Demystifying End Tidal CO2 Bonnie Jo Grieve, MD, Dousman, Wisconsin, [email protected]
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Demystifying End Tidal CO2 Bonnie Jo Grieve, MD, Dousman, Wisconsin, [email protected] am a new post-polio ventilator user. lation. It can be measured in two ways. I I had polio at age 4 in 1953, was One way is measured by drawing arterial completely paralyzed and probably in blood gases (ABG). This measurement is an iron lung briefly. Now I have severe represented as PCO2 (the partial pressure kyphoscoliosis (front-to-back and side- of carbon dioxide, the relative concentra- to-side curvature of the spine) and tion of the gas in our blood). The other is new weakness. to measure CO2 at the end of exhalation Two years ago I was started on an S9 CPAP as we breathe air out, which is called End (ResMed) but was unable to breathe out Tidal CO2 (EtCO2). against the pressure, so was Measuring PCO2 by ABG involves drawing switched to a Respironics blood from an artery, usually the radial “The situation gets AVAPS BiPAP (Philips Respi- artery at the wrist or sometimes the ronics) initially with low span femoral artery in the groin, and lab anal- complicated for those settings. After a year of contin- ysis. Obtaining an EtCO2 measurement of us unable to respond ued awakenings with tachy- is painless, usually with a tiny cannula cardia, I upped the settings to (tube) placed under our masks, just in- adequately to our need high span, IPAP currently at side our nose or mouth, whichever we use 20 and EPAP 5, and have been to exhale, or in the exhalation port of our for oxygen.” sleeping through the night ventilator set up. The EtCO2 correlates ever since. with the PCO2 from our arterial blood, Every week brings new information but does not require any blood draw, just about neuromuscular hypoventilation. a small sample of the air we breathe out. In February 2013, IVUN hosted a phone The Role of Breathing conference featuring physiatrist Dr. John R. Bach and his recommendations re- Breathing accomplishes both bringing garding relying on noninvasive ventila- in oxygen and expelling CO2 as a waste tion (NIV) for as long as possible for most gas. The amount of breathing we do is neuromuscular ventilation needs. His usually determined by how much oxygen books discuss NIV, pulse oxygen moni- our chemoreceptors sense in our blood. toring, CoughAssist with manual thrusts If we breathe more, we take in more if necessary, and end tidal carbon dioxide oxygen but exhale more CO2, and our CO2 goes down. If we breathe less, our (CO2) monitoring for CO2 retention. This CO2 keeps being produced by our cells, raised questions about CO2 monitoring. but not enough is exhaled, so CO2 rises. Understanding CO2 The situation gets complicated for those Carbon dioxide is a byproduct of the of us unable to respond adequately to our metabolism of oxygen and glucose for need for oxygen. Neuromuscular deficits may be too extensive to take in sufficient producing energy. CO2 diffuses out of cells and into the blood in our lungs and air to expand enough alveoli to absorb diffusing into our alveoli before exha- continued on page 6 FROM AROUND THE NETWORK New Products Quattro™ Air full face mask from ResMed weighs only 3.3 ounces. The dual-wall Spring Air™ cushion provides more comfort at the bridge of the nose, while the cutout at the chin provides a better seal. Other features include flex-wing forehead support; comfortable headgear; and one-piece elbow, swivel and anti-asphyxia valve. Available in three sizes each for men and for women. www.resmed.com RespIn 11 HFCWO Bronchial Clearance System is a new high frequency chest-wall oscillation device from MedInnovation Technology Group, Inc. It uses a patented system Quattro™ Air of valves, electronic control and targeted pressure pistons to deliver pulsations directly to targeted areas of the chest to loosen secretions. It operates at a low background pressure for more comfortable treatment. www.medinnovationtechgrp.com Pompe Disease Gene Therapy Researchers at the University of Florida Health in Gainesville recently reported results from a clinical trial of gene therapy. The therapy improved respiratory function in individuals with Pompe disease, a rare inherited metabolic disease. It occurs in children who are born with mutations in a gene responsible for the production of an enzyme vital to converting glycogen in the body to glucose. The lack of the enzyme leads to an accumulation of glycogen in the muscle which leads to muscle weakness, affecting the ability to walk and Send product news to breathe. After a six-month follow-up, the gene therapy was deemed safe and shown to [email protected] increase the time the trial participants could spend breathing on their own without assisted ventilation. The results of the study were published in Human Gene Therapy. www.liebertpub.com/hum, www.worldpompe.org Ventilator Industry Report “Mechanical Ventilators: A Global Strategic Business Report,” recently released by Global Industry Analysts, Inc., provides a comprehensive review of trends, issues, strategic industry activities and profiles of major companies worldwide. The mechanical ventilators’ market is expected to reach $3.9 billion (USD) by 2018. The cost of the report is $4,950. For more information, go to www.strategyr.com/Mechanical_Ventilators_Market_Report.asp. Update on Virus Outbreaks Since the H7N9 avian virus outbreak in China at the end of March, the virus has infected 132 people and claimed 37 lives. Most of the H7N9 infections have involved poultry-to-human transmission, but the potential for an endemic spread due to transmission between humans exists. There is little to no human immunity to this new virus. A group of researchers at the University of Hong Kong has designed a diagnostic test with high specificity for the H7N9 virus that can be processed within three hours. continued on page 7 VENTILATOR-ASSISTED International Ventilator Users Network’s mission is to enhance the lives and LIVING independence of home mechanical ventilator users and polio survivors through education, advocacy, research and networking. June 2013 Vol. 27, No. 3 How to contact IVUN To be sure you receive email updates from PHI and ISSN 1066-534X Executive Director Joan L. Headley, MS IVUN, set your spam filters to allow messages [email protected] from [email protected] and [email protected]. Editor: Gayla Hoffman, [email protected] Moving? Change of address? 4207 Lindell Blvd., #110 Designer: Sheryl R. Rudy, Notify IVUN before you move by calling 314-534-0475 or [email protected] Saint Louis, MO 63108-2930 USA Phone: 314-534-0475 email [email protected], and tell us your old and new addresses. ©2013 Post-Polio Health International (PHI). Fax: 314-534-5070 Permission to reprint must be [email protected] Away temporarily? obtained from Post-Polio Health www.ventusers.org Send us your second address and dates you will be there International (PHI). and we’ll do our best to send your newsletter. Like us on Facebook. International Ventilator Users Network (IVUN) IVUN’s Fifth Educational Conference Call How Polio Survivors Can Avoid Tracheostomies Joan L. Headley, Executive Director, International Ventilator Users Network, St. Louis, Missouri ohn R. Bach, MD, Physical Medicine is most likely for the survivors of polio. J& Rehabilitation, University Hospital, The treatments are very different. For University of Medicine & Dentistry of lung issues, the solutions include bron- New Jersey, Newark, New Jersey, is in chodilators and oxygen. But, for muscle charge of the Center for Noninvasive weakness, the treatment is the use of Mechanical Ventilation Alternatives respiratory aids which include noninvasive and Pulmonary Rehabilitation and has ventilation and mechanical coughing aids. spoken and written If a patient has both extensively. His most problems, e.g., lung recent contribution “There are also some problems due to smok- to the literature is ing and neuromuscular “Management of people who never before weakness due to polio, a Patients with Neu- needed assisted ventilation decision may need to be romuscular Disease” made as to which is the by Hanley & Belfus until recently.” primary problem and (2003). treat it. Prior to his presentation on February 27th, Dr. Bach on breathing muscles: Inspiratory Dr. Bach submitted “Respiratory Muscle muscles assist with inhaling. Shortness Aids to Avert Respiratory Failure and of breath when lying flat (orthopnea) is Tracheostomy,” which can be found a sign of a weak diaphragm (an inspira- at www.ventusers.org/edu/ConfCall2013 tory muscle). Many polio survivors use Bach.pdf. His talk supported the prem- pillows to support their backs to prevent ise that “Polio survivors can virtually shortness of breath when they sleep, but ALWAYS avoid tracheostomies even if the best solution for weak inspiratory continuously (noninvasively) ventilator muscles is intermittent positive pressure dependent,” which he did by expanding ventilation (air under pressure when on several statements. inhaling) from a ventilator and via a nose Dr. Bach describes his patients: My first interface. It takes about 20 ml of water patients were those who used ventilators pressure to ventilate someone who has after having had polio. Then, I started severe muscle weakness. seeing patients who had used iron lungs Expiratory muscles (mostly the abdomi- but had been weaned from them but now nals) assist with coughing. If survivors needed to use noninvasive ventilation. get a cold, they may not complain of There are also some people who never shortness of breath but of anxiety and before needed assisted ventilation difficulty sleeping due to high blood until recently. carbon dioxide levels. Dr. Bach on the decision to use assisted It is not helpful to use CPAP and only ventilation: First, it should be determined minimally helpful to use bilevel devices if polio survivors are symptomatic for if breathing muscles are weak, because nocturnal underventilation.