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D S Lawson

Publications and source records attributed to D S Lawson.

6 recordsLinked to original sources
PubMed2001

Use of ECMO without the oxygenator to provide ventricular support after Norwood Stage I procedures.

Extracorporeal membrane oxygenation (ECMO) has been found effective in supporting infants with severe cardiac dysfunction following open heart surgery. Centers using this mode of support can also, in instances of single ventricle morphology, consider the option of eliminating the oxygenator from the standard ECMO set-up and thereby provide roller pump ventricular assist. In these cases, the infant's own lungs can provide excellent oxygenation simply by leaving the aortopulmonary shunt open. Since ventricular support ensures maintenance of normal cardiac output, manipulation of pulmonary versus systemic flows is not necessary. This configuration retains the safety features of the ECMO system and is easily staffed by the ECMO support personnel. There may be several benefits to employing this type of management.

Cardiopulmonary Bypass↗
PubMed1999

Staffing issues at open-heart centers offering both pediatric and adult perfusion service: 1998 survey results.

A survey directed to centers offering both pediatric and adult perfusion services was conducted to determine how pediatric cases were distributed among individual perfusionists in their departments. These centers were also asked what they believed the clinical activity level should be for a perfusionist each year to remain proficient in pediatric cardiopulmonary bypass. The questions were asked via e-mail and then followed up with telephone interviews as necessary. Out of the 100 centers contacted, 45 responded to the survey (43 North American, 2 European). Of the forty-five centers, forty-one provided both pediatric and adult perfusion services. Thirty-two centers (78%) offering adult as well as pediatric perfusion services distributed the pediatric caseload to a select group of perfusionists. Nine centers (22%) distributed the pediatric open-heart caseload to the entire staff. From the respondents, the average minimum number of pediatric cases believed necessary to remain proficient in pediatric perfusion was 42.8 cases annually. Centers having dedicated pediatric perfusionists had a slightly higher annual caseload than did those at non-specialized centers, despite practicing at institutions averaging fewer pediatric open-heart cases annually.

Adult↗
PubMed1997

Neural systems mediating American sign language: effects of sensory experience and age of acquisition.

ERPs were recorded from deaf and hearing native signers and from hearing subjects who acquired ASL late or not at all as they viewed ASL signs that formed sentences. The results were compared across these groups and with those from hearing subjects reading English sentences. The results suggest that there are constraints on the organization of the neural systems that mediate formal languages and that these are independent of the modality through which language is acquired. These include different specializations of anterior and posterior cortical regions in aspects of grammatical and semantic processing and a bias for the left hemisphere to mediate aspects of mnemonic functions in language. Additionally, the results suggest that the nature and timing of sensory and language experience significantly impact the development of the language systems of the brain. Effects of the early acquisition of ASL include an increased role for the right hemisphere and for parietal cortex and this occurs in both hearing and deaf native signers. An increased role of posterior temporal and occipital areas occurs in deaf native signers only and thus may be attributable to auditory deprivation.

Adult↗
PubMed1995

A clinical evaluation of the Terumo Capiox SX18R hollow fiber oxygenator.

The Terumo Capiox SX18R is a commercially available, low prime, reverse phase, hollow fiber membrane oxygenator. The oxygenator consists of a 1.8 m2 microporous polypropylene hollow fiber bundle, a 2200 cm2 tubular stainless steel heat exchanger, and an open hard shell venous reservoir with integral cardiotomy filter. The Terumo Capiox SX18R oxygenator was evaluated to determine its clinical oxygenating performance. Blood samples were drawn from 25 patients yielding 114 data points. The following parameters were recorded: blood flow, cardiac index, gas flow, gas to blood flow ratio, and oxygen fraction. Samples were assayed for hematocrit, hemoglobin, arterial and venous blood gas values, and venous oxygen saturation. The data and assay results were used to calculate arterial, venous, and membrane gas oxygen content, oxygen transfer, shunt fraction, and oxygen diffusion capacity. The Terumo Capiox SX18R oxygenator performed adequately with sufficient oxygen transfer reserve and carbon dioxide clearance under a variety of clinical conditions for the tested population.

Adult↗
PubMedDate not supplied

Fractionating language: different neural subsystems with different sensitive periods.

Theoretical considerations and psycholinguistic studies have alternatively provided criticism and support for the proposal that semantic and grammatical functions are distinct subprocesses within the language domain. Neurobiological evidence concerning this hypothesis was sought by (1) comparing, in normal adults, event-related brain potentials (ERPs) elicited by words that provide primarily semantic information (open class) and grammatical information (closed class) and (2) comparing the effects of the altered early language experience of congenitally deaf subjects on ERPs to open and closed class words. In normal-hearing adults, the different word types elicited qualitatively different ERPs that were compatible with the hypothesized different roles of the word classes in language processing. In addition, whereas ERP indices of semantic processing were virtually identical in deaf and hearing subjects, those linked to grammatical processes were markedly different in deaf and hearing subjects. The results suggest that nonidentical neural systems with different developmental vulnerabilities mediate these different aspects of language. More generally, these results provide neurobiological support for the distinction between semantic and grammatical functions.

Adolescent↗