Anaesthetics

Question 1

Summarise the General anaesthesia triad and what drugs are commonly used

Answer 1

Triad: Analgesia (Fentanyl, remifentanil, morphine); hypnotics (propofol, ketamine, thiopental, sevoflurane, NO); muscle relaxation (depolarising: suxmethonium; non-depolarising: rocuronium)

Question 2

How long is fasting required for before an operation - why?

Answer 2

Fasting: 6 hrs of no food and 2hrs NBM is needed to prevent aspiration pneumonitis/ pneumonia

Question 3

What is done before induction of anaesthesia?

Answer 3

Pre-oxygenation: So the patient has a reserve of oxygen whilst they are being successfully intubated and ventilated

Pre-medication: May be given to relax patient e.g. benzos, opiates

Question 4

What is a RSI? What are its indications?

Answer 4

RSI: Reqiores cricoid pressure to prevent aspiration

Indicated: Airways needs quick securing: Emergency, GORD, pregnancy

Question 5

What anti-emetics are used in anaesthesia? What are their CI?

Answer 5

Ondansetron (5HT3 receptor antagonist) – avoid in prolonged QT interval

Dexamethasone – caution in diabetic or immunocompromised

Cyclizine (histamine (H1) receptor antagonist) – caution with HF and elderly

Question 6

How is anaesthetic worn off?

Answer 6

Check muscle relaxant worn off via a nerve stimulator eg ulnar nerve for thumb twitching - can reverse muscle relaxant if needed

Then stop the anaesthetic and extubate

Question 7

What are the risks of general anaesthesia?

Answer 7

PONV common 
Waking during anaesthetic
Aspiration
Dental injury
Anaphylaxis
CVS event 
Malignant hyperthermia

Question 8

What is malignant hyperthermia

Answer 8

Hypermetabolic response to voltaile anaesthics/ suxamethonium

Sx: Hyperthermia, increased CO2 output, tachycardia, muscle rigidity, acidosis, hyperkalaemia

Mx: Dontrolene

Question 9

What are the other types of anaesthetic?

Answer 9

Peripheral nerve block

Spinal block (into CSF in subarachnoid) - often used TURP, c-section and hip #s

Epidural - labour

Local anaesthetic - sutures, dermatology, dental, hand surgery, LP, central line, PCI

Question 10

What are the indications for a tracheostomy?

Answer 10

Respiratory failure where long term ventilation is required

Weaning from mechanical ventilation

Upper airway obstruction eg tumour/ head and heck surgery

Respiratory secretion management eg in paralysis

Reducing aspiration risk e.g. in unsafe swallow/ absent cough reflec

Question 11

What is a central line vs PICC line vs Hickman line vs portacath?

Answer 11

Central line aka central venous catheter is inserted into the internal jugular/ subclavian/ femoral and the tip lies in the VC. It is used for taking blood and giving medications - some medications can only be given centrally eg inotropes, amiodarone or high potassium

PICC line is a type of central venous catheter that is inserted through a peripheral vein and fed into a central vein eg VC or RA

Hickmann line is a tinnelled central venous catheter. It enters via the SC tissue into the subclavian/ jugular vein and sits in the SVC/ RA. it has a cuff to prevent infection and allow it to be long term for chemo/ haemodialysis

A portcath is a hickman without the cuff so the skin remains in tact, any medications must be given via a needle through the skin into the port. Used for chemo usually.

Question 12

What are the aims of post-operative analgesia

Answer 12

Encourage patient to: mobilise, ventilate lungs and have adequate oral intake

Question 13

What are some common reasons for ICU admissions?

Answer 13

Major trauma
Major surgery eg AAA
Severe sepsis 
CPR 
Organ failure

Decision is made by specialists and may use scoring systems eg APACHE, SAPS

Question 14

What nutritional support do ICU patients need?

Answer 14

Since are in a hypermetabolic stte need high calories. Can be given enteral eg nouth, NGT, PEG or TPN where is given via central line

Question 15

What are some complications of being admitted to ICU?

Answer 15

Ventilator-associated lung injury –> damage due to inflmmation/ pressure changes/ overinflation alveoli –> pulmonary fibrosis/ cor pulmonale

Ventilator associated pneumonia

Catheter related infections

Stress related mucosal disease - prevent with PPI and early trophic NGT feeds

Delirium

VTE - prevent with LMWH and intermittent pneumatic compression

Critical illness Myopathy - wasting due to lying still/ steroids/ muscle relaxants –> Can lead to difficulty weaning off ventilation and has impacts for QOL

Question 16

What do the different ABG readings mean?

Answer 16

Resp Acidosis: retaning CO2

Resp Alkalosis: Hyperventilating due to anxiety or PE - PE will have low O2 whereas hyperventilation will have high O2

Metabolic alkalosis: Vomiting due to loss H+, excess aldosterone which excretes H+ eg conns, liver cirrhosis, HF, diuretics

Metabolic Acidosis: Raised lactate,
ketones,
high H+ eg renal failure/ rhabdomyolysis/ renal tubular acidosis
Low bicarb eg diarrhoea, renal failure or renal tubular acidosis

Question 17

What is PEEP and how can it be given?

Answer 17

Positive end-expiratory pressure is additional pressure at the end of exhalation to stop the airways from collapsing- reduces atelectasis and effort for breathing, increases gas exchange

Can be given via: High flow nasal cannula, NIV, mechanical ventilation

Question 18

What is the difference between CPAP and BiPAP?

Answer 18

CPAP is constant pressure to keep the airways expanded by adding PEEP to stop collapse

BiPAP is a cycle of adding high and low pressure - uses IPAP and EPAP

Question 19

What is the MAP? How is it calculated?

Answer 19

Mean arterial pressure (MAP) is the average blood pressure throughout the entire cardiac cycle, including both systole and diastole. If it is too low there will be tissue hypoperfusion

MAP = CO x systemic vascular resistance. CO = SV x HR

Question 20

What are inotropes?

Answer 20

Positive = Increase contractility of the heart e.g. catecholamines that work via SNS - adrenaline, dobutamine, noradrenaline –> must be given through central venous catheter

Negative= BB, CCB, flecainide

Question 21

What are vasopressors?

Answer 21

Increases systemic vascular resistance –> increase MAP

Examples: noreadrenaline, vasopressin (ADH), adrenaline, metaraminol, ephedrine

Question 22

What are the indications for dialysis?

Answer 22

Acidosis 
Electrolyte abnormalities
Intoxication
Oedema
Uraemia

Question 23

How does haemodialysis work?

Answer 23

Blood is taken out of body into the dialysis machine along a semi permeable membrane. Solutes filter out the blood and across the membrane into the dialysate.

In an acute setting access is gained with a Vas Cath ( central venous cathter)