Randomised controlled trial: comparison of colloid or crystalloid for partial exchange transfusion for treatment of neonatal polycythaemia

Neonatal polycythaemia: critical review and a consensus statement of the Israeli Neonatology Association

The aim of this paper is to critically review neonatal polycythaemia (NP) literature, in terms of definition, diagnosis and management. We reviewed all Medline articles on NP up to December 2009. (i) The textbook definition of NP [venous haematocrit (HCT) > 65%] is empirical and not based on statistical definition, symptoms or complications. (ii) Measurement of viscosity is not better than HCT in predicting complications. (iii) Normovolaemic NP because of increased erythropoiesis may be different from hypervolaemic polycythaemia because of excessive foetal transfusion. (iv) Coexisting hypoglycaemia may worsen long-term outcome. (v) Four clinical trials (CTs) studied partial exchange transfusion (PET) on outcomes. In all trials, PET was performed after 6 h of life. There is no evidence that PET improves neurodevelopmental outcome of asymptomatic NP, and it might increase the risk of necrotizing enterocolitis. These CTs have inherent design flaws: (a) CNS 'damage' may occur before PET. (b) Confounding variables that may affect outcome have not been studied. (vi) If PET is performed, normal saline is the best alternative. (vii) The long-term effect of PET on symptomatic infants has not been studied.

CONCLUSION

Current definition and management of NP are little evidence based, thus the need for a consensus based on expert opinion.

Neonatal fluid management

Perioperative fluid management in paediatrics has been the subject of many controversies in recent years, but fluid management in the neonatal period has not been considered in most reviews and guidelines. The literature regarding neonatal fluid management mainly appears in the paediatric textbooks and few recent data are available, except for resuscitation and fluid loading during shock and major surgery. In the context of anaesthesia, many neonates requiring surgery within the first month of life have organ malformation and/or dysfunction. This article aims at reviewing basic physiological considerations important for neonatal fluid management and mainly focusses on fluid maintenance and replacement during surgery.

Partial exchange transfusion to prevent neurodevelopmental disability in infants with polycythemia

BACKGROUND

Hyperviscosity of blood results in increased resistance to blood flow and decreased oxygen delivery. In the neonate, hyperviscosity can cause abnormalities of central nervous system function, hypoglycemia, decreased renal function, cardiorespiratory distress, and coagulation disorders. Hyperviscosity has been reported to be associated with long-term motor and cognitive neurodevelopmental disorders. Blood viscosity exponentially increases when an infant has polycythemia (hematocrit >/= 65%). Partial exchange transfusion (PET) is traditionally used as the method to lower the hematocrit and treat hyperviscosity.

OBJECTIVES

To evaluate the effect of PET on mortality and neurodevelopmental outcome in infants with neonatal polycythemia.

SEARCH STRATEGY

Electronic databases searched included: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (1966 to October 2009), EMBASE (1980 to October 2009) and CINAHL (1982 to October 2009).

SELECTION CRITERIA

Randomized controlled clinical trials or quasi-randomized trials comparing partial exchange transfusion to control (non-treatment) in infants with neonatal polycythemia

DATA COLLECTION AND ANALYSIS

Data collection and analysis was performed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

One study (Kumar 2004) reported no demonstrable effect on the risk of neonatal mortality (RR 5.23, 95% CI 0.66, 41.26).Four studies reported on neurodevelopmental assessment at 18 months or older. The completeness of follow-up differed widely between the studies. Overall, no difference was seen in developmental delay when all trials are analysed based on available cases (typical RR 1.45, 95% CI 0.83 to 2.54) and when only the randomized controlled trials are analysed (typical RR 1.35, 95% CI 0.68 to 2.69). A best case/worst case analysis of developmental delay is consistent with large benefit or harm from PET.Two studies reported on necrotizing enterocolitis (Van der Elst 1980; Black 1985). An increase in the risk of NEC was noted in infants receiving PET (typical RR 11.18, 95% CI 1.49, 83.64; typical RD 0.14, 95% CI 0.05, 0.22). No differences in short-term complications including hypoglycemia (two studies) and thrombocytopenia (one study) were noted.

AUTHORS' CONCLUSIONS

There are no proven clinically significant short or long-term benefits of PET in polycythemic newborn infants who are clinically well or who have minor symptoms related to hyperviscosity. PET may lead to an increase in the risk of NEC. The data regarding developmental follow-up is extremely imprecise due to the large number of surviving infants who were not assessed and, therefore, the true risks and benefits of PET are unclear.

Neonatal polycythemia and hyperviscosity

Neonatal polycythemia and hyperviscosity are defined as a hematocrit > or =65% and a viscosity value >2 standard deviations greater than the norm. Although polycythemia can reflect normal fetal adaptation, it has been thought to be responsible for abnormalities in the neonate. Polycythemia and hyperviscosity are associated with blood-flow changes in some organs, which alter their function. Partial exchange transfusion (PET) has been used to treat both symptomatic and asymptomatic patients. At present, no data support the use of PET in asymptomatic infants; the potential benefit in symptomatic infants depends on the symptoms. Studies of long-term neurodevelopmental status do not show any clear long-term benefits for PET. Crystalloids are as effective as colloids in PET and have the advantage of being cheaper and more readily available; also, they do not confer any risk of infection or anaphylaxis.

Systematic review of the optimal fluid for dilutional exchange transfusion in neonatal polycythaemia

OBJECTIVES

Several studies have shown the efficacy of dilutional exchange transfusion (DET) in reducing haematocrit (Ht) and relieving clinical symptoms in neonatal polycythaemia. We conducted a systematic review to determine the efficacy of crystalloid versus colloid solutions used in DET in an effort to identify the best solution to replace red blood cells.

METHODS

The Cochrane Library, MEDLINE, and EMBASE were searched for relevant randomised controlled trials. Quality assessment and data analysis were performed using the methods and software of the Cochrane Collaboration. Relative risk (RR) and weighted mean difference (WMD) were calculated as measures of effect for categorical and continuous outcome data, respectively. Ninety five percent confidence intervals (95% CI) were calculated and a fixed effect model was used for meta-analysis.

RESULTS

Six studies with a total of 235 newborns matched our inclusion criteria. When comparing crystalloid and colloid replacement solutions for DET, there was a clinically unimportant difference in Ht at 2-6 h and at 24 h in favour of colloidal solutions (WMD 2.29% (95% CI 1.28 to 3.31) and 1.74% (95% CI 0.80 to 2.68), respectively). This difference in post DET Ht was more evident when normal saline was compared to plasma but absent when normal saline was compared to 5% albumin.

CONCLUSION

There is little difference in effectiveness between plasma, 5% albumin, and crystalloid solutions. Since normal saline is cheap, readily available, and does not carry the potential risk of transfusion associated infection, normal saline is the optimal dilutional fluid for exchange transfusion in polycythaemic neonates.

Crystalloid or colloid for partial exchange transfusion in neonatal polycythemia: a systematic review and meta-analysis

AIMS

To determine whether crystalloid solutions are as effective as colloid solutions when a partial exchange transfusion is performed in newborns with polycythemia.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Register of the Cochrane Library (1966-2004). Keywords used were: polycythemia, partial exchange transfusion, hyperviscosity, and limited to newborn. Randomized studies in newborns with polycythemia were selected for evaluation. Outcomes examined were: long-term neurodevelopment; short-term physiological effects; improvement in clinical symptoms; reduction in haematocrit at 4-6 h; haematocrit at 24 h; and frequency of serious complications.

RESULTS

Four randomized controlled clinical trials, including 200 patients in total, with evaluable data, which satisfied our criteria, were found. There were no data on long-term outcomes. There is no reported important difference in short-term physiologic effects. Use of crystalloid was as effective as colloid in both correction of haematological values and reduction of clinical symptoms following partial exchange transfusion.

CONCLUSION

Crystalloid solutions are as effective as colloid solutions for partial exchange transfusion. When crystalloid solutions are used for this purpose, there is no risk of transmission of blood-borne diseases, there is no risk of anaphylaxis, they are rapidly and easily available, and are less expensive. The use of crystalloid should become the standard for partial exchange transfusion.

Neonatal management of the growth-restricted infant

Close collaboration between obstetricians and neonatologists is essential for proper care of the growth-restricted fetus. A joint decision on the appropriate timing of delivery is made, based on the risk of fetal compromise compared with that of neonatal morbidity. A neonatal resuscitative team should be available at delivery. Gestational assessment, anthropological measurements and physical examination are necessary to confirm the diagnosis of intra-uterine growth retardation and establish the symmetric, asymmetric, combined or dysmorphic classification. Neonatal management requires special attention to a number of significant morbidities that growth-restricted infants are more prone to develop compared with normally grown infants, including asphyxia, meconium aspiration syndrome, respiratory distress syndrome, massive pulmonary haemorrhage, chronic lung disease, hypothermia, hypoglycaemia, hypocalcaemia, polycythaemia-hyperviscosity, intraventricular haemorrhage, sepsis, necrotizing enterocolitis, coagulation abnormalities, and congenital anatomical and genetic abnormalities. Intra-uterine growth retardation is associated with a higher stillbirth rate and infant mortality rate in preterm, term and post-term infants.

Neonatal polycythemia: is partial exchange transfusion justified?

In clinical practice, neonatal polycythemia has been used as a marker for neonatal hyperviscosity, implicated as a cause of long-term neurologic delay and damage in the growing child. Clinicians have focused on the newborn infant's hematocrit (Hct) level as the criterion for therapeutic intervention. Partial exchange transfusion is traditionally used as the method to lower the Hct and treat hyperviscosity; however, it is unclear whether this is an effective approach in preventing the long-term neurologic consequences. This article re-evaluates this clinical approach to the diagnosis and treatment of neonatal polycythemia and suggests that this controversial therapy needs re-evaluation.

The albumin controversy

There are relatively few studies of albumin use in neonates and children, with most showing no consistent benefit compared with the use of crystalloid solutions. Certainly, albumin treatment is not indicated for treatment of hypoalbuminemia alone. Studies also show that albumin is not indicated in neonates for the initial treatment of hypotension, respiratory distress, or partial exchange transfusions. In adults, albumin is not considered to be the initial therapy for hypovolemia, burn injury, or nutritional supplementation. Based on the evidence, albumin should be used rarely in the neonatal ICU. Albumin may be indicated in the treatment of hypovolemia only after crystalloid infusion has failed. In patients with acute hemorrhagic shock, albumin may be used with crystalloids when blood products are not available immediately. Inpatients with acute or continuing losses of albumin and normal capillary permeability and lymphatic function, such as during persistent thoracostomy tube or surgical site drainage, albumin supplementation will prevent the development of hypoalbuminemia, and possibly edema formation. This has not been studied systematically, however. In patients with hypoalbuminemia and increased capillary permeability, albumin supplementation often leads to greater albumin leakage across the capillary membrane, contributing to edema formation without improvement in outcome. As the disease process improves and capillary permeability normalizes, albumin supplementation may accelerate recovery, but long-term benefits of albumin treatment usually cannot be demonstrated. These patients will recover whether or not albumin is administered.

Differential diagnosis and management of polycythemia

One percent to 5% of all newborns in the United States are polycythemic.As the venous hematocrit rises above 65%, the thickness or viscosity of whole blood also increases, potentially compromising blood flow to a variety of organs. Fortunately, relatively few infants who have neonatal polycythemia or hyperviscosity develop complications attributable to their thick blood; however, controversy and the need for continued research envelop the issue of which infants are at risk and need to be treated. This article reviews the differential diagnosis, clinical presentation, and treatment of neonatal polycythemia.

Neonatal transfusion practice

Many previously widely accepted neonatal transfusion practices are changing as neonatologists become more aware of the risks to their patients of multiple blood product transfusions. Recent literature and research on neonatal transfusion practice are here reviewed, and practical guidelines and trigger thresholds for blood products commonly used in neonatal medicine are proposed.

Early volume expansion for prevention of morbidity and mortality in very preterm infants

BACKGROUND

Reduced perfusion of organs such as the brain, heart, kidneys and the gastrointestinal tract may lead to acute dysfunction and be associated with permanent injury. Various strategies have been used to provide cardiovascular support to preterm infants including inotropes, corticosteroids and volume expansion.

OBJECTIVES

In very preterm infants, does early volume expansion reduce morbidity and mortality. If volume expansion is effective, what type of volume expansion is most effective.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. See Review Group details for more information. This was supplemented by additional searches of the Oxford Database of Perinatal Trials, and updated search performed of the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library Issue 1, 2004), MEDLINE (1996-January 2004), EMBASE (1980-January 2004), previous reviews including cross references (all articles referenced), abstracts and conferences (Perinatal Society of Australia and New Zealand, and Pediatric Academic Societies and American Academy of Pediatrics meetings 1998-2003).

SELECTION CRITERIA

Randomised trials of early volume expansion with normal saline, fresh frozen plasma, albumin, plasma substitutes or blood compared to no treatment or another form of volume expansion in preterm infants < 32 weeks gestation or < 1500g were included. Volume expansion was defined as at least 10 mls/kg given in the first 72 hours of life.

DATA COLLECTION AND ANALYSIS

Standard methods of the Neonatal Review Group with use of relative risk (RR), risk difference (RD) and weighted mean difference (WMD). The fixed effects model using RevMan 4.1 was used for meta-analysis. Data from individual studies were only eligible for inclusion if a least 80% of infants were reported for that outcome.

MAIN RESULTS

Seven studies were included. Five studies, four with data for mortality, compared volume to no treatment. Most studies enrolled very preterm infants on the basis of gestation or birthweight. Two studies comparing different types of volume expansion enrolled very preterm infants with hypotension. No study enrolled infants on the basis of low blood flow. One study examined the effect of volume expansion on blood flow but in normotensive very preterm infants. Comparing volume and no treatment, 4 studies with a total of 940 very preterm infants reported no significant difference in mortality (RR 1.11, 95% CI 0.88, 1.40). The large NNNI 1996 study reported no significant difference in severe disability (RR 0.80, 95% CI 0.52, 1.23), cerebral palsy (RR 0.76, 95% CI 0.48, 1.20) and combined death or severe disability (RR 1.00, 95% CI 0.80, 1.24). Although one small study (Beverley 1985) reported reduced P/IVH with volume expansion, this was not supported by any other study. No significant difference was reported in grade 3-4 P/IVH and combined death or grade 3-4 P/IVH. One study (NNNI 1996) reported no significant difference in the incidence of hypotension. The finding of decreased necrotising enterocolitis and increased sepsis in infants who received fresh frozen plasma compared to a gelatin-based plasma substitute or no treatment in one study should be treated with caution. No significant differences in mortality or disability were found in this study. Comparing albumin and saline in hypotensive infants, one study (Lynch 2002) reported a significant increase in mean BP and reduced incidence of treatment failure (persistent hypotension). The other study (So 1997) and the meta-analysis of the two studies found no significant difference in treatment failure (RR 0.75, 95% CI 0.53, 1.06) or in any other clinical outcome.

REVIEWERS' CONCLUSIONS

There is no evidence from randomised trials to support the routine use of early volume expansion in very preterm infants without cardiovascular compromise. There is insufficient evidence to determine whether infants with cardiovascular compromise benefit from volume expansion. There is insufficient evidence to determine what type of volume expansion should be used in preterm infants (if at all) or for the use of early red cell transfusions. The significance of the finding of a significant increase in blood pressure in hypotensive preterm infants in one trial comparing albumin and saline is unclear, but the overall meta-analyses found no other significant clinical benefit in using albumin compared to saline.

Choosing a volume expander in critical care medicine

The debate concerning the choice of crystalloids or colloids for resuscitation of the critically ill child is still unsettled. Moreover, the use of albumin in critically ill patients has been increasingly questioned because of the lack of clear-cut advantages over crystalloids as well as the concern for cost and the very minor risk of infection. Despite several meta-analyses addressing these issues, there is no data that supports the use of albumin unequivocally in any specific disease states. The suggestion that the use of albumin increases mortality in critically ill patients is not supported by data. There may be niche areas such as hypoalbuminic states, cirrhosis and burns where albumin may have distinct benefits. Alternatively synthetic colloids may be useful, however, concerns about coagulation problems and organ dysfunction persists.

Polycythemia in the newborn

Neonatal polycythemia, a venous hematocrit >65%, occurs in 1% to 5% of the total newborn population. Polycythemia can result from an excess production of red blood cells (active form) or from an increase in fetal blood volume (passive form). Clinical manifestations of polycythemia are caused by an increase in whole blood viscosity with a subsequent decrease in blood flow to organ systems. However, little information exists in the nursing literature concerning neonatal polycythemia. This article addresses the two categories of polycythemia and their etiologies; the involved pathophysiology; clinical manifestations of affected organ systems; supportive and specific therapies that can be used to treat polycythemic infants; the prognosis for polycythemic infants; and the difficulty healthcare providers face in deciding whether to treat this disorder. In addition, a case of a symptomatic infant who was treated with a partial exchange transfusion is presented.