Procalcitonin Kinetics After Heart Transplantation and as a Marker of Infection in Early Postoperative Course

Procalcitonin for the diagnosis of postoperative bacterial infection after adult cardiac surgery: a systematic review and meta-analysis

BACKGROUND AND AIMS

Patients undergoing cardiac surgery are subject to infectious complications that adversely affect outcomes. Rapid identification is essential for adequate treatment. Procalcitonin (PCT) is a noninvasive blood test that could serve this purpose, however its validity in the cardiac surgery population is still debated. We therefore performed a systematic review and meta-analysis to estimate the accuracy of PCT for the diagnosis of postoperative bacterial infection after cardiac surgery.

METHODS

We included studies on adult cardiac surgery patients, providing estimates of test accuracy. Search was performed on PubMed, EmBase and WebOfScience on April 12th, 2023 and rerun on September 15th, 2023, limited to the last 10 years. Study quality was assessed with the QUADAS-2 tool. The pooled measures of performance and diagnostic accuracy, and corresponding 95% Confidence Intervals (CI), were calculated using a bivariate regression model. Due to the variation in reported thresholds, we used a multiple-thresholds within a study random effects model for meta-analysis (diagmeta R-package).

RESULTS

Eleven studies were included in the systematic review, and 10 (2984 patients) in the meta-analysis. All studies were single-center with observational design, five of which with retrospective data collection. Quality assessment highlighted various issues, mainly concerning lack of prespecified thresholds for the index test in all studies. Results of bivariate model analysis using multiple thresholds within a study identified the optimal threshold at 3 ng/mL, with a mean sensitivity of 0.67 (0.47-0.82), mean specificity of 0.73 (95% CI 0.65-0.79), and AUC of 0.75 (IC95% 0.29-0.95). Given its importance for practice, we also evaluated PCT's predictive capability. We found that positive predictive value is at most close to 50%, also with a high prevalence (30%), and the negative predictive value was always > 90% when prevalence was < 20%.

CONCLUSIONS

These results suggest that PCT may be used to help rule out infection after cardiac surgery. The optimal threshold of 3 ng/mL identified in this work should be confirmed with large, well-designed randomized trials that evaluate the test's impact on health outcomes and on the use of antibiotic therapy. PROSPERO Registration number CRD42023415773. Registered 22 April 2023.

Shorter antibiotic courses in the immunocompromised: the impossible dream?

BACKGROUND

A growing number of studies have demonstrated similar outcomes with shorter courses of antibiotics for bacterial infections. Immunocompromised patients are frequently excluded from these studies despite anticipated benefits associated with shortening antibiotic courses (including lower risks of antibiotic toxicity, Clostridioides difficile infection, drug-resistant pathogens, and microbiome alterations).

OBJECTIVES

To critically review the literature that assesses shorter antibiotic courses in immunocompromised patients, specifically among solid organ transplant recipients and neutropenic fever (NF) syndromes among patients on antineoplastic chemotherapy and undergoing haematopoietic cell transplant.

SOURCES

References were identified through searches of PubMed, Embase, MEDLINE, and clinical guidelines documents.

CONTENT

Among organ transplant recipients, the majority of studies assessing outcomes associated with shorter antibiotic courses have been retrospective but have demonstrated similar rates of clinically relevant endpoints. Patients with high- and low-risk NF have been well-studied, including enrolment in randomized studies, albeit with heterogeneous patient populations and outcomes assessed. Clinical improvement-guided adoption of shorter courses has been associated with fewer antibiotic days and similar rates of fever recurrence and mortality.

IMPLICATIONS

Similar to studies demonstrating efficacy in immunocompetent patients, shorter antibiotic courses should be considered for immunocompromised hosts with presumed bacterial infections. Organ recipients and patients with NF syndromes should be prioritized for study in randomized controlled clinical trials assessing shorter course therapy.

Usefulness of lung ultrasound for early detection of hospital-acquired pneumonia in cardiac critically ill patients on venoarterial extracorporeal membrane oxygenation

Background

Hospital-acquired pneumonia (HAP) is the most common and severe complication in patients treated with venoarterial extracorporeal membrane oxygenation (VA ECMO) and its diagnosis remains challenging. Nothing is known about the usefulness of lung ultrasound (LUS) in early detection of HAP in patients treated with VA ECMO. Also, LUS and chest radiography were performed when HAP was suspected in cardiac critically ill adult VA ECMO presenting with acute respiratory failure. The sonographic features of HAP in VA ECMO patients were determined and we assessed the performance of the lung ultrasound simplified clinical pulmonary score (LUS-sCPIS), the sCPIS and bioclinical parameters or chest radiography alone for early diagnosis of HAP.

Results

We included 70 patients, of which 44 (63%) were independently diagnosed with HAP. LUS examination revealed that color Doppler intrapulmonary flow (P = 0.0000043) and dynamic air bronchogram (P = 0.00024) were the most frequent HAP-related signs. The LUS-sCPIS (area under the curve = 0.77) yielded significantly better results than the sCPIS (area under the curve = 0.65; P = 0.004), while leukocyte count, temperature and chest radiography were not discriminating for HAP diagnosis.

Discussion

Diagnosis of HAP is a daily challenge for the clinician managing patients on venoarterial ECMO. Lung ultrasound can be a valuable tool as the initial imaging modality for the diagnosis of pneumonia. Color Doppler intrapulmonary flow and dynamic air bronchogram appear to be particularly insightful for the diagnosis of HAP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01013-9.