ISSN 2466-488X (Online) doi:10.5937/sjait1606161J

Revijalni članak Review article

HOW DEEP IS YOUR LOVE: AWARENESS HOW DEEP IS YOUR LOVE: MONITORING DURING GENERAL MONITORING BUDNOSTI TOKOM ANESTEZIJE

Radmilo Janković1,2, Danica Marković1, Biljana Stošić1,2 Radmilo Janković1,2, Danica Marković1, Biljana Stošić1,2

1Center for and Reanimatology, ClinicalCenter of 1Centar za anesteziologiju i reanimatologiju, Klinički centar u Nišu, Niš, Serbia Niš, Srbija 2Department for Anesthesiology and Intensive Care,School of Me- 2Katedra za anesteziologiju i intenzivnu negu, Medicinski fakultet, dicine, University of Niš, Serbia Univerzitet u Nišu, Niš, Srbija

Abstract Sažetak

The 5th National Audit Project (NAP5) has established Istraživanja u okviru The 5th National Audit Project that the incidence of accidental awareness during general (NAP5) su utvrdila da se prisustvo slučajne svesti tokom anaesthesia is about 1 in 15414 general anesthesia. In to- opšte anestezije dešava jednom u 15414 slučajeva. Ukup- tal, about two-thirds of accidental awareness during gen- no oko dve trećine slučajnih svesti tokom opšte anestezije eral anaesthesia happened during the so-called „dynamic“ se dešavaju tokom takozvanih dinamičnih faza anestezije. phase of anesthesia. The stages of consciousness are often Prisustvo svesti obično jako kratko traje, što ukazuje na very short and that implies that the used monitoring must to da monitoring mora biti osposobljen da detektuje čak i be able to detect even a short phase of consciousness. Ad- kratke faze svesti. Administracija neuromišićnih blokatora ministration of neuromuscular blockators makes monitor- otežava monitoring svesti, te se najpouzdanijim monito- ing of consciousness difficult, therefore currently the most ringom smatraju: izolovana tehnika nadlaktice, BIS mo- reliable methods of monitoring are: IFT, BIS monitoring nitoring i održavanje ETAG iznad 0,7 MAC. Svakako ni and maintenance of ETAG > 0.7 MAC. Certainly, none of jedna od ovih metoda se ne sme koristiti izolovano od is- these methods can be used independently from the experi- kustva anesteziologa i kliničkih metoda za procenu stanja enced anesthesiologists and clinical methods for assessing svesti tokom opšte anestezije. accidental awareness during .

Key words: awareness; monitoring; general; anes- Ključne reči: budnost; monitoring; opšta anestezija thesia Introduction mely short, therefore the used monitoring must be able to detect short phases of consciousness5. ccording to some studies, the incidence of Presence of awareness is classified by authors Aaccidental awareness during general anesthe- Griffith and Jones as follows: presence of aware- sia (AAGA) showed an extremely high frequency, ness with complaints of pain observations, the even 1–2 per 1,000 general anesthesia, while some presence of consciousness with a clear reply but other studies had suggested a much lower inciden- absence of pain, the presence of consciousness or ce of AAGA, about 1 in 14500 of general anesthe- „alertness“ (the ability to respond to simple verbal sia1–4. Pandit et al. under the 5th National Audit commands), the absence of a clear answer and pain Project (NAP5) found in 2011. that the number of but possible presence of memory, lack of a clear AAGA is about 1 in 15414 of general anesthesia. response but with the presence of memory about Two thirds of AAGA occurred during the so-called intraoperative events and lack of awareness6,7. „dynamic“ phase of anesthesia, especially during or Three main risk factors are described: trauma, immediately after induction of anesthesia. The sta- cesarean section, and cardiovascular . In ges of consciousness during anesthesia were extre- the case of these anesthesia is intention- Autor za korespondenciju: Radmilo Janković, Klinički centar u Corresponding author: Radmilo Janković, Clinical center in Nišu, Bulevar dr Zorana Đinđića 48, 18000 Niš, Srbija, Telefon: Niš, Bulevar dr Zorana Đinđića 48, 18000 Niš, Serbia, Telephone: 065/3349729, E-mail: [email protected] 065/3349729, E-mail: [email protected] 162 SJAIT 2016/5-6 ally maintained shallow in order to avoid serious lash reflex, perspiration, pupil response or change cardiovascular or birth defects. About of its diameter and watery eyes7,8. The most com- 95% of AAGA cases are associated with human monly used scoring represents PRST or Evans’s mistake or failure of anesthesiological device or index, which includes P (systolic pressure), failure of monitoring devices8. R ( rate), S (sweating) and T (tears)7,13. Index Ideal anesthesia is achieved by using such score ranges from 0 to 8, however, it rarely exceeds as hypnotics, , neuromuscular relaxants the mean value, which indicates the deficinency of and implies the absence of consciousness, antinocic- the scoring system in daily practice. It is believed eption and immobility. Studies have clearly demon- that monitoring of and strated that some patients require significantly with assessment of pupil size is the most useful for higher doses of medications in order to achieve and the assessment of adequate analgesia and depth of 8 maintain an adequate level of anesthesia . anesthesia. High frequency fluctuations in heart Intraoperative awareness with clear motor re- rate i.e. changes in heart rate with the frequency sponse is associated with post-traumatic dis- of ventilation (respiratory sinus arrhythmia, RSA) 9 order, whose incidence of about 0.15% . In order to reflect the level anesthesia depth. Such monitor- reduce the incidence of awareness with the patients ing is useful but depends on the extent to which response, there are discussions in scientific circles the autonomic nervous system of the patient is which monitoring should be used during inhala- preserved as well as on the health of the patients tional anesthesia. Recommendations regarding cardiovascular system. Beta blockers, conduction appropriate monitoring are more and more imple- abnormalities, autonomic neuropathy and mented in national clinical practice guidelines in may influence this type of monitoring7,8,14. order to improve anesthesia, reduce the amount of Standard monitoring includes electrocardio- anesthetic that is used in a patient, reduce costs, gram, blood pressure, heart rate, and improve postoperative recovery and reduce the in- end tidal anesthetic analyzer. There are no major cidence of awareness10. The level of awareness is mostly determined by clinical trials which determine connection between standard clinical techniques and standard monitor- the degree in which a person responds or not to 8 the growing stimulus. Failure of verbal or motor ing with the incidence of AAGA occurrence . response after the administration of hypnotics or narcotics (without administration of muscle relax- Most frequently used aaga monitoring ant) even after painful surgical stimulus is consid- ered to be a patient in a sufficiently deep anesthe- In order to minimize intraoperative awareness sia11. The fact is that the administration of neuro- of the patient, anesthetist has three available op- muscular blockers prevents the motor response of tions: IFT, BIS monitoring and maintenance of patients and therefore makes experienced anes- ETAG > 0.7 MAC12. thesiologists assessment difficult of whether the End-tidal anesthetic gas monitoring (ETAG) patient is conscious or not. A large number of re- Anesthetic agents are titrated by their mini- searchers believe that even anesthesia guided with mum alveolar concentration (MAC) and the he- appropriate monitoring does not provide complete modynamic response. MAC is defined as the anes- certainty that the patient will lose consciousness thetic concentration at 1 atmosphere which causes during surgery10. In such cases, the determination immobility in 50% of patients exposed to surgical of the consciousness level is based on the anesthe- stimulation. However, it turned out that MAC has siologists experience and on the use of anesthesia a poor correlation with the degree of hypnosis12. depth monitoring such as isolated forearm tech- ETAG monitoring alarms represent a reliable nique (IFT) or processed EEG monitor (pEEG)11,12. way of securing sufficient quantities of volatile anesthetics for a specific patient. Audible signals Clinical techniques and standard monitoring are heard if the minimum alveolar concentra- of aaga tion reaches < 0.7 or > 1.31. Several studies have concluded that BIS monitoring is not better than Standard clinical methods for AAGA assessing ETAG monitoring in the prevention of patient are: response to the given commands, gestures, eye- awareness during anesthesia1,9,10. HOW DEEP IS YOUR LOVE: AWARENESS MONITORING DURING GENERAL ANESTHESIA 163 Isolated forearm technique (IFT) too much time and distracts attention from other monitoring19. It is evident that IFT method as the In a performance of the isolated forearm tech- monitoring technique is used by only 14 of over nique (IFT) monitoring Tourniquet is placed on 8,000 clinicians in England20. one forearm and inflates above arterial pressure Reported cases of wakefulness during the use of before neuromuscular relaxant is injected into one IFT techniques are rare, except for a few report- of the peripheral veins. For this reason neuromus- ed cases of discomfort. Studies which used an IFT cular blocking agent does not reach neuromuscular method showed that many patients may be aware junctions located below the Tourniquet and there- and able to respond to commands and not to have fore reflex responses or responses to commands post-operative memories10,21. issued by the anesthesiologist can be observed10,15. Of course, extensive studies are needed in order IFT is considered in today’s practice to be the gold to determine the value of IFT monitoring in every- standard for awareness monitoring in the presence day practice. of neuromuscular blockade16. It is the fact that the use of IFT showed that inadequate levels of anesthe- Monitoring of brain electrical activity sia has not been accompanied by heart rate change, sweating, and the production of tears in practice17. Devices designed to monitor electrical activity There are a number of reasons why IFT mon- of the brain are mainly based on information ob- itoring cant be effective in everyday practice. For tained from the electrodes on the forehead of the example, anesthetic can occasionally cause cataton- patient. After amplification and conversion of EEG ic „locked“ status (catatonic locked-in state) in the signals an index is obtained and it generally ranges anesthetized but partially conscious patients12,18. from 0 to 100. This index reflects the state of mind, Also, there may be a number of technical problems ie the state of vigilance, , light anesthesia such as cuff failure, unexpectedly long clearance of and deep anesthesia7,8. muscle relaxants, limb ischemia, etc.18. The nega- One of the oldest and most basic monitoring tive side of this technique is also the so-called state of this type is the monitoring of spontaneous EEG of dysanesthesia, in which the patient’s perception activity with 19 electrodes. However, besides it is partly separated from the feeling, so the patient requiring a longer time of placement and taking responds to commands but does not move his hand longer to start monitoring, it is evident that dif- spontaneously during surgery19. Some clinicians ferent anesthetics give a different EEG picture and believe that the motor response during the oper- therefore the interpretation is difficult. Also, var- ation is the late sign of awareness and that IFT has ious events (, hypercarbia, etc.) have no importance in the prevention of consciousness8. the consequence of EEG changes22. Similar to this Russel has explained in his editorial some of monitoring is the compressed spectral analysis the misconceptions associated with this method (CSA). However, in addition to other numerous after many years of experience with the use of IFT. deficiencies there is also the fact that it cant be used According to experience, it is possible to keep the independently ie. without the active monitoring of inflated Turniquet up to 40 minutes without the clinical parameters7,8,23. Some other possible solu- appearance of ischemic , even an easy tions for monitoring the electrical activity of the monitoring of neuromuscular integrity through a brain are: EEG with compressed spectral analysis, peripheral nerve stimulator is recommended. He cerebral function monitor (CFM), cerebral func- also believes that the ischemic nerve block recovers tion analysis monitor (CFAM), entropy (which a few minutes after the release of Tourniquet. Use processes EEG signals and FEMG signals with of almost all muscle relaxants (curare, alcuronium, the help of the Entropy algorithm), Cerebral state atracurium, vecuronium, lower doses of pancuro- monitor / Cerebral state index (CSI), etc.7, 8, 23, 24 nium, 0.05 mg/kg) was not accompanied with pa- ralysis of the limbs after Tourniquet release15. Processed EEG monitoring Not too many anesthesiologist use the IFT technique since they believe that this technique Propofol, thiopentone and inhaled anesthetics is difficult, and that this is a technique that takes produce similar EEG changes as a result of en- 164 SJAIT 2016/5-6 hancement of their concentration in the brain tis- has been observed when the BIS ranged 46–50 and sue and deepening of the sedation and anesthesia 56–6010. depth. With the increase of anesthesia depth the Meta-analyzes have pointed to the fact that the following changes in the EEG signal happen: ini- BIS monitor can greatly reduce the use of anes- tial increase of high-frequency components, then thetics, reduce the time to extubation, to fast- increase of the low frequency components, in- er recovery from anesthesia as well as reduce the crease of the amplitude of EEG waves, increase of incidence of nausea and vomiting and reduce the the regularity of the EEG signal, burst suppression level of intraoperative awareness9,25,27. However, in deep anesthesia and isoelectric „straight line“ in Mashour et al have showed in their study that the very deep anesthesia. use of the BIS monitor is not associated with a re- The (BIS) monitor (Covidien, duction in recovery time, as well as with a reduced Boulder, CO) keeps track of frontal EEG channel incidence of nausea and vomiting9. with the aim to calculate the number between 100 Zand et al have pointed out that BIS is not a reli- (alertness) and 0 (not detectable brain activity) and able monitor of depth of anesthesia when it comes therefore measure the patient’s level of conscious- to caesarean section and sevoflurane anesthesia. It ness9. BIS index represents an algorithm which takes less than recommended levels of BIS to avoid converts the single-channel EEG into the index of IFT responses during laryngoscopy, intubation the hypnosis degree. There are several intraoper- and skin incision16. ative events that are not related to the amount of A long period of deep hypnosis (BIS < 40) can anesthetics and which cause a rapid change in BIS increase postoperative morbidity and mortality. values, such as: brain ischemia, air embolus, un- Also, extended deep hypnosis may have a short- recognized hemorrhage, etc.7,8. The values of BIS term negative impact on recovery from anesthesia, index 60–80 indicate that the patient can more eas- as well as cause postoperative delirium and cogni- ily respond to mechanical stimulation, while the tive disorders. It can disrupt the immune system value of 45–60 is associated with a low probability and accelerate the emergence of infections and of a clear answer. BIS level below 45 is associated tumor growth. It is therefore of great importance with the state of deep hypnosis. Russel et al and to know the BIS values in​​ certain MAC concentra- Zand et al have showed that the BIS value below 60 tions of inhaled anesthetics. Kim et al. have com- does not mean a little chance of vigilance without pared BIS profiles of the study participants with an answer when compared to the IFT results9,10,15,16. the equipotent doses of isoflurane, sevoflurane and Cochrane review declared that BIS-guided desflurane (1MAC) during the maintenance phase anesthesia can reduce the risk of intraoperative of anesthesia. The duration of deep hypnosis (BIS awareness in surgical patients who are at high risk < 40) was significantly shorter, while the duration of awareness25. NICE has published the Diagnos- of adequate hypnosis (BIS 40–60) was significant- tics Guidance report (2012) which recommends ly longer in the use of sevoflurane in relation to that the pEEG monitoring is used in all the patients desflurane. Desflurane thus causes a greater depth who were under the influence of total intravenous of hypnosis in relation to the dose of sevoflurane, anesezije (TIVA)26. which in theory, should cause the same level of an- 12,28 Recommendation when using BIS monitor- esthesia . Ketamine and sometimes N2O cause ing in the case of inhalation anesthesia and the EEG activation, thus complicate an adequate inter- use of opioids is to maintain an inhalational an- pretation of BIS. esthetic flow rate so that the BIS monitor shows In the case of epidural anesthesia, clinical tri- 45–60. However, the research by Russel et al has als have shown that sedation of such patients re- pointed to the fact that 11 out of 34 patients re- quires much smaller MAC of Sevoflurane (0.59% sponded to the command during the operation compared to 0.92%) to achieve an adequate BIS29. when monitored by IFT in spite of the fact that BIS Panchal et al. have shown on the pediatric popu- has been maintained in the range 55–60. BIS has lation that BIS values range 71.65 ± 13.5 and the also demonstrated the level of awareness 660 times end-tidal concentration at 6.41 ± 0.67 at induction even though IFT showed no motor response to the of anesthesia with sevoflurane, kept at 40 (end-tid- command. The largest number of motor responses al concentration 7.08 ± 0.69) during intubation, HOW DEEP IS YOUR LOVE: AWARENESS MONITORING DURING GENERAL ANESTHESIA 165 ranged between 40 and 60 (1.5 ± 0.64) during hospital settings, PLOC is caused by inflating a bal- maintenance of anesthesia until extubation was loon in the lower part of the esophagus. done at the BIS value of 75 (0.14 ± 0.27)30. Narcotrend (Monitor Technik, Bad Bramstedt, It is important to note that among patients with Germany) represents an EEG monitor which is de- dementia value of BIS index (alertness) is lower signed to measure the depth of anesthesia in the than in patients who do not have such pathology31. form of an index that ranges from 100 (awake) to Although BIS represents a useful monitoring for 0 (electrical silence). It provides the following in- the assessment of anesthesia depth, further studies formation: current Narcotrend status and index, are necessary in patients with congenital disorders trend (cerebrogram), raw EEG signal and several of the central nervous system since BIS can give EEG derived parameters. Information are obtained abnormal responses which do not correspond to through two electrodes that are placed on the fore- the specific stage of anesthesia. This is particularly head of the patient and third, reference electrode. important in the case of the administration of high After the elimination of the artifacts, informations doses of sevoflurane which can result in epilepto- are classified as follows: A (awake), B (sedated), C genic activities32. (light anesthesia), D (general anesthesia), E (gen- eral anesthesia with deep hypnosis), F (general Other metods of aaga monitoring anesthesia with increasing burst supression). Nar- cotrend stages D and E are equivalent to BIS val- In addition to the most commonly used moni- ues ​​of 64 to 408,33. Newer devices allow transfer of toring methods of patients awareness in practice, the alfabet scale into a number scale similar to the there are numerous other methods which are less BIS index7,8. Conducted studies have indicated that frequently used. One method is to measure the Narcotrend did not effectively distinguish aware- conductivity of the skin, ie. the level of sweat pro- ness and unconsciousness especially in the case of duction. It is believed that the conductivity of the neuromuscular relaxants use, however it is believed skin is initially low and increases with the depth of that more extensive studies must be carried out in anesthesia, while it decreases again during the skin order to preserve the adequate evaluation34,35. incision. One of the main disadvantages of this The Patient State Analyzer Index (PSI; Phys- kind of monitoring is the fact that some conditions iomnetrix, North Billerica, MA) is obtained by and medications (eg, atropine) may interfere with processing the 4-channel EEG and rejecting the this kind of monitoring8. artifacts. PSI has a range of 0 to 100, similar to BIS Spontaneous surface electromyogram (SEMG) and Narcotrend monitors. It represents a clinically monitors the different muscle groups, especial- valid measure of measuring the effects of anesthe- ly facial, abdominal and neck muscles in patients sia and sedation and is designed specifically for the who are not fully paralyzed. It is considered that needs of operative and intensive care. It is known the branches of these nerves are incompletely af- that PSI adequately demonstrates a lack of aware- fected by the neuromuscular blockade. The most ness but there are no studies which show that PSI commonly used electrode is placed above the fron- is really an adequate means of measuring intraop- tal muscle and this record is called frontalis elec- erative awareness7,8,36. tromyogram (FEMG). It is considered that FEMG SNAPII (Everest Biomedical Instruments, falls during the sufficient depth of anesthesia7,8. It Chesterfield, MO) calculates the index from the is also possible to measure the lower oesophage- single-channel device that records the patient’s al contractility (LOC) since the smooth muscles EEG and subsequently processed it through its in the lower part of the esophagus retain activity unique SNAP algorithm. SNAP index is also in the even after complete muscular paralysis. Two types range between 100 and 0. Rare studies have indi- of measurements are lower oeasophageal spontane- cated that SNAP is perhaps even more sensitive ous contractility (SLOC) as well as provoked lower than BIS in detecting AAGA, especially after gen- 8 oeasophageal contractility (PLOC) . SLOC are in- eral anesthesia with sevoflurane and 2N O on 1 to duced by emotions and stress in conscious person, 1.5 MAC8,37. while PLOC is the result of the sudden esophagus Another monitoring of the depth of anesthesia distension after the arrival of the food bolus. In is Evoked brain electrical activity monitors, which 166 SJAIT 2016/5-6 measure electrical activity in certain areas of the and then to resume normal breathing through the brain in response to stimulation of specific sensory mask. During anesthesia gas flow was increased to nerve pathways. Examples of such monitorings are: 7 L/min. Failure to respond to certain stimuli, like Somatosensory evoked potentials (SSEP) – su- calling, occurred after the average 2 to 3 minutes. pramaximal stimulus is applied to peripheral nerve At the beginning of anesthesia AAITM index has while electrodes are placed over the corresponding varied from 45 to 99, while the BIS index varied sensory area. Many anesthetics increase latency from 91 to 98. Both parameters have changed with and reduce the amplitude on dose dependent man- increasing of sedation and end-tidal concentration ner. Etomidate increases the amplitude. of sevoflurane. After losing consciousness, BIS Visual evoked potentials (VEP) – diodes are ranged 51–79 (average 69), AAITM index 24–85 built in the special glasses, and in that way stim- (average 39). End-tidal concentration of sevoflu- ulation of the optic nerve is done. EEG electrodes rane at the moment of loss of consciousness was record potentials in the area of the occipital bone. 2.3 Vol% (1.3–4.0). Awakening from anesthesia Many anesthetic increase latency and reduce am- occured in average 5 minutes after the interrup- plitude on the dose-dependent manner. tion of sevoflurane delivery. On awakening, and Auditory (AEP) – represents in full awareness BIS ranged from 62–80 (average the transfer of electrical activity from cochlea to 74), while AAITM index was in the range of 14–85 cortex8. (average 40). On average the mean value of all BIS values ​​in the awake state was 85 (73–98), in the ab- The most effective methods of moitoring aaga sence of consciousness 48 (10.83). AAITM index values ​​were on average 71 (42–99) in the awake There are a large number of studies which inves- state and 21 (4.85) in the absence of conscious- tigate the effectiveness of different types of moni- ness. The study pointed to the fact that neither BIS toring in the presence of the certain level of intra- nor AAITM show a complete correlation with the operative awareness. Mashour et al have showed clinical condition or end-tidal gas concentrations. by post hoc analysis that patients’ awareness was Cause lies in the factors of time, in pharmacolog- present in 0.12% in a group where the level of con- ic and methodological variations. Both indices sciousness was monited by ETAG method, 0.05% showed variability with the fact that BIS had sig- in the group that was monitored by BIS and 0.15% nificantly less variability than AAITM index38. in the group where there was no monitoring of pa- Another study showed that AAI and BIS are tients intraoperative awareness9. Avidan et al have much more relevant in measuring the effects of showed clear intraoperative awareness in 0.24% of inhalational anesthesia (sevoflurane, N2O) from patients in the BIS group compared to 0.07% of pa- composite auditory evoked potentials index tients in the ETAG group. Also it was noted that (cAAI)39. there was 0.66% of possible intraoperative aware- Ibrahim et al. have examined the ability of BIS ness in patients in the BIS group as well as 0.28% to predict depth of sedation between sevoflurane, in the ETAG group. In both cases the superiority propofol and . BIS proved to be a better of the BIS protocol has not been proven. There predictor of sedation with propofol in relation to was no difference in the incidence of postoperative sedation with sevoflurane and midazolam40. complications between the two groups1. The fact is that in addition to BIS monitoring, Anderson et al. have investigated the effective- which isss commonly used in practice, it is neces- ness of depth of anesthesia monitoring during the sary to use all the available information that mon- wash in and wash out phase by sevoflurane by BIS itoring of other patient’s physiological functions monitoring, auditory evoked potential index (AA- provides, to use own experience and assessment. ITM) and ETAG sevoflurane. Ten patients without Bottros et al. used the inverse Turing test to indi- premedication have received 0.05 mg of fentanyl cate that the anesthetist assessment (who has been and 30 mg of propofol as coinduction. After a trained to recognize and read the clinical and EEG three-minute preoxygenation loop system has been activity) is very close to the BIS monitor. Therefore primed with 6 L/min 8% sevoflurane. The patient they have demonstrated the key role of clinicians is indicated to deeply breathe two to three times in monitoring of AAGA41. HOW DEEP IS YOUR LOVE: AWARENESS MONITORING DURING GENERAL ANESTHESIA 167 Schneider et al (2014) published a scheme for In the future depth of anesthesia monitoring the integration of BIS information and cardiovas- would have to integrate EEG data with other exter- cular variables for the production of quantitative nal information and anesthesiologist’s experience. multimodal index42,43. Depth of anesthesia moni- Appropriate anesthetic technique for awareness toring can be improved by using standard clinical prevention relies on careful monitoring of clinical parameters (heart rate, noninvasive monitoring of parameters, patient monitoring and regular aquip- blood pressure, saturation, end tidal con- ment checking. Some rules which should be ap- centration of , respiratory parame- plied in general anesthesia are as follows: patients ters, changes in heart rate and blood pressure), val- who did not receive premedication required high- ue of the anesthetic concentration (end tidal, con- er doses of intravenous induction agent, the level centration of propofol) and patient’s demographic of inhalation anesthetics during surgery should be data (age, weight, ASA status) besides using EEG monitored (ETAG), recorded and maintained in monitoring43. This combination of factors, EEG order to keep the patient asleep, the level of anal- and various standard parameters has led to the gesia should be sufficient to ensure that the patient development of index which is called Anesthe- does not feel pain if consciousness is present, if sia multimodal index of consciousness (AMIC). there is the possibility that awareness is present an AMIC combines variables obtained from EEG, the amnestic (Midazolam) should be used in or- standard monitoring parameters, each patient’s in- der to prevent patients memory of pain and events dividual data and information on the drugs used. in the operating theatre, it is useful to use earplugs Heart rate and mean arterial pressure are the main or headphones that transmit music or white noise parameters which provide information about the for the case that the patient semiconscious8. cardiovascular system. Some other parameters are: ASA Task Force recommendations on depth of the difference between inspiratory and expiratory anesthesia monitoring are based on the following44: pressure (Gas O2 IE), end expiratory concentration • Intraoperative depth of anesthesia monitoring of carbon dioxide (Gas CO2 exp), peak inspiratory should rely on clinical techniques and convention- pressure (SPIRO Ppeak), end expiratory gas con- al patient monitoring. Muscle relaxants can inter- centrations (MAC exp), age, gender, BMI, etc. The fere with adequate monitoring of the patient in conclusion of this study is that multimodal inte- terms of detecting target or reflex movements. gration of standard monitoring and EEG param- • Monitoring of the electrical activity of the eters can even more accurately reflect the level of brain is worth monitoring but it shouldnt be used anesthesia when compared with only one of these in assessing the depth of anesthesia in all patients. aspects43. It is considered that the lack of using this • Monitoring of brain function is not used rou- index is in the fact that it is based primarily on the tinely in patients under general anesthesia, nor for parameters measured and processed by a machine routine depth of anesthesia monitoring. Its use is giving a new index parameter. It is unacceptable recommended for selected cases of patients who to use of any kind of „black box“ when it comes to require lower doses of anesthetic, in trauma sur- patients’ lives. It considers that it is better to pres- gery, caesarean section and total intravenous an- ent monitoring parameters to the clinician, who esthesia. will then include his/hers experience and make If the patient states that he has been aware dur- the final decision on the amount of anesthetics and ing surgery, one should take the following actions8: opioids42. anesthesiologist must visit the patient as soon as possible and examine what the patient remembers, Protocols used in practice for avoiding aaga he must review the documentation and check the equipment in order to find possible defects, he Research in the field points to the fact that very must assess patient’s condition and explain where few centers have developed protocols for the pre- the mistake occured, he must note the problem so vention or treatment of AAGA. It is believed that that future anesthesiologists have that problem in this is the consequence of AAGA being considered mind when they come in contact with the same pa- so rare that it is not necessary to develop such a tient, he must offer the patient further follow-up as strategy5. well as psychological help and note that it has been 168 SJAIT 2016/5-6 offered, he must convince the patient that he can compared with the isolated forearm technique. Anaesthesia further undergo general anesthesia with minimal 2013; 68:1010–20. risk of future episodes of consciousness. Younger 11. Schneider G, Sebel PS. Monitoring depth of anesthe- sia. Eur J Anaesthesiol Suppl 1997; 15:21–8. anesthesiologists should inform the competent an- 12. Sanders RD, Tononi G, Laureys S. Sleigh JW. Un- esthesiologist about the problem that occurred. responsiveness unconsciousness. Anesthesiology 2011; Certainly, the clinician has the obligation to 116:946–59. inform the legal department of the hospital, the 13. Evans JM, Davies WL. Monitoring anaesthesia. Clin hospital administration, the patient’s general phy- Anesth 1984; 2:243–62. 14. Maenpaa M, Penttila J, Laitio T, Kaisti K, Kuusela T, sician, to administer bensodiazepine to patients Hinkka S, Scheinin H. The effects of surgical levels of sevo- who are extremely upset. flurane and propofol anaesthesia on heart rate variability. Eur J Anaesthesiol 2007; 24(07):626–33. Conclusion 15. Russell IF. Fourteen fallacies about the isolated fore- arm technique, and its place in modern anaesthesia. Anaest- The administration of neuromuscular block- hesia. 2013; 68:677–81. 16. Zand F, Hadavi SM, Chohedri A, Sabetian P. Survey ers prevents motor response of patients, therefore on the adequacy of depth of anaesthesia with bispectral index it takes a lot of experience of the anesthesiologist and isolated forearm technique in elective Caesarean section and adequate monitoring in order to determine under general anaesthesia with sevoflurane. Br J Anaesth the level and state of mind of the patient. The most 2014; 112:871–8. commonly used monitoring in clinical practice is 17. Russell IF. Midazolam-alfentanil: an anaesthetic? An investigation using the isolated forearm technique. Br J Ana- still BIS monitoring. esth 1993; 70:42–6. 18. Sleigh J. The place of the isolated forearm technique References: in modern anaesthesia: yet to be defined. Anaesthesia 2013; 68:681–3. 1. Avidan MS, Jacobsohn E, Glick D, et al. BAG-RECALL 19. Pandit JJ, Cook TM. National Institute for Health and Research Group. Prevention of intraoperative awareness in a Care Excellence guidance on measuring depth of anaesthe- high-risk surgical population. N Engl J Med, 2011; 365:591– sia: limitations of EEGbased technology. Br J Anaesth 2013; 600. 110:325–8. 2. Myles PS, Leslie K, McNeil J, Forbes A, Chan MT. Bi- 20. Pandit JJ, Cook TM, Jonker WR, O’Sullivan E. A na- spectral index monitoring to prevent awareness during ana- tional survey of anaesthetists (NAP5 Baseline) to estimate esthesia: the B-Aware randomised controlled trial. Lancet an annual incidence of accidental awareness during general 2004; 363:1757–63. anaesthesia in the UK. Anaesthesia 2013; 68:343–53. 3. Avidan MS, Zhang L, Burnside BA, Finkel KJ, Searle- 21. Russell IF. The Narcotrend „depth of anaesthesia“ man AC, Selvidge JA, Saager L, Turner MS, Rao S, Bottros monitor cannot reliably detect consciousness during general M, Hantler C, Jacobsohn E, Evers AS. anaesthesia: an investigation using the isolated forearm tech- and the bispectral index. N Engl J Med 2008; 358:1097–108. nique. Br J Anaesth 2006; 96:346–52. 4. Pollard RJ, Coyle JP, Gilbert RL, Beck JE. Intraoperative 22. Jameson LC, Sloan TB. Using EEG to monitor anest- awareness in a regional medical system: a review of 3 years’ hesia drug effects during surgery. J Clin Monit Comput 2006; data. Anesthesiology 2007; 106:269–74. 20(6):445–72. 5. Pandit JJ, Cook TM, Jonker WR, O’Sullivan E. A na- 23. Otto KA. EEG power spectrum analysis for monito- tional survey of anaesthetists (NAP5 Baseline) to estimate ring depth of anaesthesia during experimental surgery. Lab an annual incidence of accidental awareness during general Anim 2008; 42(1):45–61. anaesthesia in the UK. Anaesthesia 2014; 68:343–53. 24. Nunes RR. Entropy: A new method of measuring 6. Griffith D, Jones JB. Awareness and memory in anaest- depth of anesthesia. Comparative study with bispectral index hetized patients. Br J Anaesth 1990; 65:603–7. during clinical evaluation in of patients 7. Kaul HL, Bharti N. Monitoring depth of anaesthesia. anesthetized with sevoflurane. Rev Bras Anestesiol 2004; Indian J Anaesth 2002; 46(4):323–32. 54(3):289–302. 8. Sinha PK, Koshy T. Monitoring devices for measu- 25. Punjasawadwong Y, Phongchiewboon A, Bunchung- ring the depth of anaesthesia- an overview. Indian J Anaesth mongkol N. Bispectral index for improving anaesthetic de- 2007; 51(5):365–81. livery and postoperative recovery. Cochrane Database Syst 9. Mashour GA, Shanks A, Tremper KK, Kheterpal S, Rev 2007; Issue 4. Art. No:CD003843. Turner CR, Ramachandran SK, Picton P, Schueller C, morris 26. National Institute for Health and Care Excellence – M, Vandervest JC, Lin N, Avidan MS. Prevention of intrao- NICE DiagnosticsGuidance: Depth of anaesthesia monitors. perative awareness with explicit recall in an unselected sur- Bispectral index (BIS), E-Entropy and Narcotrend-Compact gical population. A randomized comparative effectiveness M. 2012. www.nice.org.uk/dg6 (accessed 29 May 2016). trial. Anesthesiology 2012; 117:717–25. 27. Klopman MA, Sebel PS. Cost-effectiveness of bi- 10. Russel F. The ability of bispectral index to detect in- spectral index monitoring. Curr Opin Anaesthesiol 2011; tra-operative wakefulness during isoflurane/air anaesthesia, 24(2):177–81. HOW DEEP IS YOUR LOVE: AWARENESS MONITORING DURING GENERAL ANESTHESIA 169 28. Kim JK, Kim DK, Lee MJ. Relationship of bispectral and bispectral index values during the perioperative period. index to minimum alveolar concentration during isoflurane, Anesth Analg 2002; 95:1669–74. sevoflurane or desflurane anaesthesia. J Int Med Res 2014; 38. Wong CA, Fragen RJ, Fitzgerald P, McCarthy RJ. A 42(1):130–7. comparison of the SNAP II and BIS XP indices during sevo- 29. Hodgson PS, Liu SS. Epidural lidocaine decreases se- flurane and nitrous oxide anaesthesia at 1 and 1.5 MAC and voflurane requirement for adequeste depth of anesthesia as at awakening. Br J Anaesth 2006; 97:181–6. measured by the Bispectral Index Monitor. Anesthesiol 2001; 39. Anderson RE, Barr G, Assareh H, Jakobsson J. The

94:799–803. AAITM index, the BIS index and end-tidal concentration du- 30. Panchal NN, Swadia VN, Patel MG. Correlation of ring wash in and wash out of sevoflurane. Anaesthesia 2003; BIS index with sevoflurane concentration in paediatric ana- 58:531–5. esthesia. Nat J Med Res 2014; 4(2):156–60. 40. Nishiyama T. Composite-, plain-auditory evoked po- 31. Renna M, Handy J, Shah A. Low baseline Bispectral tentials index and bispectral index to measure the effects of Index of the electroencephalogram in patients with demen- sevoflurane. J Clin Monit Comp 2013; 27(3):335–9. tia. Anesth Analg 2003; 96:1380–5. 41. Ibrahim AE, Taraday JK, Kharasch ED. Bispectral in- 32. Galante D, Fortarezza D, Caggiano M, de Francisci dex monitoring during sedation with Sevoflurane, Midazo- G, Pedrotti D, Caruselli M. Correlation of bispectral index lam and Propofol. Anesthesiol 2001; 95:1151–9. (BIS) monitoring and end-tidal sevoflurane concentration in 42. Bottros MM, Palanca BJA, Mashour GA, Patel A, Bu- a patient with lobar holoprosencephaly. Rev Bras Anestesiol tler C, Taylor A, Lin N, Avidan MS. Estimation od the bi- 2015; 65(5):379–83. spectral index by anesthesiologists: An inverse Turing test. 34. Kreuer S, BiedlerA, Larsen R, Schoth S, Altmann S, Anesthesiol 2011; 114:1093–101. Wilhelm W. TheNarcotrend™ – a new EEG monitor designed 43. Sleigh J. No monitor is an island: depth of anaesthesia to measure the depth of anaesthesia. A comparison with bi- involves the whole patient. Anesthesiol 2014; 120:799–800. spectral index monitoring during propofolremifentanil-ana- 44. Schneider G, Jordan D, Schwarz G, Bischoff P, Kalk- esthesia. Anaesthesist 2001; 50:921–5. man CJ, Kuppe H, Rundshagen I, Omerovic A, Kreuzer 35. Schneider G, Kochs EF, Horn B, Kreuzer M, Ningler M, Stockmanns G, Kochs EF; European Multicenter EEGA- M. Narcotrend® does not adequately detect the transition be- EP Anesthesia Monitoring Study Group and Research Group tween awareness and unconsciousness in surgical patients. Knowledge-based Signal Processing. Monitoring depth of Anesthesiol 2004; 101:1105–11. anesthesia utilizing a combination of electroencephalograp- 36. Russell IF. The Narcotrend ‘depth of anaesthesia’ mo- hic and standard measures. Anesthesiol 2014; 120:819–28. nitor cannot reliably detect consciousness during general 45. American Society of Anesthesiologists Task Force on anaesthesia: and investigation using the isolated forearm Intraoperative Awareness. Practice advisory for intraoperati- technique. Br J Anaesth 2006; 96(3):346–52. ve awareness and brain functionmonitoring, A Report by the 37. Chen X, Tang J, White PF, Wender RH, Ma H, Slo- American Society of Anesthesiologists Task Force on Intrao- ninsky A, Kariger R. Acomparison of patient state index perative Awareness. Anesthesiology 2006; 104:847–64.