Anaesthetics and Peri-op Care Flashcards
Describe the American society of anaesiologists classification for surgery
- ASA I – normal health patients – non-smoking and no or minimal alcohol use
- ASA II – mild systemic disease – current smoker, social alcohol drinker, pregnancy, obesity (30-40), well controlled diabetes/hypertension and mild lung disease
- ASA III – severe systemic disease – poorly controlled diabetes/hypertension, COPD, morbid obesity (>40), hepatitis, alcohol dependence or abuse, pacemaker, , MI within last 3 months, CVA, ESRD undergoing dialysis and moderate reduction in ejection fraction.
- ASA IV – severe systemic disease that is constant threat to life – MI in last 3 months, CVA, severe valve dysfunction, severe reduction in ejection fraction, sepsis, DIC, ARD, and ESRD not undergoing dialysis.
- ASA V – moribund patient who is not expected to survive without the operation – ruptured AAA, massive trauma, intracranial bleed, ischaemic bowel with significant cardiac pathology or multiple organ/systemic dysfunction
- ASA VI – declared brain dead patient where organs are being removed for donor purposes
What pre medications might you consider for a nervous or young patient prior to surgery?
In particularly nervous patients or young patients a benzodiazepine is sometimes used to help calm their nerves around 2 hours prior to commencing surgery.
Why might ranitidine or an PPI be given to patients prior to surgery?
In those at high risk of aspiration antacids may be necessary such as a PPI or ranitidine.
What common side effect from epidurals can also be a sign of something much more dangerous?
Heavy leg feeling is a relatively normal side effect, but you must be very careful
This is also a sign of epidural abscess or haematoma which compresses the spinal cord and causes ischaemia. If heavy legs do not go away upon stopping the epidural, then must call anaesthetist.
What are the two main contraindications to epidurals?
Note epidurals and spinal blocks are contraindicated by use of anticoagulants and local infections.
What is propofol and what are its adverse effects?
Propofol – GABA receptor agonist causing rapid onset anaesthesia. Rapidly metabolised with proven anti-emetic properties. Moderate myocardial depression and widely used for maintaining sedation on ITU total IV anaesthesia and day case surgery.
What is sodium thiopentone and what are its adverse effects?
Sodium thiopentone – GABA agonist with extremely rapid onset so used for rapid sequence induction, marked myocardial depression, metabolites build up quickly, unsuitable for maintenance infusion and little analgesic effect. Can cause laryngospasm.
What is ketamine and what are its adverse effects?
Ketamine – NMDA receptor antagonist and can be used for induction of anaesthesia. Has moderate-strong analgesic properties and produces little myocardial depression so is suitable for those who are haemodynamically unstable. Can induce dissociative anaesthesia resulting in nightmares.
What is etomidate and what are its adverse effects?
Etomidate – GABA agonist with favourable cardiac safety profile but no analgesic properties, unsuitable for maintaining sedation as use may result in adrenal suppression. Post-operative vomiting Is common.
What is halothane and what are its adverse effects?
Halothane – inhaled – GABA and Glycine agonist. Adverse effects include hepatotoxicity, myocardial depression and malignant hyperthermia
What is Suxamethonium and what are its adverse effects?
Suxamethonium – depolarising neuromuscular blocker that inhibits action of acetylcholine at neuromuscular junction. Degrades by plasma cholinesterase and acetylcholinesterase. Fastest onset and shortest duration of all muscle relaxants. Causing one generalised muscular contraction prior to paralysis. Adverse effects include hyperkalaemia, malignant hypertension, and lack of acetylcholinesterase.
Name some non depolarising neuromuscular blockers and their side effects
Atracurium – non depolarising neuromuscular blocker, duration of action is 30-45 minutes, not excreted by kidney or liver but by tissues and can be reversed via neostigmine.
Vecuronium – non depolarising neuromuscular blocker, duration of action is 30-40 minutes, degrades by liver and kidney and effects prolonged in organ dysfunction. Can be reversed by neostigmine
Pancuronium – non depolarising neuromuscular blocker, onset of action in 2-3 minutes and duration of 2 hours, effects partially reversed with neostigmine.
What is a depolarising vs non depolarising muscle relaxants
Depolarising – binds to nicotinic acetylcholine receptors resulting in persistent depolarisation of the motor end plate. Cannot be reversed.
Non depolarising – competitive antagonist of nicotinic acetylcholine receptors. Can be reversed and cause hypotension.
What is malignant hyperthermia?
Occurs after administration of anaesthetic agents that result in hyperpyrexia and muscle rigidity. Occurs due to excessive release of Ca from sarcoplasmic reticulum of skeletal muscles. Susceptibility is inherited in autosomal dominant pattern.
What are the common causative agents of malignant hyperthermia?
Halothane
Suxamethonium
Antipsychotics causing neuroleptic malignant syndrome has a similar aeitiology
What are the clinical features of malignant hyperthermia?
Muscle rigidity
Hyperpyrexia
Raised creatinine kinase
How should you investigate for malignant hyperthermia?
Contracture test with halothane and caffeine - muscle biopsy
How is malignant hyperthermia managed?
Dantrolene – prevents Ca release from sarcoplasmic reticulum
What is the ERAS protocol?
This was designed to help patients recover more quickly from surgery
Pre-operative
• Patient education regrding their surgery and what to expect
• Ensuring good health prior to surgery
• Optimal pre-operative fasting guidelines
Intra-operative
• Using multimodal and opioid sparing analgesia
• Multimodal postoperative nausea and vomiting prophylaxis
• Minimally invasive surgery
• Goal directed fluid regime
Post-operative
• Ensure adequate pain control and early ambulation
• Early oral intake
• Multi-disciplinary patient follow up including in the post-acute phase
What should be done in the pre admission clinical appointment prior to surgery?
Pre admission clinic appointment to address medical issues
• History – PMHx, DHx and SHx (including anaesthetics history) most important, also neck and jaw mobility for intubation
• Examination – cardio respiratory (inlcuding airway classification), neck and jaw
• Baseline blood tests – FBC, U&Es, LFTs, Clotting screen and group and save
• Urine analysis
• Pregnancy test
• MRSA swab – all patients (nasal and skin lesions or wounds)
• ECG/Chest X-ray
What are the rules regarding food and liquid prior to surgery?
• Stop eating – 6 hours before
• Stop dairy products (including tea and coffee) – 6 hours before
• Stop clear fluids – 2 hours before
If aspiration were to occur this can lead to aspiration pneumonitis (due to the gastric acid) or pneumonia.
What drugs need to be modified prior to surgery?
Drugs to stop can be remembered using the phrase CHOW
- Clopidogrel – 7 days before (aspirin usually continued unless large bleeding risk)
- Hypoglycaemic medication (see below)
- Oral contraceptive pill or HRT – 4 weeks before, restart 2 weeks after
- Warfarin and DOACs– stopped 5 days prior and commenced on enoxaparin. INR must be less than 1.5 for surgery to go ahead otherwise reverse with vitamin K
- Anticonvulsants – give as normal pre-op then IV or NG until able to take orally again
- Beta-blockers and Digoxin – continue as normal
- Thyroid medication – must be euthyroid prior to surgery
- Omit all ACEi., ATBs and NSAIDs but continue other hypertension medications
- Lithium – omit
Never stop dual antiplatelet/anticoagulation therapy without specialist advice.
What should be done with steroids prior to surgery?
Steroids must be continued as if stopped this could lead to Addisonian crisis, may even require extra doses
Are there any drugs that need starting prior to surgery?
Enoxaparin and TED stockings (unless vascular patient)
Antibiotic prophylaxis for any surgery involving orthopaedic, vascular or GI.
How should a type 1 diabetic be managed prior to surgery?
Should be on the morning list
Night before surgery give all normal insulin and continue giving 80% of basal insulin including morning of the surgery
Morning of surgery withhold bolus short acting insulin (unless on PM list) and start on sliding scale insulin infusion
While nil by mouth give 125ml/hour of 5% dextrose and check BM every 2 hours.
Continue this until they can eat again and then give their SC insulin just before a meal and stop their IV insulin just after their meal.
How should type 2 diabetes be managed prior to surgery?
If controlled with diet, then no action required
If on oral medications then stop metformin on the morning of the surgery and stop oral hypoglycaemic drugs 24 hours before the op. Patient commenced on IV insulin pump for surgery and given IV 5% dextrose and post operatively managed same as type 1.
When is bowel prep required prior to surgery?
Bowl prep should only be given if surgery involves left colon, sigmoid or rectum/anus. They should be given a phosphate enema the morning of the op.
Who are the high risk VTE groups in surgery?
High risk VTE surgical groups
• Hip/knee replacement
• Hip fracture
• General anaesthetic and surgical duration> 90mins
• Surgery of the pelvis or lower limb with general anaesthesia and surgical duration > 60mins
• Acute surgical admission with inflammatory or intra-abdominal condition
• Surgery with significant reduction in mobility
What are the risk factors for VTE intra- or post surgery?
- Active cancer/chemotherapy
- Aged > 60
- Known blood clotting disorder
- BMI > 35
- Dehydration
- One or more significant medical comorbidities such as heart, metabolic, endocrine, respiratory, infections and inflammatory conditions
- Critical care admission
- Use of hormone replacement or COCP
- Varicose veins
- Pregnant or less than 6 weeks post-partum
How can VTE prophylaxis be administered mechanically?
Mechanical
- Correctly fitted anti-embolism stockings 9 thigh or knee height (CI in peripheral vascular disease)
- Intermittent pneumatic compressions device
- Mobilising as soon as possible
How can VTE be administered pharmacologically?
Pharmacological
- Fondaparinux SC injection
- LMWH – enoxaparin (reduce doses in severe renal impairment)
- Unfractionated heparin – used in chronic kidney disease
All surgical patients should at least have anti-embolism stockings
High risk patients require pharmacological methods in conjunction
How are elective hip, knee and fragility fractures of the pelvis managed in regard to VTE prophylaxis?
- Elective Hip – LMW heparin for 10 days followed by aspirin for 1 month OR LMWH for 1 month combined with anti-embolism stockings until discharge OR Rivaroxaban.
- Elective knee – Aspirin for 14days OR LMWH for 14 days with anti-embolism stockings until discharge OR rivaroxaban
- Fragility fractures of the pelvis – LMWH for a month after surgery OR fondaparinux starting 6 hours after surgery
Why is perioperative thermoregulation required?
Patients at particular risk of hypothermia due to large areas of body and internal body exposed, anaesthesia prevents normal physiological reactions to cold and anaesthetic drugs directly.
What are the problems with hypothermia in the surgical setting?
Hypothermia is dangerous as it causes poor clotting, prolonged recovery from anaesthesia, reduced wound healing, poor immune response to infection (due to poor healing and reduced immune cells accessing skin) and shivering which drastically increases metabolic rate.
What are the main risk factors for hypothermia in the surgical setting?
Risk factors for perioperative hypothermia
• ASA grade 2 or above
• Major surgery
• Low body weight
• Large volumes of un-warmed infusions – crystalloid or blood
How is hypothermia managed in the pre-, intra- and post- operative period?
Pre-operative management – test temperature 1 hour before surgery, if <36 then use active warming should be used immediately, If equal to or greater than then can wait until 30 minutes. Patients should not be moved to the theatre until temperature is > 36 unless time critical surgery
Intraoperative management – regular central temperature checks should be made. If surgery will last > 30mins then active warming should take place. Fluid volumes > 500ml should be warmed and all blood products. Intraoperative hyperthermia is almost always due to over warming as anaesthesia blunts the febrile response
Post-operative management – initially temperature documented in recovery room and then again, every 15minutes until ward transfer. Do not transfer if temperature is < 36. Patients are more likely to show a hyperthermia due to anaesthetic drugs being eliminated from their body.
Why are antibiotics required pre-operatively and when are they administered?
Antibiotics are often given in a single dose prior to commencing surgery as wound infection occurs in 20% of elective GI surgery and up to 60% of emergency surgeries. Additional doses can be given if high risk or prolonged procedure.
IV antibiotics should be given 30 minutes prior to surgery
Antibiotics should cover anaerobes and coliforms
What is the WHO surgical safety checklist?
Three phases of an operation
- Before induction (sign in)
- Before incision of the skin (time out)
- Before patient leave the room (sign out)
At each phase a checklist coordinator should confirm the team has completed a list of tasks before proceeding.
Before induction:
• Patient identity confirmed as well as surgical site, procedure and consent
• Site is marked
• Anaesthesia safety check completed
• Pulse oximeter on patient and functioning
• Allergies?
• Difficult airway/aspiration risk
• Is there a risk of blood loss > 500ml (7ml/kg in children)
What is NG feeding and what are the contraindications?
Nasogastric feeding (NG) Tube through the nose and into the stomach. Must confirm correct placement via low pH aspiration or CXR. Safe to use with patient with impaired swallow. Contraindicated following head injury due to risks associated with insertion.
What is NJ feeding and what are the contraindications?
Nasal Jejunal feeding (NJ)
Avoid food pooling in stomach, but more technically complicated than an NG tube and easiest if done intraoperatively. Safe to use following oesophagastric surgery.
What nutrition options are there other than NG feeding?
Nasal Jejunal feeding (NJ)
Avoid food pooling in stomach, but more technically complicated than an NG tube and easiest if done intraoperatively. Safe to use following oesophagastric surgery.
Feeding Jejunostomy
Surgically sites feeding tube and can be kept long term, low risk of aspiration and so safe following upper GI surgery. Main risks are that of tube displacement and peritubal leakage immediately following insertion carrying risk of peritonitis.
Percutaneous endoscopic gastrostomy (PEG)
Combined endoscopic and percutaneous tube insertion, may not be technically possible is those patients who cannot undergo successful endoscopy. Risks include aspiration and leakage at insertion site.
Total Parenteral nutrition
Definitive option in those who enteral feeding is contraindicated. Individualised prescribing and monitoring needed. Should be administered via central vein as it is strongly phlebotic.
What are the complications of parenteral feeding?
Complications
• Sepsis – always remove the line if suspected
• Long term use associated with fatty liver and deranged LFTs.
• Thrombosis which can result in pulmonary embolus or vena cava obstruction
• Metabolic imbalance – derranged plasma glucose, hyperlipidaemia, deficiencies, and acid base disturbance
• Mechanical – pneumothorax or embolism from IV-line tip
When is it safe for GI surgical patients to start eating?
It is generally considered safe for GI surgical patient to start taking enteral feeding from 24hours after their surgery.
What are the 3 parts to fluid management in surgical patients?
Break fluid prescribing down into 3 parts
- Resuscitation
- Maintenance
- Replacement
What specific recommendations are given for fluids in surgical patients?
Specific Recommendations for Surgery
• Hartman’s recommended as it is closest to physiological plasma levels
• Dextrose and dextrose/saline combinations are not recommended for surgical patients.
• Aim for oral fluids as soon as patient is capable to do so
• If patient oedematous then hypovolaemia should be treated first then fluid and sodium restrict
How common in post operative nausea and vomiting and how should it be managed?
This is extremely common, occurring in 25% of patients. Management should preferably involve multiple drug classes. The best treatment is IV anti emetics, usually a 5-HT antagonist such as ondansetron. Metoclopramide can also be used but beware of its pro-kinetic properties. Cyclizine is another good option.
What are the risk factors for post operative nausea and vomiting?
Risk Factors Female Age (being younger) Previous PONV Use of opioid analgesic Non-smoker Specific surgeries – intrabdominal, intracranial, squint, gynaecological, prolonged, and poor pain control Inhalational agents Dehydration Overuse of bag and mask ventilation
What are the 3 types of post operative haemorrhage and how are they managed?
Primary – continuous bleeding that started during surgery, replace blood loss with blood products and return to theatre if severe. Treat shock aggressively
Reactive – haemostasis achieved initially in theatres but rise in BP upon waking results in fresh bleeding. Replace blood and re-explore wound.
Secondary – usually as a result of infection occurring 1-2 weeks post operatively.
What is paralytic ileus?
There is no peristalsis resulting in pseudo-obstruction. It can occur in association with chest infection, myocardial infarctions, strokes, and AKI.
What are the risk factors for paralytic ileus?
Increased age Electrolyte derangement Neurological disorders Anti-cholinergic medication Opioid medication Pelvic surgery Extensive intra-operative handling Peritoneal handling Intestinal resection
What are the clinical features of paralytic ileus?
Clinical Features Delay in return to normal bowel Mechanical obstruction – no flatus, or faeces Bloating and distention Nausea and vomiting
What investigations should be done in paralytic ileus?
U&Es, Bone profile, FBC and CRP
CT abdomen and pelvis – rules out collections and leaks
How is paralytic ileus managed?
Electrolyte replacement
NBM
Encourage mobilisation
Reduce opiate analgesia
What are the two types of wound dehiscence?
Superficial dehiscence – skin wound alone fails, rectus sheath intact, often due to local infection, poorly controlled diabetes or poor nutritional status
Full thickness dehiscence – rectus sheath failure, termed burst abdomen, often secondary to raised abdominal pressure, poor surgical technique, or critically unwell patients.
Who is most at risk of wound dehiscence?
Those at particular risk • Elderly and male • Malnourished • Co-morbidities especially diabetes • Drugs – steroids • Smoking and/or obesity • Emergency surgery or abdominal surgery or long surgery • Infection • Uraemia • Haematoma • Warning sign – pink serous discharge
How is superficial dehiscence managed?
Washing out of the wound with saline and simple wound care
Allow wound to heal by secondary intention
How is full thickness dehiscence managed?
- Call for senior help immediately
- Insert bowel back into the abdomen and cover with sterile dressing
- Give IV broad spectrum antibiotics
- Reassure patient and give IV analgesia
- Return to theatre
What is an anastomotic leak?
Leakage of bowel contents into the peritoneum causing sepsis progresses to multi organ failure and death.
What are the risk factors for anastomotic leak?
Medications – corticosteroids and immunosuppressants Smoking or alcohol excess Diabetes mellitus Obesity or malnutrition Emergency surgery Longer intra-operative time Peritoneal contamination Oesophageal-gastric or rectal anastomosis
What are the clinical features for anastomotic leak?
Abdominal pain Fever Presentation 5-7 days post op Signs of sepsis Failure to progress or improve as expected Ileus
How should a suspected anastomotic leak be investigated?
CT scan with contrast
Routine bloods including cultures, group and save and cross match
Clotting screen
ABG
How are anastomotic leak managed?
NBM Start sepsis 6 Conservative management in small leaks (collections < 5cm) Large leak – drain percutaneously Exploratory laparotomy if septic
What are the early causes of post surgery pyrexia?
Early causes (0-5 days)
Blood transfusion
Cellulitis
Urinary tract infection (usually day 3-5)
Respiratory tract infection (usually day 1-2)
Physiological inflammatory reaction (usually within a day following the operation)
Pulmonary atelectasis
What are the late causes of post surgery pyrexia?
Late causes (> 5 days) Venous thromboembolism Pneumonia Wound infection Anastomotic leak
What are hypertrophic scars?
Excessive amounts of collagen within a scar. Nodules may be present histologically containing randomly arranged fibrils within and parallel fibres on the surface. The tissue itself is confined to the extent of the wound itself and is usually the result of a full thickness dermal injury. They may go on to develop contractures.
What are keloid scars?
Excessive amounts of collagen within a scar. Typically, a keloid scar will pass beyond the boundaries of the original injury. They do not contain nodules and may occur following even trivial injury. They do not regress over time and may recur following removal. Most common location is on the sternum.
What drugs can impair wound healing?
Drugs which impair wound healing: • Non-steroidal anti-inflammatory drugs • Steroids • Immunosuppressive agents • Anti-neoplastic drugs
What are the most common causes of post operative breathlessness?
- Atelectasis
- Pneumonia +/- aspiration pneumonitis
- LVF (secondary to overload or MI)
- Pulmonary embolism
- Pneumothorax
What is atelectasis?
Partial collapse of the small airways, usually due to airways becoming blocked from secretions.
What are the risk factors for atelectasis?
Age Smoking General anaesthetic use and duration of surgery Underlying lung or neuromuscular disease Prolonged bed rest Poor perioperative pain control
What are the clinical features of atelectasis?
Tachypnoeic usually around 72 hours following surgery Reduced oxygen saturations Fine crackles Reduced air entry Cough Tachycardic
How is atelectasis managed?
Sitting upright, deep breathing exercises and chest physiotherapy
Adequate pain control post operatively
Bronchoscopy as a last resort
What urine output should you be aiming for in a post surgical patient?
Should be aiming for an output of 30ml/kg/day in adults or >0.5ml/kg/h.
Why might a post surgery patient have oliguria?
- Blocked or misaligned catheter
- Poor fluid balance/oral intake
- AKI
- Urinary retention – check for palpable bladder
- Assess nephrotoxic drugs
What are the risk factors for surgical site infections?
- Extremes of age
- Poor nutritional status
- Diabetes, renal failure or immunosuppression
- Current smoker
- Perioperative shaving of site of incision
- Length of operation
- Foreign material in surgical site
- Insertion of surgical drain
- Poor closure of wound
What are the 3 types of surgical site infections?
Superficial Incisional Surgical Site Infection
Infection spreads through skin to subcutaneous tissue within 30 days of operation
Must meet one of 3 criteria:
1. Purulent discharge
2. Contains organisms from aseptically aspirated fluid, or tissue
3. Pain or tenderness, localised swelling, redness and heat
Deep Incisional Surgical Site infection
Skin, subcutaneous tissues, fascia and muscle within 30 days of operation or year of implant insertion
Meets one of 4 criteria:
1. Purulent drainage from the deep incision but not organ space
2. Contains organisms from aseptically aspirated fluid, or tissue
3. Pain or tenderness or spontaneous wound dehiscence
4. An abscess is found
Organ/Space Surgical Site infection
Infection within he viscera within 30 days of operation or year of implant insertion
Meets one of 3 criteria
1. Purulent drainage from a drain
2. Contains organisms from aseptically aspirated fluid, or tissue
3. An abscess is found
What organisms usually cause surgical site infections?
- Staphylococcus Aureus and coagulase staphylococcus
- Enterococcus species
- Escherichia Coliform
- Pseudomonas Aeruginosa
How should surgical site infections be managed?
Remove any sutures or clips to allow pus to be drained
IV antibiotics
What precautions can we take pre-, intra- and post- operatively to prevent surgical site infections?
- Pre-operative – showering, hair removal ONLY if necessary, appropriate theatre wear for staff and patient and antibiotic prophylaxis
- Intra-operative phase – hand decontamination, sterile gloves and gown, antiseptic skin preparation, a-pyrexical and oxygenation
- Post-operative – monitor wounds closely, especially those in hard to reach/see areas, use pads and relevant support to prevent sores and use and non-touch techniques when examining the wound
When should a gastrostomy be considered over NG feeding?
If gastric feeding for > 4 weeks consider long term gastrostomy
How long should ITU patients be fed for and what should you give if they are not absorbing food?
ITU patients should have continuous feeding for at least 16hours (24hours if on continuous insulin)
Consider motility agent in ITU or acute patients for delayed gastric emptying
How soon after insertion can a PEG be used and when can it be removed?
PEG can be used 4 hours after insertion but should not be removed until > 2 weeks after insertion.
How long should sutures be left in before they are removed?
Non absorbable sutures should be removed 7-14 days following surgery but this varies depending on the location:
• Face – 3-5 days
• Scalp, limb and chest – 7-10 days
• Hand, foot and back – 10-14 days
If a patients MRSA swab is positive prior to surgery how should they be managed?
MRSA suppression – Muciprocin nasal spray TDS for 5 days and Chlorhexidine gluconate cream OD for 5 days (apply all over but especially axilla, groin and perineum)
