Infection and Other Clinical Correlates of Abnormal Heart Rate Characteristics in Preterm Infants

Abstract

Objective Identify clinical conditions associated with a large increase (spike) in the heart rate characteristics index in VLBW infants. Study design Retrospective medical record review within a day of all large heart rate characteristics index spikes (increase of ≥3 from prior 5 day average) in VLBW infants at a single center enrolled from 2007–2010 in a multicenter trial of heart rate characteristics monitoring. In the trial, infants were randomized to having their heart rate characteristics index displayed to clinicians or not displayed. Results Of 274 eligible infants, 224 large heart rate characteristics spikes occurred in 105 infants. Thirty-three spikes were associated with surgery or procedures requiring anesthetic or anticholinergic medications, and infection-related conditions were the most common clinical association with the other spikes. Of the first spikes in 47 infants randomized to conventional monitoring (heart rate characteristics index not displayed to clinicians), 53% were associated with suspected or proven infection. Respiratory deterioration without suspected infection occurred with 34%, and no association was identified in 13%. Infants randomized to having their heart rate characteristics index displayed were more likely to have antibiotics initiated around the time of a large heart rate characteristics index spike. Conclusions Sepsis, other infectious or systemic inflammatory conditions, respiratory deterioration, and surgical procedures are the most common clinical associations with a large increase in the heart rate characteristics index in VLBW infants. This information may improve use of heart rate characteristics monitors in NICU patients.

Predictive monitoring for sepsis and necrotizing enterocolitis to prevent shock

“…Excluding cases of surgery, 53% of HRC index spikes were associated with suspected or proven infection (including urinary tract infection) or NEC. Thirty-four percent of the spikes were associated with acute respiratory deterioration without infection [40]. In some infants, there were increased apneic spells with associated heart rate decelerations but in other cases infants were on mechanical ventilation, in which case the abnormal heart rate characteristics may have been due to acute lung inflammation, respiratory acidosis, or hypoxemia.…”

“…For example, infants with grade III-IV intraventricular hemorrhage [41] and those with significant lung disease [40] may have a high score with frequent spikes for several weeks after birth (see Case 4). For infants with a chronically elevated HRC index, other clinical variables and laboratory tests must be used in decisions about obtaining cultures and administering antibiotics.…”

Heart rate characteristic index monitoring for bloodstream infection in an NICU: a 3-year experience

“…7 In a site-specific analysis of patients enrolled in the RCT, 22% of patients with 'spikes', defined as sharp rises (>3) in the HRC index, developed necrotising enterocolitis or culture-positive infection (urine or blood). 8 Infants with spikes were more likely to have antimicrobial treatment initiated. In an editorial that accompanied the publication of the RCT, the authors asked "will the benefits transfer beyond the clinical trial environment in general neonatal practice?"…”

Adverse consequences of neonatal antibiotic exposure

“…[84, 85*] In the multicenter randomized trial of visible results from heart rate characteristic monitoring vs. blinded data collection, 30 day mortality among infected infants was 10% among those with displayed heart rate characteristics, and 16% among controls (p = 0.01). Investigators also found that the number of sepsis work-ups and days of antibiotics total in both groups were similar.…”