Ventilated Preterm Infants Research Articles

Effect of external inspiratory loading on ventilation of premature infants.

The ventilatory response of 11 growing premature infants to external inspiratory resistive loads was evaluated. Air flow, tidal volume, minute ventilation, inspiratory duration and total breath duration were measured before and after application of a flow resistive load. A significant (P less than 0.001) immediate decrease in minute ventilation and tidal volume was observed in all infants after load application. Minute ventilation and tidal volume remained decreased throughout the 10-min study period. Minute ventilation and tidal volume for the group decreased to 48 and 50% of control mean value, respectively. In addition, there was a significant (P less than 0.001) sustained increase in inspiratory time resulting in an increase in the ratio of inspiratory time/total respiratory time.

High-Frequency Ventilation in Premature Infants with Lung Disease

FRANTZ, I. D. III; WERTHAMMER, J.; STARK, A. R.; Vitez, Terry S. M.D. Author Information

Decreased ventilation in preterm infants during oral feeding

As respiratory difficulty may accompany nipple feeding in preterm neonates, we studied the effect of oral feeding on ventilation in 23 preterm infants. The infants composed two groups based on their postconceptional age at the time of study: Group A comprised 12 infants 34 to 35.9 weeks of age, and group B, 11 infants 36 to 38 weeks. Ventilation was measured via a nasal mask pneumotachometer, and sucking pressure via a nipple that also permitted milk delivery; transcutaneous PO2 and PCO2 were continuously monitored. The feeding pattern comprised an initial period of continuous sucking of at least 30 seconds, followed by intermittent sucking bursts for the remainder of the feed. When compared with an initial semi-upright control period, minute ventilation (V1) during continuous sucking fell by 52 +/- 6% (P less than 0.001) and 40 +/- 2% (P less than 0.001) in groups A and B, respectively. This was the result of a decrease in respiratory frequency and tidal volume and was associated with a fall in TcPO2 of 13 +/- 4 mm Hg (P less than 0.01) in group A and 10 +/- 2 mm Hg (P less than 0.01) in group B. During intermittent sucking, V1 and TcPO2 recovered partially only in the more mature infants (group B). At the end of the feed, TcPCO2 have risen by 3 +/- 1 mm Hg (P less than 0.001) in group A and by 2 +/- 2 mm Hg (P less than 0.05) in group B. Thus oral feeding results in an impairment of ventilation during continuous sucking and the subsequent recovery during intermittent sucking is dependent on postconceptional age.

Effects of vitamin D and phosphorus supplementation on calcium retention in preterm infants fed banked human milk

aminophylline demonstrated decreased Paco2, increased minute ventilation, and increased respiratory rate, as compared with Pretreatment values. One explanation for the successful extubation of infants after aminophylline therapy is suggested by the increase in minute ventilation coinciding with a decrease in arterial carbon dioxide tension in treated infants. Theophylline increases metabolic rate in animals, 4 decreases apnea, 15'6 increases respiratory muscle efficiency, 7 and increases central COz responsivenessY ~ Improved ventilatory response to lower carbon dioxide levels suggests that aminophylline stimulates the central nervous system chemoreceptors for CO2 response? This hypothesis is consistent with the observation that many very LBW infants appear apneic when ventilated at rates less than 6 bpm, but when given aminophylline, may improve sufficiently to be extubated. A previous study of infants with bronchopulmonary dysplasia 3 suggested that theophylline relaxed smooth muscle in hypertrophied small bronehioles. The infants in our study did not demonstrate clinical, radiographic, or pulmonary function evidence of bronchopulmonary dysplasia, and therefore smooth muscle relaxation is an unlikely explanation for the improvement observed. Aminophylline therapy allowed weaning of LBW infants with respiratory distress syndrome from low levels of mechanical ventilatory support and successful endotracheal extubation of most treated patients. Methylxanthine therapy should be considered to promote weaning of infants with respiratory distress syndrome from low rates of ventilatory support and to facilitate extubation. REFERENCES 1. Aranda .IV, Turmen T: Methylxanthines in apnea of prematurity. Clin Perinatol 6:87, 1979. 2. Daily W JR, Klaus M, Meyer HBP: Apnea in premature infants: Monitoring, incidence, heart rate changes and an effect of environmental temperature. Pediatrics 43:510, 1969. 3. Rooklin AR, Moomjian AS, Shutack JG, Schwartz JG, Fox WW: Theophylline therapy in bronchopulmonary dysplasia. J P~DIATR 95:882, 1979. 4. Thurston JH, Hauhart RE, Dirgo JA: Aminophylline increases cerebral metabolic rate and decreases anoxic survival in young mice. Science 201:649, 1978. 5. Aranda .IV, Grondin D, Sasyniuk BI: Pharmacologic considerations in the therapy of neonatal apnea. Pediatr Clin North Am 28:113, 1981. 6. Bednarek F.I, Roloff DW: Treatment ofapnea of prematurity with aminophylline. Pediatrics 58:335, 1976. 7. Aubier M, Detroyer A, Sampson M, Maklim PT, Ronssoc C: Amonophylline improves diaphragmatic contractility. N Engl .I Med 305:249, 1981. 8. Aranda .IV, Zinman R, Collinge J, Outerbridge EW: Effect of caffeine on control of ventilation in premature infants with apnea. Clin Pharmacol Ther 25:212, 1979. 9. Gerhardt T, McCarthy J, Bancalari E: Effect of aminophylline on respiratory center activity and metabolic rate in premature infants with idiopathic apnea. Pediatrics 63:537, 1979. 10. Davi M J, Sankaran K, Simons K J, Simons ER, Seshia MM, Rigatto H: Physiologic changes induced by theophylline in the treatment of apnea in preterm infants. J PEDIATR 92:91, 1978.

Oesophageal pressure measurements in ventilated preterm babies

Oesophageal pressure measurements in ventilated preterm babies

Oesophageal pressure measurements in ventilated preterm babies.

Oesophageal pressure measurements in ventilated preterm babies.

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

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, end-tidal PO2, and transcutaneous PO2. CPAP significantly decreased minute ventilation from 278.7 to 197.6 mL/min/kg (P less than .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 greater than .1), but the intercept was shifted to the right (P less than .001). The decrease in respiratory frequency was primarily due to a prolongation of expiratory time (P less than .05). In addition, transcutaneous PO2 increased during administration of CPAP (P less than .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.

High-Frequency Ventilation in Premature Infants with Lung Disease: Adequate Gas Exchange at Low Tracheal Pressure

The technique of high-frequency ventilation (HFV) was used in ten infants with severe respiratory distress syndrome and five infants with pulmonary interstitial emphysema (PIE). The mean frequency used was 12 Hz (720/min). Peak tracheal pressure for the infants with respiratory distress syndrome was 28 +/- 4 (SD) cm H2O on conventional ventilation, and 22 +/- 4 cm H2O on HFV (P less than .05). For the infants with PIE, peak tracheal pressure decreased from 38 +/- 11 to 24 +/- 5 cm H2O (P less than .05). Mean tracheal pressure was the same for the two types of ventilation. No adverse clinical or pathologic side effects were seen. Clinical and radiologic improvements were seen in the infants with PIE after initiation of HFV. It is believed that these improvements in the patients with PIE were secondary to the decrease in tracheal pressure and that HFV may have a role in treatment of preexisting barotrauma and its prevention. These studies contribute to the preliminary data necessary before controlled trials of HFV in infants with respiratory distress syndrome and PIE can be carried out.

Oesophageal pressure measurements in ventilated preterm babies.

Oesophageal pressure measured with an air-filled, thin latex balloon on a 6 French gauge catheter can accurately measure intraoesophageal pressures in ventilated preterm babies. Intraoesophageal pressures and intrapleural pressures are equivalent. Less than 10% of the applied positive ventilator pressure is transmitted to the oesophageal balloon and the intrapleural catheter (intercostal drain). The oesophageal traces show that ventilated babies breath independently of the ventilator. The largest deflections recorded from the oesophageal trace are from spontaneous inspiratory activity. During paralysis with pancuronium spontaneous respiration is inhibited, peristaltic waves are still recorded, and there is little transmitted pressure from the ventilator to the oesophagus or intercostal drain.

Progressive interstitial pulmonary lobar emphysema

Progressive pulmonary interstitial lobar emphysema is a complication of artificial ventilation in premature infants with RDS. Three cases are presented who developed a progressive form of PIPE. It is demonstrated that PIPE is caused by air escaping through alveolar leaks into the pulmonary lymphatic capillary system causing dilation of lymphatic channels. Because of its increasing compressive effect on adjacent lung areas PIPE requires rapid and effective therapy. Although several types of conservative approach are suggested, lobectomy is not indicated when prolonged ventilation with high pressures and high concentrations of oxygen have caused severe bronchopulmonary dysplasia.

Air Embolism From Mechanical Ventilation in Respiratory Distress Syndrome

Three cases of air embolism secondary to mechanical ventilation in premature infants with respiratory distress syndrome are presented, and its mechanism is discussed. A plausible mechanism for air in the hepatic veins occurring in most of these cases is also discussed. Many sudden unexplained deaths in premature infants on mechanical ventilation may be due to air embolism, which should be recognized as a component of neonatal "air-block syndrome."

Intermittent bag ventilation of preterm infants on continuous positive airway pressure: The effect on transcutaneous Po 2

Preterm infants with respiratory distress syndrome requiring continuous positive airway pressure are frequently assisted with intermittent bag ventilation. We assessed the effect of intermittent bag ventilation on PO2 in these infants by continuous monitoring with a transcutaneous oxygen electrode. The behavior of the infants during bagging determined the effect on PO2. Bag ventilation decreased PO2 significantly (P less than 0.01) in infants who were restless during bagging, whereas a significant increase in PO2 (P less than 0.02) was observed in infants who were quiet while being bagged. Although the duration of the increase in PO2 was variable, a sustained rise (greater than 20 minute) occurred in almost half of the infants studied. Intermittent bag ventilation appears to be beneficial in infants who remain quiet during the bagging period.

HYPOXIA IN PRETERM INFANTS: EVIDENCE FOR CENTRAL RESPIRATORY DEPRESSION

Hypoxia depresses ventilation in preterm infants. Because PACO2 does not rise, the decrease in ventilation has been attributed to a decrease in metabolism rather than to the central depressant effect of hypoxia. To determine whether central depression is present, we measured the ventilatory sensitivity to CO2 at varying inspired O2 concentrations in preterm infants. Eight babies (B.W.I to 2 kg;G.A.<36 weeks) were studied 10 times during the first 10 days of life. After breathing 21% O2 for 3 minutes, they were given 15,21,40 or 100% O2 for 4 minutes and then 2% CO2 plus the various concentrations of O2 for 4 minutes each. We determined respiratory minute volume and frequency, PACO2, PAO2 and heart rate. Ventilation was measured with a nosepiece and screen flowmeter, using a constant flow-through to eliminate dead space and valves. We plotted minute ventilation against PACO2 to assess the respiratory sensitivity at varying inspired O2 concentrations. The mean slopes of the CO2 response curves were 0.011, 0.022, 0.039 and 0.168 L/min/kg/mm Hg PACO2 with 15,21,40 and 100% inspired O2 respectively (p<0.05). Therefore, the more hypoxic the infant, the flatter was the response to CO2. These findings suggest: a)the respiratory center is depressed during hypoxia in preterm infants despite a decrease in PACO2; b) the response to inhaled CO2 is the opposite to that seen in male adults, where the higher the inspired O2 concentration, the flatter the response.

Airway closure in children.

Airway closure in children.

A new nosepiece for measuring ventilation in preterm infants.

ARTICLESA new nosepiece for measuring ventilation in preterm infantsH. Rigatto, and J. P. BradyH. Rigatto, and J. P. BradyPublished Online:01 Mar 1972https://doi.org/10.1152/jappl.1972.32.3.423MoreSectionsPDF (333 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat "A new nosepiece for measuring ventilation in preterm infants." Journal of Applied Physiology, 32(3), pp. 423–424 Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByThe effect of rebreathing CO2 on ventilation and diaphragmatic electromyography in newborn infantsRespiration Physiology, Vol. 62, No. 3Ventilatory response to 100% and 15% O2 during wakefulness and sleep in preterm infantsEarly Human Development, Vol. 7, No. 1Tidal volume and respiratory frequency in infants with bronchopulmonary dysplasia (BPD)Early Human Development, Vol. 5, No. 1The effect of 2% CO2, 100% O2, theophylline and 15% O2 on ‘inspiratory drive’ and ‘effective’ timing in preterm infantsEarly Human Development, Vol. 5, No. 1Chemical control of respiratory frequency and tidal volume during sleep in preterm infantsRespiration Physiology, Vol. 41, No. 1Determinants of distortions in CO2 catheter sampling systems: A mathematical modelRespiration Physiology, Vol. 41, No. 1 More from this issue > Volume 32Issue 3March 1972Pages 423-424 Copyright & PermissionsCopyright © 1972 the American Physiological Societyhttps://doi.org/10.1152/jappl.1972.32.3.423PubMed5010053History Published online 1 March 1972 Published in print 1 March 1972 Metrics

Pulmonary edema in dogs, especially the sequence of fluid accumulation in lungs.

Pulmonary edema in dogs, especially the sequence of fluid accumulation in lungs.