Noncompliance of health care workers with universal precautions during trauma resuscitations

BACKGROUND

Universal precautions during resuscitations are mandated by hospital regulations. We documented adherence to universal precautions during trauma resuscitations at our level I trauma center.

METHODS

During trauma resuscitations, a medical student using an elevated viewing platform observed health care workers (HCWs) for the use of barrier precautions (BPs): gloves, masks, gowns, and eyewear. Only HCWs having direct patient contact were included. The purpose of the observation was not disclosed to those being observed.

RESULTS

In 12 resuscitations involving 104 HCWs, none had 100% compliance with BPs. Compliance rates for individual BPs were gloves, 98%; eyewear (any type), 52%; gowns, 38%; masks, 10%; and eyewear (with side protectors), 9%. Resuscitations in which bleeding was observed involved 59 HCWs with 38% compliance; only 2 used full BPs. No difference in compliance rates occurred during the study period.

CONCLUSIONS

Experienced trauma care HCWs are cavalier regarding blood-borne disease exposure risks. Measures to encourage (or force) compliance are needed.

Higher risk of HIV transmission during trauma resuscitations

Despite an appreciation of the potential for blood borne pathogen exposure, compliance of universal precautions is low. While reports of HIV positive rates in trauma patients have varied from 0.15% to 7.8%, the estimated prevalence of HIV in Louisiana is 0.32%. We made use of two unique, complimentary data sources: the Trauma Registry and the HIV/AIDS Reporting System database of known HIV positive patients to estimate the relative prevalence of HIV which may indicate an increase risk of blood borne pathogen transmission to health care workers during trauma resuscitations. In one year, 1031/1159 patients were evaluated from the Trauma Registry Database and 22 similar patients (2.13%) were found in both the Trauma Registry and the HIV/AIDS Reporting System Database. Our prevalence is an indicator of the minimum risk since it is based on only reported cases of HIV and justifies intensification of education and enforcement of the practice of universal precautions.

Evolution in the management of hepatic trauma: a 25-year perspective

OBJECTIVE

To define the changes in demographics of liver injury during the past 25 years and to document the impact of treatment changes on death rates.

SUMMARY BACKGROUND DATA

No study has presented a long-term review of a large series of hepatic injuries, documenting the effect of treatment changes on outcome. A 25-year review from a concurrently collected database of liver injuries documented changes in treatment and outcome.

METHODS

A database of hepatic injuries from 1975 to 1999 was studied for changes in demographics, treatment patterns, and outcome. Factors potentially responsible for outcome differences were examined.

RESULTS

A total of 1,842 liver injuries were treated. Blunt injuries have dramatically increased; the proportion of major injuries is approximately 16% annually. Nonsurgical therapy is now used in more than 80% of blunt injuries. The death rates from both blunt and penetrating trauma have improved significantly through each successive decade of the study. The improved death rates are due to decreased death from hemorrhage. Factors responsible include fewer major venous injuries requiring surgery, improved outcome with vein injuries, better results with packing, and effective arterial hemorrhage control with arteriographic embolization.

CONCLUSIONS

The treatment and outcome of liver injuries have changed dramatically in 25 years. Multiple modes of therapy are available for hemorrhage control, which has improved outcome.

A critical assessment of endpoints of shock resuscitation

Modern hemodynamic therapy is not only the recognition and treatment of hypotension but also the avoidance and treatment of shock in its broadest sense. The major issues include the recognition of hypoperfusion of the body as a whole or its individual tissues and organ systems and the determination of the best endpoints for the treatment of shock. Even if all of the commonly used clinical indicators of shock are "normal," shock on a cellular, tissue, or organ basis may still be present. Whether "organ-specific" assessments, such as gastric tonometry or tissue oxygen tension measurement, are the ultimate answer to this problem remains to be seen. The determination of adequate intravascular volume (preload) continues to present major difficulties in the care of critically ill or injured patients. Although PCWP is frequently helpful, it is not a gold standard. A bedside ultrasonic technique, such as esophageal Doppler sonography, may replace the Swan-Ganz catheter technique in many patients.

Post-treatment dopexamine infusions partially reverse reductions in cranial mesenteric blood flow and mucosal oxygenation induced by hypoxia in newborn piglets

A severe hypoxic insult is known to induce dramatic reductions in newborn intestinal blood flow and is, thus, considered a vector for the development of neonatal intestinal ischemic diseases. Dopexamine (DPX) is a novel synthetic agent that has potent B2-adrenoceptor and dopaminergic activity, the clinical effects of which include an increase in cardiac output and in mesenteric blood flow. Having previously shown that infusion of DPX before hypoxia (HYP) mitigated the reduction in newborn mesenteric blood flow, we sought to define its efficacy when given after an established hypoxic insult. Ultrasonic transit time blood flow probes were placed around the ascending aorta and cranial mesenteric artery of anesthetized, mechanically ventilated 0 to 2-day-old piglets. Small bowel mucosal oxygenation was observed with a tissue oxygen monitoring system. After stabilization, animals were subjected to one of the following: HYP (FIO2 = 0.12) for 60 minutes (n = 12); DPX (5 microg/kg/min) infusion begun 10 minutes after induction of HYP/DPX (n = 11). Almost no alterations in any of the monitored variables were shown in a group (n = 5) of similarly instrumented, untreated animals. In contrast, although both hypoxic piglet groups experienced significant (P < 0.05, analysis of variance) declines from baseline cardiac output, mesenteric blood flow, and mucosal oxygenation, each of these deleterious effects was significantly (P < 0.05) blunted in the DPX-treated animals. During periods of systemic hypoxemia, the reductions in neonatal mesenteric blood flow and oxygenation can be somewhat blunted by DPX. As such, this agent may prove of clinical benefit when an infant is threatened by a hypoxic episode.

Laparoscopic retroperitoneal repair of recurrent postoperative lumbar hernia

A patient who previously underwent an attempt at open mesh repair of a lumbar hernia that occurred following iliac crest bone harvesting was managed successfully by laparoscopic retroperitoneal fixation of the prosthetic material to the iliac crest using bone screws. A review of the literature supports the use of such a novel approach to manage this often vexing problem.

Esophageal Doppler ultrasound monitor versus pulmonary artery catheter in the hemodynamic management of critically ill surgical patients

BACKGROUND

The pulmonary artery (PA) catheter has been used to determine hemodynamic indices; however, it has recently been criticized. This study was undertaken to evaluate an esophageal Doppler monitor (EDM) as a possible replacement for PA catheter in critically ill, mechanically ventilated patients.

METHODS

EDM and PA catheters were placed in patients in the surgical intensive care units (n = 14, 118 matched sets of data). PA catheter and EDM measurements, including corrected flow time (FTc,) a measure of preload, were obtained. Pearson correlation (r) was analyzed to compare PA catheter and EDM measurements, and a nonlinear regression model was used to describe Starling Relationships.

RESULTS

Cardiac output correlated between EDM and PA catheter (r = 0.6; p < 0.001). FTc correlated more strongly with cardiac output than did pulmonary capillary wedge pressure. (FTc: r2 = 0.27; p < 0.001; cardiac output: r2 = 0.04; p = 0.06).

CONCLUSION

Corrected flow time is a better indicator of preload than pulmonary capillary wedge pressures. EDM seems to be at least as useful as PA catheter in managing the hemodynamic status of critically ill surgical patients.

Initial experience with laparoscopic repair of incisional hernias

BACKGROUND

Development of a safe, unobtrusive means to repair the large incisional hernia continues to represent a challenge to surgeons.

METHODS

A retrospective analysis of the first 12 patients who underwent an attempt at laparoscopic repair of an incisional hernia at a single institution was carried out.

RESULTS

Of the 12 attempts at laparoscopic repair, 11 were completed. No serious perioperative morbidity was encountered. During a mean follow-up of 12.5 months, one recurrence (due to a technical shortcoming that has since been overcome) was identified.

CONCLUSIONS

The laparoscopic approach to incisional hernia repair is a safe alternative to open repair of abdominal wall defects.

Current clinical concepts in perioperative anticoagulation

Management of patients with significant risks for thromboembolism in the perioperative period requires consideration of both risks of thromboembolism and risks of anticoagulant therapy. Patients who are receiving warfarin therapy because of recent venous thromboembolism, nonvalvular atrial fibrillation, and mechanical heart valves are at increased risk during the interval when the warfarin is discontinued and when the international normalized ratio is at a subtherapeutic level. In patients with an acute venous thromboembolic event within the past month, the use of intravenous heparin appears to be justified both preoperatively and postoperatively. If the venous thromboembolic event was within the past 2 to 3 months, use of intravenous heparin appears justified in the postoperative period. More than 3 months after an acute episode of venous thrombophlebitis, the relatively low risk of recurrence does not appear to justify the risks of complications from intravenous heparin. Patients with increased risks of arterial embolism, specifically those with nonvalvular atrial fibrillation and mechanical heart valves, are generally not at sufficient risk of arterial embolism to justify use of intravenous heparin during the perioperative subtherapeutic international normalized ratio interval when warfarin is withheld. A potential increased risk of recurrent arterial embolism when the preceding event was within a month suggests that elective surgery should be deferred beyond a month whenever possible in such patients. The use of fixed-dose, subcutaneous low molecular weight heparin has been observed to have advantages over use of unfractionated intravenous heparin both in terms of safety and efficiency. Further refinements in management of patients with significant risks of thromboembolism may occur with increased experience with low molecular weight heparin.

Postburn vitamin C infusions do not alter early postburn edema formation

To determine whether vitamin C would alter burn induced edema accumulation, hind paw venous pressure, lymph flow (QL), and lymph-to-plasma protein ratio (CL/CP) were monitored in groups of 5 dogs before and 4 hours after 1) a 5 sec 100 degrees C or 90 degrees C foot paw scald; 2) intravenous vitamin C given 30 min before or after a 100 degrees C scald; and 3) vitamin C given 30 min after a 90 degrees C scald. Throughout the experiments, hind paw venous pressure was elevated and maintained by outflow restriction until steady state QL and (CL/CP)min were reached. Changes in protein permeability (CL/CP), fluid conductance properties (Kf) of the capillary membrane, and paw weight gain were determined. Compared with preburn values, scald uniformly produced significant (P < .05, ANOVA) increases in QL, CL/CP and Kf. Although preburn infusion of vitamin C significantly (P < .01) attenuated burn-induced increases in paw weight gain (36 +/- 3% vs 19 +/- 4%), neither of the groups that received vitamin C postburn experienced significant modulations in paw weight gain (28 +/- 4% vs 36 +/- 3% in 100 degrees C burn only; 23 +/- 4% vs 28 +/- 3% in 90 degrees C burn only) or in any of the variables used to monitor capillary membrane integrity. Vitamin C infusions initiated after graded scald produced no changes in the burn-induced increases in microvascular permeability or in edema formation measured at the injury site.

Effects of severe hypoxemia on mesenteric blood flow in neonatal piglets

BACKGROUND

The purpose of this work was to determine the effects of hypoxemia on systemic hemodynamic variables and regional conduit arterial blood flows in neonatal piglets.

MATERIALS AND METHODS

Using transit time blood flow probes, cardiac output and cranial mesenteric artery blood flow were monitored in groups of prematurely delivered (90% of term gestational age) and 2-week-old piglets prior to, during, and after exposure to a 30-min hypoxic (FIO2 = 0.12) challenge.

RESULTS

The documented alterations in systemic mean arterial pressure and cardiac output pressure during hypoxia and reoxygenation were consistent with the maturational age of the animals. In response to hypoxia, all animals demonstrated significant reductions in mesenteric blood flow, with returns to baseline levels during the 30-min reoxygenation phase. In still other prematurely delivered piglets, nutrient mesenteric arterial blood flows were measured using in vivo videomicroscopy. The marked hypoxemia-induced decline in mucosal blood flow was reversed by reoxygenation.

CONCLUSIONS

The physiologic mechanisms responsible for neonatal mesenteric vasoactive responsiveness are present in conduit and in nutrient vessels well prior to birth and can be activated by a significant perturbation. These observations are germane insofar as they provide a stable, age-matched acute animal model to study neonatal intestinal ischemic diseases, including necrotizing enterocolitis.

Efficacy of a novel synthetic material to close exposed fascial defects

BACKGROUND

After developing a synthetic composite material (TMS-1) made from a porous polypropylene mesh (placed in apposition to fascia) coated on the "visceral" side with solid polyurethane, we compared its efficacy with that of porous polytetrafluoroethylene, polypropylene, and primary fascial closure when the repairs were left exposed to the environment.

METHODS

We created 1 cm2 abdominal wall defects in each of the four abdominal quadrants of rats (n = 12). We used porous polytetrafluoroethylene, polypropylene, and TMS-1 to repair three defects; the fourth we primarily closed. The skin was left open in all cases, leaving the fascial closures exposed. A second group of rats (n = 24) had the same operation, except that peritonitis was induced using a standard fecal inoculation technique. When the rats were killed 2 weeks later, a "blinded" observer using a standard scale assessed the surface area and severity of adhesions formed.

RESULTS

When compared with the other synthetic materials, the surface area of adhesions formed was significantly less after primary closure in clean conditions; in contaminated conditions, it was less than porous polytetrafluoroethylene, polypropylene, and the same as TMS-1. Furthermore, in contaminated conditions, the severity of adhesions beneath TMS-1 was the same as primary closure and significantly less than those beneath the polypropylene.

CONCLUSION

The overall superiority of TMS-1 over porous polytetrafluoroethylene and polypropylene in septic conditions justifies further experiments to define its long-term efficacy in the repair of large defects.

Lymph isolated from a regional scald injury produces a negative inotropic effect in dogs

Large surface-area burns in patients have been associated with a severe impairment in cardiac performance, as evidenced by a decline in cardiac output. The mechanisms responsible for this profound myocardial dysfunction are largely unknown. We investigated the effects of lymph isolated from the scalded hind limb of dogs on regional myocardial blood flow, coronary vascular reactivity, and contractile performance. Dogs were instrumented with ultrasonic dimension crystals in the myocardium supplied by the left anterior descending (LAD) and by the left circumflex (LCx) coronary arteries. After cannulating a hind limb lymphatic, lymph was infused directly into the LAD before and after a 10-second 100 degrees C hind limb scald. Scalding alone did not alter myocardial contractile performance in the LAD or LCx regions, coronary artery blood flow, or systemic hemodynamics. Interestingly, postburn lymph infused into the LAD resulted in a 38% decline in LAD zone segment shortening (p < 0.01 vs baseline) that lasted throughout the 5-hour observation period. In contrast, segment shortening in the (control) LCx region was unaffected by postburn lymph injections into the LAD. Regional myocardial blood flow (radiolabeled microspheres) in the LAD and LCx regions was unchanged after scald injury or intracoronary injection of postburn lymph. In addition, LAD coronary artery vascular reactivity to acetylcholine and nitroglycerin was also unaffected by the regional thermal injury or by injection of lymph into the LAD. These data suggest that a regional scald injury results in the production and release of a potent myocardial depressant factor(s) that produces a direct negative inotropic effect on the canine myocardium.

Indomethacin-induced reduction in neonatal piglet mesenteric blood flow is blunted by dopexamine

BACKGROUND

Dopexamine is a specific dopaminergic and beta2-adrenergic agonist. Using newborn piglets, we have previously shown that (1) dopexamine increases cardiac output and mesenteric blood flow; (2) indomethacin reduces mesenteric blood flow.

METHODS

Ultrasonic blood flow probes were placed around the ascending aorta, cranial mesenteric artery, and a renal artery of 0 to 2-day-old and 2-week-old piglets. Animals of each age were grouped (5 to 8 animals per group) and subjected to one of three experimental protocols: (1) 0.4 mg/kg indomethacin infusion, (2) 10 microg/kg/min dopexamine infusion begun 10 minutes before indomethacin, or (3) no treatment.

RESULTS

Control animals demonstrated no significant alterations in mesenteric blood flow. Compared with baseline, indomethacin produced significant (P< .05, analysis of variance) declines in cranial mesenteric artery blood flow in 0 to 2-day old (37.2+/-5.7 mL/min v 17.9+/-3.7 mL/min at 90 min), and 2-week-old (80.2+/-12.5 mL/min v 29.7+/-5.7 mL/min at 90 minutes) piglets. In both animal groups treated with dopexamine before indomethacin, the decreases in cranial mesenteric artery blood flow were eliminated (38.4+/-7.6 mL/min at baseline v 36.5+/-6.8 mL/min at 90 minutes in 0 to 2 day olds; 79.9+/-10.0 mL/min at baseline v 77.5+/-14.7 mL/min in 2 week olds). Indomethacin-induced declines in renal blood flow were similarly abrogated by dopexamine.

CONCLUSION

Dopexamine may prove of clinical benefit when a neonate is considered a candidate for indomethacin therapy.

Development of a novel synthetic material to close abdominal wall defects

To compare the efficacy of a novel synthetic material (TMS-2) with polytetrafluoroethylene, polypropylene (Marlex), and primary closure of experimentally fashioned clean and contaminated abdominal wounds, 1-cm2 abdominal wall defects were created in each of the four abdominal quadrants of rats (n = 10). Patches of each material were used to repair three of these defects, the fourth being primarily closed. A second group of rats (n = 7) underwent the same operative protocol; however, peritonitis was induced at the time of surgery using a fecal inoculation technique. Animals were killed 2 weeks later, and surface area and severity of formed adhesions were assessed by a "blinded" observer. All closure techniques were successful insofar as none demonstrated fascial dehiscence. Compared with each synthetic material, the surface area of formed adhesions was smaller after primary closure in clean and in contaminated conditions; however, the three synthetic materials were equally matched regarding surface area of adhesions under both conditions. In the face of fecal contamination, TMS-2 proved identical to primary closure, each generating significantly (P < 0.02) milder adhesions than the other prosthetic materials. It is concluded that the TMS-2 may prove of clinical benefit to repair abdominal wall defects.

Comparison of novel synthetic materials with traditional methods to repair exposed abdominal wall fascial defects

Repair of large abdominal wall defects is a challenge, particularly when full-thickness tissue loss prohibits coverage of the fascial repair. Two novel synthetic materials (TMS-1 and TMS-2) have been shown to be better accepted than expanded polytetrafluoroethylene (Gore-Tex), and polypropylene (Marlex) in the closure of clean and contaminated fascial wounds that are immediately covered by skin/soft tissue. Therefore, 1-cm2 abdominal wall defects were created in each of the four quadrants of rat groups. Gore-Tex, Marlex, and TMS-1 or TMS-2 were used to repair three defects, the fourth being primarily closed. To ensure that each repair remained exposed, skin edges were sutured to underlying muscle. Additional animal groups underwent the same protocol; however, peritonitis was induced at surgery using a fecal inoculum technique. Animals were sacrificed 2 weeks later, at which time a blinded observer assessed the surface area and severity of adhesions. In clean wounds, the surface area of formed adhesions was less (p < .004) after primary closure than each synthetic material; among the synthetics, TMS-2 caused significantly (p < .01) less extensive adhesions than Marlex. In addition, the severity of adhesions to TMS-2 was comparable to that of defects closed primarily, and less severe (p < .02) than those formed to Gore-Tex and Marlex. In animals with peritonitis, primary closure caused less extensive (p < .03) adhesions than Marlex and Gore-Tex and significantly (p < .002) less severe adhesions than Marlex, Gore-Tex, and TMS-2. However, the severity of adhesions formed to TMS-1 repairs proved comparable to primarily closed wounds. These experiments reaffirm the tenet that, whenever possible, abdominal wounds should undergo primary fascial closure. When soft tissue coverage over the repair cannot be achieved, TMS-2 is well tolerated in clean wounds. However, the superiority of TMS-1 over the other synthetic materials in contaminated wounds suggests it may also ultimately prove to be of clinical utility.

Age-related differences in response to neutrophil-mediated reperfusion injury in the neonatal piglet heart

BACKGROUND

Neonatal hearts have altered adhesion molecule interactions in response to ischemia-reperfusion. How this affects myocardial function is unknown.

METHODS

Isolated, buffer perfused 0- to 2-day (newborn) and 2-week piglet hearts were first subjected to 20-minute global, normothermic ischemia, followed by 45 minutes of reperfusion during which 150 x 10(6) newborn or 2-week neutrophils were infused. In some hearts, an antibody to SLe(x) (CSLEX-1) was infused with neutrophils during reperfusion. Hemodynamic variables, including left ventricular developed pressure (LVDP), were recorded at timed intervals. Neutrophil CD-18, L-selectin, and SLe(x) contents were measured by flow cytometry.

RESULTS

Full recovery of LVDP was observed in newborn hearts receiving newborn or 2-week-old neutrophils. Recovery of LVDP was depressed (p < 0.01, ANOVA) in 2-week-old hearts receiving 2-week old, not newborn, neutrophils. Infusion of CSLEX-1 in 2-week-old hearts restored LVDP to baseline. Whereas flow cytometry showed higher (p < 0.01, Student's t test) CD-18 and L-selectin expression on newborn versus 2-week-old neutrophils, newborn neutrophils expressed lower (p < 0.01) SLe(x) levels.

CONCLUSIONS

Initial "loose" neutrophil-endothelial selectin interactions are a necessary prelude to "firm" adhesion and reperfusion injury. Operations performed soon after birth may be better tolerated than when surgery is delayed; anti-SLe(x) preparations may prove beneficial when performing cardiac procedures on older infants.

The incidence of secondary hernias diagnosed during laparoscopic total extraperitoneal inguinal herniorrhaphy

During a 24-month period beginning in July of 1995, laparoscopic total extraperitoneal inguinal herniorrhaphy was attempted in 53 patients. All procedures were performed at a single institution, by senior-level general surgery residents, with the same attending surgeon functioning as first assistant. Three patients required conversion to an "open" procedure (all had a prior history of herniorrhaphy or lower abdominal surgery), leaving 50 patients for analysis. Preoperatively, a unilateral hernia was evident on clinical grounds in 29 patients, the remaining 21 presenting with signs of a bilateral hernia; of the total, 11 had a history of prior hernia repair on the presently affected side. At surgery, a total of 115 hernia defects (indirect, direct, femoral) were identified, 38% of which were discovered only at the time of surgery. Sixty-four percent of patients were found to have at least one of these "secondary" hernias. After reduction of the hernia(s), all defects were covered with polypropylene mesh secured with spiral tacks. There were 10 perioperative complications, one of which required corrective surgical intervention. Over 70% of patients were discharged on the day of surgery; 92% returned home within 23 h of their operation. The most common reason for delay of hospital discharge was urinary retention. There have been no recurrences in short-term follow-up. Most patients were pleased with the recovery time from and the cosmetic results of their surgery. These results suggest that laparoscopic total extraperitoneal herniorrhaphy represents a safe, effective, cosmetically appealing alternative to open hernia repair. Moreover, this approach may provide an added advantage insofar as identifying additional hernia defects that, when repaired, may ultimately yield a lower recurrence rate than might otherwise have been expected.

What's black and white and red (read) all over? The bedside interpretation of diagnostic peritoneal lavage fluid

Diagnostic peritoneal lavage (DPL) is often used to determine whether a blunt trauma victim has significant intra-abdominal hemorrhage. One bedside test (BT) historically recommended to evaluate DPL fluid is the ability to read newsprint through the fluid contained within intravenous (i.v.) tubing. Few experimental data support this practice. Two hundred eighteen traumatologists were queried regarding their use of BTs. In a related clinical study, blinded volunteers were asked to read print through various unmarked containers filled with simulated DPL fluid, created by adding aliquots of whole human blood to liter bags of lactated Ringer's solution. Of the 97 traumatologists who completed our preliminary survey, 60 per cent reported using a visual BT to assess DPL fluid. Of these surgeons, 44 per cent attempted to read newsprint through i.v. tubing. Our clinical study showed that more volunteers could read print through a red top tube (95%) when it contained a red cell concentration of 827 +/- 41/mm3 than the i.v. bag (4%). Nearly 70 per cent of volunteers were able to read print through the tubing containing 41,429 +/- 2,967 red blood cells (RBCs)/mm3. Regardless of the receptacle, readability was lost at RBC counts far below 100,000/mm3. Many traumatologists utilize BTs as an adjunct to clinical decision making. We conclude that, if the clinician can read print through lavage fluid within an i.v. bag, Vacutainer tube, or i.v. tubing, the DPL will be negative at cell count. However, inability to read print through i.v. tubing requires laboratory confirmation to document an RBC count > 100,000/mm3.

Alpha-trinositol reduces edema formation at the site of scald injury

BACKGROUND

The effects of alpha-trinositol (1D-myo-inositol-1,2,6-triphosphate, IP3) on burn-induced edema formation were investigated.

METHODS

Lymph flow (QL; microliter/min) and lymph-to-plasma protein ratio (CL/CP) were monitored in groups of five to six dogs before and 4 hours after (1) a 5-second 100 degrees C or 90 degrees C foot paw scald; (2) IP3 (45 mg/kg intravenous bolus, then a 20 mg/kg/hr infusion) 30 minutes before or after 100 degrees C scald, or 30 minutes after 90 degrees C scald. Hind paw venous pressure was elevated and maintained by outflow restriction until reaching steady state QL and (CL/CP)min. Macromolecular reflection coefficient (1-CL/CP) was measured. Fluid filtration coefficient (Kf; ml/min/mm Hg/100 gm) was calculated. Relative paw weight gain (%) was measured.

RESULTS

Compared with preburn values, scald uniformly produced significant increases in QL, CL/CP, and Kf, IP3 significantly (p < 0.02, ANOVA) reduced paw weight gain when given before, but not after, 100 degrees C burn (41% +/- 5% versus 18% +/- 7% preburn IP3 and 31% +/- 3% postburn IP3). Compared with 90 degrees C burn animals, postburn treatment significantly (p < 0.017) attenuated 4-hour increases in QL (550 +/- 87 versus 252 +/- 29 microliters/min), Kf (0.016 +/- 00 versus 0.007 +/- 00 microliter/min/mm/Hg/100 gm), and relative paw weight gain (28% +/- 3% versus 12% +/- 5%).

CONCLUSIONS

alpha-Trinositol given after a 90 degrees C scald blunted edema formation at the site of scald, likely through reduced transmembrane fluid flux.

Mild preischemia hypothermia adversely affects postischemic myocardial function in the neonatal piglet heart

BACKGROUND

During cardiac surgery, operative hypothermia has been shown to be beneficial in certain situations, although in children perioperative hypothermia has been associated with several physiologic alterations that have proven detrimental to their postoperative function. Little attention has been given to the effects of mild (34.5 degrees C) perioperative hypothermia on postischemic myocardial function in the pediatric population. It was hypothesized that mild hypothermia would be detrimental to postischemic ventricular function in the neonatal heart.

METHODS

Neonatal (0-2 days old) piglets were subjected to mild perioperative hypothermia without rewarming (HT-only, n = 6), hypothermia followed by rewarming (HT-RW, n = 6), or continuous normothermia (NT, n = 8). The hearts were rapidly excised, suspended on an isolated perfusion apparatus, and allowed to spontaneously beat while being perfused with an asanguinous solution. All hearts were subjected to 20 min global, normothermic, zero-flow ischemia followed by 45 min oxygenated crystallite buffer reperfusion (I-R).

RESULTS

Compared to that of NT piglets, there were significant (P < 0.05) reductions in recovery of left ventricular (LV) diastolic and systolic function following ischemia and reperfusion in HT-RW animals. When the hearts were rendered ischemic without first rewarming, the degree of myocardial dysfunction was not as severe. In contrast to the NT piglets, HT-RW animals demonstrated significant (P < 0.05) reductions in the final recovery of LV developed pressure (71 +/- 6 vs 105 +/- 6 in NT), LV rate pressure product (52 +/- 4 vs 102 +/- 9 NT), and LV end diastolic pressure (32 +/- 7 vs 3 +/- 1 in NT) following I-R. When compared to the HT-RW group, HT-only piglets did not exhibit significant differences in systolic function, although diastolic function was minimally altered initially as evidenced by the slight elevation of LV end diastolic pressure at 5 min, with reperfusion in the HT-only group (P < 0.05).

CONCLUSIONS

In this newborn piglet model, mild hypothermia significantly reduces recovery of systolic and diastolic left ventricular function when followed by an episode of global myocardial ischemia-reperfusion only when the animals are returned to normothermia prior to the ischemic insult. When hypothermia is immediately followed by the ischemic event, left ventricular function is unaffected.

A novel model to study the effects of burn lymph on pulmonary vascular hemodynamic variables

OBJECTIVE

To determine the effects of burn lymph on pulmonary hemodynamic variables.

METHODS

A balloon-tipped catheter was fluoroscopically passed from a jugular vein into the right lower lobe (RLL) pulmonary artery of rats, its distal lumen used to measure pulmonary artery pressure. Inflation allowed measurement of RLL wedge pressure, which represents pulmonary venous pressure. After inflation, the RLL underwent constant flow pump-perfusion with carotid artery blood. Preburn (n = 5) or post-burn (n = 6) dog lymph was infused into the RLL for 50 minutes.

MEASUREMENTS

Because perfusion flow rate was constant throughout the experiment, RLL changes in pulmonary artery pressure reflect changes in pulmonary vascular resistance.

RESULTS

Animals given preburn lymph had no alterations in RLL pulmonary hemodynamics. The immediate, significant (p < 0.005, analysis of variance) increases in RLL pulmonary artery pressure (16.2 +/- 2.3 mm Hg at baseline vs. 35.4 +/- 2.1 mm Hg at 30 minutes) and pulmonary vascular resistance (0.0 at baseline vs 1.37 +/- 0.24 at 30 minutes) after burn lymph injection persisted beyond infusion interruption.

CONCLUSION

The persistent pulmonary hypertensive response to postburn lymph warrants further investigation.

Dopexamine maintains mesenteric blood flow during systemic hypoxemia in the neonatal piglet

In adults, dopexamine is a specific dopaminergic and Beta2-adrenergic agonist; its effects in neonates are unknown. Ultrasonic flow probes were placed around the ascending and descending aorta and cranial mesenteric artery of 0- to 2-day-old and 2-week-old piglets. Animals of each age group (9 to 14 per group) were subjected to (1) dopexamine infusion (5 microg/kg/min); (2) 30 minutes of hypoxia (inspired oxygen content 0.12) followed by 30 minutes of reoxygenation; and (3) dopexamine infusion during hypoxia and reoxygenation. In both age groups dopexamine alone increased ascending aorta blood flow (cardiac output minus coronary artery blood flow), mildly decreased mean arterial pressure, and increased cranial mesenteric artery blood flow. Compared to baseline values, 30 minutes of hypoxia produced significant (P <0.05, analysis of variance) decreases in cranial mesenteric artery blood flow in 0- to 2-day-old (58 +/- 13 ml/min vs. 30 +/- 8 ml/min) and 2-week-old (125 +/- 18 ml/min vs. 60 +/- 11 ml/min) piglets. In all cases blood flow returned to baseline values after reoxygenation. In both animal groups treated with dopexamine before hypoxia, the decreases in cranial mesenteric artery blood flow were eliminated (47 +/- 5 ml/min vs. 44 +/- 6 ml/min in 0- to 2-day-old piglets; 140 +/- 27 ml/min vs. 117 +/- 18 ml/min in 2-week-old piglets). Dopexamine may prove to be of clinical benefit when neonates are threatened by hypoxemia-induced decreases in intestinal blood flow.

Adrenomedullin mediates coronary vasodilation through adenosine receptors and KATP channels

The following experiments were conducted to determine whether, and the mechanisms through which, endogenous peptides alter coronary artery blood flow. Ultrasonic transit time probes were placed around the ascending aorta and left anterior descending coronary artery in groups of anesthetized, open-chest dogs. A Millar pressure catheter monitored left ventricular developed pressure. Intracoronary artery bolus injections of adenosine (a purinergic receptor activator), pinacidil (a KATP channel activator), calcitonin gene-related peptide (CGRP; which causes vascular smooth muscle relaxation by intracellular increases in cyclic-AMP), and adrenomedullin (mechanism unknown) each significantly (P < 0.05, Student's t test) increased coronary blood flow in a dose-dependent fashion, without altering systemic hemodynamic measurements. Intracoronary artery injection of U37883A (a KATP channel antagonist) significantly (P < 0.05) blocked the coronary vasodilator responses to adenosine, adrenomedullin, and pinacidil. Intracoronary xanthine amine congener (an adenosine receptor antagonist) blocked only the responses to adenosine and adrenomedullin, not pinacidil. Intracoronary CGRP8-37 (CGRP receptor antagonist) blocked only the vasodilator response to CGRP. These data suggest that the coronary vasodilator effect of adrenomedullin is initiated first by activation of adenosine receptors, and subsequently through KATP channels-not by activation of CGRP receptors. That there were no changes in left ventricular developed pressure or in systemic hemodynamics after intracoronary artery infusions of adrenomedullin indicates that this endogenous peptide may have clinical utility in facilitating myocardial protection or preconditioning.

Characterization of alpha-adrenoceptor activity in the preterm piglet mesentery

To characterize neonatal mesenteric alpha-adrenoceptor populations, an extracorporeal perfusion circuit was established to control intestinal blood flow in prematurely delivered (by cesarean section at 90% of gestational age) piglets. Activation of alpha 1-adrenoceptors was documented by observing dose-dependent increases in mesenteric perfusion pressure after intramesenteric arterial injection of methoxamine; alpha 2-adrenoceptor activity was confirmed by finding similar increases in mesenteric perfusion pressure after intramesenteric arterial injections of BHT 933. Peripheral intravenous injections of WB 4101 (a competitive alpha 1A-adrenoceptor antagonist), but not clorethylclonidine (CEC, an alpha 1B-adrenoceptor antagonist), significantly blunted (P < .05, ANOVA) the mesenteric vasoconstrictor responses to methoxamine. The mesenteric vasoconstrictor response to BHT 933 (an alpha 2-adrenoceptor agonist) also was blunted by WB 4101, but not by CEC. These data suggest that alpha 1A- and alpha 2-adrenoceptors can be activated in the small intestinal mesentery of piglets well before they reach full-term maturation, although receptor specificity has not been fully established.

Characterization of alpha-adrenoceptor activity in term-newborn piglet mesentery

For further characterization of neonatal mesenteric alpha 1-adrenoceptor populations, an extracorporeal perfusion circuit was established to control intestinal blood flow in 0-2 day old piglets. Activation of alpha 1-adrenoceptors was first documented by observing dose-dependent increases in mesenteric perfusion pressure after intra-mesenteric arterial injection of methoxamine and noradrenaline. Peripheral intravenous injections of WB 4101 (a competitive alpha 1A-adrenoceptor antagonist), but not clorethylclonidine (CEC, an alpha 1B-adrenoceptor antagonist), significantly (P < 0.05, analysis of variance) blunted mesenteric vasoconstrictor responses to those agonists. That the mesenteric vasoconstrictor response to mesenteric plexus stimulation was unaltered by CEC, but was muted by both WB 4101 and SK&F 104856 (a post-junctional alpha 1- and alpha 2-adrenoceptor antagonist) suggests that pre- and post-junctional alpha 1A-adrenoceptors are present and functional at birth.

Small bowel necrosis in association with jejunostomy tube feedings

Nutritional support is thought to be an important adjunct for minimizing perioperative morbidity. For a variety of reasons, it is now felt that nutrition delivered by the enteral route is preferred over that given parenterally. Although delivery of nutrients into the small intestine, either via a nasoduodenal tube or a surgically placed jejunostomy, is effectively tolerated by most patients, morbid complications are being described with increased frequency. Herein, we describe two patients who underwent major intra-abdominal surgery, one for a malignancy, the other for trauma management. Immediate postoperative feedings were instituted through a surgically placed jejunostomy tube. Several days later, each patient underwent emergency reoperation for clinical findings of an intra-abdominal catastrophe. In both patients, small intestinal infarction in juxtaposition to the site of the tube feedings was found. This experience suggests that the enteral feedings were causally related to this morbid complication, which proved fatal in one patient.

Iatrogenic esophageal pseudodiverticulum: a case report

Iatrogenic injury of the esophagus is not an uncommon complication of diagnostic endoscopy and dilation. Herein is described what is felt to be the first reported case of a traumatic pseudodiverticulum after dilation of an esophageal stricture. The management of what was preoperatively felt to be an esophageal perforation is discussed.

Effects of anti-inflammatory agents on hydrochloric acid-induced pulmonary injury

To determine the effects of anti-inflammatory agents on hydrochloric acid lung injury, the heart and lungs were harvested from rats, placed in a lung chamber, constant flow perfused with whole blood, and ventilated. The following experiments were conducted: observation alone; intratracheal injection of normal saline; intratracheal hydrochloric acid; and intravenous meclofenamate or indomethacin before intratracheal hydrochloric acid. Wet-to-dry lung weights were measured. Peak airway pressures increased immediately (p < .001 vs. baseline; ANOVA) in all intratracheal groups, hydrochloric acid producing even greater (p < .05) increases than saline-effects unaltered by meclofenamate or indomethacin. The increased (p < .001 vs. baseline) 2-h pulmonary artery pressures in hydrochloric acid-treated groups were unaltered by meclofenamate or indomethacin. All hydrochloric acid-treated groups demonstrated increases (p < .05) in weight that were unchanged by meclofenamate or indomethacin. These data suggest that the beneficial effects of these medications described elsewhere, using a variety of in vivo lung injury experimental models, may be attributed to their experimental design, or to contributions from organs/systems outside the pulmonary circuit.

Effect of maturation on alpha-adrenoceptor activity in newborn piglet mesentery

To characterize the mesenteric alpha1- and alpha2-adrenoceptor populations in newborn piglets, an extracorporeal circuit was established to control intestinal blood flow in 0- to 2-day old and 10- to 14-day old animals. In both groups, alpha-adrenoceptor activation was first documented by observing dose-dependent increases in mesenteric perfusion pressure after intramesenteric arterial injection of alpha-adrenoceptor agonists. In the 10- to 14-day old piglets, mesenteric vasoconstrictor responses to alpha1-adrenoceptor agonists (methoxamine and norepinephrine) and an alpha2-adrenoceptor agonist (BHT-933) were each blunted (P < 0.05, analysis of variance) by peripheral intravenous injections of prazosin (an alpha1-adrenoceptor antagonist) and yohimbine (an alpha2-adrenoceptor antagonist), respectively. The mesenteric vasoconstrictor responses to those agonists were not significantly attenuated by prazosin or yohimbine in 0- to 2-day old animals, nor were they blunted by YM-12617 (alpha1-adrenoceptor antagonist) or idazoxan (alpha2-adrenoceptor antagonist)--compounds that are structurally unrelated to prazosin and yohimbine, respectively. In addition, mesenteric vasoconstrictor responses to other known vasoconstrictor agents--angiotensin II, neuropeptide Y, and a thromboxane A2 mimic (U-46619)--were not effected in either age group by prazosin or yohimbine, implying these agents act independently of alpha-adrenoceptor mechanisms. These data suggest that (1) there exists functional mesenteric alpha1- and alpha2-adrenoceptor-like activity in 10- to 14-day old piglets that, in 0- to 2-day old animals, is not specifically expressed; and (2) mesenteric alpha-adrenoceptor function becomes more selective as newborn piglets mature.

Burn edema reduction by methysergide is not due to control of regional vasodilation

To determine the extent to which edema modulation by methysergide is due to a blunting of the regional vasodilator response to scald and/or local reduction of transvascular fluid flux, a canine hind limb lymphatic was cannulated. Femoral blood flow (Qa; ml/min), lymph flow (QL; microliter/min/100 g), and lymph-to-plasma protein ratios (CL/CP) were monitored in groups of five dogs before and 4 hr after 5-sec, 100 degrees C foot paw scald; high (1.0 mg/kg) or low (.5 mg/kg) dose of methysergide 30 min before scald. The compression on a clamp placed around the femoral artery in other dogs was adjusted after scald to simulate the blunting effect on Qa observed in methysergide treated dogs. Hind leg venous pressure was elevated to approximately = 40 mm Hg before experimentation until steady state QL and (CL/CP)min were reached. Protein reflection coefficient (sigma d; 1-C1/ CP) and fluid filtration coefficient (Kf) were calculated. Compared to preburn values, all groups showed significant (P < 0.002, analysis of variance) increases in CL/CP and Kf. Contrasted with the burn only group, methysergide blunted increases in Qa, Kf and paw weight gain in a dose-dependent fashion, with no effect on the reflection coefficient. Compression clamp control of femoral Qa caused no effects on permeability. Methysergide limits burn edema in a dose-related fashion, though not due to a blunting of the regional vasodilator response. Local, not regional, mechanism(s) likely mediate this response.

Evaluation of a novel synthetic material for closure of large abdominal wall defects

BACKGROUND

This study was undertaken to compare the efficacy of a novel synthetic material (TMS-1) with polytetrafluoroethylene, polypropylene, and primary closure of experimentally fashioned clean and contaminated abdominal wounds.

METHODS

One square centimeter full-thickness abdominal wall defects were created in each of the four abdominal quadrants of anesthetized rats (n = 6). Patches of polytetrafluoroethylene, polypropylene, and a polyurethane-polypropylene composite material (TMS-1) were used to repair three of these defects; the fourth was primarily closed. A second group of rats (n = 9) underwent the same operative protocol; however, peritonitis was induced at the time of operation by using the fecal inoculation technique. Animals were killed 2 to 3 weeks later, and surface area and severity of formed adhesions were assessed.

RESULTS

By all methods of assessment, primary closure proved significantly superior to all other methods of closure in clean and contaminated conditions. The three synthetic materials were equally matched for surface area involved in adhesion formation. When compared with the other synthetic materials, TMS-1 was associated with significantly milder adhesions in uninfected (p < 0.002) and in infected (p < 0.002) conditions.

CONCLUSIONS

The clear superiority of TMS-1 over other nonabsorbable synthetic materials shown in this pilot study warrants further investigation relative to its use to close large abdominal wall defects.

Polypropylene mesh closure of the complicated abdominal wound

BACKGROUND

Closure of the abdominal wall in the face of fascial necrosis or massive intestinal edema remains a difficult problem with frequent complications. Prior studies have addressed both the utility and the pitfalls of placing polypropylene mesh in this setting.

METHODS

We performed a retrospective evaluation of our experience with polypropylene mesh in traumatic and nontraumatic difficult abdominal closures. Timing of mesh placement and removal relative to the initial operation were recorded, as were abdominal complications, number of operative procedures, and type of ultimate abdominal closure.

RESULTS

Between 1988 and 1993, polypropylene mesh was placed in 26 critically ill or injured patients requiring celiotomy, of whom 23 survived more than 3 weeks. Ultimate wound management was delayed mesh removal and primary closure (17%), myocutaneous flap coverage over mesh (4%), split-thickness skin grafting to the granulating wound (35%), or closure by secondary intention over mesh (43%). Split-thickness skin grafting and closure by secondary intention resulted in enterocutaneous fistulas in 50% and 40% of cases, respectively. Full-thickness closure with or without mesh removal resulted in no fistulas.

CONCLUSION

Mesh provided adequate fascial closure, even with gross wound contamination. Coverage of polypropylene mesh by secondary intention or split-thickness skin grafting resulted in unacceptably high rates of fistulous complications, and this procedure should be replaced by either mesh removal or full-thickness coverage.

Serotonin receptors regulate canine regional vasodilator responses to burn

OBJECTIVE

To determine which serotoninergic receptor subtype(s) mediates the regional vasodilator response to scald injury.

DESIGN

Prospective, randomized trial.

SETTING

Microcirculation research laboratory.

SUBJECTS

Anesthetized dogs.

INTERVENTIONS

Mechanically ventilated dogs underwent cannulation of a brachial artery and placement of an ultrasonic flow probe around one femoral artery. All animals received a 2% to 3% body surface area partial thickness scald injury by immersing the paw ipsilateral to the instrumented femoral artery into 100 degrees C water for 5 secs. In one group of dogs, BMY 7378 (a serotoninergic1A receptor antagonist) was given by the peripheral intravenous route before burn. These results were compared with those findings obtained from a group of animals that received a burn only, and groups of animals given a peripheral intravenous injection of methysergide (a serotoninergic receptor antagonist) or ritanserin (a serotoninergic2 receptor blocking agent) before burn. Experiments were conducted for two postburn hours.

MEASUREMENTS AND MAIN RESULTS

Burn injury caused a marked and persistent increase in regional (e.g., femoral artery) blood flow, an effect that was significantly blunted by preburn administration of the serotoninergic receptor antagonist, methysergide. Preburn administration of BMY 7378 increased baseline femoral blood flow by 13%, reflecting its known serotonin agonist properties. However, when compared with the mean postscald increases in femoral blood flow over baseline seen in scald only dogs and in animals given the serotoninergic2 receptor blocking agent, ritanserin (before scald), the BMY 7378-treated group demonstrated a significant (p < .001 by analysis of variance) 2-hr-postscald blunting of this femoral vasodilator response.

CONCLUSION

These data suggest that serotoninergic1A-like receptors play an integral, albeit not an exclusive, role in blood flow regulation to the site of burn injury.

Prospective assessment of the value of computed tomography for trauma

The use of computed tomography (CT) has helped revolutionize the process and accuracy of diagnosis of the trauma patient. We have noted a striking increase in the use of CT scanning early in the management of trauma patients at our trauma center and sought to assess our experience.

METHODS

All trauma patients admitted to our trauma center from February 1991 to February 1992 who received any CT scan within the first 12 hours after arrival were enrolled in the study. A positive (+) CT scan was defined as a scan that demonstrated a significant finding consistent with the injury and a negative (-) CT scan was one in which there were either no abnormalities or only incidental findings unrelated to the injury. Each patient was followed daily by one of the authors (A.G.R.). Patient records were reviewed and treating surgeons were interviewed to determine whether the CT scan improved the process of therapy. Morbidity incident to the performance of the CT scans was assessed.

RESULTS

1609 trauma patients underwent 2047 CT scans (1.3 CT scans per patient). Sixteen percent (n = 260) had scans of more than one part of the body. Thirty-eight percent (n = 770) of scans were positive but 29% (n = 225) of these were not helpful to the patient care process. Overall, 29% of scans, either because they were positive or negative, assisted in the clinical care of the patient. Six percent (n = 45) of CT scans were falsely positive. Sixty-five percent of scans were true negatives. Two patients died in the CT suite, 6 died shortly after completion of the scan, and 12 required emergency trips to the operating room from the CT suite.

CONCLUSIONS

A large number of CT scans are being performed in our trauma patient population. Less than 30% contributed to patient management. Because of morbidity and cost, strict surgeon and radiologist oversight of CT for trauma is essential.

Effects of methysergide administration on edema formation at the site of scald

Femoral blood flow (Qa), hind paw lymph flow (Qlym), and lymph-to-plasma protein concentration ratio (Clym/Cp) were monitored before and 4 h after 1) 5-s 100 degrees C paw scald, 2) methysergide (1 mg/kg iv) 20 min before scald, 3) methysergide 30 min after scald, and 4) methysergide only. Before experimentation, hind paw venous pressure was elevated and maintained until steady-state Qa, Qlym, and minimal Clym/Cp levels were reached. The reflection coefficient (sigma d) was determined as 1 - minimal Clym/Cp; the filtration coefficient (Kf) was calculated. Methysergide alone caused no changes. Increases in Qa, Qlym, Clym/Cp, and Kf were identified in all scald groups. Compared with scald only animals, pre- and postscald methysergide blunted the increases in Qa, Qlym, Kf, and paw weight gain without an effect on sigma d. These data demonstrate that methysergide reduces edema formation at the site of scald, perhaps by modulating the burn-induced vasodilator response and/or by limiting the burn-induced increase in microvascular surface area.

Laparoscopic cholecystectomy: what's so special?

One hundred seventy-one laparoscopic cholecystectomies were done by senior surgery residents who received only traditional "hands-on" training. Eight patients (5%) required conversion to open cholecystectomy, and two had complications requiring immediate celiotomy (one common bile duct injury, one "dropped" gallbladder). The average operative time was 91 minutes (range, 30 to 245 minutes). There were no deaths and only five postoperative complications related to the procedure (retained common bile duct stone in four cases, intra-abdominal hemorrhage in one). There were three complications unrelated to the procedure. Data acquired from recent resident training program graduates show that these practicing surgeons are doing laparoscopic cholecystectomy with a 95% success rate and have yet to encounter appreciable complications. We concluded that a large-volume general surgery resident training program provides adequate opportunity for training surgeons in the techniques of laparoscopic cholecystectomy; there is no need to attend an expensive and time-consuming classroom and animal laboratory course.

Preventive antibiotic usage in traumatic thoracic injuries requiring closed tube thoracostomy

OBJECTIVE

To evaluate the safety and effectiveness of antibiotics in reducing the infectious complications following closed tube thoracostomy for isolated chest trauma.

DESIGN

Double-blind, randomized clinical trial.

SETTING

Medical school affiliated large urban teaching hospital and trauma center.

PATIENTS

One hundred nineteen of 159 patients over 18 years old presenting to the emergency department requiring closed tube thoracostomy for isolated chest injuries (113 penetrating, 6 blunt).

INTERVENTION

Patients received either placebo or 1 g cefonicid daily intravenously started at chest tube insertion and stopped within 24 h of removal.

MEASUREMENTS AND RESULTS

The development of wound infections, pneumonia (CDC criteria), or empyema; the incidence of adverse events; length of hospitalization. One nonspecific infection was seen in the cefonicid group (1.6 percent) and six respiratory tract infections (10.7 percent) in the placebo group (three empyema, one empyema with pneumonia, two pneumonia) (p = 0.0505; p = 0.0094 [excluding nonspecific infection]). No significant differences with antibiotic use were seen in the duration of chest tube use (p = 0.766), peak WBC counts (p = 0.108), lower peak temperatures (p = 0.063), or length of hospitalization (p = 0.165). Patients who developed infectious complications averaged approximately 8 days longer hospitalization than those without (p < 0.0001).

CONCLUSION

This study showed that patients receiving antibiotics had a significantly reduced rate of infection than did patients administered placebo. No significant adverse events were seen in either group.

Effects of graded thermal injury on microvascular permeability at the site of injury

To define whether capillary permeability traits at the site of a burn differ according to injury severity, a canine hind leg lymphatic was cannulated to measure macromolecular permeability in response to three different scalding solutions. Leg venous pressure was raised to approximately 40 mm Hg and maintained until a minimal lymph-to-plasma total protein ratio (CL/CP)min and steady-state lymph flow (QL; microliter/min/100 g) was attained. The protein reflection coefficient (1-CL/CP), fluid filtration coefficient (Kf; microliter/min/mm Hg/100 g), and QL were determined before and for 6 hr after a 5-sec hind paw immersion in either 100 degrees C (n = 7), 80 degrees C (n = 7), or 70 degrees C (n = 7) water. A group of five animals served as controls. In the absence of any systemic hemodynamic alterations, the 100 and 80 degrees C scald groups experienced significant (P < 0.05, ANOVA) increases in QL, CL/CP, and Kf as compared to respective preburn values and time-matched unburned control values. Most monitored parameters were significantly higher following 100 degrees C injury vs 80 degrees C injury. Parameters in the 70 degrees C group did change after scald, but were not significantly different from preburn values or from the control group. Alterations in capillary permeability to protein and fluid flux measured at the burn site are graded, not all or none phenomena, being dependent upon the severity of injury.

Utility of the biofragmentable anastomotic ring in traumatic small bowel injury

OBJECTIVE

To evaluate the use of the 25 mm Biofragmentable Anastomotic Ring (BAR) in traumatic small bowel injury.

METHODS

In a one year prospective, nonrandomized study, 18 patients (x age = 25 yrs) with penetrating small bowel injury had 25 BAR devices placed to restore intestinal continuity. Using one-way analysis of variance, this group was compared to 63 historical controls (x age = 27 yrs) with small bowel trauma who had either sutured or stapled anastomoses (SSA), with regard to Penetrating Abdominal Trauma Index (PATI) score, time until return of bowel function, and postoperative morbidity.

RESULTS

PATI scores for the two groups were not significantly different (P = 0.099). No deaths in the SSA group (n = 8) or in the BAR group (n = 1) were related to the anastomotic technique. There was no significant difference (P = 0.991) in the rate of post-operative intestinal obstruction between BAR (n = 3) and SSA (n = 8) groups; none of the BAR patients required re-operation. The average length of time for return of bowel function was not significantly different (P = 0.197) between BAR (4.3 days) and SSA (5.8 days) groups.

CONCLUSIONS

The 25 mm BAR may be used in the repair of traumatic small bowel injury, based upon comparable outcomes when compared with sutured and stapled anastomoses.

Effects of pentafraction administration on microvascular permeability alterations induced by graded thermal injury

BACKGROUND

Pentafraction is a pentastarch derivative hypothesized to limit burn edema by "sealing" damaged capillaries, restoring a barrier to fluid translocation and macromolecular (protein) flux.

METHODS

Canine hind paw lymph flow (QL) and lymph (CL) and plasma (CP) protein concentrations were measured before and for 6 hours after (1) 5-second 100 degrees C (n = 6) or 80 degrees C (n = 6) foot paw scald, (2) 100 degrees C (n = 5) or 80 degrees C (n = 5) foot paw scald followed 30 minutes later by a 4 cc/kg bolus of 6% pentafraction, or (3) pentafraction infusion without scald (n = 5). Before scald or pentafraction infusion, hind paw venous pressure was elevated and maintained by outflow restriction until a steady state, minimal CL/CP was reached. The reflection coefficient, sigma d, was determined as 1-CL/CP, and the (fluid) filtration coefficient (Kf) was calculated.

RESULTS

Scalding uniformly produced statistical (p < 0.05, ANOVA) increases in QL, CL/CP, sigma d, Kf, and paw weight gain. Postburn pentafraction infusion produced no enduring alterations in any measured parameter as compared with those of animals who received a matched severity scald without pentafraction.

CONCLUSIONS

Pentafraction does not appreciably ameliorate the adverse microcirculatory consequences observed at the site of burn injury.

Analysis of regional hemodynamic regulation in response to scald injury

Ultrasonic probes were placed around dog femoral arteries to record blood flow. Hind paw scalding with boiling water (5 s) caused a marked increase in ipsilateral femoral blood flow that persisted for the 2-h observation period. Contralateral femoral blood flow and systemic and pulmonary vascular resistances were unchanged. Compared to scald only animals, methysergide pretreatment diminished and shortened the femoral vasodilator response to scald (109 +/- 14 vs 243 +/- 27 ml/min at 5 min; 59 +/- 14 vs 191 +/- 31 ml/min at 2 h). Pretreatment with ritanserin, BW A1433U83, atropine, ICI 118551, diphenhydramine, ranitidine, meclofenamate, L-nitro-arginine methyl ester, 3-amino-1,2,4-triazine, and U 37883A had no effect on the increased femoral blood flow response to scald, suggesting this vasodilator response is not dependent upon activation of serotonergic2, adenosineA1, muscarinic, beta 2-adrenergic, histaminergic1 or histaminergic2 receptors, on cyclooxygenase products, endothelium-derived relaxing factor derived from nitric oxide (NO) synthase III, NO derived from NO synthase II, or KATP channels, respectively. Methysergide given after burn immediately reduced the augmented femoral blood flow to preburn levels, suggesting the vasodilator response to scald is mediated through continual activation of local serotonergic1-like receptors, which may be target site(s) for therapeutic interventions to influence burn-induced hemodynamic alterations.

A convincing case for primary repair of penetrating colon injuries

Over the past 14 years, 146 patients with penetrating colon trauma were managed by primary repair with/without resection (PR, n = 55), and by diverting colostomy (DC, n = 91). These groups did not differ in terms of age, ISS (Injury Severity Scale), PATI (Penetrating Abdominal Trauma Index), a-AIS (abdominal Abbreviated Injury Scale), or preoperative hypotension. No intergroup differences were manifested in intra-abdominal complications (fistula/leak, abscess, pancreatitis, intestinal obstruction, wound dehiscence). The percentage of patients who experienced at least one major intra-abdominal complication did not differ statistically when the two groups were compared--12.7% in PR versus 11% in DC--although risk in both groups increased with the additional number of organs injured. Wound infection was significantly higher (p < 0.05) in the PR group (19.6%) compared with the DC group (9.4%). Mortality in the PR and DC groups was 0% and 3.6%, respectively. One hundred and ten patients who underwent elective colostomy closure following trauma had a 9.1% intra-abdominal complication rate and a 3.6% wound infection rate. These risks should be considered when colostomy is selected to manage patients with penetrating colon injury. These data support primary repair of all colon injuries, reserving skin closure for patients with limited collateral damage.

Impact of mandatory nonoperative training on surgical critical care

Since the development of surgical critical care (SCC) as a discrete body of knowledge and its recognition by the American Board of Surgery (ABS), it has been beset by several controversies. One controversy is that the Residency Review Committee (RRC) for Surgery mandated that approved SCC training be 1 year long with no operative experience. A survey was conducted to determine the opinions and experiences on this controversy and others of 498 surgeons who regularly practice SCC. Seventy percent (349) responded and 100% of these held a Certificate of Added Qualifications in SCC. Only 35% of the respondents had completed a critical care fellowship and 61% were either the director or associate director of an ICU. An overwhelming majority (> 90%) believed that SCC should be considered one of the essentials in training surgeons and that the ABS should continue to offer a Certificate of Added Qualifications. Two thirds disagreed with the RRC's ban on operative experience during SCC fellowships and 71% believed that this prohibition limited the pool of surgical applicants to SCC programs. There were no significant differences in the responses between any of the major subgroups. Interestingly, 50% of the respondents who had completed RRC-approved SCC fellowships stated that their fellowship included operative experience.(ABSTRACT TRUNCATED AT 250 WORDS)

Irrigation of the abdominal cavity in the treatment of experimentally induced microbial peritonitis: efficacy of ozonated saline

Ozone is an oxidizing agent possessing potent in vitro microbicidal capacity. This study was designed to address the extent to which irrigation of the contaminated abdominal cavity using a saline solution primed with ozone is effective in reducing morbidity and mortality. Gelatin capsules containing different quantities of a premixed slurry of filtered human fecal material were implanted in the peritoneal cavities of a preliminary series of rats. Three inocula concentrations were selected for later experiments, based upon their ability to produce morbid consequences: (1) high (100% 1-day mortality), (2) medium (70% 3-day mortality, 100% abscess rate in survivors), and (3) low (100% 10-day survival, 100% abscess rate). Fecal and abscess bacteriology were similar in all rats. The peritoneal cavities of 240 rats then underwent fecal-capsule implantation (three groups of 80 rats/inoculum concentration). At celiotomy 4 hours later, equal numbers of rats from each group were randomly assigned to one of four protocols: (1) no irrigation, (2) normal saline irrigation, (3) saline-cephalothin irrigation, and (4) ozonated saline irrigation. Each treatment lasted 5 minutes, using 100 ml of irrigation fluid. Mortality was significantly reduced when, in lieu of no irrigation, any of the irrigation solutions were used. Additionally, ozonated saline statistically proved the most effective irrigating solution for reducing abscess formation in survivors.

The role of endoscopic retrograde cholangiopancreatography: sphincterotomy versus common bile duct exploration as a primary technique in the management of choledocholithiasis

253 patients underwent diagnostic or therapeutic intervention for a presumed diagnosis of choledocholithiasis. In 104 (mean age, 60 years) the diagnosis was confirmed by endoscopic retrograde cholangiopancreatography (ERCP) or common bile duct exploration (CBDE). Of this group, 70 patients first underwent a total of 102 attempts at endoscopic sphincterotomy (ERCP-S). Success (clearing the common duct of stones) was achieved in 43 patients (61%), though an average of 1.5 ERCP-S/patient was required (maximum of four per patient). Of the 27 in whom ERCP-S failed, 20 went on to CBDE, which was successful in 18. Significant morbidity occurred in 12 (17%) ERCP-S patients, including hemorrhage. There were no deaths. Of the 34 patients who first underwent CBDE, 30 were cleared of common duct stones (88%). ERCP-S was subsequently employed to retrieve retained stones in three patients. Significant morbidity was documented in three (9%). No patients required perioperative blood transfusion. There were no deaths. While there is, as expected, a lower initial success rate with ERCP-S than with CBDE, the fact that ERCP-S is a less invasive procedure than is CBDE justifies its preferential utilization. However, patients must be informed that successful ERCP-S may require multiple visits to the endoscopy suite. Furthermore, the morbid consequences of ERCP-S, particularly hemorrhage, cannot be understated.

Prospective alterations in therapy for penetrating abdominal trauma

In a double-blind, randomized study, 170 patients with traumatic perforation of the gastrointestinal tract were administered an advanced-generation cephalosporin. Patients were divided into infection risk groups (< or = 40%, low; 40% to 70%, mid; and > 70%, high) at surgical closure using a logistic regression formula based on four proved risk factors--age, blood replacement, ostomy, and the number of organs injured. Patients in the low group received 2 days of antibiotic therapy; those in the mid to high group received 5 days of antibiotic therapy. Those patients in the low to mid group had primary wound closure; those in the high group had their wounds packed open and closed later. Most of the patients (144 [85%]) were in the low group. Their major and minor infection rates (10% and 12%, respectively) were not significantly different from 145 historic control subjects receiving 5 days of antibiotic therapy (9% major; 14% minor). Patients in the mid to high group showed a greater incidence of major infections (46%) but a similar incidence of minor infections (12%). The results indicate that risk factors can be used to identify low-risk patients who require only short-term antibiotic therapy and primary wound closure. The remaining patients are at greater risk for infection despite prolonged antibiotic therapy and delayed wound closure.