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Medical Emergencies . Anuradha Perera (B.Sc.N)special Respiratory failure Definitions • acute respiratory failure occurs when: – pulmonary system is no longer able to meet the metabolic demands of the body • hypoxaemic respiratory failure: – PaO2 50 mm Hg when breathing room air • hypercapnic respiratory failure: – PaCO2 50 mm Hg. Oxygen in • Depends on – – – – PAO2 Diffusing capacity Perfusion Ventilation-perfusion matching Oxygen Carbon dioxide Water vapour Nitrogen Alveolarpressure PAO2 PACO2 PAH2O PAN2 Pathophysiology Perfusion without ventilation (Shunting) • Intra-cardiac – Any cause of right to left shunt • eg Fallot’s, Eisenmenger • Intra-pulmonary – – – – – Pneumonia Pulmonary oedema Atelectasis Collapse Pulmonary haemorrhage or contusion Perfusion without ventilation (shunting) Intra-pulmonary • Small airways occluded ( e.g asthma, chronic bronchitis) • Alveoli are filled with fluid ( e.g pulm edema, pneumonia) • Alveolar collapse ( e.g atelectasis) Brainstem Airway Lung Spinal cord Nerve root Nerve Pleura Chest wall Neuromuscular junction Respiratory muscle Sites at which disease may cause ventilatory disturbance Respiratory Failure Symptoms CNS: Headache Visual Disturbances Anxiety Confusion Memory Loss Weakness Decreased Functional Performance Respiratory Failure Symptoms Pulmonary: Cough Chest pains Sputum production Stridor Dyspnea Respiratory Failure Symptoms Cardiac: Orthopnea Peripheral edema Chest pain Other: Fever, Abdominal pain, Anemia, Bleeding Clinical • Respiratory compensation • Sympathetic stimulation • Tissue hypoxia • Haemoglobin desaturation Clinical • Respiratory compensation – – – – Tachypnoea RR > 35 Breath /min Accessory muscles Recesssion Nasal flaring • Sympathetic stimulation • Tissue hypoxia • Haemoglobin desaturation Clinical • Respiratory compensation • Sympathetic stimulation – HR – BP – sweating • Tissue hypoxia • Haemoglobin desaturation Clinical • Respiratory compensation • Sympathetic stimulation • Tissue hypoxia – Altered mental state – HR and BP (late) • Haemoglobin desaturation Clinical Altered mental state ⇓PaO2 +⇑PaCO2 ⇨ acidosis ⇨ dilatation of cerebral resistance vesseles ⇨ ⇑ICP Disorientation Headache coma personality changes Clinical • Respiratory compensation • Sympathetic stimulation • Tissue hypoxia • Haemoglobin desaturation – cyanosis Respiratory Failure Laboratory Testing Arterial blood gas PaO2 PaCO2 PH Chest imaging Chest x-ray CT sacn Ultrasound Ventilation–perfusion scan Respiratory Failure Laboratory Testing Respiratory mechanics Spirometry (FVC, FEV1, Peak flow) Respiratory muscle pressures MIP ( maximum inspiratory pressure) MEP ( maximum expiratory pressure) Respiratory Failure Laboratory Testing Other tests Hemoglobin Electrolytes, blood urea nitrogen, creatinine Creatinine phosphokinase, aldolase EKG, echocardiogram Electromyography (EMG) Nerve conduction study True or False •Diffusion abnormality is considered the most common cause of hypoxia. True or False •Dead space ventilation decreases when blood flow is reduced True or False •Shunt occurs when areas of lung are perfused but not ventilated True or False •In myasthenia gravis mechanism of hypoxia may be due to alveoli being perfused but not ventilated True or False •Arterial hypoxemia may be caused by alveolar hypoventilation alone True or False • The distinction between ventilation/perfusion mismatch and intrapulmonary shunting can be made by measuring the response to the administration of 100% oxygen True or False • There is a good relationship between dyspnea and arterial hypoxemia but a poor relationship between dyspnea and arterial carbon dioxide retention Which of the following statements regarding the physical examination for patients with acute respiratory failure are true or false? • Central nervous examination is important • Breath sounds are commonly diminished • Supraclavicular and intercostal space muscle retractions do not correlate with increased work of breathing QUESTIONS ? ? ? ? Pulse oximetry Hb saturation (%) 90 8 PaO2 (kPa) Cardiac failure Heart Attack • Acute myocardial infarction (AMI) • Pain signals death of cells. • Opening the coronary artery within the first hour can prevent damage. • Immediate Signs and Symptoms • Sudden onset of weakness, nausea, sweating without obvious cause • Chest pain/discomfort – Often crushing or squeezing – Does not change with each breath • Pain in lower jaw, arms, back, abdomen, or neck • Sudden arrhythmia with syncope • Shortness of breath or dyspnea • Pulmonary edema Pain of Heart Attack • May or may not be caused by exertion • Does not resolve in a few minutes • Can last from 30 minutes to several hours • May not be relieved by rest or nitroglycerin Sudden Death • 40% of AMI patients do not reach the hospital. • Heart may be twitching. Arrhythmias Bradycardia Ventricular Tachycardia Cardiogenic Shock • Heart lacks power to force blood through the circulatory system. • Onset may be immediate or not apparent for 24 hours after AMI. Congestive Heart Failure • CHF occurs when ventricles are damaged. • Heart tries to compensate. • Increased heart rate • Enlarged left ventricle • Fluid backs up into lungs or body as heart fails to pump. • You obtain a brief history while taking the patient’s blood pressure. • Your partner retrieves the nitroglycerin and obtains permission from medical control. • Your partner administers the nitroglycerin. • What else can you do at this time? You are the Provider (continued) Focused History and Physical Exam • Medications are important! • Medications often prescribed for CHF: – Furosemide – Digoxin – Amiodarone Focused Physical Exam • Cardiac and respiratory systems • Look for skin changes. • Lung sounds • Baseline vital signs – BOTH systolic and diastolic BP readings Communication Relay history, vital signs, changes, medications, and treatments. Aspirin • Administer according to local protocol. • Prevents clots from becoming bigger • Normal dosage is from 162 to 324 mg. Nitroglycerin • Forms – Pill, spray, skin patch • Effects – Relaxes blood vessel walls – Dilates coronary arteries – Reduces workload of heart Nitroglycerin Contraindications • Systolic blood pressure of less than 100 mm Hg • Head injury • Maximum dose taken in past hour Nitroglycerin Potency • Nitroglycerin loses potency over time. – Especially if exposed to light • When nitroglycerin tablets lose potency: – May not feel the fizzing sensation – May not experience the burning sensation and headache • Fizzing only occurs with a potent Assisting With Nitroglycerin • Obtain order from medical direction. • Take patient’s blood pressure. (1 of 4) Assisting With Nitroglycerin (2 of 4) • Check that you have right medication, patient, and delivery route. • Check expiration date. • Find out last dose taken and effects. • Be prepared to lay the patient down. Assisting With Nitroglycerin 4) (3 of • Administer tablet or spray under tongue. • Have patient keep mouth closed until tablet dissolves or is absorbed. Assisting With Nitroglycerin (4 of 4) • Recheck blood pressure. • Record each activity and time of application. • Reevaluate and note response. • May repeat dose in 3 to 5 minutes. Ongoing Assessment • Repeat initial assessment. • Reassess vital signs every 5 minutes. • Monitor closely. • If cardiac arrest occurs, begin defibrillation or CPR immediately. • Record interventions, instructions from medical control, patient’s response. Heart Surgeries and Pacemakers • Coronary artery bypass graft (CABG) • Angioplasty • Cardiac pacemaker Automatic Implantable Cardiac Defibrillators (1 of 2) • Maintains a regular heart rhythm and rate • Do not place AED patches over pacemaker. Automatic Implantable Cardiac Defibrillators (2 of 2) • Monitor heart rhythm and deliver shocks as needed. • Low electricity will not affect rescuers. Cardiac Arrest • The complete cessation of cardiac activity, either electrical, mechanical, or both. Automated External Defibrillator (AED) • AEDs come in various models. • Some operator interaction required. • A specialized computer recognizes heart rhythms that require defibrillation. Potential AED Problems • Battery is dead. • Patient is moving. • Patient is responsive and has a rapid pulse. AED Advantages • ALS providers do not need to be on scene. • Remote, adhesive defibrillator pads are used. • Efficient transmission of electricity Non-Shockable Rhythms • Asystole • Pulseless electrical activity Rationale for Early Defibrillation • Early defibrillation is the third link in the chain of survival. • A patient in ventricular fibrillation needs to be defibrillated within 2 minutes. AED Maintenance • Read operator’s manual. • Check AED and battery at beginning of each shift. • Get a checklist from the manufacturer. • Report any failures to the manufacturer and the FDA. Medical Direction • Should approve protocols • Should review AED usage • Should review speed of defibrillation • Should provide review of skills every 3 to 6 months Preparation • Make sure the electricity injures no one. • Do not defibrillate a patient lying in pooled water. • Dry a soaking wet patient’s chest first. • Do not defibrillate a patient who is touching metal. • Remove nitroglycerin patches. Using an AED (1 of 8) • Assess responsiveness. • Stop CPR if in progress. • Check breathing and pulse. • If patient is unresponsive and not breathing adequately, give Using an AED (2 of 8) • If there is a delay in obtaining an AED, have your partner start or resume CPR. • If an AED is close at hand, prepare the AED pads. Using an AED (3 of 8) • Remove clothing from the patient’s chest area. Apply pads to the chest. • Stop CPR. • State aloud, “Clear the patient.” Using an AED (4 of 8) • Push the analyze button, if there is one. • Wait for the computer. • If shock is not needed, start CPR. • If shock is advised, make sure that no one Using an AED (5 of 8) • After the shock is delivered, begin 5 cycles of CPR, beginning with chest compressions. • After 5 cycles, reanalyze patient’s rhythm. • If the machine advises a shock, clear the patient and push shock button. • If no shock advised, check for pulse. Using an AED (6 of 8) • If the patient has a pulse, check breathing. • If the patient is breathing adequately, provide oxygen via nonrebreathing mask and Using an AED (7 of 8) • If the patient is not breathing adequately, use necessary airway adjuncts and proper positioning to open airway. • Provide artificial ventilations with Using an AED (8 of 8) • If the patient has no pulse, perform 2 minutes of CPR. • Gather additional information on the arrest event. • After 2 minutes of CPR, make sure no one is touching the patient. • Push the analyze button again (as applicable). • If necessary, repeat alternating CPR/Analyze/Shock until ALS arrives. • Transport and check with medical After AED Shocks • Check pulse. • No pulse, no shock advised • No pulse, shock advised • If a patient is breathing independently: – Administer oxygen. – Check pulse. • If a patient has a pulse but breathing is inadequate, assist ventilations. Transport Considerations • Transport: – When patient regains pulse – After delivering six to nine shocks – After receiving three consecutive “no shock advised” messages • Keep AED attached. • Check pulse frequently. • Stop ambulance to use an AED. Cardiac Arrest During Transport (1 of 2) • Check unconscious patient’s pulse every 30 seconds. • If pulse is not present: – – – – – Stop the vehicle. Perform CPR until AED is available. Analyze rhythm. Deliver shock(s). Continue resuscitation according to local protocol. Cardiac Arrest During Transport (2 of 2) • If patient becomes unconscious during transport: – – – – – – Check pulse. Stop the vehicle. Perform CPR until AED is available. Analyze rhythm. Deliver up to three shocks. Continue resuscitation according to local protocol.