Management of Infectious Diseases



Management of Infectious Diseases





PART 2: General Infectious Diseases in the Wilderness Environment

Christopher Davis

Howard K. Mell


INTRODUCTION

Treatment of infectious diseases has become a routine practice in medicine. It is easy to take the lifesaving impact of timely administration of antibiotics for granted. The introduction of mass-produced penicillin during World War II had a profound impact on both amputations of limbs due to gangrene, as well as death from overwhelming infections caused by dirty battlefield wounds. Since that time, the number of antimicrobial choices has exponentially increased, but new antibiotic-resistant species are emerging constantly. Traditional EMS has only recently began to place emphasis on the treatment of infectious disease, primarily because rapid transport to hospitals is the norm, and the time delay, in most cases, is not significant enough to outweigh the benefit of access to advanced diagnostic and treatment resources in the emergency department. Providers of wilderness EMS, however, must be able to recognize disease patterns, anticipate the projected clinical course, and provide early intervention when possible to prevent clinical deterioration. As increasingly portable and robust technology makes the wilderness feel less remote and intimidating to some, and more people venture into the wild every year, wilderness EMS providers will need to be prepared to encounter patients with a variety of diseases. Due to variable disease progression, patients who felt fine when leaving home can quickly develop serious illness once in the wilderness, especially if they have underlying medical conditions.



Scope of Discussion

The field of infectious disease is vast and this chapter is by no means an exhaustive review of all possible serious infections one may encounter while rendering care in the wilderness. It is possible that nearly any infection that one could see in traditional EMS could also occur in the wilderness. Out-of-hospital
medicine is inherently limited by, and in essence defined by, a lack of advanced diagnostic equipment, support, and resources. Wilderness EMS relies on physical exam, clinical history, and knowledge of epidemiology to guide treatment. This leads to quite a bit more uncertainty, and differentiating similar infections may not be possible without bacterial cultures, gram stains, and the support of a microbiology lab that one would have in a hospital emergency department. Although similar diseases may be indistinguishable to the wilderness EMS provider, by using a systematic approach it is possible to initiate appropriate treatment early and prevent patient deterioration. This chapter will cover recognition and treatment of the most common and life-threatening infections of the skin and soft tissue, gastrointestinal (GI) system, genitourinary (GU) system, central nervous system (CNS), and pulmonary system. Finally, this chapter covers sepsis and its management in the wilderness.


EPIDEMIOLOGY

Management of infectious diseases relies on general understanding of disease prevalence in populations. In general, the population venturing into the wilderness is somewhat healthier and younger than the population at large. In traditional EMS it is common to treat patients with severe infections. The actual incidence of illness due to infectious disease in the wilderness is unknown, as statistics reflecting the prevalence and nature of calls for help in the wilderness are scarce, and there is no central repository for reporting. The National Park Service reports that approximately 280,000,000 people a year visit national parks, though only 1.8 million stay overnight in the backcountry, and 2.96 million in park campsites.1 Between 2012 and 2013, there were approximately 35 to 40 calls for EMS per million visitors to national parks, with the majority being for traumatic injuries. Approximately 46% were for noncardiac medical complaints.2 It is unclear how many of these calls involved infections, or whether they occurred in the frontcountry or backcountry. While the data are not entirely representative of all travelers to other backcountry areas such as National Forests or other public lands (the National Park System includes a considerable amount of frontcountry and even some urban areas), it does show an overall trend toward a lower utilization of EMS and likely overall healthier population group, who are engaging in activity more likely to cause injury than illness.

Although the prevalence of infectious disease is less common for wilderness EMS providers, the impact of infectious disease is far more profound than in the frontcountry. Traditional EMS providers typically would not need to consider treating a urinary tract infection (UTI) or pneumonia, but this may be necessary in the wilderness. Pneumonia, for example, is typically very straightforward to treat in an otherwise healthy person. A visit to an outpatient clinic or an emergency department with access to testing and expert clinicians makes diagnosis fairly simple. Treatment can be tailored to the patient with many antibiotic choices to account for allergies and likely organisms. The same healthy patient in a wilderness environment is much more complicated to manage. Progression of illness will make self-evacuation difficult due to shortness of breath, and could exponentially increase the time to diagnosis and treatment if that required arriving at a hospital. Wilderness EMS crews will likely have limited choices in antibiotics which may make it difficult to account for every disease and patient-specific allergy. Providers will need to be equipped to diagnose and treat evolving infections without all of the resources considered common in the hospital environment. Early recognition and treatment prevents otherwise mild infections from progressing to life-threatening or fatal processes.


CLINICAL MANAGEMENT OF PULMONARY INFECTIONS


Identification

Infections of the pulmonary system are common and range in severity from very mild to life-threatening. Although travelers to wilderness areas are at risk of a variety of diseases uncommon in the frontcountry, they are still much more likely to suffer from the same infections that are common in the frontcountry. Infections of the pulmonary system are classified by the anatomic location of the infection, and have characteristic physical exam findings and symptoms.

Bronchitis is one of the most common ailments seen in clinical medicine. It is the infection of the bronchi, or large airways of the lungs. It is usually caused by viruses, and by definition, is self-limited in course. Patients present with at least 5 days of dry cough, sometimes with sputum production, wheezing, and can have mild dyspnea with exertion. Bronchitis has an indolent course and usually has a gradual onset, worsening over days. Patients with bronchitis may also have cough productive of rust-colored or blood-tinged sputum, which is a result of inflammation and irritation of the bronchioles by persistent coughing. During the first few days of illness it is not possible to distinguish acute bronchitis from other viral upper respiratory infections caused by the common cold or related viruses. Patients who are smokers or have underlying lung disease such as chronic obstructive pulmonary disease (COPD) or asthma are more likely to have severe symptoms, and can have acute exacerbations of their disease triggered by the inflammation caused by infection.

Pneumonia is the acute infection of the lung parenchyma, the portions of the lung involved in gas transfer—the alveoli and small bronchioles. It is distinct from bronchitis in both presentation and significance. While bronchitis may cause annoying symptoms by irritating the large airways and causing cough, pneumonia can cause difficulty with gas exchange leading to severe shortness of breath and even hypoxia. Pneumonia is characterized by relatively rapid onset of fever, chills, cough, malaise, and shortness of breath. Approximately 30% of patients will experience chest
pain. Pneumonia often follows a viral illness in otherwise healthy adults. Sudden shortness of breath (or worsening of earlier mild shortness of breath), high fever, and rapid respiratory rate in a patient who has been suffering from cold symptoms for several days should be an alert that a patient is developing pneumonia. In contrast to bronchitis, pneumonia is typically a bacterial infection, although viruses can cause pneumonia as well.

Pneumonia is classified as either community-acquired pneumonia (CAP) or health care-associated pneumonia (HAP) depending on the clinical context. Patients with significant contact with the health care system are classified as health care-associated, including3:



  • Intravenous (IV) therapy, wound care, or IV chemotherapy in the past 30 days


  • Residing in a nursing home or long-term care facility


  • Hospitalization for more than 2 days in the past 90 days


  • Attendance at hospital or dialysis clinic in past 30 days

Wilderness EMS providers are unlikely to encounter HAP patients in remote areas, but it is important to note that they are more likely to be infected with different organisms than patients with CAP, and will need different antibiotics.

Pneumonia is a common, potentially life-threatening condition that is usually of little concern in otherwise healthy patients in the traditional EMS context. Standard practice in hospital-based medicine is to obtain chest x-ray to confirm the diagnosis of pneumonia. Wilderness EMS providers will need to rely on history and physical exam findings to make the diagnosis and begin treatment; however, there are no specific sets of clinical symptoms that can reliably distinguish pneumonia with complete certainty. Additionally, exposure to common wilderness factors, such as mold and mat, produce conditions that mimic pneumonia. While the vast majority of patients with pneumonia are febrile (80% according to some studies), accurate measurement of the patient’s temperature in the wilderness is difficult, and can be affected by the environment. Exposure to a cold environment can lower the patient’s core temperature and mask a fever, just as exertion and exposure to heat can raise the core temperature. Portable pulse oximetry is relatively inexpensive and units are available that are small and lightweight (Figure 20.2.1). These units measure pulse oximetry (SpO2,) a surrogate but usually accurate reflection of arterial oxygen saturation (SaO2). A significant drop in the patient’s pulse oximetry reading during ambulation or lower than expected readings accompanied by fever, rapid respirations, and cough are also strongly suggestive of a severe pneumonia warranting intervention. On examination, most patients will also have audible crackles on lung auscultation. Despite much investigation, no constellation of symptoms has ever been shown to reliably predict whether a patient has pneumonia.4 An assessment of the overall risk of treatment versus that potentially leaving a bacterial pneumonia untreated should accompany the decision to begin therapy. While bronchitis is self-limited and unlikely to incapacitate a patient, pneumonia can progress to a life-threatening and incapacitating illness fairly quickly without treatment. Prior to antibiotics, this was a leading cause of death in human populations.






FIGURE 20.2.1. Low-cost portable pulse oximeter


Treatment and Disposition

Treatment of respiratory illness can be thought of in three parts: support of the patient’s breathing and respiratory function, treatment of underlying organism causing illness (if possible), and relief of symptoms. Not all patients suffering from respiratory illness and infections will require rapid evacuation or even antibiotics. In general, treatment by wilderness EMS providers should start with careful risk-assessment considering:



  • Degree of respiratory distress (examples of worsening respiratory distress include increased work of breathing, decreased SpO2, and rapid respiratory rate)


  • Underlying lung disease such as COPD or asthma


  • Signs of poor perfusion (examples include pale skin, lack of urine output, tachycardia, slow capillary refill)


  • Speed of progression: symptoms rapidly worsening over the course of hours instead of days

If in doubt, rapid evacuation should be initiated for patients at high risk of deterioration or with rapidly progressive illness. When the situation allows, beginning treatment and evacuating early is preferable when the patient is still able to assist in his or her own rescue.


Basic Life Support

Providing supplemental oxygen by nasal cannula or nonrebreather mask is fundamental basic life support (BLS) care for nearly all respiratory complaints. While providing supplemental oxygen may be possible and necessary in wilderness EMS, providers must use a more measured approach than in the frontcountry. Standard practice is to provide supplemental oxygen by nasal cannula at 2 to 4 liters per minute (lpm), or high-flow oxygen
by nonrebreather mask at 10 to 15 lpm based on subjective degree of difficulty breathing. While short-term application of high-flow oxygen in otherwise healthy patients has little risk, there is evidence that, at least in patients with COPD, titrating oxygen therapy to patient response and pulse oximetry may improve mortality.5,6,7 The biggest problem with oxygen delivery in the wilderness is physically delivering an adequate supply of compressed oxygen to the patient due to the weight and size of oxygen tanks. In general, high-flow oxygen by mask should be avoided if possible. Providers should start with lower flows of oxygen than is usual in frontcountry EMS, and titrate oxygen rate of delivery to patient response. There is no need to raise a patient’s SpO2 to 100%. A goal of 92% to 94% is safe and adequate in patients with respiratory infections, as saturations less than 92% have been associated with poor outcomes, and over-oxygenation has been shown to be harmful, even in patients with such severe disease as to require intubation.1,2,3,4 Small adjustments to the flow of oxygen not only significantly increase the percentage of inhaled oxygen (FiO2), but also dramatically shorten the life of the tank (see Table 20.2.1). It is important to note that as altitude increases, atmospheric pressure decreases, which makes it more difficult to diffuse oxygen into the blood. SpO2 is normally lower in healthy people at altitude, and the degree that it is lowered is relative to the altitude. Providers can check the SpO2 of themselves and other healthy rescuers and compare it with that of the patient to get a better idea of the severity of respiratory function compromise.


Advanced Life Support

In addition to providing supportive care, the introduction of advanced life support (ALS) personnel allows wilderness EMS teams to begin therapeutic interventions typically reserved for the hospital environment. Upper respiratory infections often cause bronchospasm. On exam, patients will have characteristic wheezing breath sounds and shortness of breath. Albuterol, a beta-agonist bronchodilator, works by relaxing bronchiole smooth muscle to relieve bronchospasm. It is often delivered by nebulization with compressed air, or more commonly in frontcountry EMS, compressed oxygen. It is more commonly used by patients at home in the form of a metered dose inhaler (MDI). Many clinicians believe that nebulized albuterol is superior to MDI; however, head-to-head trials have failed to show any superiority in patients who are able to use them properly.8 Nebulized albuterol should therefore not be used unless the patient is too dyspneic (short of breath) to take a full breath to effectively use the MDI. This will save oxygen, which is usually in limited supply in wilderness environments.








Table 20.2.1 Hours of Oxygen Delivery by Tank Size and Flow Rate

























































Flow Rate (L/min)


Tank Sizea


1


1.5


2


2.5


3


4


5


6


ML 6


2.8


1.9


1.4


1.1


0.9


0.7


0.6


0.4


C


4.0


2.7


2.0


1.6


1.3


1.0


0.8


0.7


D


6.9


4.6


3.5


2.8


2.3


1.7


1.4


1.2


E


11.4


7.6


5.7


4.6


3.8


2.8


2.3


1.9


a For more information about oxygen cylinder size conventions, see http://bit.ly/oxygen_cylinders.


Steroids are familiar to ALS providers in traditional EMS. They are commonly used to reduce systemic inflammatory response in asthma attacks, COPD exacerbations, and allergic reactions. There is some evidence that steroids may improve mortality when given to patients with CAP.8,9,10,11 Steroids should be considered for patients with significant symptoms concerning severe bronchitis or pneumonia. They have a clear role in reducing inflammation and improving outcomes in COPD and asthma exacerbations, and the actual diagnosis may be unclear to the wilderness EMS providers. There is no significant difference in the effectiveness of IV or oral steroids, so IV formulations should be reserved for patients who are unable to take pills by mouth due to severe respiratory distress, nausea and vomiting, or altered mental status. There is no clear evidence to suggest that any particular steroid-dosing regimen is superior. Prednisone 50 mg by mouth once daily or methylprednisolone (SoluMedrol) 0.5 mg/kg may be given IV every 6 to 12 hours.

State medical boards approve mediations for use by EMS personnel, and there is significant variability among states as to the legality of EMS personnel initiating antibiotic therapy without direct physician involvement. Some states such as Maine and North Carolina do permit the development of wilderness-specific treatment protocols allowing for antibiotic administration. Patients suspected to have pneumonia could be started on antibiotics if rapid evacuation is not feasible. Table 20.2.2 summarizes antibiotic recommendations for CAP.


Clinician

Integrating physicians, PAs, and APRNs into wilderness EMS systems allows for a more nuanced approach to the management of respiratory infections in the wilderness. Most physicians, PAs, and APRNs involved in traditional EMS are very familiar with managing respiratory infections from their usual clinical practice. Some additional consideration must be given to the possibility of mold or dust-induced respiratory inflammation as well as to other environmental causes of pulmonary compromise as these are more common in the wilderness setting. Treatment protocols should be developed that maximize the number of indications for which a single drug may be used. This limits the number of drugs that must be carried saving space, weight,
cost and minimizing complexity of decision-making. It would be reasonable to include only levofloxacin, doxycycline, and ceftriaxone in the formulary, and still be able to provide adequate respiratory coverage. All three antibiotics are useful for treatment of infections from various other organ systems, and the protocol could still account for drug allergies. It may not be feasible to carry multiple antibiotics, and one must consider the specific characteristics of the team’s practice environment and the demographics of the patients they are likely to encounter. For those teams needing a single antibiotic solution to as many conditions as possible, we recommend ceftriaxone as parenteral therapy and levofloxacin or clindamycin for oral therapy.








Table 20.2.2 Suggested Antibiotics























Recommended Antibiotics for Pneumonia in the Wilderness


Able to tolerate pills by mouth, no signs of poor perfusion, hypoxia or RR #30




  • Azithromycin 500 mg first day, 250 mg daily days 2-5


OR if allergy to macrolide (azithromycin, erythromycin)




  • Doxycycline 100 mg daily


Not able to tolerate pills by mouth OR signs of severe disease




  • Levofloxacin 750 mg IV (or PO if able to tolerate) daily


OR if allergy to fluoroquinolone (levofloxacin, ciprofloxacin [Cipro], or moxifloxacin [Avelox])




  • Ceftriaxone 1 g IV/IM daily PLUS EITHER



  • Azithromycin 500 mg IV (or PO if able to tolerate) OR if allergy to macrolide (azithromycin, erythromycin)



  • Doxycycline 100 mg PO daily


Adapted from IDSA/ATS guidelines for recommended empiric antibiotics for community acquired pneumonia in adults in Mandell LA, Wunderink RG, Anzueto A, et al. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis. 2007;44 Suppl 2:S27-72, by permission of the Infectious Diseases Society of America.




CLINICAL MANAGEMENT OF GENITOURINARY INFECTIONS


Identification

Complaints of painful urination (dysuria), urinary urgency, flank pain, vaginal or penile discharge, and lower pelvic/suprapubic pain are suggestive of GU infections. Depending on the severity of the illness, patients may also have fever, chills, tachycardia, or rapid respirations. As with all infections, signs of poor perfusion, altered mental status, and low blood pressure are signs of very severe infection and portend a poor outcome in the wilderness.

Lower UTIs, also known as cystitis, are quite common in females, but relatively uncommon in men. Approximately 5 to 8 otherwise healthy men per 10,000 will experience a UTI yearly, compared to 1 in every 2 or 3 otherwise healthy women.12,13 Young women who complain of a combination of dysuria, suprapubic pain, urgency, and hematuria are likely to have UTIs. Women of childbearing age should be screened for pregnancy. The diagnosis is usually confirmed by urinalysis—in the wilderness, necessarily, by urine pregnancy dipstick rather than serum testing. With regard to UTI, the presence of leukocyte esterase with or without nitrites, microscopic evaluation of the urine for bacteria and white blood cells, and urine culture combined with symptoms of UTI is the gold standard for diagnosis. Urine smell is often associated with UTIs by both patients and clinicians; however, it is reflective of hydration status and is of no utility in determining whether a patient has a UTI.14 Dipsticks are small and easy to carry; however, it is not necessary to confirm the UTI diagnosis with urine dipstick to begin treatment in nonpregnant, otherwise healthy females without vaginal complaints. The likelihood of a UTI in these patients is 90% and with vaginal complaints is still 50%.15 The only utility of urine dipstick in this case would be that if negative, it may suggest investigating other causes, or potentially conserve limited supplies of antibiotics.

Patients presenting with the symptoms of UTI who also have flank pain and/or fever may be suffering from an upper UTI, also known as pyelonephritis. Bacteria can travel from the bladder to the kidneys via the ureter and infect one or both kidneys. On exam, patients may have pain with percussion of the costovertebral angle (Figure 20.2.2), fever, and tachycardia. Although most otherwise healthy patients do very well if treated early for pyelonephritis, long delays in initiation of antimicrobials can lead to patient decompensation. Given the relatively low incidence of UTIs in men, one should strongly consider other diagnoses before settling on pyelonephritis in an otherwise healthy male. Intermittent sharp pain in flank, which may radiate to the groin, accompanied by blood in the urine should raise the suspicion for a kidney stone. If this patient also has a fever, this does constitute an emergency, as infected kidney stones can lead to serious complications and patients can quickly become very sick.







FIGURE 20.2.2. Costovertebral angle (CVA) tenderness can be elicited by percussing the patient’s back at the junction between the spine and the lowest ribs, which roughly corresponds to the location of the kidney.

Complaints of vaginal pain, discomfort, foul-smelling discharge, and suprapubic discomfort indicate that the patient may be suffering from gynecologic infections. Risk factors include being sexually active, and not using barrier protection. Mild infections are limited to the cervix, and generally do not produce severe symptoms. Chlamydia and gonorrhea are common sexually transmitted infections in developed countries. These infections can ascend to infect the uterus, fallopian tubes, ovaries, and surrounding pelvic structures. This is known as pelvic inflammatory disease (PID). Patients with risk factors who complain of symptoms of gynecologic infections, and who have significant lower abdominal pain, tenderness, and or fever should be treated as though they have PID. The diagnosis is typically made by a speculum examination of the cervix and digital examination of the internal reproductive organs. This is very uncomfortable for the patient, is beyond the scope of practice of most wilderness EMS providers, would add little useful information in the wilderness EMS context, and is not routinely recommended for the diagnosis of gynecologic infections in wilderness EMS.

It is critically important to consider ectopic pregnancy when evaluating any female of childbearing age complaining of pelvic pain. This is a potentially immediately life-threatening condition that should warrant emergent evacuation. A negative urine pregnancy test makes the diagnosis of ectopic pregnancy highly unlikely.


Treatment and Disposition

Treatment of GU infections is relatively less complex than pulmonary infections, and in general, they are less likely to be the primary reason for wilderness EMS calls.


Basic Life Support

For some patients suffering lower UTIs, urination may be very painful. The pain from uncomplicated UTIs may be alleviated somewhat with phenazopyridine. It is available over-the-counter (OTC) under various names including Pyridium, Azo-Gesic, and Baridium. It works as a local anesthetic to the lining of the urethra that can help relieve the symptoms of a UTI. It is important to note that it will turn the patient’s urine a reddish-orange color. This may be the only treatment needed for an uncomplicated UTI in a patient who will be able to access definitive medical care within a day or two.

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Oct 16, 2018 | Posted by in EMERGENCY MEDICINE | Comments Off on Management of Infectious Diseases

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