Comparison of Point-of-Care versus Central Laboratory Testing of Electrolytes, Hemoglobin, and Bilirubin in Neonates.

OBJECTIVE: Electrolyte, hemoglobin, and bilirubin values are routinely reported with point-of-care (POC) testing for blood gases. Results are rapidly available and require a small blood volume. Yet, these results are underutilized due to noted discrepancies between central laboratory (CL) and POC testing. The study aimed to determine the correlation between POC and CL measurement of electrolytes, hemoglobin, and bilirubin in neonates. STUDY DESIGN: Electrolyte, hemoglobin, and bilirubin results obtained from capillary blood over a 4-month period were analyzed. Each CL value was matched with a POC value from the same sample or another sample less than 1-hour apart. Agreement was determined by measuring the mean difference (MD) between paired samples with 95% limits of agreement (LOA) and Lin's concordance correlation (LCC). RESULTS: There were 355-paired sodium/potassium, 139 paired hemoglobin, and 197 paired bilirubin values analyzed. POC sodium values were lower (133.5 ± 5.8 mmol/L) than CL (140.2 ± 5.8 mmol/L), p <0.00001 with poor agreement (LCC = 0.49; MD = 6.7; 95% LOA: -13.6 to 0.14). POC potassium values were lower (4.6 ± 0.98 mmol/L) than CL (4.98 ± 1.24mEq/L), p < 0.0001, but with better concordance and agreement. (LCC = 0.6; MD = 0.4; 95% LOA: -2.3 to 1.4). There were no differences in hemoglobin between POC (14.3 ± 3.2 g/dL) and CL (14.4 ± 3.1 g/dL), p = 0.2 with good LCC (0.93) and in bilirubin values between POC (6.0 ± 3.2 mg/dL) and CL (5.8 ± 3.0 mg/dL), MD = 0.18, and p = 0.07. CONCLUSION: POC Sodium values are lower than CL. POC potassium levels are also lower, but the differences may not be clinically important while hemoglobin and bilirubin levels are similar between POC and CL. As POC potassium, hemoglobin, and bilirubin levels closely reflect CL values, these results can be relied upon to make clinical judgments in neonates. KEY POINTS: · Electrolyte, hemoglobin, and bilirubin are available as POC.. · POC sodium and potassium values are lower than CL results.. · Hemoglobin and bilirubin values are similar between POC and CL..

Tidal volume in infants with congenital diaphragmatic hernia supported with conventional mechanical ventilation.

OBJECTIVE: This study aims to test the hypothesis that the tidal volume (VT) required for maintaining eucapnia in infants with congenital diaphragmatic hernia (CDH) is not reduced to the same degree as their lung mass. STUDY DESIGN: Records of infants with CDH admitted to our hospital from 1997 to 2009 managed with conventional ventilation were reviewed. Demographics, ventilator settings, observed VT, respiratory rate (RR), and blood gas values pre- and postsurgery were recorded. Minute ventilation (MV) was calculated as a product of RR × VT. Only VT values with corresponding Paco 2 between 35 and 60 mm Hg were included. Mean VT/kg and MV/kg were calculated for each patient. Forty term/late preterm infants ventilated for lung disease other than CDH or pulmonary hypoplasia served as controls. RESULTS: Birth weights of the 19 patients with CDH and 40 control infants were similar (3,360 ± 480 g and 3,300 ± 640 g). Mean gestational age was 38.5 ± 2 and 37.4 ± 1.5 week, p = 0.02. Infants with CDH required similar VT and MV as controls to maintain equal Paco 2. CONCLUSIONS: Infants with CDH require similar VT to clear their CO2 production compared with infants of similar size without pulmonary hypoplasia. These are the first reference values to guide selection of VT in infants with CDH.

Intrauterine Herpes Simplex Virus Infection Presenting as a Zosteriform Eruption in a Newborn.

There is significant morbidity and mortality associated with the transmission of herpes simplex virus (HSV) from pregnant women to their fetus or newborn. Although most commonly transmitted in the peripartum period, in rare cases HSV can lead to intrauterine infection. Cutaneous lesions are the most common manifestation of intrauterine HSV, and have a wide spectrum of presentation. We present a rare case of intrauterine HSV-2 infection presenting with a zosteriform eruption mimicking congenital varicella syndrome in a newborn.

Volume guarantee ventilation.

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and the association of hypocarbia with neonatal brain injury demonstrate the importance of better control delivered tidal volume. New microprocessor-based ventilator modalities combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. This article discusses automatic weaning of peak inspiratory pressure in response to changing lung compliance and respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocapnia, shorter duration of mechanical ventilation, and lower levels of inflammatory cytokines have been documented in short-term clinical trials. It remains to be seen if these short-term benefits ultimately lead to a reduced incidence of chronic lung disease.

The impact of instrumental dead-space in volume-targeted ventilation of the extremely low birth weight (ELBW) infant.

BACKGROUND: Volume-targeted ventilation is increasingly used in neonatal ventilation to reduce the risk of volutrauma and inadvertent hyperventilation. However, normative data for appropriate tidal volume (V(T)) settings are lacking, especially in extremely low birth weight (ELBW) infants in whom the added dead space (DS) of the flow sensor may be important. OBJECTIVE: To quantify the effect of instrumental dead-space (IDS) on ventilation and to obtain normative data for initial V(T) associated with normocapnia in ELBW infants ventilated with volume guarantee (VG) ventilation. DESIGN/METHODS: Set and measured V(T), respiratory rate (RR) and arterial blood gas values (ABG) were extracted from charts of babies <800 g born between January 2003 and August 2005, who were ventilated with VG. Data were collected at the time of each ABG during the 1st 48 hr of life. Theoretical alveolar minute ventilation (AMV) was calculated as (V(T) - DS) x RR. IDS was measured by filling with water a 2.5 mm endotracheal tube cut to 10 cm with attached hub of the inline suction catheter and flow sensor. We added 0.5 mL/kg to this value to account for distal tracheal/mainstem bronchi DS (anatomical dead space). Descriptive statistics and linear regression were used for analysis. RESULTS: The measured IDS was 2.7 mL. Mean combined DS (instrumental + anatomical) was 3.01 mL. There were 344 paired observations of V(T) and ABG with PaCO(2) in the normocapnic range in 38 infants (mean birth weight 625 g +/- 115 g SD, range 400-790 g) during the study period. The mean pH was 7.30 +/- 0.06 (SD), mean PaCO(2) 43.4 +/- 5.4 Torr. The mean target V(T) was 3.11 +/- 0.64 mL and the measured V(T) was 3.17 +/- 0.73 mL. Despite normocapnia, 47% of the V(T) were equal to or less than estimated DS. Mean theoretical AMV was only 8.7 mL/kg/min. The V(T)/kg needed for normocapnia was inversely related to weight (r = -0.70, P < 0.01), indicating some effect of the fixed IDS. Mean V(T)/kg of infants <500 g was 5.9 +/- 0.3 mL, compared to 4.7 +/- 0.5 mL for those >700 g (P < 0.001). CONCLUSIONS: Effective alveolar ventilation occurs with V(T) at or below calculated DS. This can be explained by the fact that at the high flow rates seen in these tiny infants who have extremely short inspiratory times, fresh gas penetrates through the dead space gas, rather than pushing it ahead. Therefore there is no need to forego synchronized and volume targeted ventilation because of dead space concerns. In infants <800 g, initial V(T) of 5-6 mL/kg was associated with normocapnia when using assist/control or pressure support ventilation.