RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, KARNATAKA
BANGALORE
ANNEXURE – II
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1 / Name of the candidate and address ( in block letters) / : / Dr. Rahul.rDEPARTMENT OF ANESTHESIOLOGY
RAJARAJESWARI MEDICAL COLLEGE, BANGALORE - 560074
Permanent address / : / Dr. Rahul
s/o dr.M ramaswamy
51 a duO RESIDENCY JAKKUR PLANTATION CLUB
JAKKUR
BANGALORE 560064
2 / Name of the institution / : / RAJARAJESWARI MEDICAL COLLEGE,
BANGALORE – 560074
3 / Course of study and subject / : / M.D. (Anesthesiology)
4 / Date of admission to the course / : / 30th May 2012
5 / Title of Topic / : / Assessment of depth of anaesthesia and awareness during General Anaesthesia using Evan’s score and Bispectral index monitoring
6 / Brief Resume of the intended work
6.1 / Need for the study
Despite remarkable improvements in the assessment of the cardiovascular and respiratory systems during anesthesia, determination of the effect of anesthetic agents on the central nervous system had remained a challenge. Technologies that permit routine neurophysiologic monitoring of the central nervous system provide a direct measure of anesthetic effect during anesthesia.
Awareness during general anaesthesia can be defined as a degree of consciousness, revealed by the occurrence of explicit or implicit memory of intra operative events . During such an episode information may be stored temporarily into short term memory and may or may not be stored permanently in long term memory. Two clinical signs possibly predicting
the recall are movement and autonomic response1
Stages of Awareness are1,2:-
1. Conscious awareness with complaint of pain perception.
2 .Conscious awareness with explicit recall but without pain.
3.Concious wakefulness (ability to respond to simple oral commands)
without explicit recall and pain but implicit memory.
4.Subconcious awareness without explicit recall but evidence of implicit memory of intra operative events.
5. No awareness.
Consequences of awareness during general anaesthesia are:
1.Temporary emotional stress
2.Implicit memory manifested by acute or chronic Psychosis
3.Recurrent Nightmares
4.Psychotherapy
5.Post Traumatic stress disorders
Risk factors for awareness are:
- Inadequate delivery of anaesthesia to patients with a normal
anaesthetic requirement.
- Delivering adequate anaesthesia to patients with low anaesthetic
requirement or low cardiac reserve.
- Anaesthetic requirements may be higher than usual in patients who
are tolerant to sedatives or analgesic drugs (alcohol and benzodiazepines) Hence assessment of the depth of Anaesthesia is very important.1
The depth of anaesthesia can be assessed clinically with subjective methods ie Evan’s score or PRST score (pressure, rate, sweating, tears respectively). Adding up the points of all four parameters determine the total score which can range from 0 to 8. There is inadequate depth of anesthesia if the score is more than 3.To estimate the depth of anesthesia, objective methods can be used that are based on recording and analysis of brain electrical activity.This study is required to correlate and contrast one subjective Evan’s score (PRST score) and one objective (Bispectral index) method for the assessment of the depth of anaesthesia with the aim to prevent awareness. It allows anaesthesiologists to deliver anesthesia with more precision,
assess and respond appropriately to a patient’s changing condition during surgery1,3
-
6.2 / Review of Literature
Various methods have been described to measure the depth of anaesthesia. John Snow in 1847, described five degrees of narcotism for ether anaesthesia. These were later refined by Guedel into
four stages on the basis of somatic muscle tone, respiratory
parameters and ocular signs 1,4In 1954, Artusio divided Guedel’s stage I into 3 planes 1,5. In 1957, Woodbridge defined anaesthesia as having four components; sensory blockade, motor blockade, blockade of autonomic reflexes and loss of consciousness1,6. According to Prys-Roberts, common feature of general anaesthesia is suppression of conscious perception of noxious stimuli. Analgesia, autonomic stability and muscle relaxation are desirable but not actual components of anaesthesia. Prys-Roberts divided the noxious stimuli into somatic and autonomic components, which were further, divided into sensory, motor ,respiratory, haemodynamic, pseudo motor and hormonal.1,7
There are various subjective and objective methods of assessing
depth of anaesthesia . Subjective methods rely on the
movement and autonomic response to stimuli and depend on the opinion
and experience of an anaesthetist. The objective methods rely on the
sensitivity of the monitor.
Subjective methods1
1. Autonomic response
2. Patient Response to Surgical Stimulus (PSRT) Scoring system
3. Isolated forearm technique
B. Objective methods
4. Spontaneous surface electromyogram (SEMG)
. Lower oesophageal contractility (LOC)
. Heart rate variability (HRV)
Electroencephalogram and derived indices
.Compressed spectral array/ Spectral edge frequency/ Median frequency
.Bispectral index
.Entropy
.Narcotrend index
.Patient state index
.Snap index
.Cerebral state index
5. Evoked potentials
.Somatosensory evoked potentials
.Visual evoked potentials
.Auditory evoked potentials
.Auditory evoked potential index
.A- Line auto regressive index
Evans JM et al 1984 described a clinical score to assesses autonomic activity related to awareness as P (systolic blood P ressure), R (heart R ate), S ( S weating) and T ( T ears). This system has the advantages of being simple and not requiring any specialized equipment. Measurement of heart rate and blood pressure while regularly assessing pupil size, the presence of sweating and lacrimation, provide useful information regarding the adequacy of analgesia and depth of anaesthesia.
A report was published by the American Society of Anesthesiologists Task Force on Intraoperative Awareness in (2006) . In their report “Practice advisory for intraoperative awareness and brain function monitoring”,they conclude that clinical techniques and conventional monitoring systems are valuable in the monitoring of intra operative awareness8 .
Scott Kelley in his book Monitoring level of consciousness and sedation in Anaesthesia states that - BIS is a proprietary algorithm (Aspect Medical Systems, Natick, ) that converts a single channel of frontal EEG into an index of hypnotic level . To compute the BIS, several variables derived from the EEG time domain (burst suppression analysis), frequency domain (power spectrum, bispectrum:interfrequency phase relationships) are combined into a single index of hypnotic level which is used to help assess intraoperative consciousness9.
Glass et al in their article in 1997 used bispectral analysis to measure sedation and memory effects of propofol, midazolam, isoflurane, and alfentanil in healthy volunteers and concluded that BIS index is a valuable monitor to measure the same10
Jasmina Smajic et al in their study in 2011 concluded that BIS monitoring with clinical assessment allows anesthesiologists precise decision-making and balancing the dosage of anaesthetics and other medications (analgesics and cardiac agents) in patients with higher operative risk11.
Kaul et al in their article in 2002 stated that any single method is not reliable to measure the depth of anaesthesia for all patients and all anaesthetic agents, using more than one method is more accurate12
6.3 / Objectives of the study
1)To evaluate the incidence of awareness during general anesthesia and any adverse effects perceived.
2)To evaluate the efficacy of PRST score in assessment of depth of anaesthesia
3)To evaluate the efficacy of BIS- monitoring to assess the depth of anaesthesia
4)To evaluate and correlate the efficacy of BIS monitoring along with PRST score in assessment of depth of anaesthesia
7 / Materials and methods
7.1 / Source of data
Study will be conducted on patients undergoing all types of surgical procedures under General anaesthesia at Raja Rajeshwari Medical college and Hospital ,Bengaluru
7.2 / Methods of collection of data ( including sampling procedure, if any)
Sampling Method – Simple random sampling
A prospective clinical study will be conducted on 160 patients undergoing surgery in various specialties under general anesthesia at Raja Rajeswari Medical college & Hospital Bengaluru . These patients will be divided into two groups of 80 patients each by consecutive selection.
Inclusion Criteria:
Subjects of both sexes aged 20-70 years.
American Society of Anesthesiologists (ASA) grade I and II .
Exclusion criteria
All patients less than 20 years and over 70 years.
Patients with ASA grade lll and grade lV.
Methodology
After approval by the institutional ethics committee, informed written consent will be taken from patients after explaining the procedure in their own language.
Group 1- depth of anesthesia will be assessed by Evan’s score or PRST score
Group 2- by BIS index monitoring and PRST score
Before induction, all patients were premeditated using midazolam (0.05 mg / kg).For induction of anesthesia Inj.Propofol will be used with a dose of 1.5 to 2.5 mg/kg, for muscle relaxation appropriate dose of atracurim /vecuronium/rocuronium will be used while the anesthesia is maintained with oxygen, nitrous oxide and sevoflurane, and analgesia with opioids.
Group-1 PRST Score
Baseline reading before General anaesthesia / t0
Depth of anesthesia assessed at intubation / t1
At first skin incision / t2
30 minutes after first skin incision / t3
30 minutes after t3 reading / t4
Immediately after placing the last suture in the skin / t5
In the first group of respondents, before the introduction of anaesthesia blood pressure and heart rate values are noted (t0). At the time of intubation (t1), the first skin incision (t2), 30 min after the first incision (t3), 30 minutes after t3 reading (t4)and immediately after placing the last suture of the skin. (t5) the same parameters are noted ad changes recorded. The occurrence of tears in the closedeye or while opening the eye, sweating are noted at the same time intervals.
Each parameter was scored from 0 to 2 and by summing up all the points obtained by the PRST score; the depth of anaesthesia was estimated.
PRST SCORE(Evans score 1987)
Pressure, heart rate, sweating, tear production
Systolic arterial pressure
Increase / < 15mmHg / 0
Increase / 15-30mmHg / 1
Increase / >30 mm Hg / 2
Heart rate
Increase / <15bpm / 0
Increase / 15-30 bpm / 1
Increase / >30bpm / 2
Sweat production
Dry skin / 0
Moist skin / 1
Drops of sweat visible / 2
Tear production
No tears visible / 0
Flow of tears in opened eye / 1
Flow of tears in closed eyes / 2
Greater than 3 points = inadequate anaesthetic depth
In the second group of subjects, to estimate the depth of anesthesia, a BIS index monitor is used. Before the introduction of anesthesia unilateral BIS sensor, that records the EEG waves, is mounted on cleaned and dried fore-head.BIS sensor with the appropriate cable is connected with the BIS monitor that displays the EEG waves and BIS index value. Using a sensor that is placed on the patient’s forehead BIS monitoring translates information from the electroencephalogram into a simple number that is read on a monitor and represents the patient’s state of mind.
The BIS index values are maintained in the range 40-60, which is considered adequate depth.While noting BIS index quotation, the PRST score is determined and noted, too. BIS index is monitored continuously, values recorded at the same intervals as in Group-1
Group 2 - BIS INDEX
Baseline reading before General anaesthesia / t0
the time of intubation / t1
the first skin incision / t2
30 min after the first incision / t3
30 min after the t3 reading / t4
immediately after placing the last suture in the skin / t5
.
Normal Bispectral index value Correlation
May respond to loud commands or mild prodding and shaking / 80
Moderate sedation / 60
General anesthesia
.low probability of explicit recall
.unresponsive to verbal stimulus / 40
Deep hypnotic state
Burst suppression / 20
Flat line EEG / 0
With both groups of respondents an interview will be conducted 24 hr after
surgery, in order to obtain information about whether something is heard, seen or felt during the general anesthesia according to the protocol.
STATISTICS
The data collected will be analyzed statistically using descriptive statistics The results will be depicted in the form of percentages, graphs , charts and tabular columns.
Statistical analysis is performed by descriptive statistics to calculate
the mean and standard deviation.The t-test, χ ² tests for calculating the materiality will establish the results.Statistical analysis is performed with a confidence interval of 95%, a value of p <0.05 is considered significant.
PRST score mean values in the first group of respondents
PRST mean scores in Group 1
Group / N / Mean / Standard deviation
t1 / 1
t2 / 1
t3 / 1
t4 / 1
t5 / 1
PRST mean scores in Group 2
Group / N / Mean / Standard deviation
t1 / 2
t2 / 2
t3 / 2
t4 / 2
t5 / 2
7.3 / Does the study require any investigation or intervention to be conducted on patients or other humans or animals? if so please describe briefly
NO
7.4 / Has ethical clearance been obtained from your institution in case of 7.3 ?
Yes
8 / List of References
1)Millers anaesthesia–7th Edition USA/Churchill livingstone Elsevier 2009 Monitoring the depth of anaesthesia chapter 31–p1229-1245
2) Griffith D, Jones JB. Awareness and memory in anaesthetised patients. Br J Anaesth 1990; 65: 603-7
3) Evans JM, Davies WL. Monitoring anaesthesia. Clin Anesth 98484; 2:1984 243-62
4)Guedel AE. Inhalational anesthesia. A fundamental guide.
Macmillan, New York, 1937.
5)Artusio JF, Jr. Di-ethyl ether analgesia: A detailed description
of the first stage of ether analgesia in man. J Pharmacol Exp Ther 1954; 111: 343.
6) Woodbridge PD. Changing concepts concerning depth of
anaesthesia. Anaesthesiology1957;18:536
7)Prys -Roberts C. Anaesthesia : A practical or impractical construct? BrJ Anaesth 1987:59: p1341-1345
8). Practice advisory for intraoperative awareness and brain function monitoring, A Report by the American Society of Anesthesiologists Task Force on Intraoperative Awareness. Anesthesiology 2006; 104: 847-64
9) Scott Kelley Monitoring level of consciousness and sedation in Anaesthesia Chapter1: p2-9
10)Glass PS, Bloom M, Kearse L, Rosow C, Sebel P, Manberg P. Bispectral analysis measures sedation and memory effects of propofol, midazolam, isoflurane, and alfentanil in healthy volunteers. Anesthesiology 1997; 86: 836-47
11) Jasmina Smajic, Mirsada Praso, Mirsad Hodzic, Samir Hodzic, Amna Srabovic-Okanovic, Nedim Smajic, Zinka Djonlagic Assessment of Depth of Anesthesia: PRST Score Versus Bispectral Index MED ARH 2011; 65(4): 216-220.
12) Kaul HL, Bharti N. Monitoring depth of anaesthesia. Indian J Anaesth. 2002; 46 (4): 323-332
9 / Signature of Candidate / DR.RAHUL
10 / Remarks of guide
11 / 11.1 / Name and designation of the Guide / DR.RANGALAKSHMI .S
POFFESSOR
RAJA RAJESHWARI MEDICAL COLLEGE
BANGALORE-560074
11.2 / Signature
11.3 / Co- guide (if any)
11.4 / Signature
11.5 / Head of the Department / Dr.SAHAJANANDA
PROFFESSOR &HOD
RAJA RAJESHWARI MEDICAL COLLEGE
BANGALORE-560074
11.6 / Signature
12 / 12.1 / Remarks of the Chairman and Principal
12.2 / Signature
Certificate