Generic Periop Flashcards
why is a preop assessment carried out
to assess patient’s medical and physical state before surgery, determining possible complications and seeing what can be done to optimise a patient’s health preop
list the medications specifically asked about in the preop assessment
- heparin
- warfarin
clopidogrel - steroids
- contraceptive pill
- HRT
why can steroids be a problem in surgery
steorids can cause adrenal suppression - as cortisol is usually increased during surgery; suppression may result in decreased BP or circulatory collapse during surgery
list the risk factors for PONV
- female
- motion sickness
- duration of surgery
- diabetes
- laparoscopic surgery
- previous PONV
(each score one point)
list the preop bloods
FBC, INR/clotting, electrophoresis, u + e, LFT, lipids, glucose, HbA1C, TFT, G+S
list some of the preop investigations done in the preop assessment
ecg cxr msu pregnancy mrsa
how is a patient who tests positively for mrsa in preop assessment be treated
the planned op may need to be delayed. treatment includes antibacterial wash, nose cream, side room admittance if urgent surgery
what is APACHE scoring
classification system rating severity of patien’s risk of dying in hospital; takes into account factors such as core temp, HR, BP, creat, age, chronic illness
what are high risk respiratory patients going for operations
asthma, COPD +/- steroid therapy. need to get this optimal
why should diabetes patients be put first on the list for operations
prevent hypo
which cardiac conditions increase operative risk
cvd/hf.arrhythmia/ihd
how may alcoholism affect a patient going for an operation
may be tolerant to BZDs, anaesthetic agents e.g. propofol requiring higher doses
how may obesity affect patients going for operations
may require higher O2 concs, make BP measurement less reliable, iv access more difficult
list some neurological/neuromuscular conditions significant in patients having surgery
malignant hyperthermia, myasthenia gravis, MS, stroke, Parkinson’s, muscular dystrophy, MND, myasthenic syndromes, epilepsy, dementia, Guillain Barre
what should a preop referral letter for a diabetic patient ideally contain
HbA1C, BP, wieght, details of complications, written information if drug regimen changes need to be made
how should insulin therapy during surgery be administeres
in 0.45% NaCl and glucose, with KCl to maintain electrolyte balance,
how are diabetic patients managed perioperatively in terms of drug regimen alterations
- put first on list
- stop long acting insulin night before
- SC insulin omitted in morning if morning surgery; if op in afternoon then give morning insulin with breakfast
how often should you check blood glucose in a patient with diabetes, having surgery
hourly intraop then two hourly post op
how do you manage diabetic patients intraoperatively
set up infusion pump with sliding scale insulin
how do you manage diabetic patients post op
continue IV insulin + dextrose post op until patient can manage to feed
finger prick blood glucose every 2 hours
how do you manage a non insulin-dependent diabetic who is undergoing surgery
- if poorly-controlled treat as per DM1
- do NOT igve long acting sulfonylureas on morning of surgery
- start SC/IV insulin if having major op
- take oral hypoglycamics as normal on preceding day and stop on morning of surgery
what is a PICC line
peripherally-inserted central catheter, which is a form of iv access for a prolonged period of time
what may PICC lines be used for
chemo, extended abx, tpn
list some of the veins that a central line (or central venous catheter) may be inserted into
internal jugular or other veins including subclavian, axillary, femoral
what do central lines give an indication of
right atrial pressure therefore RV preload
what is the dose of cyclizine
50mg
what is the mech of action of cyclizine
anticholinergic/antihistaminic
what is the mech of action of ondansetron
5ht3 receptor antag
what is the mech of action of metoclopramide
D2 anatgonist
what is the dose of metoclopramide
10mg tds
what is the mech of action of prochlorperazine
D2 antagonist
what is the mech of action of hyoscine bromide
anticholinergic
what are the side effects of anticholinergics
drowsiness and xerostomia
what are the side effects of 5ht3 antagonists
confusion, dizziness, tachy
what are the side effects of dopamine atagonists
EPSE, resp depression, dystonia, restlessness, drowsiness
what is delirium (post op s/e)
organically-caused decline from previous cognitive function. has a fluctutating course, clouding of consciousness, behavioural changes, arousal changes, perceptional changes, sleep-wake cycle disturbance
what is dementia
long term gradual decline in cognitive function, with memory disorders, personality change, problems with language/emotional motivation/ (different types and underlying causes)
what does POCD stand for
post operative cognitive dysfunction
what is Post-op cognitive dysfunction
short-term decline in cognitive function (compared to before surgery) lasting a few days-weeks post op. distinct from delirium (does not share all the features).
which post op complications are expected to occur within the first 4 days post op
acute mi, pyrexia due to atelectasis, cva
which post op complications are expected within the first 7 days after surgery
renal impairment/failure
post op urinary retention
which post op complication is expected within days 5-10 post op
delerium tremens
which post op complications are expected within days 7-10 post op
chest infeciton, wound infection, uti, secondary haemorrhage
which post op complicatoins are expected from days 10 onwards from operation
dvt, pe, wound dehisence
how should significant post op blood loss +/- shock be managed, or even a late secondary haemorrhage
surgical exploration to find cause
list some of the resp complications that may occur post op
pulmonary collapse, infection, resp failure, plueral effusion, pneumothorax, ARDS
what is the reason that heart problems may occur post op
diseased heart may find it difficult to respond to increased demand in the post op period, e.g. acute hf, mi, arrhythmias etc may occur
list some of the complications associated with IV administration in an operative setting
bruising, haematoma, phlebitis, venous thrombosis, air embolus, site infection,
(if arterial cannula - rarely artery occlusion)
which arrhythmia is the commonest to occur post op, and may be due to haemodynamic disturbance
af
what are the most common types of shock seen as complications post op
hypovolaemic, cardiogenic, septic
what are the common features of cardiogenic and hypovolaemic shock
decreased bp, increased hr, sweating, vasoconstriction
what are the initial features of septic shock
hyperdynamic circultion, fever, rigors, warm vasodilated periphery, bounding pulse
what are the later features of septic shock
hypotension, peripheral vasoconstriction, oliguria, multisystem failure
list some of the renal post op complications
urnairy retention - overflow incontinence
renal failure
uti
what factors can increase chance of urinary retention occuring as a post op complication
pelvic/groin/perineal op
spinal/epidural anaesthesia
post op pain, anaesthetic drugs
list the three steps of virchows triad
increased coagulability, endothelial damage, stasis
list the risk factors for dvt
- obesity
- age
- prolonged op
- hip/pelvic surgery
- varicose veins
- pregnancy
- malignancy
- previous dvt
what adjustments are made for patients on the cocp having surgery
stop cocp 4 weeks before surgery, with alternative contraceptive cover
which two types of compression are used on the leg for patients undergoing surgery
TED graduated compression stockings, and mechanical calf compression (Intermittent Pneumatic Compression)
how is a dvt treated
SC LMWH and Warfarin. LMWH is stopped once fully anticoagulated, and warfarin is continued for 3-6months. inr maintained at 2-3
is pe’s continue to occur depsite anticoagulation post op etc, what measure can be taken
ivc filters
describe epidural anaesthesia
continuous infusion of anaesthetic + opioid into the epidural space, set to a certain rate.
how long can an epidural catheter remain in place for
up to 5 days
list some of the causes of epidural anaesthesia failure
misplacement, displacement, inadequate analgesia, intolerable side effects
what are some complications of epidural anaesthesia
cephalad spread causing resp distress
permanent neurological damage
describe PCA
programmed pump delivers small predetermined doses of a drug (usually opiate) with a minimum period between doses (lock out)
what is a common setting for pca morphine
1mg, minimum 5 min intervals
what are some of the downsides to pca
patient must understand how it works, and have the required manual dexterity to operate it
what layers are gone through in order to insert an epidural
skin, subcut tissues, supraspinous ligament, interspinous ligament, ligamentum flavum, then enter the epidural space (dura mater on innermost)
why may patients who have had operation be more likely to get renal failure
recued perfusion to kidneys due to hypovolaemia, water depletion etc., s well as exacerbation by nephrotoxic agents, sepsis and hypoxia
list some of the things that can cause airway obstruction periop
obstruction by tongue, foreign bodies, layngeal spasm, laryngeal oedema, bronchospasm/bronchial obstruction
how is airway obstruction managed
recovery position
chin lift jaw thrust, guedel airway, o2, may need to reintubate
what should pao2 be
> 13kpa
what is defined as too low an oxygen kpa
less than 6.7kpa
what are the clinical and xray features of ards
impaired oxygenation, diffuse lung opacification on CXR and reduced lung compliance,
list some of the causes of post op ards
TRALI, pulmonary or systemic sepsis, aspiration of gastric contents
what are some of the clinical features of ards
tachypnoea, increased ventilatory effort, restlessness, confusion,
describe the pathophysiology of ards
thought to be due to inflammatory reaction abd release of cytokines, damaged vasculr endothelium, capillary leakage -> cause interstitial and alveolar oedema
what is the management of ards
a-e, ventilatory support, peep (positive end expiratory pressure), treat underlying cause
what are light’s crteria indicating that an effusion is an exudate
- pleural;serum protein >/ 0.5
- pleural:serum lactate >/ 0.6
- pleural fluid lavtate dehydrogenase >/ 2/3 upper limit for serum LD
what periop factors increase the risk of pulmonary collapse for surgical patients
- inability to breathe deeply (e.g. pain) and cough up secretions
- anaesthetics and surgery
- impaired diaphragmatic movement
- oversedation
- cilia paralysis due to inhaled anaesthetics
how may post op pulmonary collapse be prevented
encourage patient to breathe deeply, cough and mobilise
may need chest physio
o2 by mask for hypoxia
(assisted ventilation + endotracheal intubation may be reuired in some cases)
what may cause pulmonary infection in surgical patients
collapse or aspiration
what is step 1 on the WHO analgesic ladder
non opioids and adjuvants e.g. aspirin, nsaids, paracetamol, selective COX-2 inhibitors
what is step 2 on the WHO analgesic ladder
mild opioids e.g. tramadol, cocodamol, codeine phsophate
what is step 3 on the WHO analgesic ladder
opioid ananlgesics - moprhine, fentanyl, (diamorphine, buprenorphine)
list some inhalational anaesthetics
halothane, nitrous oxide, enflurane, isoflurane, desflurane, sevoflurane
do you need a low or high blood:gas coefficient for rapid induction
low (more stays in blood rather than going back into lungs and being breathed out)
what are the two classes of muscle relaxants
depolarising and non-depolarising
list the main depolarising muscle relaxant used in anaesthesia
suxamethonium/succinylcholine
how does suxamtheonium/succinylcholine work
acts like acetylcholine by binding to AchRs, and causes AP’s. However, it is broken down much more slowly and the following depolarisation lasts for an extended period. there is flaccid paralysis.
why is there initial muscle twitching with suxamethonium administration
when the sux binds to AchR’s it causes initial depol and AP’s, causing some initial twitching until paralysis ensues
list four drugs that are non-depolarising muscle relaxants
atracurium, mivacurium
vecocuronium, pancuronium
how do non-depolarising muscle relaxants work
compete with ACh at the NMJ, preventing depolaritisation
how are muscle relaxants reversed
acetylcholinesterase inhibitors e.g. neostigmine to increase synaptic cleft ACh levels, hence compete with muscle relaxants bound to the receptors
what are some of the adverse effects of IV anaesthetics
irritant to veins/painful, respiratory/cardiovascular depression
which act more rapidly inhalational or iv anaesthetics, and why
iv - as they bypass the paradoxical excitement phase
list some iv anaesthetics
propofol, thiopental, etomidate
others: BZDs e.g. midazolam, diazepam
ketamine for short operations
what is the mechanism of action of propofol
potentiates GABA(A), but also Na channel blocker
list some of the analgesics used in anaesthesia
morphine, pethidine, diamorphine, codeine, tramadol, fentanyl/alfentanyl/remifentanyl, co-codamol
what is the mech of action of pethidine
like morphine - mu opioid receptor agonist
list some local anesthetics
lidocaine, bupivicaine, levobupivicaine
which has the shorter half life, lidocaine or bupivicaine
lidocaine
which of the muscle relaxant classes are longer acting
non-depolarising relaxants - though they have a slower onset of action
list the “premeds” used in anaesthesia
midaz, temaz, and ranitdine to reduce gastric acid secretion
list the drugs used in induction of anaesthesia
propofol, thiopental, etmidate, or inhaled anesthetics
what are the steps in rapid sequence induction of anaesthesia
1) preoxygenate
2) administer anaesthetic induction agent after some analgesia in vein
3) suxamethonium
4) wait for muscle fasciculations to cease
5) laryngoscopy + intubation with endotracheal tube
6) positioning of ET confirmed by presence of end-tidal CO2 trace, bilateral chest movements, auscultation
what are the steps in emergence of anaesthesia
1) administer 100% O2
2) reverse neuromuscular blockade with neostigmine etc
3) extubate only when patient is fully awake and able to remove the ET tube themselves
which agents may be used if bradycardia in emergence form anaesthesia
glycopyrolate or atropine
which part of the brain is triggered to cause N+V
chemoreceptor trigger zone
list the emergency drugs drawn up just in case for patients who go under anaesthesia, and what theyre for
- atropine for bradycardia
- ephedrine for hypotension
- suxamethonium for emergency reintubation
what are the symptoms of a massive pe
chest pain (pleuritic), SOB, pallor, shock
which agents are used for fibrinolysis in patients with a pe
streptokinase or urokinase iv infusion
in severe cases of pe, where fibrinolysis is not enough, what procudure can be carried out to remove the pe
embolectomy
what signs may indicate a wound infection
local erythema, tenderness, cellulitis, swelling, frank abscess, wound discharge, pyrexia, pulse increased
what is wound dehiscence
partial or complete breakdown
what is evisceration
extrusion of abdo viscera through complete abdo dehisence
what is the total body water volume
42L
what proportion of total body water in made up of ecf and icf
ecf - 1/3 (~14L)
icf = 2/3 (~28L)
what proportion of ecf is made up of transcellular fluid, plasma, and interstitial fluid
interstitial + transcellular 4/5
intravasc 1/5 (~3L)
what are the fluid requirements in adults
40ml/kg/24hr
what are the fluid requirements in children
first 10kg = 4ml/kg/hour
next 10kg = 2ml/kg/hour
remainder above 20kg = 1ml/kg/hour
what are the intracellular range for K+ and Na+
K+ = 133 Na+ = 9
what is the extracellular range for K+
3.5-5.5
what is the extracellular range for Na+
143
how is 5% dextrose distributed throughout the body fluid compartments, hence how much remains intravasc
it distributed throughout all body fluid compartments, hence 1/15 remains within the intravasc compartment (1/3 ecf x 1/5 intravasc). hence 1/15 of 1L bag
how is 0.9% saline fluid distributed throughout body fluid compartments
restricted by Na-K-ATPase on cell membrane, hence remains in extracellular compartment thus distributed thoughout ecf only. of the ecf, 1/5 if intravasc, hence 1/5 of 1L (200ml) remains intravasc
how are colloid fluids distributed throughout the body compartments
all remians intravasc (~100%) hence 1L of the 1L bag remains intravasc
how are fluid requirements calculated
maintencnace requirements + preexisting defiict + replace ongoing losses
list some sources of abnormal fluid loss
vomiting, diarrhoea, high output stoma, enterocutaneous fistula
which electrolytes is diarrhoea rich in
K+ and HCO3-
which electrolytes is vomitus rich in
H+, Cl-, K+
which antibodies and which antigens are expressed in group A blood
ag = A ab = B
which antigens and antibodies are expressed in group B blood
ag = B ab = A
which antigens and which antibodies are epxressed in group AB blood
ag = AB ab = - (universal receiver)
which antigens and which antibodies are expressed in group O blood
ag = - (universal donor) ab = AB
how many pints is one unit of blood, hence how many L
1 unit = 1 pint
1 pint ~450mls
how many pints/L of blood are there in the body
pints = ~10 L = 4.7-5.5
define a massive blood transfusion
transfer of 10 Units of blood (whole patient’s circulating volume) in 24hrs
OR >50% of patient’s blood volume (>5 Units) in 4 hours
in response to massive uncontrolled haemorrhage
list the things that are tested for in a patient pre-tranfusion
- blood group
- antibody screen
- x match (compatibility of patient’s blood with donor)
what is the indication for blood transfusion
anaemia secondary to blood loss, Hb
up to what proportion of their circulating blood can a healthy adult lose before feeling any effects
30-40%
list some of the different components of blood that can be transfused into a patient
- red cells
- platelets
- FFP
- cryporeceiptate
- human albumin
- factor VIII/IX
- prothrombin complex concentrate (e.g. Beriplex)
what is FFP used for
multiple factor deficiency e.g severe bleeding or overcoagulation
what does crypoprecipitate contain and what is it used for
fibrinogen, factor VIII, VWF, factor XIII, fibronectin
used when fibrinogen levels are low e.g. DIC
when is human albumin transfusion used
if vascular permeability is increased e.g. burns, oedema, or ascites resistant to treatment with diuretics
when is factor VIII/IX cocentrate used
Christmas disease/ haemophilia
when is prothombin complex concentrate used, and what does it contain
factors II, IX, X, VII (vit K dependent). to reverse the nticoag effects of warfarin when there is major bleeding
what checks are one when transfusing a patient with blood
- correct patient
- completed blood request form
double check identitiy of atient, abo and rhd type compatibility - check donation number on pack, expiry, ensure no leaks/haemolysis
- vital signs before transfusion, during and after
list some acute reactions to blood transfusion
- acute haemolytic transfusion reaction
- TRALI
- febrile non haemolytic transfusion reaction
- allergic reaction
- sepsis due to bacterial contamination
- circulatory overload
why would acute haemolytic transfusion reaction occur
abo incompatibility
why would TRALI occur
Ab’s in donor plasma react with recipient’s leucocytes
why would febrile non-haemolytic transfusion reaction occur
neutrophil Ab in recipient plasma reacts with donor leucocytes
list some delayed transfusion reactions
- delayed haemolytic reaction
- allommunisation
- post transfusion purpura
- graft vs host disease
- transfusion-transmittted infections e.g. bbv, cmv
- iron overload (accumulation in tissues)
what is alloimmunisation in tranfusion of blood
ab are formed in response to donor antigens
why may post transfusion purpura occur
platelet specific antibodies attacking platelets
list three methods of autologous transfusion
- preop donation
- isovolaemic haemodilution
- cell salvage
how does preop donation work as autologous transfusion
patient’s blood is collected prior to surgery and stored for up to 35days preop (usually only used for rare blood groups)
how does isovolaemic haemodilution work
blood drawn preop and put in bag with anticoag + saline, and reinfused during surgery/post op (where significant blood loss is anticipated)
what is cell salvage
blood collected form op site, processed by machine, anticoagulated, cells washed from clots and debris. returned to patient
when is cell salvage contraindicated
malignancy, sepsis
what are the good things and downsides to cell salvage
good = reduced exposure to allogenic blood bad = not haemodyanmically intact due to consumption of clotting factors
list three reasons why direct arterial pressure monitoring may be carried out
- failure of indirect monitoring
- arterial blood sampling
- continuous reactive monitoring
what is a possible complication of direct arterial monitoring
distal ischaemia
list some of the complications of arterial catheter placement
arterial puncture, haematoma, haemothorax, nerve injury, pneumothorax, air embolism, sepsis, endocarditis, venous thrombosis, pe, cardiac tampomade
what is prothrombin time a measure of
for those on warfarin (like inr), extrinsic factors VII, V, X, prothrombin and fibrinogen
what des prolonged prothrombin time indicate
deficiency in one or more of the factors tested for - can mean there is a vit k deficiency, or liver disease
what does aptt measure
used for patients on heparin to measure intrinsic system factors e.g. XII, XI, VII, IX
what does increased aptt mean
deficiency in clotting factors tested for, liver disease, bleeding disorder etc
what is the mechanism of action of warfarin
inhibits vitamin K - dependent synthesis of biologically-active forms of clotting factors II, VII, IX and X, as well as protein C and S. inhibits reduction of vitamin k
what is the mechanism of action of unfractionated heparin
works by binding to antithrombin III, thrombin and factor Xa
what is the mechanism of action of lmwh
binds to ATIII and factor Xa (NOT thrombin)
what is ASA I
normal healthy patient
what is ASA II
patient with mild systemic disease, and no functional limitations
what is ASA III
patient with moderate or severe systemic disease, that results in some functional limitation
what is ASA IV
patient with severe systemic disease that is a constant threat to life and functionally incapacitating
what is ASA V
moribund patient, who is not expected to survive 24 hours without surgery
how many days before surgery must clopidogrel be stopped
7
where does haemopoeisis occur in the first few weeks
yolk sac
where does haemopoeisis occur in the next few months of life
liver and spleen
where does haemopoeisis occur after 6-7months after conception
bone marrow
what are the two main cell lines from whcih blood components arise
common myeloid and common lymphoid
why may extramedullary haemopoeisis occur
failure of bone marrow to produce blood cells
which factor is important in B12 absorption
intrinsic factor
why do red blood cells require folate and vit B12
to progress through mitosis
except for rbc changes, what other blood cellsdoes vit b12 and folate deficiency cause
giant hypersegmented neutrophils
which drug s given to chelate iron in those with sickle cell disease
hydroxycarbamide
what is the difference between alpha and beta thalassaemia
alpha thalassameia is caused by alpha genes missing/inactive wherease beta is caused by beta genes missing/inactive
what do rbc’s look like in vit b12 deficiency
large, oval shaped
which bbvs can cause immune destruction of platelets
hiv, hep
give some common causes of microcytic anaemia
thalassaemia, anaemia of chronic disease, iron deficiency
Which INR level is acceptable for surgery
Less than 2.5
What is sick sinus syndorme
Sinus node dysfunction which causes one of two things
- tachy Brady syndrome
- Brady +/- arrest
How you manage a patient with sick sinus syndrome
Pacing
How may you be able to control ventricular rate in atrial fibrillation/flutter
Digoxin loading dose followed by maintenance
What is an avnrt (AVN ree try tachy)
Ree try circuit within or just next to the AVN
Which arrhythmia is avrt commonly associated with
Wpw syndrome
What is avrt (av reentry tachy)
Accessory pathways occurs between the atria and ventricles allowing electrical signal to pass from ventricles back to atria and cause premature contraction. This occurs alongside the normal AVN pathway, where depolarisation goes down heart normally and back up into atria through accessory pathway - loop. Creates a complete re entrant tachy
What is wpw syndrome
Individuals have an accessory pathway that doesn’t share the rate slowing properties of the AVN (bypasses this) - hence electrical activity is conducted at a higher rate
Retrograde or anterograde
Type of preexcitation syndrome
List the differentials for narrow complex tachycardia
Sinus tachy SVT AF Atrial flutter Junctional tachy
List the differentials for broad complex tachy
Vt, incliding torsades de pointes
SVT with aberrant conduction
What is a capture beat
Normal qrs between abnormal beats
What is a fusion beat
Normal beat fuses with vt complex
List the different types of junctional tachy
- avrt
- avnrt
- his bundle tachy
What drug do you initially give to someone with a junctional tachy
Adenosine
What is carcinoid syndrome
Array of symptoms that occur secondary to carcinoid tumours. Includes flushing, diarrhoea, and less frequently heart failure and bronchoconstriction
Caused by endogenous secretion of serotonin and kallikrein
What is a rock all score used to calculate
Risk of death in a patient with an acute upper gi bleed
List the parameters involved in calculating a rockall score
- age
- shock/haemodynamic instability
- comorbidities e.g. Ihd, liver/kidney disease
- diagnosis, Malory Weiss, upper gi ca, any other
- avoidance of belled ding on ogd
What is the blatchford score
In gi bleeds, used to assess if patients can be managed out of hospital or need to be in a hospital setting