Peri-op care and prep before investigations Flashcards
complications of bowel preparation in colorectal surgery?
dehydration
perforation
liquefying bowel contents which are spilled during surgery
electrolyte loss, leading to seizures and hyponatraemia
higher rate of post-op anastamotic leakage
importance of nutrition?
wound healing
reduced infections
faster recovery
reduced loss of muscle mass
daily calorie requirement?
30kcal/Kg/day
types of enteral feeding?
supplements nasogastric tube nasojejunal tube percutaneous endoscopic gastrostomy jejunostomy
complications of enteral feeding?
aspiration
re-feeding syndrome
complications of total parenteral nutrition?
line thrombosis
sepsis
metabolic imbalance, fluid o.load, electrolyte imbalance, liver damage
mechanical e.g. pneumothorax, e.g. with SC line
describe re-feeding syndrome
Occurs in the severely malnourished Hypophosphatemia Cellular dysfunction Cardiac arrhythmia Prevent by close attention to K, PO, Mg
3 components to consider in hypotensive ptnt post op?
reduction in circulating volume (preload)
reduction in CO- reduced myocardial contractility, arrhythmias, valvular dysfunction
vasodilatation (afterload)
most common cause of hypotension after surgery?
hypovolaemia e.g. bleeding in surgery, continued bleeding, tissue damage causing oedema, or evaporation during prolonged surgery on body cavities e.g. abdomen and thorax.
how is hypovolaemia post op diagnosed?
reduced peripheral perfusion- CRT >2s, cold clammy skin, in absence of fear, pain and hypothermia
tachycardia- PR>100bpm of poor volume
hypotension, and narrow pulse pressure- DBP elevated due to compensatory vasoconstriction
inadequate urine output- <0.5ml/kg/h, should be measured hrly with catheter.
causes of a reduced urine output post op, other than hypovolaemia?
blocked catheter
hypotension
hypoxia
renal damage intraoperatively e.g. in AAA surgery or hysterectomy
most common causes of oliguria and anuria?
oliguria- hypovolaemia
anuria- blocked catheter
in which ptns might hypovolaemia post op not be detected?
young, fit ptnt who can lose up to 15% of blood volume without detectable signs
ptnt on beta blockers may not be seen as having tachycardia
management of hypovolaemia post op?
ensure adequate oxygenation and ventilation
give IV fluid
X match blood
stop any external haemorrhage with direct pressure
monitor CVP if cardiac function is in question
arterial blood sample- lactic acidosis?
why might a ptnt have adequate oxygen sat.s despite inadequate ventilation?
receiving O2 therapy
features indicating L ventricular dysfunction post op?
tachypnoea tachycardia poor peripheral circulation- cold clammy hands, CRT>2s distended neck veins, raised JVP basal crepitations on lung auscultation wheeze with productive cough triple rhythm on heart auscultation
management of L ventricular dysfunction post op?
sit ptnt upright give 100% O2 monitor ECG, BP, and SpO2 can give fluid challenge if diganosis unclear, an improvement in circulatory status suggest hypovolaemia if sure of diagnosis, can give a diuretic and restrict fluids initially monitor CVP trends care in critical care area use of inotropes and vasodilators
most common arrhythmia after anaesthesia and surgery?
sinus tachycardia (>100bpm)
usually result of pain or hypovolaemia
if assoc with pyrexia, may be early indication of sepsis
what might development of an unexplained tachycardia post anaesthesia rarely be the 1st sign of?
malignant hyperthermia/hyperpyrexia
tment of sinus tachycardia post-op?
give O2
analgesia
adequate fluid replacement
possible beta blocker if persists
causes of sinus bradycardia post op?
inadequate dose of anticholinergic given with neostigmine to reverse NMB
excessive suction to clear pharyngeal or tracheal secretions
traction on viscera in surgery
excessive high spread of epidural or spinal anaesthesia
development of acute inferior MI
excessive beta-blockage preop or intraop
medication used intraoperatively to reverse epidural or spinal aneasthesia induced hypotension?
ephedrine hydrochloride
most common supraventricular tachycardia post op?
AF
usually due to IHD or presence of sepsis
if ptnt has sinus bradycardia post op, and low BP, what medication should be given?
atropine, 0.5mg IV
consider adrenaline infusion if no response
O2 should also be given
how is hypotesion secondary to regional aneasthesia corrected?
give fluids
use of vasopressors e.g. ephedrine
or combination of both
give O2
minimum criteria for discharge from recovery area?
fully conscious and able to maintain own airway
adequate breathing
stable CVS, with minimal bleeding from surgical site
adequate pain relief
warm
presentation of post op confusion?
agitation
disorientation
attempts to leave hosp, esec. at night
how to treat post op confusion?
gently reassure patient
may need sedation to examine them- midazolam, or haloepridol
reassure relatives that it is common, and reversible
tests in hypoxic/dyspnoeic ptnt post op?
FBC- pneumonia ?rasied WCC
ABG
CXR- fluid overload
ECG- MI, PE- R axis deviation, RBBB
sit up ptnt and give O2
pulse oximetry
most common form of infection post op?
wound infection
types of infections post op?
wound infection peritonism chest infection UTI cannula site eryhtema menigism endocarditis
common causative organisms of post op wound infections?
staph aureus pseudomonas aeruginosa E coli staph epidermidis enterococcus faecolis
tment of anuria post op?
most likely due to blocked catheter, so flush or replace catheter
tment of oliguria post op?
increase fluid input
how is urine output monitored and managed post op?
review fluid chart and examine for signs of volume depletion= fast pulse rate, cold and pale extremities, CRT>2s, low BP
examine for palpable bladder- urinary retention common
establish normovolaemia- may use CVP line, may need 1L/h IVI for 2-3hr, a colloid bolus over 30 min may also help
catheterise bladder for accurate monitoring, checks Us and Es
refer to nephrologist early if IRF suspected
why is metoclopramide NOT used to treat PONV?
due to its prokinetic property
recent concern over anti-muscarinic drugs e.g. atropine?
dementia
effect of aspirin on risk of GI bleeding?
75mg aspirin daily increases risk of GI bleeding 2-fold
surgical presentations in ptnts on COCP?
DVT/PE mesenteric venous thrombosis ischaemic colitis hepatic adenomas progesterone only increases risk of pregnancy being ectopic
drug causes of pancreatitis?
Alcohol Azathioprine Aminosalicylates ACE inhibitors Frusemide/thiazides L-aspariganase Metroniadazole 6-mecaptopurine Oestrogens Steroids Sulphonamides Tamoxifen Tetracyclines Valproic acid
drug causes of diarrhoea?
ß-blockers Misoprostol Antibiotics Iron Metformin ACE-inhibitors Statins Olsalazine Mefenamic acid Laxatives (acute)
drug causes of constipation?
opioids chronic laxative use antimuscarinics mebeverine gaviscon iron
how is risk of small bowel enteropathy affected by NSAID use?
Small bowel enteropathy (hypoalbuminaemia and iron deficiency) risk is increased 7-fold in NSAI users
drug causes of colitis?
Antibiotics Mefenamic acid Other NSAIs may cause relapse of ulcerative colitis Methyldopa Gold (oral) Penicillamine
is aspirin stopped before surgery?
no
cardio and cerebroprotrective effects outweigh risk of bleeding
are statins stopped before surgery?
no
reduce perioperative mortality
why are beta blockers not stopped before surgery?
if IHD, sudden cessation can cause rebound angina/infarction
risk if oral hypoglycaemics given on day of surgery?
intraoperative hyoglycaemia
when should oral contracetive pills be stopped before surgery and why?
at least 4wks before as 5X increased risk of DVT
restart 2 wks post op
same for HRT,, increases risk by 1.5X
tment of addisonian crisis if sudden cessation of steroids?
?100mg hydrocortisone every 6 to 8 hrs
why is ptnt on warfarin?
AF
previous DVT/PE
prosthetic heart valve
are herbal medicines stopped before surgery?
yes, 2 wks before
as may affect platelet function
problem with metformin and use of iodine containing contrast media?
risk of renal failure
so STOP METFORMIN ON DAY OF PROCEDURE, CHECK U&E’s AT 48-72 hrs AND DECIDE WHETHER SAFE TO RESTART METFORMIN.
recovery times of GI tract post surgery?
small bowel= 0-24 hrs
stomach= 24-48 hrs
colon= 48-72 hrs
in emergency surgery, why is a bolus of Vit K not used to reverse warfarin if ptnt can wait at least 3hrs before surgery?
causes cardiac arrest
so give 1-5mg SLOWLY IV over 30 mins
ptnts having what type of surgery should not receive LMWH prophylactically?
neck surgery
if continuing opioid for more than 3 days post op, what must also be prescribed?
laxative e.g. senna
prochlorperazine (stemetil) can be prescribed for nausea and vomiting. what problem can this cause and how is it reversed?
acute dystonia
treat with procyclidine, an anti-muscarinic, 5mg IV
caution in prescribing NSAIDs post op?
ptnts with renal impairment
define pain
an unpleasent sensory and emotional experience resulting from a stimulus causing tissue damage or likely to cause tissue damage, or expressed in terms of that damage.
effects of pain on body?
tachycardia hypertension inability to deep breathe or cough nausea poor appetite poor mobility stress response- Na+ and water retention, oedema inability to work, depression, insomnia, illness behaviour
caution with use of tramadol in elderly?
can cause confusion
paracetamol dosage?
adults 20mg/kg, typically 1g 4-6hrly, and children=15mg/kg 4 hrly, PO, PR or IV
dose of diclofenac, commonly prescribed NSAID?
100 mg pr 16hrly in adults, 50mg po 8 hrly
example of a selective COX-2 inhibitor?
celecoxib
dose of codeine prescribed?
0.5-1mg/kg
30-60mg 6hrly in adults
active metabolite of morphine that accumulates in renal failure?
morphine-6-glucuronide
initial dose of morphine?
0.1-0.2mg/kg
which places do the LA and opioid act when an epidural is given?
LA on nerve roots
opioid on SC
what score is a measure of hypoxia?
the SpO2, measured via pulse oximetry
what score provides a measure of how much O2 is able to cross the alveolar membrane?
PaO2 measured via ABG, =dissolved O2 in blood
characteristics of O2 given via venturi mask?
fixed O2 concentration
often used in COPD ptnts
drug that can be used post op to treat hypertension?
labetalol- mixed alpha beta adrenergic antagonist
problem with Ryles (nasogastric) tubes if left in nose for >7-10 days?
can cause pressure sores around nose
why does electrolyte imbalance occur with parenteral nutrition?
bypassing liver so lose liver’s protective function against toxicity
how do opioids increase risk of post op chest infection?
reduce cough reflex
min time for IV Vit K to work?
6hrs
why might elderly ptnts be more suitable to use of fentanyl or oxycodone to mangage post op pain rather than morphine?
prinicpal metabolite of morphine= morphine-6-glucuronide has potent opioid effects, and may accumulate in ptnts with renal failure, causing toxicity.
fentanyl and oxycodone have less active metabolites and a faster onset of action.
why might elderly ptnts be more suitable to use of fentanyl or oxycodone to mangage post op pain rather than morphine?
prinicpal metabolite of morphine= morphine-6-glucuronide has potent opioid effects, and may accumulate in ptnts with renal failure, causing toxicity.
fentanyl and oxycodone have less active metabolites and a faster onset of action.
entonox is a weak analgesic with sedative properties, what does it contain and when should it NOT be used?
50% NO and 50% O2
avoided if pneumothorax as NO may diffuse into gas-filled space, increasing the volume.
entonox is a weak analgesic with sedative properties, what does it contain and when should it NOT be used?
50% NO and 50% O2
avoided if pneumothorax as NO may diffuse into gas-filled space, increasing the volume.
what must be considered pre-op in ptnts with regular opioid use?
any current opioid med should be continued on admission to prevent withdrawal
much larger doses of opioid than normal may be required
explain that toxicity from high opioid dose is very unlikely
reassure that addiction is not a concern
what must be considered pre-op in ptnts with regular opioid use?
any current opioid med should be continued on admission to prevent withdrawal
much larger doses of opioid than normal may be required
explain that toxicity from high opioid dose is very unlikely
reassure that addiction is not a concern.
difference between oramorph and zomorh?
oramorph= immediate release, usually used for acute pain where opioid requirement unknown or changing rapidly zomorph= modified release over 12 or 24hr,, useful if opioid tment prolonged and for gradually weaning down dose at end of tment
