Thoracic and Sleep Group Queensland People caring for how you breathe and sleep

Thunderstorm-asthma has made headlines in Victoria recently after claiming the lives of two people and hospitalising dozens more, however, this phenomenon is far from new.  Thunderstorms have been linked to asthma epidemics, especially during the pollen seasons, and there are descriptions of asthma outbreaks associated with thunderstorms, which occurred in several cities, prevalently in Europe (Birmingham and London in the UK and Napoli in Italy) and Australia (Melbourne and Wagga Wagga).

It has been demonstrated that changes in the weather, such as rain or humidity, may induce hydration of pollen grains and sometimes also their fragmentation, which generates atmospheric biological aerosols carrying allergens.

During the first phase of a thunderstorm, pollinosis subjects may inhale a high concentration of allergenic material dispersed in atmosphere, which can induce asthmatic reactions and sometimes even severe ones. In other words, there is evidence that under wet conditions or during thunderstorms, pollen grains may, after rupture by osmotic shock, release into the atmosphere part of their content, including respirable, allergen-carrying cytoplasmic starch granules (0.5–2.5 μm) or other paucimicronic components that can reach lower airways inducing asthma reactions in pollinosis patients.

Fortunately, although it can induce severe asthma, outbreaks associated with thunderstorms are neither frequent nor responsible for high entity of disease exacerbations. However, the mechanisms involved in the release of allergens from pollens during thunderstorm should be known so that pollinosis patients can receive information about the risk of an asthma attack also in subjects affected only by seasonal allergic rhinitis.

Although thunderstorm-associated asthma outbreaks are not frequent, it is possible to observe in clinical practice single cases of patients with deterioration of the allergic respiratory symptoms during a thunderstorm and this possibility should be considered, because the frequency of thunderstorms is recently increased in some geographical areas, particularly in temperate and subtropical climate.

The characteristics of described epidemics of thunderstorm-associated asthma can be summarized as follows:

• There is a link between asthma epidemics and thunderstorm.
• The epidemics related to thunderstorm are limited to seasons when there are high atmospheric concentrations of airborne allergenic pollens.
• There is a close temporal association between the start of the thunderstorm and the onset of epidemics.
• There are not high levels of gaseous and particulate components of air pollution.
• Subjects with pollen allergy, who stay indoors with window closed during thunderstorm, are not involved.
• There is a major risk for the subjects who are not under antiasthma correct treatment, but subjects with allergic rhinitis and without previous asthma can experience severe bronchoconstriction.

In the light of the above, subjects affected by pollen allergy should be alert to the danger of being outdoors during a thunderstorm in the pollen season, as such events may be an important cause of severe exacerbations of asthma

In other words, when asthmatic patients realize that a thunderstorm is approaching the best thing for them to do is to stay indoors, with windows closed.

D’Amato, G., Liccardi, G. and Frenguelli, G. (2007), Thunderstorm-asthma and pollen allergy. Allergy, 62: 11–16. doi:10.1111/j.1398-9995.2006.01271.x

The STOP BANG questionnaire is a screening tool for Obstructive Sleep Apnoea (OSA). It was first developed in 2008 by Chung et al. as a screening tool for preoperative patients, the STOP element of the questionnaire was tested among for this patient cohort.^1,3 What they found was that the STOP questionnaire worked well for identifying severe OSA in this cohort, as well as being an easy test to administer and that it provided reliable results when tested again.^1,3 However we know that surgical patients have a higher prevalence of OSA than the normal population, they then added the BANG section to the questionnaire to provide better sensitivity for patients with moderate OSA.³

The STOP BANG questionnaire is an acronym for the elements of the test. This is a yes/no questionnaire with a score of 1 added for each positive or “yes” answer for that category. Scores of 0-8 are possible, with scores of 3 and above being suggestive of OSA, however the higher the score the higher the risk of OSA. The elements that make up the STOP BANG are common indications/risk factors for OSA and you are likely to routinely screen for these in clinical practice.

S – Snoring – Do you snore? Is it as loud as or louder than talking?

T – Tiredness – Do you wake up tired, or do you become tired during the day?

O – Observed Apnoeas – Have you felt or has anyone else told you that you stop breathing in your sleep?

P – Hypertension – Do you have high blood pressure, or are you on medication for high blood pressure?

B – BMI > 35kg/m²?

A – Age > 50 years?

N – Neck circumference > 40cm

G – Gender male?

Why is this important?

Most physicians are well aware of the disease burden of OSA in the Australian community and the associated co-morbidities and risks of undiagnosed and untreated obstructive sleep apnoea.² Recently the medicare benefits schedule review taskforce released a report from the thoracic medicine clinical committee. Their first recommendation (relating to sleep studies) is to:

“Improve the triage of patients to testing, supporting direct GP referral through use of validated clinical assessment tools that identify uncomplicated patients with high pre-test probability of symptomatic moderate to severe OSA.”

There is estimated that 4.7% of the Australian population have OSA and that an annual health care cost of $408.5 million can be directly attributed to sleep apnoeas. ² In addition to this there is an indirect cost of $2.6 billion attributed to OSA in Australia.²

Does the STOP BANG work?

The STOP BANG has been extensively tested over the past 7 years. The common theme coming from the research is that the test has high sensitivity, but less specificity (false negatives). Scores of 0-2 may be classified low risk for moderate to severe OSA, whereas a score of 7-8 is high risk for moderate to severe OSA.⁵ Most of the research agree that a score of 3 or above is suggestive of OSA, the statistics may vary slightly depending on the patient cohort tested, with the results generally showing that between 60-90% of patients with a STOP BANG score of 3 as having an AHI > 15. ^3,5,6,7 AHI of 15 is often referred to as moderate OSA. The interesting thing about these scores is that the probability of OSA increases proportionally with increases in STOP BANG scores.⁷

Can it be better?

It seems that some of the elements within the STOP BANG may not be equal, for example BMI > 35 + a score of 2 from the STOP section of the STOP BANG will increase the sensitivity of the test.⁴ However as a screening tool just as it is, it has been proven quite effective. The clinical judgement of the medical practitioner examining the patient is of significant importance too, and this screening tool is not designed to replace this.

Other screening tools do exist, but these are either not as sensitive or easy to use as the STOP BANG, these include; the ASA checklist, Berlin questionnaire, Epworth sleepiness scale and Stamford sleepiness scale.

For more information on screening for sleep disorders, referral practices or patient care options please:

• visit our website (http://thoracicandsleep.com.au/doctors-information/)
• or free call: 1300272688 (1300 A SCOTT)

Resources:

• https://www.ncbi.nlm.nih.gov/pubmed/18431116
• http://www.sleephealthfoundation.org.au/pdfs/news/Reawakening%20Australia.pdf
• http://www.nursingcenter.com/journalarticle?Article_ID=3256055&Journal_ID=54033&Issue_ID=3256011
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4153119/
• https://www.ncbi.nlm.nih.gov/pubmed/26378880
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008971/
• https://www.ncbi.nlm.nih.gov/pubmed/26658438

A recent study published in this month’s issue of SLEEP has assessed a new measure of positive airway pressure (PAP) effectiveness, the Effective AHI. An accepted metric to define the effectiveness of PAP for the treatment of obstructive sleep apnoea (OSA) is hours of home use, however this is a surrogate measure as it does not directly assess the apnoea hypopnoea index (AHI).  Boyd et al. developed the Effective AHI which accounts for sleep disordered breathing events during the time PAP is and is not being used, to quantify residual disease burden. As the Effective AHI can also be used to assess the effectiveness of any OSA treatment it can facilitate selection of the most effective therapy for a patient.

Positive airway pressure is the accepted first line therapy for patients with OSA and is highly efficacious, however its effectiveness of managing sleep disordered breathing (SDB) is compliance based and dependent on adequate use of the PAP device on a nightly basis in the home setting. It is important to distinguish between treatment efficacy and treatment effectiveness, as the effectiveness of treatment in the real-world setting is a better measure of residual disease burden. When adequate PAP adherence is defined as greater than 4 hours of nightly use, a high proportion of patients with OSA have been reported to be non-adherent to treatment.¹ This low partial adherence rate may leave patients exposed to high apnoea/hypopnoea burden with attendant chronic intermittent hypoxia and sleep fragmentation when therapy is not being used. This is of particular concern in patients with severe OSA who are at increased risk for fatal and non-fatal cardiovascular events.¹

The researchers developed the Effective AHI to more accurately quantify residual disease burden, as measured by AHI, by equaling the sum of apnoeas and hypopnoeas during the time the patient is using and not using PAP (PAP Off), divided by hours of total sleep time. Two of the specific aims of their research were to measure the Effective AHI in patients with severe OSA who varied widely in adherence to PAP therapy, and determine the optimal level of PAP use necessary to normalise Effective AHI values (AHI<5).   

Twenty-eight adult patients (75% men, age 51.4 ± 10.8 years [mean ± SD]) comprised the study sample. The mean Effective AHI of 18.3, was significantly lower than the mean Diagnostic AHI of 67.9 (P < 0.0001). All patients using PAP ≥ 6 h had an Effective AHI < 5. For patients using PAP < 6 h, Effective AHI scores < 5 only occurred in patients who slept in a non-supine position during PAP Off time; leaving 63.6% of patients with residual moderate-to-severe OSA.¹

This study concludes that significant disease burden, as objectively measured by the Effective AHI, may still exist in many patients with severe OSA in whom PAP therapy is not utilised for the entire sleep period. Knowledge of true Effective AHI could also provide the treating clinician with a very valuable tool to assess which specific therapy may provide the highest level of control of SDB, as measured by treatment related changes in the AHI. Further studies are needed however to determine how well the Effective AHI predicts important health outcomes such as sleepiness, quality of life, and incidence of cardiovascular events.¹

Reference:

1. Boyd SB, Upender R, Walters AS, Goodpaster L, Stanley JJ, Wang L, Chandrasekhar R. Effective apnea-hypopnea index (“Effective AHI”): a new measure of effectiveness for positive airway pressure therapy. SLEEP 2016;39(11):1961–1972.

Obstructive sleep apnoea (OSA) is more and more prevalent worldwide accompanying with high rates in morbidity and mortality. One of the principal treatments is CPAP but for some patients it brings several problems related to compliance and adherence to the equipment. On the other hand, obesity is highly linked to OSA and researchers have investigated that weight loss can help in treatment. For that reason a group of investigators of the Zagazig and Alex Universities in Egypt have assessed the effect of bariatric surgery on severe obstructive sleep apnoea patients not tolerating the CPAP therapy.

The study is a prospective single center observational study; it was done in the pulmonary rehabilitation center in association with the surgical department in Al-Amiri hospital, Ministry of Health, State of Kuwait in the period between June 2013 and July 2015. They included 22 patients documented to have morbid obesity (BMI > 40) and severe OSA with Apnoea Hypopnea Index (AHI) >30/h and not tolerating CPAP therapy, these patients were offered sleeve gastrectomy then were followed up for 12 months before another polysomnography was done to assess the presence of OSA and need for CPAP.

Results: The mean age of the patients was 37.2 ± 17.3 years, 13 males and 9 females. After sleeve gastrectomy and follow up for 12 months the body weight decreased from 135.6 ± 17.8 to 101.3 ± 7.6 kg m (p = 0.001), BMI dropped from 48.2 ± 7.3 to 35.9 ± 4.8 kg m/m2 (p = 0.001), mean AHI decreased from 55.8 ± 8.3 to 12.8 ± 11.3 attacks/hour of sleep (p = 0.001) and CPAP pressure needed to control OSA was decreased from 13.2 ± 2.3 to 8.2 ± 3.9 cm H2O (p = 0.001).

It is important to say that the value of SPO2 had an important improvement as well as the index of arousals which may prevent comorbidities related with these two aspects.

The conclusion the researchers came to was that for patients with a high BMI and AHI, sleeve gastrectomy could reduce the severity of OSA or the level of CPAP required for effective therapy, they also concluded that it could even be an alternative treatment option for patients in this cohort whom are not compliant to CPAP.

[1] H. Shaarawya, , Abdelrahman Sarhanb, A. EL Hawaryc. Assessment of the effect of bariatric surgery on severe obstructive sleep apnea patients not tolerating CPAP therapy. Egyptian Journal of Chest Diseases and Tuberculosis. Volume 65, Issue 3, July 2016, Pages 661–666