Dose end-tidal carbon dioxide measurement correlate with arterial carbon dioxide in extremely low birth weight infants in the first week of life?

OBJECTIVE: To study the correlation and agreement between end-tidal carbon dioxide (EtCO2) and arterial carbon dioxide (PaCO(2)) in ventilated extremely low birth weight (ELBW) infants in the first week of life. METHODS: Retrospective chart review of all ELBW (<1,000 g) infants admitted to a level III NICU from January 2003 to December 2003. Data collected included demographic details and simultaneous EtCO(2) (mainstream capnography) and arterial blood gas values (pH, PaCO(2), PaO(2)). Outcome: The correlation coefficient, degree of bias with 95% confidence interval between the EtCO(2) and PaCO(2). RESULTS: There were 754 end-tidal and arterial CO(2) pairs from 31 ELBW infants (21 male and 10 female). The overall EtCO(2) values were significantly lower than PaCO(2) value. In only 89/754(11.8%) pairs, the EtCO(2) was higher than the PaCO(2). The overall bias was 5.6 +/- 6.9 mmHg (95% C.I. 5.11-6.09). The intraclass correlation coefficient was 0.81. Using EtCO2 ranges of 30 to 50 mmHg, the capnographic method was able to identify 84% of instances where PaCO(2) was between 35 (<35 = hypocarbia) and 55 mmHg (>55= hypercapnia). Conclusions: There is good correlation and agreement between end-tidal CO(2) and arterial CO(2) in ELBW infants in the EtCO(2) range 30-50 mmHg. End-tidal CO(2) monitoring can be helpful in trending or for screening abnormal PaCO(2) values in ELBW infants in first week of life.

Umbilical cord blood and neonatal endothelin-1 levels in preterm newborns with and without respiratory distress syndrome

Increased pulmonary vascular resistance in preterm newborn infants with respiratory distress syndrome is suggested, and endothelin-1 plays an important role in pulmonary vascular reactivity in newborns. We determined umbilical cord blood and neonatal (second sample) levels of endothelin-1 in 18 preterm newborns with respiratory distress syndrome who had no clinical or echocardiographic diagnosis of pulmonary hypertension and 22 without respiratory distress syndrome (gestational ages: 31.4 ± 1.6 and 29.3 ± 2.3 weeks, respectively). Umbilical cord blood and a second blood sample taken 18 to 40 h after birth were used for endothelin-1 determination by enzyme immunoassay. Median umbilical cord blood endothelin-1 levels were similar in both groups (control: 10.9 and respiratory distress syndrome: 11.4 pg/mL) and were significantly higher than in the second sample (control: 1.7 pg/mL and respiratory distress syndrome: 3.5 pg/mL, P < 0.001 for both groups). Median endothelin-1 levels in the second sample were significantly higher in children with respiratory distress syndrome than in control infants (P < 0.001). There were significant positive correlations between second sample endothelin-1 and Score for Neonatal Acute Physiology and Perinatal Extension II (r = 0.36, P = 0.02), and duration of mechanical ventilation (r = 0.64, P = 0.02). A slower decline of endothelin-1 from birth to 40 h of life was observed in newborns with respiratory distress syndrome when compared to controls. A significant correlation between neonatal endothelin-1 levels and some illness-severity signs suggests that endothelin-1 plays a role in the natural course of respiratory distress syndrome in preterm newborns.

Predictors of fatality in neonates requiring mechanical ventilation.

OBJECTIVE: To evaluate initial arterial blood gas, pulmonary pressures, pulmonary mechanics (compliance and resistance), pulmonary volumes, oxygenation indices and serum carotenoid levels as predictors of fatality in mechanically ventilated neonates. DESIGN: Cross Sectional. SETTING: Referral neonatal unit of a teaching hospital. SUBJECTS: 83 mechanically ventilated outborn neonates. METHODS: 83 neonates consecutively put on mechanical ventilator from March to December 2001 were enrolled in the study. The mechanical ventilator used was pressure limited time cycled ventilator with facility for online measurement of volumes and pulmonary mechanics. Arterial blood gas after half an hour of initiation of mechanical ventilation and initial pulmonary pressures, pulmonary compliance, resistance and duration of mechanical ventilation were recorded in a pre structured proforma. Initial serum carotenoid levels were also measured using spectrophotometric method. The neonates were regularly followed up for outcome. Multiple logistic regression analysis was done to find out the predictors of fatality for those variables that were significantly associated with outcome on univariate analysis. RESULTS: On univariate analysis weight ( < 2000 g), gestational age <34 weeks, pH <7.3, duration of mechanical ventilation <72 hours, a/A <0.25, compliance <1 mL/cmH2O, fraction of inspired oxygen (FiO2) >60%, oxygenation index >10, AaDO2 >250 and serum carotenoid levels < 100 microg/dL were significantly associated with fatality in neonates requiring mechanical ventilation. However, on multiple regression analysis only FiO2, gestational age and serum carotenoids < 100 microg/dL were found to be independent predictors of fatality. CONCLUSIONS: Initial FiO2 > 60%, gestational age <34 weeks and initial serum carotenoid levels < 100 microg/dL were independent predictors of fatality in neonatal mechanical ventilation. Even in a setting with high fatality rates, high risk of mortality in mechanically ventilated neonates can be identified.

Kinetics of theophylline in apnea of prematurity in small for gestational age babies.

OBJECTIVES: To study the pharmacokinetics of theophylline and its correlations to pharmacodynamic effects in apnea of prematurity in small for gestational age babies. DESIGN: Prospective case control study. SETTING: Level III Neonatal Intensive Care Unit. SUBJECTS: Ten small for gestational age (SGA) babies and 10 gestation matched appropriate for gestational age (AGA) babies with recurrent apnea of prematurity. METHODS: All babies were investigated to exclude secondary causes of apnea. 5 mg/kg of aminophylline loading dose followed by 2 mg/kg as maintenance dose every 8 hourly intravenously was used. The trough and peak levels of theophylline were assessed on different days of therapy. Clinical monitoring was done for the efficacy and toxicity of the drug. Analysis was done using unpaired Student's 't' test and the correlation between plasma theophylline levels of different days was performed by using ANOVA. RESULTS: The therapeutic drug levels were achieved within 24 hours in all babies. The SGA babies showed 25% higher drug levels as compared to AGA babies. The mean trough plasma theophylline levels ranged from 8.15 +/- 1.59 to 12.37 +/- 1.54 micrograms/ml in SGA babies while in AGA babies they ranged from 6.26 +/- 1.93 to 9.96 +/- 1.96 micrograms/ml in first 8 days of therapy. The mean peak levels in SGA babies ranged from 11.91 +/- 1.84 to 17.13 +/- 1.63 micrograms/ml and in AGA babies ranged from 8.17 +/- 1.84 to 13.02 +/- 1.48 micrograms/ml. Twenty per cent SGA and AGA babies each developed clinical toxicity though toxic drug levels were found in 50% SGA and 30% AGA babies. CONCLUSION: There is a need to modify dosage schedule for these babies.

Cord blood cortisol levels and respiratory distress syndrome.

Cord blood cortisol levels were analyzed in 121 neonates, using a "Coat a Count" RIA kit. Forty two appropriate for gestation age (AGA) preterms < 34 weeks who had not received antenatal dexamethasone constituted Group A, 32 AGA preterms < 34 weeks gestation who had received dexamethasone antenatally comprised Group B, while Group C consisted of 47 term normal neonates. Cortisol levels were compared in these 3 groups and correlated to the development of respiratory distress syndrome (RDS). It was observed tht preterms (Groups A and B) had significantly (p < 0.005) lower levels (8.45 +/- 6.31 micrograms/dl) compared to term neonates (11.67 +/- 4.68 micrograms/dl). Antenatal dexamethasone therapy did not significantly alter cortisol levels within the group of preterms. There was a significant difference (p < 0.02) in cortisol levels between those preterms who developed RDS (5.41 +/- 4.91 micrograms/dl) and those who did not (9.58 +/- 6.45 micrograms/dl). Preterms (Grous A and B) who did not develop RDS had cortisol levels comparable to term neonates. There was a significant reduction in the incidence of RDS (p < 0.05) in preterms who had received antenatal dexamethasone. Cord blood cortisol levels < or = 7 micrograms/dl had a positive predictive accuracy of 36.59% and negative predictive accuracy of 93.75% in predicting onset of RDS.

High-frequency flow interruption in the rescue of preterm infants with severe RDS.

High-frequency flow interruption (HFFI) was used successfully to rescue three preterm infants with severe respiratory distress syndrome (RDS) whose clinical condition continued to deteriorate while on the conventional mechanical ventilation. Had the HFFI not been used, the survival chances might have been 25 per cent for Case 1 and 2, and 45.5 per cent for Case 3. A dramatic, immediate, and sustained improvement in ventilation and oxygenation was demonstrated once the critical frequency and amplitude of HFFI were established. Bronchopulmonary dysplasia which was already evidenced in one infant before the HFFI attempt was detected in two infants. This study demonstrates that HFFI is capable of achieving adequate gas exchange and improving survival in infants with severe RDS.

Actividad de la anhidrasa carbónica eritrocitaria en recién nacidos a término y prematuros / Activity of red cell carbonic anhydrase in preterm and at term newborn infants

Se determinaron los valores normales de actividad enzimática de anhidrasa carbónica eritrocitaria en adultos (X ñ 1 DE: 6546,4 ñ 1272,4 U/10 a la 7 hematíes), recién nacidos a término (X ñ 1 DE: 1694,8 ñ 1092,9 U/10 a la 7 hematíes) y prematuros (menos de 34 semanas X ñ 1 DE: 1025 ñ 873,2 y más de 34 semanas X ñ 1 DE: 1420,6 ñ 471,3), así como el comportamiento evolutivo en recién nacidos y prematuros de distintas edades gestacionales. Los prematuros con síndrome de distress respiratorio al nacer presentaron valores de anhidrasa carbónica muy bajos en comparación con los obtenidos en los grupos controles, por lo que se sugiere que la determinación de anhidrasa carbónica es útil para el diagnóstico de esta enfermedad

Hormonas tiroideas en suero del cordón umbilical y síndrome de distress respiratorio idiopático / Thyroid hormonal in umbilical cord serum and idiopathic respiratory distress syndrome

En el presente trabajo los autores determinan por "Radioinmunoensayo" los niveles séricos de tiroxina total (T4) en 106 mujeres gestantes durante el parto. Se registró en 40 con embarazo a término normales, promedio de 7.79ug/100ml; en 41 pretérminos sanos 7.28ug/100ml y en 25, cuyos hijos cursaron con distress respiratorio 7.21 ug/100ml. Se reportaron promedios de 5.8ug/100ml, de tiroxina total (T4), 32% de tri-yodo-tironina (T3) y 1.98 de tiroxina libre (FT4) en suero de cordón umbilical, en los 40 neona os a término normales. 5.01ug/100ml, 30% y 1.50 para los 41 neonatos pretérminos sanos y 3.8ug/100ml, 25% y 1.00 para los 25 prematuros con distress respiratorio idiopático. Se encontró diferencia significativa (P <0.01) entre los promedios de tiroxina total(T4) entre los embarazos pretérminos y a términos, no encontrándose entre las gestantes pretérminas. Se demostró estadísticamente diferencia significativa entre los promedios de T4, T3 y FT4 en cordón umbilical, en la comparación de los promedios en neonatos a término y los pretérminos sanos y patológicos; y entre los dos últimos (P <0.01). Se demostró diferencia estadísticamente significativa (P <0.01) en el estudio comparativo de promedios de T4 (tiroxina total) y FT4 (tiroxina libre) en cordón umbilical, tanto en los neonatos prematuros sanos y con membranas hialina pulmonar, según las diferentes semanas de gestación y entre ambos grupos, por ser más bajo en los patológicos. Se encontró incremento de los niveles de tiroxina total (T4) en neonatos a términos y pretérminos sanos y algunos que sobrevivieron a las 24 y 48 horas de vida, sin observarse en los que murieron con distress respiratorio. Se concluye en base a los resultados sobre el posible papel que puede jugar las hormonas tiroideas, en la maduración bioquímica del pulmón, al promover la síntesis de los componenete del complejo surfactante por el neumocito alveolar tipo II; y en la profilaxis del distress respiratorio idiopático o membrana hialina pulmonar en el recién nacido