Page 986 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 77: Management of the Critically Ill Traveler 717

■ AVIAN INFLUENZA hemorrhagic symptoms while only 25% of adults may have the same

Avian influenza A infections in humans have been increasing in inci- manifestations. The main bleeding sites are the skin and nose, with
gastrointestinal bleeding being uncommon. This clinical presentation
dence over the past decade. These infections are caused by avian
42
subtypes of influenza A, usually H5, H7, and H9. Most patients report needs to be differentiated from DHF. DHF is the most serious manifes-
tation of dengue virus infection and can be associated with circulatory
contact with sick or dead poultry, although a few human-to-human 54-57
cases of transmission have occurred. 43-46 Some subtypes present pre- failure and shock. The four cardinal features of DHF, as defined by
the World Health Organization (WHO), include increased vascular
dominately with conjunctivitis, but a number of H7 and most H5N1
subtypes present with a severe primary pneumonia with respiratory permeability (plasma leakage syndrome as defined by a hemoconcen-
tration [20% or greater rise in hematocrit]), pleural effusion, or ascites,
failure and ARDS. Respiratory failure with multiorgan damage is seen in
over 60% cases, and total mortality is over 60%. 43-49 Once admitted to the marked thrombocytopenia, fever lasting up to a week, and spontane-
ous bleeding. The physical examination in patients with dengue is
58
ICU with respiratory failure, the mortality exceeds 90%. Diagnosis is by
viral isolation and subsequent subtype identification by PCR in a patient generally nonspecific. The frequencies of fever and rash are noted above.
Injection of the conjunctiva, pharyngeal erythema, lymphadenopathy,
with appropriate clinical symptom and epidemiological risk factors.
Treatment is supportive with addition of a neuraminidase inhibitor as and hepatomegaly are present in up to half of patients. The rash is
typically macular or maculopapular and may be associated with pruritus.
outlined for use with the H1N1 pandemic. 47,48
Most cases are initially detected by the epidemiological link of con- Laboratory findings include leukopenia, thrombocytopenia, and elevated
54,57,59
tact with sick and dead birds. 23,24,50-52 Transmission is likely droplet, but liver enzymes. The gold standard for diagnosis is confirmation by
airborne has been proposed by some officials prompting higher levels serology. Confirmation of acute dengue virus infection is most frequently
accomplished using serology.
54,57,59
of protection. Once suspected, patients should be initially placed in 54,57,59
Patients with dengue
The treatment of dengue is supportive.
airborne isolation and all health care workers (HCWs) should wear fever should be cautioned to maintain intake of oral fluid to avoid dehy-
N-95 or other appropriate levels (PAPR) of protection. Cases of human-
to-human transmission have occurred among HCWs, but in all cases dration. Fever and myalgias can be managed with acetaminophen. The
most important measure to assist the patient with suspected dengue
the appropriate PPE was not used. 23,24,50-52 Finally, any suspected case of
avian influenza should prompt a call to local public health officials so fever is to carefully evaluate the patient for impending complications
or early evidence of DHF. Gastrointestinal bleeding, epistaxis, or men-
community measures to reduce spread can be instituted.
orrhagia in patients with DHF can be severe enough to require blood
transfusion. Significant internal bleeding may occur and could mask the
VIRAL HEMORRHAGIC FEVERS hemoconcentration seen with DHF, and in these cases, aggressive and
■ DENGUE massive blood product resuscitation is needed. Use of a histamine H
2
receptor antagonist or proton pump inhibitor is reasonable in patients
Current estimates suggest up to 100 million infections with dengue with gastrointestinal bleeding, although there is no evidence of benefit.
occur worldwide each year, and the dengue viruses (and subsequent Platelet transfusions have not been shown to be effective at preventing
dengue hemorrhagic fever [DHF]) are now arguably the most important or controlling hemorrhage, but may be warranted in patients with severe
arthropod-borne viruses from a medical and public health perspective. thrombocytopenia (<10,000/mm ) and active bleeding. Administration
3
53
Both epidemic and endemic transmission of dengue viruses is main- of intravenous vitamin K1 is recommended for patients with severe
tained through a human-mosquito-human cycle involving mosquitoes liver dysfunction or prolonged prothrombin time. Plasma leakage
of the genus Aedes. Humans become infected after being bitten by an in DHF is important to manage with intravascular volume repletion
infected female Aedes mosquito, and viremia in humans begins toward to prevent or reverse hypovolemic shock. In mild cases, particularly
the end of a 4- to 6-day incubation period. This viremia persists until when medical attention is received early, oral rehydration may be suf-
fever resolves, which is typically 3 to 7 days’ duration. An uninfected ficient. However, in patients with established intravascular volume loss,
Aedes mosquito may acquire the virus after feeding during a period of intravenous fluid administration is recommended. For patients with
60
viremia. The worldwide incidence of dengue and DHF has been increas- shock, initial resuscitation with normal saline or Ringer lactate, prefer-
ing in the past several decades, largely the result of human behaviors ably with 5% dextrose, is recommended, either as an infusion over the
such as population growth, poorly planned urbanization (overcrowding, first hour or as a bolus for patients in profound shock based on World
poor water distribution, and poor sanitation), modern transportation, Health Organization recommendations. A second infusion of an equal
changing lifestyles, such as increased reliance on plastic containers and volume is recommended in patients who remain in shock. A debate as to
tires (which increase standing water and thereby supporting mosquito whether crystalloids or colloids should be used for volume replacement
breeding), and most importantly, the lack of effective mosquito control. in critically ill patients with DHF currently exists. One large randomized
The typical clinical manifestations of dengue range from self-limited double-blind comparison of three fluids for initial resuscitation of 512
dengue fever to dengue hemorrhagic fever with shock syndrome. 54-57 Vietnamese children with dengue shock syndrome was performed.
60
Symptoms typically develop between 4 and 7 days after the bite of an Three hundred eighty-three patients with moderate shock were assigned
infected mosquito, although the incubation period may extend to 14 days. to Ringer lactate or one of two different colloid solutions: 6% dextran
Dengue can be excluded as the cause of symptoms in a traveler develop- 70 or 6% hydroxyethyl starch. One hundred twenty-nine patients with
ing an illness more than 14 days after returning from a dengue-endemic severe shock were randomized to receive one of the two colloids. The
country. The syndromes associated with dengue include dengue fever treatment regimen closely followed the WHO protocol above, with
(classic dengue), dengue with hemorrhagic manifestations, and DHF, 15 mL/kg administered over the first hour and 10 mL/kg over the second
the most serious and lethal form of dengue. 54-57 Classic dengue fever is an hour. The trial established that Ringer lactate was a safe, effective, and
acute febrile illness with headache, retroorbital pain, and myalgias and inexpensive alternative in initial resuscitation of patients with moder-
malaise with severe joint pain (“break-bone fever”). The fever lasts 5 to ate shock. In patients with severe shock, dextran and starch performed
7 days but a minority of patients display a biphasic (“saddleback”) fever similarly, although dextran was associated with more hypersensitivity
curve, with the second febrile phase lasting 1 to 2 days. 54-57 The febrile reactions. In addition, more recent studies evaluating starch-based col-
period may also be followed by a period of marked fatigue that can last loid infusions suggest worse outcomes in sepsis, and thus may need to
for days to weeks, especially in adults. be avoided.
Hemorrhagic manifestations occur commonly in patients with clas- Other adjuvant therapies have included steroids, although several
sic dengue fever, and in rare cases can be life threatening. In some trials have demonstrated that corticosteroids are no more effective
case series, up to 60% of children with dengue fever experience some than placebo in reducing death, need for blood transfusion, or serious

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