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Biomedical subjects

M A Simmons

Publications and source records attributed to M A Simmons.

At least 73 records · Page 4Linked to original sources
PubMed1979

Results of the intensive perinatal management of very-low-birth-weight infants (501 to 1,500 grams).

In January 1975 at the University of Colorado Medical Center, a program of intensive intrapartum and neonatal care went into effect for all infants with expected birth weights of over 600 gm. Data are presented on the 187 infants weighing 501 to 1,000 gm born in 1975 to 1976. The 70 infants weighing 501 to 1,000 gm had a perinatal mortality of 65% and a neonatal mortality of 55%. The perinatal mortality of the 117 infants weighing 1,001 to 1,500 gm was 25% and the neonatal mortality 20%. Among the 501- to 1,000-gm infants, cesarean section for delivery of abnormal presentations resulted in a lower perinatal mortality than did vaginal delivery. Apgar scores were predictive of an improved chance of survival, but scores of three or less even at five minutes were associated with a 25% survival rate. Of those infants who did not survive the neonatal period, over 70% had died by 48 hours of life. These results were achieved without the use of beta-mimetic tocolytic agents to inhibit labor or long-acting corticosteroids to enhance pulmonary maturation. The improved survival of the infants weighing 1,500 gm or less when compared with infants of similar weights in preceding years is attributed to more intensive perinatal management of these mothers and their very-low-birth-weight infants.

Birth Weight↗
PubMed1979

Placental transfer of glucose.

The rates of glucose transfer from maternal blood to pregnant uterus and from placenta to fetus were measured in eight sheep at spontaneously occurring glucose concentrations (control state) and while the fetus, the mother, or both were receiving a constant infusion of glucose. In addition two fetuses received insulin infusions. In the control state the net glucose flux from placenta to fetus was only 27 +/- 2.6% (SEM) of the net flux from the uterine circulation to the pregnant uterus. An empirical equation describing the relationship between placental glucose transfer and arterial plasma glucose concentrations was derived from the data and compared with equations constructed on the basis of methematical models of placental function. This analysis indicates that: (1) placental glucose transfer is mediated by carriers with Km approximately equal to 70 mg/dl; (2) the rate of glucose transfer from mother to fetus is limited primarily by the transport characteristics and glucose consumption rate of the placenta; (3) under normal conditions of placental perfusion, glucose transfer is approximately 15% less than it would be if placental blood flows were infinitely large.

Animals↗
PubMed1978

Low positioning of umbilical-artery catheters increases associated complications in newborn infants.

We performed a randomized prospective study of the effect of placement position of umbilical-artery catheters on complication rates in high-risk newborn infants. A higher complication rate (31 of 40 vs. 13 of 33) (P less than 0.005) occurred in the group with the catheter tip at the third to fourth lumbar segment, as compared to those with the tip at the seventh to eighth thoracic segment, owing to more episodes of blanching and cyanosis of the extremities. There was no difference between groups in the rate of complications requiring catheter removal. Aortography revealed thrombosis in 21 of 23 patients studied, but there was no clinical evidence of impaired circulation. In retrospect, we found that, independently of catheter position, administration of antibiotics through the catheter was associated with an increased rate of complications (63 vs. 20 per cent). Umbilical-artery catheterization entails potential risks regardless of the position of the catheter; placement of the catheter with its tip at the seventh to eighth thoracic segment may be associated with fewer complications than at lower positions.

Amino Acids↗
PubMed1978

The silent ductus arteriosus.

Preterm infants at risk of developing a patent ductus arteriosus were followed sequentially by physical examination, echocardiographic determinations of the LA/AO ratio, and chest roentgenograms. The results show that a significant number of infants who have no clinical signs or symptoms of a PDA have large left-to-right shunts. The presence of this shunt was suggested by acute increase in left atrial size by ECHO determination and confirmed by retrograde single-film aortography. Clinical signs and symptoms often developed several days after documentation of the left-to-right shunt.

Aortography↗
PubMed1978

Insulin effect on fetal glucose utilization.

Insulin infused into a sheep fetus over a 3-hr period at the rate of approximately 0.24 U.kg-1.h-1 increased fetal glucose uptake (utilization) from 4.4 +/- 0.7 mg.min-1.kg-1 to 6.9 +/- 0.9 mg.min-1.kg-1 as compared to a noninsulin control period. Insulin administration did not alter fetal oxygen consumption (8.6 +/- 0.7 ml.min-1.kg-1 vs. 7.7 +/- 0.7 ml.min-1.kg-1), umbilical blood flow (220 +/- 1 ml.min-1.kg-1 vs. 209 +/- 16 ml.min-1.kg-1), or the placental clearances of antipyrine (114 +/- 7 ml.min-1.kg-1 vs. 109 +/- 8ml.min-1.kg-1) and urea (24.5 +/- 2.2 ml.min-1.kg-1 vs. 25.0 +/- 2.1 ml.min-1.kg-1). Fetal plasma glucose concentration fell significantly (0.22 +/- 0.01 mg.ml-1 to 0.16 +/- 0.01 mg.ml-1) during insulin infusion. The insulin effect on fetal glucose uptake occurred over a range of maternal glucose concentrations (0.32 leads to 0.78 mg.ml-1), which were not altered by the infusion of insulin in the fetal compartment. Insulin has a specific effect on increasing fetal glucose uptake and utilization.

Animals↗
PubMed1978

Middle ear effusions in neonates.

Suppurative middle ear effusions (MEE) have been shown to occur commonly in neonates. In spite of this, otoscopy is not routinely performed on septic infants in the neonatal intensive care unit (ICU). This is clinically significant since unrecognized suppurative MEE may act as a focus for dissemination of bacteria into the circulation and/or central nervous system (CNS). We have completed a prospective study in an attempt to define the prevalence, bacteriology, and response to therapy of MEE in neonates. To facilitate this, the normal micro-otsocopic appearance of the newborn TM was established by systematically examining 50 normal infants under 24 hours old. MEE was present in 30% of 125 consecutively examined infants in the neonatal ICU. Bacteriologic data are drawn from tympanocentesis performed on 34 neonates. Nasotracheal intubation of longer than seven days is highly associated with suppurative MEE. Suppurative MEE in the neonatal ICU is often refactory to treatment and may require prolonged therapy and repeated tympanocentesis.

Animals↗
PubMed1978

Otitis media in the neonatal intensive care unit.

Thirty-eight of 125 premature infants who were hospitalized in a neonatal intensive care unit (NICU) had abnormal tympanic membrane mobility compatible with otitis media. Twenty-five of these 38 had received antibiotics within one week of otoscopic examination and were considered to have either serous otitis or partially treated bacterial otitis media; tympanocentesis was not performed in them. Tympanocentesis was performed in the remaining 13 infants who had not received antibiotics. Bacterial otitis media was confirmed in ten of the 13. Either staphylococcal (six cases) or Gram-negative enteric organisms (four cases) were isolated in cultures obtained by tympanocentesis in these cases. The four cases of Gram-negative infections occurred in infants within six weeks of birth. Nasotracheal intubation for more than seven days was significantly correlated with impaired tympanic membrane mobility compatible with otitis media. Otitis media occurs frequently among premature infants who are hospitalized in an NICU, and it should be looked for in any infant in whom sepsis is clinically suspected.

Cross Infection↗
PubMed1977

Selective bronchial intubation for the treatment of severe localized pulmonary interstitial emphysema in newborn infants.

As an alternative to lobectomy and in order to preserve lung tissue which may be potentially functional we have selectively intubated the right main bronchus in four infants 12 to 25 days old with severe, pulmonary interstitial emphysema of the left lung. In each case the localized hyperinflation disappeared within 5 to 48 hours of contralateral selective bronchial intubation. The duration of SBI was 1.5 to 5 days. Three patients benefited from the procedure; there were no serious complications. We propose that SBI should be tried in infants with severe, localized PIE which has caused mediastinal shift, compressive atelectasis, and respiratory acidosis requiring mechanical ventilation despite vigorous pulmonary therapy and usual supportive measures.

Bronchi↗
PubMed1976

Combined obstetric and pediatric approach to prevent meconium aspiration syndrome.

Routine intrapartum pharyngeal suctioning with a DeLee catheter of infants with meconium staining has significantly reduced the incidence and severity of meconium aspiration syndrome (MAS). There have been no adverse sequelae to this procedure, which is carried out while the infant's head is on the perineum, prior to the onset of respirations. Routine suctioning of the trachea under direct vision after delivery is rarely necessary but should be done if meconium is visualized at the vocal cords. Tracheobronchial lavage with saline may add to the respiratory morbidity. No deaths or severe cases of MAS have occurred since institution of the obstetric suctioning procedure.

Female↗