Significance: Cytotoxic CD8 T-cell responses against mismatched MHC class I alloantigen are the principal arm of the cellular response against a transplanted organ. How CD4 T cells deliver essential help for development of these cytotoxic responses remains unclear. Here we show that recipient dendritic cells present acquired MHC alloantigen both as intact protein, for recognition by cytotoxic CD8 T cells, and as processed allopeptide, for recognition by helper CD4 T cells. Our findings suggest a mechanism by which help is provided for generating effector cytotoxic CD8 T-cell alloresponses at late time points after transplantation and solve a long-standing conundrum as to why host lymphoid tissue is required for CD8 T-cell allorecognition of graft parenchymal cells.

There has been a significant increase in the utilisation of mechanical circulatory support (MCS) devices for the management of cardiogenic shock over recent years, with new devices being developed and introduced with the aim of improving outcomes for this group of patients. MCS devices may be used as a bridge to recovery or transplantation or intended as a destination therapy. Although these devices are not without their complications, good outcomes are achieved, but not without risk of significant complications. In this article, the complications of MCS devices have been reviewed, including the intra-aortic balloon pump (IABP), Impella, TandemHeart, extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VAD)—temporary and durable.

Despite the ubiquitous use of cardioplegia in cardiac surgery, there is a lack of agreement on various aspects of cardioplegia practice. To discover current cardioplegia practices throughout the world, we undertook a global survey to document contemporary cardiopulmonary bypass practices. A 16-question, Internet-based survey was distributed by regional specialist societies, targeting adult cardiac anesthesiologists. Ten questions concerned caseload and cardioplegia practices, the remaining questions examined anticoagulation and pump-priming practices. The survey was available in English, Spanish, and Portuguese. The survey was launched in June 2015 and remained open until May 2016. A total of 923 responses were analyzed, summarizing practice in Europe (269), North America (334), South America (215), and Australia/New Zealand (105). Inter-regional responses differed for all questions asked (p< .001). In all regions other than South America, blood cardioplegia was the common arrest technique used. The most commonly used cardioplegia solutions were: St. Thomas, Bretschneider, and University of Wisconsin with significant regional variation. The use of additives (most commonly glucose, glutamate, tris-hydroxymethyl aminomethane, and aspartate) varied significantly. This survey has revealed significant variation in international practice with regards to myocardial protection, and is a reminder that there is no clear consensus on the use of cardioplegia. It is unclear why regional practice groups made the choices they have and the clinical impact remains unclear.

Incentive spirometry is frequently used after thoracic surgery as an adjunct to physiotherapy. Despite its widespread use, it has remained challenging to demonstrate a clinical benefit in terms of either incidence of postoperative pulmonary complications or hospital stay. In this literature review, we have observed that, although there is no study supporting clinical benefit in the thoracic surgical patient population generally, there is now emerging evidence of benefit in higher-risk patient populations such as those with COPD. There is an indication that incentive spirometry can lead to a reduction in the incidence of postoperative pulmonary complications in these patients. The problem with studies published to date is that there are many limitations, not least of which is the challenge of achieving patient adherence with performing incentive spirometry as prescribed. Despite the lack of evidence, there remains an appetite for persevering with incentive spirometry in the postoperative thoracic surgical patient because it is a relatively inexpensive intervention that motivates many patients to perform regular breathing exercises long after the therapist has moved on to the next patient.

Pneumomediastinum is a rare clinical finding, but one which can be the source of significant concern for clinicians. By presenting 3 such cases, we highlight that pneumomediastinum can complicate the course of a severe coronavirus disease 2019 infection but emphasize that conservative management is the first-line method of treatment, with gradual resorption of the air from the tissues. It is important to be alert to the development of pneumothorax, which will require drainage.