The Effect of Stepping Back From the X-Ray Table on Operator Radiation Exposure.

ABSTRACT: Background: Nearly all radiation safety courses teach that scatter radiation around the x-ray table falls with the inverse of the distance from the imaging site. Humans, however, are complex x-ray reflectors and the application of the inverse square law to clinical imaging is only assumed. Methods: We measured scatter radiation at two positions where staff commonly stand around the x-ray table. Using an anthropomorphic human phantom, human and pig cadavers, and a glass sphere, we measured scatter radiation levels in each position, and then 2- and 3-fold the distance from the imaging site. We compared the measured scatter radiation to that predicted by the common inverse square law and a more detailed geometric inverse square law. Results: In all but the glass sphere, scatter radiation was much higher below the table (68-74% of all scatter radiation, depending on model and position) than above the table (26-32% of scatter radiation, p < 0.01). Scatter radiation fell with increasing distance from the table, but above the table both inverse square laws significantly over-estimated the benefit of stepping back (19-93% overestimation by geometric inverse square law at 2-fold distance, 14-46% at 3-fold). In addition, a pelvis in the phantom appeared to cause significant scatter radiation field anomalies at the angiographer position. Conclusion: Stepping back from the table does not reduce scatter radiation levels as much as the inverse square law predicts. The geometric inverse square law best predicts the reduction in scatter radiation below the table, but above the table it too overestimates the benefit of stepping back. The irregularity of the scatter radiation field should be taken into account by scatter radiation shielding systems.

Impact of Genitourinary Injuries on Patients Requiring an Emergency Laparotomy for Trauma.

Introduction In patients having emergency abdominal surgery for trauma, the presence of urologic injury tends to increase mortality and morbidity. Methods This retrospective study evaluated patients requiring emergency surgery for abdominal trauma at a Level 1 Trauma Center over 30 years (1980-2010). Special attention was given to patients with concomitant genitourinary (GU) injuries. Results Of 1105 patients requiring an emergency laparotomy for trauma, 242 (22%) had urologic injuries including kidney 178 (16%), ureter 47 (4%), and bladder 46 (4%). Of the 242 patients, 50 (20%) died early (<48 hours) and 13 (5%) died later, primarily due to infection. A concept of "seven deadly signs" of hypoperfusion was developed. In patients with GU injuries, the presence of any deadly sign of hypoperfusion increased the mortality rate from 4% (6/152) to 63% (56/90), p<0.001. Of the 53 patients having a nephrectomy, 36 (68%) had one or more deadly signs and 27 (75%) died. Of 17 without deadly signs, only 2 (12%) died (p=0.001). Of 167 GU patients receiving blood, 59 (35%) developed infection vs 3/75(4%) in those receiving no blood (p<0.001). Conclusions The presence of deadly signs of severe injury and hypoperfusion on admission was the major factor determining mortality. With a severely injured kidney plus any deadly signs of hypoperfusion, special efforts should be made to avoid a nephrectomy.

Transcatheter Aortic Valve Replacement With the HLT Meridian Valve.

BACKGROUND: While most self-expanding transcatheter valves are repositionable, only one fully retrievable valve is currently available. The Meridian valve is a new self-expanding valve with full retrievability properties. The objective of our study was to evaluate the early feasibility, preliminary safety, and efficacy of transcatheter aortic valve replacement with the HLT Meridian valve (HLT, Inc). METHODS: This was a multicenter early feasibility study including patients with severe aortic stenosis at high surgical risk undergoing transfemoral transcatheter aortic valve replacement with the 25-mm Meridian valve. All serious adverse events were adjudicated by an independent clinical events committee according to Valve Academic Research Consortium-2 criteria. Echocardiography data were assessed by an independent echocardiography core laboratory. RESULTS: A total of 25 patients (mean age, 85±6 years; 80% of men) were included. The valve was successfully implanted in 22 (88%) patients (annulus too large and extreme horizontal aorta in 2 and 1 unsuccessful cases, respectively). Valve retrieval because of an initial nonadequate positioning was attempted and successfully performed in 10 (40%) patients. Echocardiography post-transcatheter aortic valve replacement showed a low mean residual gradient (10±4 mm Hg) and the absence of moderate-severe aortic regurgitation (none-trace and mild aortic regurgitation in 76% and 24% of patients, respectively). Mortality at 30 days was 8%, with no cases of disabling stroke, valve embolization, or major/life-threatening bleeding complications. At 6-month follow-up, the cumulative mortality rate was 12%, with no changes in echocardiographic parameters and no cases of valve dysfunction. The majority of patients (89%) were in New York Heart Association class I-II at 6 months. CONCLUSIONS: Transcatheter aortic valve replacement with the Meridian valve was feasible and associated with acceptable early and 6-month clinical results. Valve retrieval after full valve deployment was successfully performed in all attempted cases, and valve performance was excellent, with low residual gradients, no cases of moderate-severe aortic regurgitation, and none-trace residual aortic regurgitation in the majority of patients. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02838680 (RADIANT-Canada); NCT02799823 (RADIANT-US).

The clinical evaluation of the CADence device in the acoustic detection of coronary artery disease.

The noninvasive detection of turbulent coronary flow may enable diagnosis of significant coronary artery disease (CAD) using novel sensor and analytic technology. Eligible patients (n = 1013) with chest pain and CAD risk factors undergoing nuclear stress testing were studied using the CADence (AUM Cardiovascular Inc., Northfield MN) acoustic detection (AD) system. The trial was designed to demonstrate non-inferiority of AD for diagnostic accuracy in detecting significant CAD as compared to an objective performance criteria (sensitivity 83% and specificity 80%, with 15% non-inferiority margins) for nuclear stress testing. AD analysis was blinded to clinical, core lab-adjudicated angiographic, and nuclear data. The presence of significant CAD was determined by computed tomographic (CCTA) or invasive angiography. A total of 1013 subjects without prior coronary revascularization or Q-wave myocardial infarction were enrolled. Primary analysis was performed on subjects with complete angiographic and AD data (n = 763) including 111 subjects (15%) with severe CAD based on CCTA (n = 34) and invasive angiography (n = 77). The sensitivity and specificity of AD were 78% (p = 0.012 for non-inferiority) and 35% (p < 0.001 for failure to demonstrate non-inferiority), respectively. AD results had a high 91% negative predictive value for the presence of significant CAD. AD testing failed to demonstrate non-inferior diagnostic accuracy as compared to the historical performance of a nuclear stress OPC due to low specificity. AD sensitivity was non-inferior in detecting significant CAD with a high negative predictive value supporting a potential value in excluding CAD.

Coronary Artery Disease in Patients With Out-of-Hospital Refractory Ventricular Fibrillation Cardiac Arrest.

BACKGROUND: The prevalence of coronary artery disease (CAD) among patients with refractory out-of-hospital (OH) ventricular fibrillation (VF)/ventricular tachycardia (VT) cardiac arrest is unknown. OBJECTIVES: The goal of this study was to describe the prevalence and complexity of CAD and report survival to hospital discharge in patients experiencing refractory VF/VT cardiac arrest treated with a novel protocol of early transport to a cardiac catheterization laboratory (CCL) for extracorporeal life support (ECLS) and revascularization. METHODS: Between December 1, 2015, and December 1, 2016, consecutive adult patients with refractory OH VF/VT cardiac arrest requiring ongoing cardiopulmonary resuscitation were transported by emergency medical services to the CCL. ECLS, coronary angiography, and percutaneous coronary intervention were performed, as appropriate. Functionally favorable survival to hospital discharge (Cerebral Performance Category 1 or 2) was determined. Outcomes in a historical comparison group were also evaluated. RESULTS: Sixty-two (86%) of 72 transported patients met emergency medical services transport criteria. Fifty-five (89%) of the 62 patients met criteria for continuing resuscitation on CCL arrival; 5 had return of spontaneous circulation, 50 received ECLS, and all 55 received coronary angiography. Forty-six (84%) of 55 patients had significant CAD, 35 (64%) of 55 had acute thrombotic lesions, and 46 (84%) of 55 had percutaneous coronary intervention with 2.7 ± 2.0 stents deployed per patient. The mean SYNTAX score was 29.4 ± 13.9. Twenty-six (42%) of 62 patients were discharged alive with Cerebral Performance Category 1 or 2 versus 26 (15.3%) of 170 in the historical comparison group (odds ratio: 4.0; 95% confidence interval: 2.08 to 7.7; p < 0.0001). CONCLUSIONS: Complex but treatable CAD was prevalent in patients with refractory OH VF/VT cardiac arrest who also met criteria for continuing resuscitation in the CCL. A systems approach using ECLS and reperfusion seemed to improve functionally favorable survival.

A novel approach to diagnosing coronary artery disease: acoustic detection of coronary turbulence.

Atherosclerotic disease within coronary arteries causes disruption of normal, laminar flow and generates flow turbulence. The characteristic acoustic waves generated by coronary turbulence serve as a novel diagnostic target. The frequency range and timing of microbruits associated with obstructive coronary artery disease (CAD) have been characterized. Technological advancements in sensor, data filtering and analytic capabilities may allow use of intracoronary turbulence for diagnostic and risk stratification purposes. Acoustic detection (AD) systems are based on the premise that the faint auditory signature of obstructive CAD can be isolated and analyzed to provide a new approach to noninvasive testing. The cardiac sonospectrographic analyzer, CADence, and CADScore systems are early-stage, investigational and commercialized examples of AD systems, with the latter two currently undergoing clinical testing with validation of accuracy using computed tomography and invasive angiography. Noninvasive imaging accounts for a large percentage of healthcare expenditures for cardiovascular disease in the developed world, and the growing burden of CAD will disproportionately affect areas in the developing world. AD is a portable, radiation-free, cost-effective method with the potential to provide accurate diagnosis or exclusion of significant CAD. AD represents a model for digital, miniaturized, and internet-connected diagnostic technologies.

Audible Coronary Artery Stenosis.

OBJECTIVE: Hemodynamically significant coronary artery stenoses generate turbulent blood flow patterns that manifest as intracoronary murmurs. This study aims to evaluate the performance of modern acoustic detection of these murmurs by acoustic signals captured from patients undergoing gold standard comparative coronary angiography. METHODS: We prospectively studied 156 patients undergoing elective coronary angiography, excluding those with acute coronary syndrome, prior chest surgery, or significant valvular disease. Acoustic signals were captured before arterial access. Angiographic degree of stenosis in each coronary artery was graded blinded to clinical and acoustic data. Acoustic data were analyzed blinded to clinical and angiographic data, categorizing subjects as "normal," "diseased," or "inconclusive." Of 156 patients examined, 123 generated analyzable data. RESULTS: Angiographically significant stenosis (≥50%) prevalence was 52% (18%, 23%, 11% with 1-, 2-, 3-vessel disease, respectively). Acoustic detection sensitivity and specificity for stenosis ≥50% in any vessel were 0.70 and 0.80, respectively (negative predictive value, 0.71; positive predictive value, 0.79). Acoustic detection optimally identified stenosis ≥50% with an area under the curve of 0.75. For stenosis ≥50% in major vessels only (left main, proximal-mid left anterior descending, proximal-mid circumflex, proximal-mid right coronary), prevalence was 46%; sensitivity and specificity were 0.72 and 0.76, respectively (negative predictive value, 0.76; positive predictive value, 0.72; area under the curve, 0.76). CONCLUSIONS: Acoustic signal patterns and modern analysis techniques may be used to identify intracoronary murmurs generated by hemodynamically significant coronary artery stenoses in all major vessels. Further investigation is warranted to compare the clinical performance of this modality with current noninvasive approaches that evaluate patients at risk for atherosclerotic and obstructive coronary artery disease.

Impact of inappropriate initial antibiotics in critically ill surgical patients with bacteremia.

BACKGROUND: Bloodstream infections in critically ill patients are associated with mortality as high as 60% and a prolonged hospital stay. We evaluated the impact of inappropriate antibiotic therapy (IAAT) in a critically ill surgical cohort with bacteremia. METHODS: This retrospective study evaluated adults with intensive care unit admission greater than 72 hours and bacteremia. Two groups were evaluated: appropriate antibiotic therapy (AAT) vs IAAT. RESULTS: In 72 episodes of bacteremia, 57 (79%) AAT and 15 (21%) IAAT, mean age was 54 ± 17 years and APACHE II of 17 ± 8. Time to appropriate antibiotics was longer for IAAT (3 ± 5 IAAT vs 1 ± 1 AAT days, P = .003). IAAT was seen primarily with Acinetobacter spp (33% IAAT vs 9% AAT, P = .01) and Enterococcus faecium (26% IAAT vs 7% AAT, P = .03). If 2 or more bacteremic episodes occurred, Acinetobacter spp. was more likely, 32% vs 2%, P = .001. CONCLUSIONS: AAT selection is imperative in critically patients with bacteremia to reduce the significant impact of inappropriate selection. Repeated episodes of bacteremia should receive special attention.

Hydromorphone vs fentanyl for epidural analgesia and anesthesia.

BACKGROUND: Epidural analgesia/anesthesia is used during surgery because it dramatically relieves pain and attenuates the stress response. Because limited data exist regarding the relative merits of hydromorphone (HM) and fentanyl (FENT), the objective was to determine which was more safe and effective. METHODS: Prospective case-matched, observational study evaluated elective surgery patients: 30 HM and 60 FENT. Variables were measured perioperatively. RESULTS: Of the 90 patients, mean age was 52 years; simplified acute physiology score was 26 ± 10; and American Society of Anesthesiologists score was 2.4 HM vs 2.7 FENT, P = .03. HM patients were more apt to be excessively sedated (16% HM vs 1% FENT, P = .007) and have poor mental unresponsiveness (6% HM vs 0% FENT, P = .04). The incidence of hypotension was not different, 76% HM vs 80% FENT, not significant. CONCLUSIONS: In a closely case-matched population, FENT caused less excessive sedation and unresponsiveness. FENT patients had better intraoperative urine output and tended to have less repeated episodes of hypotension.

Impact of minimizing diagnostic blood loss in the critically ill.

BACKGROUND: The use of a small-volume phlebotomy tube (SVPT) versus conventional-volume phlebotomy tube (CVPT) has led to a decrease in daily blood loss. Blood loss due to phlebotomy can lead ultimately to decreased rates of anemia and blood transfusions, which can be important in the critically ill patient. METHODS: We compared SVPT vs CVPT retrospectively in critically ill adult patients age ≥18 years admitted to a surgical intensive care unit for ≥48 hours. CVPT were evaluated from January 2011 to May 2011 and SVPT from June 2012 to October 2012. RESULTS: Amount of blood drawn for laboratory tests and transfusions were evaluated in 248 patients (116 SVPT vs 132 CVPT). When compared with CVPT, total blood volume removed (mean ± SD) with SVPT was less overall, 174 ± 182 mL vs 299 ± 355 mL, P = .001. Daily blood draws also were less, 22.5 ± 17.3 mL vs 31.7 ± 15.5 mL, P < .001. The units of packed red blood cells given were not significant, 4.4 ± 3.6 units vs 6.0 ± 8.2 units, P = .16. CONCLUSION: The use of SVPT blood sampling led to a decreased amount of blood drawn. Strategies that use SVPT in a larger cohort also may decrease the number of transfusions in selected patients. Every effort should be made to use SVPT.

Hyperbaric oxygen therapy for systemic gas embolism after hydrogen peroxide ingestion.

BACKGROUND: Hydrogen peroxide is a commonly available product and its ingestion has been demonstrated to produce in vivo gas bubbles, which can embolize to devastating effect. OBJECTIVE: We report two cases of hydrogen peroxide ingestion with resultant gas embolization, one to the portal system and one cerebral embolus, which were successfully treated with hyperbaric oxygen therapy (HBO), and review the literature. CASE REPORT: Two individuals presented to our center after unintentional ingestion of concentrated hydrogen peroxide solutions. Symptoms were consistent with portal gas emboli (Patient A) and cerebral gas emboli (Patient B), which were demonstrated on imaging. They were successfully treated with HBO and recovered without event. CONCLUSIONS: As demonstrated by both our experience as well as the current literature, HBO has been used to successfully treat gas emboli associated with hydrogen peroxide ingestion. We recommend consideration of HBO in any cases of significant hydrogen peroxide ingestion with a clinical picture compatible with gas emboli.

Bicarbonate therapy in severely acidotic trauma patients increases mortality.

BACKGROUND: Normally, end-tidal CO(2) is within 2 mm Hg of arterial PO(2) (PaCO(2)). However, if dead space in the lungs increases owing to shock with poor lung perfusion, the arterial-end tidal PCO(2) difference [P(a-ET)CO(2)] increases. We have found that in severely injured patients, P(a-ET)CO(2) of less than 10 mm Hg is associated with survival and P(a-ET)CO(2) of greater than 16 mm Hg is usually fatal. Our initial studies suggested that intravenously administered bicarbonate increases P(a-ET)CO(2). METHODS: This retrospective therapeutic study evaluated the effects of intravenously administered bicarbonate in a cohort of 225 severely acidotic (arterial pH ≤ 7.10) trauma patients who underwent emergency surgery from 1989 through 2011. Patients were divided into groups: early deaths (<48 hours), deaths in the operating room, deaths within 48 hours, and survivors. Winter's formula was defined as PaCO(2) = (HCO(3)) (1.5) + 8 ± 4. RESULTS: Of the 225 patients, the mean (SD) initial arterial pH was 6.92 (0.16) with HCO(3) of 11.0 (3.5) mEq/L. According to the Winter's formula, PaCO(2) should have been 24 (4) mm Hg but actually was 50 (14) mm Hg. In 73 patients, the effect of an average of two to eight vials of bicarbonate increased HCO(3) from 10.5 (3.1) mEq/L to 16.8 (4.0) mEq/L. In addition, PaCO(2) increased from 44 (9) mm Hg to 51 (11) mm Hg and end-tidal CO(2) stayed relatively constant (26 [6] to 25 [5]). This resulted in a increase in P(a-ET)CO(2) from 17 (9) mm Hg to 24 (13) mm Hg, affecting survival. In the final values after resuscitation, the P(a-ET)CO(2) in the 75 patients who survived was 10 (6) mm Hg, while the 103 patients who died in the operating room or within 48 hours of surgery had a P(a-ET)CO(2) of 23 (10) mm Hg (p < 0.001). CONCLUSION: In severely acidotic, critically injured patients, reducing the PaCO(2) to less than 40 mm Hg and decreasing the P(a-ET)CO(2) to 10 (6) mm Hg should be attempted, using as little HCO(3) therapy as possible. Bicarbonate should be given only if severe acidosis persists despite resuscitation and if PaCO(2) levels near those which are appropriate can be obtained. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Impact of evaluating antibiotic concentrations in abdominal abscesses percutaneously drained.

BACKGROUND: Appropriate antibiotic therapy and prompt drainage are essential for optimal results with abdominal abscesses. METHODS: In this prospective study, 47 abdominal abscesses from 42 patients over 2 years who had percutaneous drainage were evaluated. Antibiotic concentrations were evaluated from the abscess fluid and correlated with clinical and microbiologic cure. RESULTS: Only 23% of patients had appropriate antibiotic selection with optimal concentrations for the bacteria recovered. Piperacillin/tazobactam, cefepime, and metronidazole provided adequate concentrations in all except the largest abscesses, whereas fluconazole required higher doses in all abscesses. Vancomycin and ciprofloxacin levels were inadequate in most abscesses. With gram-negative aerobes, the use of appropriate antibiotics resulted in a relatively higher incidence of presumed eradication (100% [4 of 4] vs 75% [9 of 12], P = .26). With ≥ 3 organisms identified, clinical failure was significant (58% vs 13%, P = .01). CONCLUSIONS: For optimal treatment, abdominal abscesses require prompt drainage and properly selected antibiotics at adequate doses. Essential information can be obtained from abscess cultures and their antibiotic concentrations.

Ischemic cardiac complications following G-CSF.

Granulocyte-colony stimulating factor (G-CSF) is commonly used in bone marrow transplant donors to increase the number of circulating progenitor cells. G-CSF has also been studied following myocardial infarction, but concern has been raised about the risks of G-CSF administration in patients with coronary artery disease. We present two cases of ischemic cardiac complications that are likely to be related to administration of G-CSF and provide a contemporary overview of the literature on the cardiovascular risks of G-CSF.

Twelve hundred abscesses operatively drained: an antibiotic conundrum?

BACKGROUND: The incidence of soft tissue infections from antimicrobial-resistant pathogens is increasing. This study evaluated the epidemiology of operatively drained soft tissue abscesses. METHODS: This retrospective study evaluated 1,200 consecutive patients from 2002 to 2008 who underwent incision and drainage (I&D) in the main operating room. Patients were excluded for perirectal or hidradenitis infections. RESULTS: Of 1,200 consecutive cases with an I&D, 1,005 patients had intraoperative cultures. The 1,817 positive isolates included gram-positive aerobes (1,180 [65%]), gram-negative aerobes (207 [11%]), anaerobes (416 [23%]), and fungi (14 [1%]). The most prevalent organism was Staphylococcus aureus, 30% (536), with 80% (431) being methicillin-resistant S aureus (MRSA). MRSA was the predominant organism in all except the breast abscesses. Anaerobes were identified primarily in the breast in diabetics, and in trunk and extremity abscesses in intravenous drug users. The most frequently prescribed empiric antibiotic was ampicillin/sulbactam (66%). The initial empiric antibiotic did not cover MRSA (82%; P < .001), resistant gram-negative aerobes (24%), and anaerobes (26%). CONCLUSION: Gram-positive aerobes plus anaerobes represented approximately 80% of the pathogens in our series, with the anaerobic rates being underestimated. Empiric antibiotics should cover MRSA and anaerobes in patients with superficial abscesses drained operatively.

Intra-cardiopulmonary resuscitation hypothermia with and without volume loading in an ischemic model of cardiac arrest.

BACKGROUND: We investigated the effects of intra-cardiopulmonary resuscitation (CPR) hypothermia with and without volume loading on return to spontaneous circulation and infarction size in an ischemic model of cardiac arrest. METHODS AND RESULTS: Using a distal left anterior descending artery occlusion model of cardiac arrest followed by resuscitation with a total of 120 minutes of occlusion and 90 minutes of reperfusion, we randomized 46 pigs into 5 groups and used myocardial staining to define area at risk and myocardial necrosis. Group A had no intervention. Immediately after return of spontaneous circulation, group B received surface cooling with cooling blankets and ice. Group C received intra-CPR 680+/-23 mL of 28 degrees C 0.9% normal saline via a central venous catheter. Group D received intra-CPR 673+/-26 mL of 4 degrees C normal saline followed by surface cooling after return of spontaneous circulation. Group E received intra-CPR and hypothermia after return of spontaneous circulation with an endovascular therapeutic hypothermia system placed in the right atrium and set at a target of 32 degrees C. Intra-CPR volume loading with room temperature (group C) or iced saline (group D) significantly (P<0.05) decreased coronary perfusion pressure (group C, 12.8+/-4.78 mm Hg; group D, 14.6+/-9.9 mm Hg) compared with groups A, B, and E (20.6+/-8.2, 20.1+/-7.8, and 21.3+/-12.4 mm Hg). Return of spontaneous circulation was significantly improved in group E (9 of 9) compared with groups A plus B and C (10 of 18 and 1 of 8). The percent infarction to the area at risk was significantly reduced with intra-CPR hypothermia in groups D (24.3+/-4.2%) and E (4+/-3.4%) compared with groups A (72+/-5.1%) and B (67.3+/-4.2%). CONCLUSIONS: Intra-CPR hypothermia significantly reduces myocardial infarction size. Elimination of volume loading further improves outcomes.