Respiratory Infections Flashcards
Croup
-Definition: ( AKA Laryngotracheitis) inflammation of the larynx and trachea.
-Etiology: Predominantly viral
-MC: Parainfluenza virus*
-Other common viruses: RSV, Adenovirus
-Pathogenesis: spread via respiratory droplets
-Common cause of ED visits in children*
-marked swelling in subglottic region of larynx
-Children 6 mos-3 yrs of age, rare beyond age 6
Risk Factors:
-Peaks in fall and early winter
-Close contacts-daycare etc.
Sxs:
-Initially -> nasal congestion, coryza
-Within 12-48 hrs develop:
-fever -stridor -barking cough* -hoarseness
-Sxs may worsen at night
-Should resolve w/in 1 week
-Rapid progression to respiratory distress should prompt you to think of other DDx
-discharge home
-If sxs do not improve/worsen->admit
Epiglottitis
-Definition: rapidly progressing form of cellulitis of the epiglottis and surrounding structures EMERGENCY!
-Can be life-threatening secondary to progressive airway obstruction
-Etiology: Bacterial (H. influenzae, Staph aureus, Group A strep, S. pneumnoniae, H. parainfluenzae)
-Hib vaccine has substantially reduced incidence of H. influenzae in children (developed countries)
-Spread via respiratory droplets
-children (peak age 3 to 5 yrs old)
Risk factors: -unvaccinated for Hib
Sxs:
-feverish -severe ST -drooling -+/-respiratory distress (stridor, dyspnea) -Appears toxic
-Tripod position. -Sniffing position -Drooling. -Stridor -“Hot potato” voice -Sternal retractions. -Tachycardia. -Oropharynx appears less severe than sxs
-Often based on hx and physical-> DON’T WASTE TIME!
-Laryngoscopy if in operating room (cherry red epiglottis)
-Do NOT do laryngoscopy in clinical setting to avoid spasm and airway compromise.
-Lateral neck x-rays (enlarged epiglottitis-“thumbprint sign”)
-Labs can reveal leukocytosis, +blood cultures
Tx:
-Most importantly-SECURE AIRWAY. -Do NOT observe* -Send to ED immediately! -IV Abx to cover most likely microorganism -Abx should be continued for 7-10 days -*If household contacts include unvaccinated child < 4 yrs old-prophylactic Rifampin should be given to all members of the household x 4 days.
Bronchiolitis
-Serious respiratory illness in infants/young children characterized by wheezing and airway obstruction resulting in inflammation of bronchioles
-Leading cause of hospitalization in infants/young children (< 2 yrs old)
-Respiratory Syncytial Virus most common cause (~70%)
-MC in children < 2yrs old (peak 2-6 mos)
-Late fall through winter
RF’s:
-older siblings -daycare -passive smoke exposure -Native Americans -household crowding
RF’s for severe disease/complications: -premature, low birth weight -age <6-12 wks -chronic pulmonary disease -congenital heart disease -congenital/anatomical defects
Sxs:
-fever (1-2 days) -rhinorrhea -cough
Followed by….
-wheezing -tachypnea -respiratory distress
Sxs peak on days 5-7 then gradually resolve
-fever (initially) -crackles. -cough -apnea -rapid respirations -mild hypoxemia -nasal flaring -grunting -cyanosis -retractions -exp. wheezing -dehydration -Otitis media
-Based on hx and physical
-Can be supplemented w/labs and xray
-Nasal wash of respiratory secretions (recommended method)
-Others: rapid antigen test, immunofluorescence, RPR
-CXR: not indicated if- afebrile, not in respiratory distress, symmetrical findings on exam
-CXR usually reveal non-specific findings (hyperinflation, peribronchiolar cuffing, atelectasis)
Most children treated in outpatient setting*. -Educate parents on anticipatory guidance -expected course
-when to return etc.
-Supportive care: -fluids -nasal suction -Can consider inhaled bronchodilators but not done routinely for outpatient
Hospitalization required if:
-hypoxemia on room air. -history of apnea -feeding difficulties. -marked respiratory distress. -dehydrated or lethargic -toxic appearance. -parent unable to carefully observe
Pertussis
- Definition: acute bacterial infection of the respiratory tract
- Pertussis=“whooping cough”
- Highly contagious-attack rates of 80-100% among unimmunized household contacts
- Cyclic outbreaks tend to occur q 3-5 yrs
- Etiology: Bordatella pertussis (secretes toxins that destroy ciliated epithelial cells)
- Spread via respiratory droplets
- Peaks-preschool yrs (unimmunized populations)
- Peaks- infant morbidity and death
Pertussis 3 phases
Incubation period of approx. 7-10 days Sxs: (3 phases) 1. Catarrhal phase: (lasts 1-2 wks, difficult distinguishing from common cold) -coryza -lacrimation -mild cough -low-grade fever -malaise 2. Paroxysmal phase: (lasts 2-4 wks) -frequent/spasmodic coughing episodes that occur during a single expiration (sev/hour -> 5-10/day) -posttussive vomiting -audible whoop at end of episode -interrupted sleep -fever is uncommon (suggests superinfection) 3. Convalescent phase: (1-3 months) -cough becomes less severe/less frequent
Pertussis PE findings
Catarrhal:
-low grade fever -cough -lacrimation -conjunctival injection
Paroxysmal:
- cough -audible whoop
- +/-neck-vein dist.
- bulging eyes
- tongue protrusion
- cyanosis
Convalescent:
-lingering cough
Pertussis Dx
-In the setting of an outbreak or known close contact to confirmed case a cough lasting > 2 weeks is sufficient
-In a non-outbreak setting the choice of test depends on the duration of sxs
- < 4 wks of cough w/clinica suspicion-> nasopharyngeal culture and PCR -> 4 wks -> serology to detect Abs
Nasopharyngeal culture: (aspiration or swab)
-Gold standard for diagnosis*
-Highly specific, lacks sensitivity
-Takes 5+ days for results
PCR (polymerase chain reaction):
-Recommended in combination w/cx
-Specific and sensitive
-Results often available within 1 day
-More expensive
Pertussis Tx
- Antibiotics: (given to all pts if suspected)
-Drug of choice-Macrolides (i.e.-Azithromycin)- Supportive care:
-Infants and older children w/severe disease should be hospitalized
-Possible role for inhalers
-No role for cough suppressants* - Hospitalized patients-respiratory isolation
Children may return to school/daycare:
-After 5 days on antibiotics OR
-If not treated, 21 days after onset of sxs
Antibiotic prophylaxis recommendations: - Close contacts: (keep a low threshold)
-Face to face exposure w/in 3 ft of symptomatic pt
-Direct contact w/ respiratory/oral/nasal secretions of symptomatic pt
-Sharing same confined space in close proximity of symptomatic pt for > 1 hour
Antibiotic Prophylaxis recommendations:
- Supportive care:
- Individuals at high risk for complicated pertussis
-Infants < 1 yr old
-Persons w/immunodeficiency
-Persons w/underlying comorbidities (i.e.- Chronic lung disease, CF)
-Women in 3rd trimester of pregnancy
Influenza
-Definition: a highly contagious acute respiratory infection caused by influenza viruses, often severe
-Etiology: Influenza A, B, and C
-Transmitted by respiratory droplets, fomites
-Incubation period of approx. 18-72 hrs
-Influenza A & B-major human pathogens
NOT THE STOMACH FLU!
Type A:
-yearly, most “flu” epidemics
-affects humans, animals (birds, pigs)
-divided into subtypes based on surface glycoproteins ( H, N)
Type B:
-yearly, less widespread than A
-affects humans only
Type C:
-mild respiratory illness, not epidemics
Each year:
-the new flu vaccine is a mixture A & B strains from previous year
-a slightly new strain evolves based on changes to H and N proteins
Antigenic shift:
-major antigenic variations, abrupt change in H or N proteins, associated w/pandemics/outbreaks
Antigenic drift:
-minor antigenic variations/mutations on RNA that occur over time, in between pandemics
H1N1
- Originally referred to as “swine flu”-thought to have similar genes as influenza virus that affected swine (N.America)
- Studies later revealed-comprised genes from humans, avian, and swine (Europe, Asia)
- H1N1 officially diagnosed in humans in April 2009 but first case likely in Mexico-2008)
- June 2009-declared pandemic by WHO
- August 2012-pandemic declared over
- Continues to circulate as seasonal flu
- Annual flu vaccine best protection
Influenza Risk Factors
RF’s (for high risk complications):
- Children < 4 yrs old
- Adults >/= 65 yrs old
- Pregnant women
- Children < 19 yrs old on long-term ASA therapy (increased risk for Reye’s syndrome)
- Children/adults w/chronic disorders of pulmonary or cardiac systems
- Children/adults w/chronic metabolic diseases or immunodeficiency (DM, renal dis, HIV etc.)
- Residents of nursing homes/long-term facilities
Influenza sxs
(ABRUPT onset*)
-Headache -Fever/chills -Myalgias
-Malaise -Cough -ST
-Rhinitis
PE findings: (may be minimal- if uncomplicated)
-Fever- (100-104) higher over first 24 hours
-Flushed, hot skin
-Cough
-+/-erythema in oropharynx (often unremarkable)
-+/-mild cervical lymphadenopathy
-+/- wheezes, rhonchi
-In uncomplicated patients sxs typically improve over 3-5 days, resolve w/in 1-2 weeks
-Cough may persist for up to 2 weeks
Influenza Dx
- During an outbreak can be diagnosedbased on high clinical suspicion*
- Testing most useful if it will aid in tx plan
- Most commonly used test -> rapid antigen test (nasopharyngeal swab), qualitative (results available w/in 15 minutes)
- Most sensitive and specific test -> reverse-transcriptase PCR
- Other modalities available but less widely used (immunofluorescence, serology, viral culture)
Influenza Tx
- For uncomplicated influenza in pts at low risk for complications consider symptomatic measures first (rest, hydration, APAP,NSAIDS)
- Antiviral medications available IF started w/in 2 days of onset of illness
- helps to decrease severity/duration only
- Neuraminidase inhibitors ( A & B)
- Admantane agents (A)
Most commonly used: Oseltamivir (Tamiflu)*
- 5 day course reduces duration of sxs/signs by 1-1.5 days (if started w/in 2 days of onset*)
- H1N1 virus from 2009 was resistant to Tamiflu
- Amantadine or Rimantadine (only active against A)
- 3-7 day course reduces duration of sxs/signs by ~50% (if started w/in 2 days)
- Sensitive to H1N1 but resistance widespread overall
- Antibiotics should be reserved for bacterial complications only*
Influenza Vaccination
-Current recommendations: vaccinate entire population above the age of 6 mos*
Should be administered annually in the fall
1. Inactivated vaccine:
-50-80% protection expected if vaccine and circulating virus are related
-highly purified, safe, few AE’s (rare assoc. w/GB)
-avoid in pts w/egg allergy, ok for immunocompromised
2. Live attenuated vaccine:
-available as intranasal spray
-approved for use in healthy, non- pregnant individuals aged 2-49 yrs old
-Preservative free available in smaller quantities (removes Thimerosal-mercury based derivative)
Children < age 9 who receive the flu shot for the 1st time need a 2nd dose 1 month later*
You will NOT get the flu from the vaccine (inactivated)*
