Cardiothoracic Anesthesia and Intensive Care

At the section of cardiothoracic anesthesia and intensive care, clinically oriented research is performed in collaboration mainly with the section of cardiothoracic surgery and the department of anesthesiology and intensive care. The projects involve cardiothoracic anesthesiologists and surgeons as well as perfusionists. 

Contact: Fredrik Lennmyr, Associate Professor

Other postgraduates

Ulrica Alström, MD, PhD, Consultant Anesthesiologist
Ove Jansson, MD, PhD, Consultant Anesthesiologist
Thomas Tovedal, PhD, Perfusionist
 

Experimental selective antegrade cerebral perfusion (SACP)

Thomas Tovedal, Mark Lubberink*, Arvid Morell*, Ove Jonsson, Gunnar Myrdal, Vitas Zemgulis, Sergio Estrada*, Gunnar Antoni*, Stefan Thelin, Fredrik Lennmyr

* Collaboration with Departments of Hospital Physics and PET-center.

Aortic arch surgery requires circulatory arrest and cerebral protection relies on deep hypothermia, selective perfusion of the brain by antegrade (SACP) or retrograde routes or combinations thereof. Perioperative morbidity and mortality is substantial. 

Based on the clinical uncertainty regarding the lower ischemic threshold during SACP, we have focused our scientific efforts on defining the metabolic response to low flow SACP. This is of particular clinical relevance, since high flows may be associated with unwanted side effects such as hypertension, edema and increased risk for embolism. 

In order to study the cerebral response to SACP, we use magnetic resonance imaging and spectroscopy as well as near-infrared light spectroscopy (NIRS) and microdialysis. 

The group has previously published experimental findings supporting the use of SACP at 20 degrees centigrade vs. hypothermic cardiac arrest and SACP at moderate hypothermia [1]. 

Recently, we were able to substantiate the flow level of 6 ml/kg/min as a potential ischemic threshold at 20 degrees centigrade in the same model, and we also described previously unknown regional variations in perfusion that could be of pathogenic importance to the occurrence of intraoperative cerebral ischemia [2]. 

Currently, we analyze further the lower flow limits of SACP using PET technique and we aim to continuing the scientific efforts to outline the patophysiology of neurological damage following SACP during the next years. 

Publications 

  1. Jonsson O, Myrdal G, Zemgulis V, Valtysson J, Hillered L, Thelin S: Selective antegrade cerebral perfusion at two different temperatures compared to hypothermic circulatory arrest--an experimental study in the pig with microdialysis. Interact Cardiovasc Thorac Surg 2009, 8(6):647-653.
  2. Jonsson O, Morell A, Zemgulis V, Lundstrom E, Tovedal T, Einarsson GM, Thelin S, Ahlstrom H, Bjornerud A, Lennmyr F: Minimal Safe Arterial Blood Flow During Selective Antegrade Cerebral Perfusion at 20 degrees Centigrade. Ann Thorac Surg. 2011 Apr;91(4):1198-205.
  3. Tovedal T, Jonsson O, Zemgulis V, Myrdal G, Thelin S, Lennmyr F.: Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass. Interact Cardiovasc Thorac Surg 2010;11(5):561-566
  4. Tovedal T, Myrdal G, Jonsson O, Bergquist M, Zemgulis V, Thelin S, Lennmyr F. Experimental treatment of superior venous congestion during cardiopulmonary bypass. Eur J Cardiothorac Surg. 2013 Sep;44(3):e239-44

  

One-lung ventilation with capnothorax 

Henrik Reinius**, Joao Baptista Borges**, Lena Jideus, Filip Fredén**, Anders Larsson**, Göran Hedenstierna**, Fredrik Lennmyr
 

**Collaboration with the Department of Anesthesiology and the Hedenstierna Laboratory.

Airway separation with unilateral lung closure (one-lung ventilation, OLV) is used to facilitate exposure during lung surgery and thoracoscopic surgery. In the latter case, insufflation of carbon dioxide may provide further optimization by compressing the lung. The respiration needs to be managed with one lung only and its related problem regarding CO2 elimination and oxygenation. There may also be a mismatch between perfusion and ventilation during OLV. There may be important hemodynamic side effects that require treatment. We have developed a model to explore the physiology during these conditions (1). The model has been used further to define the optimal conditions for this kind of ventilation and will be included in an upcoming doctoral thesis (Henrik Reinius)

  1. Reinius H, Borges JB, Fredén F, Jideus L, Camargo ED, Amato MB, Hedenstierna G, Larsson A, Lennmyr F. Real-time ventilation and perfusion distributions by electrical impedance tomography during one-lung ventilation with capnothorax. Acta Anaesthesiol Scand. 2015 Mar;59(3):354-68.
     

Venous congestion and cerebral perfusion in cardiopulmonary bypass 

Thomas Tovedal, Ove Jonsson, Gunnar Myrdal, Vitas Zemgulis, Stefan Thelin, Fredrik Lennmyr

Venous congestion is a threat to perfusion during cardiopulmonary bypass (CPB), and occasionally venous drainage cannot be adequately ensured in the clinical setting. There are cases of severe hypoperfusion related to impaired drainage, and there is a risk of cerebral hypoperfusion. In rare cases, venous congestions may escape detection despite severe reduction of the cerebral perfusion [1]. However, the experimental and clinical literature data are scarce, and it was desirable to approach the problem from an experimental angle.  

We have described the effects of progressive venous congestion on cerebral non-invasive monitoring with near-infrared light spectroscopy (NIRS) and invasive metabolic measures with microdialysis. Measurable signs of ischemia were found with venous congestion, with a notable inter-individual variation. Furthermore, we were able to demonstrate that standard flow monitoring of the CPB circuit may allow undetected flow changes between the venous cannulas, a novel piece of information of large clinical importance since this challenges the current methods of ensuring SVC drainage in practice [2]. We have also compared different strategies to preserve cerebral perfusion pressure during venous obstruction and found that vasopressor treatment can be useful to increase the perfusion margins [3].

Further research on organ perfusion and monitoring during CPB is warranted and the project is suitable to both physicians and perfusionists. In the future, we aim to facilitate clinical research on cardiothoracic patients operated with CPB, and hope to be able to translate the experimental findings into clinical practice. 

Publications 

  1. Jonsson O, Morell A, Zemgulis V, Lundstrom E, Tovedal T, Einarsson GM, Thelin S, Ahlstrom H, Bjornerud A, Lennmyr F: Minimal Safe Arterial Blood Flow During Selective Antegrade Cerebral Perfusion at 20 degrees Centigrade. Ann Thorac Surg 2011.
  2. Tovedal T, Jonsson O, Zemgulis V, Myrdal G, Thelin S, Lennmyr F: Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass. Interact Cardiovasc Thorac Surg 2010, 11(5):561-566. 
  3. Tovedal T, Myrdal G, Jonsson O, Bergquist M, Zemgulis V, Thelin S, Lennmyr F. Experimental treatment of superior venous congestion during cardiopulmonary bypass. Eur J Cardiothorac Surg. 2013 Sep;44(3):e239-44


Hyperglycemia and cerebral ischemia 

Maria Molnar***, Rickard Lindblom, Lars Wiklund***, Fredrik Lennmyr 

*** Collaboration with the department of anesthesiology

Hyperglycemia is associated with increased complication rate after cardiac surgery and tight glycemic control is established in the postoperative stage. Furthermore, hyperglycemia is particularly harmful to the brain in case of focal ischemia-reperfusion, but to what extent hyperglycemia aggravates the brain damage after cardiac arrest is not clear.

This team investigates the impact of hyperglycemia on ischemic brain injury in terms of focal as well as global insults [1-3]. In 2015, Maria Molnar defended her doctoral thesis, and the current focus is the gene expression profile after hyperglycemic cardiac arrest.  

Publications 

  1. Molnar M, Lennmyr F: Neuroprotection by S-PBN in hyperglycemic ischemic brain injury in rats. Ups J Med Sci 2010, 115(3):163-168.
  2. Lennmyr F, Molnar M, Basu S, Wiklund L: Cerebral effects of hyperglycemia in experimental cardiac arrest. Crit Care Med 2010, 38(8):1726-1732.
  3. Molnar M, Bergquist M, Larsson A, Wiklund L, Lennmyr F: Hyperglycaemia increases S100β after short experimental cardiac arrest. Acta Anaesthesiol Scand. 2014 Jan;58(1):106-13
     

Hemostasis and cardiac surgery

Axel Dimberg, Elisabeth Ståhle, Christina Christersson, Ulrica Alström

The progression of aortic stenosis involves both blood coagulation and fibrinolysis. In an ongoing study, patients undergoing heart surgery due to aortic stenosis and coronary artery disease are being investigated. To improve the medication for the individual patient during and after heart surgery the blood coagulation and platelet functions are studied.