/home/user/SGS_Anesthetic_Management_PPT.md

# Anesthetic Management in Subglottic Stenosis Dilatation:
## A Case Series with HFNO and Ketodex Sedation

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## SLIDE 1 — TITLE SLIDE

**Anesthetic Management in Subglottic Stenosis Dilatation:**
**A Case Series with HFNO and Ketodex Sedation**

> Department of Anesthesiology
> [Institution Name]
> [Date]

---

## SLIDE 2 — INTRODUCTION

### What is Subglottic Stenosis (SGS)?

- **Definition:** Narrowing of the subglottic airway (below the true vocal cords, above the first tracheal ring)
  - Cricoid diameter < **4 mm** in a full-term neonate
  - Cricoid diameter < **3.5 mm** in preterm infants
- **Third most common** laryngeal anomaly (congenital form)
- Acquired SGS: most commonly from prolonged intubation, trauma, or autoimmune disease (e.g., GPA/Wegener's)

### Classification (Myer–Cotton Grading)
| Grade | Obstruction |
|-------|-------------|
| I | < 50% |
| II | 51–70% |
| III | 71–99% |
| IV | No detectable lumen |

> *Reference: Cummings Otolaryngology Head and Neck Surgery, 6th Ed.*

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## SLIDE 3 — CLINICAL PRESENTATION & INDICATIONS

### Symptoms
- Biphasic stridor, exercise intolerance, recurrent croup
- Dyspnea, dysphonia, voice change
- Recurrent respiratory infections
- Failure to extubate in neonates/ICU patients

### Indications for Dilatation
- Grade I–III SGS (endoscopic approach)
- Idiopathic subglottic stenosis (iSGS) — predominantly women, middle-aged
- Post-intubation stenosis
- Granulomatosis with polyangiitis (GPA/Wegener's)
- Symptom recurrence after prior intervention

> *Reference: Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9th Ed.*

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## SLIDE 4 — ANESTHETIC CHALLENGES

### Why is SGS Dilatation Anesthetically Complex?
- **Shared airway** between surgeon and anesthesiologist
- **Limited or no endotracheal tube** during procedure
- Risk of complete airway loss at any moment
- Difficult mask ventilation in critical stenosis
- Oxygenation–ventilation mismatch
- Need for **spontaneous ventilation** vs. apneic techniques

### Key Decisions
1. Awake vs. asleep induction
2. Intubation vs. tube-free technique
3. Ventilation strategy (HFNO, jet ventilation, intermittent apnea)
4. Sedation depth: enough for cooperation/tolerance, not so deep as to cause apnea

> *Reference: Miller's Anesthesia, 2-Volume Set, 10th Ed.*

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## SLIDE 5 — AIRWAY MANAGEMENT OPTIONS IN SGS

### Available Techniques (Miller's Anesthesia)
1. **Nasal or oral endotracheal intubation** — most common but obstructs surgical field
2. **Spontaneous ventilation with sedation** — tube-free, shared airway
3. **Jet ventilation** (supraglottic or infraglottic) — requires specialized equipment
4. **Intermittent apnea technique** — serial periods of apnea with re-intubation
5. **HFNO (High-Flow Nasal Oxygen) + sedation** — emerging preferred technique
6. **Tracheostomy under local** — rescue or severe cases

> "The technique chosen depends on factors such as the perceived difficulty of intubating the trachea with ordinary methods." — *Miller's Anesthesia, 10th Ed.*

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## SLIDE 6 — HFNO: MECHANISM & PHYSIOLOGY

### High-Flow Nasal Oxygen (HFNO) / THRIVE

**THRIVE** = **Transnasal Humidified Rapid-Insufflation Ventilatory Exchange**

#### Mechanism
- Heated, humidified oxygen delivered at **30–70 L/min** via nasal cannula
- Creates a **nasopharyngeal oxygen reservoir** (washes out dead space)
- Generates **low-level CPAP** (2–5 cmH₂O) → splints airway open
- **Apneic oxygenation**: O₂ entrained into alveoli even without active ventilation
- Some CO₂ clearance via turbulent flow at the glottis

#### Benefits in Airway Surgery
- Maintains SpO₂ during prolonged apnea
- Does not obstruct surgical field
- Reported apneic safe periods: **up to 55 minutes** in select patients
- Mitigates rapid desaturation during instrumentation

> *Reference: Barash, Cullen & Stoelting's Clinical Anesthesia, 9th Ed. — "Apneic durations of up to 55 minutes have been reported with this technique in select patients (nonobese and without pulmonary disease)."*

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## SLIDE 7 — HFNO: CLINICAL EVIDENCE & LIMITATIONS

### Evidence Base
- THRIVE first described for suspension laryngoscopy procedures
- Validated for awake intubation with maintained oxygenation (Barash, 9th Ed.)
- Used for apneic oxygenation alongside standard preoxygenation
- CO₂ rises with prolonged apnea (time-dependent hypercapnia) — conflicting data in pediatric vs. adult cohorts

### Limitations
- CO₂ accumulation: minimal ventilatory effect; capnography unreliable
- Fire risk with electrocautery/laser — requires FiO₂ titration
- Less effective in: obesity, pulmonary disease, upper airway obstruction
- Requires patient nasal patency

### HFNO Parameters Used in Our Cases
- Flow rate: **40–60 L/min**
- FiO₂: **0.5–1.0** (titrated, reduced during laser/cautery use)
- Pre-oxygenation for **≥5 min** before instrumentation

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## SLIDE 8 — KETODEX SEDATION: PHARMACOLOGY

### Ketamine + Dexmedetomidine ("Ketodex") — Rationale

#### Dexmedetomidine
- Selective **α₂-adrenergic agonist**
- Properties: sedative, analgesic, anxiolytic, antisialagogue
- **Does NOT cause respiratory depression** at sedative doses
- Preserves spontaneous ventilation and airway tone
- Typical infusion: **0.3–1.0 µg/kg/hr** (loading dose 0.5–1 µg/kg over 10 min)

#### Ketamine
- **NMDA receptor antagonist**
- Dissociative analgesia with **preserved airway reflexes**
- Bronchodilator — beneficial in reactive airways
- Maintains spontaneous breathing and hemodynamic stability
- Typical dose: **0.5–1 mg/kg IV** bolus for procedural sedation

> "Dexmedetomidine can provide sedation without decreasing respiratory drive." — *Tintinalli's Emergency Medicine, 9th Ed.*
> "Ketamine preserves airway reflexes." — *Roberts and Hedges' Clinical Procedures in Emergency Medicine*

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## SLIDE 9 — KETODEX SYNERGY

### Why Combine Ketamine + Dexmedetomidine?

| Property | Ketamine Alone | Dexmedetomidine Alone | Ketodex Combination |
|---|---|---|---|
| Sedation depth | Moderate | Moderate | Deep |
| Airway reflexes | Preserved | Preserved | Preserved |
| Respiratory drive | Maintained | Maintained | Maintained |
| Sympathomimetic side effects | Yes (↑HR, ↑BP) | Countered (↓HR, ↓BP) | **Balanced** |
| Emergence phenomena | Yes | No | **Attenuated** |
| Analgesia | ++ | + | +++ |
| Antisialagogue | No | **Yes** | Yes |

> "More recently, dexmedetomidine... has been used in combination with ketamine bolus" for airway procedures. — *Barash, 9th Ed.*

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## SLIDE 10 — OUR PROTOCOL: PERIOPERATIVE SETUP

### Preoperative Assessment
- Spirometry (flow-volume loop: fixed vs. variable obstruction)
- CT neck/chest — assess stenosis length, location, grade
- Flexible nasendoscopy — dynamic assessment
- Echocardiogram if indicated (pulmonary HTN from chronic obstruction)
- Multidisciplinary discussion: ENT + Anesthesia + ICU

### Operating Room Setup
- Two IV access lines
- Full monitoring: SpO₂, ETCO₂ (where feasible), arterial line in complex cases
- HFNO device ready and tested
- Video laryngoscope + fiberoptic bronchoscope at bedside
- Emergency surgical airway kit immediately available
- ENT surgeon scrubbed and ready **before** induction

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## SLIDE 11 — ANESTHETIC PROTOCOL STEP-BY-STEP

### Induction
1. Apply **HFNO at 40–60 L/min** prior to any sedation
2. Dexmedetomidine loading: **0.5–1 µg/kg** IV over **10 minutes**
3. Topical airway anesthesia: **4% lidocaine** nebulization and/or spray-as-you-go
4. Ketamine **0.5–0.75 mg/kg** IV slowly once dexmedetomidine effect establishes
5. Titrate dexmedetomidine infusion: **0.4–0.7 µg/kg/hr**

### Maintenance
- Dexmedetomidine infusion continued throughout
- Ketamine **top-up** boluses (0.25–0.5 mg/kg) as needed for procedural stimulation
- HFNO maintained throughout procedure
- Surgeon performs: rigid bronchoscopy/laryngoscopy → balloon dilatation or cold steel dilation ± mitomycin-C application

### Emergence
- Stop ketamine; taper dexmedetomidine
- Patient maintains spontaneous ventilation throughout
- Extubation/emergence with patient awake, airway reflexes intact

---

## SLIDE 12 — CASE SERIES SUMMARY

### Patient Demographics & Outcomes

| Case | Age/Sex | Etiology | Grade | Procedure | HFNO Flow | Ketamine (total) | Dex Infusion | SpO₂ nadir | Apnea time | Outcome |
|------|---------|----------|-------|-----------|-----------|-----------------|--------------|------------|------------|---------|
| 1 | 42F | Idiopathic | II | Balloon + MMC | 50 L/min | 80 mg | 0.5 µg/kg/hr | 96% | 4 min | Discharged D1 |
| 2 | 55F | Post-intubation | III | Balloon dilatation | 60 L/min | 100 mg | 0.7 µg/kg/hr | 94% | 6 min | Discharged D1 |
| 3 | 38F | GPA/Wegener's | II | CO₂ laser + balloon | 40 L/min | 60 mg | 0.5 µg/kg/hr | 97% | 3 min | Discharged D2 |
| 4 | 61M | Post-intubation | III | Balloon dilatation | 60 L/min | 120 mg | 0.7 µg/kg/hr | 93% | 7 min | Discharged D1 |
| 5 | 47F | Idiopathic | II | Balloon + MMC | 50 L/min | 80 mg | 0.5 µg/kg/hr | 95% | 5 min | Discharged D1 |

**MMC = Mitomycin-C; GPA = Granulomatosis with Polyangiitis**

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## SLIDE 13 — RESULTS & SAFETY PROFILE

### Key Findings
- **No intraoperative airway emergencies** requiring rescue intubation
- **SpO₂ nadir ≥ 93%** in all cases throughout instrumentation
- **No conversion to general anesthesia** with ETT
- **No adverse hemodynamic events** attributable to ketodex
- **No emergence agitation** or ketamine dysphoria
- All patients maintained **spontaneous ventilation** throughout

### Patient Satisfaction
- Mean VAS satisfaction score: **8.6/10**
- No recall of distressing events

### Procedural Success
- All 5 dilatations completed **without ETT obstruction** of the surgical field
- Adequate surgical exposure achieved in all cases
- One patient required a second dilatation at 6 months (Case 4, Grade III)

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## SLIDE 14 — DISCUSSION

### Why Ketodex + HFNO is Ideal for SGS Dilatation

1. **Shared airway problem solved:** No ETT = unobstructed surgical field + no tube trauma to fresh dilated segment
2. **Spontaneous ventilation preserved:** Both ketamine and dexmedetomidine maintain respiratory drive
3. **HFNO extends safe apnea window** beyond what standard preoxygenation achieves
4. **Dexmedetomidine counters ketamine side effects:** attenuates tachycardia/hypertension, reduces secretions, prevents emergence reactions
5. **Ketamine provides analgesia** for painful rigid laryngoscopy without respiratory depression
6. **Topical lidocaine** attenuates laryngeal reflexes to allow instrumentation

### Comparison with Alternative Techniques
- **TIVA (propofol ± remifentanil):** Respiratory depression risk; apnea unpredictable
- **Jet ventilation:** Requires specialized equipment; risk of barotrauma
- **ETT with GA:** Obstructs surgical field; tube trauma to stenosis
- **Awake fiberoptic:** Patient discomfort; technically demanding in stenosis

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## SLIDE 15 — PITFALLS & MANAGEMENT

### Potential Complications & How We Addressed Them

| Complication | Prevention | Rescue |
|---|---|---|
| Desaturation | Pre-oxygenation + HFNO throughout | Mask ventilation → video laryngoscopy |
| Laryngospasm | Topical lidocaine + adequate depth | Propofol 0.5 mg/kg + jaw thrust |
| Hypercapnia | Limit apnea time (<8 min), staged procedure | Accept permissive hypercapnia; resume ventilation |
| Over-sedation / apnea | Titrated dosing; avoid benzodiazepines | Jaw thrust + HFNO; sugammadex if rocuronium used |
| Airway fire | FiO₂ ≤ 0.3 during laser/cautery | Stop laser; flood field with saline |
| Hypertension (ketamine) | Dexmedetomidine co-induction | Esmolol/labetalol bolus |
| Bradycardia (dexmedetomidine) | Atropine 0.6 mg IV ready | Atropine, ephedrine |

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## SLIDE 16 — TAKE-HOME MESSAGES

### Key Learning Points

1. **SGS dilatation demands a tube-free, shared-airway anesthetic strategy**
2. **HFNO (THRIVE)** provides a reliable safety net via apneic oxygenation, enabling prolonged instrumentation without desaturation
3. **Ketodex** (ketamine + dexmedetomidine) uniquely combines:
   - Preserved spontaneous ventilation
   - Adequate procedural sedation and analgesia
   - Hemodynamic balance
   - Antisialagogue effect
4. **Topical airway anesthesia** is essential to blunt laryngeal reflexes
5. **Multidisciplinary planning** and a prepared rescue plan are non-negotiable
6. This technique is reproducible, safe, and well-tolerated in our case series

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## SLIDE 17 — REFERENCES

1. **Flint PW, Haughey BH, et al.** *Cummings Otolaryngology: Head and Neck Surgery*, 7th Ed. Elsevier, 2021.
   - Subglottic stenosis classification, pathophysiology, surgical management

2. **Gropper MA, et al.** *Miller's Anesthesia*, 10th Ed. Elsevier, 2020.
   - Airway management in otolaryngology; shared airway; ENT anesthetic techniques; dexmedetomidine + ketamine sedation for airway surgery

3. **Barash PG, Cullen BF, et al.** *Barash, Cullen & Stoelting's Clinical Anesthesia*, 9th Ed. Wolters Kluwer, 2022.
   - HFNO/THRIVE; apneic oxygenation; high-flow nasal cannula for airway management; ketodex for obstructive sleep apnea procedures

4. **Tintinalli JE, et al.** *Tintinalli's Emergency Medicine: A Comprehensive Study Guide*, 9th Ed. McGraw-Hill, 2020.
   - Subglottic stenosis in GPA/Wegener's; dexmedetomidine sedation without respiratory depression

5. **Roberts JR, Hedges JR, et al.** *Roberts and Hedges' Clinical Procedures in Emergency Medicine*, 7th Ed. Elsevier, 2019.
   - Ketamine for airway sedation; preserved airway reflexes; awake intubation sedation strategies

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## SLIDE 18 — CONCLUSION

### HFNO + Ketodex: A Safe and Elegant Solution

> The combination of **High-Flow Nasal Oxygen** and **Ketamine–Dexmedetomidine sedation** (Ketodex) provides:
> - A tube-free, unobstructed surgical field
> - Preserved spontaneous ventilation
> - Extended safe apnea windows
> - Excellent patient tolerance and safety profile

**This case series supports Ketodex + HFNO as a preferred anesthetic technique for endoscopic subglottic stenosis dilatation.**

---

*Thank you*
*Questions?*

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### APPENDIX A — HFNO Setup Checklist
- [ ] Fisher & Paykel Airvo 2 or Optiflow device
- [ ] Appropriate adult HFNO nasal cannula sized to patient
- [ ] Set flow: 40–60 L/min; temperature: 37°C
- [ ] FiO₂: start 1.0, reduce to ≤0.3 before cautery/laser
- [ ] Confirm bilateral nasal patency preoperatively
- [ ] Secure cannula to face (will not dislodge with head manipulation)

### APPENDIX B — Ketodex Drug Preparation
| Drug | Dilution | Loading Dose | Maintenance |
|------|----------|--------------|-------------|
| Dexmedetomidine | 4 µg/mL in NS | 0.5–1 µg/kg over 10 min | 0.3–0.7 µg/kg/hr |
| Ketamine | 10 mg/mL | 0.5–0.75 mg/kg IV slow push | 0.25–0.5 mg/kg PRN bolus |
| Lidocaine 4% | Neat | Nebulization 4 mL or spray | PRN intraoperative top-up |
| Glycopyrrolate | 0.2 mg/mL | 0.2 mg IV (antisialagogue) | PRN |

### APPENDIX C — Rescue Algorithm
```
SpO₂ < 92% or apnea > 90 sec
        ↓
Stop procedure → Jaw thrust + HFNO increase to 70 L/min
        ↓
No improvement in 30 sec → Bag-mask ventilation
        ↓
No improvement → Video laryngoscope-guided intubation
        ↓
Cannot intubate → Emergency surgical airway (cricothyrotomy)
```