neuroanaesthesia

1. DR. YAMINI DHENGLE
ASSISTANT PROFESSOR
G.S.M.C. & K.E.M. HOSPITAL
MUMBAI
PROGRESS IN
NEUROANESTHESI
A

3. Discovery of trephined Neolithic skulls in 1873 at
Lozère (France), dating the first craniotomies
Historians believed - openings were made to
alleviate pain or to allow the escape of demons,
spirits, and supernatural elements from the head
Devoid of modern anesthetic agents or techniques.
Descriptions of the pain-relieving properties of
coca leaves and daturas in early historical
records.

4. • The Greek physician Hippocrates (460–370 BC)
described trephination for several pathologies of the
central nervous system performed in ancient
Greece;
• Blood under cranium - removed by perforating the
skull  epidural and subdural hematomas.
• He used linen dressings soaked in wine for their
soporific effects in analgesia.
De material medica by Dioscorides (40–90 AD), a Greek
physician, pharmacologist, and botanist, the narcotic effects of
mandrake, henbane, and opium, as well as the effects of
alcohol,
 use of laudanum, a tincture containing approximately 10%
opium by weight.

5. • Carbon dioxide, hydrogen, and nitrogen were
discovered toward the end of the 18th century
• Sir Humphry Davy (1778–1829), who
established the Pneumatic Institute in Bristol,
England, in 1799
• He noted that nitrous oxide could produce a
state of insensibility and relive surgical pain.
• Wells, a dentist ,Connecticut, in 1844, 
teeth extraction under nitrous oxide.

6. • W.T.G.Morton’s public demonstration of ether anesthesia on October 16, 1846, at
the Massachusetts General Hospital,17 when Dr. John C. Warren (1778–1856)
removed a vascular tumor from the submandibular region in a patient
anesthetized with sulphuric ether.

7. • At the turn of the 20th century, debates regarding the relative merits of chloroform and
ether.
• Victor Horsley (1857–1916)  series of experiments in animals from 1883 to 1885
although ether was safer, it was not to be recommended in favor of chloroform,
because it produced a rise in blood pressure and an increase in blood viscosity, with a
consequent potential for hemorrhage.
• Fedor Krause (1857–1937) used chloroform alone, while Emil Theodor Kocher
(1841–1917) hesitated to do so because of its tendency to lower the blood pressure.
• Harvey Cushing (1869–1939), on the other hand, was impressed with chloroform’s
efficacy but preferred a cautious approach to anesthesia, favouring ether and
restricting his use of chloroform to children.

8. • Cocaine had been formally discovered in 1860 and was
introduced into surgery in 1884.
• Use of procaine, which was first synthesized in 1905,
immediately became commonplace among surgical
anesthetics.
• Most neurosurgeons used local infiltration anesthesia for
select cases, but beginning in 1913 with its popularization by
de Martel, it became a common practice to use it for all
craniotomies.
• By 1917, Harvey Cushing recommended the use of local
anesthesia for all neurosurgical cases.

9. NEUROANAESTHESIA – A SUBSPECIALITY

10. RESEARCH
• Neuroanesthesiology research has prospered most when addressing 3
broad topics:
(1) the mechanisms of brain injury and cerebral protection,
(2) the pharmacology and physiology of neuroanesthesia-related
interventions, and
(3) facilitating the clinical practices and understanding of disease pathology,
as related to neurosurgeons and neurointensivists.

11. HISTORY
• 1949- Albert Faulconer, Mayo Clinic (father of neuroanesthesiology). With neurologist, Reginald Bickford,
began work on the electroencephalogram (EEG) responses to anesthetics.
• He experimented with a controller device that would adjust the dosing of a barbiturate infusion, and in turn
anesthetic depth, based on EEG pattern
• EEG use to predict outcomes after cerebral hypoxia

12. • 1961- John D. “Jack” Michenfelder, MD
(father of modern neuroanesthesiology) 
discover profound hypothermia to facilitate the
clipping of cerebral aneurysms.
• Developed the canine sagittal sinus outflow
model for quantifying cerebrocortical blood flow
and oxygen consumption in virtually real time
• The model was also expanded to allow
measurements of intracranial pressure (ICP)
and the EEG.
• Metabolic depression by barbiturates peaked
when the EEG became isoelectric, correlated
with brain electrical activity.

13. • In 1965, Allan Brown of Edinburgh, Scotland, and Andrew Hunter of Manchester, England, co-
founded the aforementioned Neuroanesthesia Traveling Club of Great Britain and Ireland.
1961 Commission on Neuroanesthesia, sponsored by the World Federation of Neurology, and a
June 1973 organizational meeting in Philadelphia of the Neurosurgical Anesthesia Society
(NAS).
• At the first annual meeting of the organization in October 1973, the NAS’s name was changed to
the Society of Neurosurgical Anesthesia and Neurological Supportive Care (SNANSC)
• In 1986, the name of the organization was changed to Society of Neurosurgical Anesthesiology
and Critical Care (SNACC) and the SNACC abbreviation was retained in 2009.
• February 1999- Formation of the Indian Society of Neuroanaesthesiology and Critical Care
(ISNACC)

14. HYPOTHERMIA
• In 1999, Todd and Warner* invited some 2-dozen neuroanesthesia researchers to Iowa City, 3-day
meeting. The group would label itself the Unincorporated Neuroanesthesia the International
Neuroanesthesia Research Group 
Induced Hypothermia for Aneurysms Surgery Trial (IHAST)
• in 3-month outcome data on 1000, 30-center, 3-continents
• Subgroup analysis of the relationship of hypothermia with outcomes of anesthetic technique and
glucose concentrations.
• Ironically, although the IHAST research proved negative  No better outcome in hypothermia
group, increased incidence of bacteremia
Induced hypothermia  improving neurological outcomes in adult survivors of out-of-hospital
cardiac arrest
in neonates who have sustained hypoxic-ischemic encephalopathy
*Todd MM, Hindman BJ, Clarke WR, et al. Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST) Investigators. Mild intraoperative hypothermia
during surgery for intracranial aneurysm. N Engl J Med. 2005;352:135–145

15. GLUCOSE & CORTICOSTEROIDS
• 1987 -- William Lanier reported in Anesthesiology^^ that small, clinically relevant
volumes of 5% glucose-containing solution (ie, 1.05L per 70kg body weight)
meaningfully worsened outcome after a cerebral ischemic event in a non-human
primate model.
• 1996 -- Wass and Lanier et al*  corticosteroids—once indiscriminately used in
neurosurgical patients—could produce adverse postischemic outcomes as a
result of glucose-dependent and glucose-independent effects. This research
also had an effect on lessening corticosteroid use clinically
^^Wass CT, Lanier WL. Glucose modulation of ischemic brain injury: review and clinical recommendations. Mayo Clin Proc. 1996;71:801–812.
*Wass CT, Scheithauer BW, Bronk JT, et al. Insulin treatment of corticosteroid-associated hyperglycemia and its effect on outcome after forebrain ischemia in rats.
Anesthesiology. 1996;84:644–651.

16. CALCIUM CHANNEL BLOCKERS
• Petter Steen and Sven Gisvold (a colleague of Peter Safar) from Trondheim, Norway,
joined forces in Rochester, in 1983 to introduce a slightly improved version of Safar’s
primate global brain ischemia model to the Michenfelder laboratory. This model was
then used to demonstrate the protective effects of the calcium entry blocker,
nimodipine.
• Calcium entry blockers, were evaluated by neuroanesthesiologists as a treatment for
improving neurological outcomes after cardiac arrest.
• This study later on made neurosurgeons adopt it as a method for improving outcomes
from vasospasm after subarachnoid hemorrhage
Steen PA, Gisvold SE, Milde JH, et al. Nimodipine improves outcome when given after complete cerebral ischemia in primates. Anesthesiology. 1985;62:406–
414

17. VENOUS AIR EMBOLISM
Maurice S. Albin* –
• VAE occurrence is not limited only to the sitting position, but can occur as well during
prone, supine, and lateral surgical procedures
• 1976  Tung air bubble illumination unit
- illuminated box with a magnified glass anterior surface.
- clamped on a segment of the air aspiration catheter
- helps to magnify and illuminate any passing air bubbles.
• Te99 lung scans  >25ml of air were aspirated from a right atrial catheter and the
patient appeared to be doing well symptomatically, pulmonary perfusion defects,
some quite severe, were present as long as 11 days after surgery
• Optimal air aspiration occurred with the multiorificed catheter tip position within the
area 2.0 cm below the junction of the superior vena cava and the right atrium .
*Albin MS, Carroll RG, Maroon JC: Clinical considerations concerning detection of venous air embolism. Neurosurgery 1978; 3:380–4.

18. PICCS ARE PASSÉ
• 122 patients 67.2% PICC were optimally placed –
below the carina (chest x-ray) at junction of SVC &
RA.
• Misplaced or Malpositioned – 40 out of 122
• Above the carina  27
• Rt. Atrium  6
• IJV/ opposite subclavian  7
• CVC optimal position  90-95%

19. ADVANCES IN INTRAVENOUS AGENTS
• Barbiturates
- used in neurosurgical procedures for more than 80 years
- neuroprotective – decreases CBF, CMRO2, ICP
• Etomidate
- minimal cardiorespiratory effects,
- neuroprotective

20. PROPOFOL
• it is a powerful hypnotic that does not increase the intracranial pressure.
• delay of recovery is short even after several hours of continuous infusion
early neurologic examination.
• Lesser incidence of PONV
• Continuous infusion should be preferred to bolus in order to prevent
hypotension and decrease of the cerebral perfusion pressure.

21. • Target-controlled infusion models based on effect site concentrations are now
available through several softwares.
• Useful for awake craniotomy and functional neurosurgery.
• Useful during evoked potential monitoring.
• The level of consciousness is easily fixed between deep anaesthesia and light
sedation permitting to ask the patient to move following orders.

22. OPIOIDS
• Morphie , norphine
• Advent of the semisynthetic opioids
fentanyl, sufentanil, and alfentanil
lacked histamine release
emergence more predictable
• Sufentanil and fentanyl delayed and recurring respiratory depression
• REMIFENTANIL
- earlier return of some functions than with sufentanil or fentanyl.
- One of the most desirable - rapid anesthetic emergence
- rapid post-operative recovery is essential to assess neurologic function
- No respiratory depression post-op

23. KETAMINE
• Assumed has no role in neuroanesthesia  potential for undesirable
cerebral hemodynamic effects.
• Neuroprotection  Non-competitive inhibition of N-methyl-D-aspartate
(NMDA) receptors & reduction in glutamate excitotoxicity
• Ketamine  not be considered absolutely contraindicated in TBI
patients.

24. MUSCLE RELAXANTS
Long acting muscle relaxants  Pancuronium, Doxacurium
Intermediate non-depolarizing muscle relaxants used in neurosurgical
anaesthesia  Atracurium, cisatracurium, vecuronium and rocuronium
Cisatracurium- in less cerebral and cardiovascular side-effects compared with
an equipotent dose of atracurium

25. TO USE OR NOT???
Endotracheal intubation can be easily performed without muscle relaxants, although sometimes
at the expense of haemodynamic alterations
Artificial ventilation  easily controlled during anaesthesia without muscle relaxants.
No muscle inside the skull that could be paralysed to improve the neurosurgeon’s
performance.
Numerous neurosurgical procedures do not absolutely require muscle relaxants or even
contraindicate their use
 intraoperative monitoring of motor evoked responses
 intraoperative facial nerve monitoring during cerebellopontine angle surgery
 Awake craniotomies for epilepsy surgery or surgery involving the eloquent cortex

26. DEXMEDETOMIDINE
• Stability of intracranial hemodynamics
• Attenuates hemodynamic response to laryngoscopy, intubation & pin insertion
• Reduces norepinephrine levels post ischaemia & anesthesia emergence
• Conscious sedation  Early awakening
Infusion used for  Functional neurosurgery, Carotid endarterectomy
adjuvant during general anesthesia
• Less agitation and respiratory depression

27. INHALATIONAL AGENTS
Ether (1856)
Chloroform (1847)
EMO vapouriser with
Oxford inflating
bellows

28. Halothane
Synthesised in 1951
clinical use - 1956
Enflurane &
Isoflurane
1959-67
Cyclopropane

29. Sevoflurane
1970
Desflurane
1993
Desflurane –
• Fast onset and recovery
• Early awakening facilitates
early neurological evaluation
• Lower concentrations (MAC)
can be used to monitor cranial
nerve function, SSEPs, MEPs
• More profound effect in
increasing CBF & ICP

30. INHALATIONAL AGENTS
DELIVERY SYSTEM
Boyle’s
vapouriser
Boyle’s
Machine

31. VAPOURISERS
TEC vapourisers
Alladin
Vapourisers

32. MODERN INTEGRATED
ANEASTHESIA
WORKSTATION
1. Gas delivery & scavenging system
2. Vapourisers
3. Electronic flow metres
4. Ventilator
5. Monitors
 Lesser fresh gas flows
 Economic usage of inhalational agents
 Sophisticated electronic alarms
 Advanced ventilation modes
 Compact designs, less external connections
 Automated record keeping

33. AIRWAY MANAGEMENT
• Demands in neuroanaesthesia  expertise in the various modes of securing
the airway
• Patient's physiological requirements & unique surgical demands.
• Increased ICP, intracranial aneurysms or arteriovenous malformations.
• Acromegaly and congenital airway difficulties.
• Cervical spine trauma & disorders
• Intra-and postoperative airway obstruction and the timing of postoperative
extubation.

34. McCoy

35. Stylets, bougie, ventilating bougie
Flexitip stylet Video-stylet

36. VIDEOLARYNGOSCOPES
C-MAC
Videolaryngoscope

37. VIDEOLARYNGOSCOPES
King Vision Airtraq

38. FIBREOPTIC BRONCHOSCOPE
• Least cervical spine movement GOLD STANDARD
• Better neurological outcomes compared to other methods
• Needs experience
• Chance for neurologic examination in patients at risk of
secondary cervical injury

39. SUPRAGLOTTIC AIRWAY
• Anticipated/ unanticipated difficult airway
• Inadvertent extubation occurs
• Direct laryngoscopy is impossible 
reestablish oxygenation and ventilation,
even in the prone or lateral position.
• Facilitate fibreoptic endotracheal intubation

40. • Sleep-awake-sleep method
• Stereostatic surgery
• Epilepsy surgery  continuous patient feed-back under conscious sedation 
maximize resection of the seizure focus while minimizing subsequent disability in
nearby motor or language centers of the brain.

41. MONITORING
• Brain can be monitored in terms of
(a) function,
(b) blood flow
(c) metabolism
• General - electrocardiography, direct arterial blood pressure monitoring, pulse oximetry,
end tidal capnography, urine output, temperature, central venous pressure
• Specialised
- Bispectral index ,
- Electroencephalography,
- Trans Esophageal Echocardiography

42. MONITORING OF FUNCTION
• Electroencephalogram
Raw electroencephalogram
Computer processed
Bispectral Analysis
• Evoked potentials
Sensory evoked potentials:
Somatosensory EP
Brainstem auditory EP
Visual EP
Motor evoked potentials
Transcranial electric MEP
Direct spinal cord stimulation
• Electromyography
Cranial nerve functions (V, VII, IX, X, XI, XII)
• Inhalational agents  lower
concentration (0.2-0.5 MAC)
• Total Intravenous anesthesia
(TIVA)
• Dexmedetomidine
Avoid muscle relaxants

43. MONITORING OF FLOW/PRESSURE
• Cerebral blood flow
-Nitrous oxide wash-in
-Radioactive xenon clearance
-Laser Doppler blood flow
-Transcranial Doppler
• Intracranial pressure
-Intraventricular catheter
-Epidural catheter
-Fiberoptic intraparenchymal catheter
-Subarachnoid bolt

44. TRANSCRANIAL DOPPLER
• Non-invasive, continuous measurement
of CBF velocity
• Intraoperatively  velocity in the MCA (Vmca)
• Relative changes in CBF in a quantitative manner, provides a qualitative
assessment of ICP/cerebral perfusion pressure (CPP).
• Occurrence of air or particulate emboli can be detected.
• Used to determine cerebral autoregulation and carbon dioxide (CO2)
reactivity.
• Carotid endarterectomy – detect ischaemia and hyperperfusion syndrome

45. MONITORING OF METABOLISM
Invasive monitor
Intracerebral pO2 electrode (Paratrend, Licox)
• Intraparenchymal electrode reveals regional or local, rather than global, oxygen levels.
pO2 10 mm Hg (threshold for brain hypoxia)
• Restoration  increasing supply of oxygen (supplemental O2, raising CPP, treating
anemia)
 decreasing demand (propofol or barbiturate therapy).
 hyperoxia - absolute or relative cerebral hyperemia d/t loss of cerebral autoregulation.

46. MONITORING OF METABOLISM
Noninvasive monitor
• Jugular venous oximetry - normal Sjvo2 is between 60% and 70%.
• Increased values- Sjvo2 >90%  absolute or relative hyperemia reduced
metabolic need (e.g., a comatose or brain-dead patient) or from excessive flow.
• Decreased values. On the other hand, Sjvo2 is sensitive to global cerebral
ischemia. A value of <50% reflects increased O2 extraction and indicates a
potential risk of ischemic injury
• Transcranial cerebral oximetry (Near-Infrared Spectroscopy)
- measures cerebral regional O2 saturation by measuring near-infrared light
reflected off the chromophobes in the brain -oxyhemoglobin, deoxyhemoglobin.

47. ULTRASOUND
• Transthoracic echo can identify catheters in the SVC- RA junction , detect Venous
air embolism
• Cardiac US imaging – detect ASD/PFO, abnormal ventricular function/ pericardial
effusion
• Vascular US – Screening of deep vein thrombosis
- Safe central venous catheterisation – jugular, femoral,
cubital.
- Confirm tip in SVC
• Lung US – effusion, consolidation, pneumothorax, guiding percutaneous
tracheostomy

48. POSTOPERATIVE
MANAGEMENT

49. ELECTIVE VENTILATION
• Not every patient operated for intracranial pathology requires elective
postoperative ventilation
• Prolonged mechanical ventilation  may exacerbate the postoperative
morbidities
• ICU stay of more than 48 hrs was associated with development of
pneumonia, subsequent increase in hospital stay and poor neurologic
outcome. Mahajan et al Journal of Neuroanaesthesiology and Critical Care | Vol. 1 • Issue 2 • May-Aug 2014
• INDICATIONS - • Pre-op lower
cranial nerve palsy
• Massive blood loss
• Brainstem handling
• Intra-op acute brain
bulge
• Infarct
• Tension
• Residual tumor
• Hematoma
• Prolonged surgery

50. ICU VENTILATORS
Birds ventilator
• Basic features
• Pressure control
• Flow support
Modern ICU ventilator

51. MODERN VENTILATORS  NEWER MODES
• They use ventilatory physics  improve patient-ventilator synchrony
• Assist in weaning and improve outcome.
• Dual control modes(volume assured-pressure support)
• Adaptive support ventilation
• Proportional assist ventilation
• Bi-level airway pressure release ventilation (Bi-PAP)
• Neurally Adjusted Ventilatory Assist (NAVA)
- diaphragmatic electromyography
- parameters – inspiratory time, I:E ratio are patient controlled

52. SEDATION IN ICU
• Benzodiazepines – Midazolam, Lorazepam, Diazepam
• Propofol - usually given continuously,
- awakening occurs in 10-15 minutes even after prolonged sedation.
- reduce cerebral oxygen consumption and lower ICP
- treatment of refractory status epilepticus
• Dexmedetomidine
• Inhalationals
• Neuromuscular Blockers  to facilitate tracheal intubation and
 avoid consequences of coughing and movements on intracranial hemodynamics.

53. ALPHA 2 AGONISTS
Dexmedetomidine –
Concious sedation
dose dependent sedative and anxiolysis
hemodynamic stability
reduces catecholamine levels
 no respiratory depression
non-interference with neurological monitoring

54. Anaesthesia Conserving Device –
• designed to deliver isoflurane and sevoflurane to
mechanically ventilated patients
• Small device placed between ETT & Y-piece

55. POSTOPERATIVE PAIN
• Scalp blocks:
• Regional anesthesia of the nerves that supply sensation to the scalp.
• Local anethetics used  Lignocaine, Bupivacaine, Levobupivacaine,
Ropivacaine
• Combining general anesthesia with a scalp block provides the advantage of
blunting hemodynamic response during particularly stimulating portions of
neurosurgery  head pinning, skin incision & postoperative pain control.

56. ANALGESIA DELIVERY SYSTEMS
Patient Controlled
Analgesia Pump
• Patient presses button for analgesic dose as
and when he experiences pain
• Delivered via IV connected to computerised
pump
• Adjustable dosing , lockout period
• Better pain management than nurse
controlled analgesic administration.

57. WHAT’S DANGEROUS IS NOT TO EVOLVE.
• With the knowledge of advances in neurophysiology,
neuropharmacology and neuromonitoring , neuroanaesthesia is
evolving from its nascent state nearly a half century ago, and further
contributing to better neurosurgical outcome

58. THANK YOU