Cytokines in Health and Disease

What Are Cytokines?

Classification of Cytokines

• TNF/TNFR superfamily: TNF, lymphotoxins, CD40L (B/T cell activation), FasL (apoptosis)
• IL-1/IL-1R superfamily: IL-1α, IL-1β, IL-18, IL-33, IL-36; plus IL-1RA (receptor antagonist) and Toll-like receptors (TLRs) - pattern recognition molecules for microbial products
• Common gamma-chain family: IL-2, IL-4, IL-7, IL-9, IL-15, IL-21 - all share the γc receptor subunit
• IL-6/gp130 family: IL-6, IL-11, IL-27, oncostatin M - share the gp130 signaling chain

Cytokine Receptors

Cytokine Signaling

1. Cytokine binds receptor, inducing dimerization
2. Receptor-associated JAK (Janus kinase) is activated and auto-phosphorylates
3. JAK phosphorylates STAT (Signal Transducer and Activator of Transcription) proteins
4. Phosphorylated STATs dimerize and translocate to the nucleus to drive gene transcription
5. mRNA is translated to effector proteins, which are secreted or expressed on the cell membrane
6. microRNAs provide post-transcriptional regulation, dampening the response

Cytokines in Health

1. Innate Immune Defense

• IL-1, IL-6, TNF-alpha: Fever, acute phase response, neutrophil and monocyte recruitment
• IL-12, IL-18: Drive NK cell and later Th1 CD4+ T cell responses
• Type I interferons (IFN-alpha/beta): Antiviral; induce an antiviral state in neighboring cells, activate NK cells, upregulate MHC class I

"Viral infection can induce the release of cytokines (e.g., TNF, IL-1) and type 1 and 3 interferon from infected cells, macrophages, and especially plasmacytoid DCs." - Medical Microbiology 9e

2. Adaptive Immunity

• IL-2: T cell proliferation and survival (the quintessential T cell growth factor)
• IL-4, IL-13: B cell class switching to IgE; Th2 polarization
• IFN-gamma: Activates macrophages for killing intracellular pathogens; Th1 polarization; upregulates MHC II
• IL-10: Anti-inflammatory; suppresses pro-inflammatory cytokine production; produced by regulatory T cells (Tregs) and Th2 cells
• TGF-beta: Suppresses immune activation; promotes Treg differentiation; tissue repair

3. Hematopoiesis

• G-CSF: Neutrophil production (clinical use: post-chemotherapy neutropenia)
• GM-CSF: Granulocyte and macrophage production
• IL-3: Multi-lineage progenitor growth
• IL-5: Eosinophil production and activation; anti-IL-5 (mepolizumab) reduces eosinophils in severe asthma

4. Tissue Repair

• TGF-beta, PDGF: Fibroblast activation, wound healing
• VEGF: Angiogenesis
• IL-10: Limits excessive inflammation to prevent tissue damage

Cytokines in Disease

Rheumatoid Arthritis (RA)

• TNF-alpha and IL-1beta: Drive synoviocyte proliferation, cartilage destruction (matrix metalloproteinases), osteoclast activation (bone erosion)
• IL-6: Drives acute phase response (CRP, SAA, fibrinogen); serum levels correlate with disease activity in RA, juvenile arthritis, ankylosing spondylitis, and polymyalgia rheumatica; more sensitive than ESR for detecting activity in giant cell arteritis
• IL-17: Tissue inflammation, neutrophil recruitment
• IL-15: Promotes T cell activation; downregulated by methotrexate

Psoriasis and Psoriatic Arthritis (PsA)

• Psoriatic plaques and synovium show elevated IL-17A, IL-17F, IL-22, and TNF-alpha
• IL-23 drives Th17 differentiation; IL-17 promotes keratinocyte proliferation and neutrophil recruitment
• Genetic polymorphisms in IL-12 and IL-23 are associated with susceptibility to psoriasis and PsA
• Blocking the shared IL-12/IL-23 p40 subunit (ustekinumab) improves both skin and joint disease; blocking p19 (IL-23 only, e.g., guselkumab) achieves near-complete skin clearance

Allergic Disease and Asthma

• IL-4: Drives B cell class switching to IgE; upregulates VCAM-1 for eosinophil recruitment
• IL-5: Eosinophil production; anti-IL-5 (mepolizumab) reduces asthma exacerbations
• IL-13: Airway hyperresponsiveness, mucus production
• IL-9: Mast cell proliferation
• Mast cells, when activated, release TNF, IL-1, IL-4, IL-5, IL-6, IL-9, IL-13, CCL3, and CCL4 - fueling the allergic late-phase reaction

Sepsis and Cytokine Storm

• TNF, IL-1, IL-6, IL-8, IL-12, IFN-gamma - rapid systemic release causes fever, vasodilation, capillary leak, coagulopathy
• Can progress to septic shock, multi-organ failure
• Superantigen-mediated cytokine storm (e.g., Staphylococcal toxic shock syndrome toxin): activates 20-30% of all T cells simultaneously, generating enormous TNF and IL-2 release
• Viral cytokine storm: Seen in highly virulent influenza (H5N1, H1N1), dengue haemorrhagic fever, and COVID-19 - characterised by elevated IL-6, IL-1beta, IL-18, TNF, IFN-gamma

Cancer

• IFN-alpha: Anti-tumor (used in hairy cell leukemia, melanoma)
• IL-2: T cell expansion; high-dose IL-2 used in metastatic melanoma and renal carcinoma
• TNF: Can induce tumor cell apoptosis but chronic low-level TNF promotes NF-kB-driven tumor survival and angiogenesis
• IL-6: Promotes survival of myeloma cells; tocilizumab is used for cytokine release syndrome (CRS) post-CAR-T therapy
• TGF-beta: Profoundly immunosuppressive in the tumor microenvironment; inhibits T cell killing

Inflammatory Bowel Disease (IBD)

• TNF-alpha: Central in both Crohn's disease and ulcerative colitis; anti-TNF agents (infliximab, adalimumab) are mainstay therapy
• IL-23/IL-17 axis: Genetic studies show IL-23R variants associate with Crohn's disease
• IL-10: Deficiency leads to spontaneous colitis in mouse models; mutations cause early-onset IBD in infants

Neurological Disease

• IL-6, TNF, IL-1beta: Elevated in CSF and serum during neuroinflammatory conditions (MS, encephalitis)
• Type I interferons: Central to MS pathogenesis and also to treatment (IFN-beta reduces relapse rate in relapsing-remitting MS)

Cytokine Measurement in Clinical Practice

• ELISA and multiplex assays (measure 25-360 cytokines in ~20 µL sample simultaneously)
• Quantitative PCR / TaqMan arrays at the mRNA level
• Single-cell sequencing to identify cytokine sources in complex tissue biopsies

Cytokine-Targeted Therapeutics

Summary Table of Key Cytokines

• Firestein & Kelley's Textbook of Rheumatology - Classification, receptors, signaling, regulation, RA, PsA
• Cellular and Molecular Immunology - Allergic disease, mast cells, eosinophils
• Medical Microbiology 9e - Cytokine storm, antiviral responses
• Goodman & Gilman's The Pharmacological Basis of Therapeutics - Innate/adaptive immunity overview
• Henry's Clinical Diagnosis and Management by Laboratory Methods - Cytokine measurement

What's inside (4 slides)

• RA / JIA: csDMARD (MTX) → Anti-TNF → Tocilizumab (IL-6R) → JAK inhibitors → Anakinra/Canakinumab (Still's)
• PsA / AS: IL-17A inhibitors vs. anti-TNF based on skin vs. axial dominance; IL-23 inhibitors for PsA
• SLE: Anifrolumab (anti-IFNαR) / Belimumab / Baricitinib
• GCA / PMR: Tocilizumab + steroid taper
• Pre-biologic screening checklist (TB, HBV, pregnancy, heart failure warning)

• IBD: Vedolizumab, Ustekinumab, Risankizumab, JAK inhibitors, Anti-TNF
• Severe asthma: Eosinophilic → Anti-IL-5 (Mepolizumab/Benralizumab) / Dupilumab; Tezepelumab (any phenotype)
• Atopic dermatitis/urticaria: Dupilumab, Tralokinumab, Omalizumab
• CAR-T CRS: Tocilizumab (grade ≥2), Siltuximab if refractory
• Checkpoint inhibitor irAEs: Steroids, Infliximab (colitis), Tocilizumab (myocarditis)
• MAS/HLH: Anakinra → Tocilizumab → Emapalumab
• Severe COVID-19: Baricitinib (WHO strong recommendation), Tocilizumab, Dexamethasone

Cytokines in Systemic Diseases

1. The Acute-Phase Response: The Prototypic Systemic Cytokine Effect

"Endogenous pyrogens cause fever by inducing the synthesis of prostaglandin E2 by the enzyme cyclooxygenase-2... Prostaglandin E2 then acts on the hypothalamus, resulting in an increase in both heat production from the catabolism of brown fat and heat retention from vasoconstriction." - Janeway's Immunobiology 10e

• C-reactive protein (CRP): Binds phosphocholine on bacterial/fungal surfaces - acts as opsonin and activates classical complement. Rises faster than ESR; most clinically used inflammatory marker
• Serum amyloid A (SAA): Can accumulate in tissues in chronic disease causing secondary AA amyloidosis
• Fibrinogen: Elevated ESR; coagulation; contributes to hypercoagulability in inflammatory states
• Mannose-binding lectin (MBL): Activates lectin complement pathway; pattern recognition

2. Sepsis and SIRS: Cytokines Turned Lethal

Mechanism

1. IL-1beta and TNF-alpha cause neutrophil adhesion to endothelium at sites remote from infection
2. Activated neutrophils release reactive oxygen species (ROS), lysosomal enzymes, and free radicals
3. This damages distant organ endothelium, increasing vascular permeability
4. Coagulation, complement, and fibrinolytic pathways activate simultaneously
5. Result: Multi-Organ Dysfunction Syndrome (MODS) → Multiple System Organ Failure (MSOF)

"Septic manifestations and MODS in SIRS are mediated by the release of pro-inflammatory cytokines such as IL-1 and TNF-alpha. These cytokines... stimulate neutrophil adhesion to endothelial surfaces adjacent to the source of infection... The activated neutrophils adhere to vascular endothelium in key organs remote from the source of infection and damage it, leading to increased vascular permeability... which in turn leads to cellular damage within the organs." - Bailey & Love's Surgery

The Sepsis Cytokine Cascade

• Lungs: IL-8-mediated neutrophil recruitment → ARDS
• Kidneys: Macrophage ROS + pro-inflammatory cytokines → acute tubular necrosis
• Liver: TNF-driven hepatocyte apoptosis; cholestasis
• Brain: Sepsis-associated encephalopathy - occurs in the majority of patients with sepsis and MODS
• Heart: TNF-alpha directly depresses myocardial contractility (negative inotrope)

3. Autoimmune Systemic Diseases

Systemic Lupus Erythematosus (SLE)

• Plasmacytoid dendritic cells (pDCs) produce enormous quantities of IFN-alpha in response to nucleic acid-containing immune complexes
• IFN-alpha activates DCs, promotes autoreactive B and T cells, enhances autoantibody production
• The "interferon signature" (elevated IFN-stimulated gene expression) is detectable in >75% of SLE patients
• Complement deficiency/excess activation triggers IFN production, perpetuating a vicious cycle

• IL-6: Drives B cell differentiation into antibody-secreting plasma cells; elevated in active SLE; levels correlate with anti-dsDNA titres
• BLyS/BAFF: B lymphocyte survival factor - massively overproduced; promotes autoreactive B cell survival (target of belimumab)
• IL-17: Elevated in SLE nephritis; promotes renal inflammation
• IL-10: Paradoxically elevated in SLE - promotes autoreactive B cell survival despite being "anti-inflammatory"
• TNF-alpha: Complex role - may be protective (promoting apoptotic clearance) but drives organ inflammation
• Some autoantibodies in SLE directly target signaling cytokines, acting as natural immunomodulators

Systemic Sclerosis (Scleroderma / SSc)

• TGF-beta: The master fibrotic cytokine - activates fibroblasts, stimulates collagen synthesis, promotes myofibroblast differentiation in skin, lungs, and heart
• IL-4 and IL-13: Th2 cytokines that amplify TGF-beta-driven fibrosis
• IL-6: Promotes fibroblast activation; elevated levels predict worse lung disease
• CXCL4 (PF4): A chemokine elevated early in SSc; correlates with lung fibrosis and pulmonary hypertension
• VEGF: Paradoxically elevated but ineffective - drives abnormal vascular remodeling and pulmonary arterial hypertension (PAH)

Rheumatoid Arthritis (RA) - Systemic Manifestations

• IL-6: Causes anaemia of chronic disease (induces hepcidin, reducing iron availability); elevated CRP/ESR; fatigue; constitutional symptoms
• TNF-alpha: Cachexia (muscle/fat wasting), cardiovascular risk (accelerates atherosclerosis)
• IL-1beta: Bone loss, cartilage catabolism, fever
• Elevated cardiovascular mortality in RA is partly mediated by chronic cytokine-driven endothelial dysfunction and accelerated atherosclerosis

4. Haemophagocytic Lymphohistiocytosis / Macrophage Activation Syndrome (HLH/MAS)

• Failure of cytotoxic T cells and NK cells to eliminate virally infected cells (e.g., EBV) creates a positive feedback loop
• Massive overproduction of cytokines - especially IFN-gamma, IL-6, IL-18, IL-12, TNF-alpha - drives uncontrolled macrophage activation
• Macrophages consume normal marrow elements (hemophagocytosis), causing cytopenias
• Systemic inflammation, coagulopathy (DIC), hepatic failure, and CNS involvement follow

"Failure to kill virally infected cells elicits a positive feedback loop that leads to overproduction of cytokines and excessive activation of macrophages, which often consume normal marrow elements." - Robbins & Kumar Basic Pathology

• Ferritin (>500 µg/L; often >10,000 µg/L in HLH) - reflects macrophage activation
• sCD25 (soluble IL-2 receptor) - T cell activation marker; elevated
• IL-18: Markedly elevated - distinguishes primary HLH from MAS
• IFN-gamma: Drives macrophage activation; target of emapalumab in primary HLH

5. Systemic Inflammation in Gastrointestinal Disease

Inflammatory Bowel Disease (IBD)

• Extraintestinal manifestations (EIMs): Arthritis, uveitis, skin lesions (erythema nodosum, pyoderma gangrenosum) - all cytokine-mediated
• TNF-alpha: The key driver; elevated in mucosa and circulation; anti-TNF therapy (infliximab) revolutionized IBD care
• IL-23/IL-17 axis: Genetic variants in IL-23R associated with Crohn's disease; drives mucosal and systemic inflammation
• IL-6: Systemic acute-phase response; anaemia of chronic disease
• IL-10 deficiency (genetic): Causes severe early-onset IBD by removing the key anti-inflammatory brake

Liver Disease (Hepatic Cytokine Effects)

• TNF-alpha and IL-6 drive hepatic stellate cell activation → cirrhosis and fibrosis in chronic viral hepatitis, NASH
• IL-6: Hepatocyte growth factor (hepatoprotective in acute injury but pro-oncogenic in chronic HCC)
• In NASH/metabolic-associated fatty liver disease (MAFLD): TNF-alpha and IL-6 produced by visceral adipose tissue macrophages drive hepatic steatosis, insulin resistance, and progression to cirrhosis

6. Cytokines in Renal Disease

• Pro-inflammatory cytokines (IL-1, TNF, IL-6): Produced by macrophages infiltrating the renal interstitium; generate ROS and nitric oxide that directly damage tubular cells; correlate with degree of renal dysfunction
• TGF-beta: The dominant pro-fibrotic cytokine in the kidney - promotes epithelial-to-mesenchymal transition (EMT) of tubular cells into fibroblasts, depositing collagen in the interstitium
• Chemokines (CCL2/MCP-1): Recruit monocytes/macrophages into the interstitium, amplifying inflammation
• Tubule epithelial cells themselves synthesize cytokines and chemokines when exposed to excess filtered protein (proteinuria), activating local DCs and T cells

"Direct damage to resident cells is caused through the generation by macrophages of reactive oxygen species, nitric oxide, complement factors, and proinflammatory cytokines. Macrophages can also affect the supporting matrix and vasculature through the expression of metalloproteinases and vasoactive peptides." - Brenner & Rector's The Kidney

7. Cytokines in Cancer (Systemic Effects)

• Cachexia / cancer wasting: TNF-alpha and IL-6 drive profound muscle and fat catabolism
• Anaemia of chronic disease: IL-6 induces hepcidin, blocking iron mobilization
• Fever: IL-1, IL-6, TNF act as endogenous pyrogens
• Hypercalcaemia: PTHrP + IL-6 drive osteoclast activation (myeloma, solid tumours)

8. Cytokines in Cardiovascular and Metabolic Disease

• IL-6, TNF-alpha, IL-1beta: Promote endothelial activation, VCAM-1/ICAM-1 upregulation, monocyte recruitment into plaques
• CANTOS trial (canakinumab, anti-IL-1beta): Reduced cardiovascular events independently of lipid lowering - confirming the causal role of IL-1beta in atherosclerosis
• IL-18: Destabilizes atherosclerotic plaques; promotes vulnerable plaque formation

• Visceral adipose tissue macrophages produce IL-6 and TNF-alpha chronically
• TNF-alpha inhibits insulin receptor signaling (serine phosphorylation of IRS-1) → insulin resistance
• IL-6 induces hepatic insulin resistance
• Adiponectin (an anti-inflammatory adipokine) is reduced in obesity, removing its protective cytokine-suppressing effects

9. Cytokines in Neurological Disease

• Type I interferons (IFN-beta): Pathogenic in multiple sclerosis (MS); IFN-beta therapy reduces relapse by modulating Th1/Th17 activity
• IL-17: Elevated in MS plaques; promotes blood-brain barrier disruption
• TNF-alpha, IL-1, IL-6: Elevated in CSF during neuroinflammation (encephalitis, MS)
• Sepsis-associated encephalopathy: Systemic cytokine spillover into the CNS causes confusion and coma in sepsis (occurs in the majority of septic patients with MODS)
• Alzheimer's disease: Microglia produce IL-1beta, TNF-alpha, and IL-6 in response to amyloid-beta; chronic neuroinflammation accelerates neurodegeneration

Summary: Cytokine Roles Across Systemic Diseases

• Janeway's Immunobiology 10e - Acute-phase response, type I interferons, systemic cytokine effects
• Bailey & Love's Surgery - Sepsis, SIRS, MODS pathophysiology
• Firestein & Kelley's Textbook of Rheumatology - Autoimmune disease cytokine networks
• Rheumatology (Elsevier 2022) - SLE, complement, autoimmune cytokine loops
• Brenner & Rector's The Kidney - Renal interstitial cytokines, TGF-beta, fibrosis
• Robbins & Kumar Basic Pathology - HLH/macrophage activation syndrome
• Recent literature: 2025 cytokine storm review | EULAR/ACR HLH guidelines (PMID: 37487610)

What's inside — 11 slides

Anaesthetic Management in Laparoscopic Surgery

1. Key Principle

2. Pneumoperitoneum — The Core Challenge

Why CO₂?

• Highly soluble in blood - rapidly cleared by the lungs even if accidentally injected intravascularly
• Non-flammable and non-oxidising - safe with electrocautery
• Rapidly metabolised and excreted

3. Physiologic Effects (The Anaesthetic Core Knowledge)

A. Cardiovascular Effects

"Severe hypotension during pneumoperitoneum should be treated with desufflation and may require conversion to an open procedure." - Barash Clinical Anesthesia 9e

B. Respiratory Effects

C. Regional Perfusion Effects

• Renal: ↓ RBF, ↓ GFR, ↑ vasopressin, renin-angiotensin activation → oliguria. IAP >15 mmHg associated with postoperative AKI
• Splanchnic/Hepatic: ↓ intestinal and hepatic flow from compression. Bowel ischaemia risk in prolonged cases
• CNS: ↑ ICP and ↑ cerebral blood flow from Trendelenburg + hypercarbia. Extreme caution in patients with cerebrovascular disease
• Ocular: ↑ IOP in steep Trendelenburg - rare risk of postoperative ischaemic optic neuropathy/blindness

4. Preoperative Assessment

Cardiovascular

• History of IHD, heart failure, valvular disease → cardiology review
• Uncontrolled hypertension → optimise before elective surgery
• Poor LV function: pneumoperitoneum may not be tolerated - consider open approach
• ECG, ECHO as indicated. Arterial line for high-risk patients

Respiratory

• Severe COPD/asthma: may not tolerate CO₂ retention and increased airway pressures
• Obesity (BMI >40): highest risk group - difficult airway + hypoxaemia + atelectasis + ↑ complications
• Pulmonary hypertension: elevated IAP may critically reduce RV output
• OSA: CPAP continuation; post-op monitoring essential

Airway

• Obesity and anatomical factors → full airway assessment (Mallampati, thyromental distance, neck mobility)
• RSI for high aspiration risk (obese, hiatus hernia, full stomach)
• Consider awake fibreoptic bronchoscopy if predicted difficult airway

Patient Preparation

• NBM: solids 6h, clear fluids 2h (ERAS)
• DVT prophylaxis: TED stockings + LMWH
• Pre-oxygenation: 3 min tidal breathing or 8 vital capacity breaths
• Antacid premedication where indicated
• Inform patient about shoulder-tip pain from diaphragmatic CO₂ irritation

5. Intraoperative Anaesthetic Management

Induction

• Standard IV induction: propofol + fentanyl/remifentanil
• RSI (suxamethonium or high-dose rocuronium) for aspiration risk
• Cuffed ETT mandatory for pneumoperitoneum cases
• Confirm position - bilateral air entry - recheck after insufflation and positioning

Maintenance

• TIVA (propofol infusion) preferred over volatile agents - significantly reduces PONV, avoids N₂O
• Avoid N₂O - causes bowel distension and worsens PONV
• Remifentanil infusion for intraoperative analgesia
• Sevoflurane acceptable where TIVA not available

Muscle Relaxation - Critical for Laparoscopy

• Improves surgical access and visualisation
• Allows lower insufflation pressures → less physiological derangement
• Monitor with TOF (train-of-four) or PTC (post-tetanic count)
• Reverse fully before extubation - sugammadex preferred for rocuronium reversal
• NMB assessment can be highly subjective - always use nerve stimulator

Monitoring — Mandatory

6. Mechanical Ventilation Strategy

• Increase minute ventilation after insufflation to compensate for CO₂ absorption
• Sudden ETCO₂ spike → suspect subcutaneous emphysema or gas embolism
• Recruitment manoeuvres (30-40 cmH₂O for 30s) for refractory hypoxaemia
• At end of procedure: hand ventilate to expel residual peritoneal CO₂

7. Fluid Management & Temperature

• Goal-directed fluid therapy (GDFT) based on dynamic flow parameters
• Avoid over-hydration - worsens airway oedema (critical in prolonged Trendelenburg)
• Target urine output >0.5 mL/kg/hr (>2 mL/kg/hr reassuring)
• No evidence for furosemide, mannitol, or "renal-dose" dopamine in AKI prevention
• Active patient warming mandatory - CO₂ gas causes significant heat loss
  • Forced-air warming blanket
  • Warm IV fluids and blood products
  • Heated and humidified CO₂ insufflation where available
  • Target normothermia 36-37.5°C

8. Complications — Recognition and Management

Intraoperative

• CO₂ enters venous system via open vessel during insufflation
• Signs: sudden ↓ ETCO₂ (large embolus), "mill-wheel" murmur, ↓ SpO₂, cardiovascular collapse
• Management: desufflate immediately, left lateral Trendelenburg, 100% O₂, aspirate via CVP line, CPR if arrest

• Trocar or Veress needle injury - rare (~0.5%) but high mortality
• Sudden haemodynamic collapse, distending abdomen
• Immediate call for help, open conversion, blood products

• Hypotension: reduce IAP, fluid bolus, vasopressor (phenylephrine, vasopressin, ephedrine)
• Hypertension: deepen anaesthesia, antihypertensives
• Dysrhythmias: correct hypercarbia; atropine for bradycardia (vagal from peritoneal stretch)

• ETT migration into right main bronchus → reconfirm position after any position change
• ↑ Airway pressure → check tube, consider bronchospasm or pneumothorax
• Tension pneumothorax: immediate needle decompression

• CO₂ tracking into subcutaneous tissue
• Manifests as crepitus, ↑ ETCO₂ unresponsive to ↑ ventilation
• Reduce IAP; usually resolves spontaneously

Postoperative

9. Postoperative Analgesia — Multimodal (Opioid-Sparing)

• Paracetamol 1g QDS — regular, baseline
• NSAIDs (ketorolac, ibuprofen, diclofenac) — unless contraindicated
• Port-site local anaesthetic infiltration - bupivacaine/levobupivacaine at all incision sites
• TAP block (Transversus Abdominis Plane block) - for larger/more painful laparoscopic procedures
• Low-dose IV ketamine (0.1-0.3 mg/kg/hr) - reduces opioid consumption
• Intraperitoneal LA instillation - low risk, some evidence for benefit
• Minimise systemic opioids - drives PONV, ileus, respiratory depression

10. PONV Prevention (APFEL Score)

1. Female sex
2. Non-smoker
3. History of motion sickness or previous PONV
4. Postoperative opioid use

• Ondansetron 4 mg IV at end of surgery
• Dexamethasone 4-8 mg IV at induction
• Droperidol 0.625-1.25 mg IV
• Scopolamine patch for high-risk
• TIVA (propofol) significantly reduces baseline PONV risk vs. volatiles

11. Special Groups

Obese Patients (BMI >40)

• Ramped position at induction (ear-sternal notch alignment)
• RSI routine - aspiration risk
• Pressure-controlled ventilation preferred
• Higher PEEP (up to 10-12 cmH₂O)
• Reverse Trendelenburg for upper abdominal surgery (improves FRC)
• BMI >40 + comorbidities = significantly ↑ laparoscopic complications

Robotic-Assisted Laparoscopy

• Prolonged steep Trendelenburg = magnified physiological derangement
• Limited patient access during surgery - pre-agree emergency undocking protocol with surgeon
• Risk of airway oedema and cerebral oedema - consider extubation in theatre
• Postoperative visual loss risk - limit total steep Trendelenburg duration

Ambulatory Laparoscopy

• Short-acting agents: propofol TIVA, desflurane
• Multimodal analgesia to avoid opioid-heavy regimens
• Strict PONV prophylaxis before discharge
• Aldrete score ≥9 + VAS pain ≤4 for discharge criteria

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Anaesthetic Management Laparoscopic Surgery

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