Pre-operative Flashcards
Summarise NICE guidelines on pre-operative investigations - relevant for all surgeries regarding:
- existing medicines
- pregnancy tests
- SCD
- HbA1c
- Urine testing
- Echocardiography
- X-Ray
- Existing medicines- must be considered when offerring tests
- Pregnancy tests - ask sensitively if there is any chance she is pregnant and explain risks of anaesthetic on foetus; do a pregnancy test if there is any doubt; document all discussions
- Sickle cell disease/trait - don’t routinely offer testing but ask if they/family member have SCD; liaise with sickle cell team if known SCD
- HbA1c - offerred to diabetics only if they have not had it tested in the last 3 months
- Urine test - dipstick not routine; only offer microscopy/culture of urine if the presence of UTI would affect decision to operate.
- X-Ray - not routine
- Echocardiography - only offer in presence of murmur, cardiac symptoms or heart failure. Consider ECG first.
Summarise NICE guidelines on pre-operative investigations - based on ASA grades
ASA classification (American society of anaesthetists)
- I - 0.1% mortality
- II - 0.2-0.7% mortality
- III -1.8-3.5% mortality
- IV - 7.8-18.3% mortality
- V- 9.4-40% mortality
Add ‘E’ for emergency patient (x2 mortality)
POSSUM peri-operative risk scoring system
www.riskprediction.org.uk/index-pp.php
- Enter patient physiological and operative variables
- Mortality & morbidity risk
- -Pre-operative: risk discussion
- -Peri-operative: Need for Invasive monitoring?
- -Postoperative: Over 5% mortality risk should -> HDU/ITU post operative
Peri-operative disease management: explain the principles of peri-operative management of medical co-morbidities, including diabetes mellitus, hypertension, ischaemic heart disease, asthma, chronic obstructive pulmonary disease (COPD), patients on anti-coagulant medications and sickle cell disease
What are the reasons for conducting a pre-operative assessment?
- Increase efficiency and reduce costs of healthcare
- Identify and manage coexisting medical conditions
- Advise on changes to concurrent drug therapy - some antiplatelet or anticoagulant treatments need to be stopped several days before surgery
- Highlight potential anaesthetic difficulties
- Reduce chance of cancellation on the day of surgery
- Provide an opportunity to discuss treatment with the patient
- Plan admission and discharge arrangements
- Discuss the risks of the anaesthetic and surgery
- Provides opportunity for social arrangements and rehabilitation to be arranged in advance
Summarise types of anticoagulation therapy and how each works.
Vit K antagonists - e.g. warfarin - reduces hepatic vit K which y-carboxylates factors II, VII, IX, X
Direct oral anticoagulants -
- Thrombin inhibitors - e.g. dabigatran
- Factor Xa inhibitors - e.g. apixaban, rivaroxaban, edoxaban
Summarise the basics of bridging therapy for anticoagulants
Giving short acting anticoaglant usually LMWH, by injection for 10-12 days around time of surgery, when warfarin is interrupted and INR is out of range for therapeutic effect.
Interrupting warfarin is not necessary for minor procedures.
For surgeries that carry a significant bleeding risk, warfarin is stopped 5-6 days before surgery and bridging anticoag (LMWH) started 3 days before surgery with last dose 24hrs before surgery. Bridging resumed 24hrs after surgery and warfarin restarted at same time. Bridging continued for 4-6 days until INR is within therapeutic range.
Which patients are at high risk of VTE?
- Atrial fibrillation
- Mechanical heart valve
- Venous thromboembolism
Assessed with CHADS2 score - cardiac failure, hypertension, age, diabetes, stroke, VTE, TIA
Day surgery - recall criteria for the suitability of patients for day stay surgery
Social factors - whether the patient gives consent, has a carer present for 24hrs post-op
Medical factors - fitness (determined by pre-anaesthetic assessment not ASA), stable chronic conditions suitable(e.g. diabetes) but not unstable, obese suitable (if appropriate extra time, skilled assisstants and equipment), in OSA pt advised no opioids post-op and regional anaesthesia.
Surgical factors - if no risk of serious post-op complications, controlled
Aims of Pre-operative assessment (5)
- Contact with patient Targeted Hx and exams; investigations
- Assess risks of surgery vs current condition
- Explain techniques and post-op analgesia to pt
- Prescribe pre-medication
- Obtain consent
Components of history in pre-operative assessment.
- Anaesthetic history
- Co-morbidities
- CVS, GI, RS, Endocrine
- Drugs and recreational drugs + smoking (should have stopped for at least 1 month)
- Allergies
- Family history
AMPLE History
- Allergies
- Medications
- Past medical history
- Last eating and drinking
- Everything else - loose teeth, metal in body, reflux, smoking
What are some relevant disorders to anaesthesia?
- pseudo-cholinesterase deficiency
- porphyria
- myesthenia gravis
What should you do if a male patient has a Hb of 115g/L on pre-operative assessment?
Postpone surgery until anaemia has been investigated unless the surgery is urgent/life-saving.
- Preoperative blood transfusion is not appropriate in a patient with a Hb > 80.*
- In men Hb <130g/L*
- In women Hb <120g/L is anaemia*
General Exam for a pre-op assessment (4)
- Nutritional state
- Fluid balance
- Condition of skin/jaundice
- Temperature and regulation
Airway Exam for a pre-op assessment (3)
- Mouth opening (Mallampati score)
- Neck mobility
- Quality of teeth and anything else in the oral cavity
Describe the Mallampati scoring system. What other system can be used?
Mallampati - class I-IV
Wilson’s score - = 5 shows easy intubation
- Weight
- Head and neck movement
- Jaw movement
- Receding mandible
- Buck teeth
Respiratory Exam for a pre-op assessment
- Is there any cyanosis, dyspnoea?
- Are the lung fields clear?
- Pt in respiratory failure?
- Any Hx of asthma, COPD,
Circulatory Exam for a pre-op assessment
- BP, peripheral pulses, JVP/oedema, heart sounds; murmurs
- Is the patient in heart failure?
- Assess risk of IHD, HTN, arrhythmia –> if concerned perform ECG, CXR, ABG
(Arrhythmias can occur with propofol)
CNS Exam for a pre-op assessment. Describe GCS scoring.
- Are there any dysfunctional nerves, reflexes or senses?
- GCS (eye opening,motor response) - EMV 4,5,6
- Confusion, epilepsy or head injury
Metabolic and endocrine review pre-op assessment
- Renal failure? (acute or chronic)
- Liver disease? (effects on clotting or drug metabolism)
- Diabetes (consider insulin infusion for IDDM or NIDDM if long op)
- Thyroid and adrenal function
Haematology review for pre-op assessment
- Anaemia –> occult blood loss? sickle cell and other haemoglobinopathies, acute loss
- Clotting disorders –> liver disease, anticoagulant therapy
Which patients can desaturate quickly?
- Children - higher metabolic drive
- Pregnant
- Obese - lower FRC
Should antihypertensive medication be stopped prior to surgery?
Are antibiotics given 5 days in advance?
MOST antihypertensives should be continued until the day (including morning) of the surgery.
Antibiotics for surgical prophylaxis are given as a single dose close to the time of skin incision, usually during induction of anaesthesia. Patients may be prescribed topical decolonising regimes if MRSA positive.
