Page 2400 - Williams Hematology ( PDFDrive )

2370 Part XIII: Transfusion Medicine Chapter 138: Blood Procurement and Red Cell Transfusion 2371

27
morbidity in elderly patients at high cardiovascular risk. The rates of population ranging from 3 days old to 14 years of age. The trial enrolled
in-hospital complications were similar in the two groups. 626 patients who had Hgb less than or equal to 9.5 during their first 7
The Transfusion Requirements After Cardiac Surgery (TRACS) days in the pediatric ICU. The restrictive arm used a Hgb threshold of
trial randomized patients who underwent cardiac surgery with cardio- 7 g/dL, versus the liberal threshold of 9.5 g/dL. The restrictive group
pulmonary bypass into a liberal (Hct ≥30 percent) or restrictive (Hct received significantly fewer transfusions yet multiple-organ dysfunc-
23
≥24 percent) strategy for RBC transfusions. This noninferiority study tion syndrome (MODS) and mortality were almost identified in the two
found similar rates of 30-day all-cause mortality and severe morbidity. arms of the study. Thus, for critically ill children, a Hgb threshold of 7 g/
The number of transfused RBC units was found to be an independent dL could decrease transfusion requirements without increasing adverse
risk factor for complications or death at 30 days. outcomes.
Taken together, the evidence points to a Hgb threshold of 8 g/dL Three subgroup analyses were conducted with the TRIPICU data.
28
as a safe level to maintain most patients with a history of cardiovascu- One study analyzed postoperative patients, the second looked at pedi-
lar disease. Patients with acute coronary syndrome continue to be an atric patients after cardiac surgery, and the third examined patients
29
30
important exception for which current data is insufficient to support with sepsis. All three found no significant differences between new
any guidance. or progressive MODS or 28-day mortality in the restrictive and liberal
groups. However, all three studies suffered from small sample size and
RED BLOOD CELL TRANSFUSIONS could not draw strong conclusions because of insufficient power.
Trials in the neonate population have focused on premature babies
FOR ORTHOPEDIC PATIENTS and infants of very low birth weight. Unlike the clinical trials in adults,
The FOCUS trial, discussed above (see “Red Blood Cell Transfusions for where the results of all studies found that a restrictive transfusion
Cardiovascular Patients”), specifically identified patients with cardio- approach was as good as, or possibly superior to a liberal transfusion
vascular risk factors undergoing hip repair. Other studies with ortho- strategy, the results from clinical trials in neonates were mixed. One
22
pedic patients looked at more general outcome measures such as ability trial enrolled 100 preterm infants with birth weights between 500 and
31
to ambulate after hip surgery. One prospective study found a significant 1300 g. The transfusion thresholds in the restrictive and liberal arms
association between anemia and a decreased ability to walk indepen- were dependent upon the infant’s age and respiratory status and varied
24
dently before the anemia was corrected. However, a second prospec- from 22 to 34 percent in the low group to 30 to 46 percent in the high
tive study found no differences in postoperative functional mobility group. In each age group the transfusion threshold levels decreased with
or length of stay when comparing patients maintained on restrictive improving clinical status, as indicated by the level of respiratory support
25
(8 g/dL) or liberal (10 g/dL) transfusion strategies. However, the required. In either arm of the study, additional RBC transfusions could
liberal transfusion group had few cardiovascular complications and be given at the discretion of the attending neonatologist based on a set of
lower mortality when compared to the restrictive group. The authors predetermined circumstances. Infants in the restrictive arm of the study
concluded that a liberal transfusion strategy does not increase ambula- were more likely to have intraparenchymal brain hemorrhage or periven-
tion scores but that a restrictive strategy should be treated with caution tricular leukomalacia and also had more frequent episodes of mild and
in elderly high-risk hip fracture patients. severe apnea. The liberal arm received more RBC transfusions; however,
The population in the FOCUS trial was elderly, high-risk car- donor exposure was similar in both groups. The authors concluded that a
diovascular patients; the finding of an 8 g/dL Hgb threshold for RBC restrictive transfusion practice may be harmful to preterm infants.
transfusions may not be generalizable to the remaining lower-risk The largest trial of transfusion practice in preterm infants was the
32
orthopedic patient population. However, until adequately powered Premature Infants in Need of Transfusion (PINT) study. This random-
studies are conducted in these populations, applying the 8 g/dL trigger ized trial asked whether extremely-low-birth-weight infants transfused
is the safest approach for lower risk patients. While a Hgb of 8 g/dL is at different Hgb thresholds had different rates of survival or morbidity
safe for orthopedic patients, the quality-of-life studies indicate that a at discharge. A total of 451 infants, each weighing less than 1000 g at
higher Hgb allows for faster recovery. birth, were randomized into a low or high Hgb threshold group. The
thresholds ranged from 6.8 g/dL to 11.5 g/dL in the low group and 7.7 g/dL
RED BLOOD CELL TRANSFUSIONS to 13.5 g/dL in the high group. The actual threshold was determined
by a combination of age and presence or absence of respiratory sup-
FOR NEUROLOGICALLY IMPAIRED PATIENTS port. There was no statistically significant difference between the two
No large scale, prospective randomized trial has been done regard- groups in terms of death before home discharge or survival with severe
ing the safety and efficacy of transfusion practice in neurocritically ill morbidity. In addition, fewer infants received one or more transfusions
patients. The lack of large studies led to a systematic review of six studies in the low threshold group. The authors concluded that maintaining
that had a combined total of 537 patients. The Hgb triggers in these extremely-low-birth-weight infants at a higher Hgb threshold conferred
26
studies ranged from 7 to 10 g/dL in restrictive groups, to 9.3 to 11.5 g/dL no benefit.
in higher Hgb groups. While some studies reported shorter lengths of A Cochrane review of transfusion in neonates concluded that
stay in the lower Hgb groups, the systematic review found insufficient a restrictive approach resulted in a modest reduction in exposure to
evidence to guide transfusion practice in neurocritically ill patients. transfusion, but did not appear to have a significant impact on death or
major morbidities (Table 138–5). 33
RED BLOOD CELL TRANSFUSIONS
FOR PEDIATRIC PATIENTS HEMOGLOBINOPATHIES
Clinical trials of transfusion triggers for pediatric patients fall into two
basic categories: general studies of critically ill pediatric patients and SICKLE CELL DISEASE
studies focused on high-risk neonates. The Transfusion Strategies for Transfusion therapy is indicated for sickle cell patients suffering from
Patients in Pediatric Intensive Care Units (TRIPICU) trial and its affil- stroke, acute chest syndrome, acute exacerbations of anemia, and
iated subanalyses represent the major data set covering the pediatric other complications. Regular transfusions also significantly reduce

Kaushansky_chapter 138_p2365-2380.indd 2371 9/18/15 11:13 AM