History

Fact Explanation
Shortness of breath Severe shortness of breath can develop at rest, disturbs sleep and often interferes with conversations. Patient can't complete a sentence. Status asthmaticus is a reversible, recurrent, diffuse obstructive pulmonary disease resulted by airway inflammation and hyper-reactivity. Smooth muscle spasm, edema of the mucosa and mucous plugging causes airflow obstruction leading to hypercarbia and hypoxia. Status asthmaticus may progress from acute severe to life threatening form. The condition is reversible with aggressive treatment. [1,2,3]
Cough Usually occurs at night along with shortness of breath and wheeze. Often non productive despite of mucus obstruction of the airway. Cough-variant asthma is a type of asthma that doesn't often have other asthma symptoms. [1,2,4]
Wheeze Wheeze is a continuous, coarse, whistling sound produced in an obstructed respiratory airways during expiration. [4]
Restlessness This occurs due to brain hypoxia when exacerbation deteriorates further. [4]
Drowsiness This occurs due to brain hypoxia (PaO2 less than 60mmHg) when exacerbation deteriorates further. Patient may feel sleepy and confused as well. [1,4]
References
  1. HARDERN R. Oxygen saturation in adults with acute asthma.. Emergency Medicine Journal [online] 1996 January, 13(1):28-30 [viewed 12 May 2014] Available from: doi:10.1136/emj.13.1.28
  2. MCFADDEN E. R.. Acute Severe Asthma. Am J Respir Crit Care Med [online] 2003 October, 168(7):740-759 [viewed 12 May 2014] Available from: doi:10.1164/rccm.200208-902SO
  3. REES HA. Management of status asthmaticus. Postgrad Med J [online] 1967 Apr, 43(498):225-233 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2466299
  4. BRITISH THORACIC SOCIETY, SCOTTISH INTERCOLLEGIATE GUIDELINES NETWORK. British guideline on the management of asthma. Thorax [online] 2003 Feb:i1-94 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12653493

Examination

Fact Explanation
Use of accessory muscles Labored breathing against an obstructed airway is supported by accessory muscles such as sternocleidomastoid and the scalene muscles which help to increase the capacity inside the thoracic cavity. [1,2,3]
Recessions Sucking in of the skin around the ribs and the top of the sternum is due to labored breathing. Recession is a clinical sign of respiratory distress which occurs as increasingly negative intrathoracic pressures causes in drawing of part of the chest. They are visible subcostally and intercostally. [1,2]
Prolonged expiration and nasal flaring Air is trapped in the lower airway due to the obstruction. Therefore more effort is required to expel air from the lungs. This causes nasal flaring on inspiration. [1,2,3]
Tachypnoea Tachypnoea is the condition of rapid breathing. In adult humans at rest, tachypnea is indicated by a ventilatory rate greater than 20 breaths per minute. [1,3,4]
Rhonchi Rhonchi are continuous, low pitched sounds with a gurgling, snoring or rattle-like quality. It is more common during expiration and usually caused by secretion in bronchial airways. [1,2,4]
Tachycardia During an acute attack, there is no sufficient air entering the lung which in turn increase the heart rate under autonomic nervous stimulation. Tachycardia (heart rate >100/min) can be a sign of severity, but is also a side effect of beta agonist which is used in treatment. [1,2]
Silent chest As the disease becomes severe, air flow can dramatically decrease causing silent chest on auscultation while the patient is making severe respiratory effort. It is an ominous sign that indicates severe deterioration of the acute attack and needs immediate attention. Silent chest is commonly accompanied by hypercapnia (increased carbon dioxide levels in the blood) and acidosis, both of which are life- threatening. [1,2,4]
Altered level of consciousness This occurs due to brain hypoxia when exacerbation deteriorates further. [1]
Orthopnoea The airway size is smaller supine position exaggerating airway obstruction. Accessory muscles can be used more efficiently in erect position. Asthmatics cannot lay flat and prefers to sit up or stand. [1,2,3]
Cyanosis It is the appearance of a blue or purple discoloration of the skin or mucous membranes due to subcutaneous tissue having low oxygen saturation. [1,2,3]
Pulsus paradoxus During inspiration the increased negative pressure facilitates venous return and blood gets sequestered in Pulmonary circulation causing the blood pressure to fall.The normal fall in pressure is less than 10 mmH. When the drop is more than 10mm Hg, it is referred to as pulsus paradoxus. Severity of asthma can be assessed. [1]
Wheezing Wheeze is a continuous, coarse, whistling sound produced in an obstructed respiratory airways during expiration. However wheezing is a poor indicator of severity of the obstruction as It often increases as the obstruction resolves. It is the absence of wheezing that is important as "silent chest" indicates a life threatening condition with very severe airway limitation. [1,2,3,4]
References
  1. BRITISH THORACIC SOCIETY, SCOTTISH INTERCOLLEGIATE GUIDELINES NETWORK. British guideline on the management of asthma. Thorax [online] 2003 Feb:i1-94 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12653493
  2. RODRIGO GUSTAVO J.. Acute Asthma in Adults . Chest [online] 2004 March [viewed 13 May 2014] Available from: doi:10.1378/chest.125.3.1081
  3. TATHAM ME, GELLERT AR. The management of acute severe asthma. Postgrad Med J [online] 1985 Jul, 61(717):599-606 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418319
  4. CORBRIDGE,TC, J.B.HAll.The Assessment and Management of Adults with Status Asthmaticus, Am J Respir Crit Care Med [online],1995,151,1296-1316 [viewed 12 May 2014] Available from: http://medicine.uthscsa.edu/PulmonaryDiseases/ATSMeettheProfessor/OverviewandReviewsofStatusAsthmaticus/Corbridge%20and%20Hall%20Best%20Review%20Article%20on%20Status%20Asthmaticus.pdf

Differential Diagnoses

Fact Explanation
Foreign body aspiration Sudden onset of coughing, wheezing and decreased breathing sounds. All these may accompanied with hemoptysis, dyspnea, and chest pain. [1]
Pneumonia Gradual onset of fever with productive cough. Commonly bacterial in origin. Chest pain is of pleuritic type. Pneumonia responds to intravenous antibiotics. [2]
Congestive heart failure Congestive cardiac failure can be manifest as cough,Shortness of breath at rest, fatigue, weakness and fainting. Orthopnoea and paroxysmal nocturnal dyspnea are late signs. On examination there may be hepatomegaly, ankle oedema. [3]
Bronchiectasis This classically manifests with productive cough and daily mucopurulent sputum. Symptoms may last from months to years. Blood-streaked sputum or hemoptysis may also present. Dyspnea, pleuritic chest pain, wheezing, fever and weight loss are the other symptoms. [4]
Chronic obstructive lung disease This category basically includes chronic bronchitis and emphysema. Shortness of breath, cough, and sputum production are the main symptoms. [5]
References
  1. QURESHI A, BEHZADI A. Foreign-body aspiration in an adult Can J Surg [online] 2008 Jun, 51(3):E69-E70 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2496600
  2. MARSH DR, GILROY KE, VAN DE WEERDT R, WANSI E, QAZI S. Community case management of pneumonia: at a tipping point? Bull World Health Organ [online] 2008 May, 86(5):381-389 [viewed 12 May 2014] Available from: doi:10.2471/BLT.07.048462
  3. REDDY S, BAHL A, TALWAR KK. Congestive heart failure in Indians: How do we improve diagnosis & management? Indian J Med Res [online] 2010 Nov, 132(5):549-560 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3028953
  4. DAVIES G, WILSON R. Prophylactic antibiotic treatment of bronchiectasis with azithromycin Thorax [online] 2004 Jun, 59(6):540-541 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1747020
  5. LARATTA CR, VAN EEDEN S. Acute Exacerbation of Chronic Obstructive Pulmonary Disease: Cardiovascular Links. Biomed Res Int [online] 2014:528789 [viewed 13 May 2014] Available from: doi:10.1155/2014/528789

Investigations - for Diagnosis

Fact Explanation
Peak flow meter Peak flow meter measures peak expiratory flow rate (PEFR) which is essential in diagnosing and assessing the severity of asthma. It is readily available and reproducible. Peak expiratory flow (PEF) is the maximal flow achieved during the maximally forced expiration initiated at full inspiration, measured in liters per minute or in liters per second. In asthma, peak flow is low as a percentage of predicted value. In status asthmaticus, PEFR is between 35% - 50% of predicted in acute severe asthma and is below 35% of predicted in a life-threatening episode. [1,2]
pulse oximetry Provides a continuous oxygen saturation evaluation , which is of vital importance because hypoxia can be fatal in status asthmaticus. Treatment can be adjusted according to oxygen saturation. The aim of oxygen therapy is to maintain SpO2 (oxygen saturation) above 94%. [1,2,3]
Arterial blood gas (ABG) analysis Patients with SpO2 < 92% or with other features of life threatening asthma require ABG measurement. SpO2 < 92% is associated with a risk of hypercapnea. Which is not detected by pulse oximetry. So it is essential to do an ABG in such circumstances. Normal or raised CO2 levels are indicative of worsening asthma. [1,2,4]
Full blood count Neutrophilic leucocytosis is present in pulmonary infections. [1,2,5,6]
Chest X-ray This is important to exclude pneumonia, pneumothorax, pneumomediastinum or heart failure. Signs of chronic obstructive pulmonary disease can also be found out. Chest X-ray is also important in patient who do not respond to therapy. [1,2,5,6]
Electrocardiography The main ECG change is sinus tachycardia. But in patients who does not have co-existing heart disease right axis deviation, right ventricular hypertrophy, P pulmonale and ST segment or T wave abnormalities can be present. [1,2,3,6]
Spirometry Although this is an important test, spirometry is less commonly used in acute episodes. FEV1/FVC ratio represents the proportion of a person's vital capacity that they are able to expire in the first second of expiration. This value is below normal in asthma and is between 35% - 50% of predicted in acute severe asthma and is below 35% of predicted in a life-threatening episode. [1,3,6]
References
  1. HARDERN R. Oxygen saturation in adults with acute asthma.. Emergency Medicine Journal [online] 1996 January, 13(1):28-30 [viewed 12 May 2014] Available from: doi:10.1136/emj.13.1.28
  2. MCFADDEN E. R.. Acute Severe Asthma. Am J Respir Crit Care Med [online] 2003 October, 168(7):740-759 [viewed 12 May 2014] Available from: doi:10.1164/rccm.200208-902SO
  3. SUSAN,M. et al. Management of Acute Asthma Exacerbations, Am Fam Physician [online]. 2011 Jul 1,84(1), 40-47. [viewed 12 May 2014] Available from: http://www.aafp.org/afp/2011/0701/p40.html
  4. REES HA. Management of status asthmaticus. Postgrad Med J [online] 1967 Apr, 43(498):225-233 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2466299
  5. TATHAM ME, GELLERT AR. The management of acute severe asthma. Postgrad Med J [online] 1985 Jul, 61(717):599-606 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418319
  6. BRITISH THORACIC SOCIETY, SCOTTISH INTERCOLLEGIATE GUIDELINES NETWORK. British guideline on the management of asthma. Thorax [online] 2003 Feb:i1-94 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12653493

Management - General Measures

Fact Explanation
Fluid management Patients in status asthmaticus are inevitably dehydrated due to poor oral intake, tachypnea, and often emesis. The dehydration often causes a metabolic acidosis as well increasing their work of breathing. Rehydration prevents thickening of mucous secretions and begins to treat the metabolic acidosis. [1,2]
Correction of hypokalaemia This can be resulted from the beta agonist drug therapy. And it should be corrected with intravenous potassium chloride. [1]
Anitbiotics This is not routinely done. It is only indicated if there are evidences of an infection such as pneumonia. [1,3]
Positioning the patient The patient should be positioned in a way that ease the breathing with straightened airway. Sitting the patient up is preferred. [1,3]
Treatment setting In a case of life threatening asthma, the patient should be transferred to an emergency treatment unit. Other indications are altered consciousness, exhaustion and rising PCO2 despite treatment. [1,2,3]
References
  1. BRITISH THORACIC SOCIETY, SCOTTISH INTERCOLLEGIATE GUIDELINES NETWORK. British guideline on the management of asthma. Thorax [online] 2003 Feb:i1-94 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12653493
  2. REES HA. Management of status asthmaticus. Postgrad Med J [online] 1967 Apr, 43(498):225-233 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2466299
  3. TATHAM ME, GELLERT AR. The management of acute severe asthma. Postgrad Med J [online] 1985 Jul, 61(717):599-606 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418319

Management - Specific Treatments

Fact Explanation
Oxygen therapy Many patients with acute severe asthma are hypoxaemic, indicating oxygen therapy as essential. It can be administered via a nasal prone or face mask. Oxygen therapy can be easily titrated to maintain the patient’s oxygen saturation between 94 - 98% with continuous monitoring with of pulse oximetry. In significant hypoxemia with respiratory failure, tracheal intubation and mechanical ventilation are indicated. [1,2,3]
Beta-2 agonists The first line of therapy. Beta 2 agonists act on beta2-adrenergic receptor, thereby causing smooth muscle relaxation, resulting in dilation of bronchial passages. Salbutamol is given by a metered dose inhaler/spacer, one dose every 20 minutes or by wet nebulisation driven by oxygen. In acute asthma with life threatening features the nebulised route (oxygen-driven) is recommended. Continuous nebulisation of β2 agonists with an appropriate nebuliser may be more effective than bolus nebulisation in relieving acute asthma for patients with a poor response to initial therapy. There is no evidence for any difference in efficacy between salbutamol and terbutaline. The usual salbutamol dose is 5mg while terbutaline dose is 10mg orally. [1,2,4,5]
Anticholinergics nebulisation They block the neurotransmitter acetylcholine in the peripheral nervous system thereby causing smooth muscle relaxation, resulting in dilation of bronchial passages. Combining nebulised ipratropium bromide (0.5 mg) with a nebulised β2 agonist produces significantly greater bronchodilation than a β2 agonist alone. [1,2,3]
Oral steroids Steroids are the most important treatment for status asthmaticus. The anti inflammatory effect of steroids reduces the mucosal inflammation and secretions, clearing the air way. The usual dose is oral prednisolone at 1-2 mg/kg or prednisolone 40-50 mg daily. It should be continued for at least five days or until recovery. [1,2,3]
Intravenous hydrocortisone Parenteral hydrocortisone 400 mg daily (100 mg six-hourly) can be used as an alternative for oral prednisolone. [1,2,6]
Intravenous Aminophylline Aminophylline is a compound of the bronchodilator theophylline with ethylenediamine. It is a methylated xanthine derivative that causes bronchodilation. If IV aminophylline is given to patients on oral aminophylline or theophylline, blood levels should be checked. It should be administered as 5 mg/kg loading dose over 20 minutes and then an infusion of 0.5-0.7 mg/kg/hr. [1,2,3,4]
Intravenous magnesium sulphate Intravenous magnesium sulphate is considered if the patient does not respond to inhaled bronchodilator therapy and if further deteriorating to ƒƒ life threatening or near fatal asthma. ƒƒIV magnesium sulphate (1.2-2 g IV infusion over 20 minutes) should only be used following consultation with senior medical staff. [1,2,7]
Intravenous Beta-2 agonists Severe, refractory status asthmaticus may benefit from this agents. Nebulised bronchodilators should be continued while the patient is receiving intravenous bronchodilators. Once the patient is improving the intravenous infusion should be reduced before reducing the frequency of nebulised bronchodilators. [1,2,5,7]
Sedation In very small doses and under controlled and monitored settings. Lorazepam (0.5 or 1 mg IV) could be used for those who are anxious and already on regular therapy. [1]
Mechanical ventilation This is considered as a last treatment option in patients with apnea or respiratory arrest and with diminishing level of consciousness. Mechanical ventilation needs careful monitoring. The usual duration of mechanical ventilation is 72 hours, yet can be lengthen. Nasotracheal route is avoided. Intubation should be done before the crisis of respiratory arrest occurs. A suitable endotracheal tube should be selected. Lidocaine 1.5 mg/kg IV is given as premedication. Induction is achieved with Midazolam 1 mg IV q 2-3 min or Ketamine 1–2 mg/kg IV. A neuromuscular blocking agent, preferrably Rocuronium or Succinylcholine is used. [1,2,3,8]
References
  1. BRITISH THORACIC SOCIETY, SCOTTISH INTERCOLLEGIATE GUIDELINES NETWORK. British guideline on the management of asthma. Thorax [online] 2003 Feb:i1-94 [viewed 13 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12653493
  2. TATHAM ME, GELLERT AR. The management of acute severe asthma. Postgrad Med J [online] 1985 Jul, 61(717):599-606 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418319
  3. RODRIGO GUSTAVO J.. Acute Asthma in Adults . Chest [online] 2004 March [viewed 13 May 2014] Available from: doi:10.1378/chest.125.3.1081
  4. STATHER DAVID R, STEWART THOMAS E. . Crit Care [online] 2005 December [viewed 13 May 2014] Available from: doi:10.1186/cc3733
  5. REES HA. Management of status asthmaticus. Postgrad Med J [online] 1967 Apr, 43(498):225-233 [viewed 12 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2466299
  6. USAN,M. et al. Management of Acute Asthma Exacerbations, Am Fam Physician [online]. 2011 Jul 1,84(1), 40-47. [viewed 12 May 2014] Available from: http://www.aafp.org/afp/2011/0701/p40.html
  7. SELLERS W. F. S.. Inhaled and intravenous treatment in acute severe and life-threatening asthma. British Journal of Anaesthesia [online] December, 110(2):183-190 [viewed 12 May 2014] Available from: doi:10.1093/bja/aes444
  8. BRENNER B., CORBRIDGE T., KAZZI A.. Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure. Proceedings of the American Thoracic Society [online] December, 6(4):371-379 [viewed 12 May 2014] Available from: doi:10.1513/pats.P09ST4