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Anaesthetic Management of a Pregnant Patient with Severe Anaemia Posted for Elective LSCS

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1. Evaluation

Definition and Classification

History

• Duration, onset, and likely aetiology (iron deficiency, folate/B12 deficiency, haemoglobinopathy, haemolytic, aplastic)
• Symptoms: dyspnoea at rest or minimal exertion, palpitations, chest pain, syncope - indicative of decompensation
• Dietary intake, pica, worm infestation (common causes in the developing world)
• Previous blood transfusions (alloimmunisation risk)
• Drug history (NSAIDs, haematinics compliance, antimalarials)
• Obstetric history: placenta praevia, previous PPH, grand multiparity

Physical Examination

• Pallor of conjunctivae, palms, mucous membranes - grades the clinical severity
• Signs of cardiac compensation: tachycardia, wide pulse pressure, hyperdynamic precordium, haemic murmur, cardiomegaly
• Features of high-output cardiac failure: bibasal crackles, raised JVP, peripheral oedema
• Jaundice (haemolytic cause), koilonychia/angular stomatitis (iron deficiency), neurological deficits (B12 deficiency)
• Airway assessment (Mallampati, thyromental distance, neck mobility - mandatory pre-LSCS)
• Spine assessment for neuraxial access

Investigations

• Complete blood count with indices (MCV, MCH, MCHC, RDW)
• Peripheral smear - morphology guides aetiology (hypochromic microcytes, target cells, sickle cells, spherocytes)
• Reticulocyte count
• Serum iron, TIBC, ferritin (iron stores), serum B12 and folate
• Hb electrophoresis if haemoglobinopathy suspected

• LFTs, RFTs, serum electrolytes
• Coagulation profile (PT, aPTT, platelet count) - haemolytic anaemias may coexist with thrombocytopenia (Evans syndrome, HELLP)
• Urine examination (urinary tract infection exacerbating anaemia; proteinuria)
• Blood grouping and crossmatch - hold 2-4 units packed red blood cells (PRBC) pre-operatively
• Indirect Coombs test if haemolytic or prior transfusion history

• ECG: tachycardia, signs of myocardial ischaemia, LVH (in long-standing anaemia)
• Echocardiography if signs of cardiac decompensation, suspected cardiomyopathy, or Hb <6 g/dL - assess LVEF, wall motion, pericardial effusion

• Cardiotocography (CTG) - fetal compromise is more likely when maternal Hb <6 g/dL due to reduced oxygen delivery
• Biophysical profile and umbilical artery Doppler if indicated

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2. Preoperative Preparation

Treat the Underlying Cause

• Oral ferrous sulphate 200 mg three times daily (absorbed if gut normal; takes 6-8 weeks)
• Intravenous iron (ferric carboxymaltose 1000 mg single infusion, or iron sucrose 200 mg multiple sessions) is preferred when oral iron is not tolerated, malabsorption exists, time is limited (<4 weeks), or Hb <8 g/dL. IV iron increases Hb by approximately 1-2 g/dL over 2-4 weeks. Recent evidence confirms IV iron is superior to oral iron in restoring Hb in the perioperative obstetric patient. [PMID: 36794901]
• Folic acid 5 mg/day for megaloblastic component
• Vitamin B12 injection (1000 mcg IM) if deficient

Patient Blood Management (PBM) - Three Pillars

1. Optimise Hb preoperatively as above
2. Minimise intraoperative blood loss: meticulous surgical technique, oxytocin infusion, tranexamic acid 1 g IV before skin incision (now standard per WHO, evidence from WOMAN-2 trial)
3. Optimise physiological tolerance of anaemia: maintain normovolaemia, normothermia, adequate oxygenation

Transfusion Planning

• If Hb remains <7 g/dL despite treatment AND patient is symptomatic or surgery cannot be postponed further, consider pre-operative PRBC transfusion to achieve at least Hb 8-10 g/dL before elective LSCS
• Type and screen mandatory; 2-4 units PRBC crossmatched and available in theatre
• Discuss with haematologist in haemoglobinopathy (sickle cell: exchange transfusion may be needed to reduce HbS to <30%)
• Consent patient for blood and blood products including autologous/allogenic options

Multidisciplinary Team

• Obstetric anaesthetist, obstetrician, haematologist, neonatologist
• Intensive care/HDU bed should be arranged preoperatively if Hb <7 g/dL or signs of cardiac failure
• Intraoperative cell salvage setup should be considered - safe in obstetrics when leucodepletion filter is used (controversial but increasingly accepted)

Fasting and Aspiration Prophylaxis

• 6 hours solid food, 2 hours clear fluids
• Antacid prophylaxis (all obstetric patients undergoing LSCS, regardless of anaesthetic technique):
  • Ranitidine 150 mg orally the night before and 2 hours pre-op (or IV on arrival)
  • Metoclopramide 10 mg IV pre-op (promotility, reduces aspiration risk)
  • Sodium citrate 30 mL orally in theatre (non-particulate antacid - immediate acting)

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3. Anaesthetic Management

General Principles

• Reduced functional residual capacity (FRC) and increased oxygen consumption - predisposing to rapid desaturation
• Full stomach from 18-20 weeks gestation (increased aspiration risk)
• Aortocaval compression in supine position - left uterine displacement is mandatory
• Airway oedema and friability - Mallampati grade often worsens in labour

• Reduced oxygen-carrying capacity with minimal reserve
• Compensatory high-output state (tachycardia, increased CO) - vasodilation or vasopressors must be used judiciously
• Risk of decompensation with even modest haemodynamic perturbation

Choice of Anaesthetic Technique

Neuraxial Anaesthesia - PREFERRED

• Avoids GA and its risks (difficult airway, failed intubation, pulmonary aspiration, fetal drug exposure)
• Reduces surgical blood loss compared to GA (sympathectomy reduces venous engorgement in pelvis)
• Maintains maternal airway reflexes
• Allows mother to be awake; no fetal drug transfer

• Hyperbaric bupivacaine 0.5%: 1.8-2.2 mL (10-11 mg) intrathecally at L3-L4 or L4-L5
• Fentanyl 15-25 mcg intrathecally (augments block, reduces dose of bupivacaine needed)
• Morphine 100-150 mcg intrathecally (postoperative analgesia - up to 24 hours)
• Target sensory level to T4 (loss of cold sensation at the 4th intercostal space level)

• Left uterine displacement throughout (15-degree left lateral tilt or wedge under right hip)
• Phenylephrine infusion is the vasopressor of choice (100 mcg/min starting infusion titrated to maintain systolic BP within 20% of baseline) - superior to ephedrine as it causes less fetal acidosis (Miller's Anesthesia, 10e, p. 8863)
• Crystalloid co-load 10-15 mL/kg Ringer's lactate rapidly at time of spinal injection - more effective than pre-load
• Colloid pre-load (500 mL colloid) may be considered but concerns exist about synthetic colloids; avoid large volumes in suspected cardiac dysfunction
• Avoid Trendelenburg positioning (reduces FRC further, worsens oxygenation)

• Slower onset allows more gradual titration - beneficial if cardiovascular compromise is present
• Catheter technique allows incremental dosing and extension if surgery is prolonged
• Combination spinal-epidural (CSE) is an excellent option: provides dense spinal block with ability to extend via epidural catheter
• Useful in cases where prolonged surgery is anticipated or there is concern about fixed cardiac output

General Anaesthesia - Reserved for Specific Indications

• Maternal refusal of neuraxial
• Coagulopathy (platelet count <80,000 or INR >1.5)
• Severe hypovolaemia
• Sepsis with haemodynamic instability
• Failed or inadequate neuraxial block
• Urgent/emergency (Category 1) caesarean

• Preoxygenation is absolutely mandatory: 3 minutes of tidal breathing with 100% O2 or 4 vital capacity breaths via tight-fitting mask
• In anaemia, FRC is already the only O2 reserve - do not compromise pre-oxygenation
• Rapid Sequence Induction (RSI) with cricoid pressure
  • Induction agent: thiopentone 4-5 mg/kg IV OR propofol 2-2.5 mg/kg IV
  • Muscle relaxant: succinylcholine 1.5 mg/kg IV (agent of choice for RSI in obstetrics)
  • If succinylcholine contraindicated: rocuronium 1.2 mg/kg IV with sugammadex available
• Ketamine 1-2 mg/kg IV is an alternative induction agent when haemodynamic compromise exists - maintains sympathetic tone, supports BP (avoid if severely hypertensive)
• Intubation with cuffed ETT (size 6.5-7.0); video laryngoscopy should be immediately available given the known risk of difficult intubation in obstetrics (1:300 cases)
• Maintenance: isoflurane/sevoflurane 0.5-1 MAC + 50% N2O in O2 or air; avoid high volatile agent concentrations (>1 MAC) before delivery as they relax uterus and increase blood loss
• Avoid N2O if severe anaemia and concern about tissue hypoxia - use air-O2 mix to maintain FiO2 > 0.5
• After delivery: increase anaesthetic depth, add opioids (fentanyl/morphine), oxytocin 5 IU slow IV then infusion 20-40 IU in 500 mL saline

Intraoperative Monitoring

Blood and Fluid Management

• Target Hb ≥ 8 g/dL intraoperatively in severe anaemia; lower threshold may worsen cardiac outcomes
• Crossmatched blood must be in theatre - ready to hang
• Cell salvage: set up intraoperatively, particularly if haemoglobinopathy, refusal of allogenic blood, or anticipated major blood loss (prior uterine scar, fibroids, placenta praevia)
• Tranexamic acid 1 g IV over 10 min at skin incision, repeated if ongoing blood loss at 30 minutes - reduces PPH by 31% (WOMAN trial; WOMAN-2 in elective CD)
• Oxytocin 5 IU slow IV bolus after cord clamping then 20-40 IU infusion (avoid rapid bolus in cardiac compromise - causes vasodilation and hypotension)
• Maintain normovolaemia with balanced crystalloids; avoid hypervolaemia (risk of pulmonary oedema in low-Hb states with compensatory high-output circulation)

Postoperative Management

• Recovery in HDU/ICU level care if Hb remained <7 g/dL at end of surgery or if haemodynamic instability
• Monitor SpO2, BP, urine output, blood loss, uterine tone continuously for at least 4 hours
• Supplemental oxygen (4-6 L/min via face mask) for at least 6-12 hours
• Reassess Hb and haematocrit 4-6 hours post-op; transfuse if Hb <7 g/dL with symptoms or <6 g/dL regardless
• Postoperative analgesia: multimodal (intrathecal morphine + paracetamol + diclofenac if no contraindication + tramadol if needed) - minimise systemic opioids to preserve respiratory drive
• IV iron therapy postpartum (ferric carboxymaltose) if oral iron not tolerated
• VTE prophylaxis: LMWH 6-12 hours after neuraxial block removal (anaemia is not a contraindication to VTE prophylaxis; timing guided by ASRA/OAA guidelines)
• Breastfeeding support and neonatal team review

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4. Key Anaesthetic Considerations Summary

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Recent Literature

• [PMID 36794901] - Wiesenack et al., Curr Opin Anaesthesiol (2023): Comprehensive review confirming IV iron as the preferred treatment for preoperative IDA in obstetric patients; intraoperative cell salvage is safe and effective in obstetrics.
• [PMID 38670490] - Moral et al., Rev Esp Anestesiol Reanim (2024): Delphi consensus recommending systemic preoperative anaemia screening and treatment protocols in all elective surgery.
• [CPOC UK Guidelines 2022]: Three-pillar Patient Blood Management framework for perioperative anaemia endorsed for all elective surgical specialties including obstetrics.

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Perioperative Anaesthetic Management of a Morbidly Obese Parturient Posted for Elective LSCS

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Definitions

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1. Preoperative Evaluation

Antepartum Consultation (Ideally at 28-34 Weeks)

• Assess comorbidities and formulate a multidisciplinary care plan
• Anticipate potential anaesthetic difficulties before an emergency situation arises
• Ensure appropriate equipment is available

History

• Obstructive sleep apnoea (OSA): snoring, witnessed apnoeas, daytime somnolence, use of CPAP/BiPAP - present in up to 30% of morbidly obese parturients
• Gestational diabetes mellitus (prevalence 6-14% in obese parturients)
• Hypertensive disorders: gestational hypertension, pre-eclampsia (14-25% prevalence)
• Gastro-oesophageal reflux disease (GORD) - almost universal
• Ischaemic heart disease, peripartum cardiomyopathy
• Venous thromboembolism history
• STOP-BANG questionnaire for OSA screening (BMI >35 is one criterion)

• Previous LSCS - wound/scar complications
• Grand multiparity
• Macrosomia (associated with shoulder dystocia in vaginal delivery)

Physical Examination

• Mallampati classification (often grades III-IV in obese pregnant women)
• Mouth opening, thyromental distance, neck circumference (>40 cm = OSA risk)
• Neck mobility, jaw protrusion
• Breast size and chest AP diameter (short-handled laryngoscope may be needed)
• Note: Pregnancy-associated weight gain + large breasts + airway oedema of pregnancy = compound difficult airway
• Airway oedema is worsened by pre-eclampsia (more common in obese patients)

• BP (hypertensive disease very common)
• Cardiac: signs of LVH, cardiomegaly, cardiac failure (obese parturients have increased LV mass, LV wall thickness, LA size)
• Respiratory: SpO2, lung auscultation, signs of pulmonary hypertension
• Back: skin folds, bony landmarks (for neuraxial access planning)
• BMI calculation, weight (for drug dosing)
• Venous access assessment

Investigations

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2. Preoperative Preparation

Optimise Co-morbidities

• BP control (target <140/90 mmHg; <160/110 if pre-eclamptic)
• Glycaemic control: maintain perioperative glucose 6-10 mmol/L
• CPAP/BiPAP: continue prescribed CPAP and ensure available in recovery/HDU
• Treat GORD: proton pump inhibitor course preoperatively
• Anaemia correction (see previous topic)
• VTE prophylaxis: LMWH (weight-adjusted dosing) and TED stockings from admission; plan timing around neuraxial

Theatre and Equipment Planning

• Operating table capacity: standard tables may support only 135-180 kg; bariatric tables support 300-500 kg - confirm table capacity before listing
• Ramped position: have blankets/foam ramp or use Jackson table head elevation to achieve the "ramp" (ear aligned with sternal notch) before any GA is attempted
• Transfer board and staff: minimum 4-6 staff members needed to transfer patient safely
• Wider blood pressure cuff (thigh cuff for upper arm if arm is too large)
• Arterial line kit immediately available
• Video laryngoscope (e.g. C-MAC, McGrath, GlideScope) - should be immediately available for ALL obstetric GAs, especially obese patients
• Short-handled laryngoscope
• Difficult airway trolley with supraglottic airway devices (i-gel, ProSeal LMA), videolaryngoscope, bougie, fibreoptic scope, surgical airway equipment
• Long epidural/spinal needles (standard needles may be insufficient at BMI >40)
• Ultrasound machine for neuraxial guidance and IV access
• Intraoperative cell salvage considered

Aspiration Prophylaxis

• Ranitidine 150 mg PO the night before and 2 hours pre-op
• Metoclopramide 10 mg IV (promotility)
• Sodium citrate 30 mL PO in theatre (non-particulate antacid, immediate onset)
• Proton pump inhibitor (omeprazole 40 mg PO pre-operatively if on regular PPI)

Fasting: Standard - 6 hours solids, 2 hours clear fluids

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3. Anaesthetic Management

Physiological Considerations Specific to Morbid Obesity in Pregnancy

Positioning

• Left uterine displacement mandatory (15° left tilt with wedge under right hip) from the moment the patient lies supine
• For airway management (GA): ramped position (ear aligned with sternal notch), head elevated 20-30°
  • This improves laryngoscopic view, increases apnoea time by increasing FRC, and facilitates intubation
  • Use purpose-built foam ramp or stack of blankets under head, neck and shoulders
• For neuraxial block: sitting position is generally preferred for obese patients as it helps identify the midline; lateral position with hip flexion is an alternative

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A. NEURAXIAL ANAESTHESIA - TECHNIQUE OF CHOICE

Why Neuraxial is Critical in the Obese Parturient

• Difficult/failed intubation is reported in 33% of obese parturients undergoing GA for caesarean (vs 13% in non-pregnant obese patients)
• Rapid desaturation occurs faster due to markedly reduced FRC + increased O₂ consumption
• A functioning neuraxial block also avoids the cardiovascular depression, neonatal drug transfer, and prolonged emergence of GA
• Well-functioning labour epidural can be extended to surgical anaesthesia for LSCS, avoiding GA entirely

Technical Challenges with Neuraxial in Obesity

• Deep skin-to-epidural space distance (mean 7.5 cm in morbid obesity vs 5 cm in normal weight; may reach 8 cm)
• Bony landmarks obscured by subcutaneous fat - midline identification difficult
• Standard epidural needles (8 cm/80 mm) may be insufficient - 10 cm (100 mm) Tuohy needles may be required
• Higher failure rate: obese patients are more likely to require epidural top-up, catheter manipulation, or repeat procedure
• Epidural fat increases in obesity - local anaesthetic may spread unpredictably, potentially causing a higher-than-expected block

Recommended Technique: Combined Spinal-Epidural (CSE)

• Epidural Tuohy needle is easier to introduce into fat-distorted anatomy than a spinal needle alone
• Once Tuohy is in epidural space, it guides the spinal needle through needle (needle-through-needle technique)
• Provides dense, fast-onset spinal block for surgery
• Epidural catheter allows:
  • Incremental top-up if surgery is prolonged (common in obese patients - longer operating time expected)
  • Titration of the block level upward if spinal insufficient
  • Postoperative epidural analgesia
• Lower intrathecal bupivacaine dose can be used (cardiovascular safety)

• Position: sitting preferred (identifies midline better in obese patients)
• Level: L3-L4 or L2-L3 (L4-L5 may be needed if higher levels inaccessible)
• Use ultrasound guidance pre-procedurally to identify the intervertebral level and depth to the epidural space
• Intrathecal component: hyperbaric bupivacaine 0.5% 8-10 mg (lower dose than non-obese - 11-12 mg - due to reduced CSF volume from distended epidural veins and increased epidural fat causing enhanced cephalad spread)
• Fentanyl 15-20 mcg intrathecally
• Morphine 100 mcg intrathecally (postoperative analgesia)
• Epidural catheter: thread 4-5 cm into epidural space; test with 3 mL 2% lidocaine + 1:200,000 adrenaline (test dose)

• Alternative if CSE not feasible
• Note: pencil-point spinal needle alone may be technically difficult in deep, fat-distorted anatomy
• Use standard bupivacaine doses with caution - risk of high/total spinal is slightly higher due to reduced CSF volume

• Emerging technique: dura punctured with a 25G spinal needle via Tuohy without intrathecal injection, then epidural loaded
• Combines benefits of epidural (gradual titration, catheter) with improved dural transfer of drugs
• Favorable safety profile in the 2026 meta-analysis - particularly in morbidly obese patients

• Left uterine displacement maintained throughout
• Phenylephrine prophylactic infusion: 50-100 mcg/min starting immediately after spinal, titrated to BP
  • Phenylephrine is vasopressor of choice over ephedrine (less fetal acidosis)
• Norepinephrine infusion (5-10 mcg/min) is an emerging alternative with similar efficacy and comparable safety to phenylephrine
• Crystalloid co-load (15 mL/kg Ringer's lactate) at time of spinal injection
• Note in obese patients: sympathectomy from spinal anesthesia + aortocaval compression from panniculus = severe hypotension risk; have vasopressor drawn up and running before proceeding

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B. EPIDURAL ANAESTHESIA ALONE

• Appropriate if a well-functioning labour epidural is already in situ
• Incremental top-up: 2% lidocaine with 1:200,000 adrenaline, 5 mL aliquots to achieve T4-T6 level
• Alternative: bupivacaine 0.5% + fentanyl 50-100 mcg epidurally in divided doses
• Advantages: gradual BP changes (less hypotension than spinal), adjustable, catheter left in situ postoperatively
• Disadvantage: risk of inadequate or patchy block; catheter must be verified before surgical start

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C. GENERAL ANAESTHESIA - RESERVED FOR SPECIFIC INDICATIONS

• Maternal refusal of neuraxial
• Coagulopathy (platelets <80,000 or INR >1.5)
• Severe haemodynamic instability/hypovolaemia
• Failed/inadequate neuraxial despite attempts
• Category 1 emergency where time to neuraxial is prohibitive
• Previous spinal surgery with extensive scarring

Pre-induction Setup (Never Skip)

1. Confirm theatre team (minimum 2 anaesthetists for obese patients in GA)
2. Ramped position (ear-sternal notch alignment)
3. Video laryngoscope set up and working (OAA/DAS guidelines: video laryngoscope immediately available for all obstetric GAs)
4. Difficult airway trolley at bedside: bougie, multiple ETT sizes (6.0-7.0 mm ID), short-handled laryngoscope, supraglottic airway devices (ProSeal LMA, i-gel), fibreoptic scope, front-of-neck access equipment
5. Dedicated assistant for cricoid pressure
6. Invasive arterial monitoring (arterial line): strongly recommended in morbidly obese parturients undergoing GA
7. SpO2, ETCO2, large-bore IV access (2 lines)

Preoxygenation - Maximise it

• 3 minutes of tidal breathing with 100% O₂ at 10 L/min via tight-fitting mask OR
• 4-8 maximal vital capacity breaths at 100% O₂
• Ramp head-up 20-30° during preoxygenation (increases FRC, delays desaturation)
• Target SpO2 ≥98% before induction
• In morbidly obese patients, apnoea time to SpO2 90% is drastically reduced (as little as 50-90 seconds vs 3-4 minutes in normal-weight individuals)

Rapid Sequence Induction (RSI)

• Thiopentone 5-7 mg/kg lean body weight (LBW) OR propofol 2-2.5 mg/kg LBW (avoid pure total body weight dosing to prevent cardiovascular depression)
• Succinylcholine 1.5 mg/kg TOTAL body weight (TBW) - pseudocholinesterase activity scales with TBW
• If succinylcholine contraindicated: rocuronium 1.2 mg/kg LBW with sugammadex 16 mg/kg TBW available for reversal
• Cricoid pressure (Sellick manoeuvre) - apply 10N pre-induction, 30N after loss of consciousness, release on confirmed intubation
• Video laryngoscope as first-line (not fallback) in morbidly obese parturients

Drug Dosing Principles (from Barash 9e Table 45-3)

• LBW (men) = 9270 × TBW / (6680 + 216 × BMI)
• LBW (women) = 9270 × TBW / (8780 + 244 × BMI)
• IBW (women) = 45.5 + 2.3 × (height in inches - 60)

Maintenance of Anaesthesia

• Sevoflurane/isoflurane 0.5-1 MAC in O₂/air mixture
• Avoid >1 MAC volatile agent before delivery (uterine relaxation → increased blood loss)
• Aim FiO₂ 0.5 (50% O₂, 50% air) - balance between oxygenation and absorption atelectasis
• Avoid N₂O in morbidly obese (worsens hypoxaemia from atelectasis, causes bowel distension, increases PONV)
• Maintain normocapnia (PaCO₂ 28-34 mmHg) - avoid hypo- or hyperventilation
• After delivery: fentanyl 1-2 mcg/kg LBW, increase volatile agent, add oxytocin

Ventilation Strategy

• Tidal volume: 6-8 mL/kg ideal body weight (lung protective ventilation - avoids volutrauma)
• Positive end-expiratory pressure (PEEP): 5-10 cmH₂O (prevents atelectasis, especially in obese patients who have more atelectasis-prone dependent lung zones)
• Recruitment manoeuvre post-intubation: pressure control inflation to 30-40 cmH₂O for 10-15 seconds, then maintain PEEP
• Rate: adjust to maintain normocapnia

Extubation

• Extubate fully awake, with NMB fully reversed (use neostigmine/sugammadex)
• Extubate in semi-recumbent or ramped position (not flat supine - this worsens airway obstruction post-extubation)
• Have supraglottic airway immediately available if airway becomes compromised post-extubation
• After extubation, apply CPAP if patient uses it or if SpO₂ drops

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4. Intraoperative Monitoring

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5. Intraoperative Surgical Considerations

• Panniculus retraction: large abdominal panniculus may need to be retracted upward - this causes further aortocaval compression and respiratory restriction; communicate with surgeon
• Anticipate longer operative time (technically challenging surgery)
• Increased blood loss risk - crossmatched blood must be in theatre
• Tranexamic acid 1 g IV before skin incision (reduces PPH)
• Oxytocin 5 IU slow IV after cord clamping, then infusion (avoid rapid bolus - severe vasodilatation in high-output state)
• Antibiotic prophylaxis: cefazolin dose should be increased to 2-3 g for BMI >30 (standard 1 g is inadequate tissue concentration)
• Wound closure: use barbed suture, consider subcutaneous drain to reduce wound dehiscence risk

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6. Postoperative Management

Immediate Recovery

• All morbidly obese parturients after LSCS should recover in HDU or high-dependency setting (not standard recovery bay) - minimum 12-24 hours monitoring
• Sitting/semi-recumbent position (45°) immediately post-op - improves respiratory mechanics, reduces airway obstruction
• Supplemental O₂ via face mask or Venturi mask (FiO₂ 0.35-0.5); target SpO₂ ≥95%
• Continue CPAP if prescribed (resume immediately post-extubation)
• Continuous SpO₂ monitoring (OSA + opioids = risk of respiratory depression)

Postoperative Analgesia - Multimodal and Opioid-sparing

VTE Prophylaxis

• Morbid obesity is a major independent VTE risk factor; pregnancy compounds this
• LMWH (weight-adjusted): enoxaparin 40 mg SC BD if weight >100 kg (vs standard 40 mg OD for normal weight)
• Start 6-12 hours post-neuraxial, confirm catheter removed
• TED stockings + early mobilisation

Other Postoperative Measures

• Blood glucose monitoring 2-hourly (diabetic patients)
• Monitor for signs of pre-eclampsia/eclampsia postpartum (BP, reflexes, symptoms)
• Haemoglobin check 6-12 hours post-op (anticipate greater blood loss)
• Wound care: inspect daily for wound dehiscence (much more common in obese patients)
• Encourage breastfeeding (weight loss benefit, not contraindicated)
• Discharge planning: referral to bariatric service for post-partum weight management

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7. Key Management Summary Table

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Recent Evidence

• [PMID 41845267] Cao et al., BMC Anesthesiology (2026) - Network meta-analysis of 11 RCTs (1,178 patients): CSE ranked best for preventing neuraxial block failure in obese parturients (OR 0.41 vs standard epidural); DPE offered the best balance of efficacy and safety (particularly for morbidly obese subgroup with BMI ≥40).
• [PMID 37321768] Sivakumar & Karmakar (2023) - Ultrasound-guided spinal sonography significantly improves success rate of neuraxial blocks in obese patients by accurately identifying the epidural space depth and intervertebral level.
• ACOG and RCOG guidelines recommend multidisciplinary team planning (obstetrician, anaesthetist, midwife, neonatologist, bariatric team) for all parturients with BMI ≥40.