J. Stanley Smith

Prospective Study of Blunt Aortic Injury: Multicenter Trial of the American Association for the Surgery of Trauma

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

Limits of body mass index to detect obesity and predict body composition

Body mass index (BMI) is commonly used to identify obesity. In this study, we determined how accurately BMI could determine body composition and identify obese from non-obese individuals. Fat-free mass and body fat were determined with bioelectrical impedance. Adiposity was calculated as body fat per body mass and as body fat divided by body height (m2). Obesity was defined as a BMI of at least 30 kg/m2 or an amount of body fat of at least 25% of total body mass for men and at least 30% for women. Obesity as defined by percentage of body fat was always present with a BMI of at least 30 kg/m2. However, 30% of men and 46% of women with a BMI below 30 kg/m2 had obesity levels of body fat. The greatest variability in the prediction of percentage of body fat and body fat divided by height (m2) from regression equations using BMI was at a BMI below 30 kg/m2. In conclusion, using impedance-derived body-fat mass as the criterion, people with BMI of at least 30 kg/m2 are obese. However, significant numbers of people with a BMI below 30 kg/m2 are also obese and thus misclassified by BMI. Percent of body fat and body fat divided by height (m2) are predictable from BMI, but the accuracy of the prediction is lowest when the BMI is below 30 kg/m2. Therefore, measurement of body fat is a more appropriate way to assess obesity in people with a BMI below 30 kg/m2.

Validation of several established equations for resting metabolic rate in obese and nonobese people

OBJECTIVE To evaluate several equations for predicting resting metabolic rate against measured values in obese and nonobese people. DESIGN Resting metabolic rate was measured with indirect calorimetry. Four calculation standards using various combinations of weight, height, and age were used to predict resting metabolic rate: a) Harris-Benedict equation, b) Harris-Benedict equation using adjusted body weight in obese individuals, c) Owen, and d) Mifflin. Main outcome was percentage of subjects whose calculated metabolic rate was outside a +/-10% limit from measured values. Subjects/Setting 130 nonhospitalized adult volunteers grouped by degree of obesity (range of body mass index, 18.8 to 96.8). Statistical Analysis Performed Analysis of proportions was used to determine differences in the percentage of subjects estimated accurately by each equation; alpha was set at 0.05. RESULTS Calculated resting metabolic rate was more than 10% different from measured in 22% of subjects using the Mifflin equation, 33% using the Harris-Benedict equation (P=.05 vs Mifflin), and 35% using the Owen equation (P<.05 vs Mifflin). The error rate using Harris-Benedict with adjusted weight in obesity was 74% (vs 36% in obese subjects using actual weight in the standard Harris-Benedict equation). APPLICATIONS/CONCLUSION Of the calculation standards tested, the Mifflin standard provided an accurate estimate of actual resting metabolic rate in the largest percentage of nonobese and obese individuals and therefore deserves consideration as the standard for calculating resting metabolic rate in obese and nonobese adults. Use of adjusted body weight in the Harris-Benedict equation led to less overestimation by that equation in obese people at the expense of increased incidence of underestimation.

Accelerated nitrogen loss after traumatic injury is not attenuated by achievement of energy balance.

BACKGROUND We wanted to determine if achievement of energy balance decreases myofibrillar protein catabolism and nitrogen loss during posttraumatic catabolic illness. METHODS Surgical intensive care unit of a level I trauma center in a university medical center. Trauma patients expected to be mechanically ventilated for at least 4 days were randomly assigned to one of three parenteral feeding groups: (1) nonprotein calorie group: dextrose and lipid intake equal to measured energy expenditure; (2) total calorie group: dextrose, lipid, and protein intake equal to measured energy expenditure; and (3) hypocaloric group: dextrose and lipid intake equal to 50% of measured energy expenditure. Target protein intake for all groups was 1.7 g/kg body wt. On day 4 of nutrition support, a 24-hour balance study was conducted. Urine urea and total nitrogen production, 3-methylhistidine excretion, energy expenditure, and substrate utilization were measured. RESULTS Despite significant differences in nonprotein and total calorie balance among the groups, nitrogen loss, nitrogen balance, and catabolic rate were not significantly different. Nitrogen loss correlated with catabolic rate but not with energy expenditure or energy balance. Catabolic rate was associated with energy expenditure but not with energy balance. Nitrogen loss was positively correlated with the percentage of nonprotein energy expenditure met by nonprotein calorie intake. CONCLUSIONS Achievement of energy balance (nonprotein or total energy) failed to decrease catabolic rate or nitrogen loss acutely in multiple trauma patients. Provision of caloric intake equal to energy expenditure does not seem necessary during the acute phase of posttraumatic catabolic illness.

Office-based cryoablation of breast fibroadenomas with long-term follow-up.

Abstract:  Approximately 10% of women will experience a breast fibroadenoma in their lifetime. Cryoablation is a new treatment that combines the better attributes of the current standards: surveillance and surgery. It is a minimally invasive office‐based procedure that is administered without the use of general anesthesia, involving minimal patient discomfort and little to no scarring. This work aimed to establish the long‐term (2–3 years) efficacy, safety, and satisfaction of the procedure, as well as the impact of cryoablation on mammogram and ultrasound images. Thirty‐seven treated fibroadenomas were available for assessment with an average follow‐up period of 2.6 years. Of the original 84% that were palpable prior to treatment, only 16% remained palpable to the patient as of this writing. Of those fibroadenomas that were initially ≤2.0 cm in size, only 6% remained palpable. A median volume reduction of 99% was observed with ultrasound. Ninety‐seven percent of patients and 100% of physicians were satisfied with the long‐term treatment results. Mammograms and ultrasounds showed cryoablation produced no artifact that would adversely affect interpretation. Cryoablation for breast fibroadenomas has previously been reported as safe and effective both acutely and at the 1‐year follow‐up mark, and thus has been implemented as a treatment option. At long‐term follow‐up, cryoablation as a primary therapy for breast fibroadenomas demonstrates progressive resolution of the treated area, durable safety, and excellent patient and physician satisfaction. The treatment is performed in an office setting rather than an operating room, resulting in a cost‐effective and patient‐friendly procedure. Cryoablation should be considered a preferred option for those patients desiring definitive therapy for their fibroadenomas without surgical intervention. 

Nonoperative management of the ruptured spleen: A revalidation of criteria

BACKGROUND Our goal was to revalidate this institutions original criteria for safe nonoperative management of splenic injury. METHODS This was a prospective series between October 1991 and December 1995 entering all patients with splenic injury to a modified algorithm. Patients were taken to the operating room if hemodynamically unstable (systolic blood pressure less than 90 mm Hg; pulse greater than 110 beats per minute) after 2 liters of fluid resuscitation, positive abdominal examination findings, American Association for the Surgery of Trauma Organ Injury Scale Grade IV or V injuries by computed tomographic scan (unless younger than 15 years old), or associated severe head injuries (unless younger than 15 years old), or age greater than 55. The remainder of the patients were closely observed. RESULTS One hundred seventy-three patients were entered-six were excluded by death before operating room salvage, and one was excluded because of operation for a ruptured thoracic aorta. Therefore 166 patients were reviewed. Seventy splenectomies and 18 splenorrhaphies were performed, and 78 patients were treated nonoperatively (58% splenic salvage). Two failures occurred in the nonoperative group: a 16-year-old with a grade IV hilar injury was operated on on the eighth day after injury because of a continually falling hematocrit, and a 25-year-old with unresolved tachycardia was operated on at 6 hours (97% success rate). The patients in the operative group had a greater severity of injury as determined by mean Injury Severity Score of 32, 18 deaths, a mean transfusion requirement of 14 units of blood compared with mean injury severity score of 21, two deaths from brain injury, and no transfusions given in 58 of the 78 nonoperative cases. CONCLUSIONS Prospectively applied, these guidelines allow the safe nonoperative management of patients with blunt splenic injury.

Tumor necrosis factor mediates impaired wound healing in chronic abdominal sepsis.

BACKGROUND The role of systemic tumor necrosis factor (TNF) as a mediator of impaired wound healing in sepsis is unclear. The purpose of this study was to examine the effects of a specific TNF antagonist (TNFbp) on wound healing during chronic abdominal sepsis. METHODS Male Sprague-Dawley rats were divided into four groups: control, control + TNFbp, sepsis, and sepsis + TNFbp. Saline (1.0 mL) or TNFbp (1 mg/kg, 1.0 mL) was injected subcutaneously daily, polyvinylalcohol (PVA) sponge implants were placed in subcutaneous pockets, and sepsis was induced by creation of a chronic, intra-abdominal abscess. Sponge implants were removed on day 5 and examined histologically. Granulation tissue infiltration and quality (connective tissue, cellularity, vascularity) were scored on a scale from 1 to 4 in a blinded fashion. RESULTS Septic mortality (19 vs. 25%) was not influenced by TNFbp. Granulation tissue penetration and quality were decreased in septic animals. The administration of TNFbp significantly attenuated the effects of sepsis on granulation tissue histology, but not to control levels. CONCLUSIONS These studies provide evidence that TNF contributes to the impaired wound healing observed in this model of chronic abdominal sepsis.

Relative association of fever and injury with hypermetabolism in critically ill patients

The purpose of this study was to determine the association of injury type (trauma, surgery, medical disease), systemic inflammatory response syndrome (SIRS) and fever with the degree of hypermetabolism in critically ill patients. Medical records of 204 critically ill, mechanically ventilated injured, surgical and medical patients were reviewed for indirect calorimetry and associated data. Analysis of variance and covariance was used to test the effects of injury, fever and SIRS on the degree of hypermetabolism. All injury types were found to be hypermetabolic. Analysis of variance of hypermetabolism with injury type and presence of fever as main effects revealed a significant increase in hypermetabolic response from fever, of similar magnitude across all injury types. Subjects with SIRS were significantly more hypermetabolic than subjects without SIRS. However, analysis of variance indicated no effect for SIRS but a significant effect for fever in increasing the hypermetabolic response. It is concluded that fever portends a magnification of the hypermetabolic response, being similar across injury types. SIRS does not identify hypermetabolic patients independent of fever. The host response to injury, not the injury itself, determines metabolic rate in critically ill patients. Neither SIRS nor injury type should be used to classify hypermetabolic states without stratifying for presence of fever.

Is the anteroposterior cervical spine radiograph necessary in initial trauma screening

The usefulness of the anteroposterior (AP) radiograph of the cervical spine in contributing to the diagnosis of cervical spine injuries in the acute trauma patient was examined in a retrospective study. All cases of cervical spine fracture or dislocation seen at a level I trauma center over a 3-year period and at a rehabilitation center over a 10-year period were reviewed. The lateral radiograph, open-mouth odontoid radiograph, and AP radiograph of each case were sequentially examined by a neuroradiologist (blinded to the original diagnosis) to determine the contribution of each view in making a diagnosis of cervical spine injury. Results of these reviews showed that there were no cases of cervical spine injury evident on the AP view without an obvious corresponding abnormality on the lateral or open-mouth view. It was concluded that the AP view could be dropped from the initial screening radiographic study of the cervical spine in the trauma patient. Only an adequate lateral view and open-mouth odontoid view would then be necessary to initially evaluate the cervical spine in the trauma patient, and decisions to obtain further studies could be based safely on only the lateral and open-mouth views.

When is air medical service faster than ground transportation

The purpose of this study was to mathematically define a distance or travel-time interval in which air medical evacuation would benefit the patient more than ground transport. The authors derived mathematical formulas from known variables (ground travel, extrication and rendezvous times) and fixed averages (on-scene time, lift-off time, and speeds) and used those formulas to test actual flights for appropriateness. The formulas were: [formula: see text] where Y = ground travel time; R = rendezvous time; Z = extrication time; D = distance to scene (km); and X = air travel time. The formulas provide a guide to prospectively determine the legitimacy of air medical transport. They can also be used retrospectively as a guide for quality assurance purposes. During this study of 123 consecutive scene flights, helicopter benefitted all the entrapped patients but only one-third of non-entrapped patients. Of 44 flights from areas with known ground times, helicopter transport benefitted 14 of 16 entrapped, five of 16 non-entrapped, but only three of 17 rendezvous.