RESUMO
OBJECTIVE: Ballard scores are commonly used to estimate gestational age (GA). The purpose of this study was to determine the accuracy of the New Ballard Score (NBS) for infants <28 weeks GA by accurate menstrual history and to evaluate NBS as an outcome predictor. METHODS: Infants weighing 401 to 1500 g in 12 National Institute of Child Health and Human Development Neonatal Research Network centers had NBS performed before age 48 hours. Accuracy of NBS estimates of GA was assessed for infants with GA determined by accurate menstrual history. In a larger cohort of infants, NBS was included in regression models of the association of NBS and death, poor outcome, and duration of hospital stay. RESULTS: At each week from 22 to 28 weeks GA by accurate menstrual history, NBS estimates exceeded GA by dates by 1.3 to 3.3 weeks, and estimates varied widely (range of widths of 95% CIs for the observations, 6.8 to 11.9 weeks). NBS did not contribute significantly to regression models of death, poor outcome, or duration of hospital stay. CONCLUSIONS: Inaccuracies in GA determined by the NBS should be considered when treating extremely premature infants, particularly in decisions to forego or administer intensive care. Refinement of GA scoring systems is needed to optimize clinical benefit.
Assuntos
Idade Gestacional , Recém-Nascido Prematuro/crescimento & desenvolvimento , Recém-Nascido de muito Baixo Peso/crescimento & desenvolvimento , Exame Neurológico/métodos , Exame Físico/métodos , Feminino , Humanos , Recém-Nascido , Terapia Intensiva Neonatal , Modelos Lineares , Modelos Logísticos , Menstruação , Razão de Chances , Gravidez , Reprodutibilidade dos TestesRESUMO
OBJECTIVE: We carried out a randomized placebo-controlled trial in very low birth weight neonates (VLBWNs), comparing the incidence of nosocomial infections after the prophylactic use of recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF) versus placebo in VLBWNs. STUDY DESIGN: VLBWNs (n = 264), weighing 501 to 1000 g, /=4000/mm,3 peripheral blood progenitor studies, and 24-hour polymorphonuclear leukocyte C3bi receptor expression were compared between the 2 treatment groups. RESULTS: No (grade III/IV) toxicity or adverse events were associated with rhu GM-CSF. The absolute neutrophil count and absolute eosinophil count were significantly elevated in the rhu GM-CSF group on days 7 (P =.001), 14 (P =.001), and 21 (P =.007) and on days 7 and 28 (P =.012 and P =.001, respectively). However, there was no difference in the incidence of confirmed nosocomial infections between the 2 treatment groups in this trial (40% vs 39%, rhu GM-CSF vs placebo; P = NS). CONCLUSION: In a large randomized placebo-controlled trial, prophylactic administration of rhu GM-CSF in VLBWNs does not appear to decrease the incidence of nosocomial infections.
Assuntos
Infecção Hospitalar/prevenção & controle , Fator Estimulador de Colônias de Granulócitos e Macrófagos/uso terapêutico , Recém-Nascido de muito Baixo Peso , Método Duplo-Cego , Eosinófilos/efeitos dos fármacos , Feminino , Humanos , Recém-Nascido , Injeções Intravenosas , Contagem de Leucócitos/efeitos dos fármacos , Masculino , Proteínas Recombinantes , Estados UnidosRESUMO
OBJECTIVE: Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 7861 VLBW (401 to 1500 gm) neonates admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991 to 1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry of all VLBW neonates cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Of 6911 infants who survived beyond 3 days, 1696 (25%) had one or more episodes of blood culture-proven sepsis. The vast majority of infection (73%) were caused by gram-positive organisms, with coagulase-negative staphylococci accounting for 55% of all infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of infection included intubation, respiratory distress syndrome, prolonged ventilation, bronchopulmonary dysplasia, patent ductus arteriosus, severe intraventricular hemorrhage, and necrotizing enterocolitis. Among infants with bronchopulmonary dysplasia, those with late-onset sepsis had a significantly longer duration of mechanical ventilation (45 vs 33 days; p <0.01). Late-onset sepsis prolonged hospital stay: the mean number of days in the hospital for VLBW neonates with and without late-onset sepsis was 86 and 61 days, respectively (p <0.001). Even after adjustment for other complications of prematurity, including intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia, infants with late-onset sepsis had a significantly longer hospitalization (p <0.001). Moreover, neonates in whom late-onset sepsis developed were significantly more likely to die than those who were uninfected (17% vs 7%; p <0.000 1), especially if they were infected with gram-negative organisms (40%) or fungi (28%). Deaths attributed to infection increased with increasing chronologic age. Whereas only 4% of deaths in the first 3 days of life were attributed to infection, 45% of deaths after 2 weeks were related to infection. CONCLUSIONS: Late-onset sepsis is a frequent and important problem among VLBW preterm infants. Successful strategies to decrease late-onset sepsis should decrease VLBW mortality rates, shorten hospital stay, and reduce costs.
Assuntos
Recém-Nascido de muito Baixo Peso , Sepse/epidemiologia , Idade de Início , Infecções Bacterianas/epidemiologia , Infecções Bacterianas/microbiologia , Infecções Bacterianas/mortalidade , Candidíase/epidemiologia , Candidíase/microbiologia , Candidíase/mortalidade , Causas de Morte , Estudos de Coortes , Feminino , Humanos , Incidência , Recém-Nascido , Tempo de Internação , Masculino , Análise Multivariada , Estudos Prospectivos , Sistema de Registros , Fatores de Risco , Sepse/microbiologia , Sepse/mortalidadeRESUMO
OBJECTIVE: Early-onset sepsis (occurring within 72 hours of birth) is included in the differential diagnosis of most very low birth weight (VLBW) neonates. To determine the current incidence of early-onset sepsis, risk factors for disease, and the impact of early-onset sepsis on subsequent hospital course, we studied a cohort of 7861 VLBW neonates (401 to 1500 gm) admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991-1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry on all VLBW neonates born or cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Blood culture-proven early-onset sepsis was uncommon, occurring in only 1.9% of VLBW neonates. Group B streptococcus was the most frequent pathogen associated with early-onset sepsis (31%), followed by Escherichia coli (16%) and Haemophilus influenzae (12%). Decreasing gestational age was associated with increased rates of infection. Antibiotic therapy for suspected sepsis is frequently initiated at birth in VLBW neonates. Almost half of the infants in this cohort were considered to have clinical sepsis and continued to receive antibiotics for 5 or more days, despite a negative blood culture result in 98% of cases. These findings underscore the difficulty of ruling out sepsis in the symptomatic immature neonate and the special concern for culture-negative clinical sepsis in the face of maternal antibiotic use. Neonates with early-onset sepsis were significantly more likely to have subsequent comorbidities, including severe intraventricular hemorrhage, patent ductus arteriosus, and prolonged assisted ventilation. Although 26% of VLBW neonates with early-onset sepsis died, only 4% of the 950 deaths that occurred in the first 72 hours of life were attributed to infection. For those infants discharged alive, early-onset sepsis was associated with a significantly prolonged hospital stay (86 vs 69 days; p <0.02). CONCLUSIONS: Early-onset sepsis remains an important but uncommon problem among VLBW preterm infants. Improved diagnostic strategies are needed to enable the clinician to distinguish between the infected and the uninfected VLBW neonate with symptoms and to target continued antibiotic therapy to those who are truly infected.
Assuntos
Recém-Nascido de muito Baixo Peso , Sepse/epidemiologia , Idade de Início , Infecções Bacterianas/epidemiologia , Infecções Bacterianas/microbiologia , Infecções Bacterianas/mortalidade , Estudos de Coortes , Feminino , Humanos , Incidência , Recém-Nascido , Masculino , Fatores de Risco , Sepse/microbiologia , Sepse/mortalidadeRESUMO
OBJECTIVE: To compare the efficacy of two surfactants, Exosurf Neonatal (Burroughs Wellcome Co.) and Survanta (Ross Laboratories), for the treatment of neonatal respiratory distress syndrome. DESIGN: Multicenter randomized trial. SETTING: Eleven tertiary care university neonatal intensive care units participating in the National Institute of Child Health and Human Development Neonatal Research Network. PATIENTS: Newborn infants (n = 617) weighing 501 to 1500 gm with respiratory distress syndrome who were receiving assisted ventilation with 30% oxygen or more within 6 hours of birth were enrolled between January 1991 and January 1992. INTERVENTIONS: Infants were randomly assigned to receive up to four intratracheal doses of either Exosurf Neonatal (n = 309) or Survanta (n = 308). MAIN OUTCOME MEASURES: The occurrence of death or bronchopulmonary dysplasia 28 days after birth and the average fraction of inspired oxygen (FIO2) and mean airway pressure (MAP) during the first 72 hours after treatment. RESULTS: Death or bronchopulmonary dysplasia occurred in 67% of the infants in the Exosurf group and 62% of those in the Survanta group (adjusted relative risk, 1.07; 95% confidence interval, 0.96 to 1.20). During the 72 hours after the first surfactant dose, the average FIO2 (+/- SEM) was 0.50 +/- 0.01 for Exosurf and 0.42 +/- 0.01 for Survanta (difference, 0.08; 95% confidence interval, 0.05 to 0.11); the average MAP (+/- SEM) was 7.64 +/- 0.21 cm H2O for Exosurf and 6.93 +/- 0.21 cm H2O for Survanta (difference, 0.71 cm H2O; 95% confidence interval, 0.13 to 1.29 cm H2O). There was no difference between the groups in the incidence of other neonatal morbidities or in the duration of hospitalization, assisted ventilation, or supplemental oxygen administration. CONCLUSION: We found no difference between treatment groups in the incidence of death or bronchopulmonary dysplasia, although we did observe a difference in the initial response to treatment as measured by FIO2 and MAP.
Assuntos
Produtos Biológicos , Álcoois Graxos/uso terapêutico , Fosforilcolina , Polietilenoglicóis/uso terapêutico , Surfactantes Pulmonares/uso terapêutico , Síndrome do Desconforto Respiratório do Recém-Nascido/tratamento farmacológico , Combinação de Medicamentos , Álcoois Graxos/administração & dosagem , Feminino , Humanos , Recém-Nascido , Masculino , Polietilenoglicóis/administração & dosagem , Surfactantes Pulmonares/administração & dosagem , Síndrome do Desconforto Respiratório do Recém-Nascido/fisiopatologia , Mecânica Respiratória , Resultado do TratamentoRESUMO
To determine the impact of very low birth weight (VLBW) on medical outcomes during childhood, we compared the health of 249 VLBW children born from 1977 through 1979 with that of 363 normal birth weight (NBW) control children at 8 years of age. Measures included the rates of specific illnesses, surgical procedures and accidents, growth, and other physical findings. The number of medical conditions and surgical procedures was significantly greater in the VLBW children than in the NBW control children. Eighteen percent of VLBW versus 5% of NBW children had had respiratory conditions (p < 0.001), mainly before 3 years of age. Surgical procedures were more common both before and after 3 years of age, but accidents occurred with similar frequency. The VLBW children had significantly lower weight, height, and head circumference and more minor physical stigmata. Thus medical illness, surgical interventions, and poor growth attainment are part of the ongoing morbidity of VLBW children during childhood.
Assuntos
Recém-Nascido de Baixo Peso , Morbidade , Acidentes , Pressão Sanguínea , Criança , Pré-Escolar , Feminino , Seguimentos , Crescimento , Humanos , Lactente , Recém-Nascido , Masculino , Procedimentos Cirúrgicos OperatóriosRESUMO
To determine whether the level of fibronectin in lung secretions correlates with the severity of lung injury or with the development of bronchopulmonary dysplasia, or both, serial tracheal aspirate samples were collected from 32 preterm infants with severe respiratory distress syndrome. Levels of total fibronectin, cellular fibronectin, plasma fibronectin, albumin, and secretory component of IgA (SC) were determined for the first 1 to 2 weeks of life in the 14 infants who recovered without pulmonary sequelae, and for weeks 1 to 4 in the 18 infants in whom bronchopulmonary dysplasia developed. Secretory component was chosen as the reference protein because its concentration in lung secretions is minimally influenced by capillary leak and does not vary with gestational or postnatal age. Albumin/SC and plasma fibronectin/SC ratios in tracheal aspirates were significantly higher (p less than 0.05) during the first 2 weeks of life in infants in whom bronchopulmonary dysplasia developed, suggesting greater capillary permeability in these infants. Cellular fibronectin/SC ratios in aspirates from infants with bronchopulmonary dysplasia were also significantly higher in the first 2 weeks, 9.0 +/- 1.7 and 7.4 +/- 2.0 micrograms/microgram SC in weeks 1 and 2, respectively, in comparison with values from infants without bronchopulmonary dysplasia, 1.6 +/- 0.4 and 1.1 +/- 0.8 micrograms/microgram SC (p less than 0.01), suggesting increased synthesis of fibronectin in the lungs of infants with subsequent bronchopulmonary dysplasia. Elevated levels of both plasma and cellular fibronectin in tracheal aspirate samples may provide an early index of the severity of lung injury in infants with severe respiratory distress syndrome.
Assuntos
Líquido da Lavagem Broncoalveolar/química , Displasia Broncopulmonar/metabolismo , Fibronectinas/análise , Síndrome do Desconforto Respiratório do Recém-Nascido/metabolismo , Albuminas/análise , Displasia Broncopulmonar/etiologia , Feminino , Fibronectinas/biossíntese , Fibronectinas/sangue , Humanos , Imunoglobulina A Secretora/análise , Recém-Nascido , Masculino , Síndrome do Desconforto Respiratório do Recém-Nascido/complicaçõesRESUMO
We studied the occurrence of necrotizing enterocolitis in 2681 very low birth weight infants during an 18-month period to characterize the biodemographic and clinical correlates. Proven necrotizing enterocolitis (Bell stage II and beyond) occurred in 10.1% of study infants; necrotizing enterocolitis was suspected in 17.2% of study infants. Positivity of blood cultures was related to necrotizing enterocolitis staging. The mortality rate increased only for stage III necrotizing enterocolitis (54% died). Logistic regression identified medical center of birth, race, gender, birth weight, maternal hemorrhage, duration of ruptured membranes, and cesarean section as significant risk factors. For one center the odds ratio was 3.7, whereas for another center it was only 0.3. For black boys, the odds ratio was 2.3 relative to nonblack boys; for girls, race did not affect prevalence of necrotizing enterocolitis. Age at onset was related to birth weight and gestational age. Intercenter differences in necrotizing enterocolitis prevalence were related to time required to regain birth weight and other indicators of fluid management. Gram-positive organisms predominated in positive blood cultures for stage I and II necrotizing enterocolitis; enteric bacteria were isolated more frequently in infants with stage III disease. We conclude that necrotizing enterocolitis prevalence varies greatly among centers; this may be related to early clinical practices of neonatal care.
Assuntos
Enterocolite Pseudomembranosa/fisiopatologia , Recém-Nascido de Baixo Peso , Peso ao Nascer , População Negra , Enterocolite Pseudomembranosa/epidemiologia , Enterocolite Pseudomembranosa/mortalidade , Feminino , Bactérias Gram-Positivas/isolamento & purificação , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Masculino , Estudos Multicêntricos como Assunto , Cuidado Pré-Natal , Prognóstico , Fatores de Risco , Fatores SexuaisRESUMO
To evaluate the use of intravenously administered immune globulin (IVIG) for prevention of sepsis in preterm infants, we administered IVIG in a protocol designed to maintain a therapeutic serum "target level" of 700 mg/dl. The 200 patients who were eligible for the study (600 to 2000 gm birth weight) were monitored throughout their initial hospitalization. Of these, 115 patients were randomly assigned in a double-blind, controlled trial to treatment and placebo groups. The remaining 85 infants were not randomly assigned to a group, by parental request, but were followed and analyzed separately. In one patient who received IVIG, transient tachycardia and a decrease in blood pressure developed during an infusion; resolution occurred promptly after the infusion was discontinued. No persistent hepatic or renal abnormalities were noted in either the IVIG- or the placebo-treated group. There were seven episodes of sepsis in the placebo group and nine in the group whose parents refused consent to the study. No infant who received IVIG acquired nosocomial sepsis (p less than 0.01). All patients in the placebo group in whom sepsis developed had serum IgG levels less than 400 mg/dl at the time sepsis developed. Serum IgG levels were maintained near 700 mg/dl in patients who received IVIG. These data indicate that administration of sufficient IVIG to maintain target serum IgG levels throughout hospitalization may decrease the incidence of nosocomial sepsis in preterm infants.
Assuntos
Infecção Hospitalar/prevenção & controle , Imunização Passiva , Recém-Nascido de Baixo Peso/imunologia , Método Duplo-Cego , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Infusões Intravenosas , Masculino , Projetos Piloto , Distribuição AleatóriaRESUMO
The effects of frequency, tidal volume, and inadvertent positive end-expiratory pressure (PEEP) on CO2 elimination were studied in rabbits during high-frequency jet ventilation by measuring CO2 concentration of expired gas using a mass spectrometer. Increasing tidal volume augmented CO2 elimination (P less than 0.01 to 0.001) at each frequency, but when larger tidal volumes were associated with high inadvertent PEEP, CO2 elimination decreased despite the increase in minute ventilation. For constant minute ventilation, CO2 elimination decreased with increasing frequencies. Occurrence of inadvertent PEEP was related to increases in both frequency and tidal volume. If PEEP was controlled, no decrease in CO2 elimination was observed at the larger tidal volume. When PEEP was controlled, changes in tidal volume explained 67.1% to 95.4% of the variance in CO2 elimination not attributable to frequency. Frequency explained very little additional variance (0.1% to 13.8%). CO2 elimination comparable to estimated CO2 production occurred when tidal volumes equal to or smaller than the equipment dead space were used. We conclude that although tidal volume has a greater effect than frequency on CO2 elimination, mechanisms of gas exchange other than bulk gas transport occur during high-frequency jet ventilation.
Assuntos
Dióxido de Carbono/análise , Respiração Artificial/métodos , Análise de Variância , Animais , Espectrometria de Massas , Respiração com Pressão Positiva , Troca Gasosa Pulmonar , Coelhos , Volume de Ventilação Pulmonar , Capacidade VitalRESUMO
To evaluate the influence of postnatal maturation on oral breathing, we measured nasal and oral ventilation during sleep and the ventilatory response to nasal occlusion in 11 preterm infants. Studies were repeated at 31-32, 33-34, and 35-36 weeks postconceptional age. Premature infants had rare episodes of spontaneous oronasal breathing during sleep. The frequency of oral breathing in response to nasal occlusion increased with advancing postconceptional age, from 8% +/- 8% at 31-32 weeks to 26% +/- 18% at 33-34 weeks and 28% +/- 33% at 35-36 weeks. Oral breathing in preterm infants, unlike that in term infants, was characterized by intermittent airway obstruction leading to a significant decrease in respiratory rate, tidal volume, minute ventilation, and tcpo2 (P less than 0.005). When inspiratory (Rl) and expiratory (RE) resistances during nasal and oral breathing were compared, Rl increased from 41 +/- 30 to 234 +/- 228 (P less than 0.004) and RE from 62 +/- 16 to 145 +/- 43 cm H2O X L-1 X sec (P less than 0.004). The ability of preterm infants to use the oral route of breathing thus increases with advancing postnatal maturation, but its effectiveness may remain limited by high oral airway resistance.
Assuntos
Crescimento , Recém-Nascido Prematuro , Respiração , Feminino , Humanos , Recém-Nascido , Masculino , Boca , Nariz , Sono/fisiologiaRESUMO
Newborn infants are considered obligate nasal breathers, hence dependent on a patent nasal airway for ventilation. The conditions under which oral breathing could occur and the contribution of oral ventilation to total ventilation were studied in 30 healthy term infants (aged 1 to 3 days). Nasal and oral airflow were measured using two resistance-matched pneumotachometers, and heart rate, tcPO2, etCO2, and sleep state were continuously recorded. In three of 10 infants studied in undisturbed sleep, spontaneous oronasal breathing was noted during both active and quiet sleep (mean duration 19 +/- 25 minutes), the distribution of tidal volume being 70% +/- 12% nasal and 30% +/- 12% oral. Episodes of oronasal breathing were also observed after crying in six infants (mean duration 21 +/- 19 seconds). In an additional 20 infants, multiple 15-second end-expiratory nasal occlusions were performed; eight (40%) of these infants initiated and sustained oral breathing in response to nasal occlusion. Respiratory rate, tidal volume, heart rate, and tcPO2 did not change when oral breathing occurred in response to nasal occlusion, although minute ventilation decreased from 265 to 199 ml/min/kg (P less than 0.05). These results demonstrate that newborn infants may use the oral airway for ventilation, both spontaneously and in response to complete nasal occlusion.
Assuntos
Respiração Bucal/fisiopatologia , Respiração , Obstrução das Vias Respiratórias/fisiopatologia , Choro/fisiologia , Humanos , Recém-Nascido , Nariz/fisiologia , Nariz/fisiopatologia , Respiração Artificial , Sono/fisiologiaRESUMO
Using a crossover study design, we compared a system of high-frequency jet ventilation with appropriate humidification to pressure-limited conventional ventilation in 12 preterm infants with a birth weight of 1.9 +/- 0.6 kg and gestational age of 32 +/- 2 weeks who had severe respiratory distress syndrome. After a control period of conventional ventilation, high-frequency jet ventilation was administered for 1 to 3 hours at a constant rate (250/min) and inspiratory to expiratory time (1:3 or 1:4) in the same fraction of inspired oxygen as during conventional ventilation. Average peak inspiratory pressure decreased from 29 +/- 3 cm H2O during conventional ventilation to 20 +/- 4 cm H2O during high-frequency jet ventilation (P less than 0.001), whereas positive end expiratory pressure was unchanged, resulting in a reduction in mean airway pressure from 14 +/- 3 to 10 +/- 2 cm H2O (P less than 0.001). There was a simultaneous decrease in PaCO2 (39 +/- 4 to 34 +/- 4 mm Hg, P less than 0.01), but PaO2 did not change. These data indicate that short-term high-frequency jet ventilation maintains gas exchange in infants with respiratory distress syndrome despite a lower PIP and Paw, and results in smaller airway pressure swings than during conventional ventilation. Thus, high-frequency jet ventilation may offer hope for reducing barotrauma in this population.
Assuntos
Troca Gasosa Pulmonar , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório do Recém-Nascido/terapia , Gasometria , Pressão Sanguínea , Feminino , Frequência Cardíaca , Humanos , Recém-Nascido , Masculino , Pressão , Respiração Artificial/efeitos adversosRESUMO
Hypertension (blood pressure greater than 70 mm Hg on three days) was noted in 1.2% of all neonatal admissions to the intensive and intermediate care nurseries. During this investigation of neonatal hypertension, a retinopathy identical to that seen in hypertensive adults was noted. Indirect ophthalmoscopy was performed in 21 neonates with elevated blood pressure. Eleven of these patients demonstrated some or all of the following abnormalities: increased ratio of venous to arterial caliber, vascular tortuosity (including arteriovenous crossing changes), superficial and deep hemorrhages, and exudates. These findings appeared to resolve after control of the hypertension. The specificity of this constellation of lesions for hypertensive retinopathy and their possible clinical significance are explained in light of what is known about hypertensive retinopathy in adults.
Assuntos
Hipertensão/complicações , Doenças Retinianas/etiologia , Exsudatos e Transudatos , Humanos , Recém-Nascido , Oftalmoscopia , Doenças Retinianas/patologia , Hemorragia Retiniana/etiologia , Vasos Retinianos/patologiaRESUMO
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.
Assuntos
Ingestão de Líquidos , Recém-Nascido Prematuro , Respiração , Feminino , Humanos , Recém-Nascido , Capacidade Inspiratória , Masculino , Postura , Volume de Ventilação PulmonarRESUMO
Necrotizing enterocolitis has been associated with a variety of perinatal problems which have been purported to be risk factors predisposing the neonate to NEC. The present investigation compares the perinatal histories of 48 low-birth-weight infants (less than 1,500 gm) with NEC to those of 553 high-risk infants of equivalent birth weight who did not have NEC but who were present in the nursery during a four-year observation period. The two populations were equivalent with regard to maternal factors such as socioeconomic status, education, race, and age. Both the antenatal and intrapartum risk scores were similar, as were the position of presentation and mode of delivery. The incidence of pre-eclampsia, prolonged rupture of the membranes, and placenta previa was also equivalent. Birth weight and gestational age were identical, as well as intrauterine growth retardation and low Apgar scores. The placement of umbilical artery catheters or the performance of exchange transfusions were not more frequent among patients with NEC. Infants who developed NEC demonstrated significantly different incidences of only three variables. Mothers of these infants were usually married, and their infants had less respiratory distress syndrome; the only adverse factor present more frequently was abruptio placenta. These data raise further questions concerning the significance of previously reported risk factors of NEC.