Outcomes of paediatric patients ventilated in a high-care area outside an intensive care unit.

BACKGROUND: Limited availability of paediatric intensive care beds in the public sector is a major challenge in South Africa. It often results in patients being ventilated in a high-care area (HCA) outside an intensive care setting. The outcomes of paediatric patients ventilated outside a paediatric intensive care unit (ICU) are not well documented. OBJECTIVES: To describe characteristics and outcomes of patients ventilated in a paediatric HCA. METHODS: A retrospective chart review of children (0 - 16 years) requiring mechanical ventilation in the HCA at Chris Hani Baragwanath Academic Hospital, Johannesburg, between 1 February and 31 October 2015 was performed. RESULTS: A total of 214 patients required mechanical ventilation during the study period. Fifty-four percent were male and 91.1% were HIV-negative. The most common diagnoses were acute lower respiratory tract infections (59.3% of the post-neonatal group, 28.8% of the neonatal group) and sepsis (6.8% of the post-neonatal group, 28.8% of the neonatal group). The ultimate rate of acceptance to an ICU was 69.0%. Only 41.6% of cases referred to an ICU were initially accepted, with limited bed availability being the main reason for refusal. Patients with respiratory illnesses were more likely and those with neurological illness less likely to be accepted to an ICU. Patients with low-risk diagnoses were more likely to be accepted than those with very high-risk diagnoses. The overall mortality rate was 32.2%, with 52.2% of these deaths occurring in the HCA. Patients aged 1 - 5 years had the highest mortality rate (48.0%). Lower respiratory tract infections (36.8%) and sepsis (20.6%) were the main causes of death. The mortality rate of suitable ICU candidates in the HCA was higher than that in an ICU (33.3% v. 24.3%). The standardised mortality ratio (SMR), as predicted by the Paediatric Index of Mortality 3 score, for all patients who died in the HCA was 3.3, while the SMR for patients who died in an ICU was 1.3. The odds ratio for mortality of suitable candidates ventilated in the HCA v. patients who were ventilated in an ICU was 1.80 (95% confidence interval 1.39 - 6.03). CONCLUSIONS: Although a reasonable number of paediatric patients ventilated in an HCA survive, survival is lower than in those ventilated in an ICU. However, offering life-supporting therapies in an HCA may offer benefit where ICU care is unavailable. Emphasis needs to be placed on improving access to ICU care as well as optimising the use of available resources.

High-frequency oscillatory ventilation in a tertiary paediatric intensive care unit in an academic hospital in Johannesburg, South Africa.

Background: High-frequency oscillatory ventilation (HFOV) remains an option for the management of critically ill children when conventional mechanical ventilation fails. However, its use is not widespread, and there is wide variability reported with respect to how it is used. Objectives: To describe the frequency, indications, settings and outcomes of HFOV use among paediatric patients with a primary respiratory disorder admitted to a tertiary paediatric intensive care unit (PICU). Methods: The study was a 2-year, single-centre, retrospective chart review. Results: Thirty-four (32.7%) patients were managed with HFOV in the PICU during the study period. Thirty-three of the 34 patients had paediatric acute respiratory distress syndrome. Indications for HFOV were inadequate oxygenation in 17 patients (50%), and refractory respiratory acidosis in 15 patients (44.1%) (2 patients did not fit into either category). Approaches to the setting of HFOV varied considerably, particularly with respect to initial pressure around the airways. HFOV was effective at improving both oxygenation, with a median (interquartile range (IQR)) decrease in oxygenation index of 6.34 (5.0 - 9.5), and ventilation with a the median decrease in PaCO2 of 67.6 (46.2 - 105.7) mmHg after 24 hours. Overall mortality was 29.4% in the HFOV group, which is consistent with other studies. Conclusion: HFOV remains an effective rescue ventilatory strategy, which resulted in rapid and sustained improvement in gas exchange in patients with severe hypoxaemia and/or severe respiratory acidosis, particularly in the absence of extracorporeal support. However, the variability in practice and the adverse effects described highlight the need for future high-quality randomised controlled trials to allow for development of meaningful guidelines to optimise HFOV use. Contributions of the study: This study describes the use and outcomes of high-frequency oscillatory ventilation (HFOV) in a South African paediatric intensive care unit, thus addressing a local knowledge gap and providing evidence of the continued efficacy of HFOV for severe hypoxaemia and refractory respiratory acidosis in settings without access to extracorporeal technologies.

High-frequency oscillatory ventilation in a tertiary paediatric intensive care unit in an academic hospital in Johannesburg, South Africa

Background. High-frequency oscillatory ventilation (HFOV) remains an option for the management of critically ill children when conventional mechanical ventilation fails. However, its use is not widespread, and there is wide variability reported with respect to how it is used. Objectives. To describe the frequency, indications, settings and outcomes of HFOV use among paediatric patients with a primary respiratory disorder admitted to a tertiary paediatric intensive care unit (PICU). Methods. The study was a 2-year, single-centre, retrospective chart review. Results. Thirty-four (32.7%) patients were managed with HFOV in the PICU during the study period. Thirty-three of the 34 patients had paediatric acute respiratory distress syndrome. Indications for HFOV were inadequate oxygenation in 17 patients (50%), and refractory respiratory acidosis in 15 patients (44.1%) (2 patients did not fit into either category). Approaches to the setting of HFOV varied considerably, particularly with respect to initial pressure around the airways. HFOV was effective at improving both oxygenation, with a median (interquartile range (IQR)) decrease in oxygenation index of 6.34 (5.0 - 9.5), and ventilation with a the median decrease in PaCO2 of 67.6 (46.2 - 105.7) mmHg after 24 hours. Overall mortality was 29.4% in the HFOV group, which is consistent with other studies. Conclusion. HFOV remains an effective rescue ventilatory strategy, which resulted in rapid and sustained improvement in gas exchange in patients with severe hypoxaemia and/or severe respiratory acidosis, particularly in the absence of extracorporeal support. However, the variability in practice and the adverse effects described highlight the need for future high-quality randomised controlled trials to allow for development of meaningful guidelines to optimise HFOV use

Calcium transport, Ca2(+)-ATPase, and lipid order in rabbit ocular lens membranes.

Calcium transport was monitored by measuring ATP-dependent 45Ca uptake into membrane vesicles prepared from rabbit lens cortex. Calcium-stimulated adenosinetriphosphatase (Ca2(+)-ATPase) activity was also measured in the same membrane preparation. Both uptake and Ca2(+)-ATPase activity were inhibited by vanadate. Calcium activation of the uptake process was similar to that of the Ca2(+)-ATPase. Calcium uptake was prevented by calcium ionophore A23187, suggesting that the calcium transported into the vesicles remains diffusible. The ATP-dependent calcium uptake probably represents the transport of calcium into "inside-out" membrane vesicles by the Ca2(+)-ATPase mechanism that normally shifts calcium outward from the lens cytoplasm. The temperature dependence of the Ca2(+)-ATPase and the calcium uptake process was determined. Because lipid order can influence Ca2(+)-ATPase function, we attempted to correlate calcium transport with the physical state of the membrane lipids. Infrared spectroscopy was used to determine the temperature dependence of the CH2 symmetric stretching frequency (an order parameter) in the lipids. A similarity was noted between the temperature-dependence curves for lipid order, Ca2(+)-ATPase, and calcium uptake rate. Entropy, enthalpy, and transition temperature calculated for the Ca2(+)-ATPase and calcium uptake process were in the same range as those parameters calculated for the lipid-phase transition.