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Biomedical subjects

C F Poets

Publications and source records attributed to C F Poets.

At least 37 records · Page 2Linked to original sources
PubMed1999

Haemodynamic effects of altering arterial oxygen saturation in preterm infants with respiratory failure.

AIMS: To examine the haemodynamic effects of brief alteration in arterial oxygenation in preterm infants with respiratory failure. METHODS: Eighteen preterm infants with respiratory failure, aged 9-76 hours, underwent detailed Doppler echocardiographic assessment at 86%, 96%, and 100% SaO2, achieved by altering the FIO2. Sixteen were receiving intermittent positive pressure ventilation, median FIO2 0.45 (0.20-0.65), median mean airway pressure 12 cm H2O (0-20). SaO2 was stable for 15 minutes at each stage. Four parameters of pulmonary arterial pressure were measured: peak velocity of tricuspid regurgitation and peak velocity of left to right ductal flow, TPV:RVET ratio and PEP:RVET ratio, measured at the pulmonary valve, along with flow velocity integrals at the aortic and pulmonary valves, and systemic arterial pressure. Ductal size was graded into closed, small, moderate, large with imaging, pulsed and continuous wave Doppler. RESULTS: Between 86% and 96% SaO2, there were no consistent changes, but in three of the 12 with a patent ductus arteriosus (PDA) there was ductal constriction, with complete closure in one. Between 96% and 100% SaO2, peak ductal flow velocity rose significantly in four of eight with a PDA. Ductal constriction occurred in four infants; in three this was associated with a significant fall in aortic flow integral and a rise in aortic pressure (4-6 mm Hg). Overall, 11 infants went from 86% to 100% SaO2 and pulmonary arterial pressure fell significantly in seven. CONCLUSION: A brief rise in SaO2 within the range maintained by most neonatal units can cause significant ductal constriction. The fall in pulmonary arterial pressure with 100% SaO2 seen in most infants was associated with a fall in pulmonary blood flow (or no change), rather than a rise, indicating that the dominant haemodynamic effect was ductal constriction rather than pulmonary vasodilation.

Confidence Intervals↗
PubMed1999

Effect of doxapram on episodes of apnoea, bradycardia and hypoxaemia in preterm infants.

AIM: To study the effect of doxapram on the frequency of apnoea, bradycardia and hypoxaemia. METHODS: Fifteen infants, median gestational age at birth 27 weeks (range 24-30), age at study 27 days (12-60), with >/=6 episodes of bradycardia or hypoxaemia/6 h despite serum caffeine levels in the therapeutic range, received doxapram either intravenously (0.5-2 mg/kg/h) or orally (2-8 mg/kg every 2 h). Six-hour recordings of pulse oximeter saturation (S(P)O(2)), pulse waveforms, ECG, breathing movements and nasal airflow were performed immediately before as well as 1, 3 and 6 days after onset of treatment. Recordings were analysed for apnoea (>/=4 s), bradycardia (heart rate < 2/3 of baseline) and hypoxaemia (S(P)O(2) </=80%). RESULTS: There was no difference between enteral and intravenous administration; results are therefore presented for the total group. Doxapram resulted in a significant decrease in the frequency of apnoea [22 (11-27) vs. 14 (7-23)/h, p < 0.01], bradycardia [3 (0-7) vs. 1 (0-3)/h, p < 0.01] and hypoxaemia [8 (0-18) vs. 2 (0- 17)/h, p < 0.01] already after 1 day of treatment, which was sustained throughout the 6-day study period. Side effects included an increase in the proportion of time spent awake [5 (0-24) vs. 12% (3-28), p < 0.01] and in gastric residuals [0% of feeding volume (0-5) vs. 4% (0-19), p < 0.05]. Enteral was switched to intravenous doxapram in 3 of 9 infants because of gastrointestinal side effects. CONCLUSION: Doxapram substantially reduced the frequency of apnoea, bradycardia and hypoxaemia in these patients with caffeine-resistant apnoea of prematurity. Enteral administration, however, was not tolerated in a significant proportion (33%) of infants.

Apnea↗
PubMed1999

Gasping and other cardiorespiratory patterns during sudden infant deaths.

To gain information on the cardiorespiratory changes occurring immediately before sudden infant death (SID), recordings of heart rate and chest wall impedance were analyzed in nine infants who had died at a median age of 4.8 mo (range 1-6 mo) while attached to a memory monitor. Postmortem diagnoses were sudden infant death syndrome in seven infants and mild bronchopulmonary dysplasia in two infants. Primary cause of the monitor alarm was bradycardia in all but two infants. Heart rate fell to < or = 15 bpm 7.5 min (range 1.4-25.2 min) after the first alarm; there was no indication of heart block or ventricular tachycardia. Apnea (> 20 s) began 0.3 to 13.7 min (median 2.7 min) after this alarm in five infants and 7 to 20 s before it in three infants; in the remaining infant, stimulation occurred before any apnea. Gasping was already present at the time of the first monitor alarm in three infants and occurred within 2.7 min after it in a further four infants. One infant only began to gasp 13 min after the first monitor alarm. The duration of gasping ranged from 3 s to 11 min in those five infants in whom it was not interrupted by resuscitation. The latter was given to three infants 4, 21, and 228 s after the monitor alarm but had no effect on the ongoing decrease in heart rate. Since gasping only occurs if PaO2 is < 5-15 mm Hg, it is most likely that the seven infants who gasped at or shortly after the first monitor alarm were already severely hypoxemic at that time. This hypoxemia developed in the absence of prolonged central apnea. The role of other mechanisms potentially resulting in severe hypoxemia, such as upper airway obstruction or rebreathing, remains to be determined.

Apnea↗
PubMed1998

Effect of exposure to 15% oxygen on breathing patterns and oxygen saturation in infants: interventional study.

OBJECTIVE: To assess the response of healthy infants to airway hypoxia (15% oxygen in nitrogen). DESIGN: Interventional study. SETTINGS: Infants' homes and paediatric ward. SUBJECTS: 34 healthy infants (20 boys) born at term; mean age at study 3.1 months. 13 of the infants had siblings whose deaths had been ascribed to the sudden infant death syndrome. INTERVENTION: Respiratory variables were measured in room air (pre-challenge), while infants were exposed to 15% oxygen (challenge), and after infants were returned to room air (post-challenge). MAIN OUTCOME MEASURES: Baseline oxygen saturation as measured by pulse oximetry, frequency of isolated and periodic apnoea, and frequency of desaturation (oxygen saturation < or = 80% for > or = 4 s). Exposure to 15% oxygen was terminated if oxygen saturation fell to < or = 80% for > or = 1 min. RESULTS: Mean duration of exposure to 15% oxygen was 6.3 (SD 2.9) hours. Baseline oxygen saturation fell from a median of 97.6% (range 94.0% to 100%) in room air to 92.8% (84.7% to 100%) in 15% oxygen. There was no correlation between baseline oxygen saturation in room air and the extent of the fall in baseline oxygen saturation on exposure to 15% oxygen. During exposure to 15% oxygen there was a reduction in the proportion of time spent in regular breathing pattern and a 3.5-fold increase in the proportion of time spent in periodic apnoea (P < 0.001). There was an increase in the frequency of desaturation from 0 episodes per hour (range 0 to 0.2) to 0.4 episodes per hour (0 to 35) (P < 0.001). In 4 infants exposure to hypoxic conditions was ended early because of prolonged and severe falls in oxygen saturation. CONCLUSIONS: A proportion of infants had episodes of prolonged (< or = 80% for > or = 1 min) or recurrent shorter (< or = 80% for > or = 4 s) desaturation, or both, when exposed to airway hypoxia. The quality and quantity of this response was unpredictable. These findings may explain why some infants with airway hypoxia caused by respiratory infection develop more severe hypoxaemia than others. Exposure to airway hypoxia similar to that experienced during air travel or on holiday at high altitude may be harmful to some infants.

Disclosure↗
PubMed1998

Prenatal diagnosis of congenital alveolar proteinosis (surfactant protein B deficiency).

We report on the DNA-based prenatal diagnosis of congenital pulmonary alveolar proteinosis in a family in which alveolar proteinosis was associated with surfactant protein B (SP-B) deficiency. The parents had lost an eight-week-old female child due to this fatal disorder. The affected child was homozygous and both parents were heterozygous for a frame-shift mutation in codon 121 of the surfactant protein B gene (SFTP3-gene). Chorionic villus sampling (CVS) was performed in two subsequent pregnancies. DNA analysis revealed homozygosity for the codon 121 mutation in the first fetus, and the pregnancy was terminated. Homozygosity for the parental wild-type alleles was detected in the following prenatal diagnosis, and a healthy child has been born. DNA-based prenatal diagnosis of congenital alveolar proteinosis is simple, fast and reliable, and can be performed much earlier in pregnancy than any other method, e.g. the direct measurement of SP-B in amniotic fluid. In families with a term infant who dies of unexplained respiratory failure, genetic testing of the parents should be evaluated, since the presence of the codon 121 mutation enables prenatal diagnosis in later pregnancies.

Amniotic Fluid↗
PubMed1998

When do infants need additional inspired oxygen? A review of the current literature.

There is considerable uncertainty regarding the oxygen saturation threshold below which additional inspired oxygen should be given to infants with acute or chronic lung disease. In the absence of data from controlled studies, recommendations can only be based on reference values for healthy infants and on observational studies regarding the pathophysiological effects of acute and chronic hypoxia. Reference values for pulse oximeter saturations (SpO2) in term and preterm infants show that during normal breathing 95% of infants maintain SpO2 at or above 93-97%, depending on age. Studies of infants with chronic lung disease (CLD) show that (1) when SpO2 was kept at > or =93% by administration of home oxygen, rates of sudden infant death were reduced; (2) weight gain was significantly better when SpO2 was maintained at > or =93-95%, (3) increasing SpO2 from 82 to 93% by delivering low-flow oxygen resulted in a 50% reduction in pulmonary artery pressure, (4) O2 administration to mildly hypoxemic infants (SPO2 89%) caused a 50% decrease in airway resistance, and (5) low-flow oxygen reduced the frequency of intermittent hypoxemic episodes, even in infants who had values of > or =90% at rest. Based on these data, it is recommended that oxygen therapy should be considered in infants whose baseline SpO2 is <93%, and that SpO2 should be maintained at > or =95% when infants are managed at home.

Airway Resistance↗
PubMed1998

Donor pretreatment with ambroxol or dexamethasone fails to ameliorate reperfusion injury in experimental lung transplantation.

Based on the known properties of ambroxol and dexamethasone to inhibit inflammation and increase endogenous surfactant levels, the potential advantage of donor pretreatment with either drug was investigated in an acute rat double-lung transplant model. Donor animals were randomly assigned to one of three treatment groups: an ambroxol group (AMB; 0.4 mg/kg), a dexamethasone group (DX; 2 mg/kg); or an untreated control group (CN). Drugs were given intraperitoneally 6 h prior to harvest. Following standard preservation and 16 h of cold ischemia, the donor double lung block was implanted into syngeneic recipients using custom-designed stents for the vascular anastomosis. During reperfusion, serial measurements of graft pulmonary vascular resistance and alveolar-arterial oxygen difference were obtained. Separate graft ventilation allowed determination of graft dynamic lung compliance. Final assessment included weight gain and histology. For phospholipid analysis, lung lavages were performed in the three study groups at the end of reperfusion and compared to levels before graft harvest. Donor pretreatment did not significantly affect preharvest phospholipid levels. Survival following graft ischemia and reperfusion was shortest after AMB (92 +/- 5 min) and longest after DX (110 +/- 5 min; DX vs AMB P < 0.03) and CN (116 +/- 4 min; CN vs AMB P < 0.02). DX pretreatment provided better compliance (P < 0.02) and lower vascular resistance (P < 0.0001) than AMB treatment. Airway resistance was lower in the AMB and DX groups than in controls (P < 0.04 and P < 0.02, respectively). The alveolar-arterial oxygen difference was markedly similar in all groups. Graft weight gain amounted to 114% +/- 10% in AMB, 88% +/- 12% in DX, and 98% +/- 13% in CN (P = NS). Thus, in this rat lung transplantation model, donor pretreatment with dexamethasone did not improve graft function compared to untreated controls and donor pretreatment with ambroxol was found to be potentially detrimental to graft function during reperfusion.

Ambroxol↗
PubMed1998

Small airway patency in infants with apparent life-threatening events.

UNLABELLED: A reduction in specific airway conductance has been reported in infants with a history of an apparent life-threatening event (ALTE). It is unclear, however, whether this reflects upper or lower airway narrowing. We performed a controlled study to determine small airway patency in infants with ALTE. Lung function tests were performed in 26 infants with a history of ALTE and 27 healthy controls. Partial expiratory flow-volume curves were obtained during quiet sleep using the rapid chest compression technique; thoracic gas volume (TGV) and expiratory airway resistance (RAW) were measured by whole body plethysmography. Compliance of the respiratory system (Crs) was measured using the single breath occlusion technique. The median maximal flow at functional residual capacity (VmaxFRC) was 85 ml/s (range 10-198 ml/s) in patients and 123 (range 47-316 ml/s) in controls (P = 0.003). VmaxFRC corrected for TGV was 0.5 s(-1) (range 0.06-1.3 s[-1]) and 0.9 s(-1) (range 0.4-1.8 s[-1]), respectively (P = 0.001). TGV, RAW and Crs were not significantly different between patients and controls. CONCLUSION: Reduced small airway patency may play a role in the pathogenesis of ALTE.

Airway Obstruction↗
PubMed1998

[Acceptance of breast feeding and public discussion--evaluation of health campaigns for breast feeding between 1991 and 1995].

In 1990 the Innocenti Declaration on promoting breastfeeding was proclaimed in Florence/Italy. It became the subject of resolution 45.34 of the World Health Assembly in 1992. In the Federal Republic of Germany there was no wide-scale mass-media campaign to promote breastfeeding as in other countries. But mother-to-mother support groups, medical services and the newly founded National Breastfeeding Committee supported prolonged breastfeeding in public. The effects of the joint effort could be estimated by comparing the results of two postal surveys in 1991 and 1995. The surveys were conducted in Lower Saxony, North-Rhine-Westphalia and Berlin. A tendency could be shown toward more exclusive breastfeeding. Breastfeeding with supplementary food increased by a factor of 1.3 after adjusting for the variables mother's age, sleeping in parents' room or bed and no-smoking household. In Lower Saxony the increase was by a factor of 1.5 starting from a lower base value. The baby sleeping in the parents' room or in their bed furthered breastfeeding by a factor of 1.5 to 4. Non smoking mothers are 4 times more willing to breastfeed their infants than smoking mothers. German mothers breastfeed their infants two to three times more often than turkish mothers.

Adult↗
PubMed1997

Effects of salbutamol delivery from a metered dose inhaler versus jet nebulizer on dynamic lung mechanics in very preterm infants with chronic lung disease.

Treatment of chronic lung disease of prematurity requires effective aerosol delivery of different therapeutic agents. Aerosols can be generated by a metered dose inhaler (MDI) or a jet nebulizer. An MDI combined with a spacer device is easier to use and avoids undesirable effects noted in conjunction with jet nebulization. We compared the clinical effectiveness of 200 micrograms (2 puffs) salbutamol delivered from an MDI in conjunction with a valved spacer device (Aerochamber), and 600 micrograms given via jet nebulizer (PariBaby) on 2 consecutive days, the order being randomized. Thirteen spontaneously breathing very preterm infants [mean (SD) gestational age 27.2 (1.8) weeks; birth weight 0.90 (0.34) kg] were studied at a corrected age of 37 (2.3) weeks. Mean (SD) study weight was 1.83 (0.38) kg. Dynamic lung compliance and resistance were determined from measurements of flows, volumes, and transpulmonary pressures, using a pneumotachometer and a small esophageal microtransducer catheter before and 20 min after salbutamol application. Baseline values before salbutamol administration were similar on both occasions: the mean (SD) compliance was 7.7 (3.0) mL.kPa-1.kg-1 pre-MDI plus-spacer and 8.4 (3.1) pre-jet nebulizer; the resistance was 10.4 (4.0) kPa.L-1.s pre-MDI plus-spacer and 9.7 (3.4) pre-jet nebulizer. Following salbutamol, compliance did not change significantly with either MDI plus spacer or jet nebulizer. Resistance fall significantly with MDI plus spacer (mean -2.2; 99.9% CI -0.35, -4.35) and jet nebulizer (-2.4; 99% CI -0.39, -4.42). We conclude that even in small preterm infants 200 micrograms salbutamol via MDI plus spacer improves dynamic resistance as effectively as 600 micrograms via jet nebulizer and may therefore be a preferable mode of aarosol administration.

Administration, Inhalation↗
PubMed1997

Effect of blood transfusion on apnoea, bradycardia and hypoxaemia in preterm infants.

UNLABELLED: We studied the effect of blood transfusion on the frequency of apnoea, bradycardia and hypoxaemia in 21 spontaneously breathing preterm infants with a median gestational age at birth of 28 (range 23-31) weeks. Age at time of study was 22 days (3-84), weight 925 g (640-2120). The patients exhibited frequent episodes of bradycardia and/or hypoxaemia and were anaemic (median haemoglobin level 109 (82-120) g/l). One infant received two transfusions and was thus studied twice. Four-hour recordings of pulse oximeter saturation (SpO2), pulse waveforms, transcutaneous oxygen pressure, electrocardiogram, breathing movements and nasal airflow were performed immediately before and after transfusion, and again after a further interval of 12 h. Recordings were analysed for isolated and periodic apnoeas (> 4 s), bradycardias (heart rate < 2/3 of baseline), and episodic desaturation (SpO2 < or = 80%). There were no significant changes in the frequency, severity and/or duration of apnoea, bradycardia or desaturation following transfusion. The average SpO2 nadir reached during each desaturation, however, increased by 3% following transfusion (P < 0.05), and there was a trend towards shorter desaturations. CONCLUSION: The occurrence of frequent episodes of apnoea, bradycardia and/or hypoxaemia does not, on its own, justify a blood transfusion in moderately anaemic preterm infants.

Anemia↗
PubMed1997

Blood transfusion. Iron load and retinopathy of prematurity.

UNLABELLED: To study the relationship between blood transfusion, iron load and retinopathy of prematurity (ROP), we performed a prospective observational cohort study in a level III neonatal intensive care unit. During a 24-month period, data on the volume of blood transfused during the first 6 weeks of life and on the incidence of ROP were collected in all surviving very low birth weight infants (n = 114; median birth weight 1130 g. range 520-1500 g). Associations between these data and values for serum iron, transferrin and ferritin measured at weekly intervals were analysed in a nested case-control design by logistic regression. There was a significant association between the volume of blood transfused and the incidence of ROP. After adjustment for gestational age at birth, duration of oxygen therapy (FiO2 > 0.3) and duration of mechanical ventilation, the relative risk of developing ROP was 6.4 (95% CI 1.2-33.4) for infants who had received 16-45 ml/kg, and 12.3 (1.6-92.5) for those who had received more than 45 ml/kg of blood (reference, 0-15 ml/kg). In contrast, there was no independent relationship between ROP and any of the parameters on iron metabolism analysed. CONCLUSION: This study confirms the role of blood transfusions as an independent risk factor for ROP. This relationship, however, does not appear to be mediated via an increased iron load.

Case-Control Studies↗
PubMed1997

Detection of movement artifact in recorded pulse oximeter saturation.

UNLABELLED: Movement artifact (MA) must be detected when analysing recordings of pulse oximeter saturation (SpO2). Visual analysis of individual pulse waveforms is the safest, but also the most tedious, method for this purpose. We wanted to test the reliability of a computer algorithm (Edentec Motion Annotation System), based on a comparison between pulse and heart rate, for MA detection. Ten 12-h recordings of SpO2, pulse waveforms and heart rate from ten preterm infants were analysed for the presence of MA on the pulse waveform signal. These data were used to determine the sensitivity and specificity of the computer algorithm, and of the oximeter itself, in detecting MA. Recordings were divided into segments of 2.5 s duration to compare the movement identification methods. Of the segments 31% +/- 6% (mean +/- SD) contained MA. The computer algorithm identified 95% +/- 3% of these segments, the pulse oximeter only 18% +/- 11%. Specificity was 85% +/- 4% and 99% +/- 0%, respectively. SpO2 was < or =80% in 3% +/- 1% of segments. 88% +/- 7% of the pulse waveform signal showed MA during this time, leaving a significant potential for erroneous identification of hypoxaemia. Recordings of SpO2 do not allow a reliable identification of MA. CONCLUSION: Without additional information about movement artifact, a significant proportion of recording time of pulse oximeter signal may be regarded as demonstrating hypoxaemia which, in fact, simply reflects poor measurement conditions. The computer algorithm used in this study identified periods of movement artifact reliably.

Algorithms↗
PubMed1997

In vivo measurement of lung preservation solution efficacy: comparison of LPD, UW, EC and low K+-EC following short and extended ischemia.

OBJECTIVE: The impact of storage solution composition on graft performance was evaluated following perfusion with either Euro-Collins (EC), low potassium Euro-Collins (rEC), low potassium dextran (LPD) or University of Wisconsin solution (UW) after brief (2 h) and extended ischemia (16 h) in an acute double lung transplantation model in the rat. METHODS: Following flush perfusion and ischemia the lungs were implanted in recipient rats allowing serial assessment of graft pulmonary vascular resistance (PVR) and alveolar arterial oxygen difference (AaDO2) during 120 min of reperfusion. Graft dynamic lung compliance (DLC) was determined by separate ventilation. Final evaluation included weight gain and histology. RESULTS: After extended ischemia LPD provided superior graft function in respect to DLC (repeated measures ANOVA; LPD versus rEC P < 0.05; versus EC P < 0.03; versus UW P < 0.05) and AaDO2 (LPD versus rEC P < 0.04; versus EC P < 0.006). The PVR was significantly lower in LPD versus UW (P < 0.05). At the end of reperfusion the weight increase amounted to 229 +/- 49% in rEC, 207 +/- 22% in EC, 115 +/- 22% in UW and 87 + 17% in LPD (LPD versus rEC P < 0.01, LPD versus EC P < 0.001). The type of preservation solution used had little impact on graft function after 2 h ischemia. CONCLUSIONS: Low potassium dextran provides superior graft function after extended ischemia. After short ischemia the type of preservation solution used in this study had little impact on global lung function.

Adenosine↗
PubMed1997

Active surfactant in pharyngeal aspirates of term neonates: lipid biochemistry and surface tension function.

Alveolar surfactant is well known for its ability to reduce minimal surface tension at the alveolar air-liquid interface to values below 5 mN m-1. In addition, it has been suggested that surfactant is also present in the airways, particularly in the perinatal period. We isolated surfactant from pharyngeal aspirates obtained from 33 neonates immediately after delivery and analysed it for both phospholipid (PL) composition and surface tension function. PL classes and phosphatidylcholine (PC) molecular species were determined by normal and reversed-phase high-performance liquid chromatography (HPLC), respectively. Static and dynamic surface properties of the surfactant were studied in a pulsating bubble surfactometer. Sample volume was 1.3 +/- 0.5 mL (mean +/- SD) with a total amount of 2.5 +/- 1.3 mumol of PL and a concentration of 2.1 +/- 1.0 mumol mL-1 PL. HPLC analyses of PL classes revealed a composition identical with surfactant prepared from alveolar washes, i.e. PC 83.6 +/- 2.1%, sphingomyelin 1.4 +/- 0.5%, phosphatidylglycerol 8.1 +/- 1.6%, phosphatidylethanolamine 2.1 +/- 0.5% and phosphatidylinositol 2.6 +/- 1.1%. Thin-layer chromatography showed almost identical results but was more time-consuming and needed more material for analysis. Analysis of PC molecular species revealed a composition typical of human alveolar surfactant with 54.7 +/- 3.9% dipalmitoyl PC, 10.3 +/- 1.9% palmitoyloleoyl PC and 9.1 +/- 1.5% palmitoylmyristoyl PC. Minimal surface tension fell to values below 5 mNm-1 within 5 min of cycling in all subjects. The methods used in this study allowed for complete PL and surface tension analyses of surfactant obtained during routine pharyngeal suctioning after delivery at term. Whether they are also applicable to preterm neonates with respiratory distress remains to be determined.

Humans↗
PubMed1997

Effects of bottle feeding and two different methods of gavage feeding on oxygenation and breathing patterns in preterm infants.

OBJECTIVE: To determine the effect of bottle feeding, as compared to two methods of gavage feeding, on apnoea, bradycardia and oxygen desaturation frequency. PATIENTS: Thirty preterm infants breathing room air; gestational age 28.6 +/- 2.1 weeks at birth and 34 +/- 1.4 weeks at study (mean +/- SD). METHODS: Nine-hour recordings of pulse oximeter saturation (SpO2), pulse waveforms, electrocardiogram, breathing movements and nasal airflow. Administration of 21 +/- 1.5 ml/kg of milk/feed in 3-h intervals using three different feeding techniques in random order: bottle feeding, bolus gavage feeding, and slow gavage feeding (1 h). Analysis of recordings for apnoeas (> or =4s, bradycardias (heart rate < 2/3 of baseline), and episodic desaturation (SpO2 < or = 80%). RESULTS: There were three times more desaturations with bottle feeding than with bolus gavage feeding (p < 0.001), but no further reduction with slow gavage feeding. With all three feeding techniques, there were significantly more desaturations in the hour when the feeds were given than during the following 2 h. The deleterious effects of bottle feeding were most evident during the hour of feeding, but desaturation frequency remained significantly higher than with gavage feeding during the following 2 h. There was no significant effect of feeding technique on the frequency of apnoea or bradycardia. CONCLUSIONS: Preterm infants who are normally oxygenated in room air may have significant desaturation during bottle feeding. Such desaturation can be effectively reduced by gavage feeding. Slow gavage feeding offers no advantage over bolus gavage feeding with respect to the avoidance of hypoxaemia.

Apnea↗
PubMed1997

Determinants of lung volume in spontaneously breathing preterm infants.

To study the effects of apneic pauses, sighs, and breathing patterns on functional residual capacity (FRC), we measured FRC repeatedly in 48 healthy preterm infants (weight at study 2,042 +/- 316 g [mean +/- SD], postconceptional age 36.6 +/- 2.0 wk), during unsedated sleep using a modified heliox/nitrogen washout technique. Breathing movements and pulse oximeter saturation (SpO2) were recorded throughout and recordings analyzed for the presence of regular and nonregular breathing pattern, apneic pauses, sighs, and desaturations (SpO2 < 90%) during the last 2 min prior to each FRC measurement. FRC was lower during nonregular than during regular breathing pattern (23.3 +/- 7.2 ml/kg versus 26.9 +/- 7.8 ml/kg, p < 0.02); however, this apparent effect of breathing pattern disappeared after controlling the data for apneic pauses. Apneic pauses resulted in a significant decrease in FRC: mean FRC was 20.0 +/- 6.8 ml/kg if measured within 2 min of an apneic pause, 26.0 +/- 6.9 ml/kg if measured after a sigh (p < 0.001), and 24.0 +/- 7.7 ml/kg if there had been neither a sigh nor an apneic pause (p < 0.05). The interval between the apneic pause and the FRC measurement had no effect on FRC. There was an inverse correlation between FRC and the speed with which SpO2 fell during desaturation (r = -O.5, p < 0.03). Apneic pauses resulted in a persistent reduction in FRC in these preterm infants. Sighs appeared to restore FRC. The significant relationship between FRC and the speed of desaturation found in this study underscores the importance of endogenous or exogenous strategies that help to increase FRC, such as sighs or the application of continuous positive airway pressure, for the stability of oxygenation in preterm infants who have difficulty maintaining their oxygenation.

Female↗