Presentation on theme: "Acute severe bronchial asthma Presented by: Reem alsafar."— Presentation transcript:
Acute severe bronchial asthma Presented by: Reem alsafar.
Bronchial asthma: Chronic airflow limitation witch is usually reverses spontaneously or with treatment,due to airway hyper-responsiveness to a range of specific and nonspecific stimuli (e.g exercise,cold air) and inflammation of the bronchi (esonophils, lymphocytes, mast cells,neunt., associated edema, smooth muscle hypertrophy and hyperplasia, thickening of basement membrane,mucous plugging and epithelial damage. Chronic airflow limitation witch is usually reverses spontaneously or with treatment,due to airway hyper-responsiveness to a range of specific and nonspecific stimuli (e.g exercise,cold air) and inflammation of the bronchi (esonophils, lymphocytes, mast cells,neunt., associated edema, smooth muscle hypertrophy and hyperplasia, thickening of basement membrane,mucous plugging and epithelial damage.
Epidemiology: The prevalence of asthma is increasing in 2 nd decade of life with highest rates in New Zealand, Australia and UK, and lowest in china and Malaysia. Etiology: There are 2 major factors involved in the development of asthma: - atopy (production of large amount of IgE on exposure to small amount of common antigen wich can be idetified by skin prick reactions - non-atopy or intrinsic asthma (increased responsiveness of the airways of the lungs as measured by a fall in FEV1 to stimuli e.g: histamine, methacholine. Almost all asthmatic patients show some degree of atopy.
Pathogenesis: Is complex and not fully understood. It involves a number of cells,mediators,nerves and vascular leakage witch can be activated by several mechanism,of witch exposure to allergens is the most relevant. Precipitating factors: - genetic susceptibility: genetic contribution to asthma remains poorly defined,it possibly involves polygenic inheritance and genetic heterogenesity where different combinations of gens leads to asthma in different individuals. -environmental factors: house dust mites,pets, fungul spores,nitrogen and sulfer dioxide, grass and flower pollens and climate. -infections.-drugs. -smoking -emotions -exercise
Classification: %personal best PEF or FEV1 Night symptoms Day symptoms Diagnosis of asthma ≥80%.asympt. With normal LF bet. exacerbation <2 times per month No daily med. needed ≤2 times per week with brief exacerbations Mild intermitted <80% >2 times per month /exaceb. affect activity and sleep. >2 times per week, but not more than once aday Mild persistent >60-<80 >1 time per week Daily with exacerbation affect activity and sleep Moderate persistent ≤60% Frequent with freq. exacerbation continual Severe persistent
Severe acute asthma Is a medical emergency characterized by severe progressive asthmatic symptoms over a number of hours or days that must be recognized and treated immediately.
Presentation: acute breathlessness and wheeze, patients are usually extremely distressed, using accessory muscles of respiration,are hyper-inflated and tachypnoeic accompanied by tachycardia, pulsus paradoxus and sweating. In very severe cases central cyanosis occurs and airflow may have become so restrictive that rhonchi are no longer produced. The presence of silent chest and bradychardia in such patients is an ominous sign.
In the history: Ask about usual and recent treatment,previous acute episodes and their severity, have they been admitted to ITU. Other conditions in witch wheeze is prominent sign: Acute infective exacerbation of COPD, pulmonary oedema, URT obstruction, recurrent thromboembolism, tumor causing localized wheeze.
Immediate management Assess severity of the attack: In severe attack: -the patient is unable to complete sentences -RR>25 BPM. -PR >110 beat/min. -PEF<50%of predicted or best.
Start treatment immediately prior to investigation. -Sit up and give O2 in high dose 60%. -salbutamol 5 mg or terbutaline 10 mg nebulized in O2. -hydrocortisone 200 mg IV or prednisolone 30mg PO or both if very ill. -antibiotics if definite evidence of infection: Focal shadowing on chest x ray, purulent sputum -chest x ray to exclude pnumothorax or pneumonia.
If life threatening features are present: Which are: -PEF<33% of predicted or best. - silent chest, cyanosis feeble respiratory effort. -bradycardia or hypotention. -exhaustion, confusion or coma. -ABG: PaCO2 >5Pa (36mmHg),PaO2 5Pa (36mmHg),PaO2<8Pa(60mmHg),low pH <7.35.
-Add ipratropium 0.5mg to nebulized β- agonist. -Give aminophilline IV 250mg (5mg/kg) over 20 min. omit this bolus if patient is on oral theophlline but urgently check level of therapeutic. Alternatively,give salbutamol or terbutaline 0.25mg IV over 10 min.
Monitoring the effects of treatment. Monitoring the effects of treatment. -Repeat PEFR 15-30 min after initiating treatment and then pre and post β-agonist in hospital at least four times. - Pulse oximeter monitoring: maintain SaO2>92%. Check blood gases only if SPO2<92% or life threatening features. -consider repeat blood gases 2h after starting treatment. -daily U/E as steriods and salbutamol may result in hypoklaemia
Further management. Further management. If patient improving: -40-60% O2 + prednisolone 30-60mg/24h po. -Nebulized salbutamol every 4h. -Monitor peak flow and oxygen saturations.
If patient not improving after 15-30 minutes. If patient not improving after 15-30 minutes. -Continue 60% O2 and steroids. -Nebulized salbutamol, max every 15-30 min. -Ipratropium 0.5mg nebulized every 6h.
If patient still not improving. If patient still not improving. -Aminophylline infusion-adult: 500mcg/kg/h, in 10-16y 800mcg/kg/h. -Do levels if infusion lasts >24h. Alternatively, give salbutamol infusion, eg 3-20mcg/min. -If no improvement, or life-threatening features present, consider transfer to ITU. Patient must be accompanied by an anesthetist prepared for emergency intubation.
once patient improving once patient improving -Wean down and stop aminophylline over 12- 24h. -Reduce nebulized salbutamol and switch to - inhaled β-agonist. -Initiate inhaled steroids and stop oral steroids if possible. -Continue to monitor PEFR. Look for deterioration on reduced treatment and beware early morning dips in PEFR -Look for the cause of the acute exacerbation and admission.
Drugs used in acute asthma. Drugs used in acute asthma. Aminophylline: The amount of IV aminophylline may need altering according to the individual. Factors which may necessitate reduction of dose: Cardiac or liver failure, drugs which increase the half-life of aminophylline eg cimetidine, ciprofloxacin, erythromycin, propranolol, contraceptive steroids
Factors which may require to increase the dose: Smoking drugs which shorten the half-life, eg: phenytoin, carbamazepine, barbiturates, rifampicin. Aim for plasma concentration of 10-20mcg/mL (55-110 ml mol/L. serious toxicity (BP increase, arrhythmias, cardiac arrest) can occur at concentrations ≥25mcg/mL. Measure plasma K+. Salbutamol side effects: Tachycardia, arrhythmias, tremor, hypokalaemia.
On discharge, patients should have: On discharge, patients should have: -Been on discharge medication for 24h. -had inhaler technique checked. - Peak flow rate >75% predicated or best with diurnal variability 75% predicated or best with diurnal variability <25% steroid and bronchodilator therapy. -Own PEF meter and management plan. -GP appointment within 1 week. -respiratory clinic appointment within 4 weeks
What are the indications for mechanical ventilation with intermittent positive pressure ventilation? -Worsening hypoxia (PaO2 <8kPa) despite 60% inspired oxygen. -Hypercapnia (PaCO2 >6kPa). -Drowsiness.-Unconsciousness.
What are the indications for steroids in chronic asthma? -Sleep is disturbed by wheeze. -Morning tightness persists until midday. -Symptoms and peak expiratory flows - progressively deteriorate each day. -Maximum treatment with bronchodilators. -Emergency nebulizers are needed.
References: 1-Davidson`s Principles and Practice of Medicine, text book, 19 th edition. 2-Parveen Kumar and Michael Clark. Clinical Medicine text book, 5 th edition. 3-Oxford Hand Book of Clinical Medicine,4 th edition. 4-250 cases in clinical medicine, R.R.Baliga,3th edition. 5- http:/www.tsged.com/Newsletters/Asthma_Emergenci es. Htm. 6-Hospital In Patient Management of Acute Asthma Attacks,A National Clinical Guidelines recommended for use in Scotland by Scttish Intercollegiate Guidelines Network, Pilot Edition 1996