General Management of Medical Conditions in the Wilderness



General Management of Medical Conditions in the Wilderness


Leah Jacoby Groves

Tracy A. Cushing



INTRODUCTION

As noted in Chapter 1, wilderness medicine is defined as medical care delivered in those areas where fixed or transient geographic challenges reduce availability of, or alter requirements for, medical or patient movement resources.1,2,3,4 Many medical emergencies that occur in a wilderness setting are directly related to the environment, such as altitude illness, heat or cold exposure, traumatic injuries, and animal bites. However, everyday medical conditions, similar to those seen in a front country setting, can and do occur.



Scope of Discussion

This chapter will cover a broad range of medical conditions, from asthma to abdominal pain to stroke to diabetes and beyond. A good wilderness emergency medical services (WEMS) practitioner should be able to identify and understand basic medical conditions, and to prevent those conditions from becoming acute problems in a wilderness environment when possible. Some conditions, however, are unavoidable, and we will discuss different treatment options in the wilderness setting, paying attention to what types of equipment might be at your disposal (as well as what types of equipment you normally use to help diagnose and treat these conditions that might be missing).

By the end of this chapter, you should be able to recognize basic medical conditions in a wilderness environment, know how to treat these conditions, know what types of equipment to consider having access to as a wilderness medicine provider, and have an understanding of how to prevent certain medical conditions from becoming more severe or life-threatening.


EPIDEMIOLOGY

Wilderness recreation has become an increasingly popular activity over the past 40 years. According to the National Park Service (NPS), 307 million recreational visits occurred in 2015 nationwide, up from 198 million recreational visits in 1979.5 In addition to increases in outdoor recreation, our population is living longer and becoming more active later in life.6 Many older individuals have comorbid health conditions with the potential to cause medical emergencies. An analysis of emergency medical services (EMS) activations in Shenandoah National Park over a 5-year period showed that almost half of the calls were due to a medical illness, and the majority of those patients had comorbid health conditions.7 Likewise, a review of search and rescue incidents over a 10-year period in Yosemite National Park and a 4-year period in Utah National Parks showed at least one-third of these calls were due to nontraumatic medical causes.8,9
As more people continue to engage in wilderness activities, there will likely be an increase in the number of EMS system activations due to medical reasons.


CLINICAL MANAGEMENT


Cardiac/Chest Pain

Heart disease is the leading cause of death among both men and women in the United States.10 Common risk factors for the development of heart disease include high blood pressure, high cholesterol, diabetes, obesity, poor diet, and sedentary lifestyle. While cardiac conditions such as coronary artery disease and congestive heart failure are more often seen in older populations, the prevalence of heart disease in younger individuals is not uncommon.10 The first step when assessing a patient with chest pain in the wilderness is to determine if they have a known history of cardiac disease, or have cardiac risk factors. This helps determine the etiology of the patient’s symptoms.


Identification

Angina pectoris is chest pain that occurs from inadequate blood flow to heart muscle, most often due to a blockage within the vessels supplying the heart. The pain is often described as a squeezing, pressure-like sensation to the middle of the chest. It is sometimes associated with jaw pain, arm pain, diaphoresis, or nausea.11 Older individuals, those with diabetes, and females often present with atypical angina symptoms—their cardiac disease may present with nausea, weakness, or shortness of breath as the only symptom. Chest pain that occurs with exertion and improves with rest is termed stable angina. Unstable angina is pain that occurs at rest, usually described as severe, and often occurring in a crescendo-like pattern.12 While any angina is concerning in a wilderness environment, unstable angina is considered a medical emergency and needs to be immediately evacuated to a hospital setting.

Myocardial infarctions (MIs) occur when blood flow to the heart muscle is blocked, causing tissue ischemia and cell death. Often patients will have symptoms classically described as crushing, heavy, pressure-like substernal chest pain. Other patients may be asymptomatic, or experience mild or atypical symptoms from their MI. Once the heart muscle dies, it no longer functions and may cause dysrhythmias due to abnormal electrical conduction over damaged myocardium. This can lead to malignant arrhythmias such as ventricular tachycardia or ventricular fibrillation. It can also lead to poor myocardial squeeze and decreased cardiac output, resulting in cardiomyopathy and congestive heart failure.13

The leading cause of congestive heart failure (CHF) in the United States is coronary artery disease and myocardial ischemia. CHF can originate as either right ventricular or left ventricular dysfunction, but ultimately leads to poor heart squeeze and fluid backup in the heart, lungs, and peripheral vasculature. Clinically, this most commonly manifests as lower extremity edema, pulmonary edema, orthopnea (shortness of breath while lying flat), and dyspnea on exertion. CHF can be managed as a chronic condition, controlled with medications such as antihypertensives, rate controlling agents, and diuretics,14 and only becomes a problem when it becomes “decompensated,” meaning the body’s metabolic demands outweigh the heart’s ability to function. A person who has well-controlled CHF may find themselves with worsening heart failure symptoms if they exert themselves at altitude or in extreme environments, where the heart has to work harder than it is capable of doing.

Another medical emergency that causes chest pain is aortic dissection. The aorta is comprised of three layers—the intima, media, and adventitia. A dissection occurs when a tear in the intima allows blood to enter the media layer. The high pressure of this blood then propagates along the media, creating a false lumen with a weakened wall (Figure 22.1). The most common causes are hypertension and connective tissue disorders such as Marfan’s syndrome. A thoracic aortic dissection will classically present with severe, tearing chest pain, radiating to the back.11,15
Often the patient will have extremely high blood pressures and more than 20 mm Hg measured systolic blood pressure differences between the upper extremities. Aortic dissection should be considered in any patient who presents with chest pain and an associated neurologic complaint such as upper extremity numbness or weakness, as dissections can disturb the blood flow to arteries supplying the central nervous system, creating both chest pain and neurologic symptoms.






FIGURE 22.1. Two Common Patterns of Aortic Dissection. Blood is pumped through the intimal tear to create a false channel with a weakened wall. From Morton PG, Fontaine DK. Critical Care Nursing. 11th ed. Philadelphia, PA: Wolters Kluwer; 2018.

The most extreme cardiac dysfunction that can occur is cardiopulmonary arrest. Cardiopulmonary arrest occurs due to a wide variety of factors. Massive MI can lead to large territory cardiac muscle ischemia and pump failure. Fatal arrhythmias can develop due to underlying cardiac disease, heart failure, medications, metabolic disorders, and congenital cardiac abnormalities. Respiratory failure can lead to cardiopulmonary arrest by causing hypoxemia, which in turn leads to severe metabolic derangements and ultimately inability to sustain cardiac function.

The major causes of cardiopulmonary arrest can be remembered with the pneumonic of “the Hs and Ts.” These include Hypoxia, Hypovolemia, Hypothermia, Hydrogen ion (acidosis), Hypo/hyperkalemia, cardiac Tamponade, Tension pneumothorax, Toxins, Thrombosis (MI), Thromboembolism (pulmonary embolism), and Trauma. The cause of cardiopulmonary arrest is most often based on the history and particular situation. If someone has sustained a traumatic injury causing hemorrhagic shock, the most likely cause of his or her arrest is hypovolemia, which is unlikely to respond to on-scene cardiopulmonary resuscitation (CPR). If a patient was complaining about calf swelling and chest pain with breathing prior to his or her collapse, pulmonary embolism becomes a likely culprit. Unfortunately, in the wilderness setting, most of these conditions change from potentially reversible to likely fatal, as they are highly time and resource dependent. Screening for risk factors and prevention of these conditions is therefore of much higher yield than carrying defibrillators or performing CPR in the wilderness.



Treatment and Disposition

Treatment of any cardiac condition begins with the basics of airway, breathing, and circulation. All providers should be able to recognize the warning signs of impending cardiac pathology and to initiate treatment.


FIRST AID

First aid providers should begin treatment by assessing the patient. When a person complains of chest pain, shortness of breath, appears pale, cool, clammy, and diaphoretic, the first step is to stop whatever the patient is doing, and have him or her sit down and rest. Attempt to take a set of vital signs (at a minimum check for pulse, respiratory rate, and estimate systolic blood pressure based on pulse pressure—requiring no equipment) and recognize any abnormalities. Any vital sign abnormalities should be documented and rechecked frequently while determination of proper evacuation method is initiated.


BASIC LIFE SUPPORT

The basic life support (BLS) provider should also frequently assess vital signs and be prepared to provide supportive care as needed. If symptoms are concerning for MI, give four tablets of 81 mg chewable aspirin. Patients presenting with signs of decompensated heart failure such as worsening dyspnea, orthopnea, or significant extremity swelling or signs of aortic dissection need to be evacuated immediately to the nearest hospital for further evaluation.


ADVANCED LIFE SUPPORT

For those with more advanced training such as advanced cardiac life support (ACLS), you are dependent on the equipment and medications present. For patients with signs or symptoms of MI or heart failure, give aspirin, establish intravenous (IV) access, monitor clinical exam including vital signs, resuscitate as needed, and evacuate rapidly. Patients with a suspected aortic dissection need IV access, close blood pressure monitoring, and evacuation.


CLINICIANS

Similar to advanced life support (ALS) providers, clinicians are also dependent on the equipment and medications present. If a patient appears to be having signs of a MI, give 324 mg chewable aspirin. For patients with signs of decompensated heart failure, medications that may be beneficial include diuretics such as furosemide and vasodilators such as nitroglycerin to reduce preload and afterload. For patients with signs of aortic dissection, blood pressure control and rapid evacuation are essential. 12-lead
electrocardiogram (ECG) capability is becoming increasingly miniaturized and portable, and some WEMS systems have begun deploying ECG-capable machinery into the field. If an ST-segment elevation MI (STEMI) is identified, and access to the nearest percutaneous interventional facility for catheterization is known to be greater than 2 hours, some systems are electing to administer thrombolytics in the wilderness setting. All medications need to be given with extreme caution in the wilderness, as they have the potential to cause clinical decline without appropriate monitoring and resuscitative equipment.

For any level of provider, if you encounter a patient in the wilderness in cardiopulmonary arrest, assess their level of responsiveness, determine if the patient is breathing, and if the patient has a pulse. If he or she does not have a pulse, begin CPR. The American Heart Association (AHA) guidelines currently recommend providers initiate CPR in a C-A-B (circulation-airway-breathing) approach to minimize delay in compressions in order to provide adequate circulation of blood to the brain.16 If an automated external defibrillator (AED) device is available, attach the pads to the patient as soon as possible, taking care to minimize interruptions in chest compressions, and follow the instructions on the device. The AHA guidelines recommend early defibrillation, as it can reduce morbidity and mortality associated with cardiac arrest. It is critically important in a wilderness setting to remember this approach does not apply in lightning strike or drowning subjects, as rescue breaths should be delivered immediately in these conditions. Care of lightning patients and drowning patients is discussed in more detail in Chapters 18 and 16, respectively. Assistance or definitive care may be hours away; therefore, when considering CPR in the wilderness, one must weigh the risks to the rescuer(s) versus the potential outcome and benefit to the patient. Someone who has had a massive heart attack, is in cardiac arrest, and is multiple hours away from definitive care, may be unlikely to survive this event. If they do survive, their outcome is likely to be far more severe in morbidity than if it had occurred close to definitive care. If there is a potentially reversible cause of arrest, such as hypoxia, hypovolemia, or tension pneumothorax, and there are resources available to treat those accordingly, these measures can be life saving. However, providing prolonged CPR can be both physically and emotionally exhausting to the rescuer. CPR in a wilderness setting may be discontinued after 30 minutes if the patient does not have return of spontaneous circulation. The potential exception to that 30-minute time frame is a hypothermic patient, as decreased body temperature is neuroprotective, thus patients may have partial, if not full, neurologic recovery despite a prolonged resuscitation. Again, the rescuer must weigh the risk of prolonged CPR to the providers, especially in a cold environment. In the wilderness, CPR should not be initiated for patients with obvious signs of death (rigor mortis, lividity, decapitation), frozen chest wall, ice in the airway, submersion in cold water for longer than 60 minutes, and any situation that would put a rescuer in excessive danger.17



Respiratory/Shortness of Breath

Respiratory emergencies are commonly encountered in a wilderness setting. Many people have underlying respiratory diseases, which can limit exercise tolerance or be exacerbated by environmental factors. In addition, respiratory infections can be potentially life threatening if not recognized and treated.


Identification

Asthma is one of the most common respiratory conditions. In 2014, the Centers for Disease Control (CDC) found that 8.6% of all U.S. children (defined as younger than 18 years of age) and 7.4% of all U.S. adults (defined as older than 18 years of age) are currently diagnosed with asthma.18 The condition
is caused by chronic bronchial inflammation that limits airflow and can lead to airway obstruction. Asthma is identified by the presence of wheezing, a prolonged expiratory phase, and diminished air movement on auscultation. A patient experiencing an asthma exacerbation will often complain of shortness of breath and chest tightness. In severe exacerbations, patients may be tachycardic, tachypneic, and speaking in short sentences due to difficulty breathing. Even patients with well-controlled asthma can experience exacerbations in a wilderness setting. A prospective study of 203 wilderness travelers with known asthma showed that 43% experienced an asthma attack while engaging in a wilderness activity.19






FIGURE 22.2. ACLS pulseless arrest algorithm. Adapted from Cardiac Arrest Algorithm: Algorithms for Advanced Cardiac Life Support 2017. ACLS Training Center website. www.acls.net/aclsalg.htm. July 27, 2017 and Neumar RW, Otto CW, Link MS, Kronick SL, Shuster M, Callaway CW, Kudenchuk PJ, Ornato JP, McNally B, Silvers SM, Passman RS, White RD, Hess EP, Tang W, Davis D, Sinz E, Morrison LJ. Part 8: Adult Advanced Cardiovascular Life Support. Circulation. 2010;122:S729-S767.

Chronic obstructive pulmonary disease (COPD) is a condition of limited air movement that occurs either secondary to diminished elasticity of the alveoli (emphysema) or chronic inflammation of the airways (chronic bronchitis).20 The most common cause of COPD is long-term tobacco use, but other causes such as interstitial lung disease and α-1-antitrypsin deficiency can cause similar symptoms. Most patients are aware of their chronic lung conditions, but this should also be suspected in those with a history of long-term cigarette smoking. Similar to asthma, wheezing, prolonged expiration, and diminished air movement can also be appreciated in COPD. Patients experiencing a severe COPD exacerbation may present with pursed lip breathing, cyanosis, agitation or anxiety, and tripod positioning (bent over with hands on knees to help with breathing). Environmental allergens, altitude, infections, and increased exercise can all exacerbate COPD symptoms.

The respiratory tract can be divided into upper (nares, nasal cavity, oropharynx, larynx) and lower (trachea, bronchi, bronchioles, alveoli). Both upper respiratory infections (URIs) and lower respiratory infections such as pneumonia can be problematic in a wilderness environment. URIs are most commonly caused by viruses and are often referred to as “the common cold.” Symptoms can include cough, congestion, rhinorrhea, sinus pain, fever, and sore throat. Pneumonia can present similarly to URIs and it can be difficult to differentiate between the two clinically. Classically, pneumonia presents with fever, cough productive of green or yellow sputum, and “crackles” on lung auscultation (Figure 22.3). Both viruses and bacteria can cause pneumonia. Bacterial pneumonia often needs evaluation and possibly treatment in a hospital setting, as these patients may require supplemental oxygen and have a potential to decompensate and become systemically ill without timely and appropriate antibiotic treatment.

A pulmonary embolism (PE) is a blood clot that travels (most often from deep leg veins) to the pulmonary blood vessels.
Blockage in the pulmonary vessels causes a mismatch between ventilation and perfusion in the lung sections supplied by the occluded vessels. The incidence of PE has been reported to be approximately 60 to 70 per 100,000 individuals.21 Certain populations are predisposed to thromboembolic disease such as those with clotting disorders, recently postoperative patients, those on estrogen or other hormone replacement therapies, cancer patients, and pregnant women. PE often presents with chest pain on inspiration, termed pleuritic pain. When the blockage is large or obstructs a major pulmonary vessel, it can cause significant heart strain, hypoxemia, and cardiopulmonary arrest. Indicators of possible PE are shortness of breath, pleuritic chest pain, unilateral leg swelling (indicating deep vein thrombosis), tachycardia, hypoxia, and pulseless electrical activity leading to cardiopulmonary arrest.






FIGURE 22.3. Chest radiograph of a right middle lobe pneumonia (marked by arrows). From Webb WR, Higgins CB. Thoracic Imaging. 3rd ed. Philadelphia, PA: Wolters Kluwer; 2017.

Another cause of sudden respiratory distress is a spontaneous pneumothorax. A pneumothorax occurs when air becomes trapped in the pleural space and creates increased pressure on the lung, causing a “collapsed lung.” Most often, these are encountered in the setting of trauma. However, a pneumothorax can occur spontaneously, caused by a ruptured air sac in the lung, termed a “bleb.” These most often occur in young, thin males and in patients with underlying lung disorders such as COPD/emphysema. A pneumothorax presents with sudden onset of dyspnea and diminished breath sounds to the affected side. If a pneumothorax becomes large enough, increased pressure in the pleural cavity will shift the mediastinum away from the affected side causing a tension pneumothorax (Figure 22.4). This can cause compression of the superior vena cava and decreased diastolic filling in the heart, leading to decreased cardiac output. Clinically, patients present with tracheal deviation, absent breath sounds on the side of the pneumothorax, and Beck’s triad (jugular venous distention, hypotension, and muffled heart sounds).






FIGURE 22.4. Open Pneumothorax (top) and Tension Pneumothorax (bottom). During inspiration air enters the pleural cavity. In an open pneumothorax, air exits during expiration. In a tension pneumothorax, air is unable to exit; creating increased intrathoracic pressure and subsequent shifting of the mediastinum. From Grossman SC, Porth CM. Porth’s Pathophysiology: Concepts of Altered Health States. 9th ed. Philadelphia, PA: Wolters Kluwer Health Lippincott Williams & Wilkins; 2014.



Treatment and Disposition

Treating a respiratory emergency in the wilderness can be a very stressful experience, since many of the diagnostic and therapeutic tools medical providers are accustomed to having may not be available (such as supplemental oxygen, chest radiographs, and advanced airway equipment).


FIRST AID

Basic first aid goals are to recognize worsening respiratory status, attempt to remove whatever exacerbating factor is causing the symptoms, and determine if the patient needs immediate transport to a higher level of care. If someone with a known history of asthma is having shortness of breath, encourage home medication (such as albuterol) administration to help with these symptoms.


BASIC LIFE SUPPORT

For BLS providers, the goals of care are to provide supplemental respiratory support when possible, such as oxygen and albuterol, and recognize when patients need to be evacuated to a higher level of care.


ADVANCED LIFE SUPPORT

ALS providers can intervene most aggressively in respiratory distress if medications and other equipment are available. For asthma and COPD patients, bronchodilators and steroid medications are indicated. If there is concern for PE or pneumothorax, the provider should ensure the patient has adequate IV access and close monitoring of vital signs and respiratory status until hospital evaluation. If there is concern for a tension pneumothorax, the ACLS provider can perform needle decompression (Figure 22.5) and obtain an advanced airway if needed.

Oct 16, 2018 | Posted by in EMERGENCY MEDICINE | Comments Off on General Management of Medical Conditions in the Wilderness
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