Pre Operative Care

Question 1

Fluid Requirements

Answer 1

20 – 30ml/kg/day water, 1mmol/kg/day Na, 1mmol/kg/day K, 50-100g/day Glucose.

Question 2

At Risk Patients of Fluid Imbalance

Answer 2

Acute presentation of diarrhoea and vomiting, reduced fluid intake, Elderly
patients and patients with reduced renal reserve, Drugs that impair renal responses to fluid changes (e.g. Diuretics), Patients with low body weight/Children (↓Overall total body fluid)

Question 3

Isotonic Saline

Answer 3

(0.9%) prevents rapid cellular shifts during rehydration and excess sodium
excreted by the kidneys; Potassium (e.g. Sando-K) added if loss expected e.g. Vomiting,
Pancreatic or Small Bowel fistula

Question 4

Dextrose

Answer 4

useful in energy supplementation as well as raising intracellular volume (Glucose influx into cells, glucose metabolism produces water)

Question 5

Hartmann’s Solution

Answer 5

Lower sodium than Isotonic, contains Potassium, Lactate and Calcium

Question 6

Fluid Depletion

Answer 6

Fluid Depletion = %PCV from normal × 0.7 × Patient weight (kg)

Question 7

Signs of Fluid Depletion

Answer 7

Body weight on admission can also provide estimate of loss; Acute loss ≈ Water loss
o Serum Urea is raised disproportionally from Creatinine (UCR)

Question 8

How to rehydrate

Answer 8

Young, fit patients can receive 15% Body fluid volume by rapid infusion; Slower for elderly to
prevent acute overload
o NB: Body fluid volume = 60% Body weight
o Monitoring of Fluid optimisation – 1-hourly urine output; commonly used 0.5ml/kg/hr

Question 9

Vomiting

Answer 9

Postoperative Nausea and Vomiting related to general anaesthetic use; Therapy aims to replace Sodium, Potassium and Water loss via use of anti-emetics (e.g. Ondansetron, Metoclopramide) although not as monotherapy as there is no single effective drug),
avoidance of general anaesthetic
• Avoidance of Emetogenic drugs e.g. Nitrous Oxide, Opioids or use of less emetogenic anaesthetics e.g. Propofol

Question 10

Shock

Answer 10

Inadequate End-organ perfusion and tissue oxygenation; ↓BP, ↑HR,
Pallor/Cold/Clammy, Confusion, ↓Pulse pressure (SBP – DBP), ↓Urine output

Question 11

Approaching Shock

Answer 11

Airway and Breathing, Check Carotid/Femoral pulse, start 500ml IV crystalloids rapidly and recheck BP (Fluid challenge) and identify cause of shock
o Hypovolaemic – Lie flat, start high flow oxygen, repeat 500ml IV, Take FBC (Purple
tube), U&E (Orange tube), Clotting (Blue tube) and Cross-match, Arterial Blood Gases
and treat if Hyperkalaemia present (Insulin ± Dextrose)

Question 12

Managing Hypovolemia

Answer 12

Lie flat, start high flow oxygen, repeat 500ml IV, Take FBC (Purple
tube), U&E (Orange tube), Clotting (Blue tube) and Cross-match, Arterial Blood Gases and treat if Hyperkalaemia present (Insulin ± Dextrose)

Question 13

Managing Anaphylaxis

Answer 13

1:1000 Adrenaline IM, 100mg Hydrocortisone IV, 10mg
Chlorpheniramine IV; Repeat 5-10 minutes again if no improvement
▪ If Wheezy 5ml Salbutamol Nebs
▪ IV Adrenaline (1:10000) only for experienced clinician use

Question 14

Managing Septic Shock

Answer 14

Sepsis Six, Escalate ITU/CCOT; Inotropic Support (E.g. Noradrenaline)

Question 15

Managing Cardiogenic Shock

Answer 15

Morphine, ECG, Anti-arrhythmic, GTN, Aspirin if appropriate; Send ABG, FBC, U&E, Clotting, Troponin
▪ Fluid overload – CXR and Diuretics (e.g. IV Furosemide 40mg)

Question 16

Reasons for Fluid Overload

Answer 16

Seen because of Heart Failure, excessive IV therapy, massive transfusion (i.e. Transfusion Associated Circulatory Overload = TACO), high sodium intake (most drugs)

Question 17

Presentation of Fluid Overload

Answer 17

Presents with increased weight, Fluid in the third space (Peripheral and Pulmonary Oedema,
Ascites), Paroxysmal Nocturnal Dyspnoea and raised JVP

Question 18

Management of Fluid Overload

Answer 18

Managed by stopping excessive Intravenous therapy, Diuretics, Treatment of underlying cause (e.g. Heart failure, AKI), Fluid restriction (1L/day + Urine output)

Question 19

Uses for blood transfusion

Answer 19

Used in the treatment of symptomatic anaemia (Pallor, Fatigue, Hypotension,
Tachypnoea); Higher threshold if not actively
bleeding or about to undergo procedure

Question 20

Blood

Answer 20

One unit increases Hb by 1g/dL in

70kg adult, 1 unit = 350ml of Pack Red cells

Question 21

Autologous Transfusion

Answer 21

2 units drawn

preoperatively and stored up to 6 weeks

Question 22

Cell Salvage

Answer 22

Collection of shed blood,

heparinised, spun with saline and repackaged

Question 23

Avoiding Transfusion

Answer 23

o Transfusion may be avoided by treating Anaemia and Coagulopathy preoperatively, stopping factors which increase bleeding, Procoagulants, Erythropoietin
o Antifibrinolytic Procoagulants (e.g. Tranexamic acid) – Inhibition of Plasminogen and
Plasmin reduces clot breakdown

Question 24

Platelets

Answer 24

One unit increases count by 30-60 x 109/L in 70kg adult, should be ABO compatible

and Rh matched in females of child-bearing age

Question 25

Fresh Frozen Plasma

Answer 25

Contains all coagulation factors except platelets; Will raise clotting factors by 1% in 70kg adult, 5-10ml/kg given, should be ABO compatible and Rh matched in females of child-bearing age

Question 26

Cryoprecipitate

Answer 26

Fibrinogen, FVII and FVIII; ABO and Rh not relevant

Question 27

Nutrition for Surgery

Answer 27

Anticipate patients have higher than normal nutritional requirements (e.g. Severe Burns, Sepsis, Fistulas, Malignancy, Immunosuppression)

Question 28

Nutrition for Surgery: Assessment

Answer 28

Assessed by BMI, Triceps Skinfold Thickness, Grip Strength, Serum Albumin and Transferrin

Question 29

Effects of Malnutrition

Answer 29

Malnutrition leads to Poor Immunity, Albumin production, Wound healing, Skeletal Muscle Weakness (‘Critical Illness Myopathy’), and specific deficiency syndromes

Question 30

How can nutrition be supplemented

Answer 30

Nutrition can be supplemented by Oral, NG/NJ feeds, RIG/PEG Tube, or Parenteral Feed o TPN – Limited by Osmolality (If Peripheral) or Volume (if Central); Risks include Osmolality, lack of Glycaemic Control, Micronutrient Deficiencies, Liver Dysfunction, Cholestasis, Pancreatic Atrophy, Volume Overload o TPN patients require regular U/Es, Glucose, LFTs, Micronutrients (+ Mg, PO4, Mn, Cu)

Question 31

TPN

Answer 31

TPN is typically reserved for patients with Prolonged Post-Op Ileus, Acute Abdominal Sepsis, or any reason where the GI tract is unable to absorb nutrition (e.g. Extensive resection, Extensive RT damage, Extensive Crohn’s disease)

Question 32

Antibiotic Prophylaxis

Answer 32

Reduce risk of SSI, usually short course (1 – 3 doses); Important to have high circulating concentration at time of potential tissue contamination (hence given at Anaesthetic), clean wounds do not require Abx, High risk patients require extended course or specific Abx o E.G. Neutropaenic, Immunocompromised, Severely Malnourished

Question 33

Thromboprophylaxis

Answer 33

• Risk factors: Prolonged Anaesthetic time, LL or Pelvic Surgery, Immobility, Malignancy, Age, Dehydration, Obesity, DM, CVS disease, Inflammatory pathology, Oestrogen, PMH • Mechanical Thromboprophylaxis – TEDs, Flowtrons, or Pharmacological – Heparin or LMWH

Question 34

Surgical Drains

Answer 34

• Removal of existing collections, Prevent build-up of fluids, Prevention of life-threatening conditions (E.g. Neck drains after Thyroid Surgery) • Risks – Damage during insertion, Infection route, Pressure injury if suctioned, Failure to drain causing false sense of security

Question 35

Acid Base Balance

Answer 35

• Normal blood pH is 7.35 – 7.45; Must be seen with PaCO2 and Base Excess to determine cause • Base Excess = mmol/L of acid needed to titrate blood back to 7.4 if paCO2 was normal o Excess >2mmol/L =? Metabolic alkalosis, Deficit

Question 36

Anion Gap

Answer 36

Anion Gap = Na+ + K + − (Cl− + HCO3−) Anion Gap should be 8 -16mmol/L – Increased gap =? Metabolic acidosis; Can be used to differentiate between types of Metabolic Acidosis

Question 37

Normal Gap (↓HCO3-/↑Cl-) Metabolic Acidosis

Answer 37

Renal Tubular Acidosis (Loss of Bicarbonate) Diarrhoea/High output Ileostomy Pancreatic Fistula Excessive Saline therapy (Hyperchloraemic)

Question 38

High Gap (↑H+) Metabolic Acidosis

Answer 38

Lactic Acidosis (Hypoperfusion, Sepsis, Hepatic) Uraemia (Renal Failure) Ketones (DKA, ETOH) Drugs/Toxins (Aspirin, SNP)

Question 39

Metabolic Alkalosis Causes

Answer 39

Loss of H+ from Renal (Diuretics) and GI Tract (Vomiting, NG tube), ↑HCO3- reabsorption (Hypochloraemia), Administration of bases

Question 40

Respiratory Acidosis

Answer 40

Respiratory Failure/ Hypoventilation, Increased CO2 production (e.g. Sepsis, Malignant Hyperpyrexia), Rebreathing of CO2

Question 41

Respiratory Alkalosis

Answer 41

Hyperventilation of any cause; Stroke, Anxiety, Pulmonary Embolism, Pneumonia, Asthma, etc

Question 42

Analgesia

Answer 42

• Non-Opioid Analgesia – NSAIDs (e.g. Aspirin, Ibuprofen, Diclofenac), Paracetamol • Weak Opioids – Codeine, Dihydrocodeine, Tramadol • Strong Opioids – Morphine, Diamorphine • Adjuvants may be added as part of pain ladder – Antidepressants (e.g. SSRIs), Anti-convulsant, Muscle relaxants, Sedatives

Question 43

IV Administration

Answer 43

100% bioavailability but shortest half-life if bolus

Question 44

IM Administration

Answer 44

Provides localised effect, but might be inconvenient or painful; Reduced muscle bulk or variable blood flow might affect absorption and distribution

Question 45

Oral Administration

Answer 45

Might come in formulations for Modified Release to reduce number of doses a day; Might have interactions with food, affected by GI malabsorption

Question 46

Other forms of administration

Answer 46

Continuous Wound Infiltration, Topical (poor | absorption), Intrathecal (into CSF in the spinal cord), Rectal (useful in children)

Question 47

Routine Postoperative Care

Answer 47

• Routine Blood – FBC, U/Es to look for Anaemia (slow bleed or haemodilution), Leukocytosis (Infection); Monitor INR/Clotting if anticoagulated; Check Electrolytes for fluid management and AKI, especially if Renal disease, Cardiac or Major Vascular surgery, Nephrotoxic drugs • ECG rarely used routinely outside Post-cardiac surgery; Look for Ischaemia or Arrhythmia • CXR – Daily if Chest drains present on suction, after Drain Removal, or to check Positioning of newly placed lines

Question 48

Complications of Surgery in Pregnancy First Trimester

Answer 48

Teratogenic drugs avoided (E.g. Carbamazepine, Valporate, Tetracycline, Warfarin, ACE Inhibitors); Reduced LOS tone, risk of GOR/Aspiration

Question 49

Complications of Surgery in Pregnancy Second Trimester

Answer 49

Drugs may have adverse effects on foetal development and | metabolism; Increased susceptibility to UTI (Especially ascending)

Question 50

Complications of Surgery in Pregnancy Third Trimester

Answer 50

Drugs might induce labour; Displacement of abdominal viscera superiorly and posterior of gravid uterus; Appendix comes to lie into RUQ; Risk of Hypotension due to IVC compression (Avoid by positioning in slight lateral decubitus

Question 51

Risk of Miscarriage

Answer 51

Highest in first trimester; Can be induced by GA

Question 52

Oestrogen-containing Contraceptives

Answer 52

Increased risk of Thromboembolic disease; Risk related to existing comorbidities and extent of surgery o Low risk (e.g. Dental, Day Case, Minor Laparoscopic) – Continue o Medium risk (e.g. Abdominal, Orthopaedic, Major Breast) – Discontinue for at least 1/12 prior to Elective surgery; If Emergency, Full Thrombo`prophylaxis o High risk (e.g. Pelvic, LL Orthopaedic, Cancer) – Discontinue 1/12 prior to Elective; Extended Full Thromboprophylaxis if Emergency

Question 53

Progesterone-only formulations

Answer 53

can be continued – Little to no risk

Question 54

Anticoagulants

Answer 54

Warfarin to be stopped 5 days prior, Clopidogrel stopped 5-7 days prior

Question 55

Diabetes Mellitus

Answer 55

Susceptibility to Infection, Poor Wound Healing, Skin Pressure Necrosis, Associated complications of DM (Renal impairment, CVS disease) o Should be first on operating list where possible; Ketoacidosis in perioperative period is associated with very poor outcomes; Avoid at all costs

Question 56

Diabetes Mellitus | o Minor Surgery

Answer 56

Stop Preop Insulin if IDDM; Monitor sugar 4hrly, Restart when oral diet re-established

Question 57

Diabetes Mellitus | Major Surgery

Answer 57

Omit long acting Hypoglycaemics; Monitor sugar 4hrly, if >15mmol/L start IV Insulin regimen; If IDDM, Commence on IV Insulin S/S once NBM, and continue until normal diet; Restart insulin at half dose initially once oral diet

Question 58

Diabetes Mellitus Emergency Surgery

Answer 58

Postpone surgery to <20mmol/L unless emergent

Question 59

Previous MI

Answer 59

Non-urgent surgery should be delayed for 6/12 following acute MI where possible; Ensure normal CVS medication continued through surgery

Question 60

Previous CVA

Answer 60

Non-urgent surgery should be delayed 6/52 after infarcts; Omit Thromboprophylaxis if previous Haemorrhagic event, Avoid head-down positioning

Question 61

Smokers

Answer 61

Ensure well hydration; Thromboprophylaxis; Preoperative Chest Physio; Early mobilisation; Consider regional anaesthesia to assist in PT; Ensure post-op PT effective

Question 62

Renal Impairment

Answer 62

Avoid Hypovolaemia, Hypotension, Nephrotoxicity; Lower dose of drugs with Renal Elimination (E.g. Morphine, LMWH) o If on Dialysis – Dialysis on day before surgery; U/Es twice daily after major surgery

Question 63

Post-Operative Pyrexia

Answer 63

Defined as >38oc on 2 consecutive days or >39oc on any postoperative day

Question 64

5Ws of Postoperative Pyrexia

Answer 64

Respiratory = Wind (Postop 1-2), UTI = Water (Postop 3-5), VTE = Walking (Postop 4-6), Site infection = Wound (Postop 5-7), Iatrogenic/Drugs = “What did we do?” (Postop 7+) o Most common cause 48 hours post-op is Pyretic Response to surgery o Other causes – Abscesses, Foreign body, C diff colitis, Haematoma, Osteomyelitis o Investigations are 48 hours – FBC, CXR, MC&S, Blood and wound cultures

Question 65

Malignant Hyperpyrexia

Answer 65

Associated with halogenated anaesthetic and paralytics (particularly succinylcholine); Linked to Ryanodine Receptor (RYR) gene o Treated with Dantrolene; Depression of excitation-contraction coupling of skeletal muscle by binding to RYR o Also associated with Non-haemolytic transfusion reactions and TRALI

Question 66

Sepsis

Answer 66

=Life Threatening Organ Dysfunction due to dysregulated Host Response to Infection o Defined as increase in 2 points or more in SOFA score; Every increase adds 10% mortality; QSOFA is 2 or more of Hypotension, Altered Mental and Tachypnoea o Septic Shock – Underlying Circulatory and Cellular/Metabolic Abnormalities profound enough to cause increased mortality ▪ Persistent Hypotension requiring Vasopressors to achieve MAP>65 and Lactate >2mmol/L; Mortality in excess of 40%

Question 67

Sepsis presentation

Answer 67

Pyrexia, Rigors, Hypothermia, Nausea, Vomiting, Vasodilation, Warm peripheries; Bounding Pulse, Rapid Capillary Refill, Hypotension (Septic Shock)

Question 68

Sepsis Six

Answer 68

Maintenance of oxygen delivery, Blood cultures, IV Empirical antibiotics, Test for Serum Lactate and FBC, Volume resuscitation (±Hypervolaemia), Urine output measurement

Question 69

Sepsis Additional Management

Answer 69

Inotropic (+Vasodilatory) support, Organ support – Renal, Hepatic, Enteral support

Question 70

Acute Lung Injury (ALI)

Answer 70

• ALI – Acute onset, PaO2/FiO2 <300, CXR with bilateral infiltrates, PAWP <18mmHg, no evidence of raised left atrial pressures (not due to Heart failure) • May progress to ARDS – PaO2/FiO2 <200 • Management by prone ventilation, aggressive diuresis, early ultrafiltration

Question 71

Wound Infection

Answer 71

Most wound infections are due to commensal organisms e.g. S. aureus, S epidermidis; or GI tract organisms e.g. E coli, Pseudomonas from the biliary tree o Treat as septic shock; Investigate any pus/discharge for MC&S, Blood cultures, FBC o If no pre-existing infections – Treat with anti-staphylococcus antibiotics (e.g. Flucloxacillin), if immunocompromised use broad spectrum with anaerobic cover (e.g. Metronidazole and Cefuroxime); consider Vancomycin if MRSA is suspected, with drug plasma monitoring

Question 72

Wound Dehiscence

Answer 72

Breaking open of the incision along its suture; May be superficial (Skin and subcutaneous) or full thickness (Fascia or bone), may cause protrusion (Evisceration) o Most secondary to wound infection o associated with immunosuppression, malnutrition, steroid use, poor surgical technique or previous surgery, or intracavity pathology o If superficial, ensure wound is open and drain any pus, pack with absorbent dressing o If deep, cover exposed viscera with saline soaked dressing initially ▪ Resuturing or closure if appropriate; inappropriate in the presence of infection, immunocompromise, instability or intracavity pathology ▪ Closure by secondary intention ± Vacuum closure devices

Question 73

Post-Operative Haemorrhage

Answer 73

More commonly venous bleeding due to opening of venous channels or damage to liver/spleen – Non-pulsatile, low pressure and darker in colour but significant amount

Question 74

Primary Haemorrhage

Answer 74

Usually due to unsecured blood vessels; occurs immediately after surgery or continuation of intraoperative bleeding

Question 75

Reactionary Haemorrhage

Answer 75

First 24hrs; Might be due to improved post-operative | circulation and fluid volume

Question 76

Secondary Haemorrhage

Answer 76

Infection of wound leading to clot disintegration

Question 77

Post-Operative Haemorrhage management

Answer 77

• Managed with IV crystalloid replacement, direct compression (NB: Do not use tourniquets on limb wounds), emergency crossmatch for a minimum of 2 units o If bleeding is severe reoperation might be necessary for diagnosis o If reoperation is highly undesirable conservative management can be considered – Radiologically guided embolism, FFP infusions, Permissive Hypotension and ITU o Haematoma formation after vascular/flap/limb/neck surgery needs to be explored and evacuated to avoid ischaemia, compartment syndrome, flap failure etc