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Biomedical subjects

S M Cohn

Publications and source records attributed to S M Cohn.

At least 19 recordsLinked to original sources
PubMed2002

Prospective study of the incidence and outcome of intra-abdominal hypertension and the abdominal compartment syndrome.

BACKGROUND: Intra-abdominal hypertension has been recognized as a source of morbidity and mortality in the traumatized patient following laparotomy. Multiple organ dysfunction attributable to intra-abdominal hypertension has been called the abdominal compartment syndrome. The epidemiology and characteristics of these processes remain poorly defined. METHODS: Intra-abdominal pressure was measured prospectively in all patients admitted to a trauma intensive care unit over 9 months. Data were gathered on all patients with intra-abdominal hypertension. RESULTS: Some 706 patients were evaluated. Fifteen (2 per cent) of 706 patients had intra-abdominal hypertension. Six of the 15 patients with intra-abdominal hypertension had abdominal compartment syndrome. Half of the patients with abdominal compartment syndrome died, as did two of the remaining nine patients with intra-abdominal hypertension. Patients with abdominal compartment syndrome had a mean intra-abdominal pressure of 42 mmHg compared with 26 mmHg in patients with intra-abdominal hypertension only (P < 0.05). CONCLUSION: The incidence of intra-abdominal hypertension and abdominal compartment syndrome was 2 and 1 per cent respectively. Intra-abdominal hypertension did not necessarily lead to abdominal compartment syndrome, and often resolved without clinical sequelae. Abdominal compartment syndrome did not occur in the absence of earlier laparotomy. Abdominal compartment syndrome was associated with a marked increase in intra-abdominal pressure (above 40 mmHg).

Adolescent↗
PubMed2001

Cost-utility of initial medical management for Crohn's disease perianal fistulae.

BACKGROUND & AIMS: The cost-utility of infliximab is unknown. The aim of this study was to determine the incremental cost-utility (CU(inc)) of medical therapy for Crohn's disease (CD) perianal fistula. METHODS: A Markov model was used to simulate a 1-year treatment period with the following: 6-mercaptopurine and metronidazole [6MP/met] (comparator), 3 infliximab infusions + 6MP/met as second-line therapy (intervention I), infliximab with episodic reinfusion (intervention II), and 6MP/met + infliximab as second-line therapy (intervention III). Utilities were elicited from patients with CD and healthy individuals by standard gamble, and costs were obtained from hospital billing data. Uncertainty was assessed by sensitivity analysis. RESULTS: All strategies had similar effectiveness. Interventions I, II, and III were slightly more effective, but also more costly than 6MP/met (Intervention I: CU(inc) = $355,450/quality-adjusted life-years [QALY]; Intervention II: CU(inc) = $360,900/QALY; Intervention III: CU(inc) = $377,000/QALY). If the cost of infliximab were reduced to $304 per infusion, the CU(inc) for intervention II would be $54,050/QALY. CONCLUSIONS: Based on available data, all strategies had similar effectiveness in our model, but infliximab was much more expensive than 6MP/met. The incremental benefit of infliximab for treating CD perianal fistulae over a 1-year period may not justify the higher cost. Prospective studies directly comparing 6MP/met and infliximab are warranted.

Adult↗
PubMed2001

Near-infrared spectroscopy reflects changes in mesenteric and systemic perfusion during abdominal compartment syndrome.

BACKGROUND: Continuous and minimally invasive near-infrared spectroscopy (NIRS)-derived gastric tissue oxygen saturation (GStO(2)) and muscle tissue oxygen saturation (MStO(2)) were evaluated in a clinically relevant porcine model of hemorrhagic shock and abdominal compartment syndrome (ACS). METHODS: Phenobarbital-anesthetized swine underwent pulmonary artery catheter insertion for mixed venous oxygen saturation (SvO(2)) measurement and midline laparotomy to permit placement of a gastric NIRS probe, a jejunal (regional carbon dioxide [PrCO(2)]) tonometer, superior mesenteric artery (SMA) flow probe, and a portal vein oxygen saturation (SpvO(2)) catheter. A muscle NIRS probe was placed on the front limb. After randomization, Group 1 underwent hemorrhage and resuscitation. Group 2 had no hemorrhage or resuscitation. ACS was induced by peritoneal fluid infusion in both groups. A significant decrease in SMA flow, SpvO(2), GStO(2), SvO(2), and MStO(2) was observed after hemorrhage in Group 1 and with abdominal hypertension in both groups. RESULTS: GStO(2) significantly correlated with SMA flow (Group 1: r(2) = 0.90; Group 2: r(2) = 0.83) and mesenteric oxygen delivery (mesenteric oxygen delivery, Group 1: r(2) = 0.73; Group 2: r(2) = 0.89). MStO(2) significantly correlated with SvO(2) (Group 1: r(2) = 0.99; Group 2: r(2) = 0.65) and systemic oxygen delivery (SDO2, Group 1: r(2) = 0.60; Group 2: r(2) = 0.88). Tonometer-derived PrCO(2) values did not change at any time point in either group. CONCLUSIONS: NIRS measurement of GStO(2) and MStO(2) reflected changes in mesenteric and systemic perfusion respectively during hemorrhage and ACS.

Abdomen↗
PubMed2001

Prospective randomized trial of two wound management strategies for dirty abdominal wounds.

OBJECTIVE: To determine the optimal method of wound closure for dirty abdominal wounds. SUMMARY BACKGROUND DATA: The rate of wound infection for dirty abdominal wounds is approximately 40%, but the optimal method of wound closure remains controversial. Three randomized studies comparing delayed primary closure (DPC) with primary closure (PC) have not conclusively shown any advantage of one method over the other in terms of wound infection. METHODS: Fifty-one patients with dirty abdominal wounds related to perforated appendicitis, other perforated viscus, traumatic injuries more than 4 hours old, or intraabdominal abscesses were enrolled. Patients were stratified by cause (appendicitis vs. all other causes) and prospectively randomized to one of two wound management strategies: E/DPC (wound packed with saline-soaked gauze, evaluated 3 days after surgery for closure the next day if appropriate) or PC. In the E/DPC group, wounds that were not pristine when examined on postoperative day 3 were not closed and daily dressing changes were instituted. Wounds were considered infected if purulence discharged from the wound, or possibly infected if signs of inflammation or a serous discharge developed. RESULTS: Two patients were withdrawn because they died less than 72 hours after surgery. The wound infection rate was greater in the PC group than in the E/DPC group. Lengths of hospital stay and hospital charges were similar between the two groups. CONCLUSION: A strategy of DPC for appropriate dirty abdominal wounds 4 days after surgery produced a decreased wound infection rate compared with PC without increasing the length of stay or cost.

Abdominal Abscess↗
PubMed2001

2,576 ultrasounds for blunt abdominal trauma.

BACKGROUND: Determination of intra-abdominal injury following blunt abdominal trauma (BAT) continues to be a diagnostic challenge. Ultrasound (US) has been described as a potentially useful diagnostic tool in this setting and is being used with increasing frequency in trauma centers. We determined the diagnostic capability of US in the evaluation of BAT. METHODS: A retrospective analysis of our trauma US database was performed over a 30-month period. Computed tomographic scan, diagnostic peritoneal lavage, or exploratory laparotomy confirmed the presence of intra-abdominal injury. RESULTS: During the study period, 8,197 patients were evaluated at the Ryder Trauma Center. Of this group, 2,576 (31%) had US in the evaluation of BAT. Three hundred eleven (12%) US exams were considered positive. Forty-three patients (1.7%) had a false-negative US; of this group, 10 (33%) required exploratory laparotomy. US had a sensitivity of 86%, a specificity of 98%, and an accuracy of 97% for detection of intra-abdominal injuries. Positive predictive value was 87% and negative predictive value was 98%. CONCLUSION: Emergency US is highly reliable and may replace computed tomographic scan and diagnostic peritoneal lavage as the initial diagnostic modality in the evaluation of most patients with BAT.

Abdominal Injuries↗
PubMed2001

Splanchnic perfusion evaluation during hemorrhage and resuscitation with gastric near-infrared spectroscopy.

OBJECTIVE: The purpose of this study was to use a prototype side-illuminating near-infrared spectroscopy (NIRS) nasogastric probe to continuously measure changes in gastric tissue oxygen saturation (Sto2) in a pig hemorrhage model. METHODS: Swine (n = 12; 6 per group) underwent laparotomy and placement of a gastric NIRS probe, jejunal tonometer, superior mesenteric artery (SMA) flow probe, and a portal vein catheter. Animals underwent hemorrhage (28 mL/kg) t = 0 to 20 minutes (where t = time). Pigs in group I were resuscitated (t = 20-40 minutes) with lactated Ringer's solution (84 mL/kg), whereas group II had no resuscitation. RESULTS: A significant decrease in mean arterial pressure and SMA flow was observed after hemorrhage. SMA flow significantly correlated in group I with both NIRS Sto2 (r = 0.58, p = 0.0001) and regional CO2 (r = -0.54, p = 0.0001). In group II, superior mesenteric flow correlated with NIRS Sto2 (r = 0.30, p = 0.03), but not regional CO2 (r = -0.23, p = 0.09). CONCLUSION: Direct measurement of tissue oxygen saturation with a prototype side-illuminating near-infrared spectroscopy gastric probe appeared to rapidly reflect changes in splanchnic perfusion.

Analysis of Variance↗
PubMed2001

Hemoperitoneum score helps determine need for therapeutic laparotomy.

PURPOSE: Sonography provides a fast, portable, and noninvasive method for patient assessment. However, the benefit of providing real-time ultrasound (US) imaging and fluid quantification shortly after patient arrival has not been explored. The objective of this study was to prospectively validate a US hemoperitoneum scoring system developed at our institution and determine whether sonography can predict a therapeutic operation. METHODS: For 12 months, prospective data on all patients undergoing a trauma sonogram were recorded. All sonograms positive for free fluid were given a hemoperitoneum score. The US score was compared with initial systolic blood pressure and base deficit to assess the ability of sonography to predict a therapeutic laparotomy. RESULTS: Forty of 46 patients (87%) with a US score > or = 3 required a therapeutic laparotomy. Forty-six of 54 patients with a US score < 3 (85%) did not need operative intervention. The sensitivity of sonography was 83% compared with 28% and 49% for systolic blood pressure and base deficit, respectively, in determining the need for therapeutic operation. CONCLUSION: We conclude that the majority of patients with a score > or = 3 will need surgery. The US hemoperitoneum scoring system was a better predictor of a therapeutic laparotomy than initial blood pressure and/or base deficit.

Abdominal Injuries↗
PubMed2001

Characterization of a human plasma membrane heme transporter in intestinal and hepatocyte cell lines.

Heme is the most bioavailable form of dietary iron and a component of many cellular proteins. Controversy exists as to whether heme uptake occurs via specific transport mechanisms or passive diffusion. The aims of this study were to quantify cellular heme uptake with a fluorescent heme analog and to determine whether heme uptake is mediated by a heme transporter in intestinal and hepatic cell lines. A zinc-substituted porphyrin, zinc mesoporphyrin (ZnMP), was validated as a heme homolog in uptake studies of intestinal (Caco-2, I-407) and hepatic (HepG2) cell lines. Uptake experiments to determine time dependence, heme inhibition, concentration dependence, temperature dependence, and response to the heme synthesis inhibitor succinylacetone were performed. Fluorescence microscope images were used to quantify uptake and determine the cellular localization of ZnMP; ZnMP uptake was seen in intestinal and hepatic cell lines, with cytoplasmic uptake and nuclear sparing. Uptake was dose- and temperature dependent, inhibited by heme competition, and saturated over time. Preincubation with succinylacetone augmented uptake, with an increased initial uptake rate. These findings establish a new method for quantifying heme uptake in individual cells and provide strong evidence that this uptake is a regulated, carrier-mediated process.

Carrier Proteins↗
PubMed2001

Evaluating blunt abdominal trauma with sonography: a cost analysis.

Ultrasonography (US) is becoming increasingly utilized in the United States for the evaluation of blunt abdominal trauma (BAT). The objective of this study was to assess the cost impact of utilizing US in the evaluation of patients with BAT in a major trauma center. All patients sustaining BAT during a 6-month period before US was used at our institution (Jan-Jun 1993) were compared to BAT patients from a recent period in which US has been utilized (Jan-Jun 1995). The numbers of US, computed tomography (CT), and diagnostic peritoneal lavage (DPL) were tabulated for each group. Financial cost for each of these procedures as determined by our finance department were as follows: US $96, CT $494, DPL $137. These numbers are representative of actual hospital expenditures exclusive of physician fees as calculated in 1994 U.S. dollars. Cost analysis was performed with t test and chi squared test, and significance was defined as P < 0.05. There were 890 BAT admissions in the 1993 study period and 1033 admissions in the 1995 study period. During the 1993 period, 642 procedures were performed on the 890 patients to evaluate the abdomen: 0 US, 466 CT, and 176 DPL (see table) [table: see text]. This compares to 801 procedures on the 1,033 patients in 1995: 552 US, 228 CT, and 21 DPL. Total cost was $254,316 for the 1993 group and $168,501 for the 1995 group. Extrapolated to a 1-year period, a significant (P < 0.05) cost savings of $171,630 would be realized. Cost per patient evaluated was significantly reduced from $285.75 in 1993 to $163.12 in 1995 (P < 0.05). This represents a 43 per cent reduction in per patient expenditure for evaluating the abdomen. By effectively utilizing ultrasonography in the evaluation of patients with blunt abdominal trauma, a significant cost savings can be realized. This effect results chiefly from an eight-fold reduction in the use of DPL, and a two-fold reduction in the use of CT.

Abdominal Injuries↗
PubMed2000

Gram positive infection in trauma patients: new strategies to decrease emerging Gram-positive resistance and vancomycin toxicity.

Bacterial resistance to antibiotics has become a serious problem in medicine. Particularly worrisome is the increasing incidence of multi-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Not surprisingly, in view of the high incidence of life-threatening infections and heavy antibiotic use, resistance has become very frequent and problematic in intensive care units. The standard approach for the treatment of MRSA is vancomycin or teicoplanin. Long-term therapeutic and unrestricted prophylactic use of vancomycin has given rise to VRE which in turn may lead to the emergence of vancomycin-resistant S. aureus (VRSA) through plasmid mediated transmission. In order to reduce the incidence of VRE and to avoid the emergence of VRSA, vancomycin use should be restricted and alternative antibiotic strategies should be developed. Using those antibiotics to which MRSA are still generally sensitive, perhaps in combination with new ones, such as, quinupristin/dalfopristin, should be entertained. We performed a retrospective review of the Gram-positive infections in our Level 1 Trauma Center Intensive Care Unit, and an analysis of the resistance patterns of the NMSA infections showed that additional resistance rarely develops within less than 5 days. We then designed a new strategy for the treatment of MRSA infections. This strategy consists of the sequential use of a range of antibiotics with activity against MRSA in short 5-7 day pulses until the full clinical course is completed. Studies validating the benefit of this approach are currently in preparation.

Anti-Bacterial Agents↗
PubMed2000

Neurobehavioural outcomes of penetrating and tangential gunshot wounds to the head.

OBJECTIVE: The objective of this study was to compare penetrating and tangential gunshot wounds to the head with regards to demographic, neurobehavioural and clinical outcome measures. METHODS: Twenty-nine patients with penetrating gunshot wounds (P-GSW) and 11 patients with tangential gunshot wound (T-GSW) to the head admitted to an acute neurotrauma service were compared using standardized neurobehavioural and clinical outcome measures. RESULTS: The mean GCS was 10.5 +/- 0.79 for the P-GSW group and 13.4 +/- 0.72 for the T-GSW group. The mean AIS-CNS for the P-GSW group was 5.00 +/- 0 and for the T-GSW group was 3.7 +/- 0.27. Significance was found on Digit Span (p < 0.05) and Block Design (p < 0.009) subtests. Outcomes between the two groups were similar, except for significant differences were found for acute length of stay (LOS) (P-GSW was 47.72 +/- 13.2 and T-GSW group was 13.0 +/- 1.3, p = 0.005) and for acute care charges (P-GSW group was $150,533 +/- 23,834 and T-GSW group was $70,712 +/- 16,587, p = 0.05). CONCLUSIONS: Initially, a penetrating gunshot wound is a more severe and costly injury than a tangential gunshot wound to the head, however T-GSW possess significant deficits and, if the patient survives past the acute phase of recovery, the two groups have similar functional outcomes. Future standard classification, neuropsychological, and clinical outcome measures.

Adult↗
PubMed2000

Pharmacokinetics and burn eschar penetration of intravenous ciprofloxacin in patients with major thermal injuries.

Adequate penetration of antibiotics into burn tissue and maintenance of effective serum levels are essential for the treatment of patients sustaining major thermal injuries. The pharmacokinetics and burn eschar penetration of intravenous ciprofloxacin were determined in 12 critically ill patients with burn injuries. Mean age for the 12 patients was 45 +/- 17 (range 25-82 years), total body surface area burned (TBSAB) = 38 +/- 15% and Acute Physiology and Chronic Health Evaluation (APACHE) II score = 8 +/- 6. Patients received recommended doses of ciprofloxacin, 400 mg q12h iv, for three doses beginning 72 h post-burn. Serum concentrations were measured at t = 0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 2.0, 4.0 and 12.0 h after the first and third doses. Burn eschar biopsies were obtained after the third ciprofloxacin dose. Three of these 12 patients (25%) manifested later signs of clinical sepsis (TBSAB = 61 +/- 6% and APACHE II score = 11 +/- 3) and underwent a second infusion of three doses of intravenous ciprofloxacin, blood sampling and eschar biopsy. Serum and eschar concentrations were determined by high performance liquid chromatography. Serum ciprofloxacin concentrations were comparable to those of normal volunteers (C(max) = 4.0 +/- 1 mg/L and AUC = 11.4 +/- 2 mg.h/L) during the immediate post-burn period after dose 1 (C(max1) = 4.8 +/- 3 mg/L and AUC(0-12) = 12.5 +/- 7 mg. h/L) and dose 3 (C(max3) = 4.9 +/- 2 mg/L and AUC(24-36) = 17.5 +/- 11 mg.h/L). Mean burn eschar concentration during the 72 h post-burn was significantly lower than that found during clinical sepsis (18 +/- 17 compared with 41.3 +/- 54 microg/g; P < 0.05 by t test). Similar serum concentrations were achieved in patients with clinical sepsis (C(max1) = 4.2 +/- 0.2 mg/L and AUC(0-12) = 15.0 +/- 3 mg. h/L; C(max3) = 5.0 +/- 1 mg/L and AUC(24-36) = 22.8 +/- 9 mg.h/L). A positive correlation between burn eschar concentrations and C(max) (r = 0.71, r(2) = 0.51, P = 0.01) was found by linear regression analysis. A C(max)/MIC ratio > 10 (MIC = 0.5 mg/L) and an AUC/MIC ratio > 100 SIT(-1).h (serum inhibitory titre) (MIC = 0.125 mg/L) were achieved. High burn eschar concentrations and serum levels, similar to those found in normal volunteers, can be achieved after intravenous ciprofloxacin infusion in critically ill burns patients.

Adult↗
PubMed2000

Comparison of intravenous/oral ciprofloxacin plus metronidazole versus piperacillin/tazobactam in the treatment of complicated intraabdominal infections.

OBJECTIVE: To compare the safety and efficacy of intravenous (IV) ciprofloxacin plus IV metronidazole (CIP+MET) with that of IV piperacillin/tazobactam (PIP/TAZO) in adults with complicated intraabdominal infections, and to compare the efficacy of sequential IV-to-oral CIP+MET therapy with that of the IV CIP-only regimen. SUMMARY BACKGROUND DATA: Treatment of intraabdominal infections remains a challenge, mainly because of their polymicrobial etiology and attendant death and complications. Antimicrobial regimens using sequential IV-to-oral therapy may reduce the length of hospital stay. METHODS: In this multicenter, randomized, double-blind trial involving 459 patients, clinically improved IV-treated patients were switched to oral therapy after 48 hours. Overall clinical response was the primary efficacy measurement. RESULTS: A total of 282 patients (151 CIP+MET, 131 PIP/TAZO) were valid for efficacy. Of these patients, 64% CIP+MET and 57% PIP/TAZO patients were considered candidates for oral therapy. Patients had a mean APACHE II score of 9.6. The most common diagnoses were appendicitis (33%), other intraabdominal infection (29%), and abscess (25%). Overall clinical resolution rates were statistically superior for CIP+MET (74%) compared with PIP/TAZO (63%). Corresponding rates in the subgroup suitable for oral therapy were 85% for CIP+MET and 70% for PIP/TAZO. Postsurgical wound infection rates were significantly lower in CIP+MET (11%) versus PIP/TAZO patients (19%). Mean length of stay was 14 days for CIP+MET and 17 days for PIP/TAZO patients. CONCLUSION: CIP+MET, initially administered IV and followed by CIP+MET oral therapy, was clinically more effective than IV PIP/TAZO for the treatment of patients with complicated intraabdominal infections.

Abdomen↗
PubMed2000

Utility of near-infrared spectroscopy in the diagnosis of lower extremity compartment syndrome.

OBJECTIVE: To determine the utility of near-infrared spectroscopy in the diagnosis of lower extremity compartment syndrome (CS). METHODS: Nine patients with CS confirmed by physical examination and elevated compartment pressures (64 +/- 17 mm Hg) were evaluated before and after fasciotomy. Control readings were also performed on 33 surgical patients who had no evidence of CS. The deltoid muscle was used as a reference value. RESULTS: The deltoid muscle oxygen saturation (StO2) readings revealed a mean = 84 +/- 17% prefasciotomy and mean = 83 +/- 12% postfasciotomy in the CS group. The control group had a mean StO2 of 83 +/- 11%. In the CS group, the leg compartment with the highest pressure had a StO2 mean = 56 +/- 27% before fasciotomy. This value was statistically significantly lower (p < 0.05) than either the postfasciotomy mean StO2 in that compartment (82 +/- 16%) or the values found in matched control patients with no evidence of CS (87 +/- 7%). CONCLUSION: Near-infrared spectroscopy-derived StO2 values in the lower extremities of trauma patients with CS were diminished relative to the control patients and usually normalized after fasciotomy. Near-infrared spectroscopy evaluation may offer a rapid, noninvasive method of assessing extremities at risk for CS.

Adult↗
PubMed2000

Identification of trauma patients at risk of thoracic aortic tear by mechanism of injury.

OBJECTIVE: We sought to identify potential measurable on-scene information that would assist clinicians in the identification of patients at risk for thoracic aortic tear (AT) after vehicular trauma. METHODS: Data were prospectively collected at the scene of 295 motor vehicle crashes from 1995 to 1999. There were 34 cases (12%) with AT. Scene data consisted of vehicle maximal crush, maximal intrusion into the occupant compartment, change in velocity (Delta V) and principal direction of force. Thoracic aortic injuries were confirmed radiographically or at autopsy. Crash factors were analyzed for correlation with AT by logistic regression. RESULTS: Delta V > or = 20 mph and near-side impact were the factors having the strongest correlation with thoracic aortic injury. Delta V > or = 20 mph (n = 32 with AT) had an odds ratio = 6.4, (p < 0.01). Near impact (n = 20 with AT) had an odds ratio = 2.3, (p < 0.05) and intrusion > or = 15 inches had an odds ratio = 3.2, p < 0.05. The sensitivity, specificity, and accuracy of the presence of near impact, Delta V > or = 20 mph, or both, were 100%, 34%, and 64%. The positive and negative predictive values were 16% and 100%, respectively. There was no relationship of AT to use of seat belts or airbags. CONCLUSION: Thoracic aortic injury after vehicular collision can be reliably excluded if near-impact, Delta V > or = 20 mph, or intrusion > or = 15 inches are not present. Mechanism of injury in the form of crash scene information may aid clinicians in identifying individuals at risk for thoracic aortic tear after vehicular trauma.

Accidents, Traffic↗