Pre-Op Investigations / Special Issues

Lab Testing
No longer the 'better safe than sorry' approach of doing many.
- no evidence that performing a standard set improves outcomes (1,2)

Example of Minimal Pre-op Tests for Elective Surgery
ASA I:
1-39yrs : nil, except pregnancy test & CBC if female
40-59yrs: add ECG.
>60yrs: CBC, Na, K, Cr, Urea, Gluc, ECG +/- CXR
ASA II:
- same as above + labs indicated by disease
- could argue for CXR for all smokers with >20pk-yr hx.
ASA III/IV:
- consider med/anaesthetic consult + appropriate work-up.

Patient on anti-platelets
Stop clopidogril 7d earlier; acts on circulating platelets and giving platelets will be pointless.
Aspiring acts on synthesis; 3d washout, 7d better
Do not operate on patients with bare-metal stents for 6m after placement if at all possible; must not stop antiplatelets (heparin / warfarin ineffective in this context)
At least 1y for drug-eluding stents
Else anticipate devastating potential outcomes

Pacemakers
Need a checkup within 6m of surgery
If pacer-dependent or ICD, then within 3m
Diathermy inteference is picked up by pacemakers as cardiac activity and is paced
- this may lead to fatal asystole in pacer-dependent patients
- ICD function may be turned off or it may activate and cause VT / VF
Use harmonic scalpel or bipolar.

Prophylactic cardiac meds?
Have been extensively researched
Beta-blocker initiation peri-op does reduce MI, cardiac morbidity and mortality in at-risk patients
- however increased non-cardiac harm such as stroke, and overall, worsens outcome; No role
Statins probably reduce risks but prospective studies are lacking

Glucose control
Intensive glucose control peri-op decreases complications (e.g. infxs) and improves outcomes and LOS
Surgical / illness stress --> cortisol, GH, epinephrine --> high BSL even in non-diabetics
Mortality significantly reduced in critically ill patients especially with tight glucose control