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T E Wiswell

Publications and source records attributed to T E Wiswell.

At least 19 recordsLinked to original sources
PubMed1992

Removing meconium from infant tracheae. What works best?

OBJECTIVE: At least nine mechanical devices are available for suctioning the tracheae of meconium-stained newborns. To our knowledge, the efficacy of these devices, as well as various suction pressures and patterns, has not been previously compared. We performed this investigation to assess these variables. DESIGN: Fourteen suction techniques (combinations of device, suction pressure, and suction intermittency) were evaluated sequentially in the trachea of each of 14 in vitro newborn piglets (1 to 4 days old); the order was randomized using a Latin square design. We chose three devices to compare: a meconium aspirator (Neotech Products Inc, Chatsworth, Calif), a hand pump (Res-Q-Vac, Repromed Systems Inc, New York, NY), and a 10F suction catheter (Superior Healthcare Group Inc, Cumberland, RI). Both the meconium aspirator and the hand pump were used with a 3.0-mm endotracheal tube. INTERVENTION: We instilled 0.8 mL of a homogeneous mixture of human meconium and saline (44 g of meconium per 100 mL of saline) in the trachea before applying each suction technique. The meconium aspirator and the suction catheter were each evaluated at three different vacuum pressures, -40, -80, and -150 mm Hg, using both continuous and interrupted suction. The hand pump was evaluated with one and two activations (one activation generates -100 cm H2O, according to the manufacturer). MEASUREMENTS AND RESULTS: The percentage of instilled meconium recovered was consistently greatest (P less than .001) with the meconium aspirator (mean, 88.9% at -150 mm Hg, 84.9% at -80 mm Hg, and 73.5% at -40 mm Hg), intermediate with the catheter (mean, 81.0% at -150 mm Hg, 73.2% at -80 mm Hg, and 67.5% at -40 mm Hg), and least for the hand pump (mean, 67.9% with one activation and 72.6% with two activations). Recovery was better with continuous suction (P = .02) and increasing pressure (P less than .001). CONCLUSIONS: Among the techniques compared, the meconium aspirator at -150 mm Hg, using continuous suction, performed best in this model. It is unknown, however, to what extent the tracheal mucosa may be affected by this degree of negative pressure.

Animals↗
PubMed1992

Management of a piglet model of the meconium aspiration syndrome with high-frequency or conventional ventilation.

OBJECTIVE: To assess the usefulness of three methods of high-frequency ventilation in the early management of a piglet model of the meconium aspiration syndrome. DESIGN: Randomized, block design. SETTING: Animal research facility. SUBJECTS: Fifty-six mixed-breed newborn piglets aged 1 to 4 days and weighing 1.8 to 2.7 kg. INTERVENTIONS: After instillation of a 2.2-mL/kg solution of 25% meconium, 56 piglets were randomized to receive treatment with (1) a conventional positive-pressure infant ventilator, (2) the Bunnell Life Pulse high-frequency jet ventilator, (3) the Bird model VDR high-frequency flow interruptor, or (4) the Infant Star high-frequency flow interruptor. We adjusted ventilator settings to maintain partial pressures of arterial oxygen (PaO2) of 80 to 120 cm H2O and partial pressures of arterial carbon dioxide (PaCO2) of 30 to 50 cm H2O during the 6 hours of ventilation. MEASUREMENTS AND MAIN RESULTS: We compared pulmonary histologic alterations and four physiologic parameters: (1) mean airway pressure, (2) PaCO2, (3) ratio of PaO2 to partial alveolar oxygen pressure (PAO2), and (4) oxygenation index ([(fraction of inspired oxygen)(mean airway pressure)(100)]/PaO2). The two measures of oxygenation were similar for all four devices except at 4 hours, when the PaO2/PAO2 ratio on positive-pressure ventilation was significantly higher than that on high-frequency jet ventilation (P = .008). The histologic changes on positive-pressure ventilation (atelectasis, inflammation, presence of meconium, and exudative debris) were significantly worse than those on high-frequency jet ventilation or flow interruption (P < .0001). CONCLUSIONS: The finding of less severe pathologic alterations with various types of high-frequency ventilators justifies further investigations into the management of the meconium aspiration syndrome with these devices.

Animals↗
PubMed1992

Limitations in the usefulness of urine latex particle agglutination tests and hematologic measurements in diagnosing neonatal sepsis during the first week of life.

We present findings regarding the usefulness of urine latex particle agglutination (LPA) testing for group B streptococcus (GBS) antigen, as well as hematologic values, in diagnosing sepsis during the 1st week of life. Of 475 inborn neonates evaluated, 27 (5.7%) had confirmed sepsis, 47 (9.9%) had indeterminate findings precluding further classification, and 401 (84.4%) were not septic. We examined the following: (1) total white blood cell count (WBC); (2) total polymorphonuclear leukocytes (PMNs); (3) total immature PMNs; (4) immature to total (I:T) neutrophil ratio; (5) immature to mature (I:M) neutrophil ratio; (6) platelet count; (7) a 6-point hematologic score based on the preceding values; and (8) urine LPA for GBS. The positive predictive values of the six hematologic values, as well as the hematologic score, were disappointingly low. Using higher I:T ratios (greater than or equal to 0.30 or 0.40) marginally increased the positive predictive values. More than 60% of our ill, nonseptic neonates had I:T ratios greater than or equal to 0.20. Of 15 infants with culture-proven systemic (blood or cerebrospinal fluid) GBS infection who were tested with urine LPA for GBS antigen, only 4 had positive results. Nineteen infants had positive urine LPAs with concomitant negative blood cultures. Urine cultures were obtained from 18 of these infants. No organisms were isolated from any of these specimens. The mothers of 7 of the infants with positive LPAs and negative blood cultures had received intrapartum antibiotics. Of the remaining 12 infants, the urine LPA was repeated in 8 and results were negative in each case.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Bacterial↗
PubMed1992

Intratracheal suctioning, systemic infection, and the meconium aspiration syndrome.

A retrospective analysis was performed to determine: (1) the proportion of neonates with the meconium aspiration syndrome (MAS) who were not depressed at birth; (2) to evaluate the clinical course of neonates with MAS, particularly relating to whether or not delivery room intubation and intratracheal suctioning had taken place; and (3) to examine the incidence of culture-proven bacteremia among meconium-stained neonates and those with MAS. The medical records of all meconium-stained neonates and those with MAS admitted to our facility from 1985 through 1989 were reviewed. Of 5697 liveborn neonates, 741 (13%) were meconium-stained, of whom 608 (82%) were intubated and suctioned in the delivery room. No complications of the intubation/suctioning procedure were noted in these neonates. Forty-five neonates had culture-proven bacteremia. Five bacteremic neonates had been meconium-stained (0.7% of all such neonates), while 40 were not stained (0.8% incidence). Of 36 neonates with MAS, 1 (2.8%) was bacteremic. Twenty (56%) of 36 newborns with MAS did not require positive pressure ventilation in the delivery room. Twelve (33%) of the babies with MAS had not been intubated and suctioned in the delivery room. Nine (75%) of 12 nonsuctioned neonates, as well as 6 (25%) of 24 suctioned neonates, required mechanical ventilation for more than 6 hours (P = .010). Pneumothoraces occurred in 6 (50%) of 12 nonsuctioned and 5 (21%) of 24 suctioned babies (P = .125). Four of 12 nonsuctioned newborns either died (n = 1) or required extracorporeal membrane oxygenation (n = 3), while only 1 of the suctioned newborns required extracorporeal membrane oxygenation (P = .034).(ABSTRACT TRUNCATED AT 250 WORDS)

Apgar Score↗
PubMed1991

Multiple site blood cultures in the initial evaluation for neonatal sepsis during the first week of life.

We present the first investigation that examines the usefulness of multiple site blood cultures in the initial evaluation for neonatal sepsis during the first week of life. Two sets of blood cultures (1 aerobic and 1 anaerobic bottle/set; BACTEC, NR 6A/7A) from different sites were obtained from 460 inborn infants who were evaluated for possible sepsis. From 0.5 to 1 ml of blood was inoculated into each blood culture bottle. In 18 infants the use of multiple site blood cultures yielded important information. In 8 of these neonates bacteremia was confirmed whereas in 10 cases contamination from skin flora was documented. We could identify no instances in which the delay in antibiotic therapy while the second set of blood cultures was obtained contributed to an adverse outcome. We conclude that multiple site blood cultures are useful in the initial evaluation for suspected sepsis during the first week of life.

Bacterial Infections↗
PubMed1990

Major congenital neurologic malformations. A 17-year survey.

We present characteristics of four major congenital neurologic malformations--anencephaly, spina bifida, encephaloceles, and hydrocephalus--from a population of 763, 364 live-born and still-born infants born from 1971 through 1987. During the 17-year study period, 275 infants had anencephaly (0.36 per 1000 total births), 526 had spina bifida (0.69 per 1000 total births), 112 had encephaloceles (0.15 per 1000 total births), and 370 had hydrocephalus (0.48 per 1000 total births). There was a female preponderance of infants with anencephaly, spina bifida, and encephaloceles, while males predominated among those with hydrocephalus. We found declining incidences of anencephaly, spina bifida, and encephaloceles only among white females. Black infants were significantly less likely than white infants or infants of other races to have spina bifida. Twenty percent of infants with anencephaly had congenital anomalies unrelated to the primary defect, as did 40% with encephaloceles, 37% with hydrocephalus, and 22% with spina bifida. Because the racial background of the patient population closely resembles that of the United States as a whole, the features of the malformations described may reflect those of the country.

Anencephaly↗
PubMed1990

The effect of 100% oxygen on the propagation of tracheobronchial injury during high-frequency and conventional mechanical ventilation.

We compared the histologic alterations in the tracheae and bronchi of 30 premature baboons that were ventilated with either 100% or prn (as needed) oxygen (the fraction of inspired oxygen necessary to maintain the PaO2 between 50 and 80 mm Hg). The baboons were treated with either conventional positive-pressure ventilation (7 were treated with 100%; 7, prn) or high-frequency oscillatory ventilation (8 were treated with 100%; 8, prn). We used a semiquantitative scoring system to grade tissue changes in the trachea, carina, and main-stem bronchi. The fraction of inspired oxygen for all prn animals fell to a plateau of approximately 0.28 after 36 hours, where it remained for the duration of the study. The 15 100% baboons were ventilated for a mean of 139 hours, while the 15 prn baboons were ventilated for a mean of 151 hours. The findings in all conventional and oscillator-ventilated animals were similar and characterized by squamous metaplasia, cilia loss, and goblet cell loss. For both methods of ventilation, there were no differences in the injury scores between 100% and prn oxygen-treated animals. We concluded that there were no additional tracheobronchial histologic changes with 100% oxygen compared with prn oxygen.

Animals↗
PubMed1990

Acrofacial dysostosis with ambiguous genitalia.

We report on a 46,XY infant with mandibulofacial dysostosis, preaxial and postaxial limb anomalies, urethral stenosis with left hydronephrosis, and ambiguous genitalia with phallic/scrotal transposition. This infant with atypical pre/postaxial acrofacial dysostosis (AFD) is the first to be reported with ambiguous genitalia. The acrofacial dysostoses are a heterogenous group of disorders characterized by varying degrees of mandibulofacial dysostosis with acral limb defects and may represent a polytopic field defect. These disorders have generally been separated on the basis of their limb anomalies into preaxial, postaxial, lethal, and atypical types. Most cases are sporadic, but various causes have been postulated including autosomal dominant and recessive inheritance, a chromosome 2q duplication, and a possible case of diabetic embryopathy. We review the nonfacial/limb anomalies in other cases of AFD and compare them to those of our case, thereby expanding the spectrum of anomalies in these disorders.

Abnormalities, Multiple↗
PubMed1990

Management of asymptomatic, term gestation neonates born to mothers treated with intrapartum antibiotics.

Intrapartum antibiotics are frequently administered to parturient women for suspected chorioamnionitis to treat infection in the mother and to prevent or treat infection in the baby. We sent a questionnaire to the 150 United States fellowship program directors in neonatology and pediatric infectious disease, focusing on recommendations for evaluation and therapy of apparently healthy, pretreated, term gestation infants. Eighty-three (55%) of the completed responses were analyzed. Sixteen (19%) respondents do no initial laboratory evaluation but simply observe the baby, 65 (78%) take a complete blood count as well as a platelet count, 59 (71%) obtain blood cultures, 41 (49%) check urine antigen for Group B Streptococcus (GBS) and 23 (28%) perform a lumbar puncture. Only 39% of respondents would begin antibiotic therapy for all pretreated infants. If the evaluation were unremarkable 65 directors would treat for less than or equal to 3 days. If only the urine GBS antigen were positive 47 would treat for greater than or equal to 7 days, while if an elevated immature neutrophil:total neutrophil ratio were the sole abnormality 19 would treat for greater than or equal to 7 days. Forty-four respondents thought that a combination of an elevated immature neutrophil:total neutrophil ratio and a positive urine GBS antigen should always be considered indicative of bacteremia. Given a different scenario, that of a mother treated with intrapartum antibiotics because of a positive cervical culture for GBS and a risk factor (e.g. temperature greater than or equal to 38 degrees C), 58 respondents would begin antibiotics. There is no consensus regarding management of pretreated, healthy appearing, term gestation neonates.

Anti-Bacterial Agents↗
PubMed1990

Different high-frequency ventilator strategies: effect on the propagation of tracheobronchial histopathologic changes.

To assess the role of high-frequency ventilator strategy in the propagation of airway injury, we compared the tracheobronchial histologic alterations in 20 newborn piglets ventilated for 8 hours with high-frequency flow interruption (HFFI). Ten animals were assigned to HFFI with a strategy of continuous pulsations at a frequency of 10 Hz and a mean airway pressure of 16 cm H2O. Ten piglets were treated at identical settings except for 10 one-second baseline pauses per minute to a positive end-expiratory pressure of 5 cm H2O. A semiquantitative scoring system was used to grade light microscopic tissue alterations in the trachea, carina, and mainstem bronchi. Ultrastructural changes were evaluated with scanning electron microscopy. The HFFI-continuous-treated piglets had significantly more damage in all areas than the HFFI-baseline pause group (P less than .001). The upper tracheas of animals in both groups were altered to a greater extent than the lower tracheas (P less than .007). In addition, numerous "skip" areas of injury were noted throughout the tracheas. High-frequency ventilator strategy is a determinant of the severity of airway histologic changes. Factors that adversely affect tissue oxygenation or cause direct mechanical trauma may also influence the degree of injury. Optimal operating characteristics and limitations of different high-frequency devices must be assessed before their use in human neonates.

Animals↗
PubMed1990

Meconium aspiration syndrome: have we made a difference?

Meconium aspiration syndrome (MAS) and its associated complications are reviewed from the period before the routine use of intubation and suctioning to the present (1973 through 1987). Of the 176,790 neonates born during this period, the amniotic fluid was stained in 21,472 (12.15%). Subsequently, MAS developed in 1162 (5.41%) of the meconium-stained neonates. Male neonates were more prone to the disorder than female neonates (P = .022). There were no racial predilections for MAS. The incidence of MAS significantly decreased during the 15 years (P = .043). Of the neonates with MAS, 49 (4.22%) died as a direct consequence of the disorder. The death rate significantly declined during the study period (P = .041). Of the neonates with MAS, 345 (29.7%) required mechanical ventilation, and 134 (11.53%) had pneumothoraxes. Among neonates with MAS, the requirement for mechanical ventilation, as well as the incidence of pneumothoraxes, did not decrease from 1973 through 1987. The incidence of MAS has declined since the advent of combined obstetric and pediatric suctioning of the oropharynx and trachea. Furthermore, there are significantly fewer deaths from the disorder. These declines were likely influenced by other improvements in perinatal care, which have occurred since the early 1970s. The results do not support the contention that severe MAS and resultant deaths can be prevented altogether.

Apgar Score↗
PubMed1990

Circumcision.

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Circumcision, Male↗
PubMed1990

Routine neonatal circumcision: a reappraisal.

Routine neonatal circumcision has long been a controversial subject. The American Academy of Pediatrics has recently outlined a new position on circumcision that is a marked departure from its previous stance. Neonatal circumcision has many potential advantages: The procedure helps prevent urinary tract infections, penile cancer, sexually transmitted diseases and, perhaps, acquired immunodeficiency syndrome. The risk of complications from the procedure is low. Fewer penile problems occur in circumcised boys than in uncircumcised boys. It is more economical to perform the procedure early in life, rather than later. No evidence shows that penile hygiene alone is as beneficial as circumcision.

Circumcision, Male↗