Cardiovascular disturbances caused by extradural ... - Semantic Scholar

British Journal of Anaesthesia 1998; 80: 599–601

Cardiovascular disturbances caused by extradural negative pressure drainage systems after intracranial surgery J. HERNÁNDEZ-PALAZÓN, J. A. TORTOSA, S. SÁNCHEZ-BAUTISTA, J. F. MARTÍNEZ-LAGE AND D. PÉREZ-FLORES

Summary Extradural drainage systems connected to a vacuum device for preventing postoperative haematoma formation are often used in neurosurgical practice. Cardiovascular complications, including bradycardia or low arterial pressure caused by intracranial hypotension, have been described associated with their use. We have investigated the relationship between the negative pressure applied to extradural drainage systems and intracranial pressure (ICP), and analysed the effects of negative pressure of the drains on systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures and on heart rate (HR). We studied prospectively 15 patients undergoing neurosurgery for supratentorial tumours or aneurysms. Transient decreases in ICP (P:0.001) and HR (P:0.001), with no clinical effects, were observed after connecting the vacuum device to the drain. There were no significant changes in SAP, DAP or MAP. (Br. J. Anaesth. 1998; 80: 599–601) Keywords: equipment, extradural drainage systems; heart, heart rate; surgery, neurological; cardiovascular system, effects

Increased intracranial pressure (ICP) can cause bradycardia and hypertension as a result of the stimulus of pressure or stretch, or both, of the brainstem, referred to as Cushing’s response.1 2 However, haemodynamic changes associated with intracranial hypotension have seldom been described. Most reports are based on clinical observations. Many neurosurgical procedures, such as surgery for brain tumours and haematomas, require the use of extradural or epicranial drains, which are frequently connected to a vacuum device for preventing haematoma formation or drain obstruction. Severe cardiovascular disorders (bradycardia, asystole or arterial hypotension) related to their use have been published.3 4 The aim of our study was to investigate the effect on ICP of the negative pressure achieved by an extradural drainage system and its consequences on heart rate (HR), systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures.

Patients and methods We studied 15 consecutive patients, aged 28–65 yr, ASA I–II, undergoing elective supratentorial tumour and aneurysm surgery. The study was approved by

the Institutional Human Ethics Committee and patient consent was obtained. On arrival in the operating room, patients were premedicated with midazolam 0.02–0.03 mg kg91 i.v. Anaesthesia was induced with thiopental 4–6 mg kg91, fentanyl 3–4 ␮g kg91 and lidocaine 1.5 mg kg91. Vecuronium (up to 0.2 mg kg91) was administered to aid tracheal intubation. Anaesthesia was maintained with isoflurane (0.2–0.6 % end-tidal concentration) and 60–70% nitrous oxide in oxygen, and fentanyl 1–2 ␮g kg91 h91. Neuromuscular block was produced with vecuronium 0.08–0.1 mg kg91 h91. Controlled mechanical ventilation (Servo 900 C ventilator) was adjusted to maintain end-tidal carbon dioxide partial pressure ( P E ′CO2) at 3.7–4.3 kPa. Before induction of anaesthesia, we monitored invasively radial arterial pressure, HR, electrocardiogram (leads II and V5) and arterial haemoglobin oxygen saturation (SpO2 ) using a Siemens Sirecust 730 monitor. P E ′CO2 was measured with an Engström Eliza carbon dioxide analyser, and neuromuscular function was monitored with a Microstin Plus peripheral nerve stimulator. After induction of anaesthesia, we inserted a nasopharyngeal thermometer, oesophageal stethoscope and central venous catheter. The skin was infiltrated with 0.5% bupivacaine before the start of surgery. Mannitol 0.5 g kg91, sometimes associated with a loop diuretic, was administered. MAP was 80–110 mm Hg during surgery. After tumour resection or aneurysm clipping, and before totally closing the dura mater, the neurosurgeon placed a subdural fibreoptic transducer attached to a Camino monitor (Camino 420 OLM) for continuous recording of ICP. ICP recording was started at the end of surgery. In all patients the dura mater was sutured in a watertight manner, and when there remained a space between the brain and dura mater, it was filled with saline solution infused without applying pressure. Before bone flap replacement, an extradural drain was positioned in the extradural space, as far as JOAQUÍN HERNÁNDEZ-PALAZÓN, MD, PHD, JOSÉ A. TORTOSA*, MD, PHD, SUSANA SÁNCHEZ-BAUTISTA, MD (Department of Anaesthesia); JUAN F. MARTINEZ-LAGE, MD, (Department of Neurosurgery); Hospital Universitario “Virgen de la Arrixaca”, Murcia, Spain. DOMINGO PÉREZ-ZLORES, PHD, Department of Biostatistics, School of Medicine, University of Murcia, Murcia, Spain. Accepted for publication: December 19, 1997. *Address for correspondence: C/Ricardo Gil 26, 2⬚ B, E- 30002 Murcia, Spain.

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possible from the ICP sensor. The drain was then connected to a suction system (Red-O-Pack, Vygon, France) to which subatmospheric vacuum pressure had been applied. The drainage system was stabilized at the end of the procedure and maintained for the first 24 h, as indicated by the surgeon. Negative pressure was applied only after surgical closure and wound dressing. The pressure applied to the vacuum device was measured by a manometer attached to the vacuum system. ICP and haemodynamic variables (SAP, DAP, MAP and HR) were recorded continuously at the end of operation, before connecting the drain to the vacuum system, after connection, while the patient was still anaesthetized, in the supine position, and with slight elevation of the head (10⬚). Peak values of these variables, and time after vacuum application were recorded. Duration of these changes was also noted. For statistical analysis, we used the logtransformation and the Shapiro–Wilks test to study the normality of the data. This demonstrated a nonnormal distribution. Data were analysed using the non-parametric Wilcoxon test for paired samples. We also used covariance analysis (ANCOVA) with repeated measures and multiple regression analysis to evaluate the relation between decrease in HR (∆HR) and decrease in ICP (∆ICP) after applying negative pressure to the extradural drainage system. Differences were considered statistically significant when P:0.05.

Results Patient data (age, sex, weight), duration of surgery, duration of anaesthesia, negative pressure values in the vacuum system and type of surgical procedure are presented in table 1. A decrease in SAP, MAP and an increase in DAP with regard to baseline values was observed immediately after application of the vacuum to the drainage system, but these differences were not significant (table 2). There were significant decreases in HR and ICP (P:0.001) after applying negative pressure Table 1 Patient characteristics (median (range)) n Age (yr) Sex (M:F) Weight (kg) Negative pressure (cm H2O) Duration of anaesthesia (min) Duration of surgery (min) Surgican procedure (excision of tumour:aneurysm clipping)

15 56 (28–65) 9:6 68 (57–86) 75 (65–80) 315 (240–450) 210 (150–360) 8:7

Table 2 Systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures, and heart rate (HR) and intracranial pressure (ICP) before and after placement of an extradural drain connected to a vacuum system (median (range))

SAP (mm Hg) MAP (mm Hg) DAP (mm Hg) HR (beat min91) ICP (mm Hg)

Before negative pressure

Immediately after connection of vacuum system

P

124 (107–145) 91 (76–101) 65 (60–78) 65 (55–90) 4 (1–10)

122 (107–142) 90 (75–102) 71 (60–82) 58 (51–87) 95 (918 to 92)

ns ns ns :0.001 :0.001

(table 2). After application of the vacuum system, ICP decreased to subatmospheric values in all patients. Mean intervals from application of the vacuum system to measurement of the lower values of ICP and HR were 70 (range 4–175) and 21 (8–91) s, respectively. The changes in HR and ICP were temporary and returned to those obtained before application of the negative pressure at mean times of 32 (18–75) s and 97 (20–242) min, respectively. We found no correlation between the decrease in HR (∆HR) and decrease in ICP (∆ICP) after application of negative pressure to the extradural drainage system.

Discussion In this study, placement of an extradural drain connected to a vacuum system at the end of intracranial surgery produced a sudden decrease in ICP that reached subatmospheric values in all patients. This sudden reduction in ICP was caused by transmission of negative pressure from the area (extradural or epicranial space) where the drain was located to the subdural space. Severe decreases in ICP may cause a rostral shift of the brain which is reversed when ICP returns to its previous values. Physical properties of brain tissues may preclude this shift, even during suction.4–8 In our study, a significant decrease in HR without changes in arterial pressure was observed immediately after connecting the vacuum system and before reaching the peak decrease in ICP. However, there was a rapid return to pre-suction values. These data are in agreement with those of Gilsanz and colleagues7 who observed a significant decrease in HR 3 min after connecting the vacuum system to the epicranial drain. However, in our study, the effect of the negative pressure on ICP and HR was more immediate. Several reports have described severe bradycardia or arterial hypotension, or both, after connection of negative suction pressure to extradural6 9 or epicranial5 10 drains after craniotomy. These haemodynamic changes were similar to those observed when ICP suddenly decreased after decompression of hydrocephalic ventricles.11 12 Rapid removal of cerebrospinal fluid (CSF) in patients with obstructive hydrocephalus or intracranial application of negative pressure via an extradural or epicranial drain, may lead to a sudden state of intracranial hypotension resulting in a rostral movement of the brain or brainstem nuclei responsible for the changes in cardiac rhythm or arterial hypotension, or both.4 5 7 12 13 Reduction in HR secondary to a sudden decrease in ICP may be caused by a mechanism similar to Cushing’s response to intracranial hypertension.9 Several authors1 2 have demonstrated that the haemodynamic features of Cushing’s response can be produced by electrical stimulation or distension of tissues within a thin strip of brain along the floor of the fourth ventricle in the rostral medulla and caudal pons, the efferent limb of the bradycardic response being the vagus nerve. The observed cardiovascular disorders reverse on releasing the negative pressure or by filling the ventricles with saline solution after decompression in hydrophalus.5 6 9 11 In our study, we observed no

Cardiovascular disturbances and drainage systems in neurosurgery correlation between HR and ICP values, which would indicate the contribution of other factors in the decrease in HR. Application of a strong negative pressure to the drainage system, reduction of the brain bulk at the end of craniotomy (provoked by the use of mannitol, hyperventilation, CSF leakage during surgery and tumour resection), administration of ␤ blockers and stretching on the dura mater may lead to important haemodynamic disturbances with subsequent clinical consequences.5 10 14 15 In our study, the use of an extradural drain connected to a vacuum system after craniotomy had no clinically significant adverse effects. However, there exists the possibility of an important decrease in ICP which could provoke severe cardiovascular consequences. Therefore, haemodynamic variables must be monitored closely and controlled at the time of applying negative pressure to the drain. If severe bradycardia occurs, it should be managed promptly with anticholinergic agents and closure of the drainage system.

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