PowerPoint Presentation

Respiratory Emergencies

Jessica Owen, CCRN

Anatomy

The cells of the human body require a constant stream of oxygen to stay alive. The respiratory system provides oxygen to the bodys cells while removing carbon dioxide, a waste product that can be lethal if allowed to accumulate. The Upper respiratory tract is composed of the nasal cavity, the oral cavity, the pharynx, and the larynx. The nose and nasal cavity form the main external opening for the respiratory system. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs. Hairs and mucus lining the nasal cavity help to trap dust, mold, pollen and other environmental contaminants before they can reach the inner portions of the body. Air exiting the body through the nose returns moisture and heat to the nasal cavity before being exhaled into the environment. the oral cavity, is the secondary external opening for the respiratory tract. Most normal breathing takes place through the nasal cavity, but the oral cavity can be used to supplement or replace the nasal cavitys functions when needed. Because the pathway of air entering the body from the mouth is shorter than the pathway for air entering from the nose, the mouth does not warm and moisturize the air entering the lungs as well as the nasal cavity. The pharynx is a muscular funnel that extends from the posterior end of the nasal cavity to the superior end of the esophagus and larynx. The pharynx is divided into 3 regions: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the superior region of the pharynx found in the posterior of the nasal cavity. Inhaled air from the nasal cavity passes into the nasopharynx and descends through the oropharynx, located in the posterior of the oral cavity. Air inhaled through the oral cavity enters the pharynx at the oropharynx. The inhaled air then descends into the laryngopharynx, where it is diverted into the opening of the larynx by the epiglottis. The epiglottis is a flap of elastic cartilage that acts as a switch between the trachea and the esophagus. Because the pharynx is also used to swallow food, the epiglottis ensures that air passes into the trachea by covering the opening to the esophagus. During the process of swallowing, the epiglottis moves to cover the trachea to ensure that food enters the esophagus and to prevent choking. The larynx, also known as the voice box, is a short section of the airway that connects the laryngopharynx and the trachea. The larynx is located in the anterior portion of the neck, just inferior to the hyoid bone and superior to the trachea. Several cartilage structures make up the larynx and give it its structure. The epiglottis is one of the cartilage pieces of the larynx and serves as the cover of the larynx during swallowing. Inferior to the epiglottis is the thyroid cartilage, which is often referred to as the Adams apple as it is most commonly enlarged and visible in adult males. The thyroid holds open the anterior end of the larynx and protects the vocal folds. Inferior to the thyroid cartilage is the ring-shaped cricoid cartilage which holds the larynx open and supports its posterior end. In addition to cartilage, the larynx contains special structures known as vocal folds, which allow the body to produce the sounds of speech. 2Anatomy

Lower respiratory tract: Composed of the trachea, the lungs, and all segments of the bronchial tree (including the alveoli).The trachea is a 5-inch long tube made of C-shaped hyaline cartilage rings. The trachea connects the larynx to the bronchi and allows air to pass through the neck and into the thorax. At the inferior end of the trachea, the airway splits into left and right branches known as the primary bronchi. The left and right bronchi run into each lung before branching off into smaller secondary bronchi. The secondary bronchi carry air into the lobes of the lungs2 in the left lung and 3 in the right lung. The secondary bronchi in turn split into many smaller tertiary bronchi within each lobe. The tertiary bronchi split into many smaller bronchioles that spread throughout the lungs. Each bronchiole further splits into many smaller branches less than a millimeter in diameter called terminal bronchioles. Finally, the millions of tiny terminal bronchioles conduct air to the alveoli of the lungs. 3Physiology

Inspiration Active process Chest cavity expands Intrathoracic pressure falls Air flows in until pressure equalizesExpiration Passive process Chest cavity size decreases Intrathoracic pressure rises Air flows out until pressure equalizesPulmonary VentilationPulmonary ventilation is the process of moving air into and out of the lungs to facilitate gas exchange. The respiratory system uses both a negative pressure system and the contraction of muscles to achieve pulmonary ventilation. The negative pressure system of the respiratory system involves the establishment of a negative pressure gradient between the alveoli and the external atmosphere. The pleural membrane seals the lungs and maintains the lungs at a pressure slightly below that of the atmosphere when the lungs are at rest. This results in air following the pressure gradient and passively filling the lungs at rest. As the lungs fill with air, the pressure within the lungs rises until it matches the atmospheric pressure. At this point, more air can be inhaled by the contraction of the diaphragm and the external intercostal muscles, increasing the volume of the thorax and reducing the pressure of the lungs below that of the atmosphere again.

To exhale air, the diaphragm and external intercostal muscles relax while the internal intercostal muscles contract to reduce the volume of the thorax and increase the pressure within the thoracic cavity. The pressure gradient is now reversed, resulting in the exhalation of air until the pressures inside the lungs and outside of the body are equal. At this point, the elastic nature of the lungs causes them to recoil back to their resting volume, restoring the negative pressure gradient present during inhalation.4Physiology

External RespirationExternal respiration is the exchange of gases between the air filling the alveoli and the blood in the capillaries surrounding the walls of the alveoli. Air entering the lungs from the atmosphere has a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than does the blood in the capillaries. The difference in partial pressures causes the gases to diffuse passively along their pressure gradients from high to low pressure through the simple squamous epithelium lining of the alveoli. The net result of external respiration is the movement of oxygen from the air into the blood and the movement of carbon dioxide from the blood into the air. The oxygen can then be transported to the bodys tissues while carbon dioxide is released into the atmosphere during exhalation.5Developmental Variances of a Childs Respiratory System

Developmental Variances of a Childs Respiratory SystemDuring infancy and early childhood the intercostal muscles cannot effectively lift the chest wall to increase intrathoracic volume and compensate for loss of diaphragm motion. 7Adequate Breathing

Normal rate and depthRegular breathing pattern.Normal breath sounds on both sides of lungs.Equal chest rise and fall.Pink, warm, dry skin.Under normal resting conditions, the body maintains a quiet breathing rate and depth called eupnea. Eupnea is maintained until the bodys demand for oxygen and production of carbon dioxide rises due to greater exertion. Autonomic chemoreceptors in the body monitor the partial pressures of oxygen and carbon dioxide in the blood and send signals to the respiratory center of the brain stem. The respiratory center then adjusts the rate and depth of breathing to return the blood to its normal levels of gas partial pressures.3 Normal Breath Sounds: Bronchial, Bronchovesicular, and VesicularBronchial sounds are present over the large airways in the anterior chest near the second and third intercostal spaces. Bronchial sounds are loud and high in pitch with a short pause between inspiration and expiration; expiratory sounds last longer than inspiratory sounds.Bronchovesicular sounds are heard in the posterior chest between the scapulae and in the center part of the anterior chest. Bronchovesicular sounds are softer than bronchial sounds, but have a tubular quality. Bronchovesicular sounds are about equal during inspiration and expiration.Vesicular sounds are soft, blowing, or rustling sounds normally heard throughout most of the lung fields. Vesicular sounds are normally heard throughout inspiration.8Inadequate BreathingBreathing rate < 12 or > 20

Shallow or irregular respirations

Unequal chest expansion

Decreased or absent lung sounds

Accessory muscle usage

Pale or cyanotic skin color

Cool, clammy skin appearance Pediatric NoteNormal Respiratory Rates by AgeAgeBreaths/minInfant (< 1 year)30 to 60Toddler (1 to 3 years)24 to 40Preschooler (4 to 5 years)22 to 34School Age (6 to 12 years)18 to 30Adolescent (13 to 18 years)12 to 16A consistent respiratory rate of less than 10 or more than 60 breaths/min in a child of any age is abnormal and suggests the presence of a potentially serious problem.

10Obstructive PathophysiologyTongueForeign body obstructionAnaphylaxis & AngioedemaFacial trauma and inhalation injuries (burns)Epiglottitis and CroupAspirationRestrictive PathophysiologyAsthmaCOPDDiffusion PathophysiologyPulmonary Edema: left-sided heart failure, toxic inhalations, near drowningPneumoniaPulmonary Embolism: blood clots, amniotic fluid, fat embolismVentilation PathophysiologyTrauma: rib fractures, flail chest, spinal cord injuriesPneumothorax & HemothoraxDiaphragmatic herniaPleural effusionMorbid obesityNeurological/muscular diseases: polio, MD, myasthenia gravisControl System PathophysiologyHead traumaCVADepressant drug toxicity: narcotics, sedative-hypnotics, ethyl alcoholAcute Respiratory Failure

OLDSCHOOLNEWSCHOOLAcute Respiratory FailureOld SchoolType IHypocapnic FailureDecreased oxygen level with a normal or low CO

Type IIHypercapnic FailureDecreased oxygen level with a high CO level Ventilation Perfusion ImbalanceRespiratory Mechanical PerformancePulmonary EdemaPulmonary EmbolismAspiration PneumoniaAsthmaARDSDrug OverdoseCOPDCVASpinal Cord InjuryMS: ALS, GB, MGPneumothoraxHypophosphatemiaAcute Respiratory FailureNew SchoolV/Q Mismatch

ShuntVentilation Perfusion ImbalanceNo Contact Between Blood and AlveoliCOPDAsthmaAtelectasisPulmonary EdemaPulmonary EmbolismAspiration PneumoniaARDSInitial AssessmentInitial Impression:Mental statusRespiratory rate and effortIf not responsive and not breathing or no normal breathing GET HELP!With infants & children, if arrest is unwitnessed perform 2 minutes of CPR before leaving.Pulse (rate & character) If no pulse start compressions and breaths (30:2) with 2 rescuers children & infant (15:2)If pulse but not breathing adequately, open the airway a perform rescue breathing.

Rescue BreathingRescue Breathing for AdultsRescue Breathing for Infants and ChildrenGive 1 breath every 5 to 6 seconds (about 10 to 12 breaths per minute).Give 1 breath every 3 to 5 seconds (about 12 to 20 breaths per minute).Give each breath in 1 second.Each breath should result in visible chest rise.Check pulse about every 2 minutes.Focused AssessmentSigns and symptomsAllergies MedicationsPertinent past medical historyLast meal or intakeEvents leading to symptomsFocused Assessment

Crackles (Rales) CHFPneumonia

Wheezing or RhonchiPneumoniaAspiration COPD Asthma

StridorFBAO Croup Anaphylaxis EpiglottitisAirway burn

Watch for critical signs: JVD, tracheal deviation, paradoxical chest movement. PlanHelp (?) Rapid Response vs. Code BluePut patient in position of comfort.Oxygen. Assist with medications.Calm and reassure.Minimize patient movement.Higher level of care.

Golden Rules

If you are thinking about giving O2, then give it!

If you cant tell whether a patient is breathing adequately, then they arent!

If youre thinking about assisting a patients breathing, you probably should be!

When a patient quits fighting it does not mean that they are getting better!

Case StudyA 93 year old woman with dementia became cyanotic and apneic during Thanksgiving dinner at her family residence. The Heimlich maneuver was performed by family and the aspirated material was retrieved, which was recognized as two pieces of turkey. The patient had continued respiratory distress and was immediately brought to the emergency department, where her oxygen saturation was 93% on 10 liters/minute of oxygen via nasal cannula. A chest radiograph showed a collapsed left lower lobe, and emergency bronchoscopy removed two pieces of food stuff from the left main stem bronchus. She promptly recovered and was discharged two days later, with a swallowing study recommended as an outpatient.

Two tan/white, firm, irregular shaped soft tissues were retrieved via bronchoscopy. Microscopically, sections showed degenerated skeletal muscle admixed with adipose tissue. Given the clinical scenario, the gross and microscopic appearances of the specimen were felt to be consistent with the aspiration of turkey.25Foreign Body Airway Obstruction

Obstruction may result from head position, tongue, aspiration, or foreign body.Be prepared to treat quickly and aggressively.If you suspect a complete obstruction for a conscious victim, use manual technique appropriate for age.< 1 year: Give 5 back slaps followed by 5 chest thrusts>1 year: Give abdominal thrustsIf victim becomes unresponsive, start CPR, beginning with chest compressions (even if pulse is palpable. Before you deliver breaths, look into the mouth. If foreign body is visible and easily removable, remove it. Do not perform a blind finger sweep!Case StudyA 6-year-old male presents conscious, alert and oriented, sitting up in bed in a sniffing position and complaining of a sore throat. He has a strong and rapid radial pulse, and his respiratory rate is normal, but you note inspiratory stridor with each breath. His skin is warm and dry. His mother says he went to bed last night without any complaint but woke up this morning with a sore throat and fever. Since he awoke 5 hours ago, the patients fever has risen to 102.3F (39.0C), and the stridor developed. The mother reports the patient has no significant medical history and takes no medications. He has not received all of his vaccinations to date, as the parents are concerned about vaccine side-effects. She is not aware of any recent trauma or potential for foreign body ingestion.

This patients stridor is the result of epiglottitis, a bacterial disease that causes inflammation and edema of the epiglottis and surrounding tissues. As the epiglottis and surrounding structures become inflamed, they can occlude the glottic opening, resulting in an airway obstruction that can vary from partial to complete. Epiglottitis is considered a potentially life-threatening emergency because of the risk of complete airway obstruction. The incidence of epiglottitis in children has significantly decreased in the United States since the H. influenza type b (Hib) vaccine became widely available in the late 1980s, and has declined by more than 99% since the prevaccine era. The CDC reports that since the advent of widespread vaccination, the majority of children (68%) 6 months and older who contract Hib infections are either incompletely vaccinated or have unknown vaccination statuses. The fact that this patient has not received his normal vaccinations increases his risk for Hib infection and epiglottitis. It is worth noting, however, that epiglottitis can still occur in children who have been properly vaccinated and even in those who have received a booster dose of the vaccine. In addition to H. influenza, infection with other bacteria such as group A beta-hemolytic Streptococcus, S. aureus and Streptococcus pneumoniae can result in epiglottitis. The classic presentation of epiglottitis is a patient with acute onset of high fever, sore throat and drooling. The acute onset of high fever tends to be characteristic for bacterial infection, in contrast to the slowly progressing lower fever associated with viral infection. Early in the development of epiglottitis, the patient will experience sore throat, pain with swallowing (odynophagia), inability to swallow (dysphagia) and a change in voice (for example, muffled voice) or cry as the supraglottic structures become inflamed. As the airway diameter decreases due to inflammation, stridor may develop as obstruction worsens. In a worst-case scenario, total airway obstruction can occur. An older patient (child or adult) is less likely to exhibit signs of developing airway obstruction, as the diameter of their airway is relatively larger than a young childs, and significant inflammation and swelling are necessary to produce symptoms.3 Drooling is a cardinal sign and results from a reluctance to swallow due to a severely inflamed and sore throat. As the infection becomes more severe and obstruction worsens, the patient may appear toxic or anxious and assume a tripod or sniffing position to maintain their airway. In addition, signs of severe airway obstruction such as tachypnea, retractions and cyanosis may be present.This patient presented with many signs and symptoms consistent with epiglottitis, including the acute onset of fever, sore throat, odynophagia and inspiratory stridor. The acuity of the illness and the fever suggest an infectious etiology. He also has not been vaccinated, putting him at high risk for Hib infection. This patient appears rather stable at this time, as he does not appear toxic, is not tachypneic or hypoxic, and is managing his secretions well. He is, however, placing himself in the sniffing position. This, with the presence of stridor, indicates he is experiencing some degree of airway obstruction. While his condition appears stable now, it could deteriorate rapidly. Management of epiglottitis, and of this patient, centers on maintaining adequate ventilation and oxygenation. In cases of minimal airway compromise, allow the patient to remain in the most comfortable and relaxed position and manner possible. Typically this means allowing the patient to sit upright and assume a sniffing or tripod position. Do not agitate the patient unnecessarily, and do not insert any objects into the mouth to aid in visualization of the throat. In addition, avoid palpation or any other manipulation of the throat if the patient is experiencing pain. If hypoxia is present, administer humidified oxygen via an appropriate delivery device. No clear recommendations exist for cases of severe airway obstruction secondary to epiglottitis. That being said, there are some basic guidelines that are consistent in emergency medicine. If the obstruction is severe and signs of respiratory failure are present, perform ventilations with a BVM. If complete airway obstruction is imminent, endotracheal intubation (ETI) may be attempted by an experienced provider with a 1 size smaller ETT in anticipation of the swelling within the patients airway. Avoid all non-visualized airways in patients with suspected epiglottitis. Because non-visualized airways such as the LMA and King LT actually sit in the hypopharynx, they are more likely to cause further irritation and inflammation than they are to secure the airway. ETI attempts will be complicated by swollen, distorted anatomy, and any trauma to the airway during ETI could result in additional swelling and bleeding, further complicating the procedure. Typically, in cases of complete airway obstruction where ETI is unsuccessful, surgical cricothyrotomy is indicated. However, this procedure is contraindicated in infants and children due to the size of the cricothyroid membrane. Because of this, needle cricothyrotomy with transtracheal jet ventilation (TTJV) is the preferred approach.

27Airway Infections

EpiglottitisCroupLudwigs anginaBronchiolitisInfluenzaPneumonia

Croup (laryngotracheobronchitis) is another cause of stridor in the pediatric patient, and is usually the result of a viral infection that results in swelling of the laryngeal-tracheal tissues.It is most often the result of parainfluenza virus and occurs most often in children 6 months to 6 years. The typical progression of croup begins with 12 days of nasal congestion, rhinorrhea and low-grade fever prior to the onset of a harsh, seal-like barking cough, hoarse voice and stridor. Symptoms will typically last 37 days, with the most severe manifesting on days 34.5. Severe croup is characterized by worsening stridor, respiratory distress and retractions.The treatment of croup is usually supportive and consists of placing the patient in a position of comfort and administering humidified oxygen. Patients with severe croup may benefit from administration of nebulized racemic epinephrine, which acts on alpha-adrenergic receptors in the subglottic tissue. The resultant vasoconstriction reverses the swelling of the subglottic tissue and airway obstruction. Ludwig's angina is a serious, potentially life-threatening cellulitis, or connective tissue infection, of the floor of the mouth, usually occurring in adults with concomitant dental infections and if left untreated, may obstruct the airways, necessitating tracheotomy.Bronchiolitis is inflammation of the bronchioles. It usually occurs in children less than two years of age. It presents with coughing, wheezing and shortness of breath which can cause some children difficulty in feeding. This inflammation is usually caused by respiratory syncytial virus (RSV) and is much more common in the winter months.Influenza is a viral infection that attacks the respiratory system. Lower-respiratory symptoms include cough and breathing problems. Upper-respiratory symptoms include sore throat, runny nose and congestion. Experimental models of influenza infection reveal that the virus induces death in the cells lining the respiratory tract. These dead cells are shed, enabling the virus to infect progressive cell layers. Influenza and its complications can be deadly.Pneumonia is a lung infection caused by bacteria, a virus or fungi, that inflames the alveoli of the lungs. The alveoli may fill with fluid or pus, causing cough with phlegm, fever, chills and difficulty breathing. Pneumonia and influenza together are ranked as the eighth leading cause of death in the United States

28Case StudyA 38-year-old woman presented to the ED after visiting a relative in the hospital. She gave a 5-year history of recurrent conjunctival edema and rhinitis when blowing up balloons for her children's birthday parties. In the year prior to visit, three successive visits to her dentist triggered marked angioedema of her face on the side opposite to that requiring dental treatment. The swellings took 48 hours to subside.

On the day of ED visit, she visited a critically ill relative in hospital. The patient was on reverse barrier precautions and visitors were required to wear gown and gloves. About 20 min after putting on the gloves her face and eyes became swollen, she felt wheezy and developed a pounding heart beat and light-headedness. Her tongue started to swell.

In the Emergency Department where she was given intramuscular epinephrine (adrenaline) and intravenous hydrocortisone. She recovered rapidly but was kept under observation overnight.

Skin-prick testing to a crude latex extract produced a very strong reaction and her antigen-specific IgE antibody level to latex was significantly elevated. The patient was advised to avoid contact with all materials containing latex, and warned that she could react to certain foods (banana, avocado, kiwi fruit, passion fruit, plums, strawberry and tomatos). The diagnosis has important implications for any further dental, surgical or anaesthetic procedures. It was suggested that she wear a Medic Alert bracelet, in case she required future emergency surgery, and carry a self-injectable form of epinephrine.

29Anaphylaxis

Characterized by respiratory distress (SOB, wheezes &/or stridor, hoarseness, pain with swallowing, cough); tachycardia or bradycardia; hives; swelling of tongue, lips, &/or mouth; and hypotension.Usually results from body response to allergen (medications or additive, contact with natural rubber latex, contact with a solution, environmental, stings or bites).Airway obstruction due to angiodema is major concern!Follow Allergic reaction protocol.Assess for signs and symptoms of allergic reactionAnticipate and prepare for supportive measuresCode cart with appropriate airway management equipment, O2 tank, and medicationsAllergic reaction kitAqueous Epinephrine 1:1000Benadryl H2 antagonist (Famotidine)MethylpredisoneIf allergic reaction is suspected STOP infusion immediately and place patient in trendelenburg position.Call provider immediately and call code blue or rapid response team as appropriate. Give 1st dose Epinephrine 1:1000 0.3 ml IM (infants and children: 0.01 mg/kg; auto injector is 0.15 mg), may repeat every 10-15 minutes to control symptoms or BPMonitor ABC and mentation: Place O2 to maintain adequate saturation. For bronchospasm resistant to epinephrine Albuterol MDI 2 puffs or Nebulized albuterol 2.5-5mg in 3 ml over 5-15 minutes repeat as necessary.

30Case StudyA 15 year old known asthmatic was admitted to the Emergency room after a week of progressive difficulty breathing. Her mother states that she had been sick with and upper respiratory infection and had been using her albuterol inhaler almost hourly until she ran out the day prior. On arrival she is alert, speaking in clipped sentences; sitting upright and appears very anxious. BP 150/90, HR 122, RR 32, O2 saturation 90% on room air.

Over the course of her treatment in the ER she developed progressive hypoxia that was refractory to standard treatment requiring intubation. She was then transferred to the ICU and placed on continuous bronchodilator therapy through the ventilator. After two hours of continuous bronchodilator therapy there was dramatic improvement in her breath sounds. She continued to improve over the next 24 hours, and was extubated the next day.Status Asthmaticus

Severe asthma attack that doesn't respond to usual use of inhaled bronchodilators and is associated with symptoms of potential respiratory failure.Signs & symptoms:Persistent SOBThe inability to speak in full sentences Breathlessness at restChest tightnessCyanosisAgitation, confusion, or an inability to concentrateHunched shoulders and accessory muscle useTripod positioningBeta-agonists and corticosteroids are mainstays in the treatment of status asthmaticus.Oxygen therapy is essential, with hypoxia being the leading cause of death in children with asthma. Indications for intubation & mechanical ventilation: Apnea or respiratory arrestDiminishing LOCImpending respiratory failure marked by significantly rising PCO2 with fatigue & decreased air movementSignificant hypoxemia that is unresponsive to supplemental oxygen Asthma triggers: Airborne allergens, such as pollen, animal dander, mold, cockroaches and dust mitesRespiratory infections, such as the common coldPhysical activity (exercise-induced asthma)Cold airAir pollutants and irritants, such as smokeCertain medications, including beta blockers, aspirin, ibuprofen (Advil, Motrin IB, others) and naproxen (Aleve)Strong emotions and stressSulfites and preservatives added to some types of foods and beverages, including shrimp, dried fruit, processed potatoes, beer and wineGastroesophageal reflux disease (GERD), a condition in which stomach acids back up into your throatMenstrual cycle in some womenTreatmentThe first line of therapy is bronchodilator treatment with a beta2-agonist, typically albuterol. Handheld nebulizer treatments may be administered either continuously (10-15 mg/h) or by frequent timing (eg, q5-20min), depending on the severity of the bronchospasm.The dose of albuterol for intermittent dosing is 0.3-0.5 mL of a 0.5% formulation mixed with 2.5 mL of normal saline. Many of these preparations are available in a premixed form with a concentration of 0.083%.Studies have also demonstrated an excellent response to the well-supervised use of albuterol via an MDI with a chamber. The dose is 4 puffs, repeated at 15- to 30-minute intervals as needed. Most patients respond within 1 hour of treatment.Anticholinergic agents are believed to have an inhibitory effect on parasympathetic nervous system. They may also decrease mucus production and improve mucociliary clearance. Ipratropium bromide (Atrovent), is the recommended agent of choice. It is administered every 4-6 hours, and can be synergistic with albuterol or other beta2-agonists when treating severe acute asthma exacerbations. Glucocorticosteroids may be the most important treatment for status asthmaticus. These agents can decrease mucus production, improve oxygenation, reduce beta-agonist or theophylline requirements. Corticosteroids may be administered intravenously or orally. Although most practitioners administer corticosteroids intravenously during status asthmaticus, some studies indicate that early administration of oral corticosteroids may be just as effective. Corticosteroid action usually requires at least 4-6 hours to occur following corticosteroid administration because protein synthesis is required before the initiation of a corticosteroids anti-inflammatory effects. Because of this, patients with status asthmaticus must depend on other supportive measures (eg, beta2-agonists, oxygen, adequate ventilation) in their initial treatment while awaiting the action of corticosteroids. the effects of theophylline that are important in managing asthma are bronchodilatation, increased diaphragmatic function, and central stimulation of breathing. Usually, theophylline is given parenterally, but it can also be given orally, depending on the severity of the asthma attack and the patient's ability to take medications. This class of drugs can induce tachycardia and decrease the seizure threshold (especially in children); therefore, therapeutic monitoring is mandatory. Intravenous magnesium sulfate infusion has been advocated in the past for the treatment of acute asthma. Magnesium can relax smooth muscle and hence may cause bronchodilation by competing with calcium at calcium-mediated smooth muscle binding sites. Usually 1 gram or a maximum of 2.5 grams during the initiation of therapy may be considered.Heliox (ie, 30/70 mixture) has been studied, but this treatment should only be considered in patients who are able to take deep breaths, because the treatment is dependent on inspiratory flow. The administration of a heliox reduces turbulent airflow across narrowed airways, which can help to reduce the work of breathing. This, in turn, can result in improved gas exchange and improve pH and clinical symptoms. Heliox loses most of its clinical utility when the FiO2 is greater than 40%, reducing the percentage of helium to less than 60%. Therefore, the limitation to the use of heliox is the amount of supplemental oxygen the patient requires to maintain adequate oxygen saturation. The decision to intubate a patient with asthma should be made with extreme caution. Positive pressure ventilation in a patient with asthma is complicated by the severe airway obstruction and air trapping, which results in hyperinflated lungs that may resist further inflation and places the patient at high risk of barotrauma. Therefore, mechanical ventilation should be undertaken only in the face of continued deterioration despite maximal bronchodilatory therapy. If all other support modalities fail and extracorporeal membrane oxygenation (ECMO) may be required32Case StudyA 64-year-old female status post aortic valve replacement for severe aortic stenosis late on POD 2 suddenly experienced severe shortness of breath and began to cough up frothy pink sputum. The patient remained alert but became mildly confused, on auscultation exhibited end-inspiratory crackles throughout her lung bases, a pulse of 123 beats/min, a blood pressure of 121/73 mm Hg, and a respiratory rate of 28-32.

Within 25 minutes of symptoms, she was intubated for ventilation, vigorous diuresis occurred and the patient's initially normal blood pressure plummeted to