Anaesthetics/peri-operative care Flashcards
Define anaesthesia
An-aesthesis- loss of sensation
What is the anaesthetics triad?
Analgesia (comfortable)
Hypnosis (asleep)
Muscle relaxation (immobile)
What is the purpose of GA?
Reversible loss of consciousness
What is the purpose of regional anaesthesia and types?
Numbs an area of the body
- local infiltration
-nerve/plexus blocks
- central neuraxial blocks
Explain triad - asleep
Propofol - IV induction agents causing sleep in arm-brain circulating time
Sevoflurane - volatile agents are dispensed using vapourisers
Explain triad - immobile
Atracurium
Rocuronium
Suxamethonium
…muscle relaxants
Explain triad - comfortable
Opiates, local anaesthesia
What are the phases of GA?
Induction
Maintenance
Emergence
Recovery
What are the minimum monitoring standards?
Capnography
Pulse oximetry
ECG
BP
Agent analyser
Temperature
What are the types of induction agents?
IV Propofol
Thipentone sodium
Ketamine
Volatile agents - sevoflurane
What are two types of muscle relaxants?
Depolarising muscle relaxants - succinylcholine
Non depolarising muscle relaxants - atracurium, rocuronium
What are the two types of intubation?
Endotracheal intubation - emergencies, with ‘full stomach’, long duration surgery
Larngeal mask airways/i gel - elective, well fasted, short duration surgery
Describe maintenance
IV and inhalation
Fluid management
Other essential drugs - abx, insulin
Drugs ro prevent post op n+v
Describe waking up
Wears off - suxamethonium, mivacurium
Withdraw - TIVA, volatiles
Reverse - antagonising non depolarising muscle relaxants - neostigmine + glycopyrrolate
Antagonise - opiates, BZDs (Naloxone)
Stimulate - not often used, doxapram speeds awakening
Describe recovery
Monitoring - EWS, fluid balance
Airway
Side effects of GA - sedation, PONV, shivering
Side effects of regional anaesthesia - monitoring sensory snd motor block levels and hypotension
Observing for complications - bleeding, vascular supply
Post op pain management
Fit for ward tests
Describe follow up
In clinic
Define sepsis
Life threatening organ dysfunction due to dysregulated host response to infection
How is sepsis screened?
qSOFA:
RR>22
Altered mental status
Systolic BP < 100 mmHg
OR
SOFA
What are the red flags for sepsis?
Responds only to voice/pain
Acute confusional state
Systolic BP less than 90 (or drop more than 40 from normal)
Heart rate more than 130
Resp rate more than 25
Needs oxygen for Sp02 more than 90%
Non blanching rash, motttled, ashen, cryanotic
Not passed urine in last 18 hours or output less than 0.5ml/kg/hr
Lactate more than 2mmol/l
Recent chemo
Define septic shock
Sepsis + persistent hypotension or lactate more than 2 after appropriate fluid resuscitation
What is sepsis 6?
Give 02 (so more fhan 94%)
Blood culture
Give iv antibiotics
Give fluid
Measure lactate
Measure urine output
How do you manage sepsis?
Sepsis 6
Identify source
Vasopressors - adrenaline
Organ support
How are deteriorating patients identified?
NEWS
Why is nutrition of surgical candidates important and how is it measured?
Surgery causes physiological stress - hyper metabolic state and catabolic state
Underlying disease reduces their nutritional reserves
Malnourished patients increased risk of post op complications - reduced wound healing, increased infection and skin breakdown
…MUST tool and then expert input from registered dietitian (BMI)
What is the hierarchy of feeding?
If unable to eat sufficient calories - oral nutritional supplements
If unable to take sufficient calories orally or dysfunctional swallow - NGT
If oesophagus blocked/dysfunctions - Gastrostomy feeding
If stomach inaccessible or outflow obstruction - jejunal feeding
If jerjunum inaccesinle or intestinal failure - parenteral nutrition
What are some things to consider in terms of the timing of parenteral nutrition?
SNAP
Sepsis - must be corrected first
Nutrition - after infection corrected give nutritional support
Anatomy - of patients GI tract ro plan surgery
Procedure - once ready
What does a low serum albumen reflect?
Chronic inflammation, protein losing enteropathy, Proteinuria, hepatic dysfunction…not reflect malnutrition
How is intra operative nutrition managed?
Reduction in ‘Nil By Mouth’ times (clear fluids up to 2 hours pre-surgery)
Pre-operative carbohydrate loading
Minimally invasive surgery
Minimising the use of drains and nasogastric tubes
Rapid reintroduction of feeding post-operatively
Early mobilisation
When do you begin enteral diet post surgery?
Within 24 hours
How do you manage nutrition in special circumstances?
Entero-cutaneous fistula - The modern nutritional management of ECF is dependent upon the level of the fistula*. High fistula (jejunal) may need support with enteral or parenteral nutrition, whilst low fistulae (ileum/colon) can be treated with low fibre diet. Thus imaging is often critical to deciding how the fistula should be managed effectively.
High output stoma - depends on length of bowel to stoma
How do you take a history of pre operative assessment?
Why and what procedure, which side
Any abnormal anatomy
CVS disease - hypertension and exercise tolerance, any syncopal episodes or Orthopnea, chest pain
Respiratory disease - oxygenation and ventilation - cough and any obstructive sleep apnoea
Renal disease - baseline function
Endocrine disease - DM and thyroid function
GORD - possible aspiration of gastric contents
Pregnancy
Sickle cell
Past surgical history - any problems
Past anaesthetic history - what, type, any post op N+V
Drug history and drug and non drug allergies
Family hsuorry - malignant hyperthermia
Social history - smoking, alcohol, recreational drug use, language spoken, living situation
Which examinations are required for a pre op assessment?
General - CV, resp and abdo
Airway - mallampati score
…given an ASA grade (1-5) -> morality risk increases
Which blood test are require for pre op assessment?
FBC - anaemia, thrombocytopenia
U and E - renal function for fluid management and analgesia (morphine not in CKD)
LFT - mediation choice
Conditions specific - HbA1C or thyroid function
Clotting screen - iatrogenic, inherited or liver impairment
Group and save - blood group +/- cross match - mixes patients and donors blood - if blood loss expected
Which investigations are required for pre operative assessment?
ECG
Echo
…any ischaemia
Spirometry
Plain chest x day
Urinalysis - UTI
MRSA swab
Cardiopulmonary exercise testing - whether need higher level care
why are fluids prescribed?
resuscitation
maintenance
replacement
how is fluid divided in the body?
around 2/3 of body weight is water…2/3 of this distributes into intracellular fluid and 1/3 extracellular.
1/5 of the extra is intravascular and 4/5 interstitium
how does fluid management differ in a septic patient?
vascular permeability increases…increased hydrostatic pressure and reduced oncotic…fluid enters interstitium…so more fluid required to maintain intravascular volume
how much fluid is balanced from equal input and output?
2.5L (1.5L from urine…others from respiration, sweating and faeces)
how does a patient return clinically imrpove in terms of fluid balance?
vascular permeability returns to baseline state … urinate excess fluid required to maintain intravascular volume
what clinical features indicate a fluid depleted patient?
dry mucous membranes and reduced skin turgor
decreased urine output
orthostatic hypotension
increased CRT
tachycardic
hypotensive
U AND E
what clinical features indicate a fluid overloaded patient?
raised JVP, peripheral or sacral oedema, pulmonary oedema. U AND E
what clinical features indicate a fluid overloaded patient?
raised JVP, peripheral or sacral oedema, pulmonary oedema. U AND E
which electrolytes need balanced?
water, glucose, sodium and potassium
what are the two types of IV fluids?
cystalloids - more widely used, in acute settings and theatres (saline, dextrose, hartmanns)
colloids - high colloid osmotic pressure (but don’t seem to raise intravascular volume faster..) (volplex or gelofusine)
how are fluids mantained?
70kg male:
over 24 hours, 70kg x 25ml/kg/day = 1750 ml of water
70kg x 1mmol/kg/day = 70mmol of K
70 x 1 = 70mmol of Na
50g a day of glucose
1st bag:
500mL of 0.9% saline with 20mmol/L K+ to be run over 8 hours….all Na, around 1/3 of K+ and quarter of water
2nd bag:
1L of 5% dextrose with 20mmol/L K+ over 8 hours…now have 2/3 of K, another half water and glucose
3rd bag:
500mL of 5% dextrose with 20mmol/L k over 8 hours…last 1/3 of K and last 1/4 of water and last 1/4 of glucose
how do you correct a fluid deficit?
if mildly dehydrated…based on clinical estimate and not calculated
if urine output less than 0.5ml/kg/hr…give fluid challenge (250 or 500ml over 15-30 minutes (if 120 kg man may need more than 500ml, but if frail and elderly may need 250)
what other things do you need to consider in regard to fluid loss?
vomit
diarrhoea
fluid losses…bowel lumen in bowel obstruction or retroperitoneum in pancreatitis
what does rhesus D mean?
the presence of absence of rhesus D antigens on red blood cells…mostly rhesus postitve
a rhesus negative patient will make a rhesus D antibody if they are given rhesus positive blood…does not matter as can not attack own red blood cells if not have Rh on them
in pregnancy - if baby is rh pos, she develops anitbodies
and has second child who is rh pos, the anti D antibodies will cross the placenta during pregnancy and bind to foetus RhD antigens …destroys its own red blood cells…haemolytic disease of the newborn
which blood group is the universal donor, and which is the universal acceptor?
donor = 0 neg, can be give to anyone even rh
acceptor = AB pos, give this recipient any time of donor blood
give 2 examples of groups requiring irradiated blood groups
patients with hodgkin’s lymphoma
those recieving blood from first or second degree family members
give 2 examples of when packed red blood cells are required
acute blood loss
chronic anaemia
give 3 examples of when platelets may be required
haemorrhagic shock in trauma patient
profound thrombocytopenia
pre op level low
give 2 examples of when fresh frozen plasma may be required
DIC
any haemorrhage secondary to liver disease
massive haemorrhage
give 3 examples of when cryoprecipitate may be required
DIC with low fibrinogen
vwe disease
massive haemorrhage
what should all operative patients be informed of in advance?
stop eating 6 hours before
stop dairy products 6 hours before
stop clear fluids 2 hours before
drugs to stop - CHOW - clopidogre(7 days), hypoglycaemic agents (subcut to IV insulin), COCP/HRT (4 weeks), warfarin (5 days, INR <1.5, if high given PO vit K). steroids become IV due to risk of addisonian crisis
which drugs need to be started for surgery?
LMWH (UP TO 28 DAYS AFTER)
TED stocking excepet in peripheral vascular disease
antibiotic prophylaxis
explain dextrose
5% dextrose solution
across all body compartments
only 7% of fluid stays in intravascular space…has no role in fluid resuscitation
but maintains hydration and can be given alongside K
explain normal saline
0.9% NaCl solution
into intravascular(25%) and intersitial space …fluid resuscitiation and maintenance
can resulting hypercholraemic acidosis can not be used alone…can also add K
explain hartmann’s
contains Na, K, Cl,HCO3 as lactate, Ca and water
into intra vascular and intersititial spaces
most similar to plasma
wht are some complications of blood transfusions?
clotting abnormalities
electrolyte abnormalities -
hypocalcaemia-chelation of calcium by calcium binding agent, hyperkalaemia- partial haemolysis of rbc’s
hypothermia - blood products are thawed from frozen
acute haemolytic reactions
transfusion associated circulatory overload
transfusion related acute lung injury
mild allergic reactions
non haemolytic febrile reactions
anaphylaxis
infective shcok
what are the clinical features of an acute haemolytic reaction?
urticaria, hypotension, fever,
positive direct antiglobulin test
what are some delayed tranfusion complications?
infection - hepatitis, HIV, syphilis, malaria
graft v host disease
iron overload
what are the 7 most likely sources of infecgtion for spesis?
chest infection
cut
catheter - uti
collections - abdomen
calves - DVT
cannula
central line
define sespsi shock
sepsis with hypotension, despite adequate fluid resuscitation or requiring use of inotropic agents to maintain normal systolic pressure
what are the three types of post op haemorrahge?
primary bleeding - within intra op
reactive - within 24 hours of operation (from a ligature that slips or a missed vessel)
secondary - 7-10 days post op (due to erosion of vessel from a spreading infection)
what are the clinical features of post op haemorrhage and how is it assessed?
tachycardic, dizzy, agitation, visible bleeding, decreased urine output, raised resp rate, airway obstruction (as pre tracheal fascia will only extend so far)
class 1 - 4
how is intra op haemorrhage managed?
urgent fluid rescusitiation
what are the three main types of delirium?
hypoactive delirium - lethargy, reduced motor activity
hyperactive - agitation, increased motor activity
mixed agitation - flutuations
what is the difference between delirium and dementia?
acute, fluctuating, poor attention, common delusions - delirium
insidious, constant, good attention, less common delusions - dementia
what are the risk factors for delirium?
over 65
multiple co morbidities
underlying dementia
renal impairment
male
sensory impairment
what are the common causes of delirium?
hypoxia
infection
drug induced - benzodiazepines, diuretics, opiods, steroids
drug withdrawal - alcohol
dehydration
pain
constipation or urinary retention
electrolyte imbalance
how can you assess delirium?
an abbreviated mental state
mini mental state exam
confusional assessment method
what is the 1st line sedative that can be used in delirium?
haloperidol
what are two medical complications of post op n+v?
aspirational pneumonia and metabolic alkalosis
which patient factors increases the risk of post op n+v?
female
young
previous PONV
opiod analgesia
non smoker
which surgical factors increases the risk of post op n+v?
intra abdominal laproscopic surgery
IC or middle ear surgery
squint surgery
gynaecological surgery
prolonged op time
poor pain control
which anaesthetic factors increases the risk of post op n+v?
opiate or spinal analgesia
inhalation agents
prolonged anaesthetic time
intraop dehydration or bleeding
overuse of bag and mask ventilation
how does vomit and nausea work?
the vomiting centre recieves input from the chemoreceptor trigger zone, GI tract, vestibular ystsem and higher cortical structures (sight, smell, pain)
if the stimuli are sufficient, it acts on the diaphragm, stomach and abdominal musculature..vomiting