Effects of O2 on the ventilatory response to CO2 in preterm infants

1975 ◽  
Vol 39 (6) ◽  
pp. 896-899 ◽  
Author(s):  
H. Rigatto ◽  
R. De La Torre Verduzco ◽  
D. B. Gates
Keyword(s):  
Preterm Infants ◽  
Gestational Age ◽  
Ventilatory Response ◽  
Respiratory Center ◽  
Response Curves ◽  
Co2 Response ◽  
O2 Concentration ◽  
The Mean ◽  
Ventilatory Response To Co2

To measure the effects of O2 on the ventilatory response to CO2 in preterm infants, we studied eight babies (birth wt 1–2 kg; gestational age 32–36 wk) 10 times during the first 11 days of life. After breathing 21% O2 for 3 min, they were given 15%, 21%, 40%, or 100% O2 for 4 min and then 2% CO2 plus the various concentrations of O2 for 4 min each. The mean slopes of the CO2 response curves were 0.013, 0.027, 0.034, and 0.056 1/(min-kg-mmHg PACO2) with 15%, 21%, 40%, and 100% inspired O2, respectively. Thus, the more hypoxic the infant, the flatter was the response to CO2. These findings suggest that in preterm infants 1) the response to inhaled CO2 is the reverse of that seen in adult man where the higher the inspired O2 concentration, the flatter the response, and 2) the respiratory center is depressed during hypoxia.

Effect of Continuous Positive Airway Pressure on the Ventilatory Response to CO2 in Preterm Infants

PEDIATRICS ◽  
1983 ◽  
Vol 71 (4) ◽  
pp. 634-638
Author(s):  
Manuel Durand ◽  
Ellen McCann ◽  
June P. Brady
Keyword(s):  
Tidal Volume ◽  
Preterm Infants ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Co2 Response ◽  
Expiratory Time ◽  
Ventilatory Response To Co2

The effect of continuous positive airway pressure (CPAP) on the ventilatory response to CO2 in newborn infants is unknown. The CO2 response to 4% CO2 in air was studied in nine preterm infants without lung disease before and during administration of CPAP (4 to 5 cm H2O) delivered by face mask. Minute ventilation, tidal volume, respiratory frequency, and end-tidal Pco2 were measured, and the slope and intercept of the CO2 response were calculated. Respiratory pattern and changes in oxygenation were also analyzed by measuring inspiratory and expiratory time, mean inspiratory flow, mean expiratory flow, effective respiratory timing, endtidal Po2, and transcutaneous Po2. CPAP significantly decreased minute ventilation from 278.7 to 197.6 mL/mm/kg (P < .001). Tidal volume and respiratory frequency were also significantly decreased. The slope of the CO2 response during CPAP was not significantly different from the slope before CPAP (36 v 33 mL/min/kg/mm Hg, P > .1), but the intercept was shifted to the right (P < .001). The decrease in respiratory frequency was primarily due to a prolongation of expiratory time (P < .05). In addition, transcutaneous Po2 increased during administration of CPAP (P < .001). These findings indicate that: (1) CPAP significantly decreases ventilation in preterm infants without lung disease, affecting both tidal volume and respiratory frequency; (2) CPAP does not appreciably alter the ventilatory response to CO2; (3) the changes in respiratory frequency are primarily accounted for by a prolongation of expiratory time; (4) CPAP improves oxygenation.

Adaptations to diving in the harbor seal— gas exchange and ventilatory response to CO2

1963 ◽  
Vol 205 (6) ◽  
pp. 1175-1177 ◽  
Author(s):  
Eugene D. Robin ◽  
H. Victor Murdaugh ◽  
William Pyron ◽  
Edgar Weiss ◽  
Peter Soteres
Keyword(s):  
Gas Exchange ◽  
Ventilatory Response ◽  
Harbor Seal ◽  
Phoca Vitulina ◽  
Pulmonary Gas Exchange ◽  
Respiratory Center ◽  
Harbor Seals ◽  
Response Curves ◽  
Ventilatory Response To Co2

Pulmonary gas exchange and the ventilatory response to CO2 were measured in six female harbor seals, Phoca vitulina. Mean Paco2 (48 ± 6 mm Hg) is higher in the seal and mean Pao2 (88 ± 9 mm Hg) is lower than the corresponding value in man. The seal shows a depressed ventilatory response to CO2 both in terms of slope and intercept of CO2 response curves. The depressed respiratory center sensitivity to CO2 presumably is an adaptative mechanism permitting prolonged diving in this species.

Effect of Maternal Race on Outcome of Preterm Infants in the Military

PEDIATRICS ◽  
1993 ◽  
Vol 91 (3) ◽  
pp. 572-577
Author(s):  
David N. Greenberg ◽  
Bradley A. Yoder ◽  
Reese H. Clark ◽  
Clifford A. Butzin ◽  
Donald M. Null
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Preterm Infants ◽  
Gestational Age ◽  
Military Hospital ◽  
Free Access ◽  
Multiple Gestation ◽  
Entire Study ◽  
The Mean ◽  
Maternal Race

Previous studies suggest that low birth weight black infants have less morbidity and birth-weight-specific mortality during the perinatal period than low birth weight white infants. We studied the effect of maternal race on outcome in preterm infants born at a military hospital that offers free access to obstetric and neonatal care. Between January 1, 1986, and December 31, 1991, data were prospectively collected on all 667 infants delivered at Wilford Hall USAF Medical Center with an estimated gestational age of less than 35 weeks. Three hundred ninety-two white infants and 165 black infants were included in the data analysis. The mean (±SD) birth weight was 1701 ± 65 g for white infants and 1462 ± 66 g for black infants. The mean estimated gestational age was 31.0 ± 3.2 weeks for white infants and 29.9 ± 3.8 weeks for black infants. Preeclampsia was more frequent in black mothers than in white mothers for the entire study population (21% vs 14%), but the birth weight differential between races remained after correction for preeclampsia. There were no significant differences between races in stillbirths, gender, maternal age, maternal transfer status, number of prenatal visits, or percentages of mothers with small-for-gestational-age infants, multiple-gestation infants, prolonged rupture of membranes, or initial prenatal visit during the first trimester. Intraventricular hemorrhage was more frequent in white infants at 27 through 29 weeks estimated gestational age (50% vs 13%). There were no significant differences between the two groups in survival or in the occurrence of severe infraventricular hemorrhage or bronchopulmonary dysplasia. It is concluded that preterm black infants are smaller than preterm white infants when matched for gestational age despite essentially equal utilization of prenatal care. However, maternal race has little direct effect on the survival of liveborn preterm infants in this population.

Effect of baseline oxygenation on the ventilatory response to inhaled 100% oxygen in preterm infants

1995 ◽  
Vol 79 (6) ◽  
pp. 2101-2105 ◽  
Author(s):  
A. Z. Haider ◽  
V. Rehan ◽  
S. Al-Saedi ◽  
R. Alvaro ◽  
K. Kwiatkowski ◽  
...  
Keyword(s):  
Preterm Infants ◽  
Ventilatory Response ◽  
Recovery Period ◽  
Control Period ◽  
Periodic Breathing ◽  
Quiet Sleep ◽  
Peripheral Chemoreceptor ◽  
Lower Baseline ◽  
O2 Concentration ◽  
Flow Through

We tested the hypothesis that the immediate (< 1 min) ventilatory response to 100% O2 in preterm infants, a test of peripheral chemoreceptor activity characterized by a decrease in ventilation due to apnea, is more pronounced at lower baseline O2 concentrations. We studied 12 healthy preterm infants [birth weight 1,425 +/- 103 (SE) g; study weight 1,670 +/- 93 g; gestational age 30 +/- 1 wk; postnatal age 27 +/- 7 days] during quiet sleep. The infants inhaled 15, 21, 25, 30, 35, 40, and 45% O2 for 5 min in a randomized manner (control period), followed by 100% O2 for 2 min, and then the same initial O2 concentration again for 2 min (recovery period). A nose piece and a flow-through system were used to measure ventilation. The immediate decrease in ventilation with 100% O2 was 46% on 15% O2, 24% on 21% O2, 11% on 25% O2, 8% on 30% O2, 12% on 35% O2, and 8% on 40% O2; there was no decrease on 45% O2 (P < 0.01). The corresponding mean duration of apnea was 29 s during 15% O2, 18 s during 21% O2, 8 s during 25% O2, 9 s during 30 and 35% O2, and 3 s during 40% O2; only one infant developed a 5-s apnea during 45% O2 (P < 0.001). The findings suggest that 1) the ventilatory decrease in response to 100% O2 is dependent on the baseline oxygenation, being more pronounced the lower the baseline O2 concentration; and 2) this ventilatory decrease is entirely related to more prolonged apneas observed with lower baseline O2 concentrations. We speculate that the peripheral chemoreceptors, being so active in the small preterm infant with relatively low arterial PO2, are highly susceptible to changes in PO2, and this makes them prone to irregular or periodic breathing, especially during sleep.

Respiratory adaptation to hyperthyroidism

1960 ◽  
Vol 15 (6) ◽  
pp. 1107-1112 ◽  
Author(s):  
H. Valtin ◽  
S. M. Tenney
Keyword(s):  
Ventilatory Response ◽  
Human Subjects ◽  
Respiratory Center ◽  
Whole Body ◽  
Response Curves ◽  
Direct Stimulation ◽  
Enhanced Sensitivity ◽  
Whole Body Metabolism ◽  
Sensitivity Changes ◽  
Respiratory Stimulation

In order to test the general postulate that increases in whole body metabolism are accompanied by net respiratory stimulation, respiratory adaptation to thyrotoxicosis was studied in clinical hyperthyroidism and in experimental hyperthyroidism in man and the rat. It was found that in contrast to other hypermetabolic states such as fever and salicylate and dinitrophenol administration, alveolar CO2 tension rises in hyperthyroidism, reflecting a proportionately greater increase in metabolism (CO2 production) than in alveolar ventilation. Ventilatory response curves in three human subjects with experimentally induced hyperthyroidism showed no increase in sensitivity (Deltaa/DeltaPaCOCO2 of the respiratory center to CO2. This finding differs from that in salicylism and dinitrophenol administration in which enhanced sensitivity is manifest. It is concluded that the respiratory stimulation resulting from increased CO2 production is modified by factors such as changes in respiratory center sensitivity, changes in cerebral blood flow and direct stimulation of the respiratory center, so that the net respiratory adjustment cannot be predicted from a knowledge of the increase in metabolism alone. Submitted on April 7, 1960

Effects of CO2 on immediate ventilatory response to O2 in preterm infants

1976 ◽  
Vol 41 (5) ◽  
pp. 609-611 ◽  
Author(s):  
S. Albersheim ◽  
R. Boychuk ◽  
M. M. Seshia ◽  
D. Cates ◽  
H. Rigatto
Keyword(s):  
Preterm Infants ◽  
Ventilatory Response ◽  
Background Concentrations ◽  
Peripheral Chemoreceptor ◽  
Co2 Response ◽  
Peripheral Chemoreceptors ◽  
Paradoxical Response

We wanted to know wheter the paradoxical response to CO2 under various background concentrations of O2 in preterm infants was mediated at the peripheral chemoreceptors. In five preterm infants we estimated peripheral chemoreceptor activity using the immediate change in ventilation (first 30 s) when 15%, 40%, 60%, or 100% O2 was substituted for 21% O2. Potentiation between O2 and CO2 was assessed by comparing the response with and without 4% CO2. CO2 enhanced the immediate hyperventilation with hypoxia (P less than 0.005) and reduced the immediate hypoventilation with hyperoxia (P less than 0.025 for 40% O2). This effect of CO2 increased from .00% to 15% O2 (P lessthan 0.05). These findings suggest: 1) CO2 interacts with O2 at the peripheral chemoreceptor level, and 2) because this interaction is more pronouncedwith hypoxia, the flatter CO2 response we observed with hypoxia was probably not mediated through the peripheral chemoreceptors and is likely to be central in origin.

scholarly journals Influence of Maternal Preeclampsia on Neurodevelopmental Outcomes of Preterm Infants

2018 ◽  
Vol 24 (2) ◽  
pp. 99
Author(s):  
Halil Degirmencioglu ◽  
Birgul Say ◽  
Zeynep Ustunyurt ◽  
Serife Suna Oguz
Keyword(s):  
Cerebral Palsy ◽  
Preterm Infants ◽  
Gestational Age ◽  
Infant Development ◽  
Neurodevelopmental Outcome ◽  
Control Group ◽  
Neurodevelopmental Outcomes ◽  
Term Outcome ◽  
Long Term Outcome ◽  
The Mean

<p><strong>Objective:</strong> The aim of this study was to determine the neurodevelopmental outcome of preterm infants born to mothers with preeclampsia and to compare them with preterm controls.</p><p><strong>Study design:</strong> This was a retrospective, observational study in a large, tertiary, neonatal intensive care unit. Neurodevelopmental evaluations using Bayley Scales of Infant Development II were performed in 226 two-year-old infants with birth weight ≤1500 g and gestational age ≤32 weeks who were born to mothers with preeclampsia and in 493 infants who were born after normotensive pregnancies, matched for gestational age and gender.</p><p><strong>Results:</strong> The mean gestational ages of the infants in the preeclampsia and control groups were 29.9±2.3 weeks and 28.7±4.1 weeks, respectively (p&lt;0.001). A total of 372 infants with a mean age of 19.2±3.2 months were assessed for long-term outcome. The mean mental developmental index score was significantly higher, and the percentage of infants with cerebral palsy was significantly lower, in the preeclampsia group compared with the control group (p=0.03 and p=0.02, respectively). However, no overall significant differences in neurodevelopmental impairment rates were found between the two groups (p=0.08).</p><p><strong>Conclusion:</strong> Maternal preeclampsia seems to be a protector factor for the development of cerebral palsy in preterm infants.</p>

scholarly journals INVESTIGATING THE PHOTOTHERAPY THRESHOLDS IN PRETERM INFANTS

2018 ◽  
Vol 23 (suppl_1) ◽  
pp. e28-e28 ◽  
Author(s):  
Thivia Jegathesan ◽  
Michael Sgro ◽  
Vibhuti Shah ◽  
Aidan Campbell ◽  
Douglas Campbell
Keyword(s):  
Preterm Infants ◽  
Gestational Age ◽  
Chart Review ◽  
Age Groups ◽  
Retrospective Chart Review ◽  
Term Infants ◽  
Treatment Thresholds ◽  
Weight Outcomes ◽  
The Mean ◽  
Current Guidelines

Abstract BACKGROUND Currently there are limited guidelines for the management of hyperbilirubinemia in preterm infants. Current guidelines are limited to individual sites and are consensus-based opinions. The current decrease in chronic bilirubin encephalopathy in preterm infants is a result of liberal use of phototherapy that are not based on evidence from a large dataset of preterm infants. The pattern of bilirubin levels in preterm is unclear and currently based on clinical judgement. Nomograms in term infants has been proven to be beneficial and effective in reducing unnecessary treatment of hyperbilirubinemia. A nomogram designed for preterm infants would allow health professionals to quantify risk based on evidence based methods and reduce the number of test done on preterm infants. OBJECTIVES The objectives of this study are 1) To determine photherapy thresholds in preterm infants and 2) To determine the normative pattern of bilirubin values in preterm infants. DESIGN/METHODS A multi-site retrospective chart review of preterm infants ≤ 35 weeks gestation born between January 2012- November 2017 was conducted. The following data was collected; all TSB, postnatal hours of age, duration of phototherapy, infant characteristics (gestational age, birth weight, outcomes) and maternal history (inter and anter partum medication). TSB samples prior to the initiation of phototherapy were analyzed per hour and stratified by gestational age groups. RESULTS A total of 330 preterm infants were included in the retrospective review (50 24-28 weeks gestation, 100 29-32 weeks gestation, and 180 33–35 weeks gestation). The mean peak bilirubin in infants 33-35 week gestation was 198 umol/L at 4 days. These infants were started on phototherapy at a mean age of 89 hours. At 24 hours of age these infants’ bilirubin was 104 umol/L (72-189umol/L). The mean peak bilirubin in infants 29–32 weeks gestation was 181umol/L at 5 days. At 24 hours of age the mean bilirubin was 109 umol/L. Finally in infants 24–28 weeks gestation the mean peak bilirubin was 127 umol/L at 4 days. These infants were started on phototherapy at 44 hours of age. CONCLUSION Bilirubin values in preterm infants is hetergenous across gestional ages. Phototherapy treatment thresholds are lower in preterm infants between 24–28 weeks gestation. A nomogram for preterm infants maybe possible in infants between 29–35 weeks. Further research is required to determine hour specific bilirubin levels in preterm infants.

Variable inhibition by falling CO2 of hypoxic ventilatory response in humans

1984 ◽  
Vol 56 (1) ◽  
pp. 207-210 ◽  
Author(s):  
L. G. Moore ◽  
S. Y. Huang ◽  
R. E. McCullough ◽  
J. B. Sampson ◽  
J. T. Maher ◽  
...  
Keyword(s):  
Ventilatory Response ◽  
Acute Hypoxia ◽  
Hypoxic Ventilatory Response ◽  
Co2 Response ◽  
Low Co2 ◽  
Two Factors ◽  
Variable Extent ◽  
The Difference ◽  
End Tidal ◽  
Ventilatory Response To Co2

Acute hypoxia stimulates an increase in ventilation but the resulting hypocapnia limits the magnitude of the increase. Thus the hypoxic ventilatory response is usually measured during isocapnia, but this may not reflect events at high altitude. We hypothesized that the degree of inhibition by hypocapnia might depend on individual ventilatory response to CO2 and thus vary between persons. To test this hypothesis we compared the isocapnic hypoxic ventilatory response (end-tidal PCO2 maintained by CO2 addition) with the response in which CO2 was not added and the end-tidal PCO2 fell to a variable extent (poikilocapnic hypoxia). In 14 healthy persons we found that the poikilocapnic hypoxic ventilatory response was determined by two factors: sensitivity to isocapnic hypoxia acting to increase ventilation and sensitivity to CO2 acting to decrease the hypoxic ventilatory response. The ventilatory response to poikilocapnic hypoxia correlated with but was generally less than the isocapnic hypoxic response. The magnitude of the difference between them related to the hypercapnic response. Further, the results suggested that the CO2 response in the high CO2 range related to ventilatory events in the low CO2 range. Thus the magnitude of ventilatory inhibition by hypocapnia may depend on individual ventilatory responsiveness to CO2.

The Ventilatory Response to CO2 after Administration of Frusemide in Normal Man

1972 ◽  
Vol 43 (1) ◽  
pp. 47-54 ◽  
Author(s):  
H. W. Iff ◽  
D. C. Flenley
Keyword(s):  
Ventilatory Response ◽  
Normal Subjects ◽  
Oxygen Balance ◽  
Co2 Response ◽  
Small Shift ◽  
Normal Man ◽  
Slight Rise ◽  
End Tidal ◽  
The Right ◽  
Ventilatory Response To Co2

1. We have determined the ventilatory response to CO2 inhaled in 30% oxygen (balance nitrogen) in eight normal subjects (1) before and during 4 days of 80 mg of oral frusemide daily and (2) within 55–75 min of 80 mg of frusemide orally. 2. Over 4 days the drug decreased serum potassium concentrations, but increased end tidal (and arterial) Pco2 and serum bicarbonate, thus inducing a mild metabolic alkalosis with an appropriate but small shift in CO2 response to the right without a significant change in the slope of the response. The CO2 response was unaltered by oral frusemide 55–75 min earlier. 3. This slight rise in Pco2 during 4 days of frusemide therapy contrasts with the absence of rise in Pco2 after treatment with thiazide diuretics, as reported by others. 4. We discuss possible implications of these results for the selection of an appropriate diuretic in patients with CO2 retention at various phases of their illness.

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