G70.01

ICD-10-CM G70.01: Myasthenia Gravis With (Acute) Exacerbation

Quick reference

Element	Value
ICD-10-CM code	G70.01
Official descriptor	Myasthenia gravis with (acute) exacerbation
Synonym	Myasthenic crisis
Parent category	G70.0 - Myasthenia gravis; G70 - Myasthenia gravis and other myoneural disorders
ICD-10-CM chapter	G00-G99 (Diseases of the nervous system) → G70-G73 (Diseases of myoneural junction and muscle)
Billable	✓ Yes (terminal, reportable code)
Clinical definition	Life-threatening exacerbation of myasthenia gravis with severe generalized muscle weakness and respiratory failure requiring urgent intervention (often mechanical ventilation)
HCC status	YES - HCC-relevant in CMS-HCC models (same HCC mapping as G70.00; verify current V28 mapping)
Chronic condition	Yes (underlying MG is chronic; exacerbation is acute-on-chronic)
Typical care setting	Inpatient - ICU/critical care unit; requires intensive monitoring and intervention
Mortality risk	Historically 30-40%; modern management with mechanical ventilation has reduced mortality to ~3-8%

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Short description

G70.01 codes myasthenia gravis with acute exacerbation (also called myasthenic crisis) - a life-threatening complication characterized by severe generalized muscle weakness with respiratory failure requiring urgent hospitalization, intensive monitoring, and typically mechanical ventilation along with rapid immunomodulatory therapy (plasmapheresis or IVIG).

Use G70.01 when the patient’s myasthenia gravis has acutely decompensated to the point of requiring hospital admission (typically ICU), respiratory support, and/or acute immunotherapy (plasmapheresis/IVIG).

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Full description (clinical context)

What is myasthenic crisis?

Myasthenic crisis is the most severe and life-threatening manifestation of myasthenia gravis, occurring in 15-20% of MG patients at some point during their disease course.

Defining features:

• Severe generalized muscle weakness involving bulbar and respiratory muscles.
• Respiratory failure requiring mechanical ventilation in 67-90% of cases.
• Over 20% require intubation in the emergency department; almost 60% are intubated after ICU admission.
• Inability to protect airway due to bulbar weakness (dysphagia, weak cough, aspiration risk).
• Rapid clinical deterioration over hours to days (distinguishes from stable chronic MG).

Pathophysiology: Same autoimmune mechanism as baseline MG (antibodies against acetylcholine receptors or MuSK), but with acute worsening triggered by precipitating factors.

Common precipitants of myasthenic crisis

Infections (most common trigger - 30-40% of cases):

• Respiratory infections (pneumonia, URI, bronchitis).
• Urinary tract infections.
• Sepsis from any source.

Medications that worsen myasthenia:

• Antibiotics: Fluoroquinolones, aminoglycosides, macrolides.
• Beta-blockers (increase MG exacerbation risk 2.7-fold).
• Calcium channel blockers (felodipine, nifedipine, verapamil) - can cause respiratory failure.
• Immune checkpoint inhibitors (nivolumab, pembrolizumab) - 45% develop respiratory failure; 25-40% mortality.
• Statins - small but statistically significant increase in MG exacerbations.
• Glucocorticoids - paradoxically, 33.3% of MG patients worsen with steroids (especially high-dose or alternate-day prednisone).
• Magnesium (IV), neuromuscular blockers, lithium, antipsychotics (chlorpromazine, haloperidol, clozapine, olanzapine, quetiapine).

Surgical stress:

• Post-operative period (especially thoracic or abdominal surgery).
• Thymectomy complications.

Pregnancy and postpartum period

Abrupt medication changes:

• Sudden withdrawal or reduction of pyridostigmine.
• Non-compliance with immunosuppressants.

Cholinergic crisis (rare):

• Overdose of cholinesterase inhibitors (pyridostigmine) causing excessive ACh accumulation.
• Distinguished by increased secretions, miosis, fasciculations, diarrhea (unlike myasthenic crisis which is “dry”).

Clinical presentation of myasthenic crisis

Respiratory symptoms (MOST CRITICAL):

• Progressive dyspnea, tachypnea, shallow breathing.
• Inability to cough effectively or clear secretions.
• Hypoxemia (SpO₂ <90% on room air) or hypercapnia (PaCO₂ >50 mmHg).
• Forced vital capacity (FVC) <15-20 mL/kg or negative inspiratory force (NIF) ←20 cm H₂O = impending respiratory failure.
• Use of accessory muscles, paradoxical breathing.

Bulbar symptoms:

• Severe dysphagia (difficulty swallowing saliva, unable to take PO meds/food).
• Dysarthria (slurred speech, nasal quality).
• Weak gag reflex → aspiration risk.
• Pooling of secretions in oropharynx.

Generalized weakness:

• Severe proximal limb weakness (cannot lift arms, legs; bed-bound).
• Neck flexor weakness (head drop; unable to lift head from pillow).
• Facial weakness (expressionless face, inability to close eyes fully, weak smile).

Ocular symptoms (may be present but not always prominent in crisis):

• Ptosis (often bilateral).
• Diplopia (extraocular muscle weakness).

Distinguishing features of CRISIS:

• Rapid progression (hours to days, not weeks/months).
• Respiratory compromise requiring ICU-level care.
• Inability to perform ADLs due to severe weakness.

Diagnostic workup during myasthenic crisis

Immediate assessment (ER/ICU):

• ABG: Hypoxemia (PaO₂ <60 mmHg), hypercapnia (PaCO₂ >50 mmHg), respiratory acidosis.
• Bedside spirometry: FVC <1 L or <15-20 mL/kg = high risk for intubation.
• Negative inspiratory force (NIF): ←20 cm H₂O = respiratory muscle failure (note: NIF is less reliable than FVC).
• Chest X-ray: Rule out pneumonia, aspiration, atelectasis.

Labs to identify precipitants:

• CBC with differential: Leukocytosis (infection), anemia.
• CMP: Electrolyte abnormalities (hypokalemia worsens MG), renal function.
• Infection workup: Urinalysis, urine culture, blood cultures, respiratory cultures.
• Medication review: Identify culprit drugs.

MG-specific testing (if new diagnosis):

• Anti-AChR antibodies (draw BEFORE plasmapheresis/IVIG).
• Anti-MuSK antibodies (if AChR-negative).
• Repetitive nerve stimulation (RNS): ≥10% decrement = abnormal.
• Single-fiber EMG: Increased jitter (most sensitive test).
• Chest CT: Screen for thymoma (10-15% of MG patients).

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Coding specifics (G70.01 vs G70.00)

Code structure breakdown

Character position	Value	Meaning
1st	G	Diseases of the nervous system
2nd-3rd	70	Myasthenia gravis and other myoneural disorders
4th	.0	Myasthenia gravis
5th-6th	1	With (acute) exacerbation

When to code G70.01

Use G70.01 when:

• Myasthenic crisis with respiratory failure.
• Patient requires hospital admission (typically ICU) for acute MG exacerbation.
• Mechanical ventilation initiated due to MG-related respiratory failure.
• Acute immunotherapy (plasmapheresis or IVIG) required for severe MG exacerbation.
• Severe generalized weakness with rapid progression requiring urgent intervention.
• Bulbar weakness causing aspiration risk or inability to take PO medications.

Supporting documentation phrases:

• “Myasthenic crisis with respiratory failure.”
• “MG with acute exacerbation requiring ICU admission.”
• “Myasthenia gravis exacerbation requiring mechanical ventilation.”
• “Acute worsening of MG precipitated by [infection/medication/surgery].”

When to code G70.00 (WITHOUT exacerbation) instead

Use G70.00 when:

• MG is stable, controlled, or in chronic maintenance phase.
• Outpatient management or routine follow-up.
• No acute respiratory compromise or need for ICU-level care.
• No recent need for plasmapheresis/IVIG for acute exacerbation.

Key distinction: G70.01 = life-threatening crisis/acute hospitalization; G70.00 = stable chronic disease.

Related ICD-10 codes (same family)

ICD-10-CM	Description	When to use
G70.0	Myasthenia gravis (category)	Non-billable parent
G70.00	Myasthenia gravis without (acute) exacerbation	Stable/chronic outpatient MG
G70.01	Myasthenia gravis with (acute) exacerbation	Myasthenic crisis (THIS)
G70.1	Toxic myoneural disorders	Drug-induced NMJ disorder
G70.2	Congenital and developmental myasthenia	Congenital MG syndromes
G70.8x	Other specified myoneural disorders	Lambert-Eaton, etc.
G70.9	Myoneural disorder, unspecified	Avoid when MG confirmed
P94.0	Transient neonatal myasthenia gravis	Neonatal only (Excludes1)

Additional codes commonly paired with G70.01

Respiratory failure codes (code BOTH):

• J96.00 - Acute respiratory failure, unspecified whether with hypoxia or hypercapnia
• J96.01 - Acute respiratory failure with hypoxia
• J96.02 - Acute respiratory failure with hypercapnia
• J96.20 - Acute and chronic respiratory failure, unspecified
• Z99.11 - Dependence on ventilator status (if prolonged ventilation)

Precipitating conditions:

• J18.9 - Pneumonia, unspecified organism (if infection precipitated crisis)
• N39.0 - Urinary tract infection, site not specified
• A41.9 - Sepsis, unspecified organism
• T88.7XXA - Unspecified adverse effect of drug or medicament, initial encounter (if drug-induced)

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HCC information (risk adjustment) - CRITICAL FOR CODING

HCC status: YES - G70.01 is HCC-relevant (same as G70.00)

G70.01 myasthenia gravis with acute exacerbation maps to the SAME HCC category as G70.00 in CMS-HCC risk adjustment models.

Important HCC capture notes:

• Annual recapture required: HCC codes reset every January 1st; must be documented at least once per calendar year to maintain RAF score.
• G70.01 vs G70.00 for HCC purposes: Both map to the same HCC; however, G70.01 indicates higher severity and typically generates higher reimbursement through DRG assignment in inpatient settings rather than through differential HCC weighting.
• Inpatient encounters count for HCC capture: G70.01 coded during hospitalization DOES count toward annual HCC recapture (unlike some other acute exacerbation codes).
• Transition to outpatient G70.00: After discharge from myasthenic crisis, subsequent outpatient visits should code G70.00 (without exacerbation) unless another acute exacerbation occurs.

CMS-HCC Model V28 transition (2024-2026):

• Payment Year 2024: 67% V24 + 33% V28
• Payment Year 2025: 50% V24 + 50% V28
• Payment Year 2026: 33% V24 + 67% V28 (full V28 implementation)
• Average RAF score decreases of 5-8% expected with V28; verify current-year HCC mapping.

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Documentation requirements (work checklist)

Essential elements for G70.01

To support accurate coding, HCC capture, DRG assignment, and medical necessity:

1. Explicit diagnosis statement

   • “Myasthenic crisis” OR “Myasthenia gravis with acute exacerbation” stated in admission diagnosis or discharge summary.
   • “Respiratory failure due to myasthenic crisis” (links respiratory failure to MG cause).

2. Precipitating factor documented (if identified)

   • Infection (pneumonia, UTI, sepsis).
   • Offending medication (list specific drugs).
   • Surgical stress, pregnancy, medication non-compliance.

3. Severity indicators documented

   • Respiratory status: FVC <15-20 mL/kg, NIF ←20 cm H₂O, ABG showing hypoxemia/hypercapnia.
   • Need for mechanical ventilation (invasive or non-invasive).
   • Bulbar dysfunction: dysphagia, aspiration risk, weak gag.
   • Generalized weakness: Unable to ambulate, bed-bound, head drop.

4. Treatment rendered

   • Plasmapheresis (preferred; faster response).
   • IVIG (if PLEX contraindicated/unavailable).
   • Mechanical ventilation (document mode, settings, duration).
   • ICU admission and monitoring.
   • Immunosuppressive therapy adjustments.

5. Baseline MG history (if known)

   • Prior diagnosis confirmation (AChR/MuSK antibodies, EMG).
   • Chronic medications (pyridostigmine, prednisone, steroid-sparing agents).
   • Prior exacerbations or hospitalizations.

6. Response to treatment & disposition

   • Improvement in respiratory parameters (FVC, ABG).
   • Successful extubation (if applicable).
   • Discharge to home, rehab, or LTAC with ongoing MG management plan.

Common auditor red flags

• “Myasthenia gravis exacerbation” without specifying ACUTE → may default to G70.00; explicitly state “acute exacerbation” or “crisis.”
• G70.01 coded for stable MG patient admitted for unrelated reason → if MG didn’t cause admission and wasn’t acutely exacerbated, use G70.00.
• Respiratory failure not linked to MG → document “respiratory failure secondary to myasthenic crisis” to establish causality.
• Cholinergic crisis mistaken for myasthenic crisis → document distinguishing features (increased secretions, miosis in cholinergic vs “dry” presentation in myasthenic).
• Missing precipitant documentation → identify and code trigger (infection, drug-induced, etc.) for complete clinical picture and quality metrics.

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Associated CPT codes (common pairings)

Critical care E/M codes (ICU management)

ICU/critical care services for myasthenic crisis: [722][725]

CPT	Description	Context for G70.01
99291	Critical care, first 30-74 minutes	Primary ICU code for myasthenic crisis management
99292	Critical care, each additional 30 minutes	Add-on code for prolonged ICU care
99221-99223	Initial hospital care (day 1)	If not meeting critical care criteria initially
99231-99233	Subsequent hospital care	Once stabilized, no longer critical

Mechanical ventilation management

Ventilator management codes for respiratory failure in myasthenic crisis: [1092][1100]

CPT	Description	Clinical use	Notes
94002	Ventilation assist and management, initiation (hospital inpatient/observation, initial day)	First day of mechanical ventilation for myasthenic crisis	Requires pressure/volume preset ventilator; code once per hospitalization
94003	Ventilation assist and management, hospital inpatient/observation, each subsequent day	Daily ventilator management after initial day	Code each day patient remains ventilated
94004	Ventilation assist and management, nursing facility, per day	If transferred to SNF/LTAC on ventilator	Post-acute care setting
94005	Home ventilator management care plan oversight	Discharged home on ventilator (rare in MG)	Chronic vent dependence
31500	Intubation, endotracheal, emergency procedure	Emergency intubation in ED or bedside	Usually included in critical care time

Note: 67-90% of myasthenic crisis patients require mechanical ventilation; ventilator codes are CRITICAL for accurate billing.

Plasmapheresis (therapeutic apheresis)

Plasmapheresis is FIRST-LINE therapy for myasthenic crisis (faster response than IVIG).

CPT	Description	Clinical use	Billing notes
36514	Therapeutic apheresis; for plasma pheresis	Most common code for plasmapheresis in MG crisis	Typically 3-5 sessions over 7-14 days
36515	Therapeutic apheresis; with extracorporeal immunoadsorption and plasma reinfusion	Selective immunoadsorption (less common)	Specialized centers
36516	Therapeutic apheresis; with extracorporeal immunoadsorption, selective adsorption or selective filtration	Selective filtration techniques	Advanced modalities

Plasmapheresis procedure details:

• Mechanism: Directly removes anti-AChR antibodies from circulation.
• Response time: Improvement usually seen by 2nd or 3rd session (within few days).
• Typical protocol: 5 exchanges over 10-14 days; exchange 1-1.5 plasma volumes per session.
• Replacement fluid: Albumin or fresh frozen plasma (FFP).
• Complications: Hypocalcemia (citrate toxicity), hypotension, line infections, coagulopathy.

IVIG (intravenous immunoglobulin)

IVIG is alternative to plasmapheresis (slower onset; used when PLEX contraindicated/unavailable).

CPT	Description	Clinical use
96365	IV infusion, initial substance/drug, first hour	First hour of IVIG infusion
96366	IV infusion, each additional hour (add-on)	Additional infusion time (IVIG often takes 4-6 hours)
+96367	Additional sequential IV infusion, up to 1 hour	If multiple agents given

HCPCS codes for IVIG products:

• J1459 - Injection, immune globulin (Privigen), IV, 500 mg (report units: 500 mg = 1 unit)
• J1555 - Injection, immune globulin (Cuvitru), SC, 100 mg
• J1556 - Injection, immune globulin (Bivigam), IV, 500 mg
• J1557 - Injection, immune globulin (Gammaplex), IV, 500 mg
• J1561 - Injection, immune globulin (Gamunex-C/Gammaked), IV, 500 mg
• J1566 - Injection, immune globulin, IV, Lyophilized, 500 mg
• J1569 - Injection, immune globulin (Gammagard Liquid), IV, 500 mg

IVIG dosing for myasthenic crisis:

• Standard dose: 2 grams/kg total dose divided over 2-5 days.
• Example: 70 kg patient = 140 grams total; given as 28 grams daily × 5 days OR 70 grams daily × 2 days.
• Response time: 2-3 weeks (slower than plasmapheresis).

Respiratory diagnostic testing

CPT	Description	Use in myasthenic crisis
94010	Spirometry (FVC, FEV1)	Bedside FVC monitoring (key indicator of respiratory muscle strength)
94200	Maximum breathing capacity (MBC)	Respiratory muscle strength assessment
94060	Bronchodilation responsiveness	Usually not needed in MG (not obstructive disease)
82803	Blood gases (arterial), any combination	ABG monitoring for hypoxemia/hypercapnia
71045-71048	Chest X-ray	Rule out pneumonia, aspiration, atelectasis

EMG/nerve conduction studies (diagnostic)

CPT	Description	MG workup
95937	Neuromuscular junction testing (repetitive stimulation)	RNS showing ≥10% decrement = diagnostic
95860-95864	Needle EMG (1-4 extremities)	Single-fiber EMG shows increased jitter
95885	Needle EMG, limited	Targeted EMG for MG evaluation
95857	Tensilon test (edrophonium challenge)	Less common now; diagnostic confirmation

Serologic testing

CPT	Description	Clinical use
86255	Antibody; acetylcholine receptor (AChR)	Draw BEFORE plasmapheresis/IVIG
86336	Antibody; muscle-specific kinase (MuSK)	For AChR-negative MG

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Treatment overview (coding context)

Immediate stabilization (Emergency Department → ICU)

Airway & breathing:

1. Assess respiratory status:

   • FVC, NIF, ABG, clinical signs of respiratory distress.
   • Intubation criteria: FVC <15-20 mL/kg, NIF ←20 cm H₂O, hypoxemia, hypercapnia, inability to protect airway.

2. Mechanical ventilation:

   • Invasive: Endotracheal intubation + positive pressure ventilation (most common).
   • Non-invasive (BiPAP/CPAP): May be attempted in select patients to avoid intubation, but ~70% still require intubation.
   • Ventilator settings: Pressure control or volume control modes; titrate FiO₂ and PEEP to maintain SpO₂ >92%.

3. Hold pyridostigmine once intubated → reduces airway secretions (cholinergic effects worsen secretion management). [1047]

Acute immunotherapy (PRIMARY TREATMENT)

Plasmapheresis (PLEX) - FIRST-LINE for severe myasthenic crisis:

• Preferred because it works faster (improvement by 2nd-3rd session = few days).
• Mechanism: Directly removes anti-AChR antibodies.
• Protocol: 5 exchanges over 10-14 days; 1-1.5 plasma volumes per exchange.
• Advantages: Rapid efficacy (critical for intubated patients to minimize ventilator days and VAP risk).
• Contraindications: Hemodynamic instability, coagulopathy, poor vascular access.

IVIG - SECOND-LINE or alternative:

• Used when PLEX contraindicated or unavailable.
• Dose: 2 grams/kg total over 2-5 days.
• Response time: 2-3 weeks (slower than PLEX).
• Advantages: Easier to administer; fewer complications; no need for vascular access team.
• Disadvantages: Delayed onset; may be less effective in MuSK+ MG.

Recent comparative studies:

• PLEX associated with faster clinical improvement and shorter hospitalization compared to IVIG in myasthenic crisis.
• However, IVIG may have fewer complications and lower treatment discontinuation rates.
• PLEX recommended for more severe cases; IVIG for milder exacerbations or when PLEX unavailable.

Immunosuppressive therapy (CHRONIC MANAGEMENT)

Continue or initiate during hospitalization:

• Corticosteroids: Prednisone 1 mg/kg/day (start LOW if not already on steroids to avoid steroid-induced worsening).
• Steroid-sparing agents: Azathioprine, mycophenolate mofetil, tacrolimus, cyclosporine.
• Biologics: Rituximab for refractory cases; eculizumab (Soliris), efgartigimod (Vyvgart), nipocalimab (Imaavy - FDA approved April 2025).

Identify and treat precipitants

• Infection: Broad-spectrum antibiotics for pneumonia/sepsis; source control.
• Medication withdrawal: Discontinue offending drugs (beta-blockers, fluoroquinolones, etc.).
• Medication optimization: Avoid drugs that worsen MG.

Supportive care

• DVT prophylaxis: SCDs, heparin (immobilized ICU patient).
• Stress ulcer prophylaxis: PPI or H2-blocker.
• Nutrition: Enteral feeding via NG/OG tube if intubated or severe dysphagia.
• Physical therapy: Early mobilization once stable to prevent ICU-acquired weakness.

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Sample ICD-10 combinations (work scenarios)

Scenario 1: Myasthenic crisis with respiratory failure requiring intubation

ICD-10-CM codes:

• G70.01 - Myasthenia gravis with (acute) exacerbation (primary diagnosis)
• J96.01 - Acute respiratory failure with hypoxia
• J18.9 - Pneumonia, unspecified organism (if pneumonia precipitated crisis)
• Z99.11 - Dependence on ventilator status (if prolonged ventilation >96 hours)

CPT:

• 99291 + 99292 × [units] - Critical care
• 94002 - Ventilation assist, initial day
• 94003 - Ventilation assist, subsequent days (×[number of days])
• 36514 - Plasmapheresis (×[number of sessions])

DRG: 56 - Degenerative nervous system disorders with MCC (if MCC criteria met)

Rationale: G70.01 as primary captures acute crisis; J96.01 documents respiratory failure cause; pneumonia coded as precipitant; ventilator and PLEX codes capture major interventions.

Scenario 2: Myasthenic crisis precipitated by fluoroquinolone antibiotic

ICD-10-CM codes:

• G70.01 - Myasthenia gravis with (acute) exacerbation
• T36.8X5A - Adverse effect of other systemic antibiotics, initial encounter (fluoroquinolone)
• J96.00 - Acute respiratory failure, unspecified
• Z87.2 - Personal history of diseases of the endocrine, nutritional and metabolic systems (if applicable)

CPT:

• 99291 + 99292 - Critical care
• 96365 + 96366 × [hours] - IVIG infusion
• J1569 × [units] - Gammagard Liquid (calculate units: dose in mg ÷ 500 = units)

Rationale: Drug-induced exacerbation documented with adverse effect code; IVIG used instead of PLEX.

Scenario 3: Known MG patient admitted to ICU in crisis, successfully extubated after PLEX

ICD-10-CM codes:

• G70.01 - Myasthenia gravis with (acute) exacerbation
• J96.02 - Acute respiratory failure with hypercapnia
• Z87.891 - Personal history of nicotine dependence (if applicable)

CPT:

• 99291 + 99292 × [units] - Critical care (multiple days)
• 94002 + 94003 × 3 - Ventilator management (intubated 4 days total)
• 36514 × 5 - Plasmapheresis (5 sessions)
• 99233 - Subsequent hospital care, high complexity (post-extubation floor care)

Rationale: Patient intubated for respiratory failure due to myasthenic crisis, received plasmapheresis, improved and extubated, transitioned to floor care.

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Sample documentation (hospital admission note template)

Admission Date: [Date]
Admission Diagnosis: Myasthenic crisis with acute respiratory failure.

Chief Complaint: Severe muscle weakness and difficulty breathing.

HPI: [Age]-year-old [male/female] with history of myasthenia gravis (diagnosed [date]; AChR antibody-positive / MuSK-positive / seronegative) on chronic pyridostigmine and prednisone presents with acute worsening of generalized muscle weakness over the past 2-3 days progressing to respiratory distress. Patient reports progressive dysphagia, dysarthria, diplopia, and limbs weakness preventing ambulation. Unable to swallow medications or PO intake. Dyspnea at rest. [Precipitant: developed URI symptoms 5 days ago / started levofloxacin 3 days ago / underwent [surgical procedure] 1 week ago].

Past Medical History:

• Myasthenia gravis (AChR antibody-positive; generalized)
• Status post thymectomy [date] (if applicable)
• [Other chronic conditions]

Current Medications:

• Pyridostigmine (Mestinon) [dose] PO q6h
• Prednisone [dose] PO daily
• [Other immunosuppressants]

Exam on Admission (Emergency Department):

• General: Severe distress, using accessory muscles, unable to speak full sentences.
• Vital Signs: RR 32, SpO₂ 88% on RA → 92% on 4L NC; HR 110, BP 145/90
• Ocular: Bilateral ptosis, limited EOM, diplopia
• Bulbar: Severe dysarthria, weak gag reflex, pooling of secretions, dysphagia (unable to swallow water)
• Motor: Severe proximal weakness bilaterally (0/5 shoulder abduction, 1/5 hip flexion); neck flexor weakness (unable to lift head); facial weakness
• Respiratory: Shallow breathing, paradoxical abdominal movement, poor cough

Labs:

• ABG (on 4L NC): pH 7.32, PaCO₂ 52 mmHg, PaO₂ 68 mmHg (hypercapnic respiratory failure)
• Bedside spirometry: FVC 0.8 L (predicted 3.5 L) = 23% predicted → <15-20 mL/kg = impending respiratory failure
• NIF: -15 cm H₂O (normal ←60) = severe respiratory muscle weakness
• CBC: WBC 14,000 (left shift), Hgb 13.5
• CMP: K 3.2, Cr 0.9, otherwise normal
• Chest X-ray: Right lower lobe infiltrate (pneumonia)
• Anti-AChR antibodies: Positive (previously confirmed)

Emergency Department Course:

• Diagnosis: Myasthenic crisis precipitated by pneumonia.
• Intubated for respiratory failure (RSI with rocuronium + etomidate).
• Admitted to Medical ICU for mechanical ventilation, plasmapheresis, and treatment of precipitating pneumonia.

ICU Management Plan:

• Mechanical ventilation: Pressure control mode; FiO₂ 40%, PEEP 5, target SpO₂ >92%.
• Plasmapheresis: 5 sessions over 10-14 days (CPT 36514). Central line placed for apheresis access.
• Hold pyridostigmine while intubated (reduce secretions).
• Continue prednisone 60 mg daily via NG tube.
• Antibiotics: Ceftriaxone + azithromycin for community-acquired pneumonia.
• Avoid: Beta-blockers, fluoroquinolones, aminoglycosides, magnesium.
• Monitor: Daily FVC (goal >20 mL/kg for extubation readiness), ABGs, clinical strength.
• DVT prophylaxis: SCDs + heparin 5000 units SQ q8h.
• Stress ulcer prophylaxis: Pantoprazole 40 mg IV daily.

Admission Diagnoses:

1. Myasthenic crisis (G70.01) - myasthenia gravis with acute exacerbation
2. Acute hypercapnic respiratory failure (J96.02) due to myasthenic crisis
3. Community-acquired pneumonia, right lower lobe (J18.9) - precipitant
4. Hypokalemia (E87.6) - likely contributing to weakness

Prognosis: Guarded; ~70% of myasthenic crisis patients require intubation; mortality 3-8% with modern ICU care. Expected ICU stay 7-14 days pending response to plasmapheresis.

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Billing & compliance pearls

• G70.01 is HCC-relevant but primarily drives DRG reimbursement in inpatient settings rather than differential HCC weighting (same HCC as G70.00).
• Principal diagnosis = G70.01 for myasthenic crisis admissions; respiratory failure (J96.x) is secondary (MG caused the respiratory failure).
• Plasmapheresis (36514) has high RVU - ensure all sessions documented and billed separately.
• Critical care time (99291/99292) is separately billable from procedures (plasmapheresis, ventilator management) performed during same day.
• Ventilator management (94002/94003) is per-day billing - code 94002 on day 1 of intubation, then 94003 each subsequent day until extubation.
• Document precipitant - infection, drug-induced, surgical stress - to support medical necessity and quality metrics.
• Transition to G70.00 after discharge - outpatient follow-up visits post-crisis should code G70.00 (without exacerbation) unless another acute crisis occurs.
• IVIG units calculation - dose in mg ÷ 500 = number of HCPCS units for J-codes; document exact product used.

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Key sources (compact format)

[1047]: Myasthenia gravis pathophysiology, autoimmune mechanism, precipitants (infections, drugs including beta-blockers/fluoroquinolones/checkpoint inhibitors/statins/steroids/calcium channel blockers), plasmapheresis/IVIG indications, mechanical ventilation, mortality with checkpoint inhibitors (45% respiratory failure, 25-40% death), steroid-induced worsening (33.3%)
[1083]: ECGWaves G70.01 classification under G70-G73 diseases of myoneural junction
[1084]: AAPC G70.01 official descriptor “Myasthenia gravis with (acute) exacerbation,” synonym “Myasthenia gravis in crisis,” Excludes1 notes
[1086]: GenHealth.ai G70.01 related codes, HCPCS codes for neostigmine, clinical context
[1087]: IMAAVY (nipocalimab) billing guide ICD-10-CM G70.00/G70.01, J9256 HCPCS code, UB-04 form instructions
[1088]: PMC myasthenic crisis clinical/economic outcomes, plasmapheresis vs IVIG effectiveness (PLEX faster improvement, shorter hospitalization; IVIG fewer complications), treatment selection based on severity
[1090]: EMCrit myasthenia crisis management protocol, PLEX preferred over IVIG (faster response), FVC monitoring (DO NOT wake patient), ice pack test, monitoring parameters, avoid pyridostigmine when intubated, rituximab for refractory cases
[1097]: PMC myasthenic crisis respiratory management, 67-90% require intubation, 20% intubated in ED/60% after ICU admission, mortality 3-8%, NIV may avoid intubation in select patients
[1082]: Plasmapheresis mechanism, removal of autoantibodies, immunosuppressants (cyclophosphamide/cyclosporine/mycophenolate/prednisone/rituximab), citrate-induced hypocalcemia (Chvostek/Trousseau signs)
[1092]: Mechanical ventilation indications (myasthenia gravis listed), positive-pressure ventilation, complications (volutrauma/barotrauma/VAP), weaning criteria
[1098]: GenHealth.ai CPT 36514 therapeutic apheresis for plasma pheresis, HCPCS codes for platelets/plasma products
[1100]: GenHealth.ai CPT 94003 ventilation assist management subsequent day, pressure/volume preset ventilators, risks (VAP, barotrauma, oxygen toxicity), monitoring/weaning
[1068]: HCC Institute risk adjustment factors, CMS-HCC model transition 2024-2026
[1069]: Wolters Kluwer CMS-HCC V28 RAF score impact, model structure changes
[1071]: RAAPID CMS-HCC V28 full list, 115 HCC categories, 3-year transition blending (67% V24 + 33% V28 in 2024), -3.12% MA risk score impact, $11B Medicare savings
[1095]: CMS risk adjustment information, model diagnosis codes
[1099]: Keebler Health HCC V28 changes, 5-8% RAF score decreases, ICD-10 mapping, code consolidation
[722]: HCPCS system (Level I = CPT, Level II = HCPCS alphanumeric codes)
[725]: CPT code types (Category I/II/III), medicine codes 90281-99607
[1054]: Coding Billing Solutions G70.00 billable/specific code, reimbursement purposes
[1080]: Congenital myasthenic syndrome treatment (3,4-diaminopyridine, quinidine, fluoxetine)
[1101]: AAPC forum plasma exchange discussion, 36514 for plasma pheresis with albumin/FFP reinfusion