Pulmonary

Peter P. Moschovis

Lael M. Yonker

Elizabeth C. Parsons

Benjamin A. Nelson

Efraim Sadot

Christina V. Scirica

Kenan Haver

Natan Noviski

Pulmonary Function Tests

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Abbreviations

FVC: Max volume expired during forced expiratory maneuver

FEV₁: Volume expired in 1st sec after max inspiration

FEV₁/FVC: Measure of airflow obstruction

FEF_25–75: Mid flow-rate of FVC (reflects small airways obstruction, less effort-dependent, but highly variable)

DLCO: Diffusion capacity of CO

PEFR: Peak expiratory flow rate

Obstructive lung disease: Asthma, protracted bronchitis, early cystic fibrosis

Restrictive lung disease: Thoracic (ILD, pneumothorax, edema, consolidation, fibrosis) and extrathoracic (obesity, resp muscle weakness, thoracic deformities, pleural disease)

Basic Spirometry with Lung Volumes

Indications: Eval (1) if dysfxn, if obstructive, restrictive, or mixed & location & degree, (2) progression of known dz, (3) resp to bronchodilators
Relative contraindications: Hemoptysis of unknown origin, PTX, recent eye surgery (increased IOP during forced exp maneuvers)

Parameter	Normal	Obstructive	Restrictive
FVC	≥80% pred or LLN (Lower Limit Nml)	↔↓ bronchodilator responsive: ↑12% or 0.2L	↓↓
FEV1	≥80% pred or LLN	↓↓ bronchodilator responsive: ↑12% or 0.2L	↔↓
FEV1/FVC	85% for 8–19 yo	↓↓	↔↓
RV		↑ ↑	↓↓ (early)
TLC		↑ ↑	↓↓ (late)
RV/TLC		↑ ↑	↓↓

Diffusion Capacity

Indications: Eval for parenchymal dz (DLCO measures “efficiency” of gas exchange)
DLCO dependent on TLC and Hgb; any process that ↓ them will ↓ DLCO as well
↓ DLCO can be 2/2: Parenchymal or pulm vascular dz, extrapulm restriction (lung resection, scoliosis), anemia (adjust for Hgb mathematically), tachycardia

Bronchial Provocation Testing

Indication: Suspect asthma, but spirometry normal
Procedure: Spirometry before/after progressive doses methacholine, histamine, exercise, mannitol, or hyperventilation/cold air
Positive test: FEV₁ reduced 20% after challenge

Respiratory Muscle Strength

Indication: Rule out muscle weakness as a cause for respiratory insufficiency
Procedure: Pt breathes against shutter valve, measure max inspiratory pressure (MIP) and max expiratory pressure (MEP); perform at least 10× for consistency
Implications: Compare to age norms, MEP <50 cm H₂O suggests insuff cough to clear secretions; MIP <-80 and MEP >+80 cm H₂O r/o signif weakness (adults) Thorax 1984;39:535–538

Common Respiratory Complaints

Wheezing

Acute: Asthma, bronchiolitis, anaphylaxis, toxic inhalation, medication induced (β-blocker, ASA, indomethacin), aspiration
Chronic: Asthma, GERD, protracted bronchitis, asthma, CHF, vascular rings, tracheomalacia
Workup: Consider CXR if suspect asthma or aspiration, PFTs, pH probe, fluoroscopy for tracheomalacia or foreign body

Stridor

Inspiratory: Most common, extrathoracic origin
- Laryngeal (most common): Laryngomalacia (most common chronic cause), croup (most common acute cause), laryngeal web/cyst, epiglottitis, vocal cord paralysis, subglottic stenosis (postintubation or congenital), foreign body, tumor (subglottic hemangioma or laryngeal papilloma), angioedema, traumatic intubation, laryngospasm (hypocalcemic tetany), psychogenic
- Nasopharyngeal: Choanal atresia, lingual thyroid or thyroglossal cyst, macroglossia or micrognathia, hypertrophic tonsils/adenoids (h/o snoring), RP or peritonsillar abscess (drooling, “tripod”-ing)
- Tracheal: Tracheomalacia, bacterial tracheitis, external compression (cystic hygroma), TEF (worsens w/feeds)
Expiratory: Less common, intrathoracic; mimics asthma, but tracheal/bronchial
- Tracheomalacia, bronchomalacia, vascular rings, extrinsic compression, psych
Diagnostic clues:
- Worse asleep → pharyngeal (tonsils, adenoids) origin
- Worse awake/with agitation → laryngeal, tracheal or bronchial origin
- Worse supine → laryngo/tracheomalacia, micrognathia, macroglossia
- Acute: Infxn or foreign body; psychogenic (often w/o distress, neck flexed)
Workup: AP/lateral neck films to assess upper airway anatomy, chest film if suspect foreign body aspiration, direct bronch for persistent sx or foreign body, CT to r/o extrinsic compression, barium swallow to r/o vascular compression or GERD
Treatment: See ED section for acute treatment; treat underlying cause

Cough

Acute: URI, PNA, pneumonia, aspiration, PE
Chronic: Postnasal drip, GERD, bronchitis, TB, bronchiectasis, cough-variant asthma, toxic exposure (cigarette smoke), CHF, drug (ACE-I), ILD, BOOP
Workup: ENT exam for s/sx allergic rhinitis, CXR +/- sputum if suspect infection, CT scan if suspect BOOP or chronic ILD, empiric antacid if hx c/w GERD.

Laryngomalacia

Definition

(Pediatr Rev 2006;27:e33)

Floppy tissue above vocal cords that falls into airway w/ inspiration
Collapse of supraglottic structures (arytenoids cartilages and epiglottis) w/ inspiration

Epidemiology

Most common cause of stridor in infants (∼65%–75% of all cases)

Clinical Manifestations

Begins during first 2 mo of life; infant usually happy/thriving
Noises are inspiratory and may sound like nasal congestion
Exacerbated with crying, agitation, or during an upper respiratory infection
Prone position may diminish the stridor

Diagnostic Studies

History/physical, flexible laryngoscopy, and/or bronchoscopy

Prognosis

Self-limited condition, usually resolves w/o Rx by 12–18 mo of age
In 10% of affected pts, upper airway obstruct severe enough to cause apnea or FTT

When to Refer

FTT, feeding difficulty, respiratory distress/apnea/hoarseness, cyanosis, atypical clinical course/persistent stridor

Interventions

Surgery: Supraglottoplasty

Croup

Definition

Clinical dx for acute onset of barky cough, stridor, and respiratory distress.

Epidemiology

(N Engl J Med 2008;358:4:384)

Affects children btw 6 mo–3yr old. Incidence in boys is 1.5×’s > girls.
Seasonal: Peak Sept-Dec, biennial. 5% of 2 yo will develop croup.

Clinical Course

(Lancet 2008;371:329; N Engl J Med 2008;358:4:384)

Typically 12–48 hr of preceding URI sx’s, followed by acute barky cough, hoarse voice, and respiratory distress, which are worse at night. +/- fever, mild pharyngitis. 60% children have resolution of symptoms in 48 hr.

Microbiology

Parainfluenza 1, 3, influenza A, B, adenovirus, RSV, metapneumovirus
Diphtherial and measles rare causes in nonvaccinated children (Lancet 2008;371:329)

Pathophysiology

Subglottic edema and airway narrowing.

Differential Diagnosis

(Lancet 2008;371:329)

Epiglottitis: Dysphagia, anxiety, sniffing position, toxic appearing
Bacterial tracheitis: 2–7 d prodrome, febrile, toxic, do not respond to epi nebs
Foreign body aspiration: Sudden, no fever
Retropharyngeal/peritonsillar abscess: Dysphagia, drooling, neck stiffness, unilateral cervical lymphadenopathy
Angioneurotic edema: Urticarial rash
Allergic reaction: Urticarial rash, history of allergy

Treatment

(Lancet 2008;371:329; N Engl J Med 2008;358:4:384)

Keep child comfortable, leave in parent’s arms. Blow-by oxygen, often held by parent
- Corticosteroids: Dexamethasone 0.6 mg/kg PO/IM ×1; duration of effect: 2–4 d
Racemic epinephrine: 0.5 mL of 2.25% racemic epi, or 5 mL of L-epi 1/1000
- Improves symptoms within 10–30 min. Effect lasts 1–2 hr.
Heliox: For severe resp distress. Lower density helium, mixed w/ O₂, ↓ turbulent flow through narrow airways. As good as, but more expensive than racemic epi.
No evidence that humidified air improves symptoms of croup. Antibiotics, antitussives, decongestants, or β₂-agonists do not have a role in the Rx of croup.
Monitored at least 2–4 hr after racemic epi Rx before d/c, ensure no recurrence
Observation for 3–10 hr in ER following Rx reduces admission rate for croup.

Obstructive Sleep Apnea Syndrome

(Arch Pediatr Adolesc Med 2005;159:775; Pediatrics 2002;109:704)

Definition

Breathing disorder during sleep w/ prolonged partial upper airway obstruct and/or intermittent complete obstruct (obstructive apnea); disrupts ventilation and sleep.
Needs to be distinguished from 1° snoring (PS), defined as snoring w/o obstructive apnea, frequent arousals from sleep, or gas exchange abnormalities.

Clinical Manifestations

Chronic snoring, daytime fatigue/sleepiness, sleep walking/talking, enuresis, periodic limb movement, headaches
Mouth breathing, nasal obstruct w/ wakefulness, adenoidal facies, hyponasal speech.
Neurocognitive deficits: Poor learning, behavioral problems, ADHD

Risk Factors

Adenotonsillar hypertrophy, obesity, craniofacial anomalies, neuromuscular d/o

Diagnosis

Pneumogram: Distinguishes between central and obstructive apnea
Polysomnography (PSG): Can distinguish PS from OSAS
- Quantitative, noninvasive eval of frequency/severity of sleep disordered breathing
- Confirm presence and severity of airflow obstruction; documents efficacy of Rx
- Help determine the risk of postoperative complications
- Determine the optimal level of CPAP when adenotonsillectomy is not an option
- Studies have not determined which polysomnographic criteria predict morbidity

Treatment

Adenotonsillectomy: The most common treatment for children with OSAS
- Resolution occurs in 75% to 100% after adenotonsillectomy
CPAP: Used indefinitely
- For patients with specific surgical contraindications, minimal adenotonsillar tissue or persistent OSAS after adenotonsillectomy
- Must be titrated in sleep lab before prescribing and needs periodic readjustment.