Lung Matters – A Four Part Series - Part Three

In this edition, I’ll begin by describing a few non-ventilatory functions of the respiratory system - sighing, yawning, and laughter. Additionally, I will provide an overview of COPD therapeutics, oxygen delivery modalities, and lastly, the effect of altitude on exercise ability.

What is a sigh?

A sigh is a prolonged expiratory spell that is often reflexive and can relieve anxiety and stress.  A person’s lack of ability to sigh is associated with SIDS or sudden infant death syndrome, yet on the other hand, excessive sighing can actually provoke anxiety and hyperventilation syndrome.

Why is yawning contagious and laughter infectious?

Yawning has been a mystery to physiologists and researchers for quite some time now. A yawning episode, which typically lasts for 5 seconds, is a reflex that results in the involuntary wide opening of the mouth, with maximal widening of the jaw, and a long and deep inhalation through the mouth and nose, followed by a slow expiration, associated with a feeling of comfort (a long reflex, indeed!). Yawning occurs before and after sleep, and during tedious or monotonous activity. It causes an increase in heart rate and an alerting neurological response, similar to that of caffeine. It also functions in cooling the brain and decreasing pressure in the inner ears. Yawning also produces a mirror response in people observing it and both talking and thinking about it!

Ah, laughter – how good it is!  Gelotology, originated from the Greek word “gelos” or “laughter”, and as the name implies, is the study of laughter from a psychological and physiological perspective.  Laughter is a physiological response to humor and it involves short expiratory bursts and the activation of more than a dozen facial muscles - especially the zygomatic major, which is the main muscle group that elevates the upper lip and generates a wave of electrical activity in the cerebral cortex and the limbic system. Laughter can be cleansing and a welcome break from stressful situations. In humans, laughter is an evolutionary adaptation to manage stress, anxiety, and fear and to appreciate incongruity and improve human bonding.

Overview of COPD Therapeutics

The cornerstone of COPD therapeutics revolves around 2 classes of medications delivered in a respirable form that open or dilate narrowed or obstructed airways, especially the bronchi.

Beta-agonist or beta adrenergic agonists are drugs that work on the beta 2 type of adrenergic receptors in the bronchi.  They are also the major class of bronchodilators and have short acting and long acting types abbreviated as SABA and LABA, respectively.  Anticholinergics or anti-muscarinic agents act by blocking receptors called muscarinic receptors that predominate in the lungs and help by opening up airways and decreasing excessive respiratory secretions. Anti-muscarinic agents fall under short and long acting classes abbreviated as SAMA and LAMA, respectively.

Anti-inflammatory Medications

Inhaled corticosteroids are the mainstay of the management of asthma, but only have a limited role in regards to COPD.  Acute exacerbation of COPD, or AECOPD (Acute Exacerbation of Chronic Obstructive Pulmonary Disease), is characterized by an abrupt increase in coughing, with excessive sputum production and shortness of breath.  These episodes are believed to be triggered by a bacterial overgrowth in the bronchi, which are called bronchitic exacerbations and are treated with antibiotics and steroids.  Steroids in the intravenous form via solumedrol and or in the oral form via prednisone are commonly used for treating these episodes, typically for a 5-10 day period as a burst, or as a burst followed by a taper.

Novel anti-inflammatory Medications

PGD 4 or Phosphodiesteras 4 inhibitors are a new class of medication that has provided some benefits in decreasing the inflammatory process in the lungs. Roflumilast is available as a pill, marketed as Daliresp.

Referenced below is the ever-expanding list of medications for COPD that are available in the market currently.

SABA

• Albuterol- Proair, Proventil, Ventolin
• Levalbulterol- Xopenex
• Both albuterol and levalbuterol are available in liquid form to use in a nebulizer

LAMA

• Salmeterol- Serevent
• Formoterol- Foradil
• Indacaterol- Arcapta
• Olodaterol- Striverdi

LAMA available for nebulizer use

• Formoterol- Perforomist
• Arformoterol- Brovana

SAMA

• Iptratropium bromide- available as an inhaler Atrovent and in nebulized form
• SABA/SAMA combination inhaler is marketed as Combivent as an inhaler and Duoneb for nebulizer use

LAMA

• Tiotropium- Spiriva available in 2 different delivery form handihaler and as a respimat
• Aclidinium- Tudorza Pressair
• Umeclidinium- Incruse Ellipta

LAMA/LABA combination

• Umeclidinium/Vilanterol- Anoro Ellipta
• Glycopyrrolate/Formoterol- Bevespi Aerosphere
• Tiotropium/Olodaterol- Stiolto Respimat
• The newest class of approved is LAMA for nebulizer use approved by FDA
• Glycopyrrolate – Lonhala Magnair

Oxygen Delivery in the Critically Ill

FiO2 expresses the percentage of oxygen in the air.  Room air, if you didn’t know, has 21% oxygen.  Oxygen via a nasal cannula provides additional 4% oxygen for every 1 liter/minute of flow rate and oxygen in this form cannot exceed 6 liters, usually given the severe dryness and irritation of the nasal passages.  It is known, though, that humidification can improve one’s tolerance, especially at high flow rates, and that a simple oxygen mask can deliver flow rates of 6-10 liters. A venti mask or a venturi mask named after a famed Italian Physicist, Giovanni Battista Venturi, is considered an air entrainment mask that can deliver a specific percentage of oxygen by employing a choke valve or a pipe that causes a jet effect and changes fluid pressure.  A venti mask can deliver O2 concentration of up to 50% FiO2. A non-rebreather mask or a NRB mask can deliver up to 90% FiO2, and a bag mask valve or a BMV can deliver 100% FiO2!

A high flow oxygen or a HFO system uses a nasal cannula or nasal prongs, heats and humidifies O2, to be able to deliver O2 at very high flow rates of 40-60L/min at a specified FiO2.

Mechanical ventilation, either noninvasively via a face mask or invasively via an endotracheal tube, is considered when above measures are inadequate to maintain oxygenation goals.

Altitude and Exercise

Although the percentage of oxygen at higher elevations remains fairly steady at 21%, the air is thinner and the partial pressure of oxygen is lower. This makes it difficult for the body to utilize O2 and has a multitude of physiological consequences and adaptations.

In the short term study, a higher respiratory effort, both the rate and depth of breathing increased and a higher level of erythropoietin (a hormone produced by the kidney that promotes the formation of red blood cells by the bone marrow) was secreted by the kidneys.  Erythropoietin or EPO gets secreted by the kidneys to more efficiently transport oxygen.

Favorable adaptation to hypoxia (when the body or a region of the body is deprived of adequate oxygen supply at the tissue level) at higher elevation at  the cellular level includes more efficient mitochondrial metabolism and accelerated angiogenesis, or formation of new blood vessels at the microvascular environment.

In the 1968 Mexico Olympics held at an altitude of 2300meters or 7282 feet, it was observed that most endurance records were set back presumably due to rarified air and low oxygen pressures. However, the explosive events like sprinters and long jumpers did exceptionally well, likely due to less air resistance and being independent of O2 supply, or in other words anaerobic.

Wish you all a Very Happy Holidays, Merry Christmas and Happy New Year full of laughter, joy and an abundance of health.

Cheers!

Rajan Sadagopal K. Subbiah MD, is a Pulmonary and Critical Care Medicine Specialist and sees patients in Crystal Run's Newburgh and Rock Hill offices.