EBS – Hyponatraemia following elective cerebral aneurysm clipping

Anthony Chau

EBS, Feb 2015

Clinical case scenario

• 55F, ICU nurse

• B/g coronary artery spasm, HTN, non-smoker

• Left incidental paraophthalmic ICA aneurysm

• Left OZ craniotomy and clipping

• Postop CSW (then DI, then CSW +/- SIADH)

Clinical context

• Why is hyponatraemia important to detect?

• Aneurysmal SAH and hyponatraemia

Hx of CSW and SIADH

PICO question

• P: adult patients with unruptured intracranial aneurysms

• I: elective clipping

• C: nil

• O: incidence and time period of postoperative hyponatraemia (at the index admission)

Approach

• Wanting a quick and specific answer, at the expense of a sensitive high volume search

• Assume that data will come from observational studies

– Lots of ‘noise’ expected from case reports, expert commentary and literature reviews

• Happy to include data from English abstracts from papers not in English

Al-Dwairy diagram

Who? [P] What? [I]

Then what? [O]

Adult patients with unruptured intracranial aneurysms

Elective clipping

Postoperative hyponatraemia

Population circle

NOT

Intervention circle

Outcome circle

Al-Dwairy diagram

Who? [P] What? [I]

Then what? [O]

Intracranial aneurysmNOTChild or SAH

Neurosurgical proceduresANDAneurysm Clipping

Postoperative complicationsANDHyponatraemia, Inappropriate IDH syndrome

Additional amendments:- Allow for US/ UK spelling- Increase sensitivity of MeSH concepts by adding common terms and searching under .mp

Search Filter

Results – Medline (via OVID)

Medline (OVID) – attempt 2

Medline (OVID) – Attempt 3

Medline – attempt 4

Scopus (1)

Scopus (2)

Google Scholar search

• Key terms (various combinations tried):

– “Hyponatraemia” or “hyponatremia”

– Aneurysm

– Surgery or clipping

– Elective or unruptured

Results

Medline 230 articles

Scopus 100 articlesGoogle ~50 articlesCross-referencing

320 abstracts reviewed

25 full text articles retrieved

Excluded 295:- Not relevant to clinical question: 226- Review article/ case report: 67

Excluded:- Hyponatraemia not mentioned or evaluated: 22- Unable to separate elective vs emergency surgery: 3

3 articles for qualitative review

ResultsAuthor (year) Country Population No. Pts Incidence (%) Timing

Wirth (1983) US Ant + post circulation, 40-70yo, up to 25mm size 107 1 (1%) -

Rice (1990) Canada Posterior circulation, 16-75yo, mean, up to 25mm size 167 5 (3%) -

Pereira-Filho (2010) Brazil Anterior circulation, 21-70yo, mean 7mm size 40 1 (3%) -

Clinical significance not stated

In retrospect…problems with this search strategy

• Negative search terms excludes relevant studies– Excl “SAH” or “ruptured” omits studies evaluating both elective and

emergency clipping

– Excl “endovascular” omits studies evaluating both clipping and coiling

• Hyponatraemia not a key word, and does makes it into abstracts– Hence broad term such as “exp Postoperative complications/” req’d

– Only way to counter this, is via a highly sensitive search strategy, ie look at all studies involving elective (and therefore, those which inclemergency) clippings, and manually look for hyponatraemia• But huge body of literature

Al-Dwairy diagram

Unruptured aneurysms

Elective surgery

Postoperative hyponatraemia

Other observations

• Hyponatraemia not a commonly reported complication after elective aneurysm surgery– ?Not common and/or clinically unimportant

– If not reported, could be that incidence is 0%, or (more likely) that it was not a parameter of the study

– Even the landmark ISUIA study (Lancet, 2003) with 1917 elective aneurysm clippings, does not mention hyponatraemia