Tag Archives: drugs

Anaesthesia for the obese patient

Beware of:

‘Apple’ fat distribution (central obesity)

Metabolic syndrome (3 of central obesity, hyper-tension, cholesterol, sugars, lipids)

 

Tips:

Pre-op: STOPBANG >5 = high risk of disordered breathing/OSA

AR: Consider test dose of 50mcg fentanyl pre-induction for sensitivity for opioids

RSI: No evidence

Drug dosing: Ideally use LBW. Practically IBW + few kg. For all drugs except suxamethonium and neostigmine

Position: Reverse trendelenburg with pillow under shoulders for tragus above sternum, rather than break in the bed

Extubation: consider NPA with lidocaine

Post-op: avoid ‘tying’ to the bed e.g. with a-line, infusions

 

Esmolol dosing

Beta1 adrenoreceptor antagonist.

Rapid onset & offset.

For SVT or sinus tachy.

 

Dosing

Infusion +/- loading dose

Loading doses

  • Immediate control: 1mg/kg over 30 sec
  • Gradual control: 500mcg/kg over 1 min

Without a loading dose steady state is achieved after 30min

Infusion

50-200mcg/kg/min (step-wise change every 4 min)

 

 

Asthma

Salbutamol IV

Bolus:
Dilute 1mg into 10ml = 100mcg/ml
Give 250 – 500mcg bolus over 10min
(Paeds 15mcg/kg over 10min)

Infusion:
Conc. 10mcg/ml @ 30-120ml/hr
or 200mcg/ml @ 1.5 – 6ml/hr (paeds: 0.3-0.6 ml/kg/hr. max. 1.5ml/kg/hr)

(Paeds 5mcg/kg/min **???

(INCOMPLETE)

Magnesium IV

1.2 – 2g over 20min (BTS guidelines) *
(Paeds 40mg/kg over 20min)

*in other uses has ben given @ 1g/min.
Attenuates tachycardia of salbutamol. May cause tingling, warmth, flushing, hypotension.

Aminophyline IV

(If not already on it!)

Bolus:
250-500 mg (5mg/kg) over 20min

Infusion:
500-1000mcg/kg/hr

Drugs
Ketamine
Propofol
Sevo
Vec>Roc>atracurim/sux

Ventilation.
Low rate.
Long expiratory pause. (high insp flow rate, low Vt)
Permissive hypercapnia.
(Minimise air trapping/breath stacking)
Consider forced expiration

Time to muscle relaxation for intubation

I tended to attempt intubation prematurely… 3 minutes feels like a long time.  That’s why, when starting at least, the second person came along and stuck the tube down with ease due to the improved intubating conditions i.e. muscle relaxation!  As for sux, if possible, wait for longer than ‘end of fasciculations’ . JC enforces timing 60 seconds!  Especially important in difficult intubations in elective situations.