Tag: lungs

Why We Need to Re-Evaluate the Racialized History of Spirometry

One of the leading indicators of good health is adequate lung capacity. Lung capacity, as defined by Bajaj and Delgado is the volume of air in the lungs upon the maximum effort of inspiration. For an average healthy adult, that is about 5.5 liters of air. But how do we measure our lung capacity? A spirometer is the answer. Even though the device has undergone multiple revisions since it was first invented in the 1840s, it has not deviated away from its original purpose of measuring lung capacity.

Luckily, the function of a spirometer is very intuitive to understand. One type of spirometer, called the pneumotachograph spirometer, measures the amount of air a person exhales and inhales in a second. Here is a quick run through of how that happens. The pneumotachograph spirometer typically consists of a tube, a flowmeter and a sensor. The tube is responsible for converting the information gathered by the sensor to an electric signal. The information carried by the signal is then displayed using a spirogram, a graph with flow rate (volume per second) plotted against inhaled air volume (meters cubed). Based on the characteristics of the graph, the health personnel conducting the test can then analyze the lung capacity of the subject.

Basic set-up of a spirometer test Source:Wikipedia

What are some lung conditions that a spirometer can help us diagnose? It can help us diagnose Asthma, determine if our airways have become narrowed or if our lungs are congested by mucus (pulmonary fibrosis). Another condition on the list of diagnosis is cystic fibrosis, a rare chronic condition that alters  the function of body parts such as the lung and liver by producing mucus. Our vital capacities can be compromised for different reasons eventually causing the aforementioned defects in our health. Some of the reasons are partly hereditary(such as cystic fibrosis) but most of these are caused by external factors such as smoking and exposure to polluted air. Other factors cited in early medical studies include race, gender and age.

The difference in lung capacity between white people and colored people has been a widely accepted phenomenon. For a long time the broader medical community believed that lung capacity difference was innate. As a result, “race corrections” are applied on the spirometer results in an attempt to get a more accurate value. The correction factor shrinks the benchmark for standard lung capacity of black people by 10% and Asian people by 4% to 6%.

This obviously calls into question who the system designated as the benchmark of health and normalcy – the white population. The “race correction” doesn’t acknowledge the intersections of socio-economic status, exposure to cleaner air, or sex. These are all factors that can largely influence well-being including but not limited to lung capacity.

Why does this matter? It matters because race correction could result in the deprivation of the necessary medical attention that needs to be given to colored communities. It also overlooks the intersectionality of their experiences that exist in the spheres of social class, environmental factors, and lived experiences. Thus, we need to question how race correction was installed in the first place. Was it a pure speculation? Was it devised as a result of segregative policies? Or did it have an empirical basis? That is why it is important to put the spirometer in a historical context and reevaluate the implicit biases with which it was designed.

References and Further Readings:

Braun, Lundy. “Race, ethnicity and lung function: A brief history.” Canadian journal of respiratory therapy : CJRT = Revue canadienne de la therapie respiratoire : RCTR vol. 51,4 (2015): 99-101. Link

Haynes, Jeffrey M. “Basic spirometry testing and interpretation for the primary care provider.” Canadian journal of respiratory therapy : CJRT = Revue canadienne de la therapie respiratoire : RCTR vol. 54,4 (2018): 10.29390/cjrt-2018-017. doi:10.29390/cjrt-2018-017

Braun, Lundy. Breathing Race Into the Machine: The Surprising Career of the Spirometer from Plantation to Genetics. N.p., University of Minnesota Press, 2014. Link

González, Jorge:Spirometer Demo with Freescale Microcontrollers, NXP, 2012.
A brief history of the spirometer

Prof. Klapperich et al.

the novel coronavirus: how an invisible invader halted the world

Last year the world changed. With modifications to daily life such as wearing masks and attending class online, a lot of what was common became uncommon. More severely, millions of deaths globally shook the world. All of this change and devastation can be attributed to a coronavirus variant that was shockingly good at two things… 1.) Stability outside of cells 2.) Breaching the lower respiratory tract. A few questions must be understood as to why this virus is so effective in its affinity towards destruction. First, How does COVID-19 penetrate a cell? How does COVID 19 replicate? Finally, why is COVID-19 able to survive outside of a cell so well?

Detailing of S spike Proteins on Coronavirus Molecule
Coronavirus Spike Illustration Provided by NIH

With regards to cellular penetration, Coronavirus has two main parts in order to enter a cell. The first part is the use of its spike-like proteins to bind to the outside of a cell, otherwise known as the cell’s surface receptors. This spiky outer layer of the coronavirus makes it easily bindable to a number of human cells. After an initial bind between the coronavirus and the cell’s surface receptors, the coronavirus is absorbed into the inside of the cell, analogous to the way an amoeba absorbs an organism. The second part of this process involves what is called protein priming. Before entering the cell, coronavirus primes the S protein through the host cell’s proteases. From there, the S protein allows for ACE-2 binding which can be thought of as the mode for physically transporting the coronavirus into the cell. The current variant of Coronavirus is exceptionally dangerous because its spike proteins are able to attach to cells in the lower respiratory tract, a very vulnerable system in many humans.

Scanning Electron Micrograph of Coronavirus infected tissue
Coronavirus Scanning Electron Micrograph From Patient

Once in the cell, coronavirus seeks to reproduce. In order to reproduce, Coronavirus seeks out ribosomes to make copies. The viral molecule carries the blueprint on how to convert RNA into more RNA via creating a polymerase. This polymerase reproduces the genetic RNA genome and ultimately forces the ribosomes to produce more Coronavirus molecules. Because there are millions of ribosomes in every human cell, it does not take long for this process to occur. One of the key modes of trying to treat people with extreme cases is medicine that targets this polymerase. The drug fakes out the polymerase into replicating genomic material that will not lead to greater virus production.

Coroanvirus armor and encasement illustrated.
Coronavirus armor and encasement illustration from Scientificanimations.com

Finally, Coronavirus is exceptional at surviving outside of the cellular environment. It has been noted that in the right conditions (humid), coronavirus can survive on a given surface anywhere from a few hours to 9 days. On paper, the virus may only survive for a few hours while on glass, the virus can exist for 5 days. Why Coronavirus is able to survive on these surfaces relates back to its spike proteins. These proteins act as armor in protecting the genomic material inside the virus. If this armor is broken, the genome of the virus is spilled out as well the virus no longer having a physical form.

Understanding is the first step in disarming. By having a better understanding of how coronavirus binds and enters into cells, replicates, and survives in outside environments, better strategies to prevent the spread of this dangerous virus can be better developed.

Not Everyone Breathes While they Sleep: The Dangers of Sleep Apnea

You might think that breathing in our sleep should come naturally – if breathing and sleeping are both physiologically necessary, then we must be able to do them simultaneously right? Unfortunately, almost a quarter of middle-aged American men and nearly 10% of women suffer from sleep apnea, a chronic condition characterized by repeatedly stopping breathing while sleeping. The clinical symptoms seem rather benign – snoring, sleepiness, fatigue during the day or other issues sleeping. However, by far the most dangerous aspect of this disease is that it puts patients at increased risk of high blood pressure, stroke, coronary heart disease, as well as occupational and/or automobile accidents. Over the last several decades, a variety of therapy options have been studied to treat this condition, ranging from drugs to masks to surgery.

One of the earliest documented therapy options is using protriptyline to treat obstructive sleep apnea. Protriptyline is an anti-depressant drug that was used for its ability to clear airway obstructions during sleep; however, it did not gain significant popularity due to its adverse effects including cardiac complications and limited demographics for whom it would be an appropriate treatment.

The next treatment discussed was altering sleep positions for patients suffering from sleep apnea. A seemingly simple idea, a study determined that laying on the back significantly increased the severity of sleep apnea. Interestingly, the difference in severity between back and side sleeping positions was most noticeable in healthy, non-obese patients. The authors believe that lying on the back causes tissues of the throat to obstruct the trachea and prevent smooth airflow during breathing, as shown in the image below, which would explain why obesity can exacerbate sleep apnea.

Diagram of airflow obstruction through mouth and throat
Photo by Habib M’Henni on Wikimedia Commons.

Multiple non-invasive devices were also studied, including oral appliances, sleep posture alarms, and positive airway pressure devices. Oral appliances can either protrude the lower jaw or restrain the tongue; both aim to restructure the upper airway (mouth, trachea, etc.). Sleep posture alarms were suggested to train patients to sleep on either side, rather than on their backs. Positive airway pressure devices (Bi-PAP, CPAP) are the most commonly used treatment for sleep apnea currently; they maintain a consistent air pressure flowing into the mouth to ensure the airways do not collapse during sleep.

Man sleeping while using CPAP machine
Photo by ApneaMed

The final treatment studied was nocturnal supplemental oxygen (NSO), which involves increasing the concentration of oxygen in the air inhaled while sleeping. However, a study comparing use of a CPAP with use of NSO found that CPAP treatment was far more effective at decreasing the patients’ blood pressure and still proved effective in patients already taking blood pressure medication.

Overall, the best method for treating sleep apnea is dependent on the patient and his or her underlying conditions. Changes in sleep posture could greatly enhance the sleep quality of a moderate case of sleep apnea; CPAP would be ideal for someone who can easily tolerate the mask and does not frequently move in his or her sleep. Each of these demographics makes it difficult to define one optimal solution for treating sleep apnea, but the variety of available treatment options provides hope for those patients who suffer from this chronic illness.

How to Shine at Karaoke and Master the Art of Singing

Woman singing with microphone
Photo by Josh Rocklage on Unsplash

Are you tired of going to karaoke with your friends and not being able to master those high notes like singers Whitney Houston or Mariah Carey? While this blog post cannot promise the high quality of those amazing singers, it will demonstrate how through practice you can master the art of singing. To master singing you must first understand the biology and mechanics of your singing voice, so you can learn how to manipulate both to your benefit. This can extend to vocal production and communication studies, but the focus will be singing.

Diagram of vocal system including larynx, vocal cords, trachea
From University Physics Volume 1 on Wikimedia Commons

The vocal anatomy in the human body is composed of vocal chords, the larynx or voice box, trachea, diaphragm muscle, and airflow passages. Vocal chords, commonly referred as vocal folds, are flexible and delicate tissues that can withstand high frequency vibrations. The larynx is a tube in the human neck that holds the vocal chords. The trachea is a long tube that extends from the larynx and passes air to and from the lungs, otherwise known as the windpipe. Lastly, the diaphragm is a large muscle that separates the cavity containing the heart and lungs from the abdominal cavity. These definitions will become useful when discussing the process of singing.


Diagram of the respiratory system including the diaphragm, lunch, and trachea
From BruceBlaus on Wikimedia Commons

The organization Learn to Play Music described the biological process involved in singing in a blogpost. As humans inhale, the diaphragms contracts, the lungs expand and draw in air. During exhalation, the diaphragm relaxes, and air exits through the lungs. As air exits the “breath” travels upward through the trachea and vocal chords which begin to vibrate. This vibration leads to the production of sound which is then augmented (made louder) by areas of mouth, throat, and behind the nose. Additionally, these spaces allow the sound by vibration to last longer and affect the tone of a person’s voice. The shape of a person’s mouth, tongue, and lip movements can change the way the sound leaves the mouth by shaping the sound produced.

Music Professor Leigh Carriage at Southern Cross University analyzed how to use biomechanics to improve singing in an article. Singing involves varying pitches, loudness, voice quality (raspy, breathy, clear sounding) which requires control and coordination of muscles. These muscles must be flexible and strong which can be formed by practicing breathing control. To master singing a person needs to control the air pressure in their lungs and use their abdominal muscles to control the air flow. The most efficient way to control this pressure is through repetition or regular singing. This practice would strengthen the vocal system and improves vocal tone and power. Additionally, further expanding the abdomen when inhaling can lead to an increased contraction of the diaphragm. This would allow for more breath support when it comes to changing tone, pitch, or holding a note.

There are many biological and mechanical aspects to singing that can be analyzed to control the singing voice. See two additional readings here and here to learn more. Overall, practicing the control of your breathing during inhalation and exhalation helps master singing. By controlling the air flow, you can improve tone, pitch, and the power behind your voice at karaoke!


Check out this cool video!




The Study of Snoring is Anything but Boring

Here we take a deeper look about that noise that plagues some of our family members, our roommates…or even ourselves!

Elderly man sitting in the sun, asleep with head back and mouth open.
Photo by Stephen Oliver on Unsplash

What Causes You to Snore in the First Place?

The human upper airway contains anatomical parts that are membranous, meaning they lack support from cartilage. Some parts include the tongue, the soft palate, and the tonsillar pillars. A lack of cartilaginous support enables these parts of the airway to be susceptible to vibrations.

Anatomical diagram of the human upper airway.
Modified from Huang, Quinn, Ellis, and Williams, “Biomechanics of Snoring,” from Endeavor, 1995.

During sleep the upper airway muscles relax and cause the size of the airway space to decrease, resulting in airflow limitation and turbulence.

Whenever we inhale, the turbulent flow through the relaxed airway causes those membranous structures to vibrate and produce a sound most commonly known as snoring.

A Brief Mechanical Explanation of Snoring

Examining snoring in the view of mechanical systems, respiratory noise is created by the oscillation of the upper airway with the air passing through it. This oscillation is indicative of an issue with flow instability (turbulent flow) over a flexible structure (the relaxed airway).

An experiment was created to model the movement of the soft palate during snoring, where a piece of wood was used to simulate the hard palate and a piece of leather simulated the soft palate. The leather and wood were attached to each other inside of a rigid tube that was connected to a pump (meant to model the lung inspiration).

During inspiration, the leather flap oscillated until it reached its full amplitude. Upon reaching the maximum amplitude, the leather flap hit the wall of the tube and created a noise known as palatal “flutter”. This palatal flutter is the most common method of noise production in humans: snoring.

Is Snoring Something to Be Concerned About?

Young woman waking up in the morning, appearing tired.
Photo by Kinga Cichewicz on Unsplash

Approximately 44% of men and 28% of women are habitual snorers.

Snoring can be a symptom of obstructive sleep apnea, a condition distinguished by snoring and breathing that is labored by repetitive and obstructive gasps.

The fragmented sleep resulting from sleep apnea can lead to decreased energy and poor attention and concentration. Sleep apnea can also be related to vascular issues like hypertension and its prevalence appears to increase in people over 65 years of age.

What Are Some Remedies to Snoring?

Remedies for snoring range from noninvasive devices to invasive surgical procedures.

The surgical option to remedy snoring involves removing a portion of the vibratory tissue from the back of the upper airway. For those people wanting to avoid surgery, non-invasive solutions include the use of nasal strips to lift and open the nasal passages; experimenting with sleep positions other than sleeping on the back; or using oral appliances and nasal continuous positive airway pressure (nCPAP) to prevent the tongue and soft palate from collapsing into the upper airway. Losing weight, avoiding smoking and alcohol can also help to reduce snoring.

There are also resources for snoring in kids, as well as additional home remedies and surgical information regarding snoring.

Below is a great animated video which gives an introductory explanation to snoring.