Perioperative Flashcards
Define a fistula
Abnormal tract between two epithelial surfaces
Define a sinus
A blind ended cavity lined with epithelium
Define a hernia
An abnormal protrusion of an organ through the wall of the cavity it is contained in.
Which types of hernia are usually asymptomatic?
Hiatus and umbilical
What are the signs of limb ischaemia? Indicate which are early and which are late signs.
Early - Pale, Parasthesia, Pain, Perishingly cold
(if compartment, passive stretch pain, palpable swelling)
Late - Pulseless, Paralysis
What is the rule of 2s for meckels diverticulum?
2% of population Presents before 2 years 2:1 male:female 2 inches long 2 ft above ileocaecal valve (In small intestine)
What is a meckels diverticulum?
Remnant of the vitelline duct (yolk sac to midgut)
Contains 2 different types of mucosa, can include pancreatic or gastric.
How can a meckels diverticulum cause complications?
- Vitelline fistula (poo at umbilicus soon after birth)
- Haemorrhage - (Gastric mucosa - peptic ulcer)
3 Small bowel obstruction (adhesions, stones, torsion) - Diverticulits
- Intussusception
How do you differentiate between the 3 main causes of acute RUQ pain?
All colicky pain, provoked by fatty meal.
Biliary colic - No fever, no CRP
Acute cholecystitis - +fever, CRP, Murphy’s sign (stop breathing when press RUQ)
Ascending cholangitis - +jaundice
(Charcot’s triad of pain, fever and jaundice is ascending cholangitis)
How do you differentiate between the 3 main causes of acute epigastric pain?
Peptic ulcer - NSAID use, alcohol, reflux
Gastric - worse when eating
Duodenal - relieved by eating
Acute pancreatitis - radiates to back, alcohol, gallstones, fever.
How do you differentiate between the main causes of acute central abdominal pain?
Early appendicitis - pain on palpation RIF, anorexia, tachy, fever
Acute pancreatitis - radiates to back, alcohol, gallstone, fever
IBD flare - diarrhoea/constipation, blood in stool, joint pains, skin signs, mouth ulcers
Obstruction - vomiting (small), complete constipation (large), tinkling bowel sounds. Hx adhesions or Ca.
Ectopic - repro age, amenorrhoea
AAA - elderly man, radiates to back, hypotensive, tachy, IHD
Mesenteric ischaemia - AF/ cardio disease, diarrhoea, metabolic acidosis from the latate produced by necrosis.
How do you differentiate between the main causes of acute RIF pain?
Appendicitis - anorexia, tachy, fever, moved from early central pain
Ectopic - repro age, amenorrhoea
IBD flare - diarrhoea/constipation, blood in stool, joint pains, skin signs, mouth ulcers
How do you differentiate between the main causes of acute LIF pain?
Diverticulitis - elderly, colicky, diarrhoea, fever, CRP, white cells
Ectopic - repro age, amenorrhoea
How do you differentiate between the main causes of supra pubic pain?
UTI - female, dysuria, frequency
Urinary retention - male with history of BPH
Torsion - absent cremasteric reflex
How do you differentiate between the main causes of acute abdo pain radiating to the back?
AAA - elderly man, hypotensive, tachy, IHD
Acute Pancreatitis - alcohol, gallstones, fever.
Pyelonephritis - loin to groin pain, fever, rigors
Renal colic - colicky, severe pain, haematuria
When would it be appropriate to prescribe Hartmann’s fluid?
When replacing isotonic fluid loss.
eg after surgery, diarrhoea and vomiting, blood loss
When would it be appropriate to prescribe a dextrose - saline fluid regimen?
When replacing hypotonic fluid loss
eg dehydration, diabetes insipidus
When is it especially important to avoid pure saline? (ie 0.9% normal saline only)
Post op and in sepsis.
Because cell lysis and leaky capillaries respectively lead to increased electrolytes. Pure saline will lead to Na overload.
How should you treat a fluid overloaded heart or renal failure patient?
Reverse with furosemide
Start fluid chart
Catheterise
What is the universal recipient blood type?
AB+
What is the universal donor blood type?
O-
What is a massive haemorrhage?
100% blood volume (5L) in 24 hours
50% blood volume in 3hrs
or
150ml/min
What are the signs and symptoms of acute haemolysis in reaction to a blood transfusion?
Shock - fever, AKI, respiratory distress, hypotension, tacchycardia, restless.
Chest pain radiating to the back.
What is the pathophysiology of an acute haemolytic reaction to a blood transfusion?
Host antibodies IgG and and IgM respond to the antigen (A or B) on the donor blood cells.
They bind to the donor cells, activate complement and lead to haemolysis.
They can also opsonise the rbcs so that they clump together and are captured by macrophages and the RES system.
Massive lysis of rbcs leads to acute anaemia and shock.
What is FFP? When is it used?
Fresh frozen plasma - contains clotting factors, albumin and immunoglobulin.
Therefore used in patients with hepatic failure before surgery as they can’t produce these things well.
Or a massive haemorrhage in a patient on warfarin/ raised INR.
What is tranexamic acid? When is it used?
Blocks plasminogen to plasmin. Less plasmin means clots last longer.
Within 3hrs of an injury to boost the effectiveness of natural clotting.
What is the name of the score to calculate VTE risk in surgical patients? What does it include?
Caprini score
- Age over 60
- Recent stroke or MI
- Hx VTE
- Thrombocytopenia
- CCF/AF
- Obesity
- Hormonal contraceptive/pregnancy
- Type of surgery - arthroplasty, cancer, longer than 45 mins
- Bed bound for 72 hours post op
If 2 points use thromboprophylaxis.
What is the name of the score to calculate PE risk? What does it include?
Well’s score
- Clinical DVT
- PE is number 1 diagnosis or equally likely
- 5 HR >100
- 5 Surgery within 4 weeks or immobile 3 days
- 5 Previous DVT or PE
- Haemoptysis
- Malignancy
If greater than 4 PE likely
What is the sensitivity and specificity of the d dimer? What does this mean?
High sensitivity but low specificity.
Means it can be used to rule out VTE but not a diagnostic tool.
Positive predictive value low
Negative predictive value high
What does the d dimer measure?
Breakdown product of fibronlysis.
Direct measure of plasmin mediated fibrinolysis
What pathological conditions can cause a raised d dimer?
VTE
Acute coronary syndrome
Stroke
Aortic dissection
AF
DIC Sickle cell Infection Superficial thrombophlebitis GI haemorrhage
Malignancy
Pre-eclampsia
Trauma
What non pathological conditions can cause a raised d dimer?
Age Smoking Post-operatively Pregnancy Race (e.g. African Americans)
What is the mechanism of action of warfarin?
Inhibits vitamin k reuctase therefore producing ineffective clotting factors (2,7,9 and 10)
What are all of the options when reversing warfarin?
Prothrombin complex FFP Vitamin k oral Vitamin k IV Stop warfarin
How would you reverse warfarin in an active bleed?
Prothrombin complex (specific clotting factors 2,7,9 and 10) Give with vitamin k due to short half life.
Add FFP if ineffective (less specific blood product full of clotting factors, albumin and immunoglobulin)
How would you reverse warfarin for an operation within 24 hours?
Oral vitamin k
How would you reverse warfarin for an operation within 6-8 hours?
IV vitamin k
How would you reverse warfarin for an elective operation?
Stop warfarin 5-7 days before
Operation goes ahead when INR is below 1.5
Consider heparin bridging
What is the advantage of LMWH over normal heparin?
Low risk of HIT (heparin induced thrombocytopenia) longer half life, no APTT monitoring.
(Normal heparin required in renal failure)
What is the thromboprophylactic dose of LMWH for a 70kg man? When should it be started around surgery?
Dalteparin - 2500 units SC BD
Enoxaparin - 40mg SC OD
6-12 hours post operative
When should a woman stop taking the COC before surgery?
4 weeks before
When should clopidogrel be stopped before surgery?
7-10 days
Unless prosthetic valve, in which case continue dual antiplatelet with aspirin
When should aspirin be stopped before surgery?
On the day
Unless prosthetic valve, in which case continue dual antiplatelet with clopidogrel/prasugrel/ticagrelor
How should hypoglycaemics be adapted before surgery in a well controlled diabetic on oral medication?
Sulphonylureas - stop on the morning (risk of hypo)
Continue metformin and pioglitazone
Monitor BM throughout periop period and place first on the list
How should hypoglycaemics be adapted before surgery in an insulin dependent diabetic?
Sliding scale throughout peri op period (risk of hypo)
Which antibiotics should be used for surgical prophylaxis?
IV Gentamicin and metronidazole
1 hr prior to surgery
Which surgical procedures require prophylactic antibiotics?
Anything except clean surgery eg. GI - eg appendix Caesarean Cataract MSK
Which surgical procedures do not require prophylactic antibiotics?
Inguinal hernia repair
Lap chole
Tonsillectomy
What are the risk factors for post operative nausea and vomiting?
Female
Gynae and ENT
Hx N and V
General anaesthetic
What are the types of anti emetic?
H1 antagonists - cyclizine
5HT antagonists - ondansetron
Dopamine antagonists (prokinetic) - domperidone, metoclopramide
What is the mechanism of action of cyclizine?
H1 antagonist. (antihistamine)
Blocks action of histamine from brain and middle ear on the vomiting centre in the medulla.
What is the mechanism of action of ondansetron?
5HT antagonist.
Blocks lots of actions on vomiting centre in the medulla.
From brain and middle ear, from the chemoreceptor trigger zone in the area postrema in the floor of 4th ventricle and from GI tract.
What is the mechanism of action of pro kinetic antiemetics? Can you give 2 examples?
Dopamine antagonists.
Domperidone and metoclopramide.
Block action on vomiting centre in the medulla from the chemoreceptor trigger zone in the area postrema in floor of the 4th ventricle and the GI tract.
What is the mechanism of loperamide?
Opioid agonist that doesnt cross the bbb
What is the major side effect of loperamide?
Risk of toxic megacolon in IBD
What are the types of laxative?
Bulk - Fybogel (methylcellulose + ispaghula husk)
Stimulant - senna
Osmotic - lactulose, movicol, phosphate enema
Stool softener - arachis oil
What is the mechanism of action of fybogel (methyl cellulose + ispaghula husk)?
Bulk forming by undigested hydrophillic substance that increases volume of stool.
Can help in both constipation (by increasing peristalsis and softening stool) and diarrhoea (by solidifying stool)
Therefore very good in IBS where there may be both symptoms
What is the mechanism of action of senna?
Stimulates intestinal muosa to produce water.
What is the mechanism of action of lactulose?
Osmotic agent.
Undigestible starch that draws water into the lumen by osmosis
What should be prescribed as an initial fluid challenge for a maintenance regime?
500ml 0.9% saline at 30ml/kg/24hr
Therefore for a 75kg man needs 500ml at a rate of 100ml per hour
What should be prescribed as a fluid challenge in a replacement regime?
500ml 0.9% saline stat
Describe the ASA classes of risk for anaesthesia.
ASA I No systemic disease
ASA II A patient with mild systemic disease
ASA III A patient with severe systemic disease
ASA IV A patient with severe systemic disease that is a constant threat to life
ASA V A moribund patient who is not expected to survive without the operation
What is the electrolyte disturbance seen in an addissonian crisis?
With vomiting, Low sodium high potassium think addissonian
What reverses heparin? When is it routinely administered?
Protamine sulphate.
When coming off cardiac bypass because lots of heparin has been used.
What imaging is required before a patient with rheumatoid arthritis has a general anaesthetic?
AP and lateral C spine x rays to check for atlantoaxial subluxation.
What are the most common post op complications in timeline order?
1- 4 days atelectasis + or - pyrexia stroke MI paralytic ileus addissonian crisis
1-7 days
Urinary retention
AKI
5-10 days
delirium
7-10 days
Infection - chest, wound, UTI
Secondary haemorrhage
10-14 days
VTE
Wound dehiscience
Which groups of patients require a pre op ecg?
Over 65
Renal disease
Diabetes
Cardiovascular disease
What routine bloods are required pre op?
Fbc - for baseline for infection/anaemia
U and e’s - for baseline in case of AKI
Crossmatch and clotting in case of bleed
For a patient on steroids, what should happen to their medication over surgery? Why?
Steroid cover
Hydrocortisone IV at induction then normal dose 8 hourly for 72 hours.
Otherwise risk of addissonian crisis.
What is the appropriate crossmatching for the following types of surgery?
Appendicectomy Total hip replacement AAA repair Cystectomy Lap Chole
Appendicectomy - group and save Total hip replacement - x match 2 AAA repair - x match 4-6 Cystectomy - x match 4-6 Lap Chole - group and save
Unlikely bleed - group and save
Likely bleed - x match 2
Definite bleed - x match 4-6