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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
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↗
PubMed1991

Hemodynamic instability after the initiation of extracorporeal membrane oxygenation: role of ionized calcium.

OBJECTIVES: To prospectively document the occurrence of ionized hypocalcemia in infants and children treated with extracorporeal membrane oxygenation (ECMO), to determine if the type of calcium salt (calcium chloride or gluconate) used in priming the ECMO circuit affected ionized calcium, to determine if ionized calcium concentrations correlate with total calcium, protein, albumin, or total magnesium values, and to determine if the hypotension usually observed after ECMO initiation correlates with low circulating ionized calcium concentrations. DESIGN: Prospective study. SETTING: Pediatric ICU and neonatal ICU. PATIENTS: Sixteen neonatal and three pediatric patients who were started on ECMO for cardiopulmonary support. INTERVENTIONS: The ECMO circuit was primed in a standardized manner, 100 mg of calcium gluconate was added in group 1 patients and 100 mg of calcium chloride was added in group 2 patients. MEASUREMENTS: Ionized calcium was measured from the circuit before initiation of ECMO and from the patient before, and then 5, 10, 15, 30, 60, 120, and 240 mins after initiation of ECMO. Total calcium and ionized calcium concentrations were measured simultaneously every 6 hrs. Serum total protein, albumin, magnesium, and ionized calcium values were measured from blood samples collected simultaneously twice daily. RESULTS: A significant decrease in the mean serum ionized calcium value occurred 5 mins after the initiation of ECMO in both groups, p less than .001. The ionized calcium value remained significantly decreased until 30 mins after the initiation of ECMO. There were no differences between the ionized calcium concentrations obtained during priming with calcium gluconate vs. those concentrations obtained with calcium chloride priming (p = .79). Throughout the course of ECMO, the serum ionized calcium concentrations ranged from 0.60 to 1.86 mmol/L. Poor correlations existed between circulating ionized calcium values and total calcium (r2 = .30), total protein (r2 = .20), albumin (r2 = .20), and magnesium concentrations (r2 = .10). There was a good correlation between the patients' BP and ionized calcium concentrations after bypass was initiated (r2 = .87). CONCLUSION: Our data demonstrate that ionized hypocalcemia is a frequent occurrence after the initiation of ECMO. Since there is a poor correlation between ionized calcium and total calcium, ionized calcium concentrations should be measured directly in these patients.

Blood Pressure↗
PubMed1991

Symptomatic subarachnoid hemorrhage in the term newborn.

A review of the medical records of 35 term newborn infants with confirmed subarachnoid hemorrhage was undertaken to examine etiologic, clinical, laboratory, and neurodevelopmental aspects of this lesion. The most common clinical presentation was convulsive activity (69%), followed by apnea (23%), and bradycardia. Thirty-one of these infants (89%) survived, but only 16 (52%) were felt to be neurologically normal at latest evaluation. Outcomes appeared to be similar regardless of whether the presumed etiology was hypoxic-ischemic or traumatic. Six surviving infants (19%) developed post-hemorrhagic hydrocephalus, but in three of these there was a delayed presentation well beyond the neonatal period. Symptomatic subarachnoid hemorrhage in the term newborn may be a more serious event than previously believed. Close neurodevelopmental follow-up and surveillance for hydrocephalus is warranted.

Brain Diseases↗
PubMed1990

ECMO indications and complications.

Widely adopted while prospective validation was still under way, extracorporeal membrane oxygenation is now a clinically established treatment for reversing neonatal respiratory failure. The technique's accomplishments are impressive-83% survival in conditions otherwise associated with 80% mortality-but its problems include significant handicap in 20% of treated survivors.

Extracorporeal Membrane Oxygenation↗