The International Journal of Artificial Organs, 2022
The use of acute mechanical circulatory support (MCS) has increased over the last decade. For pat... more The use of acute mechanical circulatory support (MCS) has increased over the last decade. For patients with left-ventricular failure, an Impella® (Abiomed, Danvers, MA) may be used to improve cardiac output. The purpose of this study is to describe Impella® anticoagulation patterns and evaluate the safety and effectiveness of our protocol. This is a retrospective review of all adult patients who required at least 24 h of Impella® support and received a heparin-based purge solution. In total, 109 patients were included in the final analysis. The most common indication for Impella® device insertion was cardiogenic shock (76%) with the remaining patients receiving a device for a high-risk procedures; typically coronary artery bypass grafting or percutaneous coronary intervention. A total of 9 thrombotic events occurred among 8 (7%) patients and 50 bleeding events occurred among 43 (39%) patients, with the most common classification being BARC 3a (60%). A univariate analysis revealed th...
A celebrated theorem of Buchweitz, Greuel, Knörrer, and Schreyer is that the hypersurface singula... more A celebrated theorem of Buchweitz, Greuel, Knörrer, and Schreyer is that the hypersurface singularities of finite representation type, i.e. the hypersurface singularities admitting only finitely many indecomposable maximal Cohen-Macaulay modules, are exactly the ADE singularities. The codimension 2 singularities that are the analogs of the ADE singularities have been classified by Frühbis-Krühger and Neumer, and it is natural to expect an analogous result holds for these singularities. In this paper, I will present a proof that, in contrast to hypersurfaces, Frühbis-Krühger and Neumer’s singularities include a subset of singularities of infinite representation type.
The Journal of Heart and Lung Transplantation, 2021
Purpose Clostridium difficile infection (CDI) is associated with increased morbidity and mortalit... more Purpose Clostridium difficile infection (CDI) is associated with increased morbidity and mortality after thoracic transplant. In response to a series of cases, our institution implemented primary CDI prophylaxis with oral vancomycin 125 mg twice daily. Methods We retrospectively reviewed all thoracic transplant recipients from January 2018 to March 2020. Exclusion criteria included postoperative antibiotics Results In total, we reviewed 164 thoracic transplant recipients. We excluded 55 patients for a final cohort of 109 patients. There were 63 lung and 46 heart transplant recipients. Twenty-two patients (20%) received prophylaxis and 87 patients (80%) did not. Baseline demographics and hospitalization or receipt of antibiotics within prior 90 days did not differ between groups. Median length of stay was 30 and 43 days in the No PPX and OVP groups, respectively (p=0.01). Post-transplant, more patients in the OVP group were mechanically ventilated greater than 72 hours (16% vs. 46%, p=0.003) or on ECMO (7% vs. 27%, p=0.006). Median duration of antibiotics was 18 and 28 days in the No PPX and OVP groups, respectively (p=0.002). OVP overlapped a median of 95% of antibiotic days and continued for a median of 4 days after antibiotic discontinuation. During hospitalization, CDI occurred in 6 patients (7%) in the No PPX arm and 0 patients in the OVP arm (p=0.35). CDI-free survival did not differ between groups based on the Kaplan-Meier survival analysis (p=0.16). Conclusion Despite a higher degree of post-transplant organ support and significantly longer duration of antibiotics and length of stay, the incidence of CDI trended lower with the use of OVP. Primary OVP should be investigated in larger cohorts.
Tacrolimus is a mainstay medication for graft-versus-host disease (GVHD) prophylaxis in combinati... more Tacrolimus is a mainstay medication for graft-versus-host disease (GVHD) prophylaxis in combination with other immunosuppressive agents. Achieving therapeutic tacrolimus levels is vital in preventing acute GVHD (aGVHD), while supratherapeutic levels may increase risk of toxicity and relapse. We performed a single center retrospective chart review including all adult patients post-allogeneic hematopoietic stem-cell transplantation who received initial tacrolimus continuous intravenous infusion for GVHD prophylaxis between June 1, 2017 and December 31, 2019. The primary outcome was the percent of patients with an initial therapeutic tacrolimus level, defined as 5–12 ng/mL, after empiric weight-based dosing at 0.02 mg/kg/day. Secondary outcomes included evidence of tacrolimus toxicity within seven days of initiation, incidence of aGVHD by day 100, and relapse after six months. An initial therapeutic level was achieved in 47% of patients with a median initial level of 12.4 ng/mL. Fifty-...
ABSTRACTAccurate assignment of age class is critical for understanding most demographic processes... more ABSTRACTAccurate assignment of age class is critical for understanding most demographic processes. For waterfowl, most techniques for determining age class require birds in hand, reducing utility for quickly and efficiently sampling a large portion of the population. As an alternative, we sought to establish an observation‐based methodology, achievable in the field with standard optics, for determining age class of Barrow's goldeneyes (Bucephala islandica). We photographed heads, wings, and bellies of 232 Barrow's goldeneyes captured during late winter (February–April) of 2007–2015 along the north Pacific Coast. From these photographs, we focused on 5 external characteristics for both males and females, with binary states that putatively corresponded to 2 age classes—first‐year birds (<1 yr) and adults (>1 yr). For males, all 5 external traits (belly color, head color, eye color, facial crescent, median secondary coverts color) had binary states that were reliably dist...
We conducted a retrospective review of thoracic transplant recipients (22 heart and 16 lung trans... more We conducted a retrospective review of thoracic transplant recipients (22 heart and 16 lung transplant recipients) prospectively enrolled in a single‐center observational study of HCV NAT+ organ transplantation in HCV NAT− recipients. All recipients were treated with 8 weeks of glecaprevir‐pibrentasvir (GP) for HCV viremia in addition to standard triple immunosuppression post‐transplant. Thoracic transplant recipients of HCV NAT− organs were used as a control (24 heart and 22 lung transplant recipients). Our primary outcome was to assess the effect of GP on tacrolimus dose requirements. Secondary objectives included assessing drug interactions with common post‐transplant medications, adverse effects, and the need to hold or discontinue GP therapy. The median tacrolimus concentration‐to‐dose ratio (CDR) in the cohort was 184 (99‐260) during GP therapy and 154 (78‐304) over the first month after GP (P = .79). Trends in median tacrolimus CDR were similar on a per‐week basis and per‐pat...
BackgroundThe use of direct‐acting antivirals (DAA) has expanded transplantation from hepatitis C... more BackgroundThe use of direct‐acting antivirals (DAA) has expanded transplantation from hepatitis C viremic donors (HCV‐VIR). Our team has conducted an open‐label, prospective trial to assess outcomes transplanting HCV viremic hearts. Glecaprevir/pibrentasvir (GLE/PIB) was our sole DAA.MethodsSerial quantitative hepatitis C virus (HCV) RNA PCR was obtained to assess HCV viral titers. Between January 2018 and June 2019, a total of 50 recipients were transplanted. Of these, 22/50 (44%) were from HCV‐VIR, the remaining 28 from non‐viremic (HCV NON‐VIR) donors. An 8‐week course of GLE/PIB was initiated at 1 week post‐transplant.ResultsThere was no difference in demographic or clinical parameters between groups. All 22 recipients of HCV‐VIR transplants became viremic. GLE/PIB was effective in decreasing viremia to undetectable levels by 6 weeks post‐transplant in all patients. The median time to first undetectable HCV quantitative PCR was (4.3 weeks, IQR: 4‐5.7 weeks). All patients demonst...
Seminars in Thoracic and Cardiovascular Surgery, 2020
Thoracic organs from Hepatitis C virus (HCV) positive donors are not commonly used for transplant... more Thoracic organs from Hepatitis C virus (HCV) positive donors are not commonly used for transplantation. The development of direct-acting antivirals (DAA) for HCV treatment has led to renewed interest in using HCV-positive organs. We evaluated HCV transmission rates, viremia clearance, and short-term outcomes in HCV-negative patients who received HCV-positive thoracic organs at our institution. From January 1, 2018 to May 31, 2019, 38 patients underwent HCV-positive thoracic organ transplantation (16 lungs and 22 hearts). Heart recipients were started on glecaprevir/pibrentasvir, a pangenotypic DAA, when they developed HCV viremia. Lung recipients were empirically started on glecaprevir/pibrentasvir within the first three post-transplant days. The primary outcome was cure of HCV defined as sustained virologic response at 12 weeks (SVR12). All heart recipients developed HCV viremia with median initial viral load of 64,565 IU/mL (interquartile range: 1660 to 473,151). The median time from DAA initiation to viremia clearance was 19 days (confidence interval: 15-27 days). 11 out of 16 (68.8%) lung recipients developed HCV viremia with median initial viral load of 26 IU/mL (interquartile range: 15 to 143). The median time from DAA initiation to viremia clearance was 10 days (confidence interval: 6-17 days). 5 out of 16 (31.3%) lung recipients never became viremic. All patients demonstrated SVR12. Thoracic organ transplantation from HCV viremic donors is safe with excellent short-term survival. Early initiation of HCV treatment results in rapid viremia clearance and SVR12. Long-term outcomes and optimal timing of DAA initiation remains to be determined.
Postoperative antibiotics (PA) are often administered to patients after instrumented spinal surge... more Postoperative antibiotics (PA) are often administered to patients after instrumented spinal surgery until all drains are removed to prevent surgical site infections (SSI). This practice is discouraged by numerous medical society guidelines, so our institutional Neurosurgery Quality Improvement Committee decided to discontinue use of PA for this population. We retrospectively reviewed data for patients who had instrumented spinal surgery at our institution for seven months before and after this policy change and compared the frequency of SSI and development of antibiotic related complications in patients who received PA to those who did not (non-PA). We identified 188 PA patients and 158 non-PA patients. Discontinuation of PA did not result in an increase in frequency of SSI (2% of PA patients vs. 0.6% of non-PA patients, p = .4). Growth of resistant bacteria was not significantly reduced in the non-PA period in comparison to the PA period (2% in the PA period and 1% in the non-PA pe...
Purpose: Leveraging pharmacy personnel resources for the purpose of antimicrobial stewardship pro... more Purpose: Leveraging pharmacy personnel resources for the purpose of antimicrobial stewardship program (ASP) operations presents a challenging task. We describe our experience integrating all pharmacists into an ASP, and evaluate the impact on ASP interventions, antimicrobial utilization, rate of selected hospital-onset infections and readmission. Summary: During a study period (January 1 to December 31, 2015), a total of 14 552 ASP-related pharmacy interventions were performed (ASP clinical pharmacotherapy specialists [CPS] n = 4025; non-ASP CPS n = 4888; hospital pharmacists n = 5639). Sixty percent of interventions by ASP CPS were initiated utilizing the dedicated ASP phone, and 40% through prospective audit and feedback. Non-ASP CPS performed interventions during bedside rounds (dose adjustment 23%, initiate new or alternative anti-infective 21%, discontinue antibiotic(s) 12%, therapeutic drug monitoring 11%, de-escalation 4%), whereas hospital pharmacists participated at the poi...
Vasopressors are an integral component of the management of septic shock and are traditionally gi... more Vasopressors are an integral component of the management of septic shock and are traditionally given via a central venous catheter (CVC) due to the risk of tissue injury and necrosis if extravasated. However, the need for a CVC for the management of septic shock has been questioned, and the risk of extravasation and incidence of severe injury when vasopressors are given via a peripheral venous line (PVL) remains poorly defined. We performed a retrospective chart review of 202 patients who received vasopressors through a PVL. The objective was to describe the vasopressors administered peripherally, PVL size and location, the incidence of extravasation events, and the management of extravasation events. The primary vasopressors used were norepinephrine and phenylephrine. The most common PVL sites used were the forearm and antecubital fossa. The incidence of extravasation was 4%. All of the events were managed conservatively; none required an antidote or surgical management. Vasopresso...
The International Journal of Artificial Organs, 2022
The use of acute mechanical circulatory support (MCS) has increased over the last decade. For pat... more The use of acute mechanical circulatory support (MCS) has increased over the last decade. For patients with left-ventricular failure, an Impella® (Abiomed, Danvers, MA) may be used to improve cardiac output. The purpose of this study is to describe Impella® anticoagulation patterns and evaluate the safety and effectiveness of our protocol. This is a retrospective review of all adult patients who required at least 24 h of Impella® support and received a heparin-based purge solution. In total, 109 patients were included in the final analysis. The most common indication for Impella® device insertion was cardiogenic shock (76%) with the remaining patients receiving a device for a high-risk procedures; typically coronary artery bypass grafting or percutaneous coronary intervention. A total of 9 thrombotic events occurred among 8 (7%) patients and 50 bleeding events occurred among 43 (39%) patients, with the most common classification being BARC 3a (60%). A univariate analysis revealed th...
A celebrated theorem of Buchweitz, Greuel, Knörrer, and Schreyer is that the hypersurface singula... more A celebrated theorem of Buchweitz, Greuel, Knörrer, and Schreyer is that the hypersurface singularities of finite representation type, i.e. the hypersurface singularities admitting only finitely many indecomposable maximal Cohen-Macaulay modules, are exactly the ADE singularities. The codimension 2 singularities that are the analogs of the ADE singularities have been classified by Frühbis-Krühger and Neumer, and it is natural to expect an analogous result holds for these singularities. In this paper, I will present a proof that, in contrast to hypersurfaces, Frühbis-Krühger and Neumer’s singularities include a subset of singularities of infinite representation type.
The Journal of Heart and Lung Transplantation, 2021
Purpose Clostridium difficile infection (CDI) is associated with increased morbidity and mortalit... more Purpose Clostridium difficile infection (CDI) is associated with increased morbidity and mortality after thoracic transplant. In response to a series of cases, our institution implemented primary CDI prophylaxis with oral vancomycin 125 mg twice daily. Methods We retrospectively reviewed all thoracic transplant recipients from January 2018 to March 2020. Exclusion criteria included postoperative antibiotics Results In total, we reviewed 164 thoracic transplant recipients. We excluded 55 patients for a final cohort of 109 patients. There were 63 lung and 46 heart transplant recipients. Twenty-two patients (20%) received prophylaxis and 87 patients (80%) did not. Baseline demographics and hospitalization or receipt of antibiotics within prior 90 days did not differ between groups. Median length of stay was 30 and 43 days in the No PPX and OVP groups, respectively (p=0.01). Post-transplant, more patients in the OVP group were mechanically ventilated greater than 72 hours (16% vs. 46%, p=0.003) or on ECMO (7% vs. 27%, p=0.006). Median duration of antibiotics was 18 and 28 days in the No PPX and OVP groups, respectively (p=0.002). OVP overlapped a median of 95% of antibiotic days and continued for a median of 4 days after antibiotic discontinuation. During hospitalization, CDI occurred in 6 patients (7%) in the No PPX arm and 0 patients in the OVP arm (p=0.35). CDI-free survival did not differ between groups based on the Kaplan-Meier survival analysis (p=0.16). Conclusion Despite a higher degree of post-transplant organ support and significantly longer duration of antibiotics and length of stay, the incidence of CDI trended lower with the use of OVP. Primary OVP should be investigated in larger cohorts.
Tacrolimus is a mainstay medication for graft-versus-host disease (GVHD) prophylaxis in combinati... more Tacrolimus is a mainstay medication for graft-versus-host disease (GVHD) prophylaxis in combination with other immunosuppressive agents. Achieving therapeutic tacrolimus levels is vital in preventing acute GVHD (aGVHD), while supratherapeutic levels may increase risk of toxicity and relapse. We performed a single center retrospective chart review including all adult patients post-allogeneic hematopoietic stem-cell transplantation who received initial tacrolimus continuous intravenous infusion for GVHD prophylaxis between June 1, 2017 and December 31, 2019. The primary outcome was the percent of patients with an initial therapeutic tacrolimus level, defined as 5–12 ng/mL, after empiric weight-based dosing at 0.02 mg/kg/day. Secondary outcomes included evidence of tacrolimus toxicity within seven days of initiation, incidence of aGVHD by day 100, and relapse after six months. An initial therapeutic level was achieved in 47% of patients with a median initial level of 12.4 ng/mL. Fifty-...
ABSTRACTAccurate assignment of age class is critical for understanding most demographic processes... more ABSTRACTAccurate assignment of age class is critical for understanding most demographic processes. For waterfowl, most techniques for determining age class require birds in hand, reducing utility for quickly and efficiently sampling a large portion of the population. As an alternative, we sought to establish an observation‐based methodology, achievable in the field with standard optics, for determining age class of Barrow's goldeneyes (Bucephala islandica). We photographed heads, wings, and bellies of 232 Barrow's goldeneyes captured during late winter (February–April) of 2007–2015 along the north Pacific Coast. From these photographs, we focused on 5 external characteristics for both males and females, with binary states that putatively corresponded to 2 age classes—first‐year birds (<1 yr) and adults (>1 yr). For males, all 5 external traits (belly color, head color, eye color, facial crescent, median secondary coverts color) had binary states that were reliably dist...
We conducted a retrospective review of thoracic transplant recipients (22 heart and 16 lung trans... more We conducted a retrospective review of thoracic transplant recipients (22 heart and 16 lung transplant recipients) prospectively enrolled in a single‐center observational study of HCV NAT+ organ transplantation in HCV NAT− recipients. All recipients were treated with 8 weeks of glecaprevir‐pibrentasvir (GP) for HCV viremia in addition to standard triple immunosuppression post‐transplant. Thoracic transplant recipients of HCV NAT− organs were used as a control (24 heart and 22 lung transplant recipients). Our primary outcome was to assess the effect of GP on tacrolimus dose requirements. Secondary objectives included assessing drug interactions with common post‐transplant medications, adverse effects, and the need to hold or discontinue GP therapy. The median tacrolimus concentration‐to‐dose ratio (CDR) in the cohort was 184 (99‐260) during GP therapy and 154 (78‐304) over the first month after GP (P = .79). Trends in median tacrolimus CDR were similar on a per‐week basis and per‐pat...
BackgroundThe use of direct‐acting antivirals (DAA) has expanded transplantation from hepatitis C... more BackgroundThe use of direct‐acting antivirals (DAA) has expanded transplantation from hepatitis C viremic donors (HCV‐VIR). Our team has conducted an open‐label, prospective trial to assess outcomes transplanting HCV viremic hearts. Glecaprevir/pibrentasvir (GLE/PIB) was our sole DAA.MethodsSerial quantitative hepatitis C virus (HCV) RNA PCR was obtained to assess HCV viral titers. Between January 2018 and June 2019, a total of 50 recipients were transplanted. Of these, 22/50 (44%) were from HCV‐VIR, the remaining 28 from non‐viremic (HCV NON‐VIR) donors. An 8‐week course of GLE/PIB was initiated at 1 week post‐transplant.ResultsThere was no difference in demographic or clinical parameters between groups. All 22 recipients of HCV‐VIR transplants became viremic. GLE/PIB was effective in decreasing viremia to undetectable levels by 6 weeks post‐transplant in all patients. The median time to first undetectable HCV quantitative PCR was (4.3 weeks, IQR: 4‐5.7 weeks). All patients demonst...
Seminars in Thoracic and Cardiovascular Surgery, 2020
Thoracic organs from Hepatitis C virus (HCV) positive donors are not commonly used for transplant... more Thoracic organs from Hepatitis C virus (HCV) positive donors are not commonly used for transplantation. The development of direct-acting antivirals (DAA) for HCV treatment has led to renewed interest in using HCV-positive organs. We evaluated HCV transmission rates, viremia clearance, and short-term outcomes in HCV-negative patients who received HCV-positive thoracic organs at our institution. From January 1, 2018 to May 31, 2019, 38 patients underwent HCV-positive thoracic organ transplantation (16 lungs and 22 hearts). Heart recipients were started on glecaprevir/pibrentasvir, a pangenotypic DAA, when they developed HCV viremia. Lung recipients were empirically started on glecaprevir/pibrentasvir within the first three post-transplant days. The primary outcome was cure of HCV defined as sustained virologic response at 12 weeks (SVR12). All heart recipients developed HCV viremia with median initial viral load of 64,565 IU/mL (interquartile range: 1660 to 473,151). The median time from DAA initiation to viremia clearance was 19 days (confidence interval: 15-27 days). 11 out of 16 (68.8%) lung recipients developed HCV viremia with median initial viral load of 26 IU/mL (interquartile range: 15 to 143). The median time from DAA initiation to viremia clearance was 10 days (confidence interval: 6-17 days). 5 out of 16 (31.3%) lung recipients never became viremic. All patients demonstrated SVR12. Thoracic organ transplantation from HCV viremic donors is safe with excellent short-term survival. Early initiation of HCV treatment results in rapid viremia clearance and SVR12. Long-term outcomes and optimal timing of DAA initiation remains to be determined.
Postoperative antibiotics (PA) are often administered to patients after instrumented spinal surge... more Postoperative antibiotics (PA) are often administered to patients after instrumented spinal surgery until all drains are removed to prevent surgical site infections (SSI). This practice is discouraged by numerous medical society guidelines, so our institutional Neurosurgery Quality Improvement Committee decided to discontinue use of PA for this population. We retrospectively reviewed data for patients who had instrumented spinal surgery at our institution for seven months before and after this policy change and compared the frequency of SSI and development of antibiotic related complications in patients who received PA to those who did not (non-PA). We identified 188 PA patients and 158 non-PA patients. Discontinuation of PA did not result in an increase in frequency of SSI (2% of PA patients vs. 0.6% of non-PA patients, p = .4). Growth of resistant bacteria was not significantly reduced in the non-PA period in comparison to the PA period (2% in the PA period and 1% in the non-PA pe...
Purpose: Leveraging pharmacy personnel resources for the purpose of antimicrobial stewardship pro... more Purpose: Leveraging pharmacy personnel resources for the purpose of antimicrobial stewardship program (ASP) operations presents a challenging task. We describe our experience integrating all pharmacists into an ASP, and evaluate the impact on ASP interventions, antimicrobial utilization, rate of selected hospital-onset infections and readmission. Summary: During a study period (January 1 to December 31, 2015), a total of 14 552 ASP-related pharmacy interventions were performed (ASP clinical pharmacotherapy specialists [CPS] n = 4025; non-ASP CPS n = 4888; hospital pharmacists n = 5639). Sixty percent of interventions by ASP CPS were initiated utilizing the dedicated ASP phone, and 40% through prospective audit and feedback. Non-ASP CPS performed interventions during bedside rounds (dose adjustment 23%, initiate new or alternative anti-infective 21%, discontinue antibiotic(s) 12%, therapeutic drug monitoring 11%, de-escalation 4%), whereas hospital pharmacists participated at the poi...
Vasopressors are an integral component of the management of septic shock and are traditionally gi... more Vasopressors are an integral component of the management of septic shock and are traditionally given via a central venous catheter (CVC) due to the risk of tissue injury and necrosis if extravasated. However, the need for a CVC for the management of septic shock has been questioned, and the risk of extravasation and incidence of severe injury when vasopressors are given via a peripheral venous line (PVL) remains poorly defined. We performed a retrospective chart review of 202 patients who received vasopressors through a PVL. The objective was to describe the vasopressors administered peripherally, PVL size and location, the incidence of extravasation events, and the management of extravasation events. The primary vasopressors used were norepinephrine and phenylephrine. The most common PVL sites used were the forearm and antecubital fossa. The incidence of extravasation was 4%. All of the events were managed conservatively; none required an antidote or surgical management. Vasopresso...
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Papers by Tyler Lewis