John Kattwinkel

Mortality reduction by heart rate characteristic monitoring in very low birth weight neonates: A randomized trial

OBJECTIVE To test the hypothesis that heart rate characteristics (HRC) monitoring improves neonatal outcomes. STUDY DESIGN We conducted a two-group, parallel, individually randomized controlled clinical trial of 3003 very low birth weight infants in 9 neonatal intensive care units. In one group, HRC monitoring was displayed; in the other, it was masked. The primary outcome was number of days alive and ventilator-free in the 120 days after randomization. Secondary outcomes were mortality, number of ventilator days, neonatal intensive care unit stay, and antibiotic use. RESULTS The mortality rate was reduced in infants whose HRC monitoring was displayed, from 10.2% to 8.1% (hazard ratio, 0.78; 95% CI, 0.61-0.99; P = .04; number needed to monitor = 48), and there was a trend toward increased days alive and ventilator-free (95.9 of 120 days compared with 93.6 in control subjects, P = .08). The mortality benefit was concentrated in infants with a birth weight <1000 g (hazard ratio, 0.74; 95% CI, 0.57-0.95; P = .02; number needed to monitor = 23). There were no significant differences in the other outcomes. CONCLUSION HRC monitoring can reduce the mortality rate in very low birth weight infants.

Neonatal apnea: Pathogenesis and therapy*

APNEIC ATTACKS in the preterm infant have recently received widespread attention in the medical literature. Physiologists have presented new data regarding the pathogenesis of this disorder, and clinicians have proposed many new forms of therapy. Frequently, however, a new treatment regimen becomes incorporated into nursery routine without regard for alternative, perhaps less invasive, modes of treatment, and often without consideration of the cause of apnea. It is the purpose of this report to review recent concepts regarding the pathogenesis of neonatal apnea and to propose a treatment schema based on counteracting the supposed physiologic aberrations with a minimum of risk.

A new algorithm for detecting central apnea in neonates

Apnea of prematurity is an important and common clinical problem, and is often the rate-limiting process in NICU discharge. Accurate detection of episodes of clinically important neonatal apnea using existing chest impedance (CI) monitoring is a clinical imperative. The technique relies on changes in impedance as the lungs fill with air, a high impedance substance. A potential confounder, however, is blood coursing through the heart. Thus, the cardiac signal during apnea might be mistaken for breathing. We report here a new filter to remove the cardiac signal from the CI that employs a novel resampling technique optimally suited to remove the heart rate signal, allowing improved apnea detection. We also develop an apnea detection method that employs the CI after cardiac filtering. The method has been applied to a large database of physiological signals, and we prove that, compared to the presently used monitors, the new method gives substantial improvement in apnea detection.

Septicemia mortality reduction in neonates in a heart rate characteristics monitoring trial

Background:Abnormal heart rate characteristics (HRC) wax and wane in early stages of culture-positive, late-onset septicemia (LOS) in patients in the neonatal intensive care unit (NICU). Continuously monitoring an HRC index leads to a reduction in mortality among very low birth weight (VLBW) infants. We hypothesized that the reduction in mortality was due to a decrease in septicemia-associated mortality.Methods:This is a secondary analysis of clinical and HRC data from 2,989 VLBW infants enrolled in a randomized clinical trial of HRC monitoring in nine NICUs from 2004 to 2010.Results:LOS was diagnosed 974 times in 700 patients, and the incidence and distribution of organisms were similar in HRC display and nondisplay groups. Mortality within 30 d of LOS was lower in the HRC display as compared with the nondisplay group (11.8 vs. 19.6%; relative risk: 0.61; 95% confidence interval: 0.43, 0.87; P < 0.01), but mortality reduction was not statistically significant for patients without LOS. There were fewer large, abrupt increases in the HRC index in the days leading up to LOS diagnosis in infants whose HRC index was displayed.Conclusion:Continuous HRC monitoring is associated with a lower septicemia-associated mortality in VLBW infants, possibly due to diagnosis earlier in the course of illness.

Anemia, Apnea of Prematurity, and Blood Transfusions

OBJECTIVE To compare the frequency and severity of apneic events in very low birth weight (VLBW) infants before and after blood transfusions using continuous electronic waveform analysis. STUDY DESIGN We continuously collected waveform, heart rate, and oxygen saturation data from patients in all 45 neonatal intensive care unit beds at the University of Virginia for 120 weeks. Central apneas were detected using continuous computer processing of chest impedance, electrocardiographic, and oximetry signals. Apnea was defined as respiratory pauses of >10, >20, and >30 seconds when accompanied by bradycardia (<100 beats per minute) and hypoxemia (<80% oxyhemoglobin saturation as detected by pulse oximetry). Times of packed red blood cell transfusions were determined from bedside charts. Two cohorts were analyzed. In the transfusion cohort, waveforms were analyzed for 3 days before and after the transfusion for all VLBW infants who received a blood transfusion while also breathing spontaneously. Mean apnea rates for the previous 12 hours were quantified and differences for 12 hours before and after transfusion were compared. In the hematocrit cohort, 1453 hematocrit values from all VLBW infants admitted and breathing spontaneously during the time period were retrieved, and the association of hematocrit and apnea in the next 12 hours was tested using logistic regression. RESULTS Sixty-seven infants had 110 blood transfusions during times when complete monitoring data were available. Transfusion was associated with fewer computer-detected apneic events (P < .01). Probability of future apnea occurring within 12 hours increased with decreasing hematocrit values (P < .001). CONCLUSIONS Blood transfusions are associated with decreased apnea in VLBW infants, and apneas are less frequent at higher hematocrits.

Interrelationship of atrial natriuretic peptide, atrial volume, and renal function in premature infants.

Infants experience dramatic changes in fluid balance during the first few days of life, which provides an opportunity to observe the interrelationships of changing atrial size, atrial natriuretic peptide (ANP) secretion, and renal function during a relatively short period. To study these relationships, we examined nine infant boys (mean birth weight 1180 gm and gestational age 30 weeks) at 20 to 28 hours of age and then at four 24-hour intervals. Measurements included plasma ANP concentration, two-dimensional echocardiographic estimations of left and right atrial volumes, Doppler determination of ductus arteriosus patency, creatinine clearance, urine flow rate, urinary sodium excretion, and cyclic guanosine monophosphate (cGMP) excretion. Plasma ANP concentration was found to decrease with age and to correlate with decreasing size of the right atrium, closure of the ductus arteriosus, urinary cGMP excretion, and sodium excretion. We speculate that elevated plasma ANP values in a preterm neonate reflect an expanded volume state. As volume contraction, reflected by decreasing atrial volume and body weight occurs, ANP levels decrease, which may diminish diuresis. These findings are compatible with a significant role for ANP in volume homeostasis of newborn infants.

Accurate automated apnea analysis in preterm infants.

OBJECTIVE In 2006 the apnea of prematurity (AOP) consensus group identified inaccurate counting of apnea episodes as a major barrier to progress in AOP research. We compare nursing records of AOP to events detected by a clinically validated computer algorithm that detects apnea from standard bedside monitors. STUDY DESIGN Waveform, vital sign, and alarm data were collected continuously from all very low-birth-weight infants admitted over a 25-month period, analyzed for central apnea, bradycardia, and desaturation (ABD) events, and compared with nursing documentation collected from charts. Our algorithm defined apnea as > 10 seconds if accompanied by bradycardia and desaturation. RESULTS Of the 3,019 nurse-recorded events, only 68% had any algorithm-detected ABD event. Of the 5,275 algorithm-detected prolonged apnea events > 30 seconds, only 26% had nurse-recorded documentation within 1 hour. Monitor alarms sounded in only 74% of events of algorithm-detected prolonged apnea events > 10 seconds. There were 8,190,418 monitor alarms of any description throughout the neonatal intensive care unit during the 747 days analyzed, or one alarm every 2 to 3 minutes per nurse. CONCLUSION An automated computer algorithm for continuous ABD quantitation is a far more reliable tool than the medical record to address the important research questions identified by the 2006 AOP consensus group.

Sensing and responding to compliance changes during manual ventilation using a lung model: can we teach healthcare providers to improve?

OBJECTIVE To test the hypothesis that an educational intervention would improve the resuscitators ability to provide on-target volume ventilation during pulmonary compliance changes. STUDY DESIGN Neonatal professionals (n = 27) ventilated an electromechanical lung model simulating a 3-kg baby while targeting a tidal volume of 4-6 mL/kg. In this preintervention and postintervention study, a one-on-one educational intervention aimed to improve the primary outcome of on-target tidal volume delivery during high and low compliance. Seventeen subjects were retested 8 months later. RESULTS When only pressure was displayed, and using a self-inflating bag, participants improved from a mean of 6% of breaths on-target to 21% immediately after education (P < .01). Using a flow-inflating bag, participants improved from 1% to 7% of breaths on-target (P < .01). Eight-month retention testing demonstrated no difference compared with baseline. With volume displayed, the mean baseline success rate was 84% with the self-inflating bag and 68% with the flow-inflating bag. There was no significant change after education or at 8-month follow-up. CONCLUSION When pressure is displayed, resuscitators can improve their ability to respond to changes in compliance after an educational intervention. When volume is displayed, performance is markedly better at baseline, but not improved after the intervention. Our findings reconfirm that resuscitation bags should have volume displays.

Clinical associations of immature breathing in preterm infants: part 1—central apnea

Background:Apnea of prematurity (AOP) is nearly universal among very preterm infants, but neither the apnea burden nor its clinical associations have been systematically studied in a large consecutive cohort.Methods:We analyzed continuous bedside monitor chest impedance and electrocardiographic waveforms and oxygen saturation data collected on all neonatal intensive care unit (NICU) patients <35 wk gestation from 2009 to 2014 (n = 1,211; >50 infant-years of data). Apneas, with bradycardia and desaturation (ABDs), defined as central apnea ≥10 s associated with both bradycardia <100 bpm and oxygen desaturation <80%, were identified using a validated automated algorithm.Results:Number and duration of apnea events decreased with increasing gestational age (GA) and postmenstrual age (PMA). ABDs were more frequent in infants <31 wk GA at birth but were not more frequent in those with severe retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), or severe intraventricular hemorrhage (IVH) after accounting for GA. In the day before diagnosis of late-onset septicemia and necrotizing enterocolitis, ABD events were increased in some infants. Many infants continued to experience short ABD events in the week prior to discharge home.Conclusion:Frequency of apnea events is a function of GA and PMA in infants born preterm, and increased apnea is associated with acute but not with chronic pathologic conditions.

Providing Free Samples of Baby Items to Newly Delivered Parents An Unintentional Endorsement

Recent studies have suggested that providing free sample packs of baby items to newly delivered parents may adversely influence parental health behavior. To determine the extent of this practice in Virginia, the head nurses of all 68 newborn nurseries and a random sample of 200 pediatricians were surveyed. Formula samples were being distributed at all hospitals. Formula packs were given to breast-feeding mothers at 65 (95%) hospitals although only 66 percent of the surveyed pediatricians approved of this practice. Samples of baby items other than formula (e.g., baby powder) were being distributed at 66 (97%) hospitals. Some physicians (18%) objected to the distribution of these non-formula samples, and others were not familiar with the content of these packs. In most instances, the hospital medical staff had not voted to approve the distribution of these packs. Parents were being informed only rarely about the source and intent of the packs. The provision of sample packs to newly delivered parents affects approximately 3,000,000 babies each year in the United States. The short- and long-term effects of providing these packs have been inadequately explored. Physicians should make an active decision whether to distribute sample packs. Those physicians choosing to dispense these samples may wish to review and edit the content of the packs and to enclose in the pack a brief note explaining that the provision of the products does not constitute a medical endorsement.