Pre Operative Care Flashcards
Fluid Requirements
20 – 30ml/kg/day water, 1mmol/kg/day Na, 1mmol/kg/day K, 50-100g/day Glucose.
At Risk Patients of Fluid Imbalance
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)
Isotonic Saline
(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
Dextrose
useful in energy supplementation as well as raising intracellular volume (Glucose influx into cells, glucose metabolism produces water)
Hartmann’s Solution
Lower sodium than Isotonic, contains Potassium, Lactate and Calcium
Fluid Depletion
Fluid Depletion = %PCV from normal × 0.7 × Patient weight (kg)
Signs of Fluid Depletion
Body weight on admission can also provide estimate of loss; Acute loss ≈ Water loss
o Serum Urea is raised disproportionally from Creatinine (UCR)
How to rehydrate
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
Vomiting
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
Shock
Inadequate End-organ perfusion and tissue oxygenation; ↓BP, ↑HR,
Pallor/Cold/Clammy, Confusion, ↓Pulse pressure (SBP – DBP), ↓Urine output
Approaching Shock
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)
Managing Hypovolemia
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)
Managing Anaphylaxis
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
Managing Septic Shock
Sepsis Six, Escalate ITU/CCOT; Inotropic Support (E.g. Noradrenaline)
Managing Cardiogenic Shock
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)
Reasons for Fluid Overload
Seen because of Heart Failure, excessive IV therapy, massive transfusion (i.e. Transfusion Associated Circulatory Overload = TACO), high sodium intake (most drugs)
Presentation of Fluid Overload
Presents with increased weight, Fluid in the third space (Peripheral and Pulmonary Oedema,
Ascites), Paroxysmal Nocturnal Dyspnoea and raised JVP
Management of Fluid Overload
Managed by stopping excessive Intravenous therapy, Diuretics, Treatment of underlying cause (e.g. Heart failure, AKI), Fluid restriction (1L/day + Urine output)
Uses for blood transfusion
Used in the treatment of symptomatic anaemia (Pallor, Fatigue, Hypotension,
Tachypnoea); Higher threshold if not actively
bleeding or about to undergo procedure
Blood
One unit increases Hb by 1g/dL in
70kg adult, 1 unit = 350ml of Pack Red cells
Autologous Transfusion
2 units drawn
preoperatively and stored up to 6 weeks
Cell Salvage
Collection of shed blood,
heparinised, spun with saline and repackaged
Avoiding Transfusion
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
Platelets
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
Fresh Frozen Plasma
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
Cryoprecipitate
Fibrinogen, FVII and FVIII; ABO and Rh not relevant
Nutrition for Surgery
Anticipate patients have higher than normal nutritional requirements (e.g. Severe Burns, Sepsis, Fistulas, Malignancy, Immunosuppression)
Nutrition for Surgery: Assessment
Assessed by BMI, Triceps Skinfold Thickness, Grip Strength, Serum Albumin and Transferrin
Effects of Malnutrition
Malnutrition leads to Poor Immunity, Albumin production, Wound healing, Skeletal Muscle Weakness (‘Critical Illness Myopathy’), and specific deficiency syndromes
How can nutrition be supplemented
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)
TPN
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)
Antibiotic Prophylaxis
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
Thromboprophylaxis
• 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
Surgical Drains
• 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
Acid Base Balance
• 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
Anion Gap
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
Normal Gap (↓HCO3-/↑Cl-) Metabolic Acidosis
Renal Tubular Acidosis (Loss of Bicarbonate)
Diarrhoea/High output Ileostomy
Pancreatic Fistula
Excessive Saline therapy (Hyperchloraemic)
High Gap (↑H+) Metabolic Acidosis
Lactic Acidosis (Hypoperfusion, Sepsis, Hepatic)
Uraemia (Renal Failure)
Ketones (DKA, ETOH)
Drugs/Toxins (Aspirin, SNP)
Metabolic Alkalosis Causes
Loss of H+ from Renal (Diuretics) and GI Tract (Vomiting, NG tube),
↑HCO3- reabsorption (Hypochloraemia), Administration of bases
Respiratory Acidosis
Respiratory Failure/ Hypoventilation, Increased CO2 production (e.g. Sepsis, Malignant Hyperpyrexia), Rebreathing of CO2
Respiratory Alkalosis
Hyperventilation of any cause; Stroke, Anxiety, Pulmonary Embolism,
Pneumonia, Asthma, etc
Analgesia
• 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
IV Administration
100% bioavailability but shortest half-life if bolus
IM Administration
Provides localised effect, but might be inconvenient or painful; Reduced
muscle bulk or variable blood flow might affect absorption and distribution
Oral Administration
Might come in formulations for Modified Release to reduce number of
doses a day; Might have interactions with food, affected by GI malabsorption
Other forms of administration
Continuous Wound Infiltration, Topical (poor
absorption), Intrathecal (into CSF in the spinal cord), Rectal (useful in children)
Routine Postoperative Care
• 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
Complications of Surgery in Pregnancy First Trimester
Teratogenic drugs avoided (E.g. Carbamazepine, Valporate, Tetracycline, Warfarin, ACE Inhibitors); Reduced LOS tone, risk of GOR/Aspiration
Complications of Surgery in Pregnancy Second Trimester
Drugs may have adverse effects on foetal development and
metabolism; Increased susceptibility to UTI (Especially ascending)
Complications of Surgery in Pregnancy Third Trimester
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
Risk of Miscarriage
Highest in first trimester; Can be induced by GA
Oestrogen-containing Contraceptives
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
Progesterone-only formulations
can be continued – Little to no risk
Anticoagulants
Warfarin to be stopped 5 days prior, Clopidogrel stopped 5-7 days prior
Diabetes Mellitus
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
Diabetes Mellitus
o Minor Surgery
Stop Preop Insulin if IDDM; Monitor sugar 4hrly, Restart when oral
diet re-established
Diabetes Mellitus
Major Surgery
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
Diabetes Mellitus Emergency Surgery
Postpone surgery to <20mmol/L unless emergent
Previous MI
Non-urgent surgery should be delayed for 6/12 following acute MI where
possible; Ensure normal CVS medication continued through surgery
Previous CVA
Non-urgent surgery should be delayed 6/52 after infarcts; Omit
Thromboprophylaxis if previous Haemorrhagic event, Avoid head-down positioning
Smokers
Ensure well hydration; Thromboprophylaxis; Preoperative Chest Physio; Early mobilisation; Consider regional anaesthesia to assist in PT; Ensure post-op PT effective
Renal Impairment
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
Post-Operative Pyrexia
Defined as >38oc on 2 consecutive days or >39oc on any postoperative day
5Ws of Postoperative Pyrexia
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
Malignant Hyperpyrexia
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
Sepsis
=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%
Sepsis presentation
Pyrexia, Rigors, Hypothermia, Nausea, Vomiting, Vasodilation, Warm
peripheries; Bounding Pulse, Rapid Capillary Refill, Hypotension (Septic Shock)
Sepsis Six
Maintenance of oxygen delivery, Blood cultures, IV Empirical antibiotics, Test for
Serum Lactate and FBC, Volume resuscitation (±Hypervolaemia), Urine output measurement
Sepsis Additional Management
Inotropic (+Vasodilatory) support, Organ support – Renal, Hepatic, Enteral support
Acute Lung Injury (ALI)
• 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
Wound Infection
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
Wound Dehiscence
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
Post-Operative Haemorrhage
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
Primary Haemorrhage
Usually due to unsecured blood vessels; occurs immediately after surgery or continuation of intraoperative bleeding
Reactionary Haemorrhage
First 24hrs; Might be due to improved post-operative
circulation and fluid volume
Secondary Haemorrhage
Infection of wound leading to clot disintegration
Post-Operative Haemorrhage management
• 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
