Page 871 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

602 PART 5: Infectious Disorders

Cancer patient
New onset of critical illness

Assessment for ICU admission

Premorbid PS poor (ECOG >2) Premorbid PS good (ECOG 2) New cancer diagnosis
Cancer not in control/remission Cancer in control/remission or Candidate for primary anticancer
Failure of anticancer treatment stable treatment

ICU admission not recommended Trial of ICU-based supportive ICU admission recommended
Symptom control/palliative care is care Resuscitation
recommended Mechanical ventilation
Vasopressor therapy
Antimicrobial therapy
Antineoplastic therapy
FIGURE 68-1. Algorithm for consideration of ICU services for cancer patients presenting with an acute critical illness.

blood measured in an automated blood cell counter. Since neutropenic fell below 0.5 × 10 /L. Therefore, with a falling neutrophil count, mul-
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patients with acute leukemia undergoing cytotoxic therapy frequently tiple observations over time are necessary to establish a pattern for the
have total WBC counts of <0.5 × 10 /L, neutrophils may be difficult to neutrophil profile and to estimate the relative infection risk. Survival of
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detect on a manually reviewed stained smear; accordingly, the range of an infection during severe neutropenia is also intimately linked to mar-
error for the procedure increases dramatically. Further, automated blood row recovery and recovery of the circulating neutrophil count. 23,24 The
cell counters may give misleading results when abnormal cells such as poorest outcomes for infectious episodes are observed among patients in
leukemic blasts of similar size as segmented neutrophils are present in whom the ANC continues to decline or fails to recover. 25,26
the circulation. This should dissuade the clinician from relying too heav- The duration of severe neutropenia (ANC <0.5 × 10 /L) is also related
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ily on a single ANC to judge the risk of infection. Rather, the clinical directly to infection risk. For example, bacteremic infections occur 3.5 and
relevance of the ANC lies in the recognition of the range associated with 5.4 times more often when neutropenia lasts 6 to 15 days and >15 days,
a specific infection risk. respectively. The duration of neutropenia is related to the degree
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The pattern of change of the ANC has also a significant independent of hematopoietic stem cell damage caused by the underlying disease
influence on infection risk. In an early study, 29% of the bacteremic epi- process and by myelosuppressive cytotoxic regimens. Following stem
sodes occurred as the neutrophil count was falling but before the ANC cell suppression, the peripheral neutrophil count falls at a rate directly
proportional to the size of the circulating and marginated peripheral
neutrophil pools and the size of the marrow storage pool of mature seg-
200 mented neutrophils. Marrow recovery follows the recruitment of com-
mitted stem cell precursors of granulocytic, monocytic, erythroid, and
180 megakaryocytic cell lines from the resting pluripotential stem cell pool.
Patients receiving pulse doses of chemotherapy on an intermittent
160
cyclical basis for solid tissue malignancies or lymphoreticular malignan-
140 cies sustain only temporary damage to the hematopoietic stem cell pool.
Number of infections 100 10 and 14. Although the neutrophil nadirs may be <0.5 × 10 /L, the
The expected circulating neutrophil nadir occurs generally between days
120
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duration of severe neutropenia is rarely longer than 5 to 7 days (median
3-5 days). For example, a patient receiving cyclophosphamide, doxo-
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rubicin, vincristine, and prednisone (CHOP) beginning on day 1 of a
80
21-day cycle of initial treatment for an intermediate- to high-grade non-
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Hodgkin lymphoma might develop a febrile episode on day 12 in associa-
tion with an ANC of 0.1 × 10 /L. The patient’s neutrophil count would be
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40 expected to have reached its nadir, and a rise in circulating neutrophils
20 would be predicted to occur between days 15 and 21. The likelihood that
this prediction is correct is increased if a relative monocytosis is observed
0 on the differential WBC count. The recovery of peripheral blood mono-
<0.1 0.1-0.499 0.5-0.999 >1.0 cytes precedes that of circulating neutrophils in chemotherapy-induced
Absolute neutrophil count
aplasia and often heralds the recovery of the ANC.
FIGURE 68-2. The relationship between the ANC and occurrence of infection in 98 patients In general, the more dose-intensive myelosuppressive regimens are
undergoing remission-induction therapy for AML. The proportions of the infections classified as associated with more hematopoietic stem cell damage and longer dura-
possible infection, clinical infections, nonbacteremic microbiologically documented infection, tions of neutropenia. Standard remission-induction regimens for acute
and bacteremic infection are shown. The greatest risk for infection occurs when the ANC is myeloid leukemia (AML) are composed of anthracycline drugs such
2
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<0.1 × 10 /L. Possible infections, brown bars; clinical infections, pink bars; nonbacteremic as daunorubicin administered in intravenous doses of 30 to 90 mg/m
microbiologically documented infections, beige bars; bacteremia, blue bars. daily over 3 days and an antimetabolite, cytarabine, administered as an

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