Low systemic blood flow and hyperkalemia in preterm infants

doi:10.1067/mpd.2001.115315

The Journal of Pediatrics

Volume 139, Issue 2, August 2001, Pages 227-232

https://doi.org/10.1067/mpd.2001.115315 Get rights and content

Abstract

Objective: Early low systemic blood flow is common in preterm infants. This study examines the relationship among low flow, renal function, and early changes in blood potassium (K⁺). Methods: Preterm infants (n = 119) born before 30 weeks’ gestational age underwent serial Doppler echocardiographic studies. Superior vena cava flow (SVC flow) was assessed as a measure of upper body systemic blood flow uncorrupted by systemic to pulmonary shunts. Serial whole blood K⁺ concentrations on each arterial blood gas sample and urinary output in the first 48 hours were recorded. Results: Most infants had a variable degree of rise in K⁺ during the first 24 hours of life. The mean rate of rise was 0.17 mmol/L/h, the mean peak K⁺ was 5.54 mmol/L, and the mean time of peak K⁺ was 20 hours. The peak K⁺ occurred after the lowest measured SVC flow in 84% of infants. A significant positive relationship was found between the lowest measured SVC flow and the mean (r = 0.31, P =.001) and peak (r = 0.31, P =.001) K⁺ in the first 24 hours. Low SVC flow at 5 hours best predicted the rate of K⁺ rise (r = 0.28, P =.002) and at 12 hours best predicted the peak K⁺ concentration (r = 0.47, P <.001). The mean minimum SVC flow in the 17 babies who became hyperkalemic was 29.5 mL/kg/min versus 46.2 mL/kg/min in the 102 infants with normokalemia. Urine output in the first 24 hours was significantly lower in the hyperkalemic infants. A K⁺ rate rise exceeding 0.12 mmol/L/h in the first 12 hours predicted low SVC flow with 93% accuracy. Conclusions: The data are consistent with a role for low systemic blood flow leading to reduced urinary output and subsequent hyperkalemia in preterm infants. (J Pediatr 2001;139:227-32)

Section snippets

Patients

Preterm infants (n = 119) born before 30 weeks with a mean gestational age of 27 weeks (range, 23 to 29 weeks) and a mean birth weight of 984 g (range, 420 to 1630 g) had serial whole blood K⁺ measurements taken from indwelling arterial lines; 64% were delivered by cesarean section. Eleven (9%) of 119 were outborn and transferred to our hospital subsequently; 111 of the 119 underwent mechanical ventilation initially. The respiratory diagnoses were normal lungs (n = 20), respiratory distress

K⁺ Measurements

The first K⁺ sample was taken at an average of 3.6 hours in the inborn group and 9.3 hours in the outborn group. In 113 infants there was a steady rise of K⁺ over the study period, and in only 6 was there a fall; 3 of these cases were outborn, and the average time of first measurement was 7 hours, raising the possibility that the peak K⁺ concentration may have already occurred. The mean rate of rise in K⁺ over the first 48 hours was 0.17 mmol/L/h (range, 0 to 1.33 mmol/L/h). The mean peak K⁺

Discussion

This study demonstrated that low SVC flow is strongly associated with early raised blood K⁺ concentrations and lower urine flow rate in preterm infants. The indirect measurement of SVC flow with previously validated Doppler echocardiography was used as an indicator of systemic blood flow.¹⁰ Reduction in the SVC blood flow often occurred many hours before the subsequent increase in blood K⁺ and was associated with oliguria, suggesting that reduced SVC blood flow may be reflecting a reduction in

References (17)

SG Shaffer et al.
Hyperkalemia in very low birth weight infants
J Pediatr
(1992)
J Gruskay et al.
Nonoliguric hyperkalemia in the premature infant weighing less than 1000 grams
J Pediatr
(1988)
JM Lorenz et al.
Potassium metabolism in extremely low birth weight infants in the first week of life
J Pediatr
(1997)
K Sato et al.
Internal potassium shift in premature infants: cause of nonoliguric hyperkalemia
J Pediatr
(1995)
M Kluckow et al.
Relationship between blood pressure and cardiac output in preterm infants requiring mechanical ventilation
J Pediatr
(1996)
N Evans et al.
Assessment of ductus arteriosus shunt in preterm infants supported by mechanical ventilation: effects of interatrial shunting
J Pediatr
(1994)
JL Stefano et al.
Decreased erythrocyte Na+,K(+)-ATPase activity associated with cellular potassium loss in extremely low birth weight infants with nonoliguric hyperkalemia
J Pediatr
(1993)
LM. Satlin
Maturation of renal potassium transport
Pediatr Nephrol
(1991)

There are more references available in the full text version of this article.

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Citation Excerpt :
Urine output on day one is somewhat variable, but its’ presence is reassuring. A previous observational study has found a direct correlation between urinary output, hyperkalemia and superior vena cava flow.23 The reduction in superior vena cava flow often precedes the fall in urinary output and rise in potassium by a few hours, reflecting a fall in systemic blood flow and subsequent glomerular filtration.
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To assess the effect of a protocolised intervention for low systemic blood flow (SBF) in the occurrence of severe intraventricular haemorrhage (IVH) or death in pre-term infants.
A study with a quasi-experimental design with retrospective controls was conducted on pre-term infants of less than 30 weeks of gestational age, born between January 2016 and July 2017, who were consecutively included in the intervention period. The control cohort included pre-term infants (born between January 2013 and December 2015) matched by gestational age, birth weight, and gender (two controls for each case). The cases of low SBF diagnosed according to functional echocardiography during the study period received dobutamine (5-10 μg/kg/min) for 48 hours.
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^*: Supported by North Shore Heart Research Foundation Grant number 03 95/96.

^**: Reprint requests: Martin Kluckow, MBBS, FRACP, Department of Neonatology, Royal North Shore Hospital, Pacific Hwy, Sydney, New South Wales, 2065 Australia.

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Original articlesLow systemic blood flow and hyperkalemia in preterm infants*,**

Abstract

Section snippets

Patients

K+ Measurements

Discussion

J Pediatr

J Pediatr

J Pediatr

J Pediatr

J Pediatr

J Pediatr

J Pediatr

Maturation of renal potassium transport

Pediatr Nephrol

Original articles
Low systemic blood flow and hyperkalemia in preterm infants*,**

K⁺ Measurements