Neurochirurgia 18 (1915), 20-25 © Georg Thieme Verlag Stuttgart

New Possibilities of Controlled Hypotension in Neurosurgery* B. Niedermeier, W. Grote

Summary The position of controlled hypotension in neurosurgery is reviewed including both the new and old techniques and the drugs used. A special emphasis is placed on our use of sodium Nitroprusside which allows short lived, but very significant lowering of the blood pressure. Using this technique it was possible in three cases where rebleeding of the aneurysm occurred at operation and in a further six cases of considerable arterial haemorrhage, to, 'dry' the field of operation i.e. reduce the bleeding to such an extent that satisfactory orientation and quick and accurate handling of the emergency could be achieved.

velles ainsi que les agents chimiques utilisés, sont décrits. On insiste particulièrement sur notre procédé au sodium-nitroprusside qui permit des hypotensions radicales et de courte durée. Cette technique permit dans 3 cas d'anévrysmes rompus peropératoirement et dans 6 autres cas d'hémorragie artérielle abondante d'assécher le champ opératoire au point de permettre une orientation rapide de l'acte chirurgical.

The technique of controlled hypotension is indispensable for numerous operations. In general it not only serves the purpose of reducing intra-operative bleeding, thus creating better operating conditions for the surKey words: controlled hypotension - aneurysm geon and also saving the patient the need for vascular operation transfusion, but it also enables surgical interventions to be carried out at lower risk, espeZusammenfassung cially where it is a case of dealing with intracranial malformations (angiomas and aneuDer Stand der kontrollierten Hypotension in rysms). The danger of spontaneous perforader Neurochirurgie, ältere und neuere Techniken und die verwendeten Pharmaka werden darge- tion of the aneurysmal sac or of the arteristellt. Insbesondere wird auf unser Verfahren mit alized vein during the dissection is radically Na-Nitroprussid eingegangen, das kurzfristige und reduced. Various techniques have been evolvsehr radikale Blutdrucksenkungen ermöglicht. Mit ed; in 1946 Gardner introduced blood-letting dieser Technik gelang es, in drei Fällen von intraoperativ perforierten Aneurysmen und in 6 for lowering blood pressure; Griffiths and weiteren Fällen starker arterieller Blutungen das Gillies used high spinal anaesthesia, and Operationsfeld so weit »trockenzulegen«, daß eine in 1950 Enderby described ganglionic blockOrientierung und schnelles und gezieltes Handeln ing by means of drugs. Moreover, the cardiomöglich wurden. depressive side-effect of anaesthetics such as Halothane, for instance, was turned to good account, and finally inclined positions of the Résumé patient were employed in combination with Nouvelles possibilités de l'hyotension contrôlée the above-mentioned methods. en neurochirurgie. * Presented in honour of Prof. Dr. med. P. L'état actuel de l'hypotension contrôlée en Röttgen, Bonn, on the occasion of his 65th neurochirurgie, les techniques anciennes et noubirthday.

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Anästhesie-Abteilung (Leiter: Prof. Dr. L. Stöcker) und Neurochirurgische Klinik (Direktor: Prof. Dr. W . Grote) am Universitätsklinikum Essen

New Possibilities of Controlled Hypotension in Neurosurgery

ment of the clip, it was possible that the cerebral blood flow was reduced for too long. Neurological and mental symptoms then manifested themselves especially in elderly patients or those with circulatory disorders. Häggendabl and co-workers therefore demand a minimum perfusion pressure of 40 to 60 mm Hg for those with a sound circulatory system. The further side-effects of a protracted and deep hypotension are reduced renal and coronary blood flow with their consequences, thromboses in cerebral vessels and, after return to normal pressure, frequently a cerebral hyperaemia, associated with vascular lesions. Encouraged by the invariably good results, we shall be describing below the procedure we follow, with an account of three cases of ruptured aneurysms and six further cases accompanied by fairly severe arterial bleedings. For lowering the blood pressure we use, in addition to the ganglion-blocking agent Trimetaphan, sodium nitrg-prusside. The former fulfils the technical criteria of hypotension, as listed above, with only a few reservations, and sodium nitro-prusside - based on our experience - fulfils them completely. By inhibiting the vasoconstrictors the ganglion-blocking agents produce vasodilatation and hence a fall in blood pressure. The pulse rate increases; in tachycardias exceeding 120/ min. the coronary blood flow may be endangered. Jordan et al., Styles and others have described a fall in the cardiac minute output, which was particularly severe when Trimetaphan was combined with Halothane. Tachyphylaxis, although not a response to Trimetaphan, has been seen by us on occasions. The hypotensive action and the toxicity of sodium nitro-prusside have been repeatedly investigated during the past 90 years. In 1929 Johnson demonstrated in animal experiments that the haemodynamic action of the nitroprusside is similar to that of the nitrites, due to the fact that it acts directly on the vessel via its NO-group. He was able to rule out

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In regard to controlled hypotension the following technical criteria must be required: 1. The action must be sure, rapid and controllable, 2. the blood flow through the most important organs must remain ensured, 3. a rapid return to normal pressure is essential in order to achieve total haemostasis, and 4. the used drugs should not have any toxic side-effects. In neurosurgery, as already mentioned, controlled hypotension is employed today particularly in the case of vascular operations, besides it is used in the operation of vascular tumours. Formerly, hypotension was recommended also for lowering increased intracranial pressure; today, however, in osmoticallyacting substances and hyperventilation we have better means at our disposal. Harper and Glass demonstrated that the cerebral blood flow remains approximately constant with systolic blood pressure values of up to 70-80 mm Hg. At this pressure it is still possible for an aneurysm to rupture during surgical exposure. Frequently the resulting arterial bleeding is only controlled if the afferent vessel is temporarily closed to have the operating area clear for abolishing the aneurysm and for simultaneous conservation of the afferent or efferent vessels. Only in controlled hypothermia the patient has a chance of surviving the transient ischaemia without fatal consequences. During the past few years further lowering of the blood pressure down to systolic values of between 50 and 60 mm Hg has been used with increasing success. This was introduced in order to prevent a rupturing of the aneurysmal sac during the dissection prior to its ligation. This procedure, if necessary also combined with microsurgical methods, has reduced the incidence rate of intra-operative aneurysmal perforations. On account of the frequently long duration of an intensive hypotension extending from the commencement of mobilising the vessel up to the place-


B. Niedermeier, W. Grote

any influence on the myocardium or the sympathetic nervous system. Page et al. showed that cyanide is developed during the degradation of the nitro-prusside, and in the presence of thiosulphate is converted into thiocynate by enzyme action. Styles et al. have described a rise in the cardiac minute volume in anaesthetized patients; the peripheral resistance is reduced, thus the perfusion is not disturbed at low blood pressure values. A resistence against the effect of nitro-prusside and tachyphylaxis is very seldom, and incompatibilities or allergies are not known. The pulse rate remains unchanged or rises only negligibly. Sodium nitro-prusside has been employed in the therapy of hypertensive crises, such as for example in encephalopathies or phaeochromocytomas. It has also been used in the therapy of cardiac infarctions (Franciosa). The rapid and intensive onset of action of this drug makes its use problematical in internal medicine on account of the frequently necessary checks. For the anaesthetist, who has the possibility of measuring intra-arterial blood pressure precisely, these properties are ideal. From a stock solution made up by the pharmacist (exact instructions by Siegel et al.) 0.01 °/o dilution is prepared, which is infused drop-by-drop. There ia an almost immediate fall in blood pressure. It is possible to attain the desired pressure with a maintenance dose. The total requirement per operation lies between 10 and 200 mg. In 1-3 min. after stopping the infusion the original pressure has been re-attained. For producing narcosis we use the neurolept-anaesthesia, attention being paid to sufficient doses of DHB in the premedication and during the induction. After intubation under succinyl, Alloferin is employed for muscular relaxation and IPPV is carried out with a moderate hyperventilation (checks by control of C 0 2 °/o in the expiration and blood gases). The blood pressure is measured via a

Statham Element in the radial artery. For dehydration we use sorbitol. Already at the beginning of the operation we try to reduce the tendency to bleeding by a moderate lowering of the blood pressure. Values of between 80 and 100 mg Hg suffice for this. In the case of increased intracranial pressure, the blood pressure should not be reduced - as long as the dura has not yet been opened - to below 100 mm Hg, so that an adequate perfusion pressure is ensured. Where there is good muscular relaxation only a few drops of sodium nitro-prusside are sufficient to produce a moderate fall in pressure. During the surgical exposure of the vessels and the aneurysm the blood pressure is slowly reduced further; the systolic values for elderly patients and those with circulatory troubles are around 80 mm Hg. In cases of rupturing of the aneurysmal sac or of a vessel a fairly severe bleeding sets in, which is an obstacle to further operating. Moreover the outcome of the operation gets dubious and the bleeding constitutes an acute danger for the patient. In such a case we lower the blood pressure further until the operating area is dry. With a clear field of vision a clip can now be placed in position. Within a few minutes the blood pressure returns to its normal level. In some cases we have injected vasopressor substances, but we have also seen the same affect without these. The following figures show some original curves taken during operation. The arrows denote the time when the aneurysm perforated or another severe bleeding took place. The times of the radical blood pressure reduction lay between 1 and 10 minutes. The youngest patient was 20 years old, the oldest 66. The blood losses ranged between approx. 300 and 1,800 ml. In two of the nine patients transfusions were necessary. ECG changes did not occur even in the phase of excessive blood pressure reduction. The urine output was considerably reduced, but increased again on the blood pressure rising. Postoperatively, all

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New Possibilities of Controlled Hypotension in Neurosurgery

being discharged he was in good mental and physical condition. In a 20-year-old patient (Fig. 5) with a basilar arterial aneurysm the cavernous sinus and the carotid became ruptured during the very difficult surgical exposure. The clip which had been v/ell positioned under a radical reduction of blood pressure slipped again later on, so that we had to lower the blood pressure once more. Postoperatively, the patient was awake at first, but somewhat slow in her reactions. After about 12 hours she became somnolent and died on the second postoperative day in spite of all efforts made, the symptoms being those of a central dysregulation. Autopsy revealed that the clip was perfectly placed, so that the excessive reduction in blood pressure over a fairly long period of time must

Fig. 1: Patient K. S., ¿J, 34 years old. Lobed aneurysm of the middle cerebral, the size of a cherrystone, fairly severe venous bleeding during surgical exposure. Lowering of blood pressure to 30/0 mm Hg for 8 min. Pre-operative blood pressure between 150/100 and 170/110 mm Hg, postoperative value between 170/110 and 140/90 mm Hg. Blood loss about 500 ml; no transfusion. Postoperative course without complications.

Fig. 2: Patient M. T., 5, 50 years old. Aneurysm of the middle cerebral. A revere arterial bleeding occured during the surgical exposure. Blood pressure reduced to 25/15 mm Hg for 4 min. In the course of the further surgical dissection it was found that the bleeding issued from an aneurysm about the sice of a cherry, with its base at the bifurcation. After clipping, patency of the vessels. Blood loss about 600 ml. No transfusion. No complications.

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the patients were immediately awake. There were no neurological or mental symptoms, even in the ensuing checks. All lab. values deriving from checks carried out daily, lay within the normal range. Seven out nine of these patients treated in this way were transferred back to the general ward on the first postoperative day (Fig. 1-3). Complications were seen in two cases: In a patient, 56 years old (Fig. 4), a pea-sized supraclinoid aneurysm perforated spontaneously during surgical exposure. Aided by an excessive reduction in blood pressure the dissection was concluded and the aneurysm occluded by a clip; the carotid was intact. Postoperatively from the second day on, the patient developed an organic psychosis which lasted several days, accompanied by psychomotor restlessness and mental confusion. On


B. Niedermeier, W. Grote







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Fig. 3: Patient C. D., Ç, 54 years old. Arterial aneurysm of the internal carotid, the size of a bean. Rupture of the carotid when affixing the Heifetz clip. Reduction of blood pressure to > 10 mm Hg for 8 min. After re-clipping the carotid is patent again. Blood loss approx. 1,800 ml; 3 transfusions. No complications.




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New possibilities of controlled hypotension in neurosurgery.

The position of controlled hypotension in neurosurgery is reviewed including both the new and old techniques and the drugs used. A special emphasis is...
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