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Biomedical subjects

David Bateman

Publications and source records attributed to David Bateman.

8 recordsLinked to original sources
PubMed2005

Variables associated with the early failure of nasal CPAP in very low birth weight infants.

OBJECTIVE: To identify risk factors and neonatal outcomes associated with the early failure of "bubble" nasal continuous positive airway pressure (CPAP) in very low birth weight (VLBW) infants with respiratory distress syndrome (RDS). STUDY DESIGN: Following resuscitation and stabilization at delivery, a cohort of 261 consecutively inborn infants (birth weight < or = 1250 g) was divided into three groups based on the initial respiratory support modality and outcome at 72 hours of age: "ventilator-started" group, "CPAP-failure" group, and "CPAP-success" group. RESULTS: CPAP was successful in 76% of infants < or = 1250 g birth weight and 50% of infants < or = 750 g birth weight. In analyses adjusted for postmenstrual age (PMA) and small for gestational age (SGA), CPAP failure was associated with need for positive pressure ventilation (PPV) at delivery, alveolar-arterial oxygen tension gradient (A-a DO2) >180 mmHg on the first arterial blood gas (ABG), and severe RDS on the initial chest x-ray (adjusted odds ratio [95% CI] = 2.37 [1.02, 5.52], 2.91 [1.30, 6.55] and 6.42 [2.75, 15.0], respectively). The positive predictive value of these variables ranged from 43% to 55%. In analyses adjusted for PMA and severe RDS, rates of mortality and common premature morbidities were higher in the CPAP-failure group than in the CPAP-success group. CONCLUSION: Although several variables available near birth were strongly associated with early CPAP failure, they proved weak predictors of failure. A prospective controlled trial is needed to determine if extremely premature spontaneously breathing infants are better served by initial management with CPAP or mechanical ventilation.

Birth Weight↗
PubMed2004

The role of the temporal lobe semantic system in number knowledge: evidence from late-stage semantic dementia.

Previous reports have demonstrated that many aspects of number knowledge remain unimpaired in semantic dementia, despite severe comprehension problems in other domains. It is argued that this advantage for numbers arises because the disease spares the parietal lobe magnitude system thought to be critical for number processing. Models of numerical cognition that favour a separation between verbal and magnitude representations of number might, however, predict a restricted impairment of the verbal number code in this condition. We obtained support for this hypothesis in a patient with late-stage semantic dementia. She was impaired at a variety of tasks tapping the verbal number code; for example, reading and writing Arabic numerals, naming and word-picture matching with dot pictures, reading aloud number words, digit span and magnitude comparison/serial ordering tasks with number words. In contrast, she demonstrated good understanding of the magnitude and serial order of numbers when tested with Arabic numerals and non-symbolic representations. These findings suggest that although the magnitude meaning of numbers is isolated from the temporal lobe semantic system, the anterior infero-temporal lobe may play a critical role in binding English number words to their non-symbolic magnitude meaning.

Aged↗
PubMed2004

A category-specific advantage for numbers in verbal short-term memory: evidence from semantic dementia.

This study explored possible reasons for the striking difference between digit span and word span in patients with semantic dementia. Immediate serial recall (ISR) of number and non-number words was examined in four patients. For every case, the recall of single-digit numbers was normal whereas the recall of non-number words was impaired relative to controls. This difference extended to multi-digit numbers, and remained even when frequency, imageability, word length, set size and size of semantic category were matched for the numbers and words. The advantage for number words also applied to the patients' reading performance. Previous studies have suggested that semantic memory plays a critical role in verbal short-term memory (STM) and reading: patients with semantic dementia show superior recall and reading of words that are still relatively well known compared to previously known but now semantically degraded words. Additional assessments suggested that this semantic locus was the basis of the patients' category-specific advantage for numbers. Comprehension was considerably better for number than non-number words. Number knowledge may be relatively preserved in semantic dementia because the cortical atrophy underlying the condition typically spares the areas of the parietal lobes thought to be crucial in numerical cognition but involves the inferolateral temporal-lobes known to support general conceptual knowledge.

Aged↗
PubMed2004

Surface dyslexia in semantic dementia: a comparison of the influence of consistency and regularity.

This study addressed the question of exactly which aspects of spelling-sound consistency influence accuracy of reading aloud in surface dyslexic patients with semantic dementia. Oral reading data were obtained from twelve patients on three sets of words that varied in regularity (defined according to grapheme-phoneme correspondences) and consistency (defined according to the pronunciation of word body neighbours). The patients were less accurate for irregular/inconsistent words, which they commonly pronounced in line with sound-spelling regularities, as expected in surface dyslexia. They produced plausible but incorrect responses for some regular as well as many irregular words, suggesting that their reading performance was influenced by sound-spelling relationships not captured by grapheme-phoneme correspondences. On a set of items that varied consistency and regularity independently, the patients showed a large effect of regularity and a smaller but significant effect of consistency in reading aloud. In addition, there was a correlation between degree of semantic impairment and level of reading accuracy for inconsistent items. These findings are discussed in terms of two influential models of reading: the dual-route-cascaded model (Coltheart et al., 2001) and the triangle model (Plaut et al., 1996). It is argued that the triangle model provides a more straightforward account of the relationship between word comprehension and consistency effects in reading.

Aged↗
PubMed2004

When does word meaning affect immediate serial recall in semantic dementia?

Patients with semantic dementia can show superior immediate recall of words that they still understand relatively well, as compared with more semantically degraded words, suggesting that conceptual knowledge makes a major contribution to phonological short-term memory. However, a number of studies have failed to show such a recall difference, challenging this view. We examined the effect of several methodological factors on the recall of known and degraded words in 4 patients with semantic dementia, in order to investigate possible reasons for this discrepancy. In general, our patients did exhibit poorer recall of the degraded words and made more phonological errors on these items. In addition, set size affected the magnitude of the recall advantage for known words. This finding suggests that semantic degradation influenced the rate of learning in the immediate recall task when the same items were presented repeatedly. The methods used to select known and degraded items also impacted on the recall difference. List length, however, did not affect the advantage for known words. The coherence of items in phonological short-term memory was affected by their semantic status, but not by the length of the material to be retained. The implications of these findings for the role of semantic and phonological representations in verbal short-term memory are discussed.

Aged↗
PubMed2002

Inhaled nitric oxide and gentle ventilation in the treatment of pulmonary hypertension of the newborn--a single-center, 5-year experience.

OBJECTIVE: To evaluate the effect of inhaled nitric oxide (INO) in pulmonary hypertension of the newborn (PH) in a single center over 5 years using gentle ventilation (GV), without hyperventilation or induced alkalosis. METHODS: Data from 229 consecutive infants with PH of varied etiology treated with INO and GV, and from 67 infants with meconium aspiration syndrome (MAS) and primary PH (PPHN) treated with GV alone were reviewed over a 5-year period (86% outborn). INO was initiated at 25 ppm when PH and severe hypoxemia persisted despite maximal optimal ventilation. Hyperventilation or systemic alkalosis were not attempted. RESULTS: Mean duration of ventilation was 9.9 +/- 14 days (median 6.5 days). Average mean airway pressure (MAP) dropped from 17.7 +/- 4.3 cm H(2)O at the referral hospital to 13.2 +/- 2.5 cm H(2)O (p < 0.001) following admission to our unit using conventional settings and GV, before starting INO. Mean oxygenation index (OI) dropped from 46.8 +/- 24.5 to 22.7 +/- 21.4 within 24 hours of INO therapy (p < 0.001). Infants with higher baseline pH and lower baseline OI responded better to INO (p < 0.02). Overall survival was 72%. Patients with MAS and PPHN had the best response, 92% survived and there was a 46% reduction in need for extracorporeal membrane oxygenation (ECMO) compared to historical pre-INO period controls (23.9% vs. 12.8%, p < 0.01). In the infants treated with GV alone, the MAP dropped from 17.2 +/- 4.3 cm H2O at the referral hospital to 12.6+/-2.4 after GV was started in our unit. CONCLUSIONS: We conclude that INO is an effective and well-tolerated therapy for PH in infants receiving GV.

Academic Medical Centers↗