Uses and abuses of sodium bicarbonate in the neonatal intensive care unit

ABCs of base therapy in neonatology: role of acetate, bicarbonate, citrate and lactate

Metabolic acidosis is common in preterm and term newborn infants and may be attributed to a variety of etiologies, potentially requiring base therapy such as acetate or bicarbonate. However, concerns exist regarding potential harm of sodium bicarbonate due to intracellular acidosis, fluctuations in cerebral blood flow, and osmolar load with rapid infusions, with no improvement in survival when used during resuscitation. Alternative approaches to correct metabolic acidosis include the addition of acetate in parenteral nutrition, intravenous lactated Ringer's (LR) solution, and use of oral citrate. Current guidelines focus on addressing the underlying cause of acidosis, reserving the use of sodium bicarbonate (NaHCO3) for severe cases requiring acute correction, LR instead of saline for volume boluses and using acetate or citrate for slow correction to stabilize acid-base status. Further research is necessary to better understand the efficacy and safety of acetate, NaHCO3, and other base sources in treating metabolic acidosis in neonates.

The practices of intravenous sodium bicarbonate therapy in neonatal intensive care units: A multi-country survey

A common occurrence in the neonatal intensive care unit (NICU) is metabolic acidosis. Sodium bicarbonate (SB) has been widely used, but there is insufficient evidence on how SB affects neonates in NICUs with metabolic acidosis. The worsening of intracellular acidosis, the impairment of myocardial function, fluctuations in cerebral blood flow, and intracranial hemorrhage are some of the unfavorable effects of SB treatment in neonates that have been documented in the literature. This study aimed to explore neonatologists' practices for using intravenous SB (ISB) in NICUs. A multi-country survey was carried out in 2022 using an online questionnaire sent to neonatologists in various countries in order to gather information about the use of ISB in NICUs. A previously validated questionnaire was adapted and used in this study. The response rate was 67%. The findings show that 91.2% of neonatologists were using SB to correct metabolic acidosis in the NICU; 71.4% did not have written guidelines for using sodium bicarbonate. The majority of them (78.9%) reported that dosage is included in their guidelines for the use of ISB. The findings of this study emphasize the critical importance of providing guidelines in using ISB for managing metabolic acidosis in NICU to standardize procedures and reduce the use of potentially unsuitable and unsafe treatments, as it has been shown that 71.4% of neonatologists worldwide use sodium bicarbonate without guidelines.

Use of intravenous sodium bicarbonate in neonatal intensive care units in Italy: a nationwide survey

Background

Metabolic Acidosis (MA) is a disturbance of the acid-base balance that can occur in preterm and critically ill term neonates due to different etiologies. Intravenous sodium bicarbonate (SB) has been traditionally used to correct such unbalance, despite the lack of evidence about its safety and efficacy. In literature, reported undesirable effects of treatment with SB in neonates include worsening of intracellular acidosis, impairment of myocardial function, cerebral blood flow fluctuations and intracranial hemorrhage. A national survey was conducted by the Neonatal Pharmacotherapy Study Group of the Italian Society of Neonatology with the aim to assess and describe attitudes and practices concerning the use of SB, particularly for the treatment of MA in Italian NICUs.

Methods

A questionnaire regarding treatment of MA and SB prescription habits was sent to the directors of 120 Italian NICUs from June 2017 to March 2018.

Results

The survey response rate was 97.5% (117/120 centers). Findings showed that in 55% of the surveyed NICUs (64/117 units) it is common practice to correct MA with intravenous SB. On the other hand, the remaining 45% of the units try to solve the metabolic disturbances adopting different approaches (improving perfusion, adjusting ventilation parameters or increasing blood volume). Moreover, to prevent the occurrence of MA, 37.6% of the NICUs (44/117) include buffer salts (lactate, acetate or both) in parenteral nutrition prescriptions. SB is also used as a treatment for other conditions, mainly pathologies with bicarbonate loss and tubular acidosis (respectively in 53.8 and 32.5% of the NICUs).

Conclusion

This survey showed how SB is a commonly used treatment for MA in more than half of Italian NICUs, with indications and prescription criteria that significantly vary across centers. Based on current knowledge, it is reasonable to suggest that the management of neonatal MA should be firstly directed to identify the underlying disorders. Thus, the use of SB should be reserved only for selected cases, also considering the severity of SB adverse effects and the lack of evidence about its efficacy. Guidance for the management of MA is required to harmonize practices and reduce the use of potentially inappropriate and unsafe treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-021-00955-3.

Bicarbonate Therapy for Critically Ill Patients with Metabolic Acidosis: A Systematic Review

The management of acid-base disorders always calls for precise diagnosis and treatment of the underlying disease. Sometimes additional means are necessary to combat systemic acidity itself. In this systematic review, we discuss the concept and some specific aspects of bicarbonate therapy for critically ill patients with metabolic acidosis (i.e., patients with blood pH < 7.35). We conducted a systematic literature review of three online databases (PubMed, Google Scholar, and Cochrane) in November 2018 to validate usage of bicarbonate therapy for critically ill patients with metabolic acidosis. Twelve trials and case series were included in the final analysis, from which we assessed population, intervention, comparison, and outcome data. The current literature suggests limited benefit from bicarbonate therapy for patients with severe metabolic acidosis (pH < 7.1 and bicarbonate < 6 mEq/L). However, bicarbonate therapy does yield improvement in survival for patients with accompanying acute kidney injury.

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.

Metabolic acidosis in the first 14 days of life in infants of gestation less than 26 weeks

Extremely immature newborns develop a self-limiting normal anion gap metabolic acidosis in early life. This study examined the natural history of this acidosis in a population of infants of gestation less than 26 weeks in the first 14 days of life. The acidosis was maximal on day 4 with a mean base deficit of 10.6 mmol/l and had resolved in 90 % of infants by day 11. Dopamine usage was the only independent predictor of the acidosis. Its use was associated with a greater degree of acidosis.

CONCLUSION

Extremely preterm infants experience a self-limiting normal anion gap metabolic acidosis in the first 2 weeks of life which is consistent with renal tubular immaturity.

Sodium bicarbonate therapy in patients with metabolic acidosis

Metabolic acidosis occurs when a relative accumulation of plasma anions in excess of cations reduces plasma pH. Replacement of sodium bicarbonate to patients with sodium bicarbonate loss due to diarrhea or renal proximal tubular acidosis is useful, but there is no definite evidence that sodium bicarbonate administration to patients with acute metabolic acidosis, including diabetic ketoacidosis, lactic acidosis, septic shock, intraoperative metabolic acidosis, or cardiac arrest, is beneficial regarding clinical outcomes or mortality rate. Patients with advanced chronic kidney disease usually show metabolic acidosis due to increased unmeasured anions and hyperchloremia. It has been suggested that metabolic acidosis might have a negative impact on progression of kidney dysfunction and that sodium bicarbonate administration might attenuate this effect, but further evaluation is required to validate such a renoprotective strategy. Sodium bicarbonate is the predominant buffer used in dialysis fluids and patients on maintenance dialysis are subjected to a load of sodium bicarbonate during the sessions, suffering a transient metabolic alkalosis of variable severity. Side effects associated with sodium bicarbonate therapy include hypercapnia, hypokalemia, ionized hypocalcemia, and QTc interval prolongation. The potential impact of regular sodium bicarbonate therapy on worsening vascular calcifications in patients with chronic kidney disease has been insufficiently investigated.

While waiting: early recognition and initial management of neonatal hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) occurring during the perinatal period is one of the primary causes of severe, long-term neurological deficits in children. Initial systemic supportive therapy remains a critical aspect of HIE management. In addition to support therapy, the widespread use of hypothermia has demonstrated a reduction in death and neurodevelopmental disability in infants with moderate to severe HIE. Neonates with HIE born outside of tertiary care centers must be rapidly identified as hypothermia candidates and have emergent transport arranged. While waiting for the transport team to arrive, these neonates often require intensive stabilization, including meticulous temperature management. This article examines the need for HIE outreach teaching programs, assists in the identification of a neonate for hypothermia therapy, and supplies evidence-based recommendations for the initial stabilization and care of neonates delivered at nontertiary care facilities. The guidelines and materials supplied represent the outreach model used by our regional hypothermia center and disseminated to the surrounding referral hospitals.

Infusing sodium bicarbonate suppresses hydrogen peroxide accumulation and superoxide dismutase activity in hypoxic-reoxygenated newborn piglets

Background

The effectiveness of sodium bicarbonate (SB) has recently been questioned although it is often used to correct metabolic acidosis of neonates. The aim of the present study was to examine its effect on hemodynamic changes and hydrogen peroxide (H₂O₂) generation in the resuscitation of hypoxic newborn animals with severe acidosis.

Methods

Newborn piglets were block-randomized into a sham-operated control group without hypoxia (n = 6) and two hypoxia-reoxygenation groups (2 h normocapnic alveolar hypoxia followed by 4 h room-air reoxygenation, n = 8/group). At 10 min after reoxygenation, piglets were given either i.v. SB (2 mEq/kg), or saline (hypoxia-reoxygenation controls) in a blinded, randomized fashion. Hemodynamic data and blood gas were collected at specific time points and cerebral cortical H₂O₂ production was continuously monitored throughout experimental period. Plasma superoxide dismutase and catalase and brain tissue glutathione, superoxide dismutase, catalase, nitrotyrosine and lactate levels were assayed.

Results

Two hours of normocapnic alveolar hypoxia caused cardiogenic shock with metabolic acidosis (pH: 6.99±0.07, HCO₃⁻: 8.5±1.6 mmol/L). Upon resuscitation, systemic hemodynamics immediately recovered and then gradually deteriorated with normalization of acid-base imbalance over 4 h of reoxygenation. SB administration significantly enhanced the recovery of both pH and HCO₃₋ recovery within the first hour of reoxygenation but did not cause any significant effect in the acid-base at 4 h of reoxygenation and the temporal hemodynamic changes. SB administration significantly suppressed the increase in H₂O₂ accumulation in the brain with inhibition of superoxide dismutase, but not catalase, activity during hypoxia-reoxygenation as compared to those of saline-treated controls.

Conclusions

Despite enhancing the normalization of acid-base imbalance, SB administration during resuscitation did not provide any beneficial effects on hemodynamic recovery in asphyxiated newborn piglets. SB treatment also reduced the H₂O₂ accumulation in the cerebral cortex without significant effects on oxidative stress markers presumably by suppressing superoxide dismutase but not catalase activity.

Prescribing in maternity care in Russia: The legacy of Soviet medicine

Remarkably, there has been very little detailed research on clinical practice in Russia and its neighbours in what was the USSR, even though it is known that the USSR was isolated from many international developments, in particular evidence-based medicine. In this study we examine obstetric practice, an area of practice where there is an extensive body of evidence on the appropriateness of many interventions. The study is undertaken in Tula, a region 200 km south of Moscow. Building on earlier detailed analyses of data from the facilities in the region, it reports a series of structured interviews with 52 obstetricians from all 19 facilities in the region, designed to identify patterns of prescribing, supplemented by 36 more detailed re-interviews to explore reasons for the differing practices. The study demonstrates a widespread divergence from internationally accepted practice. Maternity care is extremely medicalised but many non-evidence based medicines are used. Some are heavily marketed by large pharmaceutical companies, some were widely used during the Soviet period but never evaluated, and a few are not known to be used anywhere else in the world. For several conditions, the most widely used drugs are clearly inferior to alternative products and some are used for indications quite different from those in other countries. This study contributes to the growing evidence that much of the care provided in Russian maternity units is ineffective or potentially dangerous but also begins to offer some explanations for why this is, including a lack of access to information and a lack of awareness of the concept of evidence-based practice.

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.

Effect of bicarbonate on retinal vasculature and acidosis-induced retinopathy in the neonatal rat

BACKGROUND

Systemic acidosis induces preretinal neovascularization (NV) analogous to retinopathy of prematurity (ROP) in the neonatal rat. Sodium bicarbonate is used in human neonates to treat acidosis. The effects of alkali administration on the developing retinal vasculature and on acidosis-induced retinopathy (AIR) are unknown. We investigated the effect of sodium bicarbonate gavage on the retinal vasculature of normal and acidotic neonatal rats to determine (1) whether bicarbonate treatment is associated with preretinal NV and (2) whether AIR can be prevented with systemic bicarbonate treatment.

METHODS

The extent of acidosis and alkalosis were initially determined from carotid arterial blood samples. In the bicarbonate-alone study, newborn rats were randomized into litters of 25 and received bicarbonate doses of 15 mmol/kg twice daily and 20 mmol/kg once daily from days 2 to 7. Control animals received saline gavage. In the AIR treatment study, acidosis was induced in neonatal rats by intraperitoneal injection of acetazolamide 200 mg/kg from days 2 to 7. Acetazolamide-treated rats received either additional bicarbonate gavage or no additional treatment. Eyes were enucleated on day 13, and the retinal vasculature was assessed for NV using ADPase staining techniques and light microscopy.

RESULTS

Systemic alkalosis (peak pH 7.55+/-0.02; mean +/- SD) was confirmed with bicarbonate gavage, and partial reversal of acidosis was confirmed when acetazolamide-treated rats received bicarbonate. Surviving rats receiving bicarbonate 15 mmol/kg twice daily (28% survival) and 20 mmol/kg bicarbonate once daily (45% survival) had an incidence of preretinal NV of 9% and 8%, respectively. No NV was seen in saline-control rats. In the acetazolamide-treated rats, the incidence of preretinal NV in surviving rats was numerically lower in bicarbonate-treated rats than acetazolamide-only controls (8% versus 24%, p=0.065) but with only 19% survival in the bicarbonate-treated rats.

CONCLUSIONS

In the neonatal rat, alkalosis induced by bicarbonate gavage is associated with a low incidence of mild, preretinal NV similar to ROP. Although treating acidotic rats with bicarbonate may reduce the incidence of preretinal NV, treatment was associated with an unacceptable mortality rate.

Effect of a single dose of sodium bicarbonate given during neonatal resuscitation at birth on the acid-base status on first day of life

OBJECTIVE

To study the effect of a single dose of sodium bicarbonate given during neonatal resuscitation at birth on the acid-base status on the first day of life.

SETTING

Tertiary care Level III NICU.

STUDY DESIGN

A total of 55 consecutively born asphyxiated neonates continuing to receive positive pressure ventilation at 5 minutes of life were randomized to receive either 4 ml/kg (1.8 meq/kg) of sodium bicarbonate or 5% dextrose.

RESULTS

The mean pH, base deficit and PaCO(2) were similar between the Base group and the Control group for the first 24 hours of life. The number of babies with persistent metabolic acidosis at 1, 6, 12 and 24 hours were comparable between the two groups.

CONCLUSION

Sodium bicarbonate given during neonatal resuscitation did not change the acid-base status in the first 24 hours of life.