reviewed. Blinded CT scans were reevaluated for quality of bowel opacification and value of OC to diagnostic impression. RESULTS: During the study period, 2,162 blunt-trauma patients had an abdominal CT; 297 intraabdominal injuries were diagnosed in 248 patients. Full review was done on 124 charts, and 70 CT scans were reevaluated. Thirty-one (100%) of 31 liver and spleen injuries were diagnosed on CT, and OC was considered essential in none of these studies. One (4.5%) of 22 intestinal and mesenteric injuries was seen on CT, but this was the only such injury treated nonoperatively. None of 21 surgically confirmed intestinal/mesenteric injuries was seen on CT. Free air or free OC was seen in none of 7 cases of intestinal perforation. OC was judged essential in none of 20 scans in patients without intraabdominal injury. On 2 scans. OC was considered essential for the radiographic diagnosis. One of these was a normal pancreas at exploration (radiographic false-positive result). The only pancreatic injury requiring specific surgical treatment was missed on CT. Twenty-one percent of patients required placement of nasogastric tube for contrast administration after failing oral administration, and 23% vomited OC. One of 124 had documented aspiration of OC. Average additional time incurred in the ED for administration of OC was 144 minutes. CONCLUSION: OC is rarely essential for CT diagnosis of intraabdominal injury. It may improve sensitivity for pancreatic injury, but it does not help identify injuries requiring surgical treatment. Even with OC, CT is insensitive for intestinal injury. Vomiting and aspiration are significant risks. Use of OC adds a significant amount of time to ED evaluation. Adverse effects of OC administration, in this setting, may outweigh its benefits.

Abdominal Injuries↗
PubMed1997

Prospective study of blunt aortic injury: Multicenter Trial of the American Association for the Surgery of Trauma.

BACKGROUND: Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years. METHODS: This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma. RESULTS: There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia. CONCLUSIONS: Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.

Adolescent↗
PubMed1997

Initial small-volume hypertonic resuscitation of shock and brain injury: short- and long-term effects.

BACKGROUND: Initial small-volume hypertonic saline resuscitation of a combined hemorrhagic shock and head injury model was studied. METHODS: Twenty-three sheep underwent hemorrhage (20 mL/kg) and parietal freeze injury followed by initial bolus resuscitation with lactated Ringer's solution (40 mL/kg) or 7.5% hypertonic saline (HS) (4 mL/kg). Cardiac index was maintained with lactated Ringer's solution for either 2 or 24 hours. Parietal lobe water content, blood volume, and blood flow were determined. Intracranial pressure (millimeters of mercury) was followed. RESULTS: Overall fluid requirements (milliliters per kilogram) were less at 2 and 24 hours with HS resuscitation. Early intracranial pressure was less with HS resuscitation. Brain water contents were similar between groups. Blood flow in injured and blood volume in uninjured parietal lobe were less for HS at 2 hours, although not different at 24 hours. CONCLUSIONS: Less fluid was needed in the short- and long-term with HS resuscitation. Early intracranial pressure was higher with lactated Ringer's solution resuscitation, possibly in part owing to increased blood volume.

Animals↗