Perioperative Mx & Post Op Complications Flashcards
What is the approximate composition of a 70kg male?
- Fat (15kg)
- Protein (12kg)
- Water (42kg)
- Glycogen and minerals (1kg)
How is total body water divided?
2 main compartments:
- extracellular fluid 19L
- intracellular (cytoplasmic) 23L
How is the ECF divided?
-Interstitial - 15L
-Intravascular (plasma) - 3L
-Third space (GIT/Renal) - ~1L
(may change if normal transcapillary exchange is interfered with e.g. inflammation).
What is the post-op hormonal response and its effect?
24-48h post op have increased cortisol, aldosterone and ADH secretion:
- decreased renal Na excretion (therefore decreased water excretion to maintain osmolality)
- increased renal K+ excretion (some results from tissue damage and breakdown of cells)
- decreased renal water excretion (sml vol, high {} urine), independent of intake.
What are the aims of post op water and electrolyte therapy?
- Maintenance needs
- Replacement of pre-existing deficits
- Replacement of ongoing losses
What are the maintenance requirements in 70kg male?
Water: 100mL/h (increased for fever)
Na: 75mmol/day
K+: 60mmol/day
What are the common sites of ongoing post op fluid loss?
- GIT: NGT aspirate or vomit, fistula, diarrhoea
- Third spacing: inflammation e.g. retroperitoneal effusion in pancreatitis
How should ongoing fluid loss be assessed?
Recording of fluid balance, daily weights if possible.
How should measured upper GIT losses be replaced?
Isotonic sodium containing solutions (0.9% saline or Ringer’s lactate) supplemented with potassium.
How should third space losses be replaced?
Not directly assessable. Replace with Ringer’s lactate solution.
Volume determined through clinical assessment of fluid balance.
How are post op energy requirements determined?
- Body weight (fat free mass)
- Degree of surgical trauma
- Sepsis
- Nutritional status
What is the energy requirement per kg body weight?
40cal/kg/day
Should be based on fat free mass (i.e. care not to overprescribe in obese or oedematous).
Factors contributing to poor post op respiratory function?
- Preop res disease
- Anaesthesia (PPV + Rx ==> may cause V/Q mismatch)
- High FiO2 to correct low SaO2 ==>patchy collapse of alveoli due to decreased N content
- Hypoventilation: pain, supine, decreased cough reflex, anaesthesia/analgesia.
What happens to the post op WCC?
Normally slightly increased for 2-3d post op; marked elevation during this period or prolonged elevation indicates infective/inflammatory process.
Routine post-op investigations?
- BSL (diabetics)
- Hb (24-36h post op)
- WCC (if ?sepsis)
- UEC (when fluids required)
- ABGs (if ?resp insufficiency)
What are the effects of post op pain?
- Decreased respiration (>hypoventilation/collapse)
- GIT atony (ileus/N/V)
- Bladder atony (retention)
- Catecholamine release (vasoconstriction, increased blood viscosity, active clotting).
How are surgical wounds classified?
- Clean
- Clean-contaminated
- Contaminated
- Dirty
What are the forms of peri-operative haemorrhage?
- Primary: occurring during op
- Reactionary: at conclusion of op with restoration of CO and BP –> dry wounds bleed
- Secondary: days after op
How can post op haemorrhage be identified?
- Overt bleeding
- Peripheral shutdown (mottling),
- hypovolaemia (hypotension/ tachycardia/ tachypnoea/ decreased urine output.
- Distension after abdo surgery
Causes of post op circulatory collapse?
- Haemorrhage
- Severe sepsis
- MI
- PE
- Hypersensitivity reaction
Mx of post op haemorrhage?
- Stop source (may need re-op)
- Correct coagulopathy
- Assess for transfusion need
What are the clinical features of sepsis?
- High pyrexia
- Tachycardia
- Hypotension
- Warm periphery
What are the factors contributing to post op pulmonary complications?
- Wound pain (esp upper abdo/chest)
- Limitation of resp excursion
- Ciliary paralysis
- Drying of bronchial secretions
- Oversedation
- Obesity
What are the types of wound dehiscence?
- Superficial and revealed (2/52 when sutures removed; skin and subcutaneous tissues separate; wound haematoma or cellulitis)
- Deep and concealed (any time post op; all layers of abdo except skin separate = incisional hernia)
- Complete and revealed (10/7 post op with protrusion of abdo contents).
Mx insulin in IDDM patients?
IV dextrose infusion and 0.5 normal insulin dose given morning of op.
Glucose throughout op guided by repeated BSL monitoring.
5Ws of post op fever?
- Wind: POD #1-2 (pulmonary atelectasis, pneumonia)
- Water: POD #3-7 (urine - UTI)
- Wound: POD #3-7
- Walk: POD #8 (DVT/PE)
- Wonder drugs: POD #1+ (drug fever)
Post op fever hours after surgery?
- Inflammatory response to surgical trauma
- Reaction to blood products received during surgery
- Malignant hyperthermia
Causes of POD#1 fever?
Acute:
-Atelectasis (most common!)
-Early wound infxn (esp Clostridium, GRPA Strep)
-Aspiration pneumonitis
Other: Addisonian crisis, Thyroid storm, transfusion rxn.
Important Hx features in post op ward round?
- Op and context in which it was performed
- Is the pt feeling well?
- Is the nutritional and fluid intake adequate?
- Is there return or normal body function?
- Is the analgesia adequate?
Exam features in post op ward round?
- Vital signs
- Fluid balance
- Output for drains / ?remove
- Operative sites
Ward round considerations re medications.
- VTE prophylaxis
- ?Cease: ABx, analgesics
- Other: ?analgesia, aperients, antiemetics, regular Rx
Urine output to be maintained =?
> 30mL/hr or >1/2mL/kg/hr
FLuid balance considerations D1 and D2 post op?
D1: increased ADH, do not give excessive fluids
D2: mobilisation often shifts fluid from interstitium back into intravascular space (decreased IVF in anticipation)
Mx of low urine output?
- If anuria, check for blocked IDC
- Assess pt for hypovolemia
- Ensure pt not bleeding
- Give fluid challenge (500-1000mL stat crystalloid)
Considerations in preventing post op complications?
- Mobilisation: aim D2
- Chest physio
- VTE prophylaxis: mechanical and chemical
- Adequate analgesia
- Adequate nutrition and fluids
Mx surgical wound infection?
- ? open suture line
- Drain underlying abscess
- Swab for MCS
- Heal by secondary intent
- ABx
When may superficial wound dehiscence occur?
- If wound poorly apposed
- Suture /staples cut through
What is deep wound dehiscence?
Burst abdomen due to dehiscence of fascial layer (sutures pulled through, slipped knot, poor tension).
How does deep wound dehiscence appear on inspection?
Excessive haemoserous discharge from suture line or bowel on view.
Mx deep wound dehiscenc?
Usually return to theatre; consider tension sutures.
RFx for incisional hernia?
Poor wound healing, RFx:
- poor nutrition
- obesity
- smoking
- steroids
- DM
- ureamia
- jaundice
- infection
- malignancy
- tissue ischaemia
How can surgical drains be classified?
Tubed v corrugated
Active v non-active
Purpose of surgical drains?
- Prevent collections from accumulating
- Detect underlying complications
- May be used to create controlled fistula
Common drains?
Suction: Jackson Pratt, Redivac
Non suction: Penrose, Yate’s
What is a T tube used for?
-After bile duct exploration
When can T tube be removed?
Never before T tube cholangiogram (1/52)
What is the role of an external ventricular drain?
-Relieves hydrocephalus
-Can check CSF pressure
Be very careful with it!!
60y male D2 post total gastrectomy. UO 300mL in last 12h.
Input: 2L IV
Output: 1900mL various sources.
Management?
- Check IDC
- Fluid balance assessment
- Ensure not bleeding
- Give fluid! N Sal 1L over 2/24. Next bag over 4/24.
- Review
50yo male D4 post incisional hernia repair with finding of SBO. Now vomiting ++.
Possible causes?
- Post op ileum
- SBO
- Ischaemic / infarcted SB
- Gastric dilation
- Drugs (narcotics)
50yo male D4 post incisional hernia repair with finding of SBO. Now vomiting ++.
Management?
- Antiemetics (maxolon, stemetil, ondansetron)
- Place NGT: free drainage and aspirate
- Give IVF (check fluid balance)
- Order AXR (S & E)
80y woman D2 post open cholecystectomy. Confused.
Possible causes?
- Hypoxia: atelctasis, chest infection, over sedation, CCF, MI, PE
- Sepsis: chest / urine / wound / intraabdo (bile leak)
- Rx: opiates, sedatives
- DTs
- Metabolic: uraemia, hyponatremia, hypo-/-erglycemia
Mx of post of confusion?
- Hx (staff or family)
- Turn on lights
- Check Hx for pre op state, EtOH, drugs, diabetes
- Check obs
- Examine pt
- Give O2
- Ix: ABG, RBG, UEC, FBE, Blood cultures, MSU, CXR, ECG
78y man 6h post abdominoperineal resection; lost 2L blood in theatre ==> 2xPRBC + 1500mL gelofusine. Epidural infusion in situ.
BP now 85/50.
What may be causing hTN?
- Hypovolemia: bowel prep and fasted, long op, behind in fluid replacement, 3rd space loss, sepsis
- Epidural causing peripheral vasodilation
- MI or CCF
78y man 6h post abdominoperineal resection; lost 2L blood in theatre ==> 2xPRBC + 1500mL gelofusine. Epidural infusion in situ.
BP now 85/50.
Mx?
-Decrease rate or cease epidural infusion
-Check FBE, UEC, ECG
-Give IVF +/- blood
(start N Sal 1L over 30min, R/V; may need gelofusine stat 500L if no response).
-If G-ve sepsis possible, give IVABx (3rd gen cep or stat gentamicin)
What is a PICC line?
- Inserted by radiology under U/S into basilic vein in upper arm
- Use for TPN / other infusions
- Risk of venous thrombosis of basilic vein
- Can be used for weeks
How is CVC inserted?
Into IJV or subclavian vein with tip in SVC.
Usually in theatre or recovery.
How long can CVC remain in situ?
5-21d (ABx impregnated)
CVC risks?
- IMMEDIATE: Pneumothorax, arterial puncture, haematoma
- LATE: thrombosis, stenosis, sepsis
What is vascath?
Temporary catheter used for haemodialysis. Inserted into IJV or femoral vein. NOT SUBCLAVIAN
What is a permcath?
-Long term catheter for dialysis with dual lumen
Where is permcath placed?
Placed in IJV or EJV
Risks with permcath?
Infection and blockage
What is the type / function of catheters used for chemotherapy?
Infusaport / Portocath
Buried port on chest wall with line into SVC. Placed under GA; used for long term central access for chemotherapy, IVD, blood taking.
-Less risk of infection
What is the purpose of Hickman catheter?
Single or dual lumen catheter; tunnelled with cuff to prevent infection.
Used for chemotherapy, bone marrow infusion, blood transfusions, long term TPN.
How should cuffed line be removed?
- Use local anaesthetics
- Cut down over cuff
- Excise with line
- Suture
