Page 910 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 69: Human Immunodeficiency Virus (HIV) and AIDS in the Intensive Care Unit 641

body fluids. In a prospective study, multivariate analysis identified prevalence of HIV and hepatitis C within hospitalized patients is likely
three independent predictors of mycobacteremia in patients with significant—a cross-sectional prevalence study at a tertiary care hospital
CD4 counts of less than 50 cells/mm : (1) fever for 30 days during in Germany found that the prevalence of HIV infection in hospital-
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the previous 3 months, (2) serum albumin concentration of less than ized patients was 5.3%—15-fold higher than the general population.
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3.0 g/dL, and (3) hematocrit of less than 30%. When applied pro- Needlestick injuries are a common workplace occurrence—an estimated
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spectively to a validation set, the presence of at least one of the three 300 to 800,000 occurred annually in the United States in 1998. After
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predictors had high sensitivity (94%), modest specificity (42%), and a single accidental needle stick exposure to contaminated material, the
modest positive predictive value (30%). 159 rate of seroconversion to HIV is approximately 1 per 300 exposures, or
0.3 percent. Risk factors for seroconversion were evaluated in a case-
Management: A three-drug combination of clarithromycin, etham-
butol, and rifabutin significantly improved survival (median = 8.6 vs control study and include visibly contaminated needles/devices, the
device being used directly in an artery or vein, and a deep injury.
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5.2 months; compared to a four-drug regimen of ciprofloxacin,
rifampin, ethambutol, and clofazimine) and eradication of myco- Prompt risk assessment postinjury and initiation of postexposure pro-
phylaxis with antiretroviral therapy reduce the risk of seroconversion by
bacteremia in a randomized controlled trial (Table 69-4). Adverse 168
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effects of rifabutin included uveitis, which occurred much less often at least 80%. Guidelines for the management of occupational exposure
recommend the use of a standard combination regimen of three agents
at a daily dose of 300 mg (6%) compared with 600 mg (38%). Results
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from a randomized trial of combination therapy for MAC bacteremia for high-risk exposures for a 28-day period postinjury, with close moni-
toring for potential toxicities.
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indicated a survival benefit for a regimen containing clarithromycin
500 mg bid compared with 1000 mg bid. In a randomized trial,
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Chaisson and coworkers reported higher mortality among patients SUPPORTIVE CARE FOR AIDS PATIENTS IN THE ICU
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receiving clofazimine (61%) compared with placebo (38%, p = 0.032)
in combination with clarithromycin and ethambutol. Resuscitation and supportive care of AIDS patients in the ICU includes
At present, rifabutin may not need to be added routinely to clarithro- airway protection, noninvasive ventilation, mechanical ventilation,
mycin/ethambutol for treatment of AIDS-related MAC bacteremia. In a cardiovascular monitoring and support, gastrointestinal and nutritional
comparison of dual versus triple therapy including rifabutin, no clinical management, and psychological supportive care. Airway assessment is
benefit was observed. However, among those who responded to therapy, important in patients who have a depressed level of consciousness, usu-
subsequent development of clarithromycin resistance occurred in 2% ally because of neurologic problems or systemic sepsis, and in patients
(1 of 44) and 14% (6 of 42) who received rifabutin and placebo, respec- who have acute respiratory failure. Detailed discussion of the manage-
tively (p = 0.055). Nonetheless, the significance of the protective effect ment of acute hypoxemic respiratory failure is presented in Chap. 43.
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of rifabutin on subsequent clarithromycin resistance is doubtful in the In general, patients with arterial hypoxemia require supplemental
ART era because long-term survival and subsequent MAC bacteremia high-flow, high-concentration oxygen. If hypoxemia is refractory to
relapses are related primarily to immune reconstitution rather than supplemental oxygen, then mask continuous positive airway pres-
continued clarithromycin susceptibility of the MAC isolate. sure (CPAP) of 5 to 10 cm H O may improve arterial hypoxemia and
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Primary prophylaxis of MAC is indicated for patients with CD4 decrease respiratory rate in alert patients who are able to protect their
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counts below 50 cells/mm (see Table 69-5). A randomized compara- airway. Mask CPAP has been used for up to 11 days. Pneumothorax
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tive study indicated that azithromycin 1200 mg once weekly is a more occurs infrequently, in approximately 5% of patients. Mask CPAP also
effective prophylactic than rifabutin 300 mg daily, in addition to being allows speech and therefore ongoing discussion regarding prognosis and
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less expensive and less problematic with respect to drug interactions. therapeutic options. Noninvasive ventilation using BiPAP may also pre-
Clarithromycin is also effective for MAC prophylaxis; however, when clude the need for intubation and mechanical ventilation. Endotracheal
breakthrough mycobacteremia occurs, 29% to 58% of MAC isolates are intubation and mechanical ventilation are indicated in patients who
clarithromycin resistant. MAC drug resistance has not been a problem require airway protection, or who do not respond to CPAP or BiPAP.
among failures of rifabutin prophylaxis and was observed in only 11% Assist-control ventilation with positive end-expiratory pressure is usu-
of azithromycin failures. The desire to preserve clarithromycin as an ally necessary for PCP patients who require mechanical ventilation.
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active drug for treatment of MAC bacteremia provides the rationale for In patients who meet the criteria of ARDS, lung-protective venti-
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restricting its use as an alternative prophylaxis drug. Primary prophy- lation with a tidal volume of 6 mL/kg of ideal body weight is recom-
laxis for MAC bacteremia may be discontinued if there is a sustained rise mended because this decreases the mortality of ARDS from 40% to 30%
in the CD4 count to more than 100 cells/µL for at least 3 months (see (ARDSnet). It is recommended to use the ARDSnet protocol, which
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Table 69-5). Both primary and secondary prophylaxis may be discontin- includes titration of positive end-expiratory pressure (PEEP) and FiO 2
ued after documentation of immune reconstitution. according to a simple algorithm. Use of higher PEEP generally is not
recommended because of the risk of barotrauma (especially in PCP) and
HIV INFECTION CONTROL AND POSTEXPOSURE because a randomized, controlled trial of higher PEEP versus “usual”
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PROPHYLAXIS PEEP found no significant improvement in mortality.
Critically ill AIDS patients may develop cardiovascular instability.
It is important to emphasize that HIV is not transmitted through casual Systemic arterial catheterization is appropriate for continuous arterial
contact. This is particularly reassuring for the families and health care pressure monitoring and arterial blood gas determinations. Hypotension
providers of AIDS patients. Within the hospital setting, the advent of has many causes, including hypovolemia, autonomic neuropathy, pentami-
HIV and similar blood-borne pathogens has led to the evolution dine, or septic shock. Hypovolemia may be caused by increased insensible
of practices designed to reduce the risk of transmission to health care fluid losses, diarrhea, and inadequate intake. Autonomic neuropathy occurs
workers, that is, universal precautions. At present implementation of in some AIDS patients and appears to explain the occasionally sudden
Isolation Precautions practices within the health care system begins with fatal hypotension and bradycardia. The hypotension that may occur
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the assumption that blood and certain bodily fluids from any patient during infusion of pentamidine can be minimized by administering the
could be infectious in nature. As such, Standard Precautions require the drug slowly over 4 hours, as described earlier. Hypotension in critically
use of personal protective equipment (gloves/gown/possible face shield) ill AIDS patients may be the result of septic shock owing to bacterial
when interacting with blood, bodily fluids, nonintact skin, and mucus sepsis (eg, pneumococcus, H. influenzae, Staphylococcus, or enteric
membranes of patients. Current guidelines also detail steps required gram-negative bacilli), PJP, or other systemic fungal infection such as his-
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to reduce the risk for work-place needle stick injuries. Appropriate toplasmosis. Patients who have PJP, similar to patients who have bacterial
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education regarding these practices is important within the ICU as the sepsis, have tachycardia, decreased systemic vascular resistance, increased
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