Critical Care Issues in Older Adults

From Critical Care Issues in the Care of Older Adults: Managing Infections and Antimicrobial Resistance in Older Aduults, sponsored by the University of Michigan Medical School, Ann Arbor

Educational Objectives

The goal of this program is to improve management of influenza and infections in older adults. After hearing and as­similating this program, the clinician will be better able to:

1.   Describe characteristics of the H1N1 influenza virus that emerged in 2009.

2.   Use appropriate methods for the diagnosis of influenza.

3.   Select effective treatment for seasonal influenza.

4.   Evaluate patients in long-term care facilities for urinary and respiratory tract infections.

5.   Determine causes of skin and soft tissue infections in patients in nursing homes.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose. Dr. Falsey presents information in her lecture that is related to off-label or investigational use of a ther­apy, product, or device.

Acknowledgements

Drs. Falsey and Bradley spoke in Ann Arbor, MI, at Critical Care Issues in the Care of Older Adults: Managing Infections and Antimicrobial Resistance in Older Adults, presented September 24-25, 2009, by the University of Michigan Medical School. The Audio-Digest Foundation thanks the speakers and the University of Michigan Medical School for their cooper­ation in the production of this program.

Influenza

Ann R. Falsey, MD, Professor of Medicine, University of Rochester, School of Medicine and Dentistry, Roches­ter, NY

Influenza virus: enveloped RNA virus; classified as influenza A or B based on internal proteins; influenza A viruses subdivided based on surface proteins (hemagglutinin [H] and neuraminidase [N]); segmented genome allows shuf­fling of genes; hemagglutinin  —  16 types; »1000 molecules per virus; attachment protein for virus; host receptor is sialic acid residues (species-specific); requires cleavage for activity; agglutinates red blood cells (RBCs) in culture; major target of serum neutralizing or protective antibody; neuraminidase  —  9 types; »100 molecules per virus; im­portant for budding and release of virus; less important target for neutralizing antibody; hosts  —  birds (eg, ducks, migratory geese) central in perpetuating flu worldwide; humans; pigs can be infected with human and avian strains, which allows recombination of viruses; many new viruses originate in rural Asia; current strain emanating from Mexico; classification  —  3 types of hemagglutinin (H1, H2, and H3) affect humans; 2 types of neuraminidase (N1 and N2) affect humans; virus classified by group (A or B), location where virus first isolated (eg, California), year isolated, and subtype (eg, H3N2)

Antigenic changes: drift  —  point mutations in neuraminidase or hemagglutinin; usually minor variations; population still partially immune; results in annual seasonal influenza epidemics; shift  —  gene reassortment; virus acquires new hemagglutinin or neuraminidase protein; population no longer immune; results in influenza pandemics

Pneumonia and influenza mortality: fourth leading cause of hospitalization; sixth leading cause of death (mostly in older adults); usual increase in wintertime mortality associated with other respiratory viruses (eg, coronavirus, re­spiratory syncytial virus [RSV])

Influenza epidemics: sharp peaks and excess mortality; H3N2 viruses primarily affect older adults; usually last 6 to 8 wk; 1918  —  Spanish flu; H1N1 swine-variant virus; circulated for »40 yr; 1957  —  double replacement in surface proteins; H2N2 virus emerged; 1968  —  single replacement of hemagglutinin; H3N2 virus (Hong Kong flu) emerged; 2009  —triple reassortment; H1N1 (swine flu) reemerged; young children (eg, infants, children 2-4 yr of age) affected; infection less common in older (>65 yr of age) adults, and generally mild; symptoms typical, but with more gastrointestinal (GI) symptoms (50% of patients have nausea and vomiting); highly transmissible in af­fected populations

Current H1N1 virus and older adults: H1N1 swine-variant virus circulated in United States from 1918 to 1957; people 52 to 91 yr of age likely to have partial immunity; people born after 1957 likely to have been affected by H2N2, H3N2, and H1N1 virus that began in 1977 (Russian flu; does not resemble current H1N1 swine flu); study  —  looked at people born in or earlier than 1915; found 100% of people 91 to 101 yr of age (ie, 2-12 yr of age during Spanish influenza epidemic) had high (1:562) neutralizing antibody levels; cells isolated to make functional monoclonal antibodies to swine influenza; impact  —  staff illnesses expected in long-term care facilities and hospi­tals; infections in children of staff; absenteeism; in New York, influenza vaccine mandatory for all health care workers; concerns about increased resistance to oseltamivir (Tamiflu)

Seasonal influenza: death and hospitalization rates higher in older adults, even though incidence of influenza illness highest in school-aged children and young adults; effect of underlying diseases  —  study found death rate 9 per 100,000 in patients >65 yr of age; 100 per 100,000 with congestive heart failure (CHF), 240 per 100,000 with chronic obstructive pulmonary disease (COPD), and 870 per 100,000 with both CHF and COPD; vaccination im­portant

Presentation of disease: abrupt onset; fever; myalgia; conjunctival irritation; sore throat; nasal congestion; cough; in older adults, symptoms often more subtle and fever may be absent (70% have low-grade fever); patients with stroke or cognitive problems often cannot articulate symptoms

Other viruses: RSV and coronavirus peak in winter; human metapneumovirus (“looks a lot like RSV”) circulates in late winter and early spring; parainfluenza virus

Clinical features for diagnosis: healthy older adults tend to have more classic symptoms; in older adults with mar­ginal heart failure or COPD, consider influenza when patient decompensates (ie, clinical picture may be dominated by heart failure); adult with respiratory illness who requires hospitalization during winter (including pneumonia); clinical features not ideal for diagnosing influenza; study found no single or set of clinical parameters reliably dis­tinguished influenza from other viruses; triad of cough, temperature ³38ºC, and illness <7 days 78% sensitive and 73% specific for contagious influenza (ie, patients antigen- and culture-positive); RSV  —  runny nose; wheezing; influenza  —  high fever; aches; symptoms of RSV and influenza overlap (need test for specific diagnosis)

Rapid tests: immunofluorescence not widely available; enzyme immunoassays (EIAs)  —  simple; results available in 15 to 30 min; specificity good when influenza prevalent (false-positive results rare); sensitivity problematic; »1000 plaque-forming units of virus in secretions needed for positive result; negative test result does not rule out influ­enza; may detect only influenza A or B, or both

Viral culture: gold standard; results available in 3 to 7 days; strain typing distinguishes H1 from H3 viruses; can be followed with resistance testing

Polymerase chain reaction (PCR): highly sensitive and specific; results available in 3 to 4 hr; can distinguish sub­types of influenza; can be designed to detect drug resistance based on genetic changes; disadvantages  —  expensive; contamination problems and false-positive results; not widely available

Serology: results available in 6 wk; can be useful in retrospective investigations of outbreaks

Positive test results: culture-positive patients sick for »2.5 days; culture-negative and antigen-positive patients sick for »3 days; PCR-positive but culture- and antigen-negative patients sick for »6 days; patients who are seropositive only sick for »1 wk; highly febrile patients more likely to be culture-positive; patients with low-grade fever more likely seropositive only; good specimen required for rapid testing, culture, or PCR (rub cotton swab in nose gently but firmly; combine with throat swab)

Antiviral therapy: older therapies  —  amantadine and rimantadine “not very useful anymore”; effective for treatment and prophylaxis against influenza A; H3N2 viruses (primarily affect older adults) nearly 100% resistant; frequent central nervous system (CNS) side effects (eg, confusion); inexpensive; newer therapies  —  oseltamivir and zanami­vir (neuraminidase inhibitors); effective against influenza A and B; fewer problems with resistance; zanamivir must be inhaled (important for patients with asthma or COPD; can worsen bronchospasm); oseltamivir (oral) approved for treatment and prophylaxis; seasonal H1N1 virus (affects mostly younger patients) sensitive to rimantadine and zanamivir, but resistant to oseltamivir; seasonal H3N2 resistant to rimantadine, but sensitive to oseltamivir and zanamivir; zanamivir effective for all influenza types; efficacy  —  about the same in sensitive patients; reduces dura­tion of symptoms by »1 day; decreases shedding; in older patients with underlying disease, reduces symptoms by »3 days; complicated influenza  —data suggest oseltamivir associated with lower risk for in-hospital mortality in pa­tients >65 yr of age; >50% of patients sick longer than recommended time (48 hr) for start of antiviral therapy; sick patients with high clinical suspicion and patients with positive rapid test results may be treated on day 3 or 4

Secondary bacterial infections: little data on which patients with influenza need antibiotics; consider stopping anti­biotic therapy in patients sick for »2 days with positive rapid test results and clear chest x-ray

Influenza vaccine in older adults: efficacy controversial; as vaccine coverage increased from 15% in 1980 to 65% in 2001, age-adjusted mortality remained flat; consider bias in studies (eg, healthy-user bias, “better doctor” bias); efficacy depends on immunocompetence of patient, match between circulating and vaccinating strain, and age of patient; improving vaccine  —  increase dose; add adjuvants; intradermal delivery; new vaccines; increasing antigen amount in standard vaccine shown to have significant benefit for antibody response in older patients (questionable whether this translates to better protection)

Infection control: influenza spread by aerosol route; use of standard surgical mask when within 3 ft of patient and frequent handwashing recommended; transmissibility in hospitalized patients  —  study found that at 5 days, 50% of patients (mean age, 76 yr) had culturable virus based on shell vial and tube culture (20% at 7 days); effect of age on quantity of influenza RNA in nasal secretions  —   multivariate analysis showed age >65 yr associated with longer clearance time (ie, viral positivity); further recommendations for infection control  —  vaccinate staff; keep up-to-date with community surveillance; institute rapid testing in emergency department; isolation depends on resources, rapid-test positivity, and high clinical suspicion; in long-term care facilities, educate staff, restrict visitors, and limit movements of infected patients; increase surveillance; antiviral treatment for ill patients and roommates; chemo­prophylaxis for entire institutions problematic

Evaluation of Fever and Infections in Nursing Home Patients

 Suzanne F. Bradley, MD, Professor of Internal Medicine, University of Michigan Medical School, Ann Arbor  

Long-term care facilities: goals include patient comfort and preserving or improving function; geriatricians define plan of care before transferring patients to nursing facility; commonly, ratio of registered nurses (RNs) to licensed practical nurses, 7:13 per 100 beds; full-time physicians present in »20% of facilities; physician input infrequent; when patients require transfer for offsite diagnostic procedures (eg, radiology), facility may not receive payment for services; important to decide when to transfer patients to acute care

When to suspect infection in long-term care facilities: 1) decline in functional status; new or increasing confu­sion, incontinence, falls, worsening mobility or oral intake, or change in cooperativeness; 2) presence of fever; when all patients with fever ³101ºF evaluated for infection, only 40% of infected patients detected; consider change in patient’s baseline temperature or lower fever threshold (99ºF-100ºF) as trigger to evaluate for infection; as baseline temperatures tend to be lower in geriatric population, fever threshold of 101ºF too high for this popula­tion

Evaluation: evaluate respiratory rate, hydration status, mental status, and organ systems; small studies suggest breathing rate of 25 breaths/min represents lower respiratory tract infection (RTI) 80% to 90% of time; no data about other vital signs (eg, tachycardia); likelihood of detecting RTI based on physical examination high (»93%); 80% of patients with documented RTI have cough, and 70% have rales “and perhaps some fever”

Sources of infection: pressure ulcers  —  consider in immobile patients; can develop quickly; diabetic patients more prone to skin and soft tissue infections; consider in patients with prosthetic devices, pacemakers, and prosthetic valves; indwelling Foley catheter  —  increases risk for bacteremia and urosepsis by nearly 40%; look for signs of de­hydration

Laboratory testing: if advance directives do not prohibit evaluation, determine whether patient should be transferred to hospital; complete blood cell count (CBC)  —  most useful test for evaluation of fever in long-term care facility; should be performed within 12 to 24 hr of onset; if white blood cell (WBC) count >14,000/μL, or left shift present, careful assessment for bacterial infection (even in absence of fever) should be performed; if negative and patient doing well, evaluation for bacterial infection may be discontinued

Urinary tract infection (UTI): if patient doing well but urine cloudy, and patient otherwise asymptomatic, no further assessment required; reasonable to evaluate symptomatic patients with no urinary catheter, who have fever, pain, blood in urine, worsening incontinence, or suspected impending sepsis; evaluate patients with urethral catheter, es­pecially if they have fever, rigors, delirium, or hypotension, and if catheter recently changed or evidence of urinary obstruction (obtain urine and blood cultures); noncatheterized men  —  obtain clean catch (midstream) specimen or use condom catheter; catheterized women  —  obtain catheter specimen; change indwelling urethral catheter before specimen collection; evaluation  —  urinalysis (UA) or dipstick initially; if patient has leukocyte esterase or signifi­cant pyuria on dipstick, obtain culture and perform susceptibility test; studies show treating patients with positive urine culture has no beneficial influence on morbidity, mortality, decrease in antibiotic use, or sense of well-being; also, treatment induces resistance and exposes patient to risk for side effects; pyuria  —  WBC count >10/μL on UA, or positive leukocyte esterase; 30% of well nursing home residents have significant pyuria; degree of pyuria does not help differentiate asymptomatic bacteruria and pyuria from true UTI; UTI unlikely in absence of WBCs, leuko­cyte esterase, and nitrates; symptoms  —  fever; costovertebral angle (CVA) tenderness (suggests pyelonephritis); dysuria (worsening or new), new frequency or urgency; new nocturia; worsening incontinence

Respiratory tract infection: pulse oximetry recommended (if O₂ saturation <90%, consider transferring patient); chest x-ray  —  useful for confirming diagnosis of pneumonia and identifying complications (eg, empyema, evidence of CHF, masses) in older adults; may predict need for hospitalization or impending mortality; detects 75% to 90% of pneumonia; purulent sputum specimen may help narrow antibiotic choices; alternative approaches include urine pneumococcal antigen, or Legionella antigen (detects only certain serotypes)

Skin and soft tissue infections: superficial swabs for treatment of suspected infection not useful; if patient does not improve with initial treatment, obtain deeper tissue (eg, soft tissue, bone); if osteomyelitis suspected, magnetic res­onance imaging best approach, but bone biopsy more specific; fungal infections  —  potassium hydroxide may help determine kind of infection and choice of drug therapy (eg, fluconazole [relatively benign], itraconazole, terbin­afine [associated with more drug interactions]); consider herpes simplex virus (HSV) and herpes zoster (obtain cul­ture or perform immunofluorescent antibody [IFA] or PCR test); scabies  —  consider in patients with unexplained rash; rule out before starting steroid therapy; most common causes of skin and soft tissue infections include group A streptococci and Staphylococcus aureus; obtaining tissue may be appropriate if patient not doing well or at risk for complications

Suggested Reading

Heukelbach J et al: Scabies. Lancet 367:1767, 2006; High KP et al: Clinical practice guideline for the evaluation of fever and infec­tion in older adult residents of long-term care facilities: 2008 update by the Infectious Diseases Society of America. Clin Infect Dis 48:149, 2009; Kaye KS et al: Utility of pulse oximetry in diagnosing pneumonia in nursing home residents. Am J Med Sci 324:237, 2002; Magaziner J et al: Prevalence and characteristics of nursing home-acquired infections in the aged. J Am Geriatr Soc 39:1071, 1991; McGeer A et al: Toronto Invasive Bacterial Diseases Network. Antiviral therapy and outcomes of influenza requiring hospital­ization in Ontario, Canada. Clin Infect Dis 45:1568, 2007; Mehr DR et al: Clinical findings associated with radiographic pneumonia in nursing home residents. J Fam Pract 50:931, 2001; Nicolle LE et al: Infectious Diseases Society of America; American Society of Nephrology; American Geriatric Society. Infectious Diseases Society of America guidelines for the diagnosis and treatment of as­ymptomatic bacteriuria in adults. Clin Infect Dis 40:643, 2005; Walsh EE et al: Clinical features of influenza A virus infection in older hospitalized persons. J Am Geriatr Soc 50:1498, 2002; Yu X et al: Neutralizing antibodies derived from the B cells of 1918 in­fluenza pandemic survivors. Nature 455:532, 2008.