BY STEVE KANARIAN
EMS providers routinely respond to emergency calls for difficulty breathing. Determining the cause of respiratory distress can challenge even the most seasoned firefighters. Respiratory distress calls often require quickly sorting through multiple medical problems to select the most urgent and targeting emergency treatment to ensure good patient outcomes. Pulmonary edema patients may have overlapping symptoms of pneumonia, chronic obstructive pulmonary disease (COPD), or asthma. Reviewing symptoms and performing a physical assessment with knowledge and precision are needed to accurately differentiate pulmonary edema from pneumonia and to consider the potential overlaps of other medical problems.
| Figure 1. Capillary Leaking into Alveoli from Increased Osmotic Pressure |
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This article will sharpen your ability to diagnose pulmonary edema. As a new paramedic, I was fortunate to have worked with very experienced senior medics. My assessment and treatment were based on paramedic training and tailored by these medics’ experience. With the sage advice of our actively involved prehospital medical control physicians, I learned to put the pieces of the puzzle together and complete the diagnosis when faced with a patient with multiple respiratory diseases. EMTs who want to expand their knowledge about assessment of the cardio-respiratory patient in preparation for paramedic training will especially benefit from this article. Let’s look at a prehospital case involving the differential diagnosis of pulmonary edema and the paramedic approach to making an accurate differential diagnosis between pulmonary edema and other respiratory diseases.
CASE STUDY
At 0404 hours, your advanced life support engine is dispatched to a private home for a 60-year-old female complaining of difficulty breathing. You are the lead paramedic. Entering the bedroom, you observe the patient sitting on a chair in the tripod position. She is mildly obese, pale, and diaphoretic and has a faint cyanotic color to her face. She reaches out to you, “Help me, I … ca … n’t … breathe.” Your crew quickly places the patient on 100-percent oxygen by nonrebreather mask. They obtain vital signs and an electrocardiogram (ECG). Placing your hand on the patient’s shoulder, you reassure her, “We are going to help you breathe better. Relax and concentrate on your breathing.” When asked about the patient’s past medical history (PMH), her husband explains, “She has heart failure, diabetes, and high blood pressure.”
The history of present illness (HPI) you have pieced together from the husband is that the patient awoke out of her sleep this morning with shortness of breath and has experienced increased shortness of breath when walking from the first floor to the second floor of her home over the past few days. She has had a “cold,” and her husband thinks she may now have pneumonia.
The family brings you the patient’s medications. Your partner reads them off, “Lasix, 80 milligrams, twice daily; Digoxin, 0.125 milligrams, once daily; regular insulin, 30 units, twice daily; levofloxacin (Levaquin); and an albuterol inhaler.” The daughter interjects, “She’s had water on the lungs twice this year and a recent respiratory infection. Oh, she also has borderline kidney failure from diabetes, and we have not been able to get her to quit smoking.”
Your partner tells you, “BP is 170/104, pulse 118 and irregular, resps 28, and pulse ox 89 percent. She is in atrial fibrillation with no ectopy. The 12-lead ECG shows no ST elevation or other abnormalities. Which way are we going with treatment?” The decision is in your hands on how to care for this acutely ill patient. What is your impression so far? What treatment are you considering? Most importantly, what additional questions and parts of the history and physical would you like to develop further?
Accurately diagnosing the emergent problem in this patient is crucial to delivering the right treatment. Failing to treat acute pulmonary edema may further decrease oxygen saturation leading to hypoxia that may require intubation, a longer intensive care unit admission, and possibly a cardiac arrest. Administering diuretics to a patient with pneumonia will worsen dehydration and potentially cause arrhythmias from electrolyte imbalances. Contrarily, treating a cardiogenic shock patient with medications for pulmonary edema will cause hypotension and worsen the patient’s outcome. A clear diagnosis may not be possible in our discussion case using the preliminary information collected to this point. Let’s review the basics of cardiorespiratory assessment and the keys to making the differential diagnosis of pulmonary edema.
THE DIFFERENTIAL DIAGNOSIS
Paramedics evaluating a cardiorespiratory patient should use a systematic and complete HPI, a PMH, and a focused physical assessment. Only with all the pertinent elements of each part of the prehospital assessment can a medic accurately determine the presenting problem and best course of treatment. Our patient in the above scenario has several overlapping disease processes, which require us to differentiate between the diseases and determine treatment priorities. The more complex the diagnosis, the more precise the assessment and history have to be.
When responding to a call for shortness of breath, our diagnosis starts before we touch the patient. When reviewing dispatch data, think about the time of day, the location, and the age of the patient. A 60-year-old with shortness of breath in the early morning may be a clue that the patient is in pulmonary edema. A call for a shortness of breath and fever in a nursing home may suggest a diagnosis of sepsis or pneumonia. On arrival, we obtain information from bystanders, first responders, and the family and form an initial impression when we see the patient. During our initial impression, we consider the position of the patient, the degree of difficulty in breathing, accessory muscle use, and the patient’s ability to speak in complete sentences. For example, responding to a home during the summer and finding a patient in the fetal position under a blanket may be an indication that he or she has a fever and not necessarily asthma or acute pulmonary edema (APE). Multiple family members with histories of recent respiratory illness or distant travel may clue you in to problems such as carbon monoxide poisoning, the H1N1 virus, or severe acute respiratory syndrome (SARS)-like illnesses.
OBTAINING THE PATIENT HISTORY AND PHYSICAL EXAM
Obtaining an HPI allows us to collect information on which to base our diagnosis. The acronym OPQRST (onset, provocation/palliation, quality, radiation, severity, and time) is useful for exploring a chief complaint of pain. Considering pertinent positives and negatives will help you determine the cause of the patient’s respiratory distress. For example, a rapid onset of shortness of breath may point to APE or asthma. A history of recent surgery or of being confined to bed may be an indication of pneumonia or pulmonary embolism. Providers should ask if the patient has a cough and, if the cough is productive, the color and consistency of phlegm. If they normally have a productive cough, ask if the cough or phlegm has changed. We should also ascertain whether a patient has orthopnea (trouble breathing when lying flat), if she has been sleeping flat or has been using pillows to elevate her head, or if she has complained of dyspnea on exertion.
The patient’s past medical history may give clues to the present condition, because patients often experience the same problems repetitively. Use the SAMPLE acronym to develop a complete HPI (signs and symptoms, allergies, medications, past history, last meal, and events leading up to the 911 call). A patient who was admitted for “water on the lungs” probably had a heart failure exacerbation or APE. A patient with renal failure may have missed a dialysis appointment or consumed more fluids than usual and be at risk for pulmonary edema. Diabetes and high blood pressure are contributing factors to both kidney and heart failure. Obtaining information about frequency of dialysis, medications, and compliance are very important. They are also a teaching opportunity when time permits, as the majority of heart failure patients who require hospitalization for APE are noncompliant with their prescribed medication and dietary regimen.
Patients with bronchitis or emphysema will have a history of shortness of breath coinciding with a change in weather or recent infection. In determining the cause of a respiratory illness, the color of phlegm can be very helpful. A cough productive of green or yellow phlegm indicates infection, whereas a cough productive of white blood-tinged sputum is classic for pulmonary edema.
PHYSICAL FINDINGS
The most important aspect of focused physical assessment is performing the cardiorespiratory assessment completely each time you assess a patient with shortness of breath or chest pain. Heart failure patients commonly experience increased dyspnea on exertion over time, increased fluid retention, swelling of the ankles, and jugular venous distention (JVD). A complete cardiorespiratory assessment is crucial for determining whether a patient is experiencing right-sided or left-sided heart failure. Nail clubbing, yellowish fingertips, purse-lipped breathing, and increased chest diameter (from years of smoking) are clear indicators that the patient has a history of COPD. A comprehensive textbook on physical examination such as The Mosby Guide to Physical Assessment serves as an excellent resource for in-depth review and improving your knowledge of assessment and history taking.
DIAGNOSTIC TESTS
Monitoring and 12-lead ECG, pulse oximetry, and waveform capnography are all helpful tools for making the correct diagnosis of respiratory problems. A monitoring ECG is an important tool to identify life-threatening rhythms like ventricular tachycardia or supraventricular tachycardia. Rapid treatment of unstable dysrhythmia may reverse pulmonary edema, when effective. A 12-lead ECG may identify blocked coronary arteries in STEMI and can be crucial in aggressively treating and resolving myocardial ischemia and preventing heart failure. Pulse oximetry provides an indication of the percent of hemoglobin saturated with oxygen. Hypoxic patients may appear anxious with high yields of carbon dioxide or be quiet when hypoxic. Pulse oximetry will identify those patients who are in respiratory failure and in need of oxygen and treatment to facilitate respiration. Waveform capnography is essential for monitoring patients with respiratory distress and can be extremely useful for differentiating causes. (See “Capnography: A Tool for Every Patient,” Jim Davis, Fire Engineering, January 2009, p.99.)
PATHOPHYSIOLOGY OF CARDIOGENIC PULMONARY EDEMA
A normally functioning heart circulates blood to the pulmonary circulation via the right ventricle and to the systemic circulation through the left ventricle. Sufficient circulation is needed from the left ventricle to adequately perfuse the brain, kidneys, liver, and other essential organs. When cardiac function is impaired, the pathological effects inhibit the body’s ability to provide oxygen and glucose to cells. Cardiogenic pulmonary edema is caused by the failure of the left ventricle to adequately pump blood to the systemic circulation. Pulmonary edema causes hypertension, shortness of breath, and hypoxia.
As the left ventricle fails, pressure builds and backs up into the left atrium, and then into the pulmonary veins. Increased pressure in the pulmonary circulation from left ventricular failure causes an increased pressure in the pulmonary capillary bed. The pressure in the capillaries is called “osmotic pressure.” Increased osmotic pressure in the capillary bed causes the bronchioles to swell and fluid to diffuse into the alveoli when osmotic pressure reaches the 18-20 mmHg range. As the osmotic pressure in the capillaries begins to leak through the capillary walls, fluid accumulates in the alveoli, causing fine rales (crackles) best heard on inspiration. Rales are short and discontinuous and sound similar to strands of hair being rubbed together. As fluid levels increase, alveoli fill with fluid, rendering them unable to transfer oxygen to the blood. Widespread alveolar filling results in shunting, which effectually implies that large parts of the lung have lost their ability to participate in oxygen and carbon dioxide exchange. Shunting (and elevated fluid levels) increases hypoxia in patients.
Left-sided heart failure causes bilateral rales in the lung bases; as pulmonary congestion increases, the level of rales rises. “Cardiac Asthma” is a colloquial term used to describe the presence of wheezing caused by distention of the bronchial walls prior to the flow of fluid into the alveoli. Wheezing may precede rales and APE. APE may be compared to asthma because of the resultant wheezing secondary to bronchiole swelling. Some providers describe the rapid filling of fluid into the lungs as a “flashover.” An astute paramedic who is well versed in respiratory diseases can detect APE just prior to flashover and prepare for appropriate treatment.
Pulmonary edema fills the alveoli, causing a decrease in oxygen transfer to hemoglobin and hypoxemia. Serous fluid in the alveoli reduces the surface area available for the exchange of oxygen and carbon dioxide with the blood. The lack of oxygen available to essential body tissue and systems has profound effects on the patient. As the lungs fill with fluid, carbon dioxide builds up, and hypoxia ensues because of decreased tidal volume. The patient becomes anxious because of a buildup of carbon dioxide and experiences increased dyspnea and agitation. Pulmonary edema is frequently associated with an adrenergic release, which causes diaphoresis, pallor, and anxiety.
DIAGNOSIS OF PULMONARY EDEMA
The diagnosis of pulmonary edema is based on physical signs, symptoms, and the HPI. Physical findings of APE include rales bilaterally in the lungs, cough productive of white or blood-tinged sputum, an abnormal S3 heart sound, and pedal edema. Percussion of the chest may produce dullness or normal lung resonance. APE patients typically experience pronounced shortness of breath, called “dyspnea paroxysmal nocturnal dyspnea” (PND), which awakens them out of their sleep. Skin color in a patient with cardiogenic pulmonary edema will usually be pale, diaphoretic, and sometimes cyanotic.
Differential diagnosis of APE warrants consideration of other pulmonary diseases. Pneumonia, COPD, and asthma can share similar physical findings with APE at various stages. A discussion of the signs and symptoms of these diseases is essential to properly diagnose APE vs. other pulmonary diseases.
PATHOPHYSIOLOGY OF PNEUMONIA
Pneumonia is the sixth leading cause of death in the United States and results from infection or from aspiration of gastric contents. Pneumonia usually begins with infection in a lung lobe, which causes production of sputum. A buildup of sputum in the alveoli interferes with the absorption of oxygen into the capillaries by decreasing alveolar surface area. The body tries to fight infection by raising body temperature and expectorating phlegm by coughing. The pneumonia patient experiences shortness of breath, coughing, and pleuritic chest pain; the symptoms begin gradually over days or weeks. On physical examination, a pneumonia patient may have flushed, hot skin; dehydration; localized rhonchi; and dullness on percussion of the chest. Rhonchi are deep, prolonged rumbling sounds heard during exhalation. A pneumonia patient may have a productive cough with green or yellow sputum. APE patients experience an acute shortness of breath and a cough with white or blood-tinged sputum. Patients at risk for pneumonia are often bedridden or postsurgical or have sepsis caused by another infection. Pneumonia caused by sepsis can often be tracked to a urinary or respiratory tract or other localized infection.
ASTHMA
Asthma is considered an obstructive lung disease caused by an autoimmune response or environmental irritant. Asthma involves narrowing of the airway, inflammation of the mucous membrane, and retention of carbon dioxide. An asthma patient may or may not have a productive cough. On physical examination, asthma patients may have expiratory wheezing, which may become increasingly more pronounced. An asthma patient may have a normal or hyperresonant chest on percussion. Asthma patients will often have a history of allergies or eczema.
COPD
The COPD emphysema and bronchitis differ from APE in the patient’s physical appearance and chief complaint presentation. A bronchitis patient typically has a large barrel chest, cyanotic color, and a history of chronic cough for several years. Deep coughing associated with sputum production dominates a bronchitis patient’s complaint. The color of the bronchitic cough can be clear, yellow, or green. Chest size is a characteristic of COPD. Bronchitis patients have a large barrel chest caused by overexpansion. Emphysema patients have a thin wasted appearance because they use all of their energy to breathe. Patients with COPD have pursed lips and nail bed clubbing, a rounded-out appearance of the nail beds of the fingers. A 10-pack-year smoking history is suggestive of COPD (i.e., smoking one pack of cigarettes daily for 10 years, or two packs daily for five years). The COPD patient usually will have hyper-resonance on chest wall percussion because of carbon dioxide retention, which overinflates the alveoli and bronchi. On auscultation, the COPD patient may have bronchial wheezing and/or rhonchi.
FINE POINTS OF MAKING THE DISTINCTION
Often, an obvious or clear diagnosis is not possible with information collected in the field. A paramedic must incorporate the clinical information and physical findings presented to identify the disease process posing the most immediate life threat to the patient.
Paramedics can use the technique of trending to determine the patient’s diagnosis when a clear diagnosis is not immediately obvious. When faced with a critically ill patient with signs of overlapping respiratory diseases, paramedics should perform assessment, provide oxygen, establish IV access, and obtain an ECG. When in doubt, withhold medications until the diagnosis is clearer. Assess the patient again before removing him from the building and then again during transport. Over time, the vitals and lung sounds may evolve and help you determine the direction in which a patient’s complaint is developing and monitor changing physical findings to diagnose the most urgent medical problem. Contact medical control if you need clarification of the presenting complaints. Medical control will greatly appreciate your complete physical and thorough history, which will positively reflect on your professionalism.
ANOTHER LOOK AT OUR CASE STUDY
The patient is a 60-year-old woman with severe shortness of breath that awoke her out of her sleep. She is coughing and sitting in the tripod position. Our first impression is that the patient is critical, suffering from severe respiratory distress, indicated by her inability to speak and the O2 saturation of 89 percent. We were advised that she has heart failure, diabetes, high blood pressure, and some degree of renal failure. The patient takes medications consistent with heart failure, respiratory ailments, and possibly pneumonia. Providing care for this patient requires us to accurately determine the cause of her distress. Let’s develop a clearer history and assessment.
HISTORY OF PRESENT ILLNESS
To clarify the HPI, you need to determine the color of the cough sputum, whether she sleeps on pillows, and if she has taken any medications to relieve her symptoms. It is clear that the onset of her shortness of breath is consistent with paroxsysmal nocturnal dyspnea (PND). Past medical history would be clarified by asking if she has COPD or a history of smoking. “Is this like other times you have had trouble breathing from heart failure?” “Have you ever been intubated?” Determine the extent of her renal failure by asking if she gets dialysis and if she is compliant. Assessment should always include level of consciousness, jugular vein distention, lung sounds in six locations in front and back, heart sounds, and looking for pedal edema. We determine she is alert and oriented, has JVD, lungs are two-thirds filled with rales, heart sounds are a positive S3 sound, and she has four cm of pedal edema to the pretibial area. When the patient coughs, the larger airway sounds do not change, and her sputum is white blood-tinged. She denies having a fever or chills and is not warm to the touch. This information, coupled with her HPI, allows you to presumptively diagnose that she has APE.
At this point, you and your partner feel comfortable with a presumptive diagnosis of APE. You start an IV normal saline lock with an 18-gauge catheter in the left forearm. You administer continuous positive airway pressure (CPAP) to help clear the alveoli and improve oxygen absorption in the alveoli and pulmonary capillary bed. You administer sublingual nitroglycerine and begin transport. En route to the hospital, you contact medical control and are advised to give additional nitroglycerine and to monitor the blood pressure. On your arrival at the hospital, the lungs have fine rales in the bases, the patient is dry, and her color is returning. The emergency department physician inquires, “Is this the patient you called about? She looks less critical than you presented her.” You reply, “Yes doc, she is better now.” “Well done,” he compliments.
The care provided for this patient benefitted her outcome, increased her survival, and shortened her hospital stay. The patient was not given morphine because she did not complain of pain and her anxiety was controlled with reassurance. Morphine may relax a patient when given judiciously, but it has the side effect of decreasing the level of consciousness and respiratory drive and leads to intubation and longer hospital stays. Medical directors are moving toward increased use of nitroglycerine and CPAP with less emphasis on morphine. Lasix might have been given, but the patient responded well to CPAP and was not subjected to the risk of electrolyte imbalance. Newer evidence suggests that a significant number of patients with APE are volume depleted rather than volume overloaded. This is casting doubt on the efficacy of diuretics in treatment of acute heart failure episodes. Treatment should always be in accordance with your local protocol and the directions of medical control. The best way to continue to learn about medical problems and cases is to follow up on your patients and discuss the medical treatment with your medical director.
RESPIRATORY DISEASES ON A CONTINUUM OF SEVERITY
Diseases appear in patients on a continuum of severity. For example, a patient may be having an asthma attack and may also be suffering from a respiratory infection. With experience, providers assess and treat patients ranging from a minor asthma attack with a cough to a more severe attack with a silent chest. Diseases can be charted on a continuum from minor severity on the left to severe shortness of breath and finally to respiratory arrest on the extreme right side. Once you have seen the range of severity, you can tailor the appropriate treatment to what is best for each patient. Prioritizing care of multiple medical problems requires prioritizing which problems most affect a patient’s survival. Medical problems such as COPD, heart failure, and asthma often affect the same patient at the same time. Deciding which elements to treat is the effective way to manage the patient.
Discussion of the elements of a thorough HPI and PMH coupled with the pathological causes of respiratory disease gave us a basis on which to make a presumptive diagnosis of cardiogenic pulmonary edema. A large part of professionalism as a paramedic is accomplished by continually striving to learn, exhibiting empathy for patients, and providing the most appropriate care and transport decisions. Your professionalism will be validated by applying the principles in this article to all your cardiac and respiratory patients.
References
1. Des Jardin, Terry. Clinical Manifestations and Assessment of Respiratory Disease. (St. Louis, Mo.: Mosby Inc., 2002).
2. Pollak, Andres N, MD. Nancy Caroline’s Emergency Care in the Streets. (Sudbury, Mass.: Jones and Bartlett, 2008).
3. Wilkns, R, J Stoller, R Kacmarek. Egan’s Fundamentals of Respiratory Care.(St. Louis, Mo., Mosby Inc., 2009).
4. Seidel, H., J Ball, J Dains, G Benedict. Mosby’s Guide to Physical Examination. (6th ed). Mosby, 2006.
5. Zipes, Libby, Bono Braunwald. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. ( 7th edition. (Philadelphia, Penn. Elsevier Saunders, 2005).
STEVEN KANARIAN, MPH, is the instructor coordinator for the LaGuardia Community College (City University of New York) Paramedic Program in Queens, New York. He is a retired lieutenant with the Fire Department of New York, EMS Command.
