Anesthetic Conduct in Palate Repair in a 10-Year-Old Girl with Sickle Cell Disease

Introduction

I. PREOPERATIVE ASSESSMENT

A. SCD-Specific Evaluation

• CBC: baseline Hb, WBC (chronic leukocytosis), platelet count
• HbS% (electrophoresis if not recently done)
• Renal function (creatinine, urea)
• LFTs
• ECG (LV hypertrophy, RV strain)
• Chest X-ray (cardiomegaly, old ACS, pulmonary changes)
• Echocardiogram: if pulmonary hypertension, functional limitation, or ECG abnormality suspected
• ABG if significant pulmonary disease

B. Palatoplasty-Specific Evaluation

• Assess the oral cavity and palatal anatomy carefully
• Evaluate for associated anomalies (syndromes: Robin sequence, Stickler, 22q11 deletion)
• Note degree of mouth opening and neck mobility
• Prior anesthetic records (previous cleft lip repair if done)
• History of URTI (mandatory to postpone if active - risk of laryngospasm and increased airway secretions is especially dangerous here)

II. PREOPERATIVE OPTIMIZATION

A. Transfusion Strategy (Most Critical Decision)

• Target: Raise Hb to >10 g/dL (>100 g/L)
• Simple transfusion (conservative strategy) is as effective as aggressive exchange transfusion for intermediate-risk surgery, per the landmark Preoperative Transfusion in Sickle Cell Disease Study (N Engl J Med, 1995)
• Exchange transfusion is reserved for: high-risk surgery, or when baseline Hb already >10 g/dL (to avoid hyperviscosity by reducing HbS% without raising total Hb excessively)
• Target HbS% reduction to <30% is reserved for high-risk (cardiovascular, intracranial) procedures only
• Decision must be made in concert with a hematologist - designate a lead hematologist as per UK Association of Anaesthetists 2021 guidelines
• Allow time for cross-matching: alloimmunization is common in SCD, cross-matched blood takes time

B. Other Preoperative Measures

• Hydration: Minimize fasting time; schedule as first case of the morning. IV hydration (D5 0.45% NaCl or similar maintenance fluids) from the time of fasting to prevent dehydration and sickling
• Infection: Treat any active infection before proceeding; SCD children are functionally asplenic and highly susceptible
• Hydroxyurea: If the child is on hydroxyurea, continue it
• Incentive spirometry/chest physiotherapy if any pulmonary compromise
• Avoid cold environments in the perioperative period
• Anxiolysis: Oral midazolam 0.5 mg/kg can be given; avoid respiratory depressants in the premedication
• URTI screen: Mandatory. Postpone if any active respiratory infection

III. INTRAOPERATIVE ANESTHETIC CONDUCT

A. Positioning and Setup

• Supine with a shoulder roll (raises shoulders, extends neck) for optimal oral access
• Surgeon uses a Dingman or Boyle-Davis mouth gag with tongue blade - this compresses the tongue and can obstruct the endotracheal tube; ETT position must be re-verified after gag placement
• Head-ring for head stabilization
• Draping tends to isolate the airway from the anesthesiologist - secure the circuit well

B. Airway Management (Shared Airway - Key Challenge)

• Oral RAE (Ring-Adair-Elwyn) preformed tube is the tube of choice - it curves downward and away from the surgical field, exits from the chin, and is fixed to the chin with tape. This keeps the tube out of the surgeon's way
• Size for 10-year-old girl: internal diameter approximately 5.5-6.0 mm cuffed (Cole formula: ID = age/4 + 4 = 6.5; choose a cuffed tube slightly smaller, 5.5-6.0 mm cuffed, appropriate at this age)
• Cuffed tube preferred in this age group - better airway sealing, more reliable capnography, less risk of aspiration of blood
• After placement of the Boyle-Davis gag, re-check tube position and bilateral air entry - the gag can advance the tube into the right main bronchus
• Throat pack: a moist throat pack is placed by the surgeon to prevent blood and debris from passing into the larynx and trachea. It must be documented and removed before extubation (risk of retained throat pack is a serious patient safety issue)

C. Induction

• IV induction preferred (child is 10 years, IV access is feasible)
• Preoxygenation for 3-5 min with 100% O2 (mandatory in SCD to prevent any desaturation)
• Induction agent: Propofol (1.5-2.5 mg/kg IV) or Thiopentone (3-5 mg/kg IV)
• Avoid ketamine as sole agent (increases CMRO2, sympathomimetic effects, increases secretions) - though low-dose ketamine as adjunct for analgesia is acceptable
• Muscle relaxant: Atracurium (0.5 mg/kg) or Vecuronium (0.1 mg/kg) for intubation
  • Succinylcholine: generally avoided in elective cases; acceptable if rapid sequence needed
  • Avoid rocuronium without sugammadex availability
• Intubate with oral RAE tube once adequately relaxed; gentle laryngoscopy to minimize stimulation

D. Maintenance

• Maintain normoxia at all times: SpO2 >95% mandatory. Higher FiO2 (0.4-0.5) is acceptable
• Avoid N2O (nitrous oxide): Contraindicated in SCD. It diffuses into gas spaces (though this is less relevant here), but more importantly it is a bone marrow suppressant, can worsen sickling, and reduces FiO2 available
• Volatile agent: Sevoflurane (preferred in pediatrics, pleasant smell for mask induction if needed, less airway irritation, rapid offset) or isoflurane. Both are acceptable
• Technique: balanced anesthesia - volatile + opioid + muscle relaxant
• TIVA (Total IV Anesthesia) with propofol infusion is an excellent alternative, particularly given:
  • Propofol reduces PONV
  • Avoids all volatile-related airway irritation
  • Smooth maintenance

E. Maintaining the "SHFTO" - Prevent Sickling Triggers

• Warming: Warm IV fluids, warm blanket (Bair Hugger), keep OT warm; temperature monitoring is mandatory
• IV fluids: Normal saline or Ringer's lactate at 10 mL/kg/hr maintenance + replacement; avoid hypotonic solutions intraoperatively
• Careful positioning: No tight limb compression; avoid any position that causes venous stasis
• Tourniquet: Not relevant here, but if used elsewhere in SCD - use is controversial, generally avoided

F. Monitoring

• SpO2 (continuous, mandatory)
• Capnography (ETCO2): maintain normocarbia (35-40 mmHg); hypoventilation causes CO2 retention and acidosis, triggering sickling
• Temperature (nasopharyngeal or rectal probe)
• BP (NIBP every 5 min)
• ECG
• Urine output (Foley catheter optional for this duration, but monitor if surgery is prolonged)
• Blood glucose monitoring (pediatric patient)
• Peripheral nerve stimulator for neuromuscular blockade

G. Analgesia (Multimodal)

• Paracetamol (acetaminophen): 15 mg/kg IV infusion intraoperatively; excellent baseline analgesic, safe
• NSAIDs (Ketorolac or Diclofenac): Use with caution in SCD - NSAIDs are avoided if there is renal dysfunction (common in SCD). If renal function is normal, single-dose ketorolac 0.5 mg/kg IV is acceptable
• Opioids: Fentanyl 1-2 mcg/kg IV intraoperatively. Postoperatively, cautious morphine or tramadol with respiratory monitoring; over-sedation and hypoventilation must be avoided (triggers sickling and SpO2 drop)
• Local infiltration: Surgeon can infiltrate the palate with lidocaine + epinephrine for vasoconstriction and analgesia. Note: epinephrine should generally be used cautiously in SCD because of vasoconstrictive effects, but the small volumes used locally in palatoplasty are generally acceptable and standard surgical practice
• Bilateral pterygopalatine (sphenopalatine) nerve block may be performed by the surgeon for palatal analgesia

IV. EXTUBATION AND RECOVERY

A. Extubation Considerations

• Awake extubation is mandatory - palate repair creates a new anatomical repair that is edematous and prone to hemorrhage. The patient must have intact airway reflexes before extubation
• The throat pack must be removed and counted before extubation (check with scrub nurse, document)
• Suction the pharynx under direct vision - carefully, to avoid disrupting the repair
• Reverse neuromuscular blockade: Neostigmine 0.05 mg/kg + Glycopyrrolate 0.01 mg/kg
• Confirm TOF ratio >0.9 before extubation
• Extubate in left lateral (recovery) position to reduce aspiration risk from any blood/secretions
• Have a difficult airway trolley immediately available - re-intubation after palatoplasty can be extremely difficult because the repair distorts anatomy and is friable

B. Immediate Post-Extubation Care

• Oxygen supplementation via face mask or nasal prongs immediately - maintain SpO2 >95%
• Avoid nasal airways (nasopharyngeal airways): these are contraindicated after palatoplasty - they can disrupt the repair
• Oral airways: may also traumatize the repair - use cautiously
• Keep patient in semi-recumbent position once stable
• Monitor for:
  • Airway obstruction (soft tissue edema from the repair, especially if associated Robin sequence)
  • Primary hemorrhage (first 6 hours)
  • Laryngospasm

V. POSTOPERATIVE CARE

A. Sickle Cell Monitoring

• Continue supplemental O2 for at least 24 hours postoperatively - ACS typically occurs in the first 24-72 hours postoperatively
• Maintain IV hydration until oral intake is established (typically the day after surgery)
• Keep warm: prevent hypothermia in recovery room
• Monitor for ACS: New respiratory symptoms, chest pain, new infiltrate on CXR, falling SpO2, fever - must prompt urgent hematology review; ACS occurs in ~10% of SCD children postoperatively (Campbell-Walsh Wein Urology)
• Incentive spirometry and deep breathing exercises as soon as feasible
• Hematology review the day after surgery

B. Pain Management

• Scheduled paracetamol 15 mg/kg every 6 hours
• Judicious opioids with SpO2 monitoring
• Avoid NSAIDs if there is any concern about renal function
• If SCD pain crisis develops: regional/neuraxial analgesia (epidural) may dramatically reduce opioid requirements and improve outcome (Miller's Anesthesia)

C. Palatoplasty-Specific Postoperative Points

• Liquid diet for 2-3 weeks
• Arm restraints (Logan bow) to prevent the child from putting fingers in the mouth
• Monitor for primary hemorrhage (return to OT risk)
• Antibiotics (as per surgical team's protocol)

VI. COMPLICATIONS TO ANTICIPATE

Summary / Key Exam Points

1. Pre-op transfusion to Hb >10 g/dL (simple transfusion for intermediate surgery) - involve hematologist
2. Avoid the 5 sickling triggers: Hypoxia, Hypothermia, Dehydration, Acidosis, Stasis
3. Oral RAE tube with throat pack for shared airway; verify tube position after Boyle-Davis gag
4. NO nitrous oxide in SCD
5. Awake extubation - throat pack removal documented, left lateral position
6. Postoperative O2 for 24-48 hours; watch for ACS (first 24-72 hrs)
7. Multimodal analgesia - NSAIDs cautiously (renal function); adequate pain control reduces VOC risk
8. Temperature monitoring + warming throughout the perioperative period