Biomedical subjects

Warwick W Butt

Publications and source records attributed to Warwick W Butt.

5 recordsLinked to original sources

PubMed2006

Sildenafil prevents rebound pulmonary hypertension after withdrawal of nitric oxide in children.

RATIONALE: Rebound pulmonary hypertension (PHT) can complicate the weaning of nitric oxide (NO), and is in part related to transient depletion of intrinsic cyclic guanosine monophosphate. Rebound is characterized by increased pulmonary arterial (PA) pressure, cardiopulmonary instability, and in some cases, the need to continue NO beyond the intended period of use. There is anecdotal evidence that sildenafil, a phosphodiesterase-5 inhibitor, may prevent recurrence of rebound. OBJECTIVES: We investigated the role of sildenafil in preventing rebound (an increase in PA pressure of 20% or greater, or failure to discontinue NO) in patients in whom previous attempts had not been made to wean from NO. METHODS: Thirty ventilated infants and children, receiving 10 ppm or greater inhaled NO, were randomized to receive 0.4 mg/kg of sildenafil, or placebo, 1 h before discontinuing NO. Twenty-nine patients completed the study. MEASUREMENTS: PA pressures and blood gases were measured before the study drug, and 1 and 4 h after stopping NO. MAIN RESULTS: Rebound occurred in 10 of 14 placebo patients, and 0 of 15 sildenafil patients (p < 0.001). PA pressure increased by 25% (14-67) in placebo patients, and by 1%(-9-5) in sildenafil patients (p < 0.001). Four placebo patients could not be weaned from NO due to severe cardiovascular instability, whereas all sildenafil patients were weaned (p = 0.042). Duration of ventilation after study was 98.0 (47.0-223.5) h for placebo patients and 28.2 (15.7-54.6) h for sildenafil patients (p = 0.024). CONCLUSION: A single dose of sildenafil prevented rebound after withdrawal of NO, and reduced the duration of mechanical ventilation. Prophylaxis with sildenafil should be considered when weaning patients from inhaled NO.

Administration, Inhalation↗

PubMed2006

Early experience with Levosimendan in children with ventricular dysfunction.

OBJECTIVE: To describe our preliminary experience with Levosimendan, a new calcium-sensitizing agent in critically unwell infants and children with severe heart failure. DESIGN: Retrospective cohort analysis. SETTING: Pediatric intensive care unit. PATIENTS: Fifteen children aged 7 days to 18 yrs (median age 38 months) with severe myocardial dysfunction secondary to end-stage heart failure, or acute heart failure, who were inotrope-dependent (requiring at least one catecholamine). INTERVENTIONS: A single dose (bolus and intravenous infusion over 24-48 hrs) of Levosimendan was given under continuous hemodynamic monitoring in our intensive care unit. Eleven children received a single dose, three children received two doses, and one child received four doses. Echocardiographic assessments of ventricular function were made before and 3-5 days after Levosimendan infusion. MEASUREMENTS AND MAIN RESULTS: Heart rate, systolic pressure, diastolic pressure, mean blood pressure, and central venous pressure were unchanged during and after Levosimendan. Levosimendan allowed for discontinuation of catecholamines in ten patients and a dose reduction in three. The dose of dobutamine was reduced from 6.4 microg/kg/min pre-Levosimendan to 1.8 microg/kg/min on day 5 (p < .01). Ejection fraction for the group as a whole improved from 29.8% to 40.5% (p = .015); this did not increase significantly in patients with end-stage heart failure but increased by 63% in the children with acute heart failure. CONCLUSIONS: Levosimendan can be safely administered to infants and children with severe heart failure. Levosimendan allowed for substantial reduction in catecholamine infusions in children with end-stage or acute heart failure and also produced an objective improvement in myocardial performance in children with acute heart failure.

Adolescent↗

PubMed2005

Extending the limits of extracorporeal membrane oxygenation: lung rest for a child with non-specific interstitial pneumonia.

OBJECTIVE: Veno-venous extracorporeal membrane oxygenation (ECMO) is an established therapy for the treatment of respiratory failure. Traditionally ECMO has been used to support patients with an acute, reversible disease process, with a predictable outcome. We report the successful use of veno-venous ECMO for an unusual indication. PATIENT: A 10-year old girl was admitted to intensive care with severe, hypoxic respiratory failure on the background of a 2-month history of worsening respiratory symptoms. She required high levels of conventional positive pressure ventilation, and high frequency oscillation. Lung biopsy confirmed a non-specific interstitial pneumonia, and the patient was commenced on immune suppressive therapy. Her clinical course was further complicated by pulmonary haemorrhage and severe air leak. INTERVENTIONS: On day 20 after admission the patient was placed on veno-venous ECMO for lung rest while awaiting a response to continued medical treatment. She required ECMO for 20 days, during which time sedation was reduced, and she was able to interact with those around her. The patient's ventilatory requirements after decannulation were minimal, and she subsequently made a steady clinical recovery. CONCLUSIONS: ECMO was safely and successfully used to provide a period of lung rest and time for medical therapy to take effect in a child with an unusual indication for support: a rare disease with an uncertain outcome on the background of prolonged mechanical ventilation.

Child↗

PubMed2005

Comparison of indirect methods of measuring intra-abdominal pressure in children.

OBJECTIVE: To determine the most accurate indirect method of measuring intra-abdominal pressure (IAP) in children. DESIGN AND SETTING: Single-centre, prospective, clinical study in a 23-bed specialist paediatric intensive care unit in Australia. PATIENTS AND PARTICIPANTS: 20 children admitted to paediatric intensive care with a peritoneal dialysis catheter in situ following congenital cardiac surgery. INTERVENTIONS: IAP was measured directly via the peritoneal dialysis catheter and by intragastric manometry via an indwelling nasogastric tube, and by intravesical manometry via an indwelling transurethral urinary catheter, using volumes of 0, 1, 3 and 5 ml/kg body weight of sterile saline instilled into the bladder. MEASUREMENTS AND RESULTS: Across the range of IAPs of 1-8 mmHg the Bland-Altman method for assessing agreement between two methods of clinical measurement showed bladder pressure measured via the urinary catheter with 1 ml/kg body weight of saline instilled to be the most accurate indirect measurement technique, tending to give pressures between 0.07 and 1.23 mmHg higher than the direct measurement (95% CI for bias). Measuring bladder pressure with either no saline instilled or more saline per kilogram body weight instilled was less accurate over the same range of pressures, as was measuring the gastric pressure. CONCLUSIONS: The most accurate indirect method of measuring IAP in children over the normal range of IAPs involves measuring bladder pressure via a transurethral urinary catheter with 1 ml/kg body weight of sterile saline instilled into the bladder.

Abdomen↗

PubMed2004

Effect of peritoneal dialysis on intra-abdominal pressure and cardio-respiratory function in infants following cardiac surgery.

OBJECTIVE: To investigate the relationship between dialysate volume, intra-abdominal pressure, and cardio-respiratory function in infants following cardiac surgery. DESIGN: Prospective pilot study. SETTING: Paediatric intensive care unit. PATIENTS: Six infants undergoing peritoneal dialysis within 24 h of cardiopulmonary bypass. INTERVENTIONS: Manipulation of the volume of dialysate at levels of 0, 10, 20, and 30 ml/kg in variable order. MEASUREMENTS AND MAIN RESULTS: Intra-abdominal pressure was measured at each volume of dialysate via a pressure transducer connected to the dialysis catheter. Haemodynamic data was collected, including cardiac output, which was measured by thermodilution via a 3.5-French gauge catheter placed in the pulmonary arterial pathway. Respiratory data included PaO2, PaCO2, and dynamic compliance. Intra-abdominal pressure increased with increasing volume of dialysate (p < 0.001), though there was considerable variation between patients in the magnitude of increase. Intra-abdominal pressure remained low even with 30 ml/kg in the abdomen. In three infants, intra-abdominal pressure was re-measured in the absence of muscle relaxants, and was found to be higher in each case. No negative effects on cardiac output, markers of delivery of oxygen, or respiratory function were seen even at volumes of 30 ml/kg. Cardiac index was significantly higher with 10 ml/kg than when the abdomen was empty or contained a larger volume (p < 0.05). CONCLUSIONS: In this small group of infants, intra-abdominal pressure increased with increasing volumes of dialysate but remained low, even with 30 ml/kg in the abdomen, and was not associated with any deleterious effects on cardio-respiratory performance.

Abdomen↗