The post-operative patient needs management of various issues including pain, delirium, respiratory compromise, cardiovascular issues, and infection. Major post-op issues stem from the body's stress response to surgery, including systemic inflammation, catabolism, insulin resistance, and fluid/electrolyte changes. Care requires monitoring for signs of organ dysfunction and providing support for individual organ systems while addressing surgery-specific concerns.

1. The post-operative patient
Arun Radhakrishnan

2. Applied physiology
 Needs good understanding of whole body
physiology as well
 Not limited to one organ system!!!
 What would be the major issues in such a
patient?

3. Major post-op issues
Pain
Delirium
Anaesthesia-related
Surgery-specific
Respiratory compromise
Cardiovascular issues
Fluid-electrolyte-metabolic
Ileus
Infection
State of inflammation/SIRS

4. Stress response to surgery

5. Systemic response to surgery
Secretion of pituitary hormones plus activation of
the sympathetic nervous system
Catabolism
Breakdown of skeletal muscle and fat
Insulin resistance and hyperglycaemia
Retention of salt and water

6. Systemic response to surgery

7. Systemic response to surgery
SIRS (Systemic inflammatory response
syndrome) (at least 2 of the following criteria):
Temperature > 38 0C or < 36 0C
HR > 90
RR > 20
WBC count < 4 or > 10 or > 10% immature neutrophils
SIRS may lead to organ injury or failure, often
multiple

8. Haemodynamic response
Hypovolemia due to blood loss or fluid loss
Post-op fluid and water retention, independent of
intraoperative loss
ADH
Aldosterone
Immune response: Increased Cytokine release,
complement activation- may lead to SIRS
Impaired (exhausted) response may predispose to
infections

9. Effects of anaesthetics
Opioids
Respiratory depression
Suppress hypothalamic and pituitary hormone release esp. ACTH
Suppress the hyperglycaemic response
Non-osmotic release of ADH (SIADH)
Decrease bowel motility - ileus
Benzodiazepines
Inhibit cortisol production
Etomidate
Suppresses cortisol and aldosterone production – increases mortality
Clonidine - Inhibits stress response

10. Regional anaesthesia
Epidural or paravertebral blocks
Blocks both pain and efferent autonomic output in pelvic and LL
surgeries, less effective for thoracic and upper abdominal
surgeries
Can cause urinary retention (esp. intrathecal morphine)

11. Case
 Mr X, 39/M post-op in Critical care (Previously
well)
 Emergency laparotomy for peritonitis
 Previous urgent laparotomy 1 week ago for
diverticular perforation
 Pre-op: GCS 14, HR 112, BP 90/58 mm Hg,
SpO2 on room air 89%, Urine output 15-25
mL/hr

12. Post-operative physiology
 Impact of derangements depend on:
 Type of surgery – Elective Vs Emergency
 General health pre-op
 Co-morbidities
 Organ dysfunction(s) present (acute and chronic)
 Duration of surgery
 Anaesthetic management
 Post-anaesthetic care

13. Surgery-specific
 Operative site- e.g.; H&N or airway surgery,
abdominal surgery etc.
 Bleeding or discharge from drains or wound(s)
 'Health' of the stoma

14. General Considerations
 Pain management
 PONV
 Temperature management
 Fluid management- volume status determination
 Organ system support- Respiratory and Cardiovascular, Renal
 Nutritional considerations
 Preventing complications of immobility
 Housekeeping

15. Pre-existing conditions
 May require specific management eg; CCF,
COPD, CKD
 May need careful balancing of goals eg: Fluid
management in the patient with CCF

16. Organ systems
 Neurologic
 Level of consciousness
 Cardiovascular
 CR (if not hypothermic)
 Respiratory
 Rate, FiO2, Pattern, SpO2
 Renal
 Urine output- accept a total output of > 500
mL over 24 hrs

17. Organ Systems
 Metabolic
 pH, pCO2, HCO3, Lactate, BSL
 Think about the cause for derangements!

18. Pain
 What is the problem with pain?
 Complex entity made up of sensory, affective,
motivational and cognitive dimensions
 Unpleasant for the patient
 Sympathetic responses- HR, BP, increased O2
demand
 Site-specific: Respiratory compromise
 Inability to mobilise/physio

19. Pain
 Neuroendocrine effects- the SIADH
 Non-osmotic signal to retain fluid
 Manifest as post-op Hyponatremia and/or oliguria
despite clinically normal cardiac output and volume
status

20. Pain management
 Prevention is better than cure
 Multimodal analgesia
 IV, Regional and Local techniques
 Side-effect profile very important, eg;
respiratory depression with opioids

21. Temperature
 Why is 'normal' temperature important?
 Causes of hypothermia in post-op patients?
 Problems with hypothermia:
 Shivering
 Metabolic acidosis
 Cardiovascular issues- arrhythmias, increased O2
demand, cardiovascular depression etc.
 ↓ drug metabolism, ↓ platelet function, drowsiness

22. Cardiovascular issues
• Low BP
• HTN
• Arrhythmias
• Cardiac ischaemia
• More common with pre-existing cardiac or
respiratory dysfunction

23. Cardiovascular issues
 Cardiovascular 'signs' of low volume status
 How reliable is BP as an index of volume in the
post-op period?
 What is the most important cause of HTN in this
scenario?
 Pain
 Anxiety, drug withdrawal, urinary retention
 What are the causes of Hypotension?

24. Causes of hypotension
 Intravascular volume depletion
 Ongoing losses eg; haemorrhage
 Sepsis
 Myocardial dysfunction (Peri-operative MI)
 SIRS response- capillary-leak
 Regional blocks
 Usual causes of shock!!!

25. Management of Hypotension
 Determine the Volume status
 We have been struggling for over 50 yrs to do so!!!!
 History and physical examination essential
 Previous or ongoing fluid losses and intake (I/O charts)
 3rd space losses?
 Sluggish CR
 Postural hypotension
 Persistently poor urine output
 Signs of heart failure
Patients for elective surgery are unlikely to be ‘fluid-deficient’ peri-operatively

26. Options to manage Hypotension
 What are we trying to achieve????
 'Normal' perfusion- a cardiac output that is
'sufficient' to meet body needs without incurring
the risk of complications
 CO = Stroke volume x HR
 Stroke volume depends on Preload, Afterload
and Contractility
 HR and rhythm important

27. Options to manage Hypotension
 How important is it to 'normalize' the patient's
vitals?
 Is the 'low' BP compromising the patient, or is it
likely to compromise him/her?
 Options- optimise preload (CVP or JVP gives a
rough idea- please do not chase numbers)
 Avoid medications that could compromise
contractility eg; anti-hypertensives, anti-CCF

28. Role of the 'Fluid Bolus'
 Estimation of the volume status extremely
difficult, even in intensive care
 Estimate pre- and intra-op fluid losses and
replacement
 Duration of pre-op pathology
 Intake pre-op
 Anaesthetic charts for intra-op Mx
 Normal fluid requirements 30 mL/kg/day

29. Role of the 'Fluid Bolus'
 Patient warm, CR < 2
s, no organ system
derangement obvious
 SBP 96, MAP 65
 U/O 20 mL in last
hour
 Does this patient
need a fluid bolus?

30. Fluid bolus
Ensure fluid bolus is targeted at physiologic need, rather
than to (ad)dress numbers!!!!
Low volumes of fluid (250 mL or 500 mL)- constantly re-
assess for response before going on to next bolus
Have a ‘stop’ limit in your mind!
Keep the clinical situation in mind-are we actually dealing
with a low CO?
Is tissue perfusion adequate?
Is the patient bleeding?

31. Complications of fluid overload
Pulmonary congestion
APO
Pleural effusions
Hypoxia
Worsen heart failure
Worsen bowel perfusion and impair anastomotic healing
Ascites
Worsen renal perfusion
Hyperchloremic metabolic acidosis
Dilutional throbocytopenia

32. Hypotension-vasoactive agents
Leaky capillaries due to SIRS
Myocardial dysfunction
Problems with excessive fluid ‘resusc’
Choice of agent depends on principal reason for
hypotension: Cardiac dysfunction (Inotropic
agents) Vs. Vasoplegia (Vasopressors)

33. Arrhythmias
Common after thoracic surgery
Electrolyte disorders (K, Mg, Phosphate)
predispose

34. Hypoxia
 SpO2 < 90% on room air (Aim > 90-92%)
 What are the important causes of hypoxia?
 Is PaO2 more important than the SpO2?
• Pain causing respiratory compromise-hypoventilation,
impaired sputum clearance
• Fluid overload
• Collapse (Atelectasis)
• Consolidation
• Aspiration
• PE
• Surgery-specific – Pneumothorax post-thoracic surgery or
post-CVC insertion

35. Management of Hypoxia
 O2 Supplementation
 Improve V/Q mismatch
 SOOB, Physiotherapy
 Diuresis
 Positioning
 Specific cause –e.g. Antibiotics

36. Mx of Hypoxia
 Mechanical ventilation or Non-invasive
Ventilation if:
 ↑ WOB
 SpO2 < 90% on high FiO2 (> 0.5)
 Progressive or severe respiratory acidosis, or
inability to compensate for metabolic acidosis
 Severe Pain causing impairment of respiration or of
cough

37. Volume status and renal function
Post-op tendency to fluid retention due to SIADH (non-osmotic
release of ADH)
Sympathetic response contributory
Hyponatremia very common
'Leaky' capillaries- loss of intravascular fluid into interstitial spaces
Urine output decreases not a reliable sign of hypovolemia
Do not administer fluid boluses to improve urine output if CO
clinically adequate!!!

38. Oliguria
Pre-existing cardiovasc or renal issues
Causes:
Intravascular volume depletion
Hypotension
Low Cardiac output
Nephrotoxic agents-IV contrast
Direct injury to ureters
Obstruction at level of bladder (? blocked IDC)
Heard of the abdominal compartment syndrome???

39. Renal Function
Anuria always a cause for concern
Most common causes for kidney compromise are- hypotension
and hypoxia
Intravascular volume depletion
Excessive use of chloride-rich IV fluids (NS, Gelofusine)
Suspect surgical issues- eg: have the ureters been ligated (Pelvic
surgery)- very rare cause
Mild rhabdomyolysis due to prolonged positioning intra-op
Generally, re-establishing adequate perfusion and avoiding
nephrotoxic agents resolves the issue.
Dialysis may be needed for usual indications

40. Don't forget the gut!!!
Bowel dysmotility- paralytic ileus
Type of surgery
Opioids
Nutritional issues

41. Refeeding syndrome
Severe hypophosphatemia (respiratory- and
cardiac failure, shock, rhabdomyolysis, seizures
and delirium) due to insulin release after period
of fasting. Associated with hypokalemia and
hypomagnesemia.
Malnourished patients, alcoholics, ongoing
electrolyte losses are predisposed
Monitoring is critical

42. Glucose control
Insulin resistance and catabolic state with surge of
counter-regulatory hormones
Very important to maintain euglycaemia (BSL 7-
10) esp after major surgery
Adverse effects of Hyperglycaemia: Wound
infection, osmotic diuresis, dyselectrolytemias

43. Anaemia and blood loss
Causes:
• Surgical bleed
• 'Dilutional'
• Pre-existing anaemia
Contribution of coagulopathy
Why are we concerned?????

44. 'Management' of anaemia
Correct the cause- surgical bleed to be corrected (surgical Vs. radiologic Vs.
Endoscopic)
Correct coagulopathy- what are the post-op factors that can worsen
coagulopathy???
Considerations: Site, amount, and haemodynamic significance, and patient's
tolerance
We are trying to improve/maintain oxygen delivery
RBC transfusions usually not required
Role of prophylactic PPI to prevent stress ulceration

45. Thromboembolism
Surgery and anaesthesia foster a hypercoaguable
state
High risk of DVT post-op
Methods to protect and prevent
Sometimes problematic if concurrent bleeding
issues

46. Infection and sepsis
Patient background- immunocompromised?
Nature of surgery

47. Post-op Fever
Does fever always mean an infection???
What are the non-infectious causes of fever?
DVT/PE
Indwelling devices e.g. CVC
Medications (drug fever) or Drug withdrawal
Stroke or intracranial bleed
Seizures
SIRS
Transfusion reactions

48. Delirium
• Very common
• Causes:
• Predisposing factors (age, dementia, sensory deprivation)
• Pain
• Direct neurologic insult
• Organ dysfunction
• Sepsis (think surgical sepsis)
• Drugs eg; opiates
• Urinary retention (esp. with neuraxial blocks)
• Never forget hypoxia, hypercarbia or low BSLs

49. Delirium treatment
Prevention always best
Early recognition
Re-orientation and reassurance
Family presence
Nocte antipsychotics
Chemical – haloperidol, olanzapine etc.

50. Metabolic issues
• Metabolic acidosis very common
• Hypothermia and peripheral vasoconstriction
• Hyperchloremic acidosis
• Accentuated by lack of ability to self-correct in
an anaesthetised patient
• Concern if reflects persistent low cardiac output
state (Raised lactate)

51. Site-specific problems
Thoracic surgery
Pain with respiratory
impairment
Pneumothorax
Haemorrhage
Abdominal surgery
Pain with respiratory
impairment
Post-op ileus
Abdominal compartment
syndrome
Bleeding

52. Patient-specific problems
Cardiac disease
Compromised cardiac
output
Fluid and electrolyte
derangements
Sepsis
Peri-op MI
Respiratory disease
May be worsened by
surgery
Hypoxia may worsen
outcomes

53. Warning signs
What are the danger signs of organ
dysfunction???
Trends are more important than single 'snapshot'
values
Exceptions are- airway obstruction, ↓LOC, Shock,
Severe hypoxia or cyanosis, respiratory distress
or anuria

54. Summary
State of inflammation
Pain and organ dysfunction
Needs comprehensive management