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Biomedical subjects

S M Donn

Publications and source records attributed to S M Donn.

At least 19 recordsLinked to original sources
PubMed2001

Volume-controlled ventilation. Variations on a theme.

Development of sophisticated transducers and microprocessor-based ventilators now enables the performance of volume-controlled ventilation of newborn infants. Volume-controlled modes include standard intermittent or synchronized intermittent mandatory ventilation; assist-control ventilation; and hybrid modes, such as pressure-support ventilation, pressure-regulated volume-control ventilation, volume-assured pressure support, and volume guarantee. This article describes the concepts and clinical applications of these ventilatory modes.

Humans↗
PubMed2001

Newer modes of mechanical ventilation for the neonate.

For decades, the overwhelming majority of infants requiring mechanical ventilation for respiratory failure were treated with standard time-cycled, pressure-limited intermittent mandatory ventilation. Technologic advances in the 1990s brought forth sophisticated transducers and microprocessor-based mechanical ventilators that enabled implementation of many newer modes of mechanical ventilation. Some of these are volume-targeted rather than pressure-targeted, and many allow an element of patient control of the ventilator, including initiation and termination of inspiration and control of flow. Some modes are even hybrids, combining the best features of both pressure-targeted and volume-targeted modes. This article reviews the principles and salient clinical features of the newer ventilatory modes for newborns with respiratory failure.

Humans↗
PubMed1998

Controversies in patient-triggered ventilation.

Patient-triggered ventilation is a relatively recent development in neonatal mechanical ventilation. Advances in microprocessor-based technology, transducers, and monitoring have enabled patient-driven ventilator control and synchronization of mechanical ventilation with patient effort. The novelty of the newer ventilatory techniques has generated several controversies that remain to be resolved. Among these are signal detection and transduction, the optimal ventilatory modes, and weaning during patient-triggered ventilation.

Electric Impedance↗
PubMed1997

Randomised trial of volume controlled versus time cycled, pressure limited ventilation in preterm infants with respiratory distress syndrome.

Fifty preterm infants weighing 1200 g or more with clinical and radiographic evidence of respiratory distress syndrome, requiring both mechanical ventilation and exogenous surfactant replacement, were randomly allocated to receive either volume controlled ventilation or time cycled, pressure limited ventilation. Tidal volume delivery in each group was deliberately controlled at 5-8 ml/kg so that the only difference between the two groups was the ventilatory modality, the manner in which tidal volume was delivered. The rest of the ventilatory management and clinical care was done according to protocol. The two modes of ventilation were compared by determining the time required to achieve pre-determined success criteria, based on either the alveolar-arterial oxygen gradient or the mean airway pressure as a standard against which the speed of weaning could be objectively assessed. Infants randomised to volume controlled ventilation met success criteria sooner and had a shorter duration of mechanical ventilation. These babies also had a significantly lower incidence of intraventricular haemorrhages and abnormal periventricular echodensities on ultrasound scans. Volume controlled ventilation seems to be both safe and effective in this group of patients.

Air Pressure↗
PubMed1994

Neonatal adrenergic blockade following single dose maternal labetalol administration.

A single 30 mg intravenous dose of labetalol given 20 minutes prior to cesarean delivery at 35 weeks of gestation for severe pregnancy-induced hypertension was associated with symptoms of beta-adrenergic blockade (hypoglycemia, bradycardia, hypotension) in preterm twins. The infants were subsequently found to have therapeutic labetalol concentrations (180 and 150 ng/mL) in umbilical cord blood. The pharmacology of transplacental labetalol is reviewed and potential mechanisms for neonatal beta-adrenergic blockade are discussed.

Adult↗
PubMed1994

Alternatives to ECMO.

The past decade has witnessed technological advancements which are unparalleled in neonatology. ECMO has been demonstrated to be a powerful rescue treatment, but has perhaps been overutilised and is not universally available. Alternative treatments have been shown to be both safe and efficacious in the management of infants with respiratory failure. Direct head to head clinical trials will probably be necessary to establish appropriate criteria and indications for use, given the wide diversity of pathophysiology these unique patients present.

Extracorporeal Membrane Oxygenation↗
PubMed1994

Splenic enlargement in neonates during ECMO.

PURPOSE: To determine whether hepatosplenomegaly was a reproducible finding in seven neonates who were being treated with extracorporeal membrane oxygenation (ECMO) for respiratory failure. MATERIALS AND METHODS: The authors measured splenic and hepatic dimensions with ultrasound (US) at the time ECMO was initiated and then every 24-48 hours until decannulation. Splenic volume and the index of hepatic size were calculated by using published formulas. RESULTS: Splenic volume increased in all seven patients from 8.3 cm3 +/- 1.7 to 16.4 cm3 +/- 4.4 (P < or = .001). Hepatic size did not change markedly. CONCLUSION: Hemolysis, leukopenia, and platelet activation occur during ECMO. Rapid splenic enlargement may be secondary to sequestration of red cells, platelets, and other hematologic elements that have been damaged in the ECMO circuit. Since the liver does not also increase in size, the splenic enlargement is unlikely to be the result of passive congestion.

Extracorporeal Membrane Oxygenation↗
PubMed1991

Multicenter controlled trial comparing high-frequency jet ventilation and conventional mechanical ventilation in newborn infants with pulmonary interstitial emphysema.

One hundred forty-four newborn infants with pulmonary interstitial emphysema were stratified by weight and severity of illness, and randomly assigned to receive treatment with high-frequency jet ventilation (HFJV) or rapid-rate conventional mechanical ventilation (CV) with short inspiratory time. If criteria for treatment failure were met, crossover to the alternate ventilatory mode was permitted. Overall, 45 (61%) of 74 infants met treatment success criteria with HFJV compared with 26 (37%) of 70 treated with CV (p less than 0.01). Eighty-four percent of patients who crossed over from CV to HFJV initially responded to the new treatment, and 45% ultimately met success criteria on HFJV. In contrast, only 9% of those who crossed over from HFJV to CV responded well to CV (p less than 0.01), and the same 9% ultimately met success criteria (p less than 0.05). Therapy with HFJV resulted in improved ventilation at lower peak and mean airway pressures, as well as more rapid radiographic improvement of pulmonary interstitial emphysema, in comparison with rapid-rate CV. Survival by original assignment was identical. When survival resulting from rescue by the alternate therapy in crossover patients was excluded, the survival rate was 64.9% for HFJV, compared with 47.1% for CV (p less than 0.05). The incidence of chronic lung disease, intraventricular hemorrhage, patent ductus arteriosus, airway obstruction, and new air leak was similar in both groups. We conclude that HFJV, as used in this study, is safe and is more effective than rapid-rate CV in the treatment of newborn infants with pulmonary interstitial emphysema.

Bronchopulmonary Dysplasia↗