Perioperative Management Flashcards
Why is smoking history important pre-op?
When was their last cigarette? It constricts the airways and makes them hyper-reactive so they may go into bronchospasm more easily
Also heavy smokers may not know they have COPD so take care giving O2 to wake them up
What are the main aspects of physical examination pre-op?
Airway assessment
CVS
Respiratory
What is ASA grade 1?
Normal healthy patient
What is ASA grade II?
Patient with mild systemic disease and no functional limitations
What is ASA grade III?
Moderate to severe disease that results in some functional limitations
What is ASA Grade IV?
Severe systemic disease that is a constant threat to life and functionally incapactitating
What is ASA grade V?
Moribund patient not expected to survive 24 hours with or without the surgery
What does E after ASA grade mean?
That the procedure is an emergency
What investigations are performed routinely at pre-assessment?
Urinalysis ECG if >50y FBC Blood glucose in diabetics Pregnancy test for all females of reproductive age U&Es if >60y Coagulation, group&save
What are the time limits in NBM?
Clear fluids up to 2 hours before procedure
Light meal 6 hours before
What does -plasty mean at the end of a surgical procedure?
Surgical refashioning to regain good function
What does -stomy mean?
Artificial Union between a conduit and another conduit/the outside world
What is a cyst?
Fluid-filled cavity lined by epi/endothelium
What is colic?
Intermittent pain from over-contraction or obstruction of a hollow viscus
What is a sinus?
Blind-ending tract
Typically lined by epithelial or granulation tissue, which opens to an epithelial surface
What is an ulcer?
Interruption in the continuity of an epi/endothelial surface
What are the aims of preoperative assessment?
Know planned procedure
Improve any comorbidities which may increase risk of an adverse outcome
Anticipate potential problems
Informed consent
Appropriate prophylactic measures and premedication
Trusting patient-doctor relationship
What surgical presentations can warfarin cause?
Rectus sheath haematoma
Intraperitoneal bleeding
Retroperitoneal haematoma
What are the main causes of acute pancreatitis?
Gallstones
Alcohol
What drugs can cause diarrhoea?
Beta blockers ACE inhibitors Statins Antibiotics Metformin Iron Laxatives Mefenamic acid
What drugs can cause constipation?
Antimuscarinics Opiates Iron Laxatives (chronic) Aluminium-containing antacids Mebeverine Gaviscon
How long before surgery should clopidogrel be stopped?
7 days before
How long before surgery should aspirin be stopped?
DO NOT STOP
Cardio and cerebroprotective benefits outweigh slight increased bleeding risk
How should statins be managed perioperatively?
Don’t stop
Reduce periop mortality
How should beta blockers be manage perioperatively?
Don’t stop
Risk of rebound angina/infarction when stopped suddenly
How should oral hypoglycaemics be managed perioperatively?
Stop from day of surgery
How should the OCP be managed perioperatively?
Stop at least 4 weeks before surgery (give alternative contraceptive advice)
Restart 2 weeks after surgery
How should HRT be managed periop?
Stop at least 4 weeks before surgery
Restart 2 weeks post-op
How should steroid be managed periop?
DO NOT STOP
Can lead to Addisonian crisis
When should warfarin be stopped before surgery?
AF: 5 days
Prosthetic heart valve: 5 days, keep INR 2-3 using heparin
Previous DVT/PE: 5 days, high-dose prophylactic LMWH
How do you immediately reverse warfarin?
Beriplex - synthetic factors 2, 7, 9 and 10
How else can you reverse warfarin?
IV vitamin K (1-5 mg slowly)
Takes 3hrs
How can you check for postoperative ileus?
Ask the patient if they have passed wind
If yes, then the colon is working and hence everything else is too
Which patients should have prophylactic LMWH?
All patients over 20 having abdominal surgery
Patients having neck surgery should not
What dose of dalteparin is used for VTE prophylaxis?
2,500 or 5,000 for high-risk patients
What antibiotics are used for prophylaxis of wound infection?
Ceftriaxone + metronidazole
Or augmentin
What is the treatment for opiate OD?
Naloxone 0.4mg IV
What are the steps involved in reversing anaesthetic?
Wellbeing (pain and PONV) then C B A…
CVS stable
Breathing for themselves
Airway (&O2)
Name a muscle relaxant commonly used in anaesthesia
Atracurium
Why might atropine be given in laparoscopic surgery?
Vagal nerve stimulation can cause bradycardia
Why is increased pressure needed to ventilate patients during laparoscopic surgery?
Abdomen is inflated, making it harder for the diaphragm to move down
How are CO2 levels managed during surgery?
If pCO2 rises during op, increase rate of ventilation
High pCO2 at the end is good as it stimulates the patient to start self-ventilating
What are the potential respiratory complications post-op?
Hypo ventilation
Hypoxia
What can cause hypo ventilation postop?
Upper airway obstruction - decreased muscle tone, secretions, sleep apnoea
Laryngeal obstruction
Opioids causing respiratory depression
What can cause hypoxia postop?
Hypo ventilation
Ventilation perfusion mismatch eg PE
Pain
Using too much O2 eg shivering
Why should patients only be delivered to the ward once they have a normal temperature?
Shivering increases O2 demand
Hypothermia reduces enzyme activity in clotting
Heat needed for wound healing
What can cause postop hypotension?
Drugs
Epidurals
Volume loss
What is the main cause of postop hypertension?
Pain
What are the risk factors for PONV?
Motion sickness Gynae surgery Previous PONV Child Female Anxiety
What are the anaesthetic causes of PONV?
Opioids
Gases
Pain
Not enough fluid
What are the 5 parameters measured in EWS?
Heart rate Resp rate Temperature BP CNS (AVPU)
What is the most important parameter in EWS?
Resp rate. Indicates hypoxia, hypercapnia and metabolic acidosis (DKA, sepsis, lactic acidosis)
How should you give oxygen to a COPD patient?
Venturi mask
What concentration of oxygen do nasal cannulae deliver?
24-35%
Define pain
An unpleasant emotional and sensory experience resulting from a stimulus causing, or likely to cause, tissue damage
What are the effects of pain?
Tachycardia, hypotension
Inability to deep breathe or cough
Nausea and poor appetite
Poor mobility
Stress response - sodium and water retention, oedema
Poor sleep, depression, illness behaviour, inability to work
What is the pain pathway?
Stimulus Dorsal horn of spinal cord Modulation in Rexed laminae Ascending pathways Modulation by brain Descending pathways Effector site reflexes
What does neuropathic pain feel like?
Burning
What is step 1 in the WHO pain ladder?
Non-opioids eg aspirin, NSAIDs or paracetamol
What is step 2 on the WHO pain ladder?
Mild opioids eg codeine, with or without non-opioids
What is step 3 on the WHO pain ladder?
Strong opioids eg morphine, with or without non-opioids
How does paracetamol work?
Inhibits CNS prostaglandin synthesis and blocks bradykinin-sensitive chemoreceptors peripherally
What is the adult dose of paracetamol?
1g every 4-6hrs
How do NSAIDs work?
COX inhibition to reduce synthesis of peripherally-acting inflammatory mediators of pain
What does COX-1 do?
Constitutive production of inflammatory mediators eg GI, renal
What are the side effects of NSAIDs?
GI: peptic ulcers, erosions and GI haemorrhage
Renal: can reduce renal blood flow
Resp: bronchospasm
Bleeding: anti-platelet effect
Cardiac: fluid retention and cardiac failure in borderline patients
What is the relationship between codeine and morphine?
10% of codeine is metabolised to morphine
Side-effect profile may be similar
What is the adult dose of codeine?
30-60mg hourly
Give 3 examples of strong opioids
Morphine
Pethidine
Fentanyl
How does morphine work?
Acts on M and K opioid receptors in brain and spinal cord
Reduce membrane excitability to nociceptive impulses
What are the side effects of morphine?
Respiratory depression Reduced response to hypoxia and hypercapnia Anti-tussive (stops coughing) Nausea, vomiting, constipation Urinary retention Drowsiness
What is the adults dose of morphine?
0.1-0.2 mg/kg
What is PCA?
Patient controlled analgesia
Pump programmed to deliver a bolus dose of drug when the patient operates a hand set
Dose is 1mg with a lock-out of 5 mins
Where is an epidural put?
Epidural space (potential space) Space in which nerves run to join the cord
Where is spinal analgesia inserted?
Into the CSF
Blocks fibres at the cord level
What is entonox?
Gaseous mixture of 50% O2 and 50% nitrous oxide
Why may hospital patients be malnourished?
Increased nutritional requirements Increased losses eg stoma Decreased intake eg dysphagia Treatment effects (nausea, diarrhoea) Enforced starvation Missing meals Difficulty feeding Unappetising food
What is the best form of nutrition?
Enteral - through GI tract
When should parenteral nutrition be considered?
If the patient will become malnourished without it
Eg small bowel Crohn’s when food not being absorbed
How is TPN given?
Central venous line or PICC line
What are the potential complications of TPN?
Sepsis from central line insertion
Thrombosis in central vein may lead to PE
What are the 3 indications for IV fluids?
Maintenance
Resuscitation of pre-existing deficit
Replacement of ongoing losses
What proportion of bodily fluid is extracellular?
1/3
What proportion of body fluid is intravascular?
1/15
What is the minimum urine output that is considered adequate?
0.5ml/kg/hr
Why are even small changes in plasma potassium bad?
Potassium is mainly intracellular
There may be large changes before plasma levels change
Why do IV fluids need to be isotonic with plasma?
If hypotonic - red cell haemolysis
If hypertonic - red cell crenation
Name 3 crystalloid fluids
Normal saline
Dextrose
Hartmann’s
Name 4 colloid solutions
Volpex
Starch
Albumin
Blood products
What does 1 litre of 0.9% normal saline contain?
154mmol Na+
154mmol Cl-
What does 1 litre of Hartmann’s contain?
131mmol Na+
5mmol K+
111mmol Cl-
What is the maximum safe rate to deliver IV potassium?
5mmol/hr
What proportion of 5% dextrose solution remains in plasma?
1/15
Glucose taken up rapidly by cells, so solution acts just like water
What proportion of 0.9% saline remains in plasma?
1/5
What proportion of colloid solutions stays in plasma and why?
All of it
Contains proteins, which can’t cross the capillary membrane. Their osmotic effect means all the water remains in plasma too
What are the maintenance requirements of sodium for adults?
2mmol/kg/24h
What are the maintenance requirements of water for adults?
40ml/kg/24h
What are the potassium requirements for adults?
1 mmol/kg/24h
When may fluid replacement be required?
Vomiting
Diarrhoea
High output stoma
Enterocutaneous fistula
What ions is diarrhoea rich in?
K+ and HCO3-
What ions is vomit rich in?
K+, H+ and Cl-
How do you assess a patient’s fluid status?
Peripheral perfusion Pulse rate, blood pressure JVP Flow-based measurements Urine output
