Peri-operative management Flashcards
What is the time frame for post operative nausea and vomiting?
Within 48 hours of surgery
What are the complications of post operative nausea and vomiting?
- Wound dehiscence
- Prolonged admission
- Electrolyte derangement
- Dehydration
- Aspiration
- Oesophageal rupture
- Malabsorption
- Emotional distress
What factors make up the APFEL score?
- Female gender
- History of post-operative nausea and vomiting
- Non-smoker
- Perioperative opioid use
What are the percentage risks of developing PONV for each score on the APFEL score?
- 0 = 10%
- 1 = 20%
- 2 = 40%
- 3 = 60%
- 4 = 80%
How do the following drugs work, what dose should be given, and when?
- Ondansetron
- Droperidol
- Dexamethasone
- Aprepitant
- Metoclopramide
- Ondansetron
- 5HT-3 inhibitor
- 4mg
- At induction- Droperidol
- 0.625-1.25mg
- D2 antagonist
- At the end of surgery
- Dexamethasone
- Unclear mechanism
- 6.6mg
- At induction
- Aprepitant
- Neurokinin-1 inhibitor
- 40mg
- Pre-induction
- Metoclopramide
- Dopamine D2 antagonist
- 25-50mg
- Induction
- Droperidol
A 66 year old lady with peripheral vascular disease is undergoing a left below-knee amputation.
What is the best way to prevent phantom limb pain?
- Epidural anaesthesia with heavy bupivacaine and fentanyl
- PCA fentanyl
- IV lidocaine infusion
- Femoral and popliteal block with perineural catheters and post-operative local anaesthetic infusion
- Spinal anaesthesia with isobaric bupivacaine and diamorphine
- Femoral and popliteal block with perineural catheters and post-operative local anaesthetic infusion
Intially pos-amputation the main problem is stump pain. Phantom limb pain develops later.
Acute stump pain is ideally prevented but can be managed with opioids.
Epidural anaesthesia has a greater risk of complications.
Lidocaine has unproven benefits.
Spinal anaesthesia only lasts for 12-24 hours.
Which of the following is an absolute contraindication to free-flap microsurgery?
- Smoking
- Obesity
- Age >65
- Sickle cell anaemia
- Thrombocytopenia
- Sickle cell anaemia, polycythaemia rubra vera, and other hypercoagulable states are absolute contraindications to free flap microsurgery as there is a high chance of anastomotic thrombosis and flap failure.
Smoking and obesity increase risk of flap failure, and are therefore relative contraindications
Age is not a contraindication, so long as the patient is fit to endure a long operation.
Thrombocytopenia is a relative contraindication for surgery but is correctable prior to the operation.
Which of the following is the best predictor of difficult facemask ventilation?
- Smoker
- Previous radiotherapy to the neck
- Obesity
- Dentures
- Mallampati 2
- Previous radiotherapy to the neck
Facemask ventilation is difficult in 1/20 patients.
The risk factors are:
- Obesity
- Snoring
- Edentulous
- Male worse than female
- Increasing age
- Beard
- Mallampati 3 and 4
- Poor jaw protrusion
- Radiation to the neck is the greatest risk factor
Which of the following is the least concerning risk factor for a peri-procedural stroke in patients with AF?
- Mechanical aortic valve
- CHADSVASC score >2
- Recent CVA
- Recent TIA
- Rheumatic heart disease
- CHADSVASC score >2
All of the others are significant risk factors for a peri-procedural stroke, along with a CHADSVASC score of greather than 3
Name four risk factors for intraoperative cardiovascular instability during resection of phaeochromocytoma.
- High plasma noradrenaline levels pre-operatively
- MAP of >100mmHg at induction
- Large tumour
- Postural hypotension after alpha blockade
What factors should be taken into account when considering a deprivation of liberties safeguarding application (DoLs)?
- The patient lacks capacity to consent to medical care
- The patient is confined to a certain location for a substantial amount of time
- The patient will be continuously monitored
- The patient is not allowed to leave the premises
What are the risk factors for post operative delirium?
- Pre-existing dementia
- Previous episodes of delirium
- Alcohol and drug use
- Age over 70 years old
- Sensory impairment
- Hypertension
- Psychological illness
- Major surgery
- Critical illness
What legal options are there for future decision making for patients with dementia?
- Advanced directive
- Lasting Power of Attorney for Health and Welfare
- Court-appointed deputy or representative
What criteria must be met for a patient to be deemed to have capacity?
- Understand the choice to be made and relevant information
- Retain the information in order to make a decision
- Weight up the information
- Communicate their decision
Remember capacity is assumed unless the patient is deemed not to be able to do any one of the above requirements
Can you name the three most common causes of dementia in the United Kingdom?
- Alzheimer’s disease
- Vascular dementia
- Lewy body dementia
What are the features of venous ischaemia in a free flap?
- Warm
- Congested
- Blue
- Brisk capillary refill
- Rapid bleeding on pinprick
- Loss of venous doppler signal
What are the features of arterial ischaemia in a flap?
- Cool
- Pale
- Slow capillary refill
- No bleeding on pinprick
- Loss of triphasic doppler signal
What are clinical flap observations for post-operative recovery?
- Flap colour
- Capillary refill
- Skin turgor
- Skin temperature
- Bleeding on pinprick
- Transcutaneous Doppler signal
What are the common causes of free flap failure?
- Vessel trauma, thrombus or spasm
- Anastomotic failure
- Venous compression or thrombus
- Oedema
How can free flap perfusion be improved during surgery?
- Normothermia
- Normovolaemia
- Vasodilatory anaesthetic agents
- Usually the flap is fully dilated so this doesn’t usually help very much as you end up getting steal phenomenon by dilating the systemic vessels and diverting blood away from the flap itself
- Sympathetic blockade
- Minimise handling of free flap to avoid vasospasm
Which surgeries are particularly prone to causing PONV?
Breast
Eye
ENT
Gynaecological
Laparotomy and laparoscopy
Craniotomy
GU
Shoulder
Thyroid
What are the principle risk factors for venous thromboembolism in patients undergoing lower limb orthopaedic surgery?
Previous VTE
Malignancy
Known thrombophilia
Combined oral contraceptive
Hyperviscosity
Obesity
Pregnancy
Prolonged immobility
What are the features of Lee’s Revised Cardiac Risk Index?
High risk surgery
Coronary artery disease
Congestive heart failure
Cerebrovascular disease
Diabetes on insulin
Creatinine >177
0 = 0.4% risk of major cardiac complication
1 = 0.9%
2 = 6.6%
>2 = 11%
A venturi mask with an entrainment ratio of 1:9 is delivering 6 litres per minute of 100% oxygen.
What FiO2 is the patient receiving?
28.9%
For every 1 litre of pure oxygen the patient receives 9 litres of entrained room air
Therefore 6 litres 100% O2 and 54 litres 21% room air
Total oxygen = 6 litres + (54x0.21) = 17.34 litres
Total flow = 60 litres
FiO2 = 17.34/60 = 28.9%
Why might a thyroidectomy patient be agitated and short of breath in the immediate postoperative period?
- Neck haematoma
- Laryngeal oedema
- Recurrent laryngeal nerve palsy
- Laryngospasm
A 70 year old female presents to pre-assessment a month before elective knee replacement. She is found to be anaemic with Hb 97. What should you do?
Postpone the operation and refer for investigation of anaemia
Preoperative anaemia is an independent risk factor for postoperative mortality and morbidity in any elective surgery.
Patients also have:
- increased length of stay
- slower recovery
- worse outcome
What are the different classes of commonly used chemotherapy agent?
Anti-metabolites
- Methotrexate
- 5-fluorouracil
Topoisomerase inhibitors
- Doxorubicin
Anti-microtubule agents
- Paclitaxel
Alkylating agents
- Cisplatin
- Cyclophosphamide
Hormones
- Anastrazole
- LHRH analogues
Tyrosine kinase inhibitors
- Trastuzumab
What are the respiratory complications of chemotherapy with anaesthetic implications?
- Pneumonitis
- Pulmonary embolism
- Pneumonia
What are the cardiac complications of chemotherapy of relevance to the anaesthetist?
- Arrhythmias
- Cardiac failure
- Myocardial infarction
- Labile blood preassure
- Cardiomyopathy
- Myocarditis and pericarditis
What are the haematological complications of chemotherapy of relevance to the anaesthetist?
- Anaemia
- Thrombocytopenia
- Neutropenia
What are the hepatic complications of chemotherapy of relevance to the anaesthetist?
- Hepatocellular necrosis
- Cirrhosis
- Fibrosis
- Cholestasis
What are the neurological complications of chemotherapy of relevance to the anaesthetist?
- Peripheral neuropathy
- Seizures
- Encephalopathy
- Vocal cord palsy
- Autonomic neuropathy
How can the pulmonary toxicity associated with bleomycin be reduced?
Avoid oxygen and only use as little oxygen as possible
Which chemotherapeutic agent is most associated with neurological toxicity?
Vincristine
Why use neo-adjuvant chemotherapy?
Improve chances of survival
Increase likelihood of complete resection
Reduce the amount of surgical resection required
Which antiemetics are safe in Parkinson’s disease?
- Domperidone
- Ondansetron
- Cyclizine
Which Parkinson’s medications can be given parenterally?
- Apomorphine can be given subcutaneously
- Can cause severe hypotension
- Emetogenic
- Rotigotine can be given transdermally
- Not suitable for those on very high dose regimes
What are the main classes of drugs used to treat Parkinson’s disease?
- Dopamine agonists
- Pramipexole
- Ropinirole
- Rotigotine
- Apomorphine
- Dopamine precursors
- Levodopa
- Monoamine oxidase B inhibitors
- Selegiline
- Catechol-O-methyl transferase inhibitors
- Entacapone
- Glutamate antagonists
- Amantadine
What is the triad of parkinsonism?
- Bradykinesia
- Muscle Rigidity
- Resting tremor
What are the other features of Parkinson’s disease?
- Constitutional
- Depression
- Fatigue
- Insomnia
- Constipation- Motor
- Shuffling gait
- Dysphagia
- Quiet speech
- Hypomimia
- Instability
- Micrographia
- Neuropsychiatric
- Poor attention
- Dementia
- Autonomic
- Postural hypotension
- Sialorrhoea
- Urinary dysfunction
- Sexual dysfunction
- Motor
What are the components of the STOP BANG score?
Snoring
Tired during the day
Observed to have apnoeic episodes
Pressure (hypertension)
BMI >35
Age >50
Neck Circumference >40cm
Gender (male)
These are all yes/no answers scoring one point each. A score of 5 or more suggests moderate to severe sleep apnoea is highly likely.
What are the treatment options for sleep apnoea?
Weight loss
Smoking cessation
Abstaining from alcohol
Exercise
CPAP to manage symptoms
What are the risk factors for sleep apnoea?
Patient factors
Obesity
Age 40-70
Male gender
Neck circumference >40cm
Pregnancy
Craniofacial abnormalities
Neuromuscular disease
Tonsillar/adenoidal hypertrophy
Lifestyle factors
Smoking
Alcohol intake
Sedentary lifestyle
Unemployment
How can sleep apnoea be diagnosed?
Sleep polysomnography
STOP BANG questionnaire
Oxygen desaturation index
High clinical suspicion
What Apnoea-Hypopnoea Index or AHI score corresponds to each level of severity of OSA?
Mild - >5
Moderate - >15
Severe - >30
AHI is calculated as (total number of hypopnoeas + total number of apnoeas) divided by total sleep time in hours
What are the benefits of long term CPAP use in sleep apnoea?
Improved quality of life
Improved cardiac function
Improved daytime somnolence
Reduced plately aggregation
Reduced cardiovascular events
Reduced cerebrovascular events
Reduced pulmonary hypertension
Reduced depression
What are the components of the CHADS-VASc score and how much do they score?
Congestive heart failure - 1 point
Hypertension - 1 point
Age >75 - 2 points
Age 65 - 74 - 1 point
Diabetes - 1 point
Stroke or TIA history - 2 points
Sex (female) - 1 point
Vascular disease including MI - 1 point
CHADS-VASc score - %risk of stroke per year
0 - 0.2%
1 - 0.6%
2 - 2.2%
Benefit of anticoagulation of AF greatly exceeds risk for scores of more than 2
What is a Metabolic Equivalent of Task?
This is a ratio scale comparing different levels of exertion in terms of how much oxygen is consumed per minute, per kilo of body weight
One metabolic equivalent is the oxygen consumption of a resting, fasted adult
It is around 3.5ml/kg/minute
If you want to undergo major surgery, you should be able to perform at least 4 METs
This is approximately equal to climbing a flight of stairs
What is anaerobic threshold?
During exercise muscles use more ATP
Mitochondria use more oxygen to produce ATP
Oxygen extraction from the blood increases
The cardiovascular system increases cardiac output and reduces systemic vascular resistance to meet demand
This is helped by muscles (such as the calves) pumping venous blood back to the right side of the heart
Minute ventilation increases to blow off extra CO2 and supply more oxygen
As workload increases, the anaerobic threshold is reached where the ability to supply ATP through aerobic metabolism is exceeded
This results in lactic acid production and a sudden jump in CO2 release as bicarbonate is used to buffer the acid
An anaerobic threshold below 11mlO2/kg/min is associated with poor postoperative outcomes.
What parameters are measured during CPET?
Power
Oxygen consumption (VO2)
CO2 production (VCO2)
Respiratory exchange ratio
Anaerobic threshold
Heart rate
ECG and ST analysis
NIBP
Oxygen pulse (VO2/HR)
Minute ventilation
Tidal volume
Respiratory rate
What are the objective measures of exercise capacity?
- CPET
- Questionnaires such as Duke activity status index
- Incremental shuttle walk - Patients walk continuously between two cones 9m apart, and gradually need to increase pace to reach the cone on time
- Six minute walk test - Distance walked in six minutes on the flat
- Step test - Step up onto a 20cm step and down again for three minutes
What are the contraindications to CPET?
As always - categorise contraindications into ‘absolute’ and ‘relative’.
Absolute
Acute MI
Unstable angina
Uncontrolled or symptomatic arrhythmia
Active endocarditis
Acute myo- or pericarditis
Severe symptomatic aortic stenosis
Uncontrolled heart failure
Suspected aortic aneurysm
Uncontrolled asthma
Sats <85% at rest on room air
Relative
Untreated left main stem disease
Asymptomatic severe aortic stenosis
Severe hypertension at rest
Hypertrophic cardiomyopathy
Pulmonary hypertension
Acute DVT
Abdominal aortic aneurysm more than 8cm
CPET is deemed safe with a mortality of less than 5 in 100,000.
Which CPET-derived variables are associated with poor outcomes?
VO2 peak of less than 15ml O2/kg/minute is associated with poor outcomes post operatively
Anaerobic threshold of less than 11ml O2/kg/min is considered a contraindication to major surgery
