General principles of surgery - medical finals revision notes

1. General Principles of
Surgical Management
Christiane Riedinger September 2014

2. TOC
● Introduction and general points
● Pre-operative management
● Fluids
● Post-operative management

3. Introduction

4. Surgical Sieve: Grid for determining pathological causes
A – autoimmune
V – vascular
I – infective, inflammatory
T – traumatic
A – acquired
M – metabolic
I – iatrogenic
N – neurological, neoplastic, nutritional
C – congenital
D – degenerative, drugs
E – environmental, endocrine
P – psychosomatic

5. Anatomical Sieve: Causes of Obstruction
● Luminal
○ Obstruction due to content
○ Foreign body
○ Polyps
○ Intussusception
● Intramural
○ Inflammation
○ Tumours
○ Infarction
○ Strictures
● Extramural
○ Adhesions, hernias (for small bowel in particular)
○ Strangulation
○ Extrinsic compression by tumour, lymph node, other swelling, fluid
○ Volvulus

6. Overview of Investigations
● Testing of bodily fluids: e.g. urinalysis
● Haematological tests
● Radiological tests
● Special investigations

7. Overview of Treatments
● Conservative
○ Avoiding radical medical or surgical interventions
○ Least aggressive approach to treatment
● Curative
○ Medical
○ Surgical
● Palliative, i.e. not with the intent of cure
○ Management of symptoms
○ Pain relief

8. Pre-operative
Management

9. Pre-operative Assessment (1)
● Usually in pre-assessment clinic, exception: emergency admission
● Pre-operative clerking
○ Full Hx of presenting complaint and comorbidities
■ Relevant PMH: Diabetes, resp disease, CV disease, RA, rheumatic heart
disease or valvular disease, sicke cell disease
■ Past surgical Hx: Nature and complications
■ Past anaesthetic Hx: Intubation, aspiration, scoline apnoea, malignant
hyperpyrexia
■ Social Hx
■ Drug Hx: Need stopping: warfarin (convert to heparin), aspirin, clopidogrel
(antiplatelet drugs >10d prior), OCP (>6w prior). Need augmenting: steroid
replacement. Others: immunosuppression, diuretics (avoid pre-op
hypokalaemia), MAO-A inhibitors
■ Allergies: specifically Abx, anaesthetic agents, skin preparation
substances, wound dressings

10. Pre-operative Assessment (2)
○ Full examination, including general health and fitness for procedure
○ Ix
■ FBC +/- sickle cell screen, group&save or cross-match if risk of extensive
blood loss
■ Discuss with anaesthetist
○ Optimising health problems
○ Does indication for surgery still exist?
○ Potential marking of the surgical site

11. Mnemonic: ABCD LMNOPs
● Options for preoperative management
● Anaesthetist, Antibiotics
● Blood tests, bowel preparation
● Consent, CXR
● Drug chart, DVT prophylaxis
● ECG
● Fluids
● List, Lung function tests
● Mark the area
● Notes
● Operating theatre staff, contact for special equipment, radiology
● Physiotherapy
● Specialist nurses, e.g. breast or stoma
Reorganised by topics:
● Drugs: review which drugs to
continue and stop, allergies,
prophylaxis: DVT +/- Abx
● Pre-op check: anaesthetic review,
CXR, peak flow / lung function
tests, ECG
● Consent, mark area

12. NICE Guidelines for Pre-op Ix
● Chose Ix depending on age of patient, their health (healthy, CV, resp. or
renal comorbidities) and the severity of the procedure:
○ Minor (grade 1), e.g. abscess drainage or skin lesion excision
○ Intermediate (grade 2), e.g. hernia repair, arthroscopy, tonsillectomy
○ Major (grade 3), e.g. hysterectomy, thyroidectomy
○ Major+ (grade 4), e.g. joint replacement, lung surgery, colonic resect.
● List of Ix
○ CXR
○ ECG
○ FBC, clotting, U&E, glucose, group and save
○ Urinalysis
○ ABG
○ Lung function tests

13. ASA Criteria for Risk Assessment
● By American Society of Anesthesiologists ASA
● Grade I - no comorbidities mortality <0.1%
● Grade II - mild systemic disease 0.3%
● Grade III- Severe but not incapacitating systemic disease 2-4%
● Grave IV- Incapacitating life-threat. systemic disease 20-40%
● Grade V - Not expected to survive 24h +/- surgery >50%
● Other scoring schemes: APACHE, p-POSSUM (takes patient and
procedural factors into account)

14. Ethics Regarding Consent
● Consent needs to be informed and voluntary of a person with capacity, i.e. able to
understand, retain, weigh the information and convey their decision.
● 2 stage test: does person have an illness impairing their brain function? If yes, is
their capacity impaired? If no capacity: need to maxime first before other means
● BRAIN of informed consent = information that needs to be given
○ Benefits of procedure
○ Risks of procedure
○ Alternatives of procedure
○ Indications for procedure
○ Nature of procedure
● Treatment without consent is battery (civil/tort law), sued for fine (compare
negligence where needs to prove a breach of duty of care resulted in injury, also
results in fine from civil court, only crown if manslaughter)

15. Diabetes and Surgery: General
● Increased risk of
○ Infection
○ Peripheral vascular disease
○ Pressure sores
○ IHD
● Pre-op Ix
○ Urine for protein
○ Blood glucose
○ U&E including creatinine
○ ECG
● Stop oral hypoglyaemics or subcut insulin (esp. long-acting) the day before and replace
with Glu/insulin infusion

16. Diabetes and Surgery: Specific
● NBM, increased catabolic hormones that antagonise insulin make control more difficult
● Aim between 5-9mM
● Insulin dependence
○ Sliding scale insulin: dextrose/K+ + fast-acting insulin (Actrapid) depending on the
hourly BM stix result (need K+ otherwise insulin will cause hypokalaemia due to
promotion of cellular uptake)
○ Mixed bag of dextrose, potassium and insulin
● Oral hypoglycaemics
○ Omit dose on morning of the operation / day before and resume post-op
○ Measure BM and if too high, either give single doses of insulin or put on sliding
scale
● Diet control
○ Assess BM

17. Respiratory Disease and Surgery
● Asthma
○ Peak flow
○ Avoid surgery in times of exacerbation
● COPD
○ Increased risk of chest complications
○ Ix
■ CXR
■ Lung function tests, incl. peak flow before and after bronchodilators
■ ABG
○ Pre-op breathing exercises to improve ventilation and removal of secretions
afterwards
○ Advise to stop smoking 4w prior
○ Consider likely post-op ventilation and epidural analgesia to avoid
complications (e.g. due to opioids)

18. Cardiac Disease and Surgery
● Angina: optimise management prior to surgery and consider exercise
tolerance
● CABG/stenting/balloon angioplasty: should have improved the patient’s
cardiac function. Routine ECG with potential exercise or stress ECG to rule
out significant disease. Consider local anaesthesia if severe
● The criteria of fitness for surgery vary according to the nature of the
surgery, if to correct a comorbidity of heart disease criteria may be less
strict.

19. Steroid Therapy and Surgery
● Increased risk of
○ Delayed wound healing
○ Post-operative infections
○ Adrenal insufficiency => Addisonian crisis, cover with additional
perioperative steroids

20. Other Conditions and Surgery
● Bleeding diatheses: involve haematology, provide adequate clotting
factors, give additional thromboembolic prophylaxis if on anticoagulants for
risk factors (TED stockings, compression boots, early mobilisation).
○ Rapid reversal of warfarin: human prothrombin complex, FFP
● Obstructive jaundice: Vit K / human prothrombin complex / FFP, maintain
diuresis perioperatively with adequate fluids, consider effect of liver
impairment on drug metabolism, increased risk of infection
● Chronic renal failure: Uraemia inhibits platelet function => desmopressin
(stimulates VWF release from endothelium to improve pt function).
Consider effect of kidney impairment on drug metabolism, may need
naloxone to reverse opiate analgesia. Choose venous access carefully
(not on side of fistula!)

21. Antibiotic Prophylaxis
● Distinguish types of surgery
○ Clean surgery - risk of general vs. wound infection 2%
○ Clean/contaminated surgery - risk 3%/10%
○ Contaminated surgery - risk 6%/20%
○ Dirty/infected surgery - risk 7%/40%
○ Infections involving prosthetic implants => avoid contamination from skin
○ Can reduce post-op infection rate below 8-10% in dirty surgery!
● Choose Abx depending on type of surgery and patient related factors, e.g. heart valve
pathology predisposing to endocarditis
● Give IV Abx at induction of anaesthesia before tourniquet inflated, total 1-3 doses
● When to use: Prosthetics, vascular surgery, amputation of ischaemic limb, penetrating wounds
and fractures, organ transplants, high risk of contamination (biliary and alimentary tract)
● Choose Abx depending on site of surgery and anticipated infection
● Liaise with microbiologists

22. Fluid Treatment

23. Main Available IV Fluids
● Crystalloids = isotonic water and electrolytes
○ Hartmann’s
■ 131mM Na+, 111mM Cl-, 29mM Lactate, 5mM K+, 2mM Ca2+
■ Will distribute to interstitium and not stay IV for long (1/4 only as intravascular is ~
¼ of EC fluid)
○ Saline - isotonic 0.9%
○ 5% Glucose/Dextrose (like giving water as cannot give water on its own, would lyse red
cells in the blood)
■ Glu will be metabolised, fluid distributed evenly throughout all compartments
■ Water will go IC, so not useful for hypovolaemia
○ 50% Glucose
■ For hypoglycaemia (although better use 20% to avoid phlebitis)
● Colloids = suspended particles
○ Stay IV for longer
○ Pull fluid into plasma, use in trauma to replace plasma components
○ May interfere with clotting and cause anaphylaxis - now used less
● Blood products, red cells have O2 carrying capacity

24. Principles of Fluid Treatment
● Body Fluid = 42L = 28L IC + 14L EC = 28L IC + 3L plasma + 11L interstitial fluid
○ Plasma to interstitium = Starling forces, isotonic will automatically distribute (min)
○ EC to IC = osmotic forces, isotonic won’t cross membranes
○ 3/14L equals ~25%, so of any L of crystalloid only 250mL remain
intravascular
● Maintenance = deliver fluid and electrolyte requirements
○ 30-40mL/kg/d in adult
● Resuscitation = acute treatment of fluid loss
● Compensate for plasma loss
○ In Trauma, using saline, colloids or blood products
● Compensate for EC loss
○ E.g. in vomiting
○ Hartmann’s will replace interstitial fluid
● Compensate for water loss
○ 5% glucose (to make it isotonic), will distribute across EC and IC

25. Fluid Balance
● Body Fluid = 42L = 28L IC + 14L EC = 28L IC + 3L plasma + 11L interstitial fluid
● Routs of fluid loss: kidneys (urine, 1500-2000mL/d), GI (300mL/d), Insensible (skin
evaporation, resp. and other secretions ~700mL/d) ~ 3000mL loss
● Urine output = 0.5-1mL/kg/h
● Internal fluid recycling per day (gastric juices etc). ca 8L!
● Daily fluid loss ca. 1.5-2L (at rest), 3L normal, of which
○ 60mM K+ K+ requirements 1mM/kg/d or 70mM
○ 100mM Na+ Na+ requirements 1-2mM/kg/d or 150mM
● Maintenance = 30-40mL/kg/d
● Examples of maintaining fluid balance
○ 3L Dextrose/Saline = 40g Dextrose/30mM Na/20mM K+/1L bag
so gives 3L fluids, a total of 90mM Na+ and 60mM K+
○ 2L 5% Dextrose/20mM K+ and 1L 150mM (0.9%) Na+/20mM K+
gives 3L fluids, a total of 150mM Na+ and 60mM K+
● Adjust based on urine output and other losses

26. Post-operative Fluid Balance: General
● Increased steroid hormones and ADH cause Na+ retention, K+ excretion, water retention for 24-48h
● But K+ also released from damaged tissues, if kidneys hypoperfused then K+ may not be excreted =>
hyperkalaemia! => no supplementary K+ in first 48h post trauma or surgery.
● Rely on urine output, aim for >50mL/h (not <30mL/h)
●
● Losses: nasogastric aspirates, fistulae, diarrhoea, stomas
● Third space fluid losses
○ Transient ileus (leading to “third space fluid loss”)
■ Fluid secreted into bowel not recycled => extra fluids required (remember 8L of recycling
per day!)
■ Sudden diuresis on day 2-3 post surgery due to recovery from ileus
○ Pancreatitis
■ Fluid loss into peritoneal cavity
■ Vigorous monitoring of fluid output
○ Fistula, nasogastric tube, wound drain, stoma. Biochemical analysis may help characterise loss
● Calculate losses daily and replace with saline in addition to normal maintenance! Add K+ if
diarrhoea

27. Post-operative Fluid Balance: Specific
● Heart failure: on 1st post-up day 2L of fluid suffice
● Fever: increased fluid replacement by 10% for each degree of fever
● Heart failure, liver failure:
○ Avoid giving Na+, stick to 5% dextrose
○ Monitor fluid balance, JVP, watch for oedema (also pulmonary), CVP
○ Reduce or stop input and potentially start diuretics if overloaded
● Acute renal failure
○ Pre- and postrenal most common in relation to surgery
○ Renal cause: avoid K+, stop drugs that affect kidneys
○ Involve renal team
○ Assess patient’s hydration, U&Es and haematocrit, T

28. Fluid Resuscitation
● Clinical signs of dehydration (dryness, loss of skin turgor, postural
hypotension) suggest 5-15% fluid loss
● So in 80kg male 10% loss of 60% water is 4.8L. If loss from arterial blood
then can replace with Hartmann’s (isotonic)
● Rule: replace half of loss quickly and reassess before giving the rest
● E.g. by urine output returning to normal

29. Fluid Challenge
● 250-500mL saline bolus (colloids or blood if in shock)
● Observe urine output for 1h
● If increases => requires more fluid
● If SOB and increased JVP due to heart failure => call senior, central line
● Diuretics are rarely used to improve post-op urine output

30. Blood Transfusions
● 1 Unit (Hct 0.6 - normal 0.35) raises Hb by 10g/L

31. Nutritional Support
● May be necessary if patient malnourished prior to surgery
● Can give readily absorbable protein, fat and CH solution via fine bore
nasogastric tube alongside normal diet
● Consider feeding jejunoscopy at time of surgery if large nutritional deficit

32. Parenteral Nutrition
● Total parenteral nutrition (TPN) aims at covering complete nutritional requirements
● I.e. bypassing the gut, given per IV (central line, Hickman) into large central vein (high
osmolarity of solution)
● Contents: aa, CH(glu), fat emulsions and trace elements and vitamins
● 2.5L/24h with daily weighs and U&Es (electrolytes and albumin)
● Complications:
○ Hyperglycaemia (esp. post pancreatitis, may need insulin)
○ Increased risk of infection and sepsis
○ Electrolyte imbalances (monitor U&E daily and LFTs every few days)
○ Liver impairment, cholestasis
○ Villous atrophy
○ Thrombosis
● Temperature in patient with new TPN, may itself cause the fever, or infection of line
● Continue until positive nitrogen balance (patient may suddenly become more cheerful and
ask for food)

33. Post-Operative
Management

34. General Points
● Monitor recovery from anaesthetic
● Obs charts and fluid balance
● Follow instructions for specific post-op management by surgeon and
anaesthetist

35. Classification of Complications
● General vs specific
● Systemic vs local
● Immediate vs early vs late
● Consider contributive factors
○ Pre-operative vs operative vs postoperative

36. Overview of Complications
● General
○ Anaesthetic ANAESTHETIC PERIOPERATIVE COMPLICATIONS
■ Mouth, teeth trauma
■ Malignant hyperthermia
■ Hypothermia
○ Wound/Site of operation SURGICAL PERIOPERATIVE COMPLICATIONS
■ Haemorrhage
■ Infection
■ Deshiscence
○ Lack of mobility
■ Chest infection
■ DVT, PE
■ Bed sores
■ Transient ileus (electrolytes, opiates or mechanical handling of bowel)
○ Catheterisation
■ Urinary retention, UTI
● Specific
○ Immediate
■ Nerve damage
○ Long-term

37. Anaesthetic Complications
● Intubation: fractured teeth
● Obstructed airway from inhaled stomach contents, aspiration pneumonia
● Pulmonary collapse: occurs in first 48h
○ Accompanies almost any transthoracic or abdominal procedure. Process: mucus =>
air absorption => collapse => potential 2* infection => potential abscess formation.
○ Risk factors: pulmonary, smoking, anaesthetic drugs increase mucus secretion and
impair cilia, atropine increases the viscosity of mucous. POST OPERATIVE PAIN
also increases retained mucus
○ The collapsed bit of lung acts as a shunt => decreased oxygenation
○ Mx: breathing exercises (+/- small repeated doses of opiates to diminish pain on
coughing or even epidural or intercostal nerve blocks), Abx if infection, postpone
surgery if chest infection
● Bronchopneumonia
● Embolus
● TBC

38. Surgical: Haemorrhage
● Haemorrhage
○ 1* during the operation
○ Reactionary at the end of the operation when BP returns to normal
○ 2* after procedure, e.g. due to infection and erosion
○ Mx

39. Surgical: Wound Infections
● Wound infections - usually within the first week / few days after the operation
○ Depend on nature of surgery
■ Clean, clean contaminated (little spillage from viscus), contaminated,
dirty/infected
○ Depend on the location of the wound (skin commensals present)
○ Mx of minor infections
■ Replace dressings, potential Abx if cellulitis
○ Mx of more serious +/- cellulitis, significant discharge or abscess
■ Swab
■ Abx
■ Drainage of wound or abscess
■ Surgery

40. Surgical: Dehiscence
● Wound dehiscence - 1 week -10d post
○ Causes
■ Pre-operative: uraemia, cachexia, protein deficiency, malnutrition, Vit C
deficiency, jaundice, obesity, steroids
■ Operative/wound-related: poor technique in closing, obesity, infection,
haematoma, poor blood supply, pressure from coughing or distension
○ Signs:
■ Serosangiunous discharge followed by sudden burst = “pink fluid sign”
■ Actual bowel protruding through the wound
○ Mx:
■ Reassurance of patient + morphine and antiemetic
■ Cover with sterile soaked swabs followed by surgical repair
■ Resuturing under GA using nylon stitched through all layers of the abdo
wall and skin
■ High incidence of subsequent incisional hernia

41. Surgical: Fistula
● Causes: poor condition of patient, poor technique, poor blood supply,
sepsis, distal obstruction, malignancy, inflammation
● Effects: wound excoriation, loss of fluid and protein
● Ix
○ Methylene blue by mouth to confirm
○ Test fluid for bile, creatinine (=> urinary tract)
○ Contrastradiography to outline fistulous tract
● Mx
○ Protect surrounding skin (stromahesive / barrier creams), colostomy
bag or suction
○ Replace losses / IV feeding
○ Prevent infection/sepsis
○ If small may heal or subsequent surgery

42. General: Pyrexia
● >38*C
● Causes: mild = common normal reaction to operative stress and trauma
○ CHEST
○ CATHETER
○ CENTRAL VENOUS PRESSURE LINE
○ CANNULA
○ CUT = wound itself
○ COLLECTION = abscess, also internal deep abscesses such as subphrenic (4-10d) or
pelvic (7-21d)
○ CALVES = DVT, PE, start on heparin prior to Ix if suspected
● Mx
○ Examine patient: Chest, abdomen, cannula sites, wound
○ Ix - choose depending on Hx and Ex (rectal examination for pelvic abscess)
■ Blood: FBC, CRP, blood culture
■ CXR
■ Wound swabs
■ US, CT for suspected collections
■ ECG, CXR, ABG, leg US, ventilation-perfusion scan or CT pulmonary angiogram for
suspected DVT/PE

43. General: Oliguria
● Causes
○ Prerenal
■ Hypovolaemia, e.g. from haemorrhage
■ Heart failure
○ Renal
○ Postrenal = most common
■ Bladder outflow obstruction
■ Blocked catheter
■ Drugs
● Anaesthetic drugs affecting the bladder neck (anticholinergics)
● Opiates
● Epidural
■ Pain
■ Inhibition
● Mx
○ Hx, suprapubic pain?
○ Ex, hypovolaemia, heart failure, palpable distended bladder
○ Analgesia, privacy, relaxation, catheterisation or flushing of catheter, dipstick
○ Fluid balance charts, urine output, U&Es
○ Fluid challenge if prerenal cause suspected
○ U&E, creatinine, urine to plasma osmolality if renal cause suspected, contact renal team

44. General: Pseudomembranous Colitis
● C. diff infection after cephalosporin or co-amoxiclav Abx Rx (most
common), particularly after large-bowel surgery
● Complications: severe watery diarrhoea in cholera-like picture, toxic
dilatation, death
● Rx:
○ Fluid and electrolyte replacement
○ Stop broad-spectrum Abx => metronidazole or PO vancomycin
○ Isolation of patient and hygiene

45. General: DVT2nd week post surgery
● Note: post surgery platelets peak on day 10 and fibrinogen is raised. blood stagnates and there may be
inflammatory damage to venous wall completing Virchow’s triad.
● Investigations
○ Duplex scanning of lower limb and pelvic veins to determine filling defects
○ Venography (contrast X-ray)
○ 125I-labelled fibrinogen, unreliable in the pelvic and thigh region but shows beginnings of thrombi in ⅓
of post-operative patients
● Complications
○ PE day 10 post-op
■ Symptoms: Sudden onset or progressive dyspnoea, pleuritic chest pain, haemoptysis,
diaphragmatic irritation (shoulder pain), elderly: confusion due to hypoxia
■ Signs: Tachypnoea, tachycardia, raised JVP, calf tenderness, cyanosis, pleural rub
■ Ix: CXR (patchy shadowing), ECG (STdepr V1-V3, III, aVF and RAD or S1, Q3, T3), ABG, V/Q
scan (compare Krypton-81m gas distribution to Technetium-99m-albumin in blood), CTPA
■ Rx: opiate analgesia if pain, oxygen, heparin, streptokinase during CTPA unless recent surgery,
pulmonary embolectomy on bypass
○ Phlegmasia alba dolens
■ Complete occlusion of deep veins resulting in pain, swelling and whitening of the leg
○ Phlegmasia caerulea
■ Progression of the previous + occlusion of superficial veins + arterial flow

46. DVT - Risk Factors
● Vascular
○ Previous thrombosis
○ Thrombophilias, protein C, S, antithrombin III or factor Leiden mutations
○ Varicose veins with phlebitis
● Regarding surgery
○ Immobility
○ Abdominal , pelvic and hip operations!!! Lower limb amputations!
○ Operations longer than 90mins under anaesthetic
● Comorbidities
○ Cancer or cancer treatment
○ Critical care admission
○ Obesity of BMI >30
● Other
○ OCP (combined), HRT
○ Age >60
○ Dehydration

47. Complications of DVT
● PE
● Phlegmasia alba dolens
○ Complete occlusion of deep veins resulting in pain, swelling and
whitening of the leg
● Phlegmasia caerulea
○ Progression of the previous + occlusion of superficial veins + arterial
flow
○ Ischaemia and gangrene
● Venous gangrene

48. NICE Guidelines regarding DVT
● Relating to prophylaxis of hospital patients
● No prophylaxis if only local anaesthesia
● No prophylaxis if the risk of bleeding outweighs the risk of the DVT
○ Active bleeding
○ Acquired or untreated inherited bleeding disorders
○ Anticoagulants
○ LP/epidural/spinal anaesthesia carried out or anticipated
○ Acute stroke
○ Thrombocytopenia
○ Uncontrolled hypertension (>230 systolic)
● No prophylaxis if Vit K antagonists in therapeutic range
● No stockings if limb injury/incisions, heart failure, allergy, deformity

49. NICE Guidelines regarding DVT
● Base choice depending on DVT risk, risk of bleeding, clinical condition, patient
choice and nature of surgical procedure
● Available prophylactic tools
○ TED anti-embolism stockings
○ LMWHeparin injections (! in kidney failure)
○ Foot impulse device
○ Intermittent limb compression
○ Me: treatment of avoidable risk factors (e.g. stop OCP 6w prior), active
mobilisation
● Note: not from the guideline, if a patient has continuous PEs despite adequate
anticoagulation, consider insertion of IVC filter.