Base administration or fluid bolus for preventing morbidity and mortality in preterm infants with metabolic acidosis

Neonatal Metabolic Acidosis in the Neonatal Intensive Care Unit: What Are the Genetic Causes?

Neonatal metabolic acidosis (NMA) is a common problem, particularly in critically ill patients in neonatal intensive care units (NICUs). Complex etiologies and atypical clinical signs make diagnosis difficult; thus, it is crucial to investigate the underlying causes of NMA rapidly and provide disorder-specific therapies. Our study aims to provide an overview of the genetic causes of NMA in patients from NICUs. We performed next-generation sequencing (NGS) on neonates with NMA from January 2016 to December 2019. Clinical features, genetic diagnoses, and their effects on clinical interventions were collected for analysis. In the 354 enrolled patients, 131 (37%) received genetic diagnoses; 95 (72.5%) of them were autosomal recessively inherited diseases. Two hundred and fifteen variants spanning 57 genes were classified as pathogenic (P) or likely pathogenic (LP) in 131 patients. The leading cause was metabolic disorders due to 35 genes found in 89 patients (68%). The other 42 NMA patients (32%) with 22 genes had malformations and renal, neuromuscular, and immune-hematological disorders. Seven genes (MMUT, MMACHC, CHD7, NPHS1, OTC, IVD, and PHOX2B) were noted in more than four patients, accounting for 48.9% (64/131) of the identified P/LP variants. Forty-six diagnosed patients with uncorrected NMA died or gave up. In conclusion, 37% of neonates with metabolic acidosis had genetic disorders. Next-generation sequencing should be considered when investigating the etiology of NMA in NICUs. Based on early molecular diagnoses, valuable treatment options can be provided for some genetic diseases to achieve better outcomes.

Effects of sodium bicarbonate correction of metabolic acidosis on regional tissue oxygenation in very low birth weight neonates

OBJECTIVE

To determine the effects of sodium bicarbonate (NaHCO3) correction of metabolic acidosis on cardiopulmonary, laboratory, and cerebral, renal and splanchnic regional oxygen saturation (rSO2) and fractional tissue oxygen extraction (FTOE) in extremely premature neonates during the first postnatal week.

STUDY DESIGN

Observational cohort data were collected from 500 to 1250 g neonates who received NaHCO3 'half' corrections (0.3 * Weight (kg) * Base Deficit (mmol l(-1))) for presumed renal losses.

RESULT

Twelve subjects with normal blood pressure and heart rate received 17 NaHCO3 corrections. Mean (±s.d.) gestational age was 27±2 week and birth weight was 912±157 g. NaHCO3 corrections provided a mean (±s.d.) 4.5±1.0 ml kg(-1) fluid bolus, shifted mean (±s.d.) base deficit from 7.6±1.8 to 3.4±2.1 mmol l(-1) (P<0.05), and increased median (±s.d.) pH from 7.23±0.06 to 7.31±0.05 (P<0.05). No significant changes in blood pressure, pulse oximetry, PCO2, lactate, sodium, blood urea nitrogen, creatinine or hematocrit were observed. Cerebral, renal and splanchnic rSO2 (74%, 66% and 44%, respectively, at baseline) and FTOE (0.21, 0.29 and 0.52, respectively, at baseline) were unchanged following NaHCO3 correction.

CONCLUSION

NaHCO3 infusions decreased base deficits and increased pH though produced no discernible effects or benefits on cardiopulmonary parameters including rSO2 and FTOE. These findings warrant further prospective evaluation in larger populations with more significant metabolic acidosis to determine the utility of tissue oxygenation monitoring in differentiating metabolic acidosis due to oxygen delivery/consumption imbalance versus renal bicarbonate losses.

Hemodynamic and metabolic correlates of perinatal white matter injury severity

Background and Purpose

Although the spectrum of perinatal white matter injury (WMI) in preterm infants is shifting from cystic encephalomalacia to milder forms of WMI, the factors that contribute to this changing spectrum are unclear. We hypothesized that the variability in WMI quantified by immunohistochemical markers of inflammation could be correlated with the severity of impaired blood oxygen, glucose and lactate.

Methods

We employed a preterm fetal sheep model of in utero moderate hypoxemia and global severe but not complete cerebral ischemia that reproduces the spectrum of human WMI.

Since there is small but measurable residual brain blood flow during occlusion, we sought to determine if the metabolic state of the residual arterial blood was associated with severity of WMI. Near the conclusion of hypoxia-ischemia, we recorded cephalic arterial blood pressure, blood oxygen, glucose and lactate levels. To define the spectrum of WMI, an ordinal WMI rating scale was compared against an unbiased quantitative image analysis protocol that provided continuous histo-pathological outcome measures for astrogliosis and microgliosis derived from the entire white matter.

Results

A spectrum of WMI was observed that ranged from diffuse non-necrotic lesions to more severe injury that comprised discrete foci of microscopic or macroscopic necrosis. Residual arterial pressure, oxygen content and blood glucose displayed a significant inverse association with WMI and lactate concentrations were directly related. Elevated glucose levels were the most significantly associated with less severe WMI.

Conclusions

Our results suggest that under conditions of hypoxemia and severe cephalic hypotension, WMI severity measured using unbiased immunohistochemical measurements correlated with several physiologic parameters, including glucose, which may be a useful marker of fetal response to hypoxia or provide protection against energy failure and more severe WMI.

The use of chloride-sodium ratio in the evaluation of metabolic acidosis in critically ill neonates

Acid-base disturbances have been usually evaluated with the traditional Henderson-Hasselbach method and Stewart's physiochemical approach by quantifying anions of tissue acids (TA). It is hypothesized that an increase in tissue acids during metabolic acidosis would cause a compensatory decrease in the plasma chloride (Cl) relative to sodium (Cl-Na ratio) in order to preserve electroneutral balance. Therefore, we aimed to investigate the use of Cl-Na ratio as a bedside tool to evaluate the identifying raised TA in neonates as an alternative to complex calculations of Stewart's physiochemical approach. This retrospective study was conducted between January 2008 and December 2009. Infants were included in the study when blood gas analysis reveals a metabolic acidosis; pH <7.25 and sHCO(3) concentration was <22 mEq/L. The Cl-Na ratio, sodium-chloride difference (Diff(NaCl)), anion gap (AG), albumin-corrected AG (AG(corr)), strong ion difference (SID), unmeasured anions (UMA), and TA were calculated at each episode of metabolic acidosis. A total of 105 metabolic acidosis episodes occurred in 59 infants during follow-up. Hypochloremic metabolic acidosis occurred in 17 (16%) of samples, and all had increased TA. The dominant component of TA was UMA rather than lactate. There was a negative correlation between the Cl-Na ratio and SID, AG(corr), UMA, and TA. Also, there was a positive correlation between Diff(NaCl) and SID, AG(corr), UMA, and TA. Base deficit and actual bicarbonate performed poorly in identifying the TA. In conclusion, our study suggested that Diff(NaCl) and Cl-Na ratio are simple and fast, and may be an alternative method to complex Stewart's physiochemical approach in identifying raised UMA and TA in critically ill neonates.

Sodium bicarbonate administration and outcome in preterm infants

The short-term outcomes of sodium bicarbonate therapy in preterm infants were investigated by retrospective analysis of 165 of 984 infants who received sodium bicarbonate. The infants treated with sodium bicarbonate were more immature and had greater severity of illness and more adverse outcomes. Sodium bicarbonate therapy did not improve the blood pH.

Sodium bicarbonate: basically useless therapy

Common clinical practices often are unsupported by experimental evidence. One example is the administration of sodium bicarbonate to neonates. Despite a long history of widespread use, objective evidence that administration of sodium bicarbonate improves outcomes for patients in cardiopulmonary arrest or with metabolic acidosis is lacking. Indeed, there is evidence that this therapy is detrimental. This review examines the history of sodium bicarbonate use in neonatology and the evidence that refutes the clinical practice of administering sodium bicarbonate during cardiopulmonary resuscitation or to treat metabolic acidosis in the NICU.

Newborn resuscitation: defining best practice for low-income settings

Current resuscitation practices are often poor in low-income settings. The purpose of this review was to summarise recent evidence, relevant to developing countries, on best practice in the provision of newborn resuscitation. Potential studies for inclusion were identified using structured searches of MEDLINE via PubMed. Two reviewers independently evaluated retrieved studies for inclusion. The methodological quality of the selected articles was assessed using the Oxford Centre for Evidence-Based Medicine (CEBM) levels of evidence, whilst the Scottish Intercollegiate Guidelines Network (SIGN) grading system was used for subsequent recommendations. Based on available evidence, where there is meconium-stained liquor, routine perineal suction of all babies and endotracheal suction of active babies do not prevent meconium aspiration syndrome and have potential risks. Adequate ventilation is possible with a bag-valve-mask device and room air is just as efficient as oxygen for initial resuscitation. This review supports the view that effective resuscitation is possible with basic equipment and minimal skills. Thus, where resources are limited, it should be possible to improve neonatal outcomes through promotion of the effective use of a bag-valve-mask alone, without access to more sophisticated and expensive technologies. Basic, effective resuscitation should therefore be available at all health facilities and potentially in the community.

Base administration or fluid bolus for preventing morbidity and mortality in preterm infants with metabolic acidosis

BACKGROUND

Metabolic acidosis in the early newborn period is associated with adverse outcomes in preterm infants. The most commonly used strategies to correct metabolic acidosis are intravascular infusion of base, for example sodium bicarbonate, and intravascular infusion of a fluid bolus, usually a crystalloid or colloid solution.

OBJECTIVES

To evaluate the available evidence from randomised controlled trials that either infusion of base, or of a fluid bolus, reduces mortality and adverse neurodevelopmental outcomes in preterm infants with metabolic acidosis.

SEARCH STRATEGY

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005), MEDLINE (1966 - January 2005), EMBASE (1980 - January 2005), CINAHL (1982 - January 2005).

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that evaluated the following treatments for preterm infants with metabolic acidosis:1. Infusion of base versus no treatment.2. Infusion of fluid bolus versus no treatment.3. Infusion of base versus fluid bolus.

DATA COLLECTION AND ANALYSIS

We extracted the data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two authors, and synthesis of data using relative risk and risk difference.

MAIN RESULTS

We found two small randomised controlled trails that fulfilled the eligibility criteria (Corbet 1977; Dixon 1999). Corbet 1977 compared treating infants with sodium bicarbonate infusion (N = 30) versus no treatment (N = 32) and did not find evidence of an effect on mortality [Relative risk 1.39 (95% confidence interval 0.72 to 2.67), risk difference 0.12 (95% confidence interval -0.12 to 0.36)], or in the incidence of intra/peri-ventricular haemorrhage [Relative risk 1.24 (95% confidence interval 0.47 to 3.28), risk difference 0.05 (95% confidence interval -0.16 to 0.25)]. Dixon 1999 compared treatment with sodium bicarbonate (N = 16) versus fluid bolus (N = 20). The primary outcome assessed was arterial blood pH/base excess two hours after the intervention. Other clinical outcomes were not reported. Neither trial assessed longer term neurodevelopmental outcomes.

AUTHORS' CONCLUSIONS

There is insufficient evidence from randomised controlled trials to determine whether infusion of base or fluid bolus reduces morbidity and mortality in preterm infants with metabolic acidosis. Further large randomised trials are needed.