Antifungal Dosing in Critically Ill Patients on Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is an established advanced life support system, providing temporary cardiac and/or respiratory support in critically ill patients. Fungal infections are associated with increased mortality in patients on ECMO. Antifungal drug dosing for critically ill patients is highly challenging because of altered pharmacokinetics (PK). PK changes during critical illness; in particular, the drug volume of distribution (Vd) and clearance can be exacerbated by ECMO. This article discusses the available literature to inform adequate dosing of antifungals in this patient population. The number of antifungal PK studies in critically ill patients on ECMO is growing; currently available literature consists of case reports and studies with small sample sizes providing inconsistent findings, with scant or no data for some antifungals. Current data are insufficient to provide definitive empirical drug dosing guidance and use of dosing strategies derived from critically patients not on ECMO is reasonable. However, due to high PK variability, therapeutic drug monitoring should be considered where available in critically ill patients receiving ECMO to prevent subtherapeutic or toxic antifungal exposures.

Conventional and Novel Approaches to Immunosuppression in Lung Transplantation

Most therapeutic advances in immunosuppression have occurred over the past few decades. Although modern strategies have been effective in reducing acute cellular rejection, excess immunosuppression comes at the price of toxicity, opportunistic infection, and malignancy. As our understanding of the immune system and allograft rejection becomes more nuanced, there is an opportunity to evolve immunosuppression protocols to optimize longer term outcomes while mitigating the deleterious effects of traditional protocols.

Oral milrinone for management of refractory right ventricular failure in patients with left ventricular assist devices

AIMS

We present a single-centre retrospective experience using oral milrinone in patients with a left ventricular assist device (LVAD) and concurrent refractory right ventricular failure.

METHODS AND RESULTS

All patients implanted with LVAD between January 2013 and July 2021 from a high-volume advanced heart failure service were reviewed. Eight patients were initiated on oral milrinone during this period. Oral milrinone was started 1.5 [inter-quartile range (IQR) 1-2.3] years after LVAD implantation and continued for 1.2 (IQR 0.5-2.8) years. Therapeutic milrinone levels were achieved (232.2 ± 153.4 ng/mL) with 62.4 ± 18% of time within the therapeutic range. Two patients had adverse events (non-sustained ventricular tachycardia and ventricular fibrillation effectively treated by internal cardioverter defibrillator) but did not require milrinone discontinuation. Four deaths occurred, one after transplant and three from disease progression determined to be unrelated to oral milrinone use. Three patients continue oral milrinone therapy in the community. There was no significant difference found after the initiation of oral milrinone on any of the physiological measures; however, there were trends in reduction of New York Heart Association class from 3.4 ± 0.5 to 3.0 ± 0.8 (P = 0.08), reduction of right atrial/wedge pressure from 0.9 ± 0.3 to 0.5 ± 0.2 (P = 0.08), and improvement of right ventricular stroke work index from 3.8 ± 2 to 5.8 ± 2.7 (P = 0.16).

CONCLUSIONS

Oral milrinone appears safe for long-term use in the outpatient setting when combined with therapeutic monitoring in this complex medical cohort with limited management options. Further study is needed to ascertain whether this treatment is effective in reducing heart failure symptoms and admissions.

Machines that help machines to help patients: optimising antimicrobial dosing in patients receiving extracorporeal membrane oxygenation and renal replacement therapy using dosing software

Intensive care unit (ICU) patients with end-organ failure will require specialised machines or extracorporeal therapies to support the failing organs that would otherwise lead to death. ICU patients with severe acute kidney injury may require renal replacement therapy (RRT) to remove fluid and wastes from the body, and patients with severe cardiorespiratory failure will require extracorporeal membrane oxygenation (ECMO) to maintain adequate oxygen delivery whilst the underlying pathology is evaluated and managed. The presence of ECMO and RRT machines can further augment the existing pharmacokinetic (PK) alterations during critical illness. Significant changes in the apparent volume of distribution (V_d) and drug clearance (CL) for many important drugs have been reported during ECMO and RRT. Conventional antimicrobial dosing regimens rarely consider the impact of these changes and consequently, are unlikely to achieve effective antimicrobial exposures in critically ill patients receiving ECMO and/or RRT. Therefore, an in-depth understanding on potential PK changes during ECMO and/or RRT is required to inform antimicrobial dosing strategies in patients receiving ECMO and/or RRT. In this narrative review, we aim to discuss the potential impact of ECMO and RRT on the PK of antimicrobials and antimicrobial dosing requirements whilst receiving these extracorporeal therapies. The potential benefits of therapeutic drug monitoring (TDM) and dosing software to facilitate antimicrobial therapy for critically ill patients receiving ECMO and/or RRT are also reviewed and highlighted.

A Large Retrospective Assessment of Voriconazole Exposure in Patients Treated with Extracorporeal Membrane Oxygenation

BACKGROUND

Voriconazole is one of the first-line therapies for invasive pulmonary aspergillosis. Drug concentrations might be significantly influenced by the use of extracorporeal membrane oxygenation (ECMO). We aimed to assess the effect of ECMO on voriconazole exposure in a large patient population.

METHODS

Critically ill patients from eight centers in four countries treated with voriconazole during ECMO support were included in this retrospective study. Voriconazole concentrations were collected in a period on ECMO and before/after ECMO treatment. Multivariate analyses were performed to evaluate the effect of ECMO on voriconazole exposure and to assess the impact of possible saturation of the circuit's binding sites over time.

RESULTS

Sixty-nine patients and 337 samples (190 during and 147 before/after ECMO) were analyzed. Subtherapeutic concentrations (<2 mg/L) were observed in 56% of the samples during ECMO and 39% without ECMO (p = 0.80). The median trough concentration, for a similar daily dose, was 2.4 (1.2-4.7) mg/L under ECMO and 2.5 (1.4-3.9) mg/L without ECMO (p = 0.58). Extensive inter-and intrasubject variability were observed. Neither ECMO nor squared day of ECMO (saturation) were retained as significant covariates on voriconazole exposure.

CONCLUSIONS

No significant ECMO-effect was observed on voriconazole exposure. A large proportion of patients had voriconazole subtherapeutic concentrations.

Challenging immunosuppression treatment in lung transplant recipients with kidney failure

Kidney failure after lung transplantation is a risk factor for chronic kidney disease. Calcineurin inhibitors are immunosuppressants which play a major role in terms of postoperative kidney failure after lung transplantation. We report our preliminary experience with the anti-interleukin-2 monoclonal antibody Basiliximab utilized as a "calcineurin inhibitor-free window" in the setting of early postoperative kidney failure after lung transplantation. Between 2012 and 2015 nine lung transplant patients who developed kidney failure for more than 14 days were included. Basiliximab was administrated in three doses (Day 0, 4, and 20) whilst Tacrolimus was discontinued or reduced to maintain a serum level between 2 and 4 ng/mL. Baseline glomerular filtration rate pre transplant was normal for all patients. Seven patients completely recovered from kidney failure (67%, mean eGFR pre and post Basiliximab: 42.3 mL/min/1.73 m(2) and 69 mL/min/1.73 m(2)) and were switched back on Tacrolimus. Only one of these patients still needs ongoing renal replacement therapy. Two patients showed no recovery from kidney failure and did not survive. Basiliximab might be a safe and feasible therapeutical option in patients which are affected by calcineurin inhibitor-related kidney failure in the early post lung transplant period. Further studies are necessary to confirm our preliminary results.

Usefulness of Rabbit Anti-thymocyte Globulin in Patients With Giant Cell Myocarditis

Giant cell myocarditis (GCM) is an aggressive inflammatory myocardial disease. Immunosuppression is an effective treatment for some cases. However, the duration of action of agents such as muromonab CD3 is short and others such as the calcineurin inhibitors may lead to renal failure. Here we describe the outcome of a novel approach to treatment using rabbit anti-thymocyte globulin (RATG). A retrospective analysis of 6 patients treated with RATG for GCM was performed. Diagnosis was confirmed by endomyocardial biopsy, and RATG was administered with a high dose of corticosteroids. None of the patients had cytokine release syndrome or leukopenia, and 5 had thrombocytopenia (2 of them severe). Only 1 had a serious bleeding event that occurred after implantation of mechanical circulatory support. None developed impaired renal function after the treatment. Five were successfully discharged home with an increase in global left ventricular ejection fraction of 29%. Four are currently alive without recurrent disease, 1 of them after heart transplantation, with a mean follow-up of 970 days (423 to 1,875 days), left ventricular ejection fraction of 53%, and all in current New York Heart Association Classification class ≤II. Only 1 case had GCM recurrence. There were 2 deaths: one because of intracranial bleeding after mechanical circulatory support implantation and the other caused by primary graft dysfunction. In conclusion, patients with GCM can be successfully immunosuppressed with RATG and corticosteroids, thereby avoiding renal impairment. Early thrombocytopenia is the main adverse event. Larger cohorts of patients are necessary to compare the different immunosuppressant strategies available for GCM in a randomized fashion.

Comparison of clinical and economic outcomes of two antibiotic prophylaxis regimens for sternal wound infection in high-risk patients following coronary artery bypass grafting surgery: a prospective randomised double-blind controlled trial

OBJECTIVE

Prospective studies show a 10% incidence of sternal wound infection (SWI) after 90 days of follow-up, compared with infection rates of 5% reported by the National Nosocomial Infections Surveillance System after only 30 days of follow-up. This incidence increases 2-3 times in high-risk patients.

DESIGN

Prospective randomised double-blind controlled clinical trial.

SETTING

Cardiothoracic centre, UK.

PATIENTS

Patients were eligible if they were undergoing median sternotomy for primary isolated coronary artery bypass grafting, with at least one internal thoracic artery used for coronary grafting and having one or more of the following three risk factors: (1) obesity, defined as body mass index 30 kg/m(2); (2) diabetes mellitus; or (3) bilateral internal thoracic artery grafts (ie, the use of the other internal thoracic artery).

INTERVENTIONS

The study group received a single dose of gentamicin 2 mg/kg, rifampicin 600 mg and vancomycin 15 mg/kg, with three further doses of 7.5 mg/kg at 12-hour intervals. The control group received cefuroxime 1.5 g at induction and three further doses of 750 mg at 8-hour intervals.

MAIN OUTCOME MEASURES

The primary end point was the incidence of SWI at 90 days. The secondary end point was the antibiotic and hospital costs.

RESULTS

During the study period, 486 patients underwent isolated coronary artery bypass grafting with a 30-day SWI of 7.6%. 186 high-risk patients were recruited and analysed: 87 in the study group and 99 in the control group. 90-day SWI was significantly reduced in 8 patients in the study group (9.2%; 95% CI 3.5% to 15.3%) compared with 25 patients in the control group (25.2%; 95% CI 19.5% to 39.4%; p = 0.004). The study group had a significantly lower cost of antibiotics (21.2% reduction--US$96/patient; p<0.001), and a significantly lower hospital cost (20.4% reduction in cost--US$3800/patient; p = 0.04).

CONCLUSIONS

Longer and broader-spectrum antibiotic prophylaxis significantly reduces the incidence of SWI in high-risk patients, with a significant economic benefit in costs of antibiotics as well as hospital costs.

Initial experience with sirolimus and mycophenolate mofetil for renal rescue from cyclosporine nephrotoxicity after heart transplantation

Calcineurin inhibitors (CNIs) have become the cornerstone of immunosuppressive regimens following heart transplantation, but their use is associated with nephrotoxicity. We evaluated a CNI elimination protocol in 14 patients with renal impairment at 48.3 +/- 36.0 months after heart transplantation. The mean serum creatinine was 321 +/- 107 micromol/L; cyclosporine (n=13) or tacrolimus (n=1) was discontinued with sirolimus commenced immediately, initially aiming for a target trough level of 16 (12 to 20) ng/mL. If patients were not receiving mycophenolate (MMF) this was initiated at 1 g bid. The transfer period was covered with a tapering course of corticosteroids. In addition to monitoring clinical status, hematology, biochemistry, and sirolimus levels, graft function was assessed by echocardiography, ECG, and, where indicated, endomyocardial biopsy. Renal function improved in 12 patients (with 6 having a greater than 40% decrease in serum creatinine), remained unchanged in 1, and deteriorated in 1. Two patients who were converted at 15 and 139 months after transplantation experienced grade 3A rejection. One patient experienced a fall in ejection fraction without histologic evidence of rejection. Sirolimus was discontinued in three patients because of side effects: bone marrow suppression, presumed lymphocytic pneumonitis, and generalized acneform rash complicated by an axillary abcess; 50% of patients continue on sirolimus. In conclusion, withdrawal of CNIs after heart transplantation resulted in an improvement in renal function in most patients: 43% experienced a substantial improvement. CNI elimination protocols need to be refined to reduce the risk of breakthrough rejection and to minimize side effects while protecting renal function after heart transplantation.

Management of an ABO-incompatible lung transplant

A 24-year-old woman with cystic fibrosis underwent bilateral sequential lung transplantation and unintentionally received an ABO incompatible graft (blood type A(1) graft into a type O recipient). The recipient had a high titer of IgG anti-A antibody (256 by the indirect antiglobulin test). Emergency treatment included antibody removal by plasmapheresis and additional immunosuppression with mycophenolate, rabbit antithymocyte globulin and polyspecific intravenous immunoglobulin. Subsequently, immunoadsorption and the anti-CD20 antibody rituximab were used to remove anti-A antibody and inhibit its resynthesis. Early graft function was good; one episode of rejection at Day 46 responded promptly to treatment with methylprednisolone. Subsequently, graft function continued to improve and anti-A antibody titers remained low. No infectious or other complications were encountered. The treatment regimen that we adopted may prove useful in other cases of unplanned ABO-incompatible organ transplants. The successful outcome suggests that planned ABO-incompatible lung transplants may be possible.