The Cardiovascular Research Laboratory
Led by Prof. Niels H Secher, the Cardiovascular Research Laboratory is dedicated to research into cardiovascular physiology. Main focus areas are:
- Peri-operative pathophysiology
- Brain blood flow and metabolism
- Human cardiovascular physiology
- Postoperative pain
The Cardiovascular Research Laboratory is part of The Copenhagen Muscle Research Centre (CMRC) and collaborates extensively nationally as well as internationally.
Awards in 2010
- Assoc. Prof. James Fisher: Research Recognition award from neural control and autonomic regulation section.
- Post. doc. Peter Rasmussen: Early Career Author Prize, Exp. Physiol.
Areas of research
Invasive procedures are used for studies on human cardiovascular control with focus on cerebral blood flow and metabolism. Furthermore, methods are introduced to reduce peri-operative blood loss.
Cardiovascular variables are evaluated for their ability to detect blood loss or reduction in central blood volume brought forth on a tilt table or during lower body negative pressure. A central issue has been to define “normovolaemia”.
In supine humans the heart operates on the upper ceiling of the Starling curve and normovolaemia can be defined as the volume load that does not limit cardiac output (or stroke volume or venous oxygen saturation) for the supine patient. Apparatus for continuous recording of cardiac output is therefore of interest.
Cerebral blood flow and metabolism have been evaluated during exercise to elicit robust “activation” compared with during anaesthesia. It is demonstrated that physical exercise requires an approximately 20 % increase in cerebral blood flow and metabolic rate for oxygen. This reflects that low intensity exercise is associated with increasing cerebral oxygenation, while cerebral oxygenation decreases during maximal exercise, since marked hyperventilation reduces arterial carbon dioxide tension and therefore cerebral blood flow at the same time as the metabolic rate for oxygen is elevated.
Cerebral blood flow and oxygenation are also vulnerable to a lowering of blood pressure. The so-called lower level of cerebral Auto-regulation manifests at a blood pressure of approximately 80 mmHg when the lowering of blood pressure is a result of a reduction of the central blood volume.
On the other hand, if lowering of blood pressure is by pharmacological intervention (as with anaesthetics) and the central blood volume (and cardiac output) is preserved, the blood pressure may be very low without affecting the brain. In surgical procedures for which there may be significant blood loss, or when the central blood volume is reduced because of positioning of the patient, it is of interest to follow brain oxygenation, e.g. by near infrared spectroscopy.
Cerebral metabolism is measured both in volunteers and in patients during anaesthesia from blood sampling via a retrograde internal jugular venous catheter. It is demonstrated that the brain takes up and metabolizes lactate in proportion to its arterial concentration, probably by way of an influence from adrenaline. Furthermore, by using stable isotopes, it is demonstrated that brain anaerobic metabolism (brain lactate release) may account for as much as 10% of the brain’s energy turnover.
Volume enhancement with Voluven® has, in pigs, been found to elicit uncontrollable hemorrhage following liver trauma. Conversely, it seems that survival of the massively bleeding patient is increased following timely administration of plasma and platelets together with red blood cells.