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In this section, you will learn about the following topics:

• Asthma/COPD

• Pulmonary Hypertension

• Pneumothorax/Chest Tubes

• PFTs

• Pleural Effusions

• OSA/OHS

• Tuberculosis/Hemoptysis

• Pulmonary Nodule/Lung Cancer

Asthma/COPD

Asthma and COPD are both chronic respiratory conditions that frequently lead to hospital admissions due to acute exacerbations. The focus is on rapidly relieving airway obstruction in asthma and providing aggressive bronchodilator therapy while addressing potential triggers, while COPD exacerbations often require oxygen supplementation and non-invasive or invasive ventilation as needed to manage severe respiratory distress.

When looking at both of these disease states you must first focus on airflow limitation. Airflow limitation is defined as an abnormally reduced ability to exhale - e.g. you can inhale and get air into your lungs but you cannot get air out. The severity of this limmitation is detemrined by evaluating the how much volume you can forcibly exhale in one second (known as the forced expiratory volume in one second, or FEV1) and the ratio of the FEV1 to the total forced expiratory volume (aka the forced vital capacity or FVC).

This limitation can either by fixed or may change in response to exogenous factors such as medications, environmental exposure and temperature. If there is significant variability in airflow limitation, then it is defined as asthma; if the airflow limitation is not fully reversible with medication, then it is defined as COPD.

Asthma

The Global Initiative for Asthma (GINA) defines asthma as a “chronic inflammatory disorder of the airways that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing. These episodes are associated with widespread, but variable, airflow obstruction that is often reversible either spontaneously or with treatment”. By this very definition it is obvious that the airflow obstruction is reversible, but often with longstanding asthma adults can develop persistent airflow limitation.

COPD

Chronic obstructive pulmonary disease represents an overlapping spectrum of airway diseases that cause persistent (and often progressive) air flow obstruction. In practice the diagnosis of COPD requires all three of the following to be true:

1. Pulmonary symptoms (dyspnea, cough, or sputum production)

2. Appropriate clinical context (most notably tobacco exposure), but can also include OSA, metabolic syndrome, heart disease)

3. Evidence of airflow limitation, usually seen on a PFT (not fully reversible with medication)

Asthma/COPD Overlap i(ACO)

When a patient has airflow obstruction that remits some but not completely, and they have appropriate risk factors, they are considered to have both asthma and COPD. In these patients COPD can be caused by cigarette smoking, but can also be caused by infections, pollution exposure, abnormal lung development and even unknown causes. There is no universal definition for this - most proposed definitions include age>40 years, history of asthma at younger age, persistent post-bronchodilator airflow obstruction, and evidence of partial bronchodilator reversibility.

There has been more evidence suggesting that the number of circulating eosinophils a patient has can cause different responds to inhaled glucocorticoids. Therefore, peripheral eosinophilia is recommended by GOLD to guide clinical pharmacotherapy in all patients with COPD. Subgroups of COPD patients with eosinophilia may experience clinical improvement with biologic medications shown to have benefit in asthma.

Resources to complete:

Pulmcast - As Good As GOLD with Dr. Antonio Anzueto

Pulmcast - Core Content: COPD

Pulmcast - The Curious Case of the Acidemic Asthmatic

Pulmonary Hypertension

Pulmonary hypertension (PH) is a progressive condition characterized by elevated blood pressure in the pulmonary arteries. It can lead to right heart failure and death if not appropriately managed. PH can be primary or secondary to other diseases and is classified into five major groups based on etiology, with specific diagnostic and treatment approaches for each.

There are five groups of pulmonary hypertension,

• Group 1: Pulmonary Arterial Hypertension (PAH) - In PAH, the narrowing of pulmonary arteries increases vascular resistance, which raises the workload on the right ventricle. PAH involves narrowing or constriction of the pulmonary arteries, leading to increased pressure. Common causes include:

  • Idiopathic PAH (IPAH)

  • Heritable PAH

  • PAH associated with connective tissue diseases (e.g., systemic sclerosis), HIV infection, portal hypertension, congenital heart disease, and certain drugs or toxins (e.g., methamphetamine, anorexigens)

• Group 2: PH due to Left Heart Disease - This is the most common cause of PH and occurs when left-sided heart conditions (e.g., heart failure, mitral or aortic valve disease) lead to increased pressure in the left atrium and pulmonary circulation. The primary issue is not in the lungs themselves but due to "backward" pressure from the left heart.

• Group 3: PH due to Lung Diseases and/or Hypoxia - Hypoxia leads to vasoconstriction of pulmonary arteries, and over time, chronic low oxygen levels can result in vascular remodeling and increased resistance in the pulmonary circulation.
  PH can arise secondary to chronic lung diseases, such as:

  • Chronic obstructive pulmonary disease (COPD)

  • Interstitial lung disease (ILD)

  • Sleep apnea

  • Chronic exposure to high altitudes

• Group 4: Chronic Thromboembolic Pulmonary Hypertension (CTEPH) - CTEPH occurs when pulmonary arteries are obstructed by old or unresolved blood clots. It can be mistaken for acute pulmonary embolism but leads to long-term pressure increases and right heart strain. A key feature of CTEPH is its potential curability through surgical intervention.

• Group 5: PH with Unclear or Multifactorial Mechanisms - This group includes conditions that don't fit into the other categories, such as:

  • Hematologic disorders (e.g., myeloproliferative diseases)

  • Systemic disorders (e.g., sarcoidosis, vasculitis)

  • Metabolic disorders (e.g., thyroid disease)

The treatment of PH depends on its underlying cause and severity. Goals include improving symptoms, slowing disease progression, and reducing complications like right heart failure.

Both Veletri (epoprostenol) and Remodulin (treprostinil) are prostacyclin analogs used to treat pulmonary arterial hypertension (PAH). While they share a common mechanism of action—vasodilation of the pulmonary arteries and inhibition of platelet aggregation—there are important differences between the two drugs, particularly in their pharmacokinetics, routes of administration, and clinical use.

Parenteral prostacyclin therapies:

• Endothelin Receptor Antagonists (ERAs): Examples include Ambrisentan (Letairis), Macitentan (Opsumit)

  • ERAs block the action of endothelin-1, a potent vasoconstrictor that contributes to the pathological vascular remodeling seen in PAH. By inhibiting endothelin’s effects, these agents promote vasodilation and reduce pulmonary vascular resistance.

  • Typically used in WHO Functional Class II-III PAH patients, but may also benefit Class IV patients when combined with other treatments. It’s often used early in the disease course for patients with mild-to-moderate PAH symptoms.

• Phosphodiesterase-5 Inhibitors (PDE-5 Inhibitors): Examples include Sildenafil (Revatio), Tadalafil (Adcirca)

  • PDE-5 inhibitors increase the availability of cyclic guanosine monophosphate (cGMP), which is a vasodilator. They do so by blocking the enzyme PDE-5, which normally breaks down cGMP. This leads to enhanced nitric oxide (NO)-mediated vasodilation, especially in the pulmonary vasculature.

  • First-line treatment for WHO Functional Class II-III PAH patients. It is frequently used in combination therapy with ERAs or prostacyclin analogs in patients with more severe disease. It is particularly effective in patients with idiopathic PAH and connective tissue disease-related PAH.

• Soluble Guanylate Cyclase (sGC) Stimulators: Examples include Riociguat (Adempas)

  • Riociguat enhances the effects of nitric oxide by directly stimulating soluble guanylate cyclase, leading to increased cGMP levels and potent vasodilation. It also works independently of nitric oxide, making it effective in patients with impaired NO signaling.

  • Approved for both PAH (Group 1 PH) and chronic thromboembolic pulmonary hypertension (CTEPH, Group 4 PH) that is inoperable or persists after surgery.

  • Used for WHO Functional Class II-III patients, often in combination with other PAH therapies. It os often second-line or add-on therapy for patients who fail or cannot tolerate PDE-5 inhibitors.

  • Particularly useful for patients with CTEPH, a unique feature among oral therapies.

• Prostacyclin IP Receptor Agonists: Examples include Selexipag (Uptravi)

  • Selexipag is a prostacyclin receptor agonist that stimulates the prostacyclin (IP) receptor, leading to vasodilation and inhibition of smooth muscle cell proliferation. It mimics the effects of endogenous prostacyclin without the complexities of infusion-based therapy. Approved for WHO Functional Class II-III PAH, often as part of combination therapy.

  • Can be added in patients who are progressing on oral monotherapy or who need an alternative to intravenous or subcutaneous prostacyclin therapy. Typically added in combination with ERAs and/or PDE-5 inhibitors in patients with more advanced PAH.

  • Can be used as a step-up therapy before considering parenteral prostacyclin therapy.

Parenteral prostacyclin therapies:

• Veletri (Epoprostenol): Primarily used in severe cases of PAH due to its potency, particularly in patients with WHO Functional Class III-IV PAH. It is often considered the gold standard for long-term IV therapy, especially in patients who are critically ill or refractory to other treatments. However, its continuous IV infusion requirements make it challenging in long-term management for some patients.

  • It is intravenous (IV) infusion only. Due to its short half-life, it must be administered through a continuous IV pump, often via a central venous catheter.

  • This route requires a higher level of care, including monitoring for infection at the catheter site and managing the complexity of pump-based delivery systems.

  • The half life is extremely short, around 3–6 minutes. This requires continuous infusion to maintain therapeutic effects. It is unstable at room temperature and requires careful handling, including refrigeration and reconstitution shortly before use (though Veletri, a newer formulation, is more stable compared to earlier versions like Flolan).

  • Common side effects include jaw pain, headache, flushing, diarrhea, and risk of catheter-related bloodstream infections. Abrupt discontinuation can be life-threatening due to the very short half-life, potentially leading to rebound pulmonary hypertension.

• Remodulin (Treprostinil): Due to its longer half-life and multiple routes of administration, Remodulin offers more flexibility in treatment and can be easier to manage in outpatient settings. It is also used in patients with WHO Functional Class II-IV PAH but offers an option for patients who prefer subcutaneous administration or have difficulty with continuous IV therapy. Subcutaneous administration can be associated with site pain, which is a common reason for patients to switch to IV or inhaled forms.

  • Remodulin can be administered by subcutaneous (SC), intravenous (IV), or inhaled routes. The subcutaneous route is particularly advantageous for outpatient settings, as it does not require a central line and reduces the risk of infections compared to IV delivery. The inhaled form (marketed as Tyvaso) offers another non-invasive option, though it may be less effective in patients with advanced disease.

  • It has a much longer half life, approximately 4 hours, allowing for more flexibility in dosing and administration. Treprostinil is more chemically stable and does not require refrigeration after mixing, making it easier to handle in outpatient settings.

  • Similar side effects to epoprostenol, such as headache, flushing, diarrhea, and pain at the injection site (especially with subcutaneous administration). The longer half-life reduces the risk of rebound PH in case of temporary interruption, but abrupt discontinuation still poses a risk.

Resources to complete:

Pulmcast - The Diagnosis of Pulmonary Hypertension with Dr. Chad Miller and Dr. Craig Patterson

Pneumothorax/Chest Tubes

Pneumothoraces are commonly encountered in the inpatient realm, where prompt recognition and intervention can be crucial. Chest tubes are inserted to evacuate air or fluid from the pleural space, relieving pressure on the affected lung and facilitating re-expansion.

A primary spontaneous pneumothorax occurs in the absence of underlying lung disease. It is caused by the spontaneous rupture of small air-filled sacs, known as blebs or bullae, on the lung surface, which allows air to leak into the pleural space.

• Typically seen in young, healthy individuals, especially tall, thin males aged 10–30 years. Associated risk factors include smoking, which increases the likelihood of bleb formation, and family history.

• Patients present with sudden onset of pleuritic chest pain and dyspnea; it is often mild and may resolve on its own, though large pneumothoraces can cause more significant symptoms.

A secondary spontaneous pneumothorax occurs in patients with underlying lung disease. The air leak is often due to a rupture of abnormal lung tissue caused by conditions such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, tuberculosis, or interstitial lung disease. Patients may present with acute respiratory distress due to the already compromised lung function from their underlying disease.

• Symptoms include chest pain, dyspnea, tachypnea, and hypoxia. It is more common in older patients with chronic lung conditions; COPD is the most common cause, particularly in those with emphysema, where lung parenchyma is weakened and prone to rupture.

A traumatic pneumothorax results from blunt or penetrating trauma to the chest, which causes disruption of the pleural membrane and allows air to enter the pleural space. Blunt trauma includes motor vehicle accidents, falls, or sports injuries can cause rib fractures that puncture the lung. Penetrating trauma includes stab wounds or gunshot wounds directly disrupt the pleura. The most common thing we will see at our hospital is iatrogenic trauma, caused by medical procedures such as central venous catheter placement, thoracentesis, mechanical ventilation, or lung biopsies.

Small, asymptomatic pneumothoraces may be observed with close monitoring and supplemental oxygen. Secondary spontaneous pneumothorax tend to be more aggressive. Larger pneumothoraces or symptomatic patients may require needle aspiration or chest tube drainage.

Resources to complete:

Pulmcast: Needle Decompression

Pulmonary Function Tests

A pulmonary function test is very useful for the diagnosis of lung disease. Normal values for the test are based on age, height, weight, gender and race; there are three components of a complete PFT - Spriometry (FVC/FEV1), lung volumes (TLC) and DLCO.

The first component is Spirometry. This is used whether to determine if airway obstruction is present; with this, you will obtain a FVC (forced vital capacity; forceful exhalation of all air out of lungs after deep inspiration), FEV1 (forced expiratory volume exhaled in the first second). You will also calculate a FEV1/FVC ratio. If this ratio is <0.7 (70%), this is DIAGNOSITIC for airflow obstruction.

• In order to know a good enough effort was made, you need to check the flow volume loop for at least six seconds of exhalation without coughing or multiple breaths

• You should NOT order spirometry when a patient has recent thoracic, abdominal, intracranial or Opthalmic surgery (other than simple cataracts); pneumothorax within the past month; acute MI; altered mental status (patient won’t be able to perform study); large pleural effusions (will not provide any significant data); decompensated heart failure with pulmonary edema (wait until euvolemic). This is all pretty obvious - anything that affects your ability to exhale.

The second component you look at is lung volumes. This is used to identify restrictive lung diseases, air trapping, or hyperventilation. This is interpreted in CONJUNCTION with spirometry.

• TLC (Total lung capacity) = VC (vital capacity, also known as slow vital capacity) + RV (residual volume, the amount of air left in the lung safter complete exhalation)

• If a patient is very obese, they may not be able to fit into booth to perform test

The third component is Diffusion Capacity for Carbon Monoxide (DLCO). This determines efficiency of gas exchange in the lungs. It is used to diagnose interstitial lung diseases, thromboembolic diseases, assess degree of emphysema. In order to do this, the patient MUST be able to hold their breath for at least 10 seconds.

Obstructive Lung Disease

For patients with obstructive lung physiology, there is an issue with actually getting air OUT of the lungs.

Restrictive Lung Disease

For patients with restrictive lung physiology, there is usually one of three causes: the tissue, the body or the muscles.

• Tissue - Interstitial Lung Disease. Rule out ILD; Work-up involves HRCT and serologies.

• Body - Body Habitus. Takes a lot of force to move a thick chest wall

• Muscles - Neuromuscular Weakness. Severe MS, ALS. Check NIF/FVC

Pulmonary Effusions

Pleural effusions, the accumulation of fluid in the pleural cavity, often have diverse etiologies and require prompt treatment when they compromise respiratory function. Procedures like thoracentesis or chest tube placement may be performed to drain the effusion and improve lung function.

Resources to complete:

OSA/OHS

Obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS) can lead to acute respiratory failure, especially in patients with comorbidities, necessitating ICU monitoring and support. OSA may be managed with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), while OHS may require invasive mechanical ventilation and addressing underlying obesity.

Resources to complete:

Pulmcast: So You Think Your Patient Has Sleep Apnea?

Tuberculosis/Hemoptysis

Tuberculosis and hemoptysis may require ICU care in cases of severe respiratory compromise or massive hemorrhage. Aggressive treatment of tuberculosis with appropriate antibiotics and interventions to control hemoptysis, such as bronchial artery embolization, may be undertaken in the ICU.

Resources to complete:

Pulmonary Nodule/Lung Cancer

Pulmonary nodules and lung cancer are often discovered incidentally or during the evaluation of respiratory symptoms. Inpatient the focus is on managing complications like respiratory distress or bleeding, as well as addressing oncological issues with a multidisciplinary approach involving oncologists and pulmonologists to determine the best course of treatment and intervention.

Resources to complete:

Pulmcast: Sarcoidosis, Beyond 40mg of Prednisone with Dr. Baughman