Case report: Blood pressure variation during cardiopulmonary bypass in a patient with multiple sclerosis

Introduction and importance

Multiple sclerosis is known to be associated with both sympathetic and parasympathetic cardiovascular autonomic dysregulation. Thus, patients with multiple sclerosis comorbidity represent a potentially challenging patient population in cardiac surgery, especially in on-pump operations. Despite this, very little is known about the hemodynamics during cardiopulmonary bypass and the optimal perfusion strategy for patients with multiple sclerosis undergoing cardiac operations.

Case presentation

In this report, the authors describe a patient with relapsing-remitting multiple sclerosis, who underwent successful triple valve operation for aortic and mitral stenosis and tricuspid valve insufficiency. Distinct blood pressure variations in form of temporary pressure dips were noted during total cardiopulmonary bypass time as well as during the reperfusion period.

Clinical discussion

Pressure variations were not attributable to surgical, pharmacological or perfusion-related manoeuvres. Thus, they most likely represent symptoms of cardiovascular autonomic dysregulation manifesting during cardiopulmonary bypass. In this patient, blood pressure variations terminated spontaneously and remained within an acceptable range without external correction.

Conclusions

When treating patients with multiple sclerosis comorbidity, the potential pressure variability due to cardiovascular autonomic dysregulation should be taken into consideration to avoid increased blood pressure volatility due to overcorrection or undercorrection during cardiopulmonary bypass.

Towards Optimizing Sub-Normothermic Machine Perfusion in Fasciocutaneous Flaps: A Large Animal Study

Machine perfusion has developed rapidly since its first use in solid organ transplantation. Likewise, reconstructive surgery has kept pace, and ex vivo perfusion appears as a new trend in vascularized composite allotransplants preservation. In autologous reconstruction, fasciocutaneous flaps are now the gold standard due to their low morbidity (muscle sparing) and favorable functional and cosmetic results. However, failures still occasionally arise due to difficulties encountered with the vessels during free flap transfer. The development of machine perfusion procedures would make it possible to temporarily substitute or even avoid microsurgical anastomoses in certain complex cases. We performed oxygenated acellular sub-normothermic perfusions of fasciocutaneous flaps for 24 and 48 h in a porcine model and compared continuous and intermittent perfusion regimens. The monitored metrics included vascular resistance, edema, arteriovenous oxygen gas differentials, and metabolic parameters. A final histological assessment was performed. Porcine flaps which underwent successful oxygenated perfusion showed minimal or no signs of cell necrosis at the end of the perfusion. Intermittent perfusion allowed overall better results to be obtained at 24 h and extended perfusion duration. This work provides a strong foundation for further research and could lead to new and reliable reconstructive techniques.

Original Method for Evaluating Endothelial Vasomotor Function of Isolated Vessel in Experiment

We describe a method for experimental assessment of endothelial dysfunction in an isolated using extracorporeal machine perfusion and vasoactive substrates agents (norepinephrine and acetylcholine). Quantitative assessment of endothelial vasomotor dysfunction was proposed, based on registration of changes in volumetric perfusate flow rate through the isolated vessel. Functional activity of the isolated aorta endothelium and total content of stable NO degradation products in blood plasma were studied in outbred white male rats after subtotal liver resection. Impaired vasodilation ability of the aorta and increased content of NO degradation products in blood plasma observed after surgery indicate the development of vasomotor endothelial dysfunction associated with oxidative stress, cholemia, and endotoxemia.

Tissue Viability of Free Flaps after Extracorporeal Perfusion Using a Modified Hydroxyethyl Starch Solution

BACKGROUND

In free flap surgery, tissue is stored under hypothermic ischemia. Extracorporeal perfusion (EP) has the potential to extend storage time and the tissue's perspective of survival. In the present study, the aim is to improve a recently established, simplified extracorporeal perfusion system.

METHODS

Porcine musculus rectus abdominis were stored under different conditions. One group was perfused continuously with a simplified one-way perfusion system for six hours, while the other received only a single flush but no further treatment. A modified hydroxyethyl starch solution was used as a perfusion and flushing solution. Vitality, functionality, and metabolic activity of both groups were analyzed.

RESULTS

Perfused muscles, in contrast to the ischemically stored ones, showed no loss of vitality and significantly less functionality loss, confirming the superiority of storage under continuous perfusion over ischemic storage. Furthermore, in comparison to a previous study, the results were improved even further by using a modified hydroxyethyl starch solution.

CONCLUSION

The use of EP has major benefits compared to the clinical standard static storage at room temperature. Continuous perfusion not only maintains the oxygen and nutrient supply but also removes toxic metabolites formed due to inadequate storage conditions.

Endotoxin-induced changes in expression of cyclooxygenase isoforms in the lamellar tissue of extracorporeally haemoperfused equine limbs

Angiogenesis and sepsis‐related equine laminitis have several features in common. Both events can be induced by endotoxin (lipopolysaccharide— LPS) and both are associated with increased expression of the enzyme cyclooxygenase (COX), of which two isoforms (COX‐1 and COX‐2) exist. To examine the causal relationship between LPS exposure and COX expression and to investigate the tissue distribution of COX in the LPS‐exposed tissue, the technique of extracorporeal haemoperfusion of isolated equine forelimbs was utilized. Perfusion was performed for 10 hr under physiological conditions (control‐perfused limbs, n = 5) and with addition of 80 ng/L of endotoxin (LPS‐perfused limbs; n = 5). After perfusion, samples of lamellar tissue were collected from the dorsal aspect of the hoof wall. Additional control samples were collected from three non‐perfused limbs. Immunohistochemical analysis was performed using antibodies against COX‐1 and COX‐2, and intensity of immunohistochemical staining was scored for each isoform. In the lamellar tissue of control‐ and LPS‐perfused limbs, there was no significant difference in COX‐1 staining intensity and distribution, whereas COX‐2 expression was significantly increased in LPS‐perfused limbs (especially in endothelial cells, fibroblasts and intravasal leucocytes as well as in epidermal basal cells at the base of the primary epidermal lamellae). These results suggest that COX‐2 and its metabolites are involved in the initiation of pathological changes seen in sepsis‐associated events such as sepsis‐related laminitis. In such cases, COX‐2 could therefore be an important therapeutic target; however, early therapy may be required as increase in COX‐2 expression occurs within 10 hr after LPS exposure.

Extracorporeal perfusion of isolated organs of large animals - Bridging the gap between in vitro and in vivo studies

Since the early 20th century, extracorporeal perfusion of large animal organs has been used to investigate a broad variety of research questions, thereby overcoming common drawbacks of in vitro studies without suffering from ethical concerns associated with live animal research. The technique is in accordance with the 3R principles and represents an excellent opportunity to investigate the physiology of organs in detail under standardized conditions. It is also suitable for the translation of basic pre-clinical research into a more relevant arena prior to or avoiding live animal research altogether. Furthermore, organ perfusion has also been an important tool in developing methods of organ preservation for transplantation surgery. Yet, due to the nature of the experiments, only short-term observations can be made and while cells are still exposed to their regional secretome, the whole organ itself is isolated from the body and correlations between organ systems cannot be taken into consideration. This review gives an overview over the history of extracorporeal perfusion of large animal organs and limbs, highlighting major achievements in the field and discussing different experimental set-ups. Advantages and limitations of the technique are presented. Prospective future research perspectives, which may include tracking of specific cell types and study of their distinct behavior towards different stimuli, are given to illustrate the relevance of this method.