Paediatric intensive care in Sweden. : I Mechanical ventilation and central haemodynamics. II Outcome of paediatric intensive care with special reference to respiratory failure

Detta är en avhandling från Stockholm : Karolinska Institutet, Department of Physiology and Pharmacology

Sammanfattning: The ABC of acute care is to maintain Airway, Breathing and Circulation or oxygen delivery, which depends on the product of cardiac output (CO) and oxygenation. Thus knowledge of how different modes of mechanical ventilation affect central haemodynamics is essential. Paper I: Improved triggering function made pressure support ventilation (PSV) possible for neonates and infants. We evaluated the effect on cardiac output of this mode in comparison with conventional pressure control ventilation in infants (n=9). We found a significant improvement in cardiac output by 16% during PSV. This finding may be of importance for critically ill infants. Paper II: In Paper I we did not find any significant change in heart rate, thus the increase in CO was caused by an increase in stroke volume (SV). The ability of the neonatal heart to change stroke volume has been debated. In a study of anaesthetized infants on mechanical ventilation (n=6), the PEEP-level was changed and CO measured. Data on CO, SV and heartrate were analysed together with data from Paper I. There was an almost linear significant change in CO, from +16% to -13% without changes in heart rate. Thus we found that when mean airway pressure is altered the changes in CO is an effect of changes in SV. Paper III: High frequency oscillatory ventilation (HFOV) is a new method of mechanical ventilation with tidal volumes Few studies have been carried out on the incidence and outcome of paediatric intensive care or more specifically on respiratory failure. There are also differences regarding population, mortality and health between different regions. Thus international studies may not apply to Scandinavia. To investigate the circumstances in Sweden the following studies were performed: Paper IV: An ambidirectional multicentre population based collection of data on all admissions to ICU of children aged 6 months (in PICU 1 month) to 16 years of age during 36 months 1998-2001. Only a minority of children needing intensive care in Swedenreceived that in a designated paediatric ICU (PICU). Mortality was similar in PICU and adult ICUs. There is a continued increased mortality for at least five years after admission to an ICU. Studies are needed to evaluate if centralization of paediatric intensive care in Sweden would be beneficial to the paediatric population. Paper V: The subgroup with respiratory failure in PICU, were further studied; 20% of admissions were ventilated >24 hours. NO, HFOV and ECMO was used in 15% of these cases indicating a severe respiratory disease. This group had an initial increased mortality but one year after discharge from ICU the mortality was not increased. Results from one PICU, show that ARDS is relatively uncommon but accounts for close to 1/3 of the total ICU mortality in this PICU. This suggests that ARDS may be a significant health issue in children in Sweden.

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