Edgardo S. Salcedo

Dynamic lung mechanics in late-stage emphysema before and after lung volume reduction surgery

This study evaluated the effects of lung volume reduction surgery (LVRS) on the heterogeneity of lung function in awake, late-stage emphysema patients with measurements taken before and after full recovery from LVRS. We assessed standard clinical measures of lung function and functional heterogeneity in six awake, late-stage emphysema patients before and 6 months after LVRS. Functional heterogeneity was quantified by measuring dynamic inspiratory resistance (R(L)(insp)) and elastance (E(L)(insp)) over a frequency range that included normal breathing ( approximately 0.33-8 Hz). Since LVRS involves targeted resection of emphysematous regions of the lung, we hypothesized that emphysema patients would be functionally more homogeneous post-LVRS. We also compared our measures of functional heterogeneity with indices of anatomic heterogeneity and severity using high-resolution computed tomography (HRCT). After LVRS, 6 min walk distance increased by 22% (940+/-91 versus 1158+/-299, p=0.031) and recoil pressure at TLC increased (9.0+/-2.0 versus 14+/-5, p=0.031), but changes in R(L)(insp) and E(L)(insp) varied greatly between subjects. A measure of anatomic severity quantified using HRCT positively correlated with airway resistance (r(s)=0.89, p=0.048). These results suggest that subjects with more severe disease as assessed by HRCT criteria had reduced overall effective airway caliber consequent to active airway constriction, reduced parenchymal tethering, and/or loss of parallel lung units. Furthermore, LVRS may not necessarily improve lung function via a substantial reduction in mechanical heterogeneity.

Level I academic trauma center integration as a model for sustaining combat surgical skills: The right surgeon in the right place for the right time.

INTRODUCTION As North Atlantic Treaty Organization (NATO) countries begin troop withdrawal from Afghanistan, military medicine needs programs for combat surgeons to retain the required knowledge and surgical skills. Each military branch runs programs at various Level I academic trauma centers to deliver predeployment training and provide a robust trauma experience for deploying surgeons. Outside of these successful programs, there is no system-wide mechanism for nondeploying military surgeons to care for a high volume of critically ill trauma patients on a regular basis in an educational environment that promotes continued professional development. We hypothesize that fully integrated military-civilian relationship regional Level I trauma centers provide a surgical experience more closely mirroring that seen in a Role III hospital than local Level II and Level III trauma center or medical treatment facilities. METHODS We characterized the Level I trauma center practice using the number of trauma resuscitations, operative trauma/acute care surgery procedures, number of work shifts, operative density (defined as the ratio of operative procedures/days worked), and frequency of educational conferences. The same parameters were collected from two NATO Role III hospitals in Afghanistan during the peak of Operation Enduring Freedom. Data for two civilian Level II trauma centers, two civilian Level III trauma centers, and a Continental United States Military Treatment Facility without trauma designation were collected. RESULTS The number of trauma resuscitations, number of 24-hour shifts, operative density, and educational conferences are shown in the table for the Level I trauma center compared with the different institutions. Civilian center trauma resuscitations and operative density were highest at the Level I trauma center and were only slightly lower than what was seen in Afghanistan. Level II and III trauma centers had lower numbers for both. The Level I trauma center provided the most frequent educational opportunities. CONCLUSION In a Level I academic trauma center integrated program, military and civilian surgeons have the same clinical and educational responsibilities: rounding and operating, managing critical care patients, covering trauma/acute care surgery call, and mentoring surgery residents in an integrated residency program. The Level I trauma center experience most closely mimics the combat surgeon experience seen at NATO Role III hospitals in Afghanistan compared with other civilian trauma centers. At high-volume Level I trauma centers, military surgeons will have a comprehensive trauma practice, including dedicated educational opportunities. We recommend integrated programs with Level I academic trauma centers as the primary mechanism for sustaining military combat surgical skills in the future.

Therapeutic Anticoagulation for Isolated Calf Deep Vein Thrombosis

IMPORTANCE Deep vein thrombosis (DVT) isolated to the calf veins (distal to the popliteal vein) is frequently detected with duplex ultrasonography and may result in proximal thrombosis or pulmonary embolism (PE). OBJECTIVE To evaluate whether therapeutic anticoagulation is associated with a decreased risk for proximal DVT or PE after diagnosis of an isolated calf DVT. DESIGN, SETTING, AND PARTICIPANTS All adult patients with ultrasonographic detection of an isolated calf DVT from January 1, 2010, to December 31, 2013, at the Vascular Laboratory of the University of California, Davis, Medical Center were included. Patients already receiving therapeutic anticoagulation and those with a chronic calf DVT, a contraindication to anticoagulation, prior venous thromboembolism within 180 days, or diagnosis of a PE suspected at the time of calf DVT diagnosis were excluded. Data were analyzed from August 18, 2015, to February 14, 2016. EXPOSURES Intention to administer therapeutic anticoagulation. MAIN OUTCOMES AND MEASURES Proximal DVT or PE within 180 days of the diagnosis of the isolated calf DVT. RESULTS From 14 056 lower-extremity venous duplex studies, we identified 697 patients with an isolated calf DVT and excluded 313 of these. The remaining 384 patients were available for analysis (222 men [57.8%]; 162 women [42.2%]; mean [SD] age, 60 [16] years). The calf DVT involved an axial vein (anterior tibial, posterior tibial, or peroneal) in 243 patients (63.2%) and a muscular branch (soleus or gastrocnemius) in 215 (56.0%). Physicians attempted to administer therapeutic anticoagulation in 243 patients (63.3%), leaving 141 control participants. Proximal DVT occurred in 7 controls (5.0%) and 4 anticoagulation recipients (1.6%); PE, in 6 controls (4.3%) and 4 anticoagulation recipients (1.6%). Therapeutic anticoagulation was associated with a decreased risk for proximal DVT or PE at 180 days (odds ratio [OR], 0.34; 95% CI, 0.14-0.83) but an increased risk for bleeding (OR, 4.35; 95% CI, 1.27-14.9), findings that persisted after adjustment for confounding factors (ORs, 0.33 [95% CI, 0.12-0.87] and 4.87 [95% CI, 1.37-17.3], respectively) and sensitivity analyses. CONCLUSIONS AND RELEVANCE Rates of proximal DVT or PE are low after isolated calf DVT. Therapeutic anticoagulation is associated with a reduction of these outcomes but an increase in bleeding.

Prehospital hypertonic fluid resuscitation for trauma patients: A systematic review and meta-analysis

BACKGROUND Prehospital assessment of a patient’s circulation status and appropriate resuscitation with intravenous fluids plays a critical role in patients with obvious hemorrhage or systolic blood pressure below 90 mm Hg. OBJECTIVES We assessed the efficacy and safety of prehospital administration of crystalloids or colloids to improve the survival rate of trauma patients with acceptable safety profile. DATA SOURCES We searched SCOPUS, Embase, TRIP database, Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and PubMed as per search protocol from January 1, 1900 to February 12, 2015. STUDY ELIGIBILITY CRITERIA All randomized controlled trials were considered. PARTICIPANTS AND INTERVENTIONS All patients had penetrating or blunt trauma, excluding traumatic brain or thermal injuries. At least one of the comparators should be a crystalloid or colloid. STUDY APPRAISAL AND SYNTHESIS METHODS Detailed search strategy was developed and utilized. Duplicates were removed from the search results. We, the co-first authors (C.d.C. and F.G.), independently reviewed the article titles and abstracts to assess eligibility. Eligible articles were downloaded for full text review to determine inclusion in the review and analysis. We (C.d.C. and F.G.) performed a methodological quality assessment of each included article. The primary outcome was mortality. The secondary outcomes included adverse events, infections, multiple organ dysfunction score, and length of stay at the hospital. Heterogeneity was measured by I 2 value. An I 2 value greater than 50% was considered to be substantial heterogeneity. Fixed effect analysis and random effect analysis were performed when needed. RESULTS A total of nine trials (3,490 patients) were included in the systematic review, and six trials were included in meta-analyses. There were no significant differences between hypertonic saline with dextran and lactated Ringer’s solution in 1 day using two studies (2.91; 95% CI, 0.58–14.54; p = 0.19) and 28- to 30-day survival rates using another two studies (1.47; 95% CI, 0.30–7.18; p = 0.63). Adding dextran to hypertonic saline did not increase the survival rate (0.94; 95% CI, 0.65–1.34; p = 0.71). Overall, complications were comparable between all groups. LIMITATIONS The quality of some of the included studies is not optimal. CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS There is no beneficial effect of hypertonic saline with or without dextran in general traumatic patients. Further trials to evaluate its benefit in patients with penetrating trauma requiring surgery are warranted. LEVEL OF EVIDENCE Systematic review and meta-analysis, level I.

Design of a cost-effective, hemodynamically adjustable model for resuscitative endovascular balloon occlusion of the aorta (REBOA) simulation

ABSTRACT Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an adjunct technique for salvaging patients with noncompressible torso hemorrhage. Current REBOA training paradigms require large animals, virtual reality simulators, or human cadavers for acquisition of skills. These training strategies are expensive and resource intensive, which may prevent widespread dissemination of REBOA. We have developed a low-cost, near-physiologic, pulsatile REBOA simulator by connecting an anatomic vascular circuit constructed out of latex and polyvinyl chloride tubing to a commercially available pump. This pulsatile simulator is capable of generating cardiac outputs ranging from 1.7 to 6.8 L/min with corresponding arterial blood pressures of 54 to 226/14 to 121 mmHg. The simulator accommodates a 12 French introducer sheath and a CODA balloon catheter. Upon balloon inflation, the arterial waveform distal to the occlusion flattens, distal pulsation within the simulator is lost, and systolic blood pressures proximal to the balloon catheter increase by up to 62 mmHg. Further development and validation of this simulator will allow for refinement, reduction, and replacement of large animal models, costly virtual reality simulators, and perfused cadavers for training purposes. This will ultimately facilitate the low-cost, high-fidelity REBOA simulation needed for the widespread dissemination of this life-saving technique.

Characteristics of chest wall injuries that predict postrecovery pulmonary symptoms: A secondary analysis of data from a randomized trial.

BACKGROUND Although thoracic trauma is common, little is known about which factors lead to poor functional outcomes. We sought to determine which characteristics of chest wall injury predict postrecovery pulmonary symptoms or health-related quality of life. METHODS We conducted a secondary analysis of data from a randomized trial involving patients with chest wall injuries at a Level I trauma center between December 2007 and July 2012. We evaluated the overall severity of the chest wall injury—characterized primarily by the number of fractured ribs—and rib fracture location (upper, middle, and lower; anterior, lateral, and posterior) as predictors of patient-reported outcomes 60 days after injury: dyspnea burden (0–40), Modified Medical Research Council Dyspnea Scale (MMRC) (0–4), St. George’s Respiratory Questionnaire (SGRQ), and normalized Medical Outcomes Study Short-Form 36 (SF-36) scores. RESULTS Of 189 evaluable subjects, the mean (SD) number of fractured ribs was 5 (4). The number of fractured ribs was not associated with dyspnea burden, MMRC, or SGRQ scores. After adjustment for confounders, each additional fractured rib was associated with worse SF-36 Physical Functioning and Bodily Pain scores (−0.6 units [95% confidence interval (CI), −1.1 to 0.0] and −0.8 units [95% CI, −1.3 to −0.2], respectively). Lower rib fractures were associated with worse dyspnea burden (3.4 units; 95% CI, 1.0–5.9), MMRC score (0.4 units; 95% CI, 0.0–0.8), and SF-36 Physical Functioning, Role–Physical, Role–Emotional, and Physical Component Summary scores (−4 units [95% CI, −8 to 0], −5 units [95% CI, −8 to −1], −4 units [95% CI, −8 to 0], and −4 units [95% CI, −7 to −1], respectively). CONCLUSION The overall anatomic severity of chest wall injuries does not predict worse dyspnea symptoms 60 days after injury, but it does predict increased patient perceptions of pain and physical function limitations. Lower rib fractures predict both persistent respiratory symptoms and perception of decreased overall health. LEVEL OF EVIDENCE Prognostic/epidemiologic study, level III.

Arterial phase CT for the detection of splenic injuries in blunt trauma: would it improve clinical outcomes?

OBJECTIVE To determine if the addition of an arterial phase abdominal computed tomography (CT) improves clinical outcomes in patients with blunt splenic injuries. METHODS Retrospective review of patients who underwent CT of the abdomen revealing splenic injuries. Clinical management in these patients was determined. RESULTS Fifty-one of three thousand five hundred twenty-five patients had splenic injuries. Twenty-five patients underwent nonsurgical management, and 3 failed. The theoretical additional arterial phase resulted in a 62% increase in mean effective dose compared to the portal venous phase alone. CONCLUSIONS Routine use of arterial phase CT in blunt trauma patients may not be warranted as there is minimal improvement in outcomes.

When are CT angiograms indicated for patients with lower extremity fractures? A review of 275 extremities.

BACKGROUND Computed tomography angiogram (CTA) is frequently utilized to detect vascular injuries even without examination findings indicating a vascular injury. We had the following hypotheses: (1) a CTA for lower extremity fractures with no clinical signs of a vascular injury is not indicated, and (2) fracture location and pattern would correlate with the risk of a vascular injury. METHODS A retrospective review was conducted on patients who had an acute lower extremity fracture(s) and a CTA. Their charts were reviewed for multiple factors including the presence or absence of hard or soft signs of a vascular injury, soft tissue status, and fracture location/pattern. Every CTA radiology report was reviewed and any vascular intervention or amputation resulting from a vascular injury was recorded. Statistical analysis was performed. RESULTS Of the 275 CTAs of fractured extremities reviewed, 80 (29%) had a positive CTA finding and 16 (6%) required treatment. A total of 109 (40%) of the extremities had no hard or soft signs; all had normal CTAs. Having at least one hard or soft sign was a significant risk factor for having a positive CTA. An open fracture, isolated proximal third fibula fracture, distal and shaft tibia fractures, and the presence of multiple fractures in one extremity were also associated with an increased risk for having a positive CTA. CONCLUSION We found no evidence to support the routine use of CTAs to evaluate lower extremity fractures unless at least one hard or soft sign is present. The presence of an open fracture, distal tibia or tibial shaft fractures, multiple fractures in one extremity, and/or an isolated proximal third fibula fracture increases the risk of having a finding consistent with a vascular injury on a CTA. Only 6% of the cases required treatment, and all of them had diminished or absent distal pulses on presentation. LEVEL OF EVIDENCE Diagnostic test, level III.

Randomized controlled trial comparing dynamic simulation with static simulation in trauma.

BACKGROUND Current general surgery residents have limited exposure to open trauma operative cases. Simulation supplements variable rotation volume and provides experience with critical but rarely performed procedures. Open simulation classically focuses on static models with anatomic accuracy but lacks practicality when hemorrhage control is the lifesaving maneuver. We sought to evaluate whether training on a dynamic simulator, while much less expensive than training on a static cadaver, might be at least as effective in training surgery residents to expeditiously place temporary vascular shunts (TVSs). METHODS Our research team developed an inexpensive, reusable dynamic simulator with ongoing hemorrhage to instruct trainees in the steps of TVS placement. We enrolled 54 general surgery residents in a noninferiority randomized controlled trial comparing training of TVS placement on the dynamic simulator (n = 28) versus a cadaver arm (n = 26). After standardized video didactics, trainees practiced on either the simulator or cadaver arm. After the trainees achieved competency, they were tested on placing a TVS for a live swine femoral artery injury. Two blinded trauma surgeons evaluated the recorded performances. RESULTS Residents did not differ in baseline characteristics between groups, and all residents in both groups successfully completed the TVS placement test. Subjects trained on the simulator placed the TVS faster than those trained on a cadaver (584 seconds vs. 751 seconds; difference, +167 seconds faster; 90% confidence interval [CI], +52 to +282 seconds), with a trend toward faster time to hemorrhage control (110 seconds vs. 148 seconds; difference, +38 seconds faster; 90% CI, −8 to +84). There was no significant difference in Objective Structured Assessment of Technical Skills scores (3.72 vs. 3.44; difference, +0.27 units better; 90% CI, −0.04 to +0.59). CONCLUSION Training on a dynamic simulator resulted in noninferior time to completion of vascular shunt placement compared with training on a cadaver. The addition of dynamic hemorrhage to simulators might inexpensively augment trauma skills training.

Evaluation of cystic duct patency: comparison of functional MR cholangiography with gadoxetate disodium and hepatobiliary scintigraphy in suspected acute cholecystitis

PURPOSE This study aims to compare assessment of cystic duct patency between gadoxetate disodium MRI and hepatobiliary scintigraphy. MATERIALS AND METHODS We performed a prospective study of patients who underwent gadoxetate disodium MRI within 16 h of scintigraphy. RESULTS The gallbladder filled on MRI and scintigraphy in 8 patients, none with acute cholecystitis. The mean time to gallbladder filling was 14.6 and 18.9 min for MRI and scintigraphy, respectively. The gallbladder did not fill on both MRI and scintigraphy in 3 patients, all of whom had acute cholecystitis. CONCLUSION Evaluation of cystic duct patency using gadoxetate disodium MRI is comparable to hepatobiliary scintigraphy.