Faculty Bibliography

AIMS/OBJECTIVE:The commonly used valve-in-valve (VIV) app recommends sizing based on dimensions of both the transcatheter heart valve (THV) and bioprosthetic surgical valve. The implications of hydrodynamic testing to guide VIV sizing are poorly understood. This bench study assessed the hydrodynamic performance of different sizes of self-expanding supra-annular THVs in three different surgical aortic bioprostheses at different implantation depths. METHODS:A small versus medium ACURATE neo (ACn), and a 26 mm versus 29 mm Evolut R were assessed after VIV implantation in 25 mm Mitroflow, Mosaic, and Magna Ease aortic surgical bioprostheses, at three implantation depths (+2 mm, -2 mm, and -6 mm). RESULTS:The medium-sized ACn had lower gradients compared to the small ACn when the THV was implanted high (+2 mm, or -2 mm). The 29 mm Evolut R had lower gradients compared to a 26 mm Evolut R for all implantation depths, except for a depth of -2 mm in the 25 mm Mitroflow. The medium ACn and 29 mm Evolut R had larger effective orifice areas compared to the small ACn and 26 mm Evolut R, respectively. Both Evolut R sizes had acceptable regurgitant fractions (<15%), while both ACn sizes were above the acceptable performance criteria (>15%), at all implantation depths. CONCLUSIONS:Use of a larger self-expanding THV was associated with superior hydrodynamic performance if the THV was implanted high. Hydrodynamic testing can provide additional information to the VIV app to help guide VIV sizing.

OBJECTIVES:Desaturation leading to hypoxemia may occur during rapid sequence intubation (RSI). Apneic oxygenation (AO) was developed to prevent the occurrence of oxygen desaturation during the apnea period. The purpose of this study was to determine if the application of AO increases the average lowest oxygen saturation during RSI when compared to usual care (UC) in the emergency setting. METHODS:A randomized controlled trial was conducted at an academic, urban, Level I trauma center. All patients requiring intubation were included. Exclusion criteria were patients in cardiac or traumatic arrest or if preoxygenation was not performed. An observer, blinded to study outcomes and who was not involved in the procedure, recorded all times, while all saturations were recorded in real time by monitors on a secured server. Two-hundred patients were allocated to receive AO (n = 100) or UC (n = 100) by predetermined randomization in a 1:1 ratio. RESULTS:A total of 206 patients were enrolled. There was no difference in lowest mean oxygen saturation between the two groups (92, 95% confidence interval [CI] = 91 to 93 in AO vs. 93, 95% CI = 92 to 94 in UC; p = 0.11). CONCLUSION:There was no difference in lowest mean oxygen saturation between the two groups. The application of AO during RSI did not prevent desaturation of patients in this study population.

BACKGROUND:Injury severity score, serum lactate, and shock index help the physician determine the severity of injuries present and have been shown to relate to mortality. We sought to determine if an increasing amount of packed red blood cells (PRBCs) given in the first 24hours of admission is an independent predictor of mortality and how it compares to other validated markers. METHODS:A 6-year retrospective, observational study of adult trauma patients was conducted at a level 1 trauma center. Charts were reviewed for demographic data, amount of PRBC received in the first 24hours, injury severity score, shock index, and lactate levels. Subgroups were used to determine if each variable was an independent predictor of mortality. Correlation coefficients and linear regression were used to determine the strength of correlation between each variable and mortality. RESULTS:One hundred fifty-seven patients met criteria over a 6-year period. The average age was 28years, 93% were male, and 86% had penetrating injuries. The average injury severity score, serum lactate, and shock index were 18, 6.1, and 0.9, respectively. The average amount of blood given was 6.7 U. CONCLUSION/CONCLUSIONS:Twenty-four-hour PRBC requirement is both a novel independent predictor of and has the greatest correlation to mortality in adult trauma patients when compared to injury severity score, shock index, and serum lactate.

OBJECTIVE:The main objective of the present study was to examine the perceived versus actual time to intubation (TTI) as an indication to help determine the situational awareness of Emergency Physicians during rapid sequence intubation and, additionally, to determine the physician's perception of desaturation events. METHODS:A timed, observation prospective cohort study was conducted. A post-intubation survey was administered to the intubating physician. Each step of the procedure was timed by an observer in order to determine actual TTI. The number of desaturation events was also recorded. RESULTS:One hundred individual intubations were included. The provider perceived TTI was significantly different and underestimated when compared with the actual TTI (23 s, 95% confidence interval (CI) 20.4-25.49 vs 45.5 s, 95% CI 40.2-50.7, P < 0.001, respectively). Pearson correlation coefficient of perceived TTI to actual TTI was r(2)  = 0.39 (95% CI 0.21-0.54, P < 0.001). The provider perceived desaturation rate was also significantly different from actual desaturation rate (13, 95% CI 3-12 vs 23, 95% CI 13-29, P = 0.05, respectively). The overall time to desaturation was 65.1 s. CONCLUSIONS:Our findings have shown that provider's perception of TTI occurs sooner than actually observed. Also, the providers were less aware of desaturation during the procedure.

BACKGROUND:Biomarkers such as serum lactate, anion gap (AG), and base excess (BE) have been shown to be of use in determining shock in patients with seemingly normal vital signs. We seek to determine if these biomarkers can be used interchangeably in patients with trauma in the emergency setting based on their test characteristics and correlation to each other. METHODS:A prospective observational cohort study was undertaken at an urban level 1 trauma center. Baseline vital signs, point-of-care BE, AG, and serum lactate were recorded in all patients who presented for trauma. Correlation was determined by linear regression model. Overall test characteristics and relative risk were calculated. RESULTS:One hundred patients were enrolled. The median age was 30 years (interquartile range, 24-42 years), and 89% were male. Fifty-three percent of injuries were blunt trauma. Pearson correlation of serum lactate to BE was -0.81 (r(2) = 0.66; 95% confidence interval [CI], 0.53-0.75; P < .001), that of BE to AG was -0.71 (r(2) = 0.5; 95% CI, -0.80 to -0.57; P < .01), and that for serum lactate to AG was 0.71 (r(2) = 0.5; 95% CI, 0.57-0.80; P < .01). CONCLUSIONS:This study demonstrates that the biomarkers have similar test characteristics which may make them interchangeable as indicators for the presence of occult shock in patients with trauma. Lactate and BE correlate well with each other; however, AG was not as strongly correlated with either.

BACKGROUND:Metabolic acidosis has been proposed as the gold standard to define shock in trauma patients. Other studies determine the presence of shock by use of serum lactate. However, not all medical centers have the ability to utilize point-of-care lactate at bedside. OBJECTIVE:This study seeks to determine the relationship between serum lactate and metabolic acidemia in trauma patients, and if metabolic acidemia can be used to guide therapy. We hypothesized that acidemia would be strongly correlated with lactate levels and would be associated with activation of massive transfusion (MT) in the presence of shock in trauma. METHODS:This was a prospective observational cohort study, level II evidence; this study aids in decision-making. Setting was a Level I academic, urban trauma center. The study took place from July 1, 2012 to March 1, 2013 and included patients who were ≥18 years old and required trauma team activation. Observations included baseline demographics (age, gender, type of injury), vital signs, point-of-care arterial blood gas, lactate, and need for MT. RESULTS:One hundred patients were enrolled over the study period. The average age was 34 years, and 82% were male. Forty patients were acidemic (pH < 7.35), and there was a significant difference in lactate levels between the acidemic and non-acidemic groups (p < 0.002). We found a strong correlation between pH and lactate: rs = -0.38, t = -4.03, p < 0.001. In addition, using a logistic regression, we show that pH was associated with activation of MT (p = 0.002). CONCLUSION/CONCLUSIONS:This is a prospective observational cohort study with level II evidence. This study demonstrates that acidemia was strongly correlated to serum lactate, lactate levels were higher in the acidemic group, and metabolic acidemia was associated with the activation of MT for trauma patients at our institution.

OBJECTIVE:The objectives of this study are to design an artificial neural network (ANN) and to test it retrospectively to determine if it may be used to predict emergency department (ED) volume. METHODS:We conducted a retrospective review of patient registry data from February 4, 2007, to December 31, 2009, from an inner city, tertiary care hospital. We harvested data regarding weather, days of week, air quality, and special events to train the ANN. The ANN belongs to a class of neural networks called multilayer perceptrons. We designed an ANN composed of 37 input neurons, 22 hidden neurons, and 1 output neuron designed to predict the daily number of ED visits. The training method is a supervised backpropagation algorithm that uses mean squared error to minimize the average squared error between the ANN's output and the number of ED visits over all the example pairs. RESULTS:A linear regression between the predicted and actual ED visits demonstrated an R2 of 0.957 with a slope of 0.997. Ninety-five percent of the time, the ANN was within 20 visits. CONCLUSION/CONCLUSIONS:The results of this study show that a properly designed ANN is an effective tool that may be used to predict ED volume. The scatterplot demonstrates that the ANN is least predictive at the extreme ends of the spectrum suggesting that the ANN may be missing important variables. A properly calibrated ANN may have the potential to allow ED administrators to staff their units more appropriately in an effort to reduce patient wait times, decrease ED physician burnout rates, and increase the ability of caregivers to provide quality patient care. A prospective is needed to validate the utility of the ANN.

BACKGROUND:Triage vital signs are often used to help determine a trauma patient's haemodynamic status. Recent studies have demonstrated that these may not be very specific in determining major injury. The purpose of this study was to determine if there is any correlation between triage vital signs, base deficit (BD) and lactate, and to determine the odds of operative intervention in penetrating trauma patients. METHODS:A prospective observational cohort study was undertaken. Baseline vital signs, BD and lactate were recorded in all patients for whom the trauma team was activated. Pearson correlation and coefficient (ρ) were calculated. ORs were calculated. RESULTS:75 patients were enrolled. Pearson correlations and coefficients calculated for lactate to systolic blood pressure were: -0.052 (ρ=0.0011, 95% CI -0.225 to 0.228); lactate and HR: 0.23 (ρ=0.0166, 95% CI -0.211 to 0.242); lactate and RR: 0.23 (ρ=0.054, 95% CI -0.174 to 0.277). BD to systolic blood pressure were: 0.003 (ρ=0.00001, 95% CI -0.229 to 0.224); BD and HR: -0.19 (ρ=0.038, 95% CI -0.399 to 0.038); BD and RR: -0.019 (ρ=0.0004, 95% CI -0.244 to 0.208). Odds of operative intervention were greater in patients with abnormally high lactate, OR 4.17 (95% CI 1.57 to 11), but not for BD, OR 2.53 (95% CI 0.99 to 6.45), or any of the vital signs. CONCLUSIONS:Triage vital signs have no correlation to lactate or BD levels in penetrating trauma patients. Odds of operative intervention are greater in patients with abnormally high serum lactate levels, but not in those with abnormal triage vital signs or BD.