ANZCA EXAM Q 1996A06--neuroanesthesia

shenxiu2

1996A06:   A previously well 38 yo man presents for urgent clipping of a middle cerebral artery aneurysm.  He has photophobia, and a blood pressure of 150/90

Outline how you would manage post-operative vasospasm in this patient

General Measures

•        Ensure adequate patent airway and avoid hypoxaemia
•        Monitor in intensive care unit.
o        CVP
o        invasive arterial pressure recording
o        Regular monitoring of neurological state is essential.

Specific Measures to increase perfusion:

•        Triple H therapy – mainstay of mx since 1970s – prospectively shown to reduce morbidity and mortality from vasospasm ~20% (1980s) to 5-10% although RCT data not available.

o        Hypervolaemia:
        Volume load with colloid (eg 5% Albumin or Gelofusine)
        NS may be used (glucose and low sodium containing solutions are avoided)
        Problems with pulmonary oedema, worsening cerebraloedema, myocardial ischaemia, haemorrhagic infaction
        Only one prospective study supports use
        Outcomes with hypervolaemia vs. normovolaemia compared in 1999 with RCT – no difference in global cerebral blood flow
        Many patients with SAH present hypovolaemic – it is felt that this is more important to prevent
        CVP aim usually 8-10 cmH2O

o        Haemodilution
        Eg Hb < = 11 g/dL

o        Hypertension
        Prior to aneurysm clipping aim for SBP < 110 mmHg or within 20% of baseline
        Post – clipping: usually 20-30% above baseline – eg 150-170 mHg
        may require the use of inotropic support e.g. low dose adr, NA

•        calcium channel blockade - nimodipine is the drug of choice ( 60mg 4/24 for 21 days). Fausidil HCl is an alternative.
o        shown to reduce the incidence and severity of vasospasm.
o        mechanism remains unclear; possible vasodilation by calcium channel block, or free radical scavenging.
o        Should be given either as IV infusion with accompanying flushing solution through a central line, or can be given orally three times per day.
o        Should be commenced early in the management.
o        Nicardipine has failed to show benefit