Alexander J. Gregory

Up to 40% of cardiac surgery patients present with preoperative anemia, which is associated with significant risks and management challenges. This review highlights the increased perioperative risk attributable to preoperative anemia as well as recommended optimization strategies. This includes screening for anemia and iron deficiency as well as the appropriate use of intravenous iron replacement, vitamin B12, folic acid, and erythrocyte stimulating agents. The mechanism of action, optimal dosing, and anticipated time to response are also described. The benefits of proactive treatment of preoperative anemia within the context of a comprehensive patient blood management program are also explored. Finally, a discussion is provided on how to overcome common barriers in the treatment of preoperative anemia.

Enhanced Recovery After Surgery (ERAS) is an evidence-based, holistic perioperative recovery protocol intended to improve patient outcomes and decrease postoperative complication rates. While ERAS protocols were first introduced in 1997, specific guidelines for cardiac surgery were not established until 2019. Although the core principles of ERAS remain constant across surgical disciplines, ERAS guidelines for cardiac surgery have remained relatively understudied, likely due to the unique complexities posed by cardiac procedures. Within this comprehensive narrative review, we aimed to explore the current guidelines and evidence for ERAS in both cardiac and non-cardiac surgeries. In non-cardiac surgeries, ERAS has been shown to improve various outcomes, including ICU length of stay, patient satisfaction, and pain management. ERAS for cardiac surgery has also shown encouraging results, including shorter ICU and hospital stays, reduced postoperative opioid use, and faster recovery times. However, there is limited consensus across studies, particularly regarding its impact on morbidity and mortality, with mixed results reported. Furthermore, the limited data on the efficacy of ERAS in minimally invasive cardiac surgeries makes it difficult to establish well-supported guidelines for these procedures. Despite its limitations, the overall outcomes of ERAS for cardiac surgery remain promising. As our understanding and application of ERAS in cardiac surgery continue to evolve, these protocols have the potential to redefine cardiac surgical care standards.

Enhancing recovery protocols seek to optimize multiple aspects of care throughout the patient’s perioperative cardiac surgery journey. Fast-track recovery protocols, specifically those involving earlier extubation, have been among the early methods to enhance a patient’s recovery. However, how early these protocols should be implemented after surgery remains a source of ongoing controversy. Strong opinions exist on whether it is appropriate to extubate patients after cardiac surgery in the operating room (OR). Although OR extubation may offer benefits such as reduced intensive care unit length of stay and resource utilization, there are concerns regarding safety, patient selection, and inconsistent outcomes, which have raised significant controversy. This review aims to discuss the reasons why a team may consider exploring extubation in the OR and provide a practical approach for the interdisciplinary team seeking to implement this practice in appropriately selected patients.

We thank the authors for their thoughtful letter and informative review regarding the effects of anesthesia on the cardiovascular system.1 This previous work using animal models has been foundational in framing our understanding of arterial physiology and the effects of anesthetic agents. Our omission of these previous works in our recently published review on aortic biomechanics was not meant to diminish their importance.2 Rather, the purpose of our review was to focus on concepts related to the material properties of the aorta itself in health, disease, surgery, and anesthesia, and to propose that local aortic changes may have both physiologic and clinical ramifications through the aorta’s relationship with the heart and distal arteries.Certainly, the previous studies highlighted by Dr. Pagel et al., using a three-element Windkessel model in animals, have provided important details on the effects of anesthesia on aortic biomechanics. But we respectfully submit that it may not tell the whole story. First, compliance, as calculated in the Windkessel model, is total arterial compliance, not exclusively aortic.3 The contribution of small arteries to compliance is considerable and, in humans, increases with age-related aortic stiffening, thereby “blurring the distinction between large and small artery function.”4 As such, the described changes to compliance from the Windkessel model likely cannot be attributed to the aortic biomechanical properties alone. Second, we disagree with the contention that characteristic aortic impedance is “the resistance of the aorta itself.” Although aortic impedance has the units of resistance, it exists only with pulsatile flow and pressure and is a function of the modulus of elasticity and radius.3 Similar to compliance, there is no exact anatomical aortic correlate to aortic impedance, although it characterizes the vessel in close proximity to the measurement. Therefore, although we agree that left ventricular afterload can be modeled using the Windkessel, we believe that aortic biomechanics as defined by the authors is only partly responsible.Aortic biomechanics, at the level of local aortic microstructure and mechanical behavior, has until now been limited to bench-top testing on excised tissue. With recent advancements in imaging technology, there are new opportunities to explore the aorta in vivo and hopefully gain new insights into local aortic biomechanical properties in the clinical anesthesia environment. As we assert in our review, this work has yet to be done.Our understanding of cardiovascular physiology has greatly benefitted from the previous scientific work of Dr. Pagel and others who have published using similar arterial system models. They have put together much of the puzzle as it pertains to anesthesia and cardiovascular physiology. We believe that the additional perspectives on aortic biomechanics described in our review hold potential to add a piece to said puzzle, not replace it altogether.The authors declare no competing interests.