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Biomedical subjects

R B Cotton

Publications and source records attributed to R B Cotton.

At least 37 records · Page 2Linked to original sources
PubMed1988

Measurement of tidal volume during high frequency ventilation by impedance plethysmography.

Electrical impedance plethysmography was evaluated in lambs as a method of measuring tidal volume (VT). Over tidal volumes ranging from 15 to 414% of estimated dead space, and frequencies of 300 to 1000 breaths/min, correlation between VT measured by the impedance technique and VT measured by whole-body plethysmography was 0.98. Above 600 breaths/min, the correlation between the two methods was 0.94. Independent calibration of the impedance technique using a pneumotachograph at conventional rates of ventilation yielded absolute values of VT which closely corresponded to values obtained with the whole-body plethysmograph (slope = 1.05, intercept = 1.4 ml, r = 0.99). These results support the potential utility of impedance plethysmography in clinical applications of high frequency ventilation.

Animals↗
PubMed1987

Altered early left ventricular diastolic cardiac function in the premature infant.

Developmental changes in diastolic ventricular function were assessed in 31 premature infants and in 10 normal-term infants. They were studied during the first 72 hours of life using instantaneous rates of change of left ventricular (LV) cavity dimension, derived from M-mode echocardiography. Maximal velocity of lengthening of the LV cavity was significantly lower in premature infants (38 +/- 7 mm/s) than in term infants (88 +/- 15 mm/s). This variable increased with increasing maturity over the 4 gestational age groups evaluated (r = 0.87). This index normalized for instantaneous LV dimension was lower in the most immature infants (4.5 +/- 1 s-1) than in term infants (6.8 +/- 2 s-1). Eight of the premature infants were studied serially at 1, 3 and 7 days of age. Maximal velocity of lengthening divided by stroke dimension improved from 12.9 +/- 2 s-1 at 1 day of age to 16.5 +/- 3 s-1 at 7 days. These results suggest depressed early diastolic function in premature infants.

Diastole↗
PubMed1987

The relationship of symptomatic patent ductus arteriosus to respiratory distress in premature newborn infants.

When left-to-right shunting through the ductus arteriosus contributes to respiratory distress of the newborn premature infant, the condition is termed generally as symptomatic PDA. The physiologic setting of this condition and its definition are considered first in this article. Subsequent sections detail the incidence of symptomatic PDA and predisposing risk factors, followed by a discussion of its clinical presentation, diagnosis, and management.

Ductus Arteriosus, Patent↗
PubMed1987

Is chronic lung disease in low birth weight infants preventable? A survey of eight centers.

Chronic lung disease in prematurely born infants, defined as the need for increased inspired oxygen at 28 days of age, was thought to be more common in some institutions than in others. To test this hypothesis, we surveyed the experience in the intensive care nurseries at Columbia and Vanderbilt Universities, the Universities of Texas at Dallas, Washington at Seattle, and California at San Francisco, the Brigham and Women's Hospital in Boston, Texas Children's Hospital in Houston, and Mt Sinai Hospital in Toronto. The survey included 1,625 infants with birth weights of 700 to 1,500 g. We confirmed the relationship of risk to low birth weight, white race, and male sex. Significant differences in the incidence of chronic lung disease were found between institutions even when birth weight, race, and sex were taken into consideration through a multivariate logistic regression analysis. Columbia had one of the best outcomes for low birth weight infants and the lowest incidence of chronic lung disease.

Bronchopulmonary Dysplasia↗
PubMed1986

Systemic production of prostacyclin and thromboxane A2 does not correlate with patency of the ductus arteriosus in very low birth weight infants.

Urinary excretion of prostacyclin and thromboxane metabolites (2,3-dinor-6-ketoprostaglandin F1 alpha, thromboxane B2, and 2,3-dinor-thromboxane B2) as indices of systemic biosynthesis was prospectively determined in nine premature infants during the first 10 days of life, by gas chromatography-mass spectrometry. The patients ranged in gestational age from 27 to 29 weeks and in birth weight from 720 to 980 gm. Four infants developed symptomatic patent ductus arteriosus (PDA). Excretion of all metabolites exceeded adult values on the basis of body surface area at birth, reached a maximum on the fourth day of life, was related to urine output, and did not distinguish patients with and without symptomatic PDA. We conclude that neither circulating prostacyclin nor thromboxane A2 contribute significantly to the pathophysiology of symptomatic PDA in very low birth weight infants.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Ductus closure in preterm infants. Effects on cerebral hemodynamics.

Intracranial arterial blood flow velocities were studied before and after ductus closure by surgery (n = 8) and indomethacin (n = 10) in very low birth weight infants. Blood flow velocities were measured non-invasively through the fontanel with a pulsed Doppler velocimeter. Ligation of the ductus was associated with a 62% increase in mean flow velocity 24 hours after surgery, mainly secondary to increased diastolic flow velocity. Indomethacin (0.2 mg/kg i.v.) induction of ductus constriction was associated with a 36% decrease of mean flow velocity one hour after administration. At 24 hours, the intracranial blood flow velocity had returned to the pretreatment level but was still significantly lower than after ligation. Ductus closure is associated with marked changes in cerebral hemodynamics. Ligation causes increased arterial blood flow velocities and indomethacin administration seems to reduce blood flow velocities to the brain.

Blood Flow Velocity↗
PubMed1985

Necrotizing entercolitis. Variables associated with the severity of disease.

The medical records of 51 inborn infants with necrotizing enterocolitis (NEC) were studied to determine factors that may contribute to the severity of NEC. In contrast to infants requiring only medical intervention, those with severe disease requiring a surgical procedure were less likely to have a history of a symptomatic patent ductus arteriosus (14% v 45%); they also required fewer days of antibiotic therapy (three v five) and fewer days of endotracheal intubation (0.5 v three). They were fed earlier (two days v four days). The diagnosis was made at a younger age in infants needing surgery (6.5 days v 14 days). These data indicate that infants with minimal neonatal morbidity may be at risk for severe NEC, which results in bowel necrosis.

Anti-Bacterial Agents↗
PubMed1985

Complication of insulin-dependent diabetic pregnancies by preeclampsia and/or chronic hypertension: analysis of outcome.

The significance of hypertensive complications of insulin-dependent diabetic pregnancies (IDDP) has not been well examined since the early reports of Pedersen, which demonstrated an increased risk of neonatal death in women with pregnancy induced hypertension (PIH). To assess the effect of both PIH and chronic hypertension (CH) on outcome of IDDP managed using contemporary obstetrical and diabetic management, we reviewed the records of all 199 IDDP delivered at our institution over a 7-year period. Patients were classified as having PIH (Group 1, n = 37), CH (Group 2, n = 18) or both (Group 3, n = 4) on the basis of standard clinical criteria. All other IDDP were placed in the control group (Group 4, n = 140). Comparing all groups, significant differences were found for maternal age (P less than .0001) and distribution among White's Classes (P less than .0001). There was no significant difference in estimated gestational age (EGA) at delivery, birthweight, Apgar scores, hypoglycemia, hyperbilirubinemia, or congenital anomalies. Intrauterine fetal death (IUFD) was no more common in Groups 1, 2 or 3 than in Group 4; however, IDDP with CH were significantly more likely to have had previous stillbirths than IDDP with PIH (P = .011) or control IDDP (P = .017). Contrary to common clinical belief, the "stress" of CH and PIH did not offer protection to the newborn in the development of RDS or HMD. In fact, Group 3 infants had a higher rate of HMD than control infants (P = .024).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Early experience with illuminated endotracheal tubes in premature and term infants.

A major problem in the care of premature and other newborn infants is obtaining and maintaining correct position of an endotracheal tube. Improper placement of the distal tip of the endotracheal tube above the larynx or below the carina is a life-threatening hazard that not only impairs ventilation, but also may result in serious pulmonary complications such as lobar atelectasis and air leak. This problem was addressed by testing the hypothesis that a light source at the end of the endotracheal tube could be seen on the neck and chest and that, therefore, the endotracheal tube could be positioned and repositioned without radiologic guidance. The validity of this concept was confirmed in animals using a rigid bronchoscope light source and conventional endotracheal tubes. Then an endotracheal tube in which a fiberoptic strand was incorporated in the wall and which terminated near the tip of the tube was used. The illuminated endotracheal tube was used 33 times in 25 infants. This technique has been shown to provide a safe method (not requiring ionizing radiation) for positioning of the endotracheal tube by virtue of external visualization of a circle of light on the surface of the baby. This system will not permit differentiation of tracheal from esophageal intubation.

Bronchoscopes↗
PubMed1984

Recurrence of symptomatic patent ductus arteriosus in extremely premature infants, treated with indomethacin.

The administration of a single intravenous injection of indomethacin was followed by a major constrictive effect on the ductus in 36 of 42 very-low-birth-weight (less than or equal to 1000 gm) infants with symptomatic patent ductus arteriosus (PDA). In 26 of the 36 responders, the effect was sustained; symptomatic PDA recurred in the remaining 10. Infants who experienced a recurrence of symptomatic PDA had lower birth weights and had received indomethacin at an earlier postnatal age than did infants with a sustained effect. These results may be explained by differences in the production and clearance of prostaglandins or in the sensitivity of the ductus to prostaglandin effects between infants with a recurrence and infants with sustained constriction of PDA.

Ductus Arteriosus, Patent↗
PubMed1984

Continuing neonatal morbidity in infants of women with class A diabetes.

Despite having implemented rigorous glucose control for women with gestational diabetes early in the third trimester, we found excessive morbidity among the neonates of these women. To accurately assess the risk of newborn complications, we did a five-year review (1977 to 1981) of infants of class A diabetic mothers to determine the incidence and scope of morbidity in these infants. Fifty-one infants of class A mothers were identified (group 1) and randomly matched with 102 infants of nondiabetic mothers (group 2). The distribution of morbidity between the two groups was as follows: hypoglycemia 9/51 (18%) vs 0/102 (P less than .001); birth injuries 4/51 (8%) vs 1/102 (2%) (P less than .05); pulmonary edema 3/51 (6%) vs 0/102 (P less than .05); respiratory distress 4/51 (8%) vs 7/102 (7%) (NS); macrosomia 18/51 (35%) vs 23/102 (23%) (NS); and hyperbilirubinemia 3/51 (6%) vs 8/102 (8%) (NS). There were two fetal deaths and three infants with major congenital anomalies among the diabetic pregnancies compared to none from the nondiabetic pregnancies. Compared to insulin-dependent diabetes, class A diabetes is accompanied by relatively mild metabolic disturbances in the mother. On the other hand, the infant of a mother with class A diabetes appears to be at risk for serious and life-threatening complications, both before and after birth. These results raise the question of whether earlier identification, subsequent meticulous diabetic management, and altered timing of delivery might reduce the complications experienced by these infants.

Abnormalities, Multiple↗
PubMed1983

Sonographic depiction of changes in ventricular size associated with repeated ventricular aspirations.

Serial real-time cranial sonography was performed on 11 preterm neonates who had demonstrated progressive posthemorrhagic ventricular dilatation and were subjected to repeated ventricular aspirations. Changes in ventricular size were correlated with gestational age, birth weight, and extent and location of the intracranial hemorrhage, as well as the timing, frequency, and location of the ventricular aspirations and the average amount of cerebrospinal fluid removed. The sizes of both lateral ventricles of each neonate were measured and the occurrence of sequelae related to repeated ventricular aspiration was examined. Eleven ventricles diminished in size, eight increased, and there was no change in three. Two neonates had bleeding near the aspiration sites. It is concluded that repeated aspiration can be associated with a diminution in ventricular size in some neonates. It is recommended that alternative methods of treatment, such as serial lumbar puncture or external ventriculostomy, be attempted prior to initiating repeated ventricular aspirations.

Birth Weight↗
PubMed1982

Detection of intraventricular hemorrhage (IVH) by transcephalic impedance (TCZ) in premature infants.

Transcephalic impedance was measured serially in 45 preterm infants less than 1500 g birth weight in order to test the method for the early detection of intraventricular hemorrhage. TCZ increased in all seventeen (38%) infants who developed IVH diagnosed by CT-scan or autopsy. Five of 8 infants monitored 4-8 weeks following confirmed IVH developed hydrocephalus documented by repeat CT-scans; all 5 were discovered early by the TCZ-method 2-3 weeks before physical findings or an increasing head circumference indicated the possibility of hydrocephalus. TCZ appears to be a useful non-invasive clinical guide to the occurrence and course of IVH in the newborn.

Brain↗
PubMed1982

A quantitative model for hyaline membrane disease.

A model based on the course of 31 infants with uncomplicated hyaline membrane disease is described. Based on data collected over the first 12 hr of life, it predicts the course of an infant for the next 60 hr, and estimates the outcome in terms of length of oxygen requirement and assisted ventilation. For the construction of the model, right-to-left intra- and extra-pulmonary shunting, expressed as venous admixture, was considered as the principal mechanism of hypoxemia in hyaline membrane disease and mean applied proximal airway pressure was used to quantify management. The model provides an objective estimate of severity early in the course of disease, uses variables routinely available in an intensive care unit, and its use would strengthen the interpretation of clinical studies in which the comparability of experimental and control groups is critical.

Humans↗
PubMed1981

Pharmacokinetics of indomethacin in the neonate. Relation of plasma indomethacin levels to response of the ductus arteriosus.

To identify factors affecting the efficacy of indomethacin in closing symptomatic patent ductus arteriosus (PDA), we studied the pharmacokinetics of intravenous indomethacin, 0.2 mg per kilogram of body weight, in 35 premature infants with symptomatic PDA. Most infants responded to indomethacin with ductus constriction. Indomethacin infusions that were ineffective (seven doses in six patients) were associated with significantly faster clearance, a shorter half-life, and lower plasma levels (p less than 0.05). Six infants had later reopening of the ductus. All six received indomethacin in the first postnatal week; they could not be distinguished from infants with permanent closure on the basis of indomethacin kinetics, but they were of low gestational age. There was a 20-fold variation in plasma indomethacin levels 24 hours after a dose. In view of this variation and the relation between plasma levels and ductus constriction, we suggest that measurement of the plasma indomethacin level could be of value in infants with no response to a first dose.

Ductus Arteriosus↗
PubMed1981

Early prediction of symptomatic patent ductus arteriosus from perinatal risk factors: a discriminant analysis model.

A scoring system based on discriminant analysis was devised to predict, within 24 hours after birth, whether or not a premature infant will subsequently develop a symptomatic PDA. Five risk factors including birth weight, the diagnosis of hyaline membrane disease, intrauterine growth retardation, acute perinatal stress, and treatment with distending airway pressure were reduced to a discriminant score which separated infants with symptomatic PDA from infants without symptomatic PDA. Based on this score, the likelihood that an individual infant would later develop symptomatic PDA could be expressed as a probability function. When applied prospectively, this score predicted the correct outcome of 80% of infants in a test population. This predictive model should be useful in clinical trials and other applications requiring a quantitative expression of risk for developing symptomatic ductus shunting.

Birth Weight↗