Haemorrhagic pituitary tumours

In a group of 69 patients with pituitary tumours, 12 were found to have evidence of intratumoral haemorrhage on MRI, characterized by high signal intensity on short TR/TE sequences. This was verified in all but 1 patient. The majority of the bleedings occurred in macroadenomas. Five (42%) were prolactinomas and 4 (33%) were non-functioning adenomas. There were 2 GH- and 1 ACTH-secreting tumours. All 5 patients with prolactinomas were on bromocriptine medication. Two of the patients had a clinical picture of pituitary apoplexy. The haemorrhage was not large enough to prompt surgery in any of the patients. However, surgical verification of the diagnosis was obtained in 5 cases, while 6 patients were examined with follow-up MRI.     

Platelets as targets of snake venom metalloproteinases

For centuries snake venoms have been known to interfere with haemostasis and this is now known basically due either to toxins activating/inhibiting clotting factors, having effects on blood vessels or interfering with platelet function. In this short review, the interaction of one major group of toxins, the snake venom metalloproteinases, with platelets is considered. This is relevant for understanding the mechanism of haemorrhage induced by these toxins.     

Intraparenchymal blood-fluid levels in traumatic intracerebral haematomas

Summary Blood-fluid levels within the cerebral parenchyma are observed more frequently on CT and MRI in traumatic intracerebral haematomas than in those of other aetiologies. The intraparenchymal blood-fluid interface can be formed without a fluid cavity. It is suggested that the blood-fluid levels represent layering of red blood cells within areas of contusion necrosis as well as extensive contusion oedema. The more extensive the damage to brain tissue, the more often blood-fluid levels formed. A poorer outcome can be therefore predicted when an intraparenchymal blood-fluid interface is seen.     

Treatment of massively bleeding patients: introducing real‐time monitoring,transfusion packages and thrombelastography (TEG®)

Background Continued haemorrhage remains a major cause of mortality in massively transfused patients, many of whom develop coagulopathy. When reviewing transfusion practice for these patients at our hospital, more than 10% received a suboptimal transfusion therapy and survivors had a higher platelet count than non‐survivors. We therefore speculated whether the blood bank could improve its service and hence improve the outcome. Methods The blood bank introduced monitoring the delivery of blood products and contacted the clinician provided there was an imbalance in the transfusion practice. For massively bleeding patients, transfusion packages, encompassing 5 red blood cells, 5 fresh frozen plasma and 2 platelet concentrates was introduced to improve haemostatic competence. The thrombelastograph (TEG) was implemented, aiding in the diagnosis and treatment of coagulopathy. Results The fraction of suboptimally transfused patients declined from > 10% to < 3%. The transfusion package administered intraoperatively to patients operated for a ruptured abdominal aortic aneurysm resulted in decreased postoperative transfusion requirements and improved 30‐day survival (66% vs. 44%) compared to controls. Only performing TEG in patients with a significant bleeding as judged by the anaesthetist reduces the number of analyses by ~85%, whereas those patients with coagulopathy remain identified. The TEG showed 97% predictability in identifying a surgical cause of bleeding in postoperative patients. Ten percent of the massively bleeding trauma patients had hyperfibrinolysis as the major cause of bleeding, whereas 45% were hypercoagulable. Conclusion The initiatives from the blood bank has improved the transfusion practice and, hence, survival in massively transfused patients at our hospital.     

Cardiovascular and hormonal changes following haemorrhage in the anaesthetized Brattleboro rat with an extracorporeal circulation

An extracorporeal circulation technique was developed for use in rats to provide equilibrated blood samples for multiple hormone assays. The inclusion of the extracorporeal circulation did not significantly alter arterial blood pressure, cardiac output, heart rate or central venous pressure in either Brattleboro rats with hereditary diabetes insipidus (BDI) or normal rats of the parent Long Evans (LE) strain. Plasma adrenaline and noradrenaline levels did not alter in either BDI or LE rats following inclusion of the extracorporeal circulation but the vasopressin concentration rose significantly in the LE rats. The impaired recovery of the mean arterial blood pressure following haemorrhage in the BDI rats compared with normal LE animals was not further influenced by the inclusion of the extracorporeal circulation. Plasma vasopressin and adrenaline (but not nor-adrenaline) levels were significantly raised during, and after, haemorrhage in the LE rats while in the BDI rats only plasma adrenaline levels were significantly increased. These results show that the insertion of an extracorporeal circulation into an anaesthetized BDI or LE rat does not adversely affect the cardiovascular system despite the increase in baseline plasma vasopressin concentration in normal rats, and its subsequent removal provides an additional equilibrated blood sample for multiple hormone assay within the same animal. The increased release of both adrenaline and vasopressin (but not noradrenaline) after haemorrhage in the same animal is detected using this technique, and the importance of vasopressin to the normal recovery process confirmed.     

Ionic and haemodynamic changes influence the release of the excitatory amino acid glutamate in the posterior hypothalamus

The push-pull technique was used to investigate the release of the excitatory amino acid glutamate in the posterior hypothalamic area of the conscious rat. The hypothalamus was superfused through the pushpull cannula with artificial cerebrospinal fluid (CSF), and the superfusate was collected in time periods of 10 min when ionic conditions in the CSF were changed, or in short periods of 3 min when blood pressure changes were evoked. The mean glutamate release rate was 2.8 + 0.7 pmol/min. Depolarization by hypothalamic superfusion with CSF containing 50 mM K⁺ enhanced the release of glutamate in the presence of Ca²⁺. The K⁺-induced release was attenuated by 40% when the hypothalamus was superfused with Ca²⁺-free CSF. Replacement of Ca²⁺ by Mg²⁺ abolished the K⁺-induced release of glutamate. Hypovolaemia elicited by haemorrhage enhanced the release rate of glutamate. Similarly, a hypotension elicited by i.v. injection of chlorisondamine (3 mg/kg) led to a pronounced and permanent enhancement in glutamate release. The effects of hypovolaemia and chlorisondamine on glutamate release were abolished in aortic denervated rats, indicating that this response is due to a decrease of impulse generation in baroreceptors. A hypovolaemia elicited by blood infusion did not affect the release of glutamate. Similarly, a pronounced pressor response to phenylephrine (15 /kg per minute) infused intravenously for 9 min was ineffective.The results show that the K⁺-induced release of glutamate in the hypothalamus is dependent on the presence of Ca²⁺. The increase in glutamate release rate by hypovolaemia or chlorisondamine suggests that the glutamatergic neurons in the posterior hypothalamic area respond to unloading of aortic baroreceptors and possess a counteracting, hypertensive function.     

Combined endovascular therapy of ruptured aneurysms and cerebral vasospasm

We describe two patients with subarachnoid haemorrhage due to a ruptured intracranial aneurysm and severe symptomatic vasospasm. The aneurysm was occluded with detachable coils followed by intra-arterial infusion of papaverine to treat vasospasm as an one-stage procedure. There was significant resolution of the vasospasm. The long-term clinical outcome in one patient was excellent, the other still has minor deficits. Combined endovascular aneurysm therapy followed by intra-arterial spasmolysis with papaverine is a technically feasable therapeutic alternative in patients with symptomatic vasospasm. Received: 5 November 1999/Accepted: 12 July 2000     

The purification and partial characterisation of two novel metalloproteinases from the venom of the West African carpet viper, Echis ocellatus.

Separation of previously uncharacterised Echis ocellatus venom by phenyl-Superose FPLC (Fast Liquid Protein Chromatography) yielded eight protein fractions. Three of these displayed high proteolytic activity when assayed by in vivo and in vitro assays (including enzyme linked immunosorbant assay), and were further separated using Superdex 75 and Mono-Q FPLC. This resulted in the purification of a non-haemorrhagic 24 kDa metalloproteinase (EoVMP1, pI 7.0), and a haemorrhagic 56 kDa metalloproteinase (EoVMP2, pI 5.5). Following tryptic digest, short amino acid sequences of EoVMP1 and EoVMP2 were obtained using Edman degradation. Both sequences displayed homology when aligned with existing snake venom metalloproteinases (SVMPs). The strong homology observed among previously well-characterised SVMPs suggests that principles governing the interaction of substrates and inhibitors are likely to be similar for EoVMP1, EoVMP2 and all members of the reprolysin family.     

The iTClamp in the management of prehospital haemorrhage

IntroductionBleeding remains a leading cause of death in trauma patients. The iTClamp is a temporary wound closure device designed to control external bleeding within seconds of injury. We describe our experience using this device on 10 patients in the prehospital environment.MethodsWe have implemented the iTClamp for prehospital use through our physician-staffed helicopter emergency medical service (HEMS). Indications were massive bleeding that could not be controlled with an ordinary compressive bandage or a haemostatic bandage.ResultsTen patients were treated with the iTClamp. Seven patients had a severe head injury due to various traumas, one patient had a neck injury from a disk cutter, one patient had an open chest wound and one patient had an open femur fracture. After applying the iTClamp, bleeding was controlled in 90% of these patients (n = 9), with complete cessation reported in 60% (n = 6), partial cessation with adequate control reported in 30% (n = 3); in one patient, the bleeding could not be controlled with the iTClamp alone. It took an average of 10 s to apply the iTClamp, and the average usage satisfaction score was 7.7.ConclusionWe conclude that the iTClamp is a safe, fast and useful tool for stopping or controlling external blood loss in our series of prehospital patients. Further studies of the iTClamp are needed to determine which patients might benefit from this device.     

Risk of bleeding after dentoalveolar surgery in patients taking anticoagulants

To avoid increasing the risk of thromboembolic events, it is recommended that treatment with anticoagulants should be continued during dentoalveolar operations. We have evaluated the incidence of bleeding after dentoalveolar operations in a prospective study of 206 patients, 103 who were, and 103 who were not, taking anticoagulants. Seventy-one were taking thrombocyte aggregation inhibitors and 32 vitamin K antagonists. Patients were treated according to guidelines developed at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. The operations studied included surgical extraction (when the surgeon had to incise the gingiva before extraction), non-surgical extraction, apicectomy, and placement of implants. Patients were given standard postoperative care and those taking vitamin K antagonists used tranexamic acid mouthwash postoperatively.