· Heliox is a mixture of helium and oxygen. Heliox can have different helium to oxygen ratios e.g. (80:20 heliox) & (70:30 heliox ) (Fink 2006).
· This gas mixture has a lower density due to helium having a low density. This reduces turbulence and airway resistance, reducing the work for breathing. This reduces respiratory muscle fatigue, improves gas exchange & gives more time to the standard therapeutic agents to perform their intended function: Fleisher, Ludwig & Henretig (2006).
· Acute asthma is a common disease.
In asthma the difficulty in breathing is due to the bronchospasm and airway inflammation. Thus, the treatment of acute asthma depends upon the reversal of these two abnormalities. The standard therapy for acute asthma includes bronchodilating agents and corticosteroids. Some studies have shown that, Heliox can be used to augment the affects of the standard therapeutic agents in acute asthma (Rodrigo GJ, Pollack CV, Rodrigo C, Rowe BH, 2001). Meanwhile others state that existing evidence does not provide support for the administration of helium-oxygen mixtures to ED patients with moderate to severe acute asthma.
At this time, heliox treatment does not have a role to play in the initial treatment of patients with acute asthma (Rodrigo GJ, Pollack CV, Rodrigo C, Rowe BH, 2001). Heliox must be administered with care and continuous monitoring should be done to avoid technical complications (Hurford , WE, Cheifetz, IM, 2007).
· Indications (Louisiana State University 2003):
Heliox can be used in the following settings:
1. Upper Airway Obstruction:
a. Viral & post-extubation croup ( Vorwerk C, Coats T.2010 )
c. Vocal cord paralysis
d. Upper airway masses, including tumors
2. Lower Airway Obstruction
c. Brochiolitis (Liet JM, Ducruet T, Gupta V, Cambonie G. 2010)
d. Bronchopulmonary dysplasia :
· Contraindications: There are no absolute contraindications for heliox (Louisiana State University 2003).
· Risks & hazards of Heliox Use (Fink 2006):
1. Delivery of Too Much Volume: If a ventilator not designed for Heliox use is being used & a higher volume than required is delivered there is a risk of volume induced injury, pressure induced injury & hypocarbia.
2. Delivery of Too Much or Too Little Bronchodilator: When a jet nebulizer is used a lower or higher than normal flow of heliox can, respectively, result delivery of a lower or higher dose of the bronchodilator .
3. Hypothermia: This is seen when heliox is being administered using a hood.
4. Anoxia: This can happen when the heliox administered has Oxygen< 21%.
5. Liability with Heliox Devices: This can be minimized using devices that are designed
for heliox administration e.g. Regulators, Flow meters, Analyzers, Monitors,
Nebulizer & Ventilators.
· Hence some studies show that use of heliox can effectively reduce the turbulent flow and resistance to airflow in cases of airway obstruction e.g. acute asthma. On the contrary, other studies are much more skeptical regarding the use of heliox especially in initial management of acute asthma. Predominantly though it has been stated that heliox can be useful in management of patients with airway obstruction. Heliox administration can be tricky and it is important for clinicians and paramedics to understand the way heliox works especially its effect on different devices and patients. The use of FDA approved devices and elimination of jury rigged devices can go a long way in making heliox administration safe resulting in its increased role in patient care (Fink 2006).
· In a pre-hospital hyperventilating adult re-breathing of one’s own expired air can provide relief (Brouhard 2008). A paramedic should closely monitor patients doing such breathing exercises e.g. breathing into a paper bag as hypoxemia can result (Callaham M 1989) (Chin K, Ohi M, Kuno K 1992). Thus in hyperventilating adults re-breathing of one’s own expired air is not a safe option.
· The general consensus is that in correctly diagnosed cases of hyperventilation, re-breathing of expired air can be beneficial provided it is done in a semi-closed system with adequate ventilation to prevent hypoxia (Brouhard 2008).
· Hyperventilation is defined as ventilation in excess of that required to maintain normal arterial blood partial pressure of oxygen & partial pressure of carbon-di-oxide (Fleisher, Ludwig & Henretig (2006)).
· Hyperventilation syndrome is mostly seen in anxiety attacks. It is a psychological and emotional condition that causes patients to breathe too much (Nardi AE, Freire RC, Zin WA 2009).
· The increased rate and depth of breathing results in increased expulsion of CO2 in expired air. CO2 is essential in the maintenance of pH in our blood. Thus CO2 loss in hyperventilating patients results in altering of their blood pH(Fleisher, Ludwig & Henretig (2006)).
· The resulting respiratory alkalosis abnormally raises the blood pH. When sufficient amounts of CO2 have left the blood the patient may experience, numbness, later muscular cramps ensue (Brouhard 2008).
· Patients have traditionally been told to breathe their own expired air e.g. breathing in a paper bag. The theory behind this is that expired air is richer in CO2 and its inhalation can help raise the blood partial pressure of CO2 back to normal. Although some studies have shown that breathing into a paper bag can be beneficial other studies have shown the benefits are psychological (van den Hout MA, Boek C, van der Molen GM, Jansen A, Griez E 1988).
· The risks of paper bag breathing certainly outweigh benefits, especially once a paramedic misdiagnoses a heart attack or asthma (Wiwanitkit V 2010) as hyperventilation syndrome. The resultant hypoxemia due to continued breathing of expired air can be life threatening.
· Furthermore, some studies have shown that re-breathing air rich in CO2 can itself induce a panic attack in an already hyperventilating patient exacerbating the initial complain (Colasanti A, Salamon E, Schruers K, van Diest R, van Duinen M, Griez EJ 2008) & (Rassovsky Y, Kushner MG 2003).
· There are much safer options available for management of hyperventilation. These include reassurance, breathing exercises & calming the patient down. When correctly applied these can effectively control hyperventilation in adults.
· Croup; also known as larygotracheobronchitis, is a viral infection involving larynx & may extend into the trachea and bronchi (Fleisher, Ludwig & Henretig (2006)).pg 803
· 1.2% of healthy term infants in pediatric practice develop croup (Fleisher, Ludwig & Henretig (2006)).
· Causative organisms: Parainfluenza virus (60%), influenza, measles, respiratory syncytial virus (RSV). (Rihkanen H, Rönkkö E, Nieminen T, Komsi KL, Räty R, Saxen H, Ziegler T, Roivainen M, Söderlund-Venermo M, Beng AL, Hovi T, Pitkäranta A 2008), coronavirus (van der Hoek L, Sure K, Ihorst G, Stang A, Pyrc K, Jebbink MF, Petersen G, Forster J, Berkhout B, Uberla K 2005).
· Croup most commonly develops in winter months in infants between the ages of months to 3 years.
· Clinical manifestations: fever (ranges from 100.4 F to 102.2 F),tachycardia, tachypnea, coryza, signs of upper respiratory obstruction, inspiratory stridor is seen in mild cases resulting in barking cough, child is unable to maintain adequate oral intake. In more serious cases rhonchi and wheezes are heard on auscultation. Suprasternal & substernal retractions are often seen. Steeple sign is seen on neck radiograph.
· Croup can be complicated by dehydration and upper airway obstruction. In these cases signs of impending respiratory failure e.g. Restlessness, agitation, irrational behaviour, decreased level of consciousness, hypotonia, cyanosis and marked pallor can be seen. In these cases use of scoring system for assessing the severity of croup can be useful. The child must be given high-flow oxygen via a facemask, with further nebulised adrenaline & tracheal intubation must be carried out. Once airway is secured systemic corticosteroids should be administered (Fitzgerald, Da, Henry,Ak, 2003).
· Epiglotitis; is an inflammatory condition confined to supra-glottic structures i.e. epiglottis, eriepiglottic folds and arytenoids. There is marked edema of these structures which may obstruct airway.
· Etiology: Usually affects children between the ages of 2 to 7 years. H.influenzae B is the most common causative agent in children. In the H influenzae type b vaccine era, acute epiglottitis in children has almost disappeared (Guldfred LA, Lyhne D, Becker BC 2008). Atypical organisms e.g. Candida albicans can cause epiglottitis in immune compromised adolescents (Sharma, Niraj MD, MPH; Berman, David M. DO, MS; Scott, Gwendolyn B. MD; Josephson, Gary MD 2005).
· Clinical manifestations: The onset of symptoms is sudden. Dyspnea and stridor are the main symptoms in children, these progress rapidly and can be fatal if not relieved. Fever up to 104F is seen.
· Pre hospital management: Maintain patency of airway and administer oxygen using a face mask or blow by technique. Use parent or guardian to perform this task to prevent the child from getting anxious. If the airway becomes obstructed, two-rescuer bag-valve-mask ventilations should be used. Intubation should be done as the last resort (PB WORKS 2009).
· Bronchiolitis: This is a contagious respiratory infection in children which is characterized by wheezing. Most commonly it happens in winter and mostly affects children between the ages of 2 to 8 months.
· Etiology: It is most commonly caused by RSV (González de Dios J, Ochoa Sangrador C; Grupo de Revisión, del Proyecto aBREVIADo (BRonquiolitis-Estudio de Variabilidad, Idoneidad y ADecuación) 2010), but other viruses i.e. PIV. In rare cases this disease can be caused by M.pneumoniae. Not breast feeding, exposure to cigarette smoke and the deficiency of VitA, D were the significant risk factors contributed to the RSV bronchiolitis (Tian M, Zhao DY, Wen GY, Shi SY 2009).
· Clinical manifestations: The initial symptoms which last a couple of days include, runny nose and mild cough. Tachypnea, severe dyspnea, nasal flaring, retractions, wheezing hypoxemia & apnea may follow. The child maybe febrile and dehydrated (Virtual Pediatric Hospital 2002).
· Pre hospital management: Asthma should be ruled out by asking about prior similar episodes. Then administer high concentration, high flow oxygen by face mask and continuously reassess. Ventilatory support may be necessary if signs of distress turn to signs of failure (Georgia Emergency Medical Services for Children 2000).
· Acute severe asthma is characterized by a bronchospasm refractory to outpatient therapy (Wall 2006).
· Ventilatory assistance is critical. Both noninvasive and invasive techniques are available (McFadden, ER 2003).
· Initial management :
· Oxygen therapy busing a tight fitting facemask (60%) (Gupta D, Nath A, Agarwal R, Behera D 2010).
· Nebulised salbutamol 2.5 +/- 0.5mg ipratropium (Lanes SF, Garrett JE, Wentworth CE 3rd, Fitzgerald JM, Karpel JP 1999).
· Oxygen therapy by tight fitting facemask (60%). http://www.ncbi.nlm.nih.gov/pubmed/20420722
· Nebulised salbutamol 2.5 +/- 0.5mg ipratropium*
· Glucocorticoid therapy i.e. prednisolone 30-60 mg should be started orally. Or, hydrocortisone 200mg intra-venous (Manser R, Reid D, Abramson MJ 2010).
· A chest X-ray to exclude pneumothorax
· Urgent blood gas
· Reassess in 15 min or if life-threatening features appear
· Consider i.v. aminophylline if life-threatening features or fails to improve after 15-30 minutes (Mitra AAD, Bassler D, Watts K, Lasserson TJ, Ducharme FM 2010).
· Ambulances equipped with nebulised bronchodilators provide the optimal mode of transport to hospital for patients with acute asthma (A Simpson, S Matusiewicz, P Brown, I McCall, J Innes, A Greening, and G Crompton 2000).
· Late management:The patient is removed from the nebulizer to usual inhaled device. Patient is discharged only when PEFR ‘normalised’ (80-90% of their best) without dipping. They should also be discharged on high-dose inhaled glucocorticoid, which should continue, until they are reviewed in clinic. The latter is important in preventing early relapse. Ambulances equipped with nebulised bronchodilators provide the optimal mode of transport to hospital for patients suffering from acute asthma.
· Lateral chest thrusts have no significant role in management of acute severe asthma patient .These are used in cases of choking (First Aid International 2002), but some medical authorities do not recommend their use even in cases of choking (Australian Resuscitation Council 2006).
§ James B Fink JUNE 2006 Opportunities and Risks of Using Heliox in Your Clinical Practice RESPIRATORY CARE VOL 51 NO 6 p.652
§ Fleisher, GR, Ludwig, S & Henretig, FM 2006, Textbook of pediatric emergency medicine, 5th edn, Lippincott, Wiliams &Wilkins,Philedalphia.
§ Rodrigo GJ, Pollack CV, Rodrigo C, Rowe BH, 2001. ‘Heliox for non-intubated acute asthma patients’., viewed 14th May 2010, < http://www2.cochrane.org/reviews/en/ab002884.html>
§ Hurford , WE, Cheifetz, IM,2007, ‘Respiratory controversies in the critical care setting. Should heliox be used for mechanically ventilated patients?’, Respiratory care, vol.52, no.5, pp 582-91, viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/17484790>
§ Louisiana State University 2003, Heliox Therapy, Louisiana State University, viewed 14th May 2010, < http://www.sh.lsuhsc.edu/cps/pandp/8.5.pdf>
§ Vorwerk C, Coats T.2010, ‘Heliox for croup in children’, Cochrane Database of Systematic Reviews, viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/20166089 >
§ Liet JM, Ducruet T, Gupta V, Cambonie G. 2010 ‘Heliox inhalation therapy for bronchiolitis in infants’, Cochrane Database Syst Rev, viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/20393951>
§ Brouhard, R, 2008, Can I treat hyperventilation syndrome by breathing into a paper bag?, About.com, viewed 14th May 2010, <http://firstaid.about.com/od/shortnessofbreat1/f/07_paper_bags.htm>
§ Fleisher, GR, Ludwig, S & Henretig, FM 2006,’Behavourial Emergencies’, Textbook of pediatric emergency medicine, 5th edn, Lippincott, Wiliams &Wilkins,Philedalphia.
§ Callaham M, 1989, ‘Hypoxic hazards of traditional paper bag rebreathing in hyperventilating patients’,, vol 18, no.(6), pp 622-8, viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/2499228 >
§ Van den Hout MA, Boek C, van der Molen GM, Jansen A, Griez E, 1988, ‘Rebreathing to cope with hyperventilation: experimental tests of the paper bag method’, J Behav Med. Vol 11 no (3) pp 303-10. viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/3139884>
§ Chin K, Ohi M, Kuno K 1992, Hyperventilation syndrome, Nihon Kyobu Shikkan Gakkai Zasshi.vol 30 Suppl:147-53. viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/1306218>
§ Wiwanitkit V, 2010, ‘Acute exacerbation of asthma complicated by hyperventilation in emergency department’. J Asthma. Vol 47 no.(2) pp 224-5. viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/20170334>
§ Colasanti A, Salamon E, Schruers K, van Diest R, van Duinen M, Griez EJ 2008, ‘Carbon dioxide-induced emotion and respiratory symptoms in healthy volunteers’. Neuropsychopharmacology. Vol 33 no (13) pp 3103-10. viewed 14th May 2010, http://www.ncbi.nlm.nih.gov/pubmed/18354390
§ Nardi AE, Freire RC, Zin WA 2009 , ‘Panic disorder and control of breathing’, Respir Physiol Neurobiol. Vol 167 no (1) pp 133-43. viewed 14th May 2010, http://www.ncbi.nlm.nih.gov/pubmed/18707030
§ Rassovsky Y, Kushner MG 2003, ‘Carbon dioxide in the study of panic disorder: issues of definition, methodology, and outcome’, J Anxiety Disord. Vol 17 no (1) pp 1-32. viewed 14th May 2010, < http://www.ncbi.nlm.nih.gov/pubmed/12464286>
§ Fleisher, GR, Ludwig, S & Henretig, FM 2006,’Infectious disease emergengies’ Textbook of pediatric emergency medicine, 5th edn, Lippincott, Wiliams &Wilkins,Philedalphia.
§ Rihkanen H, Rönkkö E, Nieminen T, Komsi KL, Räty R, Saxen H, Ziegler T, Roivainen M, Söderlund-Venermo M, Beng AL, Hovi T, Pitkäranta A 2008, ‘Respiratory viruses in laryngeal croup of young children’. J Pediatr. Vol 152 no (5) pp 661-5, viewed 14th May 2010,< http://www.ncbi.nlm.nih.gov/pubmed/18410770>
§ van der Hoek L, Sure K, Ihorst G, Stang A, Pyrc K, Jebbink MF, Petersen G, Forster J, Berkhout B, Uberla K 2005. ‘Croup is associated with the novel coronavirus NL63’ PLoS Med. vol 2 no (8) pg 24o,viewed on 14th May 2010 http://www.ncbi.nlm.nih.gov/pubmed/16104827
§ Fitzgerald, DA, Henry,AK, 2003 ‘Croup: assessment and evidence-based management’, MJA 2003, Vol 179 no (7) pp 372-377, viewed on 14th May 2010, < http://www.mja.com.au/public/issues/179_07_061003/fit10207_fm.html>
§ Guldfred LA, Lyhne D, Becker BC 2008, ‘ Acute epiglottitis: epidemiology, clinical presentation, management and outcome’. J Laryngol Otol. Vol 122 no (8) pp 818-23, viewed on 14th May 2010, http://www.ncbi.nlm.nih.gov/pubmed/17892608
§ Sharma, Niraj MD, MPH; Berman, David M. DO, MS; Scott, Gwendolyn B. MD; Josephson, Gary MD 2005, ‘Candida Epiglottitis in an Adolescent with Acquired Immunodeficiency Syndrome’, The Pediatric Infectious Disease Journal: Volume 24 – Issue 1 – pp 91-92, viewed on 14th May 2010, < http://journals.lww.com/pidj/Abstract/2005/01000/Candida_Epiglottitis_in_an_Adolescent_with.21.aspx>
§ PB WORKS 2009, ‘Epiglotittis’ , PB WORKS, viewed on 14th May 2010, < http://mstcparamedic.pbworks.com/Epiglottitis>
§ González de Dios J, Ochoa Sangrador C; Grupo de Revisión, del Proyecto aBREVIADo (BRonquiolitis-Estudio de Variabilidad, Idoneidad y ADecuación) 2010, ‘Consensus conference on acute bronchiolitis (v): prevention of acute bronchiolitis. Review of scientific evidence’ An Pediatr (Barc).vol 72 no (5) pp 353.e1-353.e26, http://www.ncbi.nlm.nih.gov/pubmed/20457017
§ Tian M, Zhao DY, Wen GY, Shi SY 2009, ‘The correlation factor about respiratory syncytial virus bronchiolitis and post-bronchiolitis wheezing in infant’, Zhonghua Shi Yan He Lin Chuang Bing Du Xue Za Zhi. Vol 23 no (5) pp 371-4,viewed 14th May 2010, http://www.ncbi.nlm.nih.gov/pubmed/20387490
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§ Gupta D, Nath A, Agarwal R, Behera D 2010, ‘A prospective randomized controlled trial on the efficacy of noninvasive ventilation in severe acute asthma’, Respir Care, Vol 55 no (5) pp 536-43, viewed 14th May 2010, http://www.ncbi.nlm.nih.gov/pubmed/20420722
§ Lanes SF, Garrett JE, Wentworth CE 3rd, Fitzgerald JM, Karpel JP 1999, ‘The effect of adding ipratropium bromide to salbutamol in the treatment of acute asthma: a pooled analysis of three trials’, Chest.Vol 114 no (2) pp 365-72, viewed 14th May 2010,< http://www.ncbi.nlm.nih.gov/pubmed/9726716>
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§ A Simpson, S Matusiewicz, P Brown, I McCall, J Innes, A Greening, and G Crompton 2000, ‘Emergency pre-hospital management of patients admitted with acute asthma’, Thorax, vol 55 no(2) pp 97–101,viewed on 14th May 2010, < http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1745682/>
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