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Aneurysmal subarachnoid haemorrhage and the anaesthetist

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Aneurysmal subarachnoid haemorrhage and the anaesthetist Powered By Docstoc
					      Aneurysmal subarachnoid
   haemorrhage and the anesthetist
                          H.-J. Priebe
Department of Anaesthesia, University Hospital, Hugstetter Str. 55,
                  79106 Freiburg, Germany




             British Journal of Anaesthesia 99 (1): 102–18 (2007)
                  Epidemiology and etiology

Incidence : 1년에 100,000명당 8~10건.
주로 55세~60세에 호발
Stroke의 5~15%가 Ruptured intracranial An.
약 3/4 의 SAH는 ruptured cerebral An.에 의해 생긴다.
Giant aneurysm : > 2 cm
Cerebral An.의 발생 원인
1) genetically, hemodynamically, nicotine abuse- or alcohol abuse-induced
   structural defect
2) chronic hemodynamically-induced intravascular shear stress 의 복합적 요인
   ( An. out-pouchings in the subarachnoid space at the base of the brain)
3) Infections or trauma.
Aneurysms 호발 부위
: turbulent flow가 잘 발생하는 vascular bifurcations에 주로 위치
(80~90%) the anterior (carotid) circulation, the anterior and
            posterior communicating, and the middle cerebral artery
(10~20%) posterior (vertebro-basilar) circulation.
                     Pathophysiology
An.의 Rupture시, intra-arterial and subarachnoid spaces사이에 free
 communication exists가 존재.
The sudden increase in regional intracranial pressure (ICP) 의 갑작스러운
 증가로 severe headache and (transient or permanent) loss of
  consciousness를 야기.
Subarachnoid space로의 blood spread로 인해
   headache, meningism, hydrocephalus를 야기한다.
Recurrent episodes of bleeding, blood clots and adhesions으로 인해
  subarachnoid space를 통한 spread of blood 방해로 인하여
  Intracerebral hematomas 형성.
Subarachnoid space의 blood로 인해 cerebral vasospasm이 생긴다.
Blood의 양과 위치가 incidence of cerebral vasospasm과 연관.
ICP증가의 원인 : 1) expanding mass effect of the hemorrhage
            2) development of brain edema
            3) obstructive hydrocephalus
Autoregulation of cerebral blood flow (CBF)
SAH는 CBF와 cerebral metabolic rate (CMR)의 감소가 동반된다.
자주, cerebral autoregulation의 손상이 나타난다.
손상의 정도는 neurological condition과 연관되어있다.
이는 low blood pressure로 인해
   Cerebral perfusion pressure (CPP)가 낮아져
   neurological deficits정도가 높기 때문에
   수술 중 혈압 낮추는 것은 논쟁의 여지가 있다.

Cerebrovascular CO2 reactivity
SAH 발생시, arterial carbon dioxide (CO2)의 변화로 인해
  cerebrovascular reactivity가 유지된다.
CO2 reactivity가 손상되는 경우 poor neurological condition을 보인다.
대부분의 SAH시, hyperventilation이 increased ICP의 치료의 option으로 주
   어진다.
                   Natural history

SAH 의 사망률 : 50%.
Aneurysmal SAH의 30 day mortality : 45%.
1/3 of survivors remain moderately to severely disabled.
약 10%의 SAH환자는 죽기 전에 많은 수가 comatose, severe neurological
 deficits를 갖는다.
SAH발생 후, re-bleeding and cerebral vasospasm은 3주 내에 발생.
Ruptured An.은 첫 24h동안에 2-4%에서, 첫2주안에 15–20% re-bleed 발생.
                 Clinical presentation
Symptoms :
 1)   sudden onset of severe headache
 2)   meningism
 3)   loss of consciousness (transient or persistent)
 4)   epileptic seizures
 5)   focal neurological deficits
Neurological injury :
 1)   unconsciousness
 2)   depressed consciousness
 3)   focal neurological deficits
 4)   isolated cranial nerve palsy
감각의 둔화와 non-reactive small pupils가 특징적이다.
50%에서 hydrocephalus의 non-specific findings이 보여진다
Standardize clinical assessment and to estimate the prognosis
  1) Clinical grading scales such as the one of Hunt and Hess
  2) the World Federation of Neurological Surgeons
      Hunt and Hess grading scale for SAH

Grade                   Clinical description
-------------------------------------------------------------
I      Asymptomatic or minimal headache and slight nuchal rigidity
II     Moderate to severe headache, nuchal rigidity, no neurological
         deficit other than cranial nerve palsy
III    Drowsiness, confusion, or mild focal deficit
IV     Stupor, moderate to severe hemiparesis, and possibly early
          decerebrate rigidity and vegetative disturbances
V      Deep coma, decerebrate rigidity, and moribund appearance
    World Federation of Neurological Surgeons
        Grading Scale for aneurysmal SAH

.   Grade        GCS score          Motor deficit                               .




     I             15                 Absent
    II           13 or 14             Absent
    III          13 or 14             Present
    IV             7–12           Present or absent
    V              3–6            Present or absent
                                                  * GCS : Glasgow Coma Scale.


Higher clinical grade의 의미 :
   cerebral vasospasm, elevated ICP,
   impaired cerebral autoregulation, impaired vascular CO2 reactivity,
   cardiac arrhythmias and dysfunction, hypovolemia,
   and hyponatremia.
                           Diagnosis

SAH는 여러 복합적인 증상을 갖기 때문에 severe headache, lasting for longer
    than an hour with no alternative explanation 환자의
   경우 SAH를 r/o 해야 한다
Initial diagnostic tool of choice : Unenhanced cranial CT
SAH발생시 10일안에 재 흡수되기 때문에
 sudden severe headache and immediately impaired consciousness 발생시
 즉각적으로 CT를 촬영 해야 한다.
The amount of blood on unenhanced CT can be described by the Fisher
    four-point scale.
CT상 blood의 위치와 분포는 SAH의 원인을 알아내는데 도움이 된다.
Additional investigations :
    Lumbar puncture, Multi-slice CT angiography,
    Four-vessel catheter angiography, spinal catheter angiography, MRI
SAH의 진단 후, 다음 단계는 An.의 rupture여부
              Fisher grading scale
  of cranial computerized tomography (CCT)


Grade                        Findings on CCT                          .
  1        No subarachnoid blood detected
  2        Diffuse or vertical layers <1 mm
  3        Localized clot and/or vertical layer >1 mm
  4        Intracerebral or intraventricular clot with diffuse or
             no subarachnoid haemorrhage
* the best predictor of cerebral vasospasm and overall patient outcome.
              Major complications of SAH

Re-bleeding, cerebral vasospasm leading to immediate and delayed
         cerebral ischemia, hydrocephalus,
         cardiopulmonary dysfunction,electrolyte disturbances.

Non-neurological complications of SAH
(e.g. anemia, hypertension, hypotension, hyperglycemia, electrolyte
   disorders, cardiac insufficiency, and arrhythmias)
      Complications of aneurysmal SAH.

Re-bleeding   On day 1: 15%
              By 1 month: 40%
              After 6 months: 3% per year
Cerebral ischemia
Immediate onset (increased ICP resulting in decreased CPP)
Delayed onset (peaks 4–14 days after SAH)
Seizures
Hydrocephalus (in 15–20% of cases)
Cardiac dysfunction
 (reflected by echocardiographic abnormalities and by
   increases in serum concentration of cardiac troponin)
Hyponatraemia, hypomagnesaemia or both (because of salt wasting)
Cerebral vasospasm
 Cerebral vasospasm : 60–70%정도 발생, 3–12일 후에 나타나며 2주정도 지속.
 Cerebral vasospasm -> cerebral ischemia
    : major cause of morbidity and mortality after SAH.
 Severe cerebral vasospasm은 infarction and death를 야기 (SAH환자의1/3)
 Dx.: angiographly
 ICP증가와 hypovolaemia는 cerebral vasospasm을 증가시킨다.
 Cerebral vasospasm은 또 ICP를 증가시킨다
Cardiac dysfunction
marked systemic and pulmonary hypertension, cardiac arrhythmias,
   myocardial dysfunction and injury, and neurogenic pulmonary edema를
   동반.
ECG abnormalities : QTc prolongation, repolarization abnormalities
Cardiac injury and dysfunction은 직접적으로 morbidity and mortality
Electrolyte disturbances
Hyponatraemia, hypokalaemia, hypocalcaemia, hypomagnesaemia
      Prophylaxis and therapy of cerebral
                  vasospasm
Nimodipine
Mild sedation
Positive fluid balance
Avoidance of hypotensive episodes
Hyponatremia.
Symptomatic treatment of cerebral vasospasm
Triple-H therapy
Balloon angioplasty
Intra-arterial papaverine.
Nimodipine
Calcium channel blocker
Improves outcome after SAH
Thrombophlebitis발생가능( peripherally투여시)
 : 반드시 central venous catheter로.
Infusion system : protected from light.
Triple-H therapy
Triple-H therapy : hypertension, hypervolaemia, and haemodilution
Ix. 1) Transcranial Doppler velocities (as a reflection of cerebral
        vasospasm)이 증가된 환자
    2) the development of neurological deficits인 환자에서 시행
Therapeutic goal of triple-H therapy
   Increase CBF, Increase CPP
120–150 mm Hg in unclipped
160–200 mm Hg in clipped aneurysms ;
CVP: 8–12 mm Hg정도로 유지
Hematocrit 0.3–0.35
Complications of triple-H therapy
1) pulmonary edema           2) myocardial ischemia
3) respiratory insufficiency 4) hyponatremia
5) indwelling catheter-associated morbidity
Balloon angioplasty
Ix. medical tx.에 반응하지 않은 상태로 새로운 신경학적 손상이 있을 경우
Cx. dissection, rupture, and thrombosis of the cerebral artery
    with subsequent cerebral infarction or hemorrhage.

Intra-arterial papaverine
Vasospasm이 more distal vessel segments에 있을 경우,
intra-arterial administration of papaverine may be more effective
(maximally 300 mg per hemisphere).
Relatively short acting, 가끔은 반복적인 치료를 필요로 한다.
Neurotoxic하여 seizures, coma, blindness, irreversible brain injury가능성
Radiography상 항상 향상되어지지는 않으며 triple-H therapy보다 많은 효과
    적인지도 의문.
     Occlusion therapy of cerebral aneurysm

surgically (‘clipping’) or endovascularly by detachable coils (‘coiling’).

IX. Based on patient age,
    World Federation of Neurological Surgeons grade
    Co-morbidity, SAH onset time, and the anatomy of the aneurysm.

Rationale for early intervention
  prevention of re-bleeding
  Reduction in the incidence of cerebral vasospasm
  by the removal of blood from the subarachnoid space.

All ruptured aneurysms in patients with Hunt and Hess grades I–IV are
    generally treated within 72 h.

Controversy exists as how to proceed in patients with grade V.
Procedural risks
Clipping
Procedural morbidity (4.0–10.9%) & mortality (1.0–3.0%)
Intraoperative leak and frank rupture of aneurysms 발생률 : 6-13%.
Coiling
Procedural morbidity (3.7–5.3%) & mortality (1.1–1.5%)
Major Cx. : arterial dissection, parent artery occlusion
            thromboembolism, rupture of the aneurysm
Minor CX. : Reaction to contrast material, groin haematoma,
            infection, pseudo-aneurysm.
Limitations of coiling
Large aneurysms or aneurysms with wider necks,
Occlusion of the aneurysm with coiling상태
Clipping vs coiling
Coiling : Minimally invasive Tx., more safer,lower perioperative risk.
Complete occlusion 비율
   : surgically group VS endovascular group (82 vs 66%)
Re-bleeding occurrence
   : surgically group VS endovascular group (41 vs 52%)
Perioperative anaesthetic
      management
     Perioperative anaesthetic management
                              Preoperative evaluation & Premedication

Preoperative evaluation
고려 해야 할 점 >
 1) Electrolyte disturbances로 인한 ECG변화 가능성
    (prolonged QT-interval, abnormal T-wave, and arrhythmias)
 2) Myocardial injury
    ( ST-segment elevation or depression, Q-waves, and arrhythmia)
 ->적절한 진단과 치료가 필요
SAH환자의 경우 ECG의 변화는 cardiac origin이기 보다는 neurological
damage완 연관된 neurogenic origin이다
SAH 환자중 cardiac troponin의 증가가 보일 경우 myocardial cell injury를
  나타내며 예후는 나쁘다
Underlying cardiac impairment가 있는 경우 coiling이 선호

Premedication
No drug can be considered the drug of choice in all situations
Anxiety로 인한 투여의 경우 respiratory depression을 야기
(causing an increase in PaCO2 followed by an increase in ICP
     Perioperative anaesthetic management
                                       Monitoring & ICP monitoring

Monitoring
Standard monitoring
 1) 5-lead ECG, continuous
 2) Intra-arterial pressure
 3) Pulse oximetry
 4) Capnography
 5) Urinary output
 6) Body temperature
 7) Neuromuscularblock.
  * Insert a central venous catheter :
     (1) Guidance of intravascular volume
     (2) For the injection of potent cardiovascular drugs
     (3) For administration of mannitol
       (smaller peripheral vein으로 투여 시 local inflammation가능성이 있다.)

ICP monitoring
Poor clinical grade or hydrocephalus한 경우
     Perioperative anaesthetic management
         Neurophysiological monitoring & Jugular venous bulb monitoring

Neurophysiological monitoring
Cerebral function의 monitoring
  1) Cortical somatosensory-evoked potential (SSEP)
         : Both ant. or post. cerebral circulation수술 시
   2) Brainstem auditory-evoked potential (BAEP)
         : vertebral-basilar circulation수술 시
Combined SSEP and BAEP monitoring 은
           false-positive & false-negative를 낮춘다
Detection of cerebral ischemia by evoked potential monitoring
  (removal or replacement of a vascular clip시 측정)
Evoked potential monitoring : High-dose barbiturates사용시 억제
                                specificity가 낮다
 이러한 제한 점으로 인해 routine monitoring 은 아니다
 neurophysiological monitoring사용시 i.v. anaesthesia가 choice
Jugular venous bulb monitoring
Cerebral venous oxygen saturation의 monitoring
Cerebral ischaemia의 the early recognition
Temporary occlusion시 artery feeding과 collateral perfusion여부 확인
     Perioperative anaesthetic management
                                       Brain relaxation & Mannitol

Brain relaxation
목적> Adequate CPP
    Avoid hypotension and hypertension,
    Maintaining normoventilation
    Adequate oxygenation
Mannitol
Peak effect of mannitol on ICP and brain bulk : 약30–45 min
Clinical effect의 판정 : (urine output의 측정보다) ICP에의 반응여부
Early reduction in ICP는 preserved autoregulation을 나타냄
Rapid infusion : transient hypotension 야기
Slow infusion : 혈압은 20%이상 올라가지 않는다.
Mannitol은 renal Insufficiency 환자의 경우
   일시적으로 hematocrit의 감소, serum osmolality의 증가되어
   hyponatraemia, hyperkalaemia, and metabolic acidosis가 생길수 있다.
Recommended dose : 0.25 ~ 2 g/ kg(Usually,0.5–1.0g/ kg)
Dose and speed of infusion은 underlying clinical circumstances를 보고 판단
     Perioperative anaesthetic management
                                        Furosemide & Drainage of CSF

Furosemide
Alternative to mannitol.
Dose : alone at high dose or Combination with mannitol at lower dose
ICP감소 & brain water content감소
Mannitol투여 전 furosemide의 투여는 mannitol으로 인한 초기 ICP상승을 둔화
Combination하는 것이 각각의 약을 따로 쓰는 것 보다
      ICP와 brain bulk에의 therapeutic effect가 넓다.
Drainage of CSF
성인의 CSF양은 약150 ml
Lumbar subarachnoid or ventriculostomy catheter
Catheter거치 후 acute drainage of a large volume of CSF를 피해야 한다
 : abrupt decrease in ICP and brain ‘sagging’.
    aneurysm의 re-bleed, and intracerebral haematoma
    reflex hypertension, bradycardia등이 생길 수 있다.
CIx. intracerebral haematoma환자( risk of brainstem herniation)
이론적으로, CSF drainage는 dura를 열기 전에 투여되면 안 된다.
그러나 임상적으로 신경외과 의사는 dura 열기 전에 상태를 좋게 하기 위해
CSF drainage를 시도한다.
       Perioperative anaesthetic management
                                               Miscellaneous interventions

Miscellaneous interventions
1)   Adequate ventilation & oxygenation
2)   CPP and acid–base status
3)   Unobstructed cerebral venous return (check the patient’s head position)
4)   Drainage of CSF

Mild hyperventilation : PaCO2 30–35 mm Hg before opening the dura
                        PaCO2 25–30 mm Hg during opening the dura
Bolus dose of thiopentone (approximately 2–3 mg /kg)
                               for its cerebrovasoconstrictive property.
  효과가 있다면, continuous infusion of thiopentone (4–5 mg/kg/h)투여
  그러나 awakening이 delay될 수 있다.
     Perioperative anaesthetic management
                                         General principles of anesthesia

General principles of anesthesia
(1) Control of the TMPG (transmural pressure gradient) of the aneurysm
(2) Preservation of adequate CPP and oxygen delivery
(3) Avoidance of large and sudden swings in ICP
(4) Providing conditions
     that allow optimal surgical exposure with least brain retraction
(5) Allowing rapid awakening of the patient
Risk of rupture of aneurysm
  : By dangerous increase in the TMPG of the aneurysm
 (1) Laryngoscopy , Tracheal intubation
 (2) positioning of the patient placement of the pin head-holder
 (3) raising of the bone flap
Prophylactic administration of bolus doses
: 자극에 대한 반응을 둔화시켜 hypertensive response의 가능성을 낮춘다
  (1) anesthetic drugs
    (e.g. propofol or thiopentone before placement of the pin head-holder)
  (2) cardiovascular depressant drugs
    (e.g. esmolol or labetalol before laryngoscopy and tracheal intubation).
*ultra-short-acting opioid, remifentanil의 사용으로 potent stimulation를 낮춘다.
     Perioperative anaesthetic management
                                           Choice of anesthetic drug

Choice of anaesthetic drug
* Avoid hypertensive episodes and ensure adequate CPP
 physiological ICP and optimal brain relaxation을 유지

Volatile anesthetics : direct cerebral vasodilatory effects
1 MAC까지 CBF를 비교적 유지 (metabolic rate의 감소로 CBF감소)
Opioids는 일시적으로 ICP를 증가시킨다.
Etomidate : least cardiovascular side-effects compared with other drugs
            (decrease ICP while preserving CPP)

sensory-evoked potential 측정 시에는 total i.v. anesthetic가 선호
     Perioperative anaesthetic management
                      Management of CPP and TMPG of the aneurysm

Management of CPP and TMPG of the aneurysm
CPP and TMPG of the aneurysm.
CPP = MAP – ICP
TMPG of the aneurysm : MAP – ICP
(the pressure within the aneurysm (equal to MAP)
        - the pressure outside the aneurysm (equal to ICP))
TMPG가 작을수록 risk of aneurysm rupture가 감소한다.
CPP가 높을수록 cerebral oxygenation이 유지된다.
Risk of inadequate cerebral perfusion과 rupture of the aneurysm가능성
   의 균형을 맞추는 딜레마가 생긴다.
이상적으로는, 거의 얻기는 힘들지만, CPP와 TMPG of the aneurysm은
   preoperative baseline values를 유지하는 것 이다.
     Perioperative anaesthetic management
                                              Induction of anaesthesia

Induction of anaesthesia
goals
(1) prevention of rupture of the aneurysm,
(2) preservation of cerebral oxygenation
(3) prevention of an increase in ICP

* Blunt the hypertensive response to laryngoscopy and tracheal intubation
  (e.g. esmolol, labetalol, and i.v. lidocaine)
* Deep level of anesthesia
  ( high doses of anesthetic drugs or monitoring of depth of anesthesia)
* Continuous infusion of a vasopressor
  (phenylephrine or norepinephrine)
    Perioperative anaesthetic management
                   Respiratory management & Induced hypotension

Respiratory management
Normoventilation이 목표
가능하면 N2O를 제외하고, CO2의 cerebrovascular reactivity를 유지
Prolonged hyperventilation -> cerebral ischemia발생 가능
Transient and moderate hyperventilation는 ICP가 증가된 경우에만 고려
Induced hypotension
Systemic arterial pressure의 감소는
  TMPG of the An.와 wall stress of the An.을 감소시킨다.
이는 clipping of the An. & rupture of An.시 bleeding control에 도움을 준다
Induced systemic hypotension은 특히 hypovolemia일 경우
   cerebral perfusion을 악화 시킬 수 있고
   higher incidence of severe cerebral vasospasm이 생길 수 있다.
Duration of temporary occlusion : 15–20 min이 넘지 않도록
   (decrease in brain PO2 and an increase in brain PCO2)
     Perioperative anaesthetic management
            Induced hypothermia & Pharmacological brain protection


Induced hypothermia
임상적으로 약간의 hypothermia를 유지한다.
이는 beneficial effect는 가지지 못한다.
Giant An. (>2 cm)는 (특히 brainstem가까이에 있을 경우)
   Cardiopulmonary bypass를 이용하여 complete circulatory arrest와
   profound hypothermia를 일으킨다.

Pharmacological brain protection
barbiturate or propofol :prophylactically administration
                         EEG burst suppression
     Perioperative anaesthetic management
                                      Prophylaxis of cerebral vasospasm

Prophylaxis of cerebral vasospasm
  Fluid management
수술 전 cerebral vasospasm이 없고 good clinical grade면, normovolaemia를 유지
약간 baseline MAP보다 높은 것도 postoperative cerebral vasospasm을 줄이는데
  도움이 된다.
수술 전 cerebral vasospasm이 있는 경우, volume loading시 invasive monitoring
  하는 것이 낫다 (transoesophageal,echocardiographic monitoring)
수술전 hypertension이 있던 환자는 MAP를 comparable level로 유지하고,
  intraoperatively induced hypotension은 relatively contraindication이다.

  Papaverine
After clipping of the An. & before closure of the dura
: preventing cerebral vasospasm.
Cx. : mydriasis
      facial nerve palsy,
      signs and Sx. resembling malignant hyperthermia
      bradycardia and hypotension
      cerebral vasospasm(rarely)
     Perioperative anaesthetic management
                                                              Recovery

Recovery
술 후, 환자는 여러 진단과 치료의 접근이 가능하게
구두 명령에 반응하여 빠른 신경학적 평가가 가능하게 해야 한다.
Rapid and smooth awakening을 필요로 한다.
Emergence시간이 지체되거나 새로운 신경학적 장애가 발견되면,
 CT or angiography를 통해 intracerebral haematoma or occlusion of a
   blood vessel여부를 r/o해야한다.
수술전보다 술 후 혈압이 20–30%정도 올라가면
    intracranial hemorrhage나 edema의 가능성이 있다.
HTN의 예방을 위한 약제 투여
 : analgesic, anti-emetic, anti-shivering or anti-hypertensive drugs
Hunt and Hess grades III or IV or intraoperative complications인 경우
 : 수술 후 즉각적인 extubation을 피해야 한다
Critically ill patients
 : 술 후 intensive cardiopulmonary and general supportive care가 필요
   Stupor or comatose 환자의 경우 초기에 tracheotomy하는 것도 고려

				
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