Biomedical subjects

R Sahni

Publications and source records attributed to R Sahni.

At least 19 recordsLinked to original sources

PubMed2005

Sleeping position and electrocortical activity in low birthweight infants.

OBJECTIVE: To evaluate the effects of prone and supine sleeping positions on electrocortical activity during active (AS) and quiet (QS) sleep in low birthweight infants. DESIGN: Randomised/crossover study. SETTING: Infant Physiology Laboratory at Children's Hospital of New York. PATIENTS: Sixty three healthy, growing, low birthweight (birth weight 795-1600 g) infants, 26-37 weeks gestational age. INTERVENTIONS: Six hour continuous two channel electrocortical recordings, together with minute by minute behavioural state assignment, were performed. The infants were randomly assigned to prone or supine position during the first three hours, and positions were reversed during the second three hours. OUTCOME MEASURES AND RESULTS: Fast Fourier transforms of electroencephalograms (EEGs) were performed each minute and the total EEG power (TP), spectral edge frequency (SEF), absolute (AP) and relative (RP) powers in five frequency bands (0.01-1.0 Hz, 1-4 Hz, 4-8 Hz, 8-12 Hz, 12-24 Hz) were computed. Mean values for TP, SEF, AP, and RP in the five frequency bands in the prone and supine positions during AS and QS were then compared. In the prone sleeping position, during AS, infants showed significantly lower TP, decreased AP in frequency bands 0.01-1.0 Hz, 4-8 Hz, 8-12 Hz, 12-24 Hz, increased RP in 1-4 Hz, and a decrease in SEF. Similar trends were observed during QS, although they did not reach statistical significance. CONCLUSIONS: The prone sleeping position promotes a shift in EEG activity towards slower frequencies. These changes in electrocortical activity may be related to mechanisms associated with decreased arousal in the prone position and, in turn, increased risk of sudden infant death syndrome.

Cerebral Cortex↗

PubMed2003

Motion resistant pulse oximetry in neonates.

BACKGROUND: Pulse oximetry is widely used in neonates. However, its reliability is often affected by motion artefact. Clinicians confronted with questionable oxygen saturation (SpO(2)) values often estimate the reliability by correlating heart rate (HR) obtained with the oximeter with that obtained by electrocardiogram. OBJECTIVE: To compare the effects of motion on SpO(2) and HR measurements made with Masimo signal extraction technology and those made with a Nellcor N-200. DESIGN: Continuous pulse oximetry and HR monitoring were performed in 15 healthy, term infants (mean (SD) birth weight 3408 (458) g) undergoing circumcision, using Masimo and Nellcor pulse oximeters and a standard HR monitor (Hewlett-Packard). Simultaneous minute by minute behavioural activity codes were also assigned. Baseline data were collected for 10 minutes when the infant was quietly asleep and then continued during and after circumcision for a total duration of one hour. The oximeter HR and SpO(2) values were compared and related to HR values obtained by ECG during all three periods. The effect of behavioural activity on SpO(2) and HR was also evaluated. RESULTS: When compared with results obtained with the Nellcor, the mean SpO(2) and HR were higher and the incidence of artefact lower with the Masimo during all three periods. Masimo HR more accurately predicted HR obtained with a standard monitor, with lower residual error. SpO(2) and HR values obtained with the Nellcor were lower and more variable during all behavioural states, especially crying, when excessive motion artefact was most likely. CONCLUSIONS: The data suggest that Masimo signal extraction technology may offer improvement in pulse oximetry performance, particularly in clinical situations in which extreme motion artefacts are likely.

Artifacts↗

PubMed2002

Frequency of perinatal transfer by day of the week and holidays.

OBJECTIVE: To describe the pattern of obstetric transfers to a rural tertiary center relative to weekends and holidays. METHODS: A 2-year retrospective cohort study. RESULTS: A total of 903 patients were received in transfer over the study period. Tuesday was the most frequent day (17.4%) for transfer and Sunday was the least frequent day (9.2%). Friday was the most frequent day for transfer of patients who did not deliver (18.6%) and Sunday the least frequent day for transfer (7.6%). Subset analysis by delivery status found no statistical difference in the frequency of transfer by delivery status and day of the week (p = 0.28). Tuesday had the highest mean at 1.51 +/- 1.13 and Sunday had the lowest mean at 0.8 +/- 0.89. No difference in transfer volume by day of the week was observed by ANOVA (p = 0.25). The number of transfers occurring around the 7 days surrounding the six major holidays averaged 7.67 +/- 3.63, which did not differ significantly from the weekly average of 8.59 +/- 2.74 (p = 0.29). CONCLUSION: There is no apparent bias to transfer of patients based on the day of the week or holidays. Individual assessment by regional centers may assist in planning for staffing of transport services and resources.

Adult↗

PubMed2001

Effects of quality of energy on substrate oxidation in enterally fed, low-birth-weight infants.

BACKGROUND: Carbohydrate and fat may differ in their ability to support energy-requiring physiologic processes, such as protein synthesis and growth. If so, varying the constituents of infant formula might be therapeutically advantageous. OBJECTIVE: We tested the hypothesis that low-birth-weight infants fed a diet containing 65% of nonprotein energy as carbohydrate oxidize relatively more carbohydrate and relatively less protein than do infants fed an isoenergetic, isonitrogenous diet containing 35% of nonprotein energy as carbohydrate. DESIGN: Sixty-two low-birth-weight infants weighing from 750 to 1600 g at birth were assigned randomly and blindly to receive 1 of 5 formulas that differed only in the quantity and quality of nonprotein energy. Formula containing 544 kJ x kg(-1) x d(-1) with either 50%, 35%, or 65% of nonprotein energy as carbohydrate was administered to control subjects, group 1, and group 2, respectively. Groups 3 and 4 received gross energy intakes of 648 kJ x kg(-1) x d(-1) with 35% and 65% of nonprotein energy as carbohydrate. Protein intake was targeted at 4 g x kg(-1) x d(-1). Substrate oxidation was estimated from biweekly, 6-h measurements of gas exchange and 24-h urinary nitrogen excretion. RESULTS: Carbohydrate oxidation was positively (r = 0.71, P < 0.0001) and fat oxidation was negatively (r = -0.46, P < 0.001) correlated with carbohydrate intake. Protein oxidation was negatively correlated with carbohydrate oxidation (r = -0.42, P < 0.001). Fat oxidation was not correlated with protein oxidation. Protein oxidation was less in infants receiving 65% of nonprotein energy as carbohydrate than in groups receiving 35% nonprotein energy as carbohydrate. CONCLUSION: These data support the hypothesis that energy supplied as carbohydrate is more effective than energy supplied as fat in sparing protein oxidation in enterally fed low-birth-weight infants.

Carbon Dioxide↗

PubMed2001

Effects of quality of energy intake on growth and metabolic response of enterally fed low-birth-weight infants.

Carbohydrate and fat may vary in their ability to support protein accretion and growth. If so, variations in the source of nonprotein energy might be used to therapeutic advantage in enterally fed low-birth-weight infants. To test the hypothesis that high-carbohydrate diets are more effective than isocaloric high-fat diets in promoting growth and protein accretion, low-birth-weight infants weighing 750-1600 g at birth were randomized in a double blind study to receive one of five formulas differing only in the quantity and quality of nonprotein energy. Groups 1, 2, and control received 130 kcal x kg(-1) x d(-1) with 35, 65, and 50% of the nonprotein energy as carbohydrate. Groups 3 and 4 received energy intake of 155 kcal x kg(-1) x d(-1) with 35 and 65% of the nonprotein energy as carbohydrate. Protein intake of all groups was 4 g x kg(-1) x d(-1). Growth and metabolic responses were followed weekly, and macronutrient balances including 6-h indirect calorimetry were performed biweekly. Greater rates of weight gain and nitrogen retention were observed at high-carbohydrate intake compared with high-fat intake at both gross energy intakes. Greater rates of energy storage and an increase in skinfold thickness were observed in group 4 (high-energy high-carbohydrate diet) despite higher rates of energy expenditure. These data support the hypothesis that at isocaloric intakes, carbohydrate is more effective than fat in enhancing growth and protein accretion in enterally fed low-birth-weight infants. However, a diet with high-energy and high-carbohydrate content also results in increased fat deposition.

Body Weight↗

PubMed2000

Maturational changes in heart rate and heart rate variability in low birth weight infants.

To provide insight into the maturation of neural mechanisms responsible for variability in heart rate during quiet and active sleep, 6-hour continuous electrocardiographic recordings and simultaneous minute-by-minute behavioral activity state assignments were performed in 61 healthy, growing low birth weight infants. The infants weighed 795-1600 g at birth and ranged between 31-38 weeks in postconceptional age. During this age interval there was a decrease in heart rate during quiet sleep and an increase in both time domain and frequency domain measures of the variability in cardiac interbeat intervals. In quiet sleep, global variability, measured as SD of R-R intervals, increased in relation to age, as did higher frequency variability, measured as the square root of the mean of squared successive differences in R-R intervals. Developmental changes in the 0.5-2.0 Hz spectral power band of RR-interval variability, another measure of high frequency variability, paralleled the changes seen in the time domain measure. Evaluation of patterns of changes in the magnitude and direction of successive interbeat intervals provided evidence that the incidence of sustained accelerations or decelerations increased whereas the incidence of no change in consecutive RR-intervals decreased as infants matured. Among the various measures of heart rate variability, the incidence of sustained change and no change in successive interbeat intervals were most closely related to postconceptional age in both sleep states. The overall decrease in heart rate, increase in heart rate variability, and increase in the pattern of changes in interbeat interval with postconceptional age are consistent with the maturation of the autonomic cardio-regulatory activity from 31-38 weeks age.

Electrocardiography↗

PubMed2000

Randomised controlled trial of thiopental for intubation in neonates.

AIMS: To determine the effects of premedication with thiopental on heart rate, blood pressure, and oxygen saturation during semi-elective nasotracheal intubation in neonates. METHODS: A randomised, placebo controlled, non-blinded study design was used to study 30 neonates (mean birthweight 3.27 kg) requiring semi-elective nasotracheal intubation. The babies were randomly allocated to receive either 6 mg/kg of thiopental (study group) or an equivalent volume of physiological saline (control group) one minute before the start of the procedure. Six infants were intubated primarily and 24 were changed from orotracheal to a nasotracheal tube. The electrocardiogram, arterial pressure wave, and transcutaneous oxygen saturation were recorded continuously 10 minutes before, during, and 20 minutes after intubation. Minute by minute measurements of heart rate, heart rate variability, mean blood pressure (MBP) and transcutaneous oxygen saturation (SpO(2)) were computed. The differences for all of these between the baseline measurements and those made during and after intubation were determined. Differences in the measurements made in the study and the control groups were compared using Student's t test. RESULTS: During intubation, heart rate increased to a greater degree (12.0 vs -0.5 beats per minute, p < 0.03) and MBP increased to a lesser degree (-2.9 vs 4.4 mm Hg; p < 0.002) in the infants who were premedicated with thiopental. After intubation only the changes in MBP differed significantly between the two groups (-3.8 vs 4.6 mm Hg; p < 0.001). There were no significant changes in the oxygen saturation between the two groups during or after intubation. The time taken for intubation was significantly shorter in the study group (p < 0.04). CONCLUSIONS: The heart rate and blood pressure of infants who are premedicated with thiopental are maintained nearer to baseline values than those of similar infants who receive no premedication. Whether this lessening of the acute drop in the heart rate and increase in blood pressure typically seen during intubation of unmedicated infants is associated with long term advantages to the infants remains to be determined.

Birth Weight↗

PubMed1999

Body position, sleep states, and cardiorespiratory activity in developing low birth weight infants.

The objective of this study was to determine the effects of body position (supine vs prone) on cardiorespiratory activity during quiet and active sleep in growing low birth weight (LBW) infants. The effect of postconceptional age on cardiorespiratory activity in the two positions was also evaluated. Fifty-one healthy, growing, appropriate for gestational age LBW infants (795-1600 g), ranging from 26-37 weeks in gestational age, were evaluated. All subjects were enrolled in an ongoing study of the effects of quality of dietary energy on the rate and composition of weight gain. Infants were randomly assigned to the supine or prone position for the first 3 h of the 6-h studies; the position was reversed for the second 3 h. Continuous recordings of cardiorespiratory activity were performed along with simultaneous minute by minute assignment of behavioral sleep state. Measurements of heart rate (HR), heart period variability (RR-SD), respiratory rate (f), and respiratory variability (fSD) were made each minute. Low birth weight infants had higher HR and f and lower RR-SD and fSD in the prone position compared to the supine position, during both quiet and active sleep. With increasing postconceptional age, positional differences in HR increased during quiet sleep and differences in RR-SD increased during both sleep states. These data demonstrate systematic differences in cardiorespiratory control related to body position during sleep. We speculate that such positional differences are due to variations in autonomic control, and may, in turn, contribute to variations in susceptibility to sudden infant death syndrome.

Aging↗

PubMed1999

Postural differences in cardiac dynamics during quiet and active sleep in low birthweight infants.

To study the effects of body position (supine versus prone) on changes in cardiac inter-beat interval during quiet and active sleep, 6-h continuous electrocardiographic recordings and simultaneous minute-by-minute behavioural activity state assignments were made in 61 healthy, growing, low birthweight infants. The infants weighed 795-1600 g at birth and ranged between 30-38 wk in postconceptual age. Infants were randomly assigned to the supine or prone position for the first 3 h of each study; the position was reversed for the second 3 h. Higher heart rates and lower time and frequency domain measures of inter-beat interval variability were observed in the prone position as compared to the supine position, during both quiet and active sleep. In addition, an analysis of consecutive increases and decreases in the instantaneous heart rate revealed a lower incidence of sustained accelerations or decelerations in the prone position. Although consistent findings concerning inter-beat interval variability and sleeping position were obtained from all analytic techniques, the differences derived from analysis of consecutive inter-beat changes were the most robust. These differences in multiple measures of cardiac rate and rhythm between prone and supine positions suggest that autonomic control of the heart is altered by body position, the net effect on heart rate being increased sympathetic dominance.

Autonomic Nervous System↗

PubMed1998

Effects of sleeping position and time after feeding on the organization of sleep/wake states in prematurely born infants.

Epidemiologic studies provide strong evidence for the conclusion that sleeping in the prone position places infants at greater risk for sudden infant death syndrome (SIDS). Prior studies in newborn infants found that in the prone sleeping position there is less time awake and more quiet sleep, but little change in the amount of active sleep. To determine whether the effects of sleeping position on state distribution vary with time after feeding, we studied prematurely born infants in both the prone and supine sleeping positions. Sleep states were recorded each minute during interfeed intervals. Results demonstrate expected effects of sleep position on state distribution: prone sleeping is associated with a 79% increase in quiet sleep and a 71% decrease in time awake. While the decreases in time awake are seen throughout the interfeed interval, increases in quiet sleep in the prone position are found only within the first hour and again near the end of the interfeed interval. These results are consistent with the hypothesis that prone sleeping could increase risk for SIDS by altering the organization of sleep, and that time after feeding may play an important role in the expression of these effects.

Analysis of Variance↗

PubMed1998

Spontaneous correction of the malpositioned percutaneous central venous line in infants.

Malpositioning of the percutaneously placed central venous line (PCVL) or percutaneously inserted central catheter (PICC) in infants is not a rare occurrence. It has been occasionally observed that these lines spontaneously correct themselves. This prospective study was done to study the incidence of malposition and spontaneous correction. Using a modification of the standard method, 187 catheters were placed with 98.9 % success. Seven of these were initially malpositioned. All seven corrected themselves within a day when left in and used as a peripheral intravenous line. In many centers malpositioned catheters are taken out and replaced, which imposes great stress on the critically ill infant. Our study suggests that to avoid this stress the catheter should be left in place, since spontaneous correction may occur.

Catheterization, Central Venous↗

PubMed1997

A novel quantitative measure of Tracé-alternant EEG activity and its association with sleep states of preterm infants.

This study describes the application of a novel quantitative method for classifying patterns of EEG activity that are associated with the predominant sleep-states of newborn infants. Periods in which there are bursts of high-voltage slow wave activity in the EEG that alternate with periods of low-voltage activity are termed Tracé-alternant. During active or REM sleep. Tracé-alternant is absent and EEG activity is characterized by a variable mixture of frequencies including intermittent high frequency (10-20 Hz) activity superimposed on slower frequencies. Results show that an analytic method previously developed in fetal baboons for identifying EEG segments with and without Tracé-alternant successfully distinguishes homologous patterns of EEG activity in preterm infants. This method provides an excellent objective approach for monitoring changes in EEG patterns that are coincident with behaviorally defined sleep states.

Animals↗

PubMed1997

Sleep state, cardiorespiratory and electrocortical activity in infants with transposition of great vessels.

OBJECTIVES: Sleep states and physiological changes during sleep may be useful in assessing brain function. We hypothesized that infants with transposition of great vessels (TGV) exhibit recognizable states of sleep under conditions of isocapnic hypoxemia. Also, we speculated that early correction of hypoxemia may result in significant changes in the physiological characteristics of quiet and active sleep. METHODS: Six-hour continuous cardiorespiratory and electrocortical recordings were performed in five term infants with TGV, pre- and postoperatively along with simultaneous minute by minute behavioral sleep state assignment. Data were sorted for sleep states and percent sleep time for each state was computed. Measurements of state-dependent variables, i.e., heart rate (HR), heart rate variability (HRSD), respiratory frequency (f), variability in respiratory frequency (fSD), and spectral properties of the EEG during quiet and active sleep were compared for both pre- and postoperative periods. RESULTS: All infants showed significant differences in state-dependent variables between quiet and active sleep, both during preoperative (mean O2 saturation = 80.9 +/- 2.8) and postoperative (mean O2 saturation = 92.8 +/- 0.5) periods. As compared to preoperative period, postoperatively during quiet sleep, HR and HRSD were lower, and EEG power was greater; and during active sleep, HR, HRSD, and fSD decreased and EEG power increased. Also, in the postoperative period % quiet sleep increased and % active sleep decreased. CONCLUSIONS: Under conditions of isocapnic hypoxemia infants with TGV vessels exhibit clearly recognizable states of sleep. Correction of hypoxemia is associated with significant changes in state-dependent variables both during quiet and active sleep.

Electroencephalography↗

PubMed1997

Diet and infant behavior.

We studied 142 preterm infants (mean gestation 31 weeks, mean birthweight 1364 g) fed prospectively varied protein and energy intakes. Infants were grouped as either slow or rapid growers based on rate of weight gain. Rapid growers had increased heart rates (166 vs 160 beats/min), respiratory rates (55.7 vs 53.9 bpm), energy expenditure (64.8 vs 61.6 kcal kg(-1) day(-1)), urinary C-peptide levels (1.59 vs 0.79 ng ml(-1)) and time in active sleep (78.0 vs 75.2%), and decreased spectral edge frequency in the electroencephalogram (2.96 vs 4.45 Hz) compared to slow growers. We conclude that preterm infants growing at varying rates manifest physiological and behavioral differences, and that these patterns may reflect altered autonomic balance.

Diet↗

PubMed1997

Weaning strategy with inhaled nitric oxide treatment in persistent pulmonary hypertension of the newborn.

AIM: To determine if infants who had become dependent on inhaled nitric oxide treatment could be successfully weaned off it if FIO2 was increased briefly during withdrawal. METHODS: Sixteen infants admitted for conditions associated with increased pulmonary vascular resistance responded well to inhaled nitric oxide treatment with a significant increase in PaO2 (maximum inhaled nitric oxide given 25 ppm). Weaning from inhaled nitric oxide in 5 ppm decrements was initiated once the FIO2 requirement was less than 0.5. When patients were stable on 5 ppm of inhaled nitric oxide, the gas was then discontinued. If a patient showed inhaled nitric oxide dependence-that is, oxygen saturation fell by more than 10% or below 85%-inhaled nitric oxide was reinstated at 5 ppm and the patient allowed to stabilise for 30 minutes. At this time, FIO2 was increased by 0.40 and weaning from inhaled nitric oxide was attempted again. RESULTS: Nine infants were successfully weaned on the first attempt. The seven infants who failed the initial trial were all successfully weaned following the increase in FIO2. After successful weaning, FIO2 was returned to the pre-weaning level in mean 148(SD 51) minutes and inhaled nitric oxide was never reinstated. CONCLUSION: Infants showing inhaled nitric oxide dependency can be successfully weaned by increasing FIO2 transiently.

Administration, Inhalation↗

PubMed1995

Methodological issues in coding sleep states in immature infants.

Thirty-five healthy, premature infants, ranging from 30-39 weeks postconceptional age, were observed continuously for 6 to 24 hr. Behavioral state and electroencephalographic patterns were coded for each minute. Using these data, three questions regarding coding of states of sleep were addressed: What is the concordance between behavioral codes and specific EEG patterns? Does the concordance between behavioral codes and EEG patterns change with postconceptional age? What range of error can be expected when observation periods shorter than 24-hr are used to estimate the daily distribution of quiet sleep (QS) and active sleep (AS)? With behavioral codes as the standard, concordances of EEG patterns for QS and AS were 72.5 and 92.1% respectively. With EEG patterns as the standard, behavioral codes for QS and AS agreed 83.0 and 88.9%. Agreement between behavioral codes and EEG patterns for QS increased with age. Finally, variation in estimates of the daily distribution of QS and AS decreased dramatically as the length of observation increased from 3 to 24 hr.

Arousal↗

PubMed1995

Congenital diaphragmatic hernia: survival treated with very delayed surgery, spontaneous respiration, and no chest tube.

This report suggests that stabilization of the intrauterine to extrauterine transitional circulation combined with a respiratory care strategy that avoids pulmonary overdistension, takes advantage of inherent biological cardiorespiratory mechanics, and very delayed surgery for congenital diaphragmatic hernia results in improved survival and decreases the need for extracorporeal membrane oxygenation (ECMO). This retrospective review of a 10-year experience in which the respiratory care strategy, ECMO availability, and technique of surgical repair remained essentially constant describes the evolution of this method of management of congenital diaphragmatic hernia.

Chest Tubes↗

PubMed1995

Preoperative cardiorespiratory trends in infants with congenital diaphragmatic hernia.

The objective of this study was to determine the cardiovascular and pulmonary adaptations of infants with congenital diaphragmatic hernia (CDH) from birth until delayed surgery through the use of continuous monitoring. Continuous cardiovascular (HR, heart rate variability [HR-SD], BP, blood pressure variability [BP-SD], and oxygen saturation) and ventilatory (minute volume, airway pressure, and effective compliance) measurements were made on-line, using a computerized whole-body plethysmograph-incubator (Vital-trends, VT1000), in nine ventilated infants with CDH. Data collection commenced at birth and continued until surgery. Minute mean values for each variable were recorded. Hourly means were computed from the minute means, averaged across infants each hour over the first 50 hours of life, and regressed against postnatal age. Results showed a significant increase in BP (P < .01), BP-SD (P < .05), HR-SD (P < .04), and pH (P < .02) versus postnatal age, and a decrease in PaCO2 (P < .04), FIO2 (P < .001), Alveolar-arterial oxygen gradient (P < .003), and oxygenation index (P < .002). Infants with CDH show cardiopulmonary trends over the first 2 days of life that are qualitatively similar to those of normal newborn infants. Deviation from these idealized patterns may identify an infant who is not responding satisfactorily to the given therapy and who may require alternative treatment modalities.

Adaptation, Physiological↗