Ernil Hansen

Blood irradiation for intraoperative autotransfusion in cancer surgery: demonstration of efficient elimination of contaminating tumor cells.

BACKGROUND: Intraoperative blood salvage is contraindicated in cancer surgery because of contaminating tumor cells and the risk of systemic dissemination. On the basis of the radiosensitivity of cancer cells, irradiation of salvaged blood with 50 Gy is proposed as a way to allow return of salvaged blood.

Central venous catheter placement: comparison of the intravascular guidewire and the fluid column electrocardiograms

Background and objective: Placement of central venous catheters in patients is associated with several risks including endocardial lesions and dysrhythmias. Correct positioning of central venous catheters in the superior vena cava is essential for immediate use. The objective of a first study was to evaluate the signal quality of an intravascular electrocardiogram (ECG) during position control using a guidewire compared with the customary fluid column-based ECG system, and to assess its efficacy of correct placement of the central venous catheter. A second study tested if dysrhythmias can be avoided by intravascular ECG monitoring during catheter and guidewire advancement. Methods: The jugular or subclavian vein of 40 patients undergoing heart surgery or who were being treated in the intensive care unit was cannulated. Intravascular ECGs were recorded during position control, and guidewire and water column lead were compared in the same patient with regard to the quality of the ECG reading and P-wave enhancement. In another 40 patients, the guidewire was inserted only 10 cm and the central venous catheter advanced under guidewire ECG control. Correct position of all the central venous catheters was confirmed by chest radiography. Results: All central venous catheters were correctly positioned in the superior vena cava. For the same catheter position, the P-wave was significantly larger in the guidewire ECG than in the fluid column system. No changes in the quality of the ECG were detected when the guidewire was advanced or withdrawn by 1 cm relative to the catheter tip. Cardiac dysrhythmias were not seen during ECG-monitored advancement of the guidewire. Conclusions: ECG quality using a guidewire lead is superior to the water column-based system. Furthermore, it is independent from the exact position of the guidewire as related to the tip of the catheter. Using intravascular guidewire ECG during advancement can prevent induction of dysrhythmias.

Intraoperative blood salvage in cancer surgery: safe and effective?

To support blood supply in the growing field of cancer surgery and to avoid transfusion induced immunomodulation caused by the allogeneic barrier and by blood storage leasions we use intraoperative blood salvage with blood irradiation. This method is safe as it provides efficient elimination of contaminating cancer cells, and as it does not compromise the quality of RBC. According to our experience with more than 700 procedures the combination of blood salvage with blood irradiation also is very effective in saving blood resources. With this autologous, fresh, washed RBC a blood product of excellent quality is available for optimal hemotherapy in cancer patients.

Levetiracetam compared to phenytoin for the prevention of postoperative seizures after craniotomy for intracranial tumours in patients without epilepsy

Anticonvulsant drugs are frequently given after craniotomy. Phenytoin (PHT) is the most commonly used agent; levetiracetam (LEV) is a new anticonvulsant drug with fewer side effects. To compare the incidence of seizures in patients receiving either prophylactic PHT or LEV perioperatively, 971 patients undergoing a craniotomy were analysed retrospectively during a 2-year period. PHT was used routinely and LEV was administered when PHT was contraindicated. Seizures documented during the first 7 days after craniotomy were considered. A total of 235 patients were treated with an antiepileptic drug: 81 patients received LEV, and 154 patients, PHT. Two patients receiving LEV (2.5%) and seven receiving PHT (4.5%) had a seizure despite this treatment. No patient had a documented side effect or drug interaction. The data show that LEV may be an alternative option in patients with contraindications to PHT.

Antigen-Specific Electrophoretic Cell Separation (ASECS): Isolation of human T and B lymphocyte subpopulations by free-flow electrophoresis after reaction with antibodies

The electrophoretic mobility of human lymphocytes can be reduced by incubation with surface antigen specific antibodies under non-capping conditions. This renders subpopulations of human peripheral blood lymphocytes accessible to separation by free-flow electrophoresis. After reaction of lymphocyte preparations with anti-IgM antibody and a fluorescent second antibody, B lymphocytes showed a considerable shift in position in preparative cell electrophoresis and could be separated with high yield, purity and vitality. Similarly, a T cell subpopulation reactive with the monoclonal antibody T811 could be isolated, even though only small amounts of this antibody were bound, by using a double-sandwich method. Non-specific antibody uptake via Fc-receptors did not contribute to the observed shift of antibody-labelled cells to lower electrophoretic mobility. Flow cytometric analysis showed that cells were separated according to their antigen density. Thus cell electrophoresis can be used to separate antibody-labelled cells. With a flow rate of 100,000 cells/sec this method has a much higher separation capacity than fluorescence-activated cell sorting. The described method should be applicable to the separation of a wide range of cell populations for which specific antibodies are available.

Washing of banked blood by three different blood salvage devices

BACKGROUND: Storage lesions in red blood cells (RBCs) lead to an accumulation of soluble contaminants that can compromise the patient. Organ failures, coagulopathies, and cardiovascular events including lethal cardiac arrest have been reported, especially with massive transfusion or in pediatric patients. Washing improves the quality of stored RBCs, and autotransfusion devices have been proposed for intraoperative processing, but these devices were designed for diluted wound blood, and limited data on their performance with RBCs are available.

Quality Management in Blood Salvage: Implementation of Quality Assurance and Variables Affecting Product Quality

Implementation of quality management in intraoperative blood salvage with controls of product and process quality supports early recognition and repair of dysfunction if respective actions are laid down in the quality management handbook. In order to avoid insufficient quality and to improve process quality, a broad understanding of the processes and of the variables affecting quality is needed, which is based on experimental tests. For this purpose the use of fresh whole blood as test blood and of protein as parameter for determination of the plasma elimination rate is favorable over outdated banked blood and free hemoglobin. Tested this way, the process of blood collection by suction is by far not as harmful to RBCs as expected. Partially filled bowls, lower wash volumes, or a fastened filling or washing should be avoided. Plasma washout can be improved by higher wash volumes or by slower filling and washing, which avoids increased loss of RBCs. Quality management which is based on a better understanding of the procedure as well as quality controls can help to supply high-quality blood for optimal hemotherapy by blood salvage.

5c Autologous haemotherapy in malignant diseases

Pre-donation of blood in cancer patients is effective and recommendable, but is limited by tumour anaemia, urgent scheduling of surgery and variable blood loss resulting in discarded autologous blood or homologous transfusions. Intra-operative autotransfusion is considered to be contraindicated in cancer surgery. This was confirmed by the recent demonstration of the frequent existence of vital, proliferating, invasive and tumorigenic tumour cells in high numbers in the blood shed during surgery of various cancers. Leukocyte depletion filters are unable to guarantee complete elimination of contaminating tumour cells because of the limited reduction rates. The radiosensitivity of the nucleated tumour cells, in contrast to the radioresistance of the unnucleated red blood cells, can be used for efficient elimination. For 50 Gy a 12 decade reduction can be calculated from radiosensitivity data, and experimentally a 10 decade reduction has been demonstrated, sufficient to eliminate any supposed tumour cell contamination. This combination of two well-established methods, intra-operative blood salvage and blood irradiation, in clinical practice proved to be an effective, practical and safe procedure for using autologous blood in cancer patients.

Characterization of rat bone marrow lymphoid cells. I. A study of the distribution parameters of sedimentation velocity, volume and electrophoretic mobility

Various cell populations in rat bone marrow were characterized by means of a two dimensional separation using velocity sedimentation and free flow electrophoresis and by electrical sizing of the separated cells. Up to 4.5 mm/hr five different populations with discrete distributions in volume (coefficient of variation 10% to 13%) and sedimentation velocity (coefficient of variation 6% to 10%) were observed. Three of the small sized populations represented lymphocytes and small normoblasts and two of the larger sized populations represented myeloid cells. Almost all of these cells were in the G0/G1 cycle phase. In the faster sedimenting fractions which contained immature myeloid, erythroid and undefined blast cells and two S phase populations, discrete volume distributions were not evaluated. The cell populations with homogeneous volume (particularly the small lymphocytes) showed high density variations which condiserably impair the separation resolution. The cells sedimenting slower than 3.5 mm/hr were further separated by means of free flow electrophoresis into three peaks differing in electrophoretic mobility (EPM). The peaks of low and high EPM contained two populations and the peak of medium EPM contained three populations all characterized by normal volume distributions of uniform coefficient of variation between 11% and 14%. The small cells in the peaks of high and medium EPM were normolblasts and the other cells were lymphocytes. The biological significance of these results is discussed.

Practicability and safety of intra‐operative autotransfusion with irradiated blood

local anaesthetics. These electrodes may be sited intra-operatively by the surgeon, or percutaneously by the anaesthetist when the anterior approach to surgery is preferred. While this technique has a very low false negative rate, there are sporadic repom ofpostoperative paraplegia despite unchanged intra-operative sensory evoked potential traces. Therefore assessing the integrity of the motor pathways to complete the picture is desirable. Animal studies have also shown the motor evoked potential to be an earlier predictor of impending damage. The motor evoked potential are recorded peripherally in response to stimulation of the cerebral cortex or the spinal cord. Electrical stimulation of the motor cortex is technically difficult and not every patient is suitable for electrical stimuli. The magnetic stimulator, whdst non-invasive and painless evokes responses which similar to those from electrical stimuli in that they are very anaesthetic sensitive, particularly those responses recorded &om the lower lunbs. At the Royal National Orthopaedic Hospital we have developed a technique ofstimulating the existing bipolar epidural electrode and recording from a lower limb muscle. Compound muscle action potentials were chosen because: the response amplitude would be greater than for neurogenic potentials; the likelihood ofantidromic sensory conduction would be minimised. Both the stimulus pattern and the anaesthetic technique are critical to the recording of reproducible motor potentials. Initial attempts using single stimuli were unrewarding but the addition of a second stimulus, 1-2 ms alter the first dramatically augmented the response. Much lower stimulating currents are also used; avoiding nitrous oxide and the halogenated agents is also findamend to the success of this technique. A total intravenous anaesthetic is used with propfol and fentanyl or alfentanil and more recently remifentanil. An intubaang dose ofmuscle relaxants is used and thereafter relaxants are avoided; stable intra-operative motor evoked potential monitoring is now possible with this technique. There is not yet enough experience to recommend criteria for interpreting these potentials in terms of significance for postoperative neurological status and this must await systemic observations during regular clinical use in association with sensory evoked potentials. It has however proved useful in allowing intra-operative monitoring in patients with sensorimotor neuropathy. An amplitude drop ofgreater than 50% in a sensory potential is deemed significant and warrants immediate attention both from the surgeon and the anaesthetist. Cord perfusion is all important and normotension is essential. The ultimate responsibility, whether to reduce the distraction or to remove metal work, rests with the surgeon. The advantages ofspinal cord monitoring are not confined to orthopaedic surgery. It is also ofvalue in brachd plexus surgery and mjor thoracic vascular surgery.