British Journal of Anaesthesia, 2003, Vol. 90, No. 5 694-698
© 2003 The Board of Management and Trustees of the British Journal of Anaesthesia
Case Reports |
Detection of cerebral hypoperfusion with bispectral index during paediatric cardiac surgery
Departments of 1 Anaesthesiology and 2 Cardiovascular Surgery, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
Corresponding author. E-mail: hayashida-todai@umin.ac.jp
Accepted for publication: January 13, 2003
 |
Abstract |
|---|
 Top Abstract IntroductionCase reportsDiscussionReferences |
|---|
Background. The bispectral index (BIS) may indicate changes in cerebral activity when the cerebral circulation is affected by acute hypotension.
Methods. We measured BIS and cerebral haemoglobin saturation (SrO2) by near-infrared spectroscopy in 10 children undergoing cardiac surgery.
Results. We noted 14 episodes of simultaneous decreases in SrO2 and BIS during acute hypotension in five children. An acute decrease in BIS, which coincided with a decrease in SrO2 suggesting a reduction in cerebral blood flow, was associated with acute slowing of the raw EEG waveforms.
Conclusions. Our findings suggest that an acute decrease in BIS during acute hypotension indicates cerebral hypoperfusion, and that cerebral hypoperfusion caused by hypotension may occur frequently during paediatric cardiac surgery.
Br J Anaesth 2003; 90: 694–8
Keywords: monitoring, bispectral index; monitoring, electroencephalography; surgery, paediatric; surgery, cardiovascular
|
Introduction |
|---|
|
TopAbstractIntroductionCase reportsDiscussionReferences |
|---|
Recent studies show that the bispectral index (BIS) is a useful monitor of hypnotic state during general anaesthesia in adults1 and also in children.2–4 We have measured BIS in children undergoing non-complex cardiac surgery, whose tracheas were to be extubated immediately after surgery and in whom intraoperative awareness was of some concern. We report our initial experience with BIS monitoring in the first 10 children.
|
Case reports |
|---|
|
TopAbstractIntroductionCase reportsDiscussionReferences |
|---|
After institutional approval and informed consent, we applied BIS monitoring (A-1050, Aspect Medical Systems, Natick, MA, USA) to 10 consecutive children aged 2–11 yr undergoing corrective surgery for non-cyanotic heart disease (Table 1). We also measured regional cerebral haemoglobin oxygen saturation (SrO2) by near-infrared spectroscopy (NIRS) (PSA-3N, Biomedical Science, Kanazawa, Japan). Anaesthesia was maintained with sevoflurane in oxygen-enriched air and intermittent doses of fentanyl and midazolam (Table 1). The priming solution for the cardiopulmonary bypass (CPB) circuit consisted of balanced salt solution with the addition of mannitol and albumin. Blood was not added to the system. Mild or moderate hypothermia was induced during CPB. After surgical correction, dobutamine and dopamine were infused i.v. to facilitate weaning from CPB.
|
In five children aged 3 yr or less, and not in five children older than 3 yr, we noted unusual decreases in BIS as follows (Table 1).
Case 4: at the start of, during and immediately after CPB, four episodes when SrO2 and BIS decreased at the same time during acute hypotension (Fig. 1);
|
Case 5: before CPB, two episodes when SrO2 and BIS decreased at the same time as blood pressure decreased (Fig. 2);
|
Case 6: at the start of CPB, both SrO2 and BIS decreased acutely with hypotension (Fig. 3);
|
Case 7: at the start of and during CPB, three episodes of acute reduction in both SrO2 and BIS immediately after acute hypotension (Fig. 4);
|
Case 10: at the beginning of and during CPB, four episodes of acute reduction in SrO2 and BIS at the same time as hypotension (Fig. 5).
|
Acute decreases in BIS were associated with acute slowing of the raw EEG frequency (Figs 4 and 5). All episodes of simultaneous decreases in SrO2 and BIS were associated with clinically important acute hypotension. There was no change in anaesthetic administration at these times. Reductions in BIS lasted for no longer than 3 min even when arterial pressure did not return to a normal level (Figs 1 and 4). In five children aged 3 yr or less in whom decreases in BIS occurred at the same time as acute hypotension, SrO2 tended to change in parallel with changing arterial pressure throughout surgery (Figs 1–5). In five children older than 3 yr, a hypotension-induced decrease in BIS did not occur while SrO2 remained almost constant throughout surgery, although BIS decreased only slightly and transiently during acute hypotension. We did not find neurological deficits in any of the patients after surgery.
|
Discussion |
|---|
|
TopAbstractIntroductionCase reportsDiscussionReferences |
|---|
We used BIS monitoring in children undergoing cardiac surgery to assess possible intraoperative awareness with our anaesthetic methods. We were struck by unusual decreases in BIS rather than increases in BIS that might suggest light anaesthesia.
In five of the 10 children, we found simultaneous acute decreases in SrO2 and BIS during acute hypotension. An acute decrease in SrO2 suggests an acute reduction in cerebral blood flow (CBF) or cerebral oxygen supply unless cerebral oxygen consumption changes acutely.5 Acute decrease in BIS in our patients occurred with acute slowing of the EEG. The acute EEG slowing is a sign of cerebral hypoperfusion, and can be detected within seconds of severe hypotension, cardiac arrest or carotid occlusion using other processed EEG methods.6–10 Our findings suggest that if a change in BIS is not drug induced, an acute decrease in BIS indicates cerebral hypoperfusion, particularly when it accompanies acute hypotension and a decrease in SrO2.
A decrease in jugular venous haemoglobin saturation (SjO2) to less than 50% is generally considered to indicate cerebral hypoperfusion.11 Values of SrO2 remained above 60% in most of our patients, however, even when cerebral hypoperfusion was indicated by acute EEG slowing or a decrease in BIS. The relatively high SrO2 values during cerebral hypoperfusion might result in part from the lack of calibration of the NIRS oximeter in children, since an absolute value of SrO2 can be obtained only after calibration based on some assumptions. The clinical value of an NIRS oximeter is thus limited to tracking trends of SrO2.12 13 In addition, SrO2 may remain higher than SjO2 because SrO2 represents the weighted average of haemoglobin saturation of arterial, capillary and venous blood within a volume of tissue whereas SjO2 indicates venous haemoglobin saturation.13 14 For example, even when SjO2 is 50%, SrO2 can be 62.5% if SaO2 is nearly 100%, assuming that blood in the cerebral vasculature is three-quarters in the venous bed and one-quarter in the arterial bed (SrO2=0.75xSjO2+ 0.25xSaO2).12 For these reasons, cerebral hypoxia may be present when the SrO2 value is relatively greater than the SjO2 value.
Cerebral hypoperfusion indicated by acute EEG slowing or an acute BIS reduction occurred most commonly at the start of CPB. Acute haemodilution might contribute to development of cerebral perfusion at this time point because of reduced arterial pressure and reduced oxygen carrying capacity associated with haemodilution. More directly, bloodless prime being flushed through the brain could decrease electrical activity at the onset of CPB.
Cerebral hypoperfusion caused by acute hypotension occurred often in the five children aged 3 yr or younger but not in the five older children. Only in the younger children did SrO2 change in parallel with changing arterial pressure throughout surgery, suggesting that CBF depended on arterial pressure in these younger children. Although data regarding the development of cerebral autoregulation in humans are lacking,15 our findings suggest that cerebral autoregulation is immature during infancy. With an abrupt reduction in cerebral perfusion pressure, blood flow will decrease for a brief period (1–2 min) before autoregulation restores CBF.16 The immature autoregulatory system may take more time to restore CBF, and thus a decrease in CBF that is long and severe enough to cause decreased cerebral electrical activity can occur more easily in younger children. Even in younger children, however, SrO2 tended to return towards a normal level, and decreases in BIS lasted no longer than 3 min, even when arterial pressure remained at a reduced level. Therefore, it was likely that cerebral autoregulation acted slowly to restore CBF and EEG during persistent hypotension in the younger children.
One case report described an acute profound reduction in BIS following hypovolaemic cardiac arrest during adult cardiac surgery.17 We found that in children undergoing cardiac surgery, cerebral hypoperfusion can occur not only following severe haemodynamic changes such as cardiac arrest but also following less severe changes in arterial pressure such as hypotension at the onset of CPB.
We cannot determine the saturation level at which cerebral ischaemia will occur with an NIRS oximeter alone.13 14 By combining SrO2 and BIS, we can establish if a reduction of CBF indicated by a decrease of SrO2 is sufficient to slow the EEG by following BIS. Conversely, we can determine whether a decreased BIS value is caused by decreased CBF rather than other causes (e.g. deepened anaesthesia or hypothermia) by noticing changes in SrO2.
The manufacturer of the device notes clearly that BIS is not intended as a monitor of ischaemia. Further studies are required to assess the adequacy of such use.17 In our patients, however, development of and recovery from cerebral hypoperfusion could be conveniently monitored with the BIS EEG monitor. This simple-to-use monitor of brain function may indicate hypoxia and recovery of cerebral electrical activity in response to circulatory changes during anaesthesia and surgery, especially when used in combination with an NIRS oximeter.
|
References |
|---|
|
TopAbstractIntroductionCase reportsDiscussionReferences |
|---|
1 Rampil IJ. A primer for EEG signal processing in anesthesia. Anesthesiology 1998; 89: 980–1002[CrossRef][Web of Science][Medline]
2 Watcha MF, Galinkin J, Fazi LM. Bispectral index (BIS) EEG monitoring in children. Anesthesiology 1999; 91: A1266
3 Denman WT, Swanson EL, Roscow D, Ezbicki K, Connors PD, Rosow CE. Pediatric evaluation of the bispectral index (BIS) monitor and correlation of BIS with end-tidal sevoflurane concentration in infants and children. Anesth Analg 2000; 90: 872–7
4 Bannister CF, Brosius KK, Sigl JC, Meyer BJ, Sebel PS. The effect of Bispectral Index monitoring on anesthetic use and recovery in children anesthetized with sevoflurane in nitrous oxide. Anesth Analg 2001; 92: 877–81
5 Kurth CD, Steven JM, Nicolson SC. Cerebral oxygenation during pediatric cardiac surgery using deep hypothermic circulatory arrest. Anesthesiology 1995; 82: 74–82[CrossRef][Web of Science][Medline]
6 Stockard JJ, Bickford RG, Schauble JF. Pressure-dependent cerebral ischemia during cardiopulmonary bypass. Neurology 1973; 23: 521–9
7 Stockard JJ, Bickford RG, Myers RR, et al. Hypotension-induced changes in cerebral function during cardiac surgery. Stroke 1974; 5: 730–45
8 Rampil IJ, Holzer JA, Quest DO, et al. Prognostic value of computerized EEG analysis during carotid endarterectomy. Anesth Analg 1983; 62: 186–92
9 Levy WJ. Quantitative analysis of EEG changes during hypothermia. Anesthesiology 1984; 60: 291–7[CrossRef][Web of Science][Medline]
10 Smith DS, Levy W, Maris M, et al. Reperfusion hyperoxia in brain after circulatory arrest in humans. Anesthesiology 1990; 73: 12–19[Web of Science][Medline]
11 Drummond JC, Patel PM. Neurosurgical anesthesia. In: Miller RD, ed. Anesthesia. Philadelphia: Churchill Livingstone, 2000; 1895–1933
12 Henson LC, Calalang C, Temp JA, et al. Accuracy of a cerebral oximeter in healthy volunteers under conditions of isocapnic hypoxia. Anesthesiology 1998; 88: 58–65[Web of Science][Medline]
13 McCulloch T, Lam AM. Specialized neurophysiologic monitoring. In: Lake CL, Hines RL, Blitt CD, eds. Clinical Monitoring. Philadelphia: W.B. Saunders, 2001; 132–45
14 Tremper KK, Baker SJ. Monitoring of oxygen. In: Lake CL, Hines RL, Blitt CD, eds. Clinical Monitoring. Philadelphia: W.B. Saunders, 2001; 315–34
15 Bissonnette B, Armstrong DC, Rutka JT. Pediatric neuroanesthesia. In: Albin MS, ed. Textbook of Neuroanesthesia. New York: McGraw-Hill, 1997; 1177–240
16 Michenfelder JD. Anesthesia and the Brain. New York: Churchill Livingstone, 1988; 3–21
17 England MR. The changes in Bispectral Index during a hypovolemic cardiac arrest. Anesthesiology 1999; 91: 1947–9[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  C. S. Leggat and G. W. Fischer Early Detection of an Acute Cerebral Event During Cardiopulmonary Bypass Using a Bispectral Index Monitor Seminars in Cardiothoracic and Vascular Anesthesia, March 1, 2008; 12(1): 80 - 82. [Abstract] [PDF]
|
|
|
|
 |
|
 N. Ohshima, M. Chinzei, K. Mizuno, M. Hayashida, T. Kitamura, H. Shibuya, and K. Hanaoka Transient decreases in Bispectral Index without associated changes in the level of consciousness during photic stimulation in an epileptic patient Br. J. Anaesth., January 1, 2007; 98(1): 100 - 104. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Deogaonkar, R. Vivar, R. E. Bullock, K. Price, I. Chambers, and A. D. Mendelow Bispectral index monitoring may not reliably indicate cerebral ischaemia during awake carotid endarterectomy Br. J. Anaesth., June 1, 2005; 94(6): 800 - 804. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. M. Hemmerling, J.-F. Olivier, F. Basile, N. Le, and I. Prieto Bispectral Index as an Indicator of Cerebral Hypoperfusion During Off-Pump Coronary Artery Bypass Grafting Anesth. Analg., February 1, 2005; 100(2): 354 - 356. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Morimoto, Y. Monden, K. Ohtake, T. Sakabe, and S. Hagihira The Detection of Cerebral Hypoperfusion with Bispectral Index Monitoring During General Anesthesia Anesth. Analg., January 1, 2005; 100(1): 158 - 161. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Chinzei, S. Sawamura, M. Hayashida, T. Kitamura, H. Tamai, and K. Hanaoka Change in Bispectral Index During Epileptiform Electrical Activity Under Sevoflurane Anesthesia in a Patient with Epilepsy Anesth. Analg., June 1, 2004; 98(6): 1734 - 1736. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Hayashida, N. Kin, T. Tomioka, R. Orii, H. Sekiyama, H. Usui, M. Chinzei, and K. Hanaoka Cerebral ischaemia during cardiac surgery in children detected by combined monitoring of BIS and near-infrared spectroscopy Br. J. Anaesth., May 1, 2004; 92(5): 662 - 669. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Bainbridge, J. Murkin, C. Calaritis, and A. Menkis Aortic Dissection in a Patient with a Previous Ascending Aortic Dissection and Repair: The Role of New Monitoring Devices in the High-Risk Patient Seminars in Cardiothoracic and Vascular Anesthesia, March 1, 2004; 8(1): 3 - 7. [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||