Consistent Approaches to Procedures and Practices in Neonatal Hematology

Background

The optimal hemoglobin concentration needed by neonates, under various physiologic and pathologic circumstances, has not been completely elucidated. It is likely that some NICU patients benefit from erythrocyte transfusion, but reports have varied regarding precisely how to identify these patients. We judge that the trigger value at which an erythrocyte transfusion is ordered for a NICU patient should vary according to the clinical situation. For consistency, we have adopted the following

Background

Thrombocytopenia is one of the most common hematologic problems among sick neonates, affecting 25% to 30% of all patients admitted to a NICU. Approximately one third of those patients are treated with platelet transfusions. In fact, a recent historical cohort study performed in our NICU showed that 9.4% of all neonates admitted in a 2-year period received platelet transfusions, and 52% of these received more than one. The great majority of those platelet transfusions were given

Background

Neutrophil transfusions (also referred to as granulocyte transfusions) are used infrequently in neonatology. Animal experiments show conclusively that neutrophil transfusions can improve the survival rates of septic, neutropenic, neonatal, and adult subjects. Practical problems with the rapid procurement and administration of neutrophil concentrates, however, severely limit their usefulness. Efforts to overcome this limitation by storing neutrophils have not been successful, but the ability to

Background

IVIG has two principal uses in clinical medicine: (1) as a source of specific antibody, to prevent infections in patients with low antibody concentrations; and (2) as a means of inducing temporary nonspecific reticuloendothelial blockade, to prolong the circulation of immunoglobulin-coated blood cells.

Extremely low–birth weight neonates ([ELBW] <1000 g) generally have very low circulating IgG concentrations, because most of the maternal-fetal IgG transfer occurs after 32 weeks' gestation. The

Background

In the United States, rG-CSF is produced exclusively by Amgen (Thousand Oaks, CA). Neupogen is the Amgen trademark, and filgrastim is the generic name selected for rG-CSF). Filgrastim has been approved by the Food and Drug Administration (FDA) for use in patients with severe chronic neutropenia, and also for three other indications: (1) cancer patients receiving myelosuppressive chemotherapy, (2) cancer patients receiving bone marrow transplantation, and (3) patients undergoing peripheral blood

Background

In the United States, recombinant erythropoietin (rEpo) is licensed by Amgen (Thousand Oaks, CA) as Epogen, and by Ortho Biotech (Raritan, NJ) as Procrit. rEpo is a 165–amino acid glycoprotein with a molecular weight of 30.4 kd and is produced by mammalian cells into which the human Epo gene has been introduced. It has the identical amino acid sequence of the isolated natural human Epo. It is supplied as single-dose vials of 2000, 3000, 4000, and 10,000 U/mL and as multidose vials of 10,000 and

Background

Neutropenia is a frequent occurrence in the NICU. As many as 8% of patients admitted to NICUs develop neutropenia at some time during their hospitalization (Fig. 3).

Approach to the Neonate with Neutropenia

The approach to the neonate with neutropenia varies depending on the severity and duration of the neutropenia. When an ANC is less than 500/μL, we repeat the test immediately. If the repeat is also less than 500/μL, we follow the algorithm in Figure 3.

Background

Leukemoid reactions occur in as many as 1% to 2% of patients in the NICU. Transient elevations in blood neutrophil concentration can be classified kinetically as the result of either (1) accelerated neutrophil production, (2) accelerated release of neutrophils from the bone marrow into the blood, (3) neutrophil demargination, or (4) diminished egress of neutrophils from the blood into the tissues. Leukemoid reactions in the NICU are likely to be transient, not associated with hyperviscosity,

Background

Eosinophilia is a common diagnostic dilemma in the NICU. It is frequently disregarded or overlooked, however, because its significance and causative mechanism are not known (Fig. 5).

Causes of Eosinophilia

Reported causes of eosinophilia in the NICU include (1) fungal or bacterial infection; (2) idiopathic hypereosinophilic syndrome; (3) antibiotic usage; (4) exposure to antigens in parenteral nutrition, catheters, or blood products; (5) chronic lung disease; (6) maternal ingestion of l-tryptophan supplements during

Presentation of Thromboses

Thromboses may present as the following:

• 1

  Infarction, particularly nonhemorrhagic (cerebral, renal)

• 2

  Swelling of limb, face, or body area supplied by a vessel containing an intravascular catheter

• 3

  Abdominal mass, hematuria, unexplained thrombocytopenia

• 4

  Purpura fulminans or limb necrosis

• 5

  Chylothorax

• 6

  Sudden, unexplained respiratory decompensation, particularly in a patient with a prior thrombosis

• 7

  Persistently dusky extremity or extremity part (toe, foot, or finger)

• 8

  Line dysfunction (e.g., line not

Background

Ten to 15 patients per year in our NICU undergo a bone marrow biopsy procedure as part of the clinical (nonresearch) evaluation of a cytopenia. These procedures are almost always for the purpose of evaluating severe neutropenia or thrombocytopenia. As part of an overall attempt toward consistency of practice, the following approach is provided for ordering a marrow biopsy.

The Purpose of a Marrow Biopsy

In evaluating a cytopenia, a marrow biopsy can aid in determining whether the condition has resulted from diminished

Monitoring the Thrombus

Once the diagnosis of a thrombus has been made, serial monitoring is essential, regardless of treatment modality used. Ultrasound and echocardiography are less sensitive for thrombus detection, but also less invasive than angiography for ongoing monitoring. Echocardiography is useful for intracardiac thrombi and most inferior vena cava and superior vena