Cardiopulmonary function after pulmonary contusion and partial liquid ventilation.

PURPOSE: To compare the effects of mechanical ventilation with either positive end-expiratory pressure (PEEP) or partial liquid ventilation (PLV) on cardiopulmonary function after severe pulmonary contusion. METHODS: Mongrel pigs (32 +/- 1 kg) were anesthetized, paralyzed, and mechanically ventilated (8-10 mL/kg tidal volume; 12 breaths/min; FiO2 = 0.5). Systemic hemodynamics and pulmonary function were measured for 7 hours after a captive bolt gun delivered a blunt injury to the right chest. After 5 hours, FiO2 was increased to 1.0 and either PEEP (n = 7) in titrated increments to 25 cm H2O or PLV with perflubron (LiquiVent, 30 mL/kg, endotracheal) and no PEEP (n = 7) was administered for 2 hours. Two control groups received injury without treatment (n = 6) or no injury with PLV (n = 3). Fluids were liberalized with PEEP versus PLV (27 +/- 3 vs. 18 +/- 2 mL.kg-1.h-1) to maintain cardiac filling pressures. RESULTS: Before treatment at 5 hours after injury, physiologic dead space fraction (30 +/- 4%), pulmonary vascular resistance (224 +/- 20% of baseline), and airway resistance (437 +/- 110% of baseline) were all increased (p < 0.05). In addition, PaO2/FiO2 had decreased to 112 +/- 18 mm Hg, compliance was depressed to 11 +/- 1 mL/cm H2O (36 +/- 3% of baseline), and shunt fraction was increased to 22 +/- 4% (all p < 0.05). Blood pressure and cardiac index remained stable relative to baseline, but stroke index and systemic oxygen delivery were depressed by 15 to 30% (both p < 0.05). After 2 hours of treatment with PEEP versus PLV, PO2/FiO2 was higher (427 +/- 20 vs. 263 +/- 37) and dead space ventilation was lower (4 +/- 3 vs. 28 +/- 7%) (both p < 0.05), whereas compliance tended to be higher (26 +/- 2 vs. 20 +/- 2) and shunt fraction tended to be lower (0 +/- 0 vs. 7 +/- 4). With PEEP versus PLV, however, cardiac index, stroke index, and systemic oxygen delivery were 30 to 60% lower (all p < 0.05). Furthermore, although contused lungs showed similar damage with either treatment, the secondary injury in the contralateral lung (as manifested by intra-alveolar hemorrhage) was more severe with PEEP than with PLV. CONCLUSIONS: Both PEEP and PLV improved pulmonary function after severe unilateral pulmonary contusion, but negative hemodynamic and histologic changes were associated with PEEP and not with PLV. These data suggest that PLV is a promising novel ventilatory strategy for unilateral pulmonary contusion that might ameliorate secondary injury in the contralateral uninjured lung.

Dehydroepiandrosterone, an endogenous immune modulator, after traumatic shock.

Dehydroepiandrosterone (DHEA), an endogenous immune modulator, reduces mortality after endotoxin (lipopolysaccharide (LPS)) administration in rodents. However, there have been no studies in clinically relevant large-animal models. A unique experimental model is used to study the effects of DHEA in resuscitated trauma and to evaluate the protective effect of DHEA on the systemic inflammatory response induced by a delayed LPS challenge. Anesthetized, ventilated pigs were instrumented and then subjected to local hind-limb trauma and 35% hemorrhage. After 1 h, animals were resuscitated with shed blood, supplemental Ringers solution, and in a randomized, blinded fashion, 4 mg/kg of DHEA or vehicle. Two additional groups received 10 mg/kg or 20 mg/kg of DHEA. Animals were dosed again at 24, 48, and 72 h. After 75 h, Escherichia coli LPS was administered. LPS caused a fall in DHEA levels (0.23 +/- .05 ng/mL (60 min post-LPS) versus .94 +/- 35 ng/mL (72 h), p = .01). DHEA levels 60 min post-LPS were significantly higher in treated animals (p < .002). After LPS, all groups manifested progressive septic symptoms with a hyperdynamic state and pulmonary failure. These symptoms were not blunted by the administration of DHEA. DHEA levels are suppressed by LPS in this two-stage model of trauma and delayed sepsis; however, exogenous DHEA administration fails to blunt the associated systemic inflammatory response and pulmonary failure.

A randomized trial of isonitrogenous enteral diets after severe trauma. An immune-enhancing diet reduces septic complications.

OBJECTIVE: The authors randomized patients to an enteral diet containing glutamine, arginine, omega-3 fatty acids, and nucleotides or to an isonitrogenous, isocaloric diet to investigate the effect of septic outcome. A third group of patients, without enteral access but eligible by severity of injury, served as unfed controls and were studied prospectively to determine the risk of infection. SUMMARY BACKGROUND DATA: Laboratory and clinical studies suggest that diets containing specialty nutrients, such as arginine, glutamine, nucleotides, and omega-3 fatty acids, reduce septic complications. Unfortunately, most clinical trials have not compared these diets versus isonitrogenous, isocaloric controls. This prospective, blinded study randomized 35 severely injured patients with an Abdominal Trauma Index > or = 25 or a Injury Severity Score > or = 21 who had early enteral access to an immune-enhancing diet ([IED] Immun-Aid, McGaw, Inc., Irvine, CA; n = 17) or an isonitrogenous, isocaloric diet (Promote [Ross Laboratories, Columbus, OH] and Casec [Mead-Johnson Nutritionals, Evansville, IN]; n = 18) diet. Patients without early enteral access but eligible by severity of injury served as contemporaneous controls (n = 19). Patients were evaluated for septic complications, antibiotic usage, hospital and intensive care unit (ICU) stay, and hospital costs. RESULTS: Two patients died in the treatment group and were dropped from the study. Significantly fewer major infectious complications (6%) developed in patients randomized to the IED than patients in the isonitrogenous group (41%, p = 0.02) or the control group (58%, p = 0.002). Hospital stay, therapeutic antibiotics, and the development of intra-abdominal abscess was significantly lower in patients receiving the IED than the other two groups. This improved clinical outcome was reflected in reduced hospital costs. CONCLUSIONS: An IED significantly reduces major infectious complications in severely injured patients compared with those receiving isonitrogenous diet or no early enteral nutrition. An IED is the preferred diet for early enteral feeding after severe blunt and penetrating trauma in patients at risk of subsequent septic complications. Unfed patients have the highest complication rate.

Empiric monotherapy versus combination therapy of nosocomial pneumonia in trauma patients.

Combination therapy for nosocomial pneumonia with a beta-lactam and aminoglycoside is widely accepted because of synergy and reduction of resistant bacteria. This prospective study of 109 trauma patients (94 blunt, 15 penetrating) with nosocomial pneumonia was performed in consecutive phases. In phase 1, patients were randomized to an anti-pseudomonal third-generation cephalosporin--cefoperazone or ceftazidime. Gentamicin was added to each regimen in phase 2. The mean age of the patients was 37 years, the mean ISS was 31, and there were no differences among the four treatment groups relative to associated injuries. Patients receiving monotherapy had a 56% cure rate compared with 31% for combination therapy (p < 0.04). Persistence rates were similar in these two groups (15% and 20%), but superinfection was significantly higher in the combination group (49% vs. 28%; p < 0.04). The predominant superinfecting organism was methicillin-resistant Staphylococcus aureus (MRSA). Nine patients died (5% monotherapy, 10% combination), and eight had a superinfection. We conclude that monotherapy had a higher cure rate than combination therapy for empiric therapy of pneumonia in our trauma patients. Combination therapy failed because of superinfection (primarily MRSA). Emergence of MRSA may be from host overgrowth or plasmid-mediated induction of resistance, possibly caused by gentamicin.

Sigmoid volvulus. A four-decade experience.

During the 40 years from 1945 to 1984, 159 occurrences of sigmoid volvulus in 140 patients were diagnosed and managed. Treatment modalities gradually evolved from primarily operative decompression in the first 20 years to selective, sigmoidoscopic, nonoperative reduction in the most recent 10-year period. Operative reduction was associated with a 10 per cent mortality, while no deaths were associated with nonoperative reduction. A 60 per cent mortality was noted when gangrenous bowel was present. In the most recent 10-year period, 71 per cent of cases were associated with neuropsychiatric diseases, and one third had a previous episode of sigmoid volvulus. The diagnosis was made on the initial plain abdominal radiograph in 60 per cent, and nonoperative sigmoidoscopic reduction attained in 95 per cent. Following nonoperative reduction, elective resection was performed during the same hospitalization with a 5 per cent mortality. Initial management of sigmoid volvulus should consist of nonoperative attempts at reduction with operative reduction reserved for refractory cases or those with ischemic bowel. Elective resection can be safely performed during the same hospitalization.