Cardiac output changes secondary to theophylline therapy in preterm infants

The cardiovascular effects of theophylline were studied in 11 clinically stable preterm infants. Theophylline was given as aminophylline using a loading dose of 6.8 mg/kg and a maintenance dose of 2 mg/kg every 8 hours intravenously. Cardiac output, stroke volume, and heart rate were measured using a combination of pulsed Doppler ultrasound and M-mode echocardiography. Compared with day 0, an increase was found in both cardiac output (P less than 0.01) and stroke volume (P less than 0.02) on days 1, 2, and 3. By day 7, stroke volume was comparable to pretreatment values, whereas cardiac output was still increased. Heart rate was augmented significantly (P less than 0.01) throughout the treatment period. Mean arterial blood pressure did not change. All but one of the neonates had serum theophylline concentrations between 6 and 13 mg/L. We conclude that both inotropic and chronotropic effects are evident during the first days of theophylline therapy. The metabolic cost of the increased cardiac output in the preterm infant with theophylline therapy deserves further attention.     

Skin bilirubin measurement during phototherapy in preterm and term newborn infants

Background

The few existing studies evaluating the reliability of transcutaneous bilirubin monitoring during phototherapy gave controversial results.

Aims

To evaluate the accuracy of transcutaneous bilirubin measurement in a large population of newborn infants, during phototherapy.

Study design and methods

Total serum bilirubin and transcutaneous bilirubin on patched and unpatched skin areas were simultaneously measured in newborn infants undergoing phototherapy. Transcutaneous measurements were performed with a multiwavelength transcutaneous bilirubinometer (Respironics BiliCheck™). The Passing-Bablok regression and the Bland-Altman plot were used to estimate the relationship between serum and transcutaneous bilirubin.

Results

We studied 364 newborn infants with a mean (SD) gestational age of 34.6 (3) weeks and a mean birth weight of 2371 (805) grams. Total serum bilirubin, patched transcutaneous bilirubin and unpatched transcutaneous bilirubin were similar before phototherapy. After 52 (33) hours of phototherapy, the difference between serum bilirubin and patched transcutaneous bilirubin was 0.2 (3.1) mg/dL (not significant) while the difference between serum bilirubin and unpatched transcutaneous bilirubin was 3.2 (3.0) mg/dL (p < 0.001). Statistical analysis showed a good agreement between serum bilirubin and patched transcutaneous bilirubin, while unpatched transcutaneous bilirubin underestimates serum levels. The difference between patched and unpatched values was significantly lower in preterm than in term infants (2.8 mg/dL vs. 3.6 mg/dL; p < 0.001).

Conclusion

BiliCheck can be safely used for the evaluation of bilirubin levels in newborn infants under phototherapy. Its reliability on patched skin of the forehead is high enough to consistently reduce blood draws and to ascertain when to discontinue phototherapy. Because of the individual variance, any clinical decision has to be taken on the basis of the transcutaneous bilirubin trend more than on a single value.     

Transepidermal water loss during halogen spotlight phototherapy in preterm infants

Among preterm infants there is a relationship between skin blood flow and transepidermal water loss (TEWL). The aim of this study was to assess whether halogen spotlight phototherapy without significant heat stress increases TEWL and affects maintenance fluid requirements in preterm infants. TEWL was measured noninvasively before the start and after 1 h of halogen spotlight phototherapy in a group of preterm infants, nursed in double-walled incubators with moderately high relative humidity. Relative humidity and ambient temperature in the incubator were tightly controlled. Mean +/- SD birth weight of the 18 infants was 1412 +/- 256 g, gestational age 30.6 +/- 1.6 wk, and age at measurement 5 +/- 3 d. Nine infants received ventilatory assistance. Relative humidity was 40-80% (mean 52%). Average TEWL increased from 13.6 to 16.5 g/m(2)/h during phototherapy. These data show that TEWL increases by approximately 20% during phototherapy despite constant skin temperature and relative humidity. Maintenance fluids of preterm infants should be increased by 0.35 mL/kg/h during exposure to halogen spotlight phototherapy.     

Insensible water loss from the skin during phototherapy in term and preterm infants

The rate of evaporation from the skin was measured before and during phototherapy in 10 full-term and seven preterm infants (gestational age 29-33 weeks). The method for measurement of rate of evaporation was non-invasive and was based on determination of the water vapour pressure gradient close to the skin surface. All infants were studied naked in an incubator with an ambient relative humidity of 50% and with a controlled environment with respect to temperature and air velocity. In the term infants the mean rate of evaporation, measured from an interscapular skin area, was 3.1 g/m2h both before and after 30 min of phototherapy. In the preterm infants the corresponding value was 9.8 g/m2h before and 9.7 g/m2h after 120 min of phototherapy. Thus, in thermally stable infants, non-ionizing radiation from phototherapy equipment does not increase water loss from the skin.     

Skin exposure during conventional phototherapy in preterm infants: A randomized controlled trial

OBJECTIVE: To assess the effect of reduced skin exposure in preterm infants receiving overhead phototherapy treatment on total serum bilirubin (TSB). METHODS: Randomized controlled trial. Preterm infants (>1500 g birthweight and < or = 36 weeks gestation) were randomized to being nursed either partially clothed with only disposable nappies and in posturally supported positions (n = 30) or naked without postural support (n = 29). Primary outcome was mean TSB percentage change at 24 h of completed conventional overhead phototherapy treatment (irradiance of 6 microW cm(-2)/nm at a wavelength of 425-475 nm). The incidence of rebound jaundice, number of infants continuing to receive phototherapy treatment at 24 h periods, parental stress, mother-infant interaction and mean TSB percentage change at 24 h of completed conventional overhead phototherapy treatment were examined. RESULTS: Mean TSB percentage change at 24 h of completed treatment for the partially clothed group was 15.4% (+/-18) and for the naked group 19% (+/-15) (mean difference 3.6% 95% CI -5.1, 12.3). No other outcomes were significantly affected by reduced skin exposure to overhead phototherapy treatment. CONCLUSION: Our results show no statistically significant difference in TSB level change using either nursing practice.     

BiliBlanket phototherapy system versus conventional phototherapy: A randomized controlled trial in preterm infants

Objective: This study compares the use of standard overhead fluorescent phototherapy units with the BiliBlanket a woven fibreoptic pad which delivers high intensity light with no ultraviolet or infrared irradiation in the treatment of jaundice in preterm infants.
Methodology: We chose to study infants between 800 and 2500 g, with strict criteria for commencing and ceasing phototherapy. Serum bilirubin levels were followed at 12–24 h intervals until 24 h after cessation of phototherapy. Infants were allocated at random to receive either conventional phototherapy or the BiliBlanket.
Results: There were 24 infants in the conventional group and 20 in the BiliBlanket group. Mean duration of phototherapy was compared and was 44 h for the conventional group versus 42 h for the BiliBlanket group.
Conclusions: We have shown that the BiliBlanket is as effective as conventional phototherapy and was well accepted by nursing staff and parents.     

Cardiac output changes in newborns with hyperbilirubinemia treated with phototherapy

Phototherapy is known to increase peripheral blood flow in neonates, but information on the associated cardiovascular effects is not available. Using pulsed Doppler echocardiography we evaluated cardiac output and stroke volume in 12 preterm and 13 term neonates during and after phototherapy. We concomitantly measured arterial limb blood flow by strain gauge plethysmography and skin blood flow by photoplethysmography. Cardiac output decreased by 6% due to reduced stroke volume during phototherapy, whereas total limb blood flow and skin blood flow increased by 38% and 41%, respectively. Peripheral blood flow increments tended to be higher in the preterm than in the term infants. The reduced stroke volume during phototherapy may be an expression of reduced activity of the newborn during phototherapy. For healthy neonates the reduction in cardiac output is minimal, but for sick infants with reduced cardiac output, this reduction may further aggravate the decrease in tissue perfusion.     

Fibre optic versus conventional phototherapy for hyperbilirubinaemia in preterm infants

Studies comparing efficacy of fibre optic phototherapy to conventional phototherapy are performed mostly in term infants and give conflicting results. This randomized prospective study compares efficacy of fibre optic phototherapy using the Ohmeda Biliblanket device to conventional fluorescent phototherapy in preterm infants. A total of 124 preterm infants with a nonhaemolytic hyperbilirubinaemia were evaluated. Stratification at randomisation was performed according to birth weight (<1000 g, 1000–1500 g or 1500–2000 g). Fifty-six infants received fibre optic and 68 conventional phototherapy. Efficacy was assessed by comparing the required duration of phototherapy. Median duration of phototherapy was 118 h and 114 h in the fibre optic and conventional groups respectively, the difference in which was not statistically significant. The median durations were also not significantly different within the separate weight groups. The number of infants requiring exchange transfusions was similar in both treatment groups. Conclusion The efficacy of fibre optic phototherapy in preterm infants is comparable to conventional phototherapy. Received: 14 May 1996 and in revised form: 20 June 1997 / Accepted: 23 June 1997     

Cardiac slowing and respiratory arrest in preterm infants

Changes in respiration and heart rate during sleep states have been recorded by a polygraphic device in healthy preterm infants. Cardiac slowing/bradycardia often coincide with respiratory arrest/apnea. Bradycardia starts early during apneic spells. The incidence of respiratory arrest and cardiac slowing and their simultaneous occurrence is significantly increased by the active or REM sleep state. The physiologic, inhibitory mechanisms of active sleep suggest a neurogenic etiology of episodes of cardiac slowing/bradycardia and/or respiratory arrest/apnea in prematures.Supported by the Deutsche Forschungsgemeinschaft SFB 33.     

Early ductal shunting and intraventricular haemorrhage in ventilated preterm infants.

AIM: To establish if there is an association between early cardiovascular adaptation and intraventricular haemorrhage (IVH). METHODS: One hundred and seventeen ventilated preterm infants (mean gestational age 27 weeks, mean birthweight 993 g) were studied echocardiographically within the first 36 hours. Measurements included right (RVO) and left ventricular outputs (LVO), ductus arteriosus (PDA) and atrial shunt diameter using colour Doppler and pulsed Doppler direction and velocity of both shunts. Clinical variables collected over the first 24 hours included use of antenatal steroids, respiratory severity, and mean blood pressure. Cerebral ultrasound scans were reported by a radiologist blinded to clinical and echocardiographic data. RESULTS: Antenatal steroids (two doses) had been given to 73% of the 86 infants with no IVH compared with 48% of the 21 infants with grades 1 and 2 IVH, and just 10% of 10 babies with grades 3 and 4 (P < 0.05). Both groups with IVH had significantly larger PDA diameters than the group with no IVH. Infants with grades 3 and 4 IVH had significantly lower RVO than the other infants. These differences were more pronounced when only infants with definite late IVH were analysed. Logistic regression analysis showed lack of antenatal steroids and larger PDA diameters were significantly associated with any grade of IVH and lack of antenatal steroids; lower RVO was significantly associated with grades 3 and 4 IVH. CONCLUSIONS: Larger early PDA shunts, lower RVO, and lack of antenatal steroids were significantly associated with IVH.     

Effect of phototherapy in preterm infants on growth in the neonatal period

A total of 120 preterm infants were randomly divided at 24 hr of age into three groups: Group I, controls; Group II, continuous phototherapy for 5 days; and Group III, intermittent phototherapy (12 hr on and 12 hr off) for 5 days. At the end of week 1 80% of the control group regained and surpassed their birth weight as opposed to 44 and 57.6% in the continuous and intermittent phototherapy groups, respectively. In weeks 2 and 3 both phototherapy groups had greater weight gain than the control group. Similar but less marked differences were observed in body lenth and head circumference in the three groups. Data suggest decreased growth during phototherapy with subsequent catch-up in growth during weeks 2 and 3. Differences were less marked between infants on intermittent (rather than continuous) phototherapy and controls. Increased metabolic demands and decreased intestinal absorption during phototherapy may be two of the factors responsible for the observed differences in growth in the three groups.     

Cardiac output measured by thermodilution in infants and children

To determine the accuracy and reproducibility of cardiac output determination by thermodilution (COT) in children, simultaneous outputs were measured by the Fick technique (COF) (using measured oxygen consumption) and thermodilution in 26 children, ranging in age from 8 to 86 months, who were undergoing cardiac catheterization. There was excellent correlation between mean output by thermodilution and by the Fick technique: COT = 1.10 COF -- 0.2 l/minute, R = 0.91. In three-quarters of the patients with COT differed by 15% or less and in none differed by more than 25%. Serial values of thermodilution outputs were reproducible in each patient with a SD of 5.5%. Our observations indicate that COT is accurate, reproducible, and valuable in the care of critically ill infants and children.     

Cardiac output in infants of insulin-dependent diabetic mothers

The purpose of our study was to quantitate left ventricular outflow obstruction in the infant of the diabetic mother (IDM) through estimation of cardiac output by pulsed Doppler ultrasound. We evaluated 42 IDMs (White class B, C, or D) and compared them with two control groups, one similar in birth weight and the other similar in gestational age. Ventricular septal hypertrophy was found in 18 (43%) of 42 of the IDMs, but in none of the control infants. Morbidity increased with advancing septal thickness. None had hyaline membrane disease. Twenty-nine IDMs were asymptomatic, 11 of whom had septal hypertrophy. Thirteen IDMs developed congestive heart failure, seven of whom had septal hypertrophy. Cardiac output per kilogram diminished linearly with increasing septal thickness (r = -0.78, P less than 0.001) secondary to reduced stroke volumes at comparable heart rates. The IDMs had higher left atrial/aortic ratios and greater right ventricular systolic time intervals than the control infants. We conclude that cardiac output is significantly reduced in IDMs with septal hypertrophy. This reduction is secondary to reduced stroke volume and is directly related to the degree of septal hypertrophy.     

光疗对早产儿血内皮素及一氧化氮水平的影响及临床意义

目的观察光疗对早产儿血内皮素(ET)和一氧化氮(NO)水平的影响。方法以64例符合光疗条件的高未结合胆红素血症早产儿为研究对象,其中胎龄>32周组31例,胎龄≤32周组33例,并以26例符合光疗条件的高未结合胆红素血症足月儿为对照组,给予24 h连续光疗。用放射免疫法测定ET,用硝酸还原酶法测定NO。在光疗期间定期监测心率、呼吸(包括呼吸暂停)、平均动脉压。结果胎龄≤32周组:光疗24 h与光疗前比较血浆ET值明显升高(P<0.05);光疗12和24 h较光疗前血清NO值升高具有统计学意义(P<0.05);光疗24 h与光疗前血NO/ET比值的升高也具有统计学意义(P<0.05)。胎龄>32周组:仅光疗24 h较光疗前血清NO值升高有统计学意义(P<0.05)。胎龄≤32周组光疗24 h较光疗前心率增快、平均动脉压下降均有统计学意义(P<0.05),光疗24 h血NO/ET比值与平均动脉压呈负相关性。胎龄≤32周组较胎龄>32周组和足月组光疗中呼吸暂停发生例次数明显增多。结论光疗对早产儿尤其小胎龄早产儿血ET、NO影响明显,可能会导致血流动力学改变,应予关注。     

The effect of phototherapy on cerebral blood flow velocity in preterm infants

Cerebral blood flow velocity was studied with two-dimensional/pulsed Doppler ultrasound before, during and after discontinuation of phototherapy in 22 preterm infants (gestational age ≤32 weeks), who were treated for a minimum of 12h with blue-light phototherapy for non-haemolytic hyperbilirubinaemia. Before the cerebral blood flow velocity measurements, patency of the ductus arteriosus was diagnosed by Doppler echocardiography. All infants had normal brain ultrasound scans. Mean cerebral blood flow velocity increased significantly after initiation of phototherapy in all infants. Only in “healthy” (non-ventilated) infants did cerebral blood flow velocity return to pre-phototherapy values (baseline) after discontinuation of phototherapy, whereas in “unhealthy” (ventilated) infants cerebral blood flow velocity did not return to baseline. In 10 infants the ductus arteriosus reopened during phototherapy. In those infants, mean cerebral blood flow velocity returned to pre-phototherapy values after 2h of phototherapy prior to its discontinuation.