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Ventilatory consequences of the lateral position and thoracotomy in children
Insights
Mechanically ventilated children undergoing surgery showed increased functional residual capacity (FRC) when placed in the lateral position. Thoracotomy significantly altered FRC, respiratory system compliance (Crs), and arterial oxygen tension (PaO2).
Area of Science:
- Pediatric Anesthesiology
- Respiratory Physiology
- Thoracic Surgery
Background:
- Mechanical ventilation is common in pediatric surgery.
- Understanding respiratory mechanics during anesthesia is crucial for patient safety.
- Changes in patient positioning and surgical procedures can impact lung function.
Purpose of the Study:
- To investigate the effects of lateral positioning and thoracotomy on respiratory parameters in children.
- To measure functional residual capacity (FRC), respiratory system compliance (Crs), and arterial oxygen tension (PaO2) during anesthesia.
- To assess the impact of surgical intervention on these physiological measures.
Main Methods:
- Measurements of FRC, Crs, and PaO2 in ten pediatric patients (2 months to 9 years) during anesthesia.
- Patients underwent surgery for patent ductus arteriosus or coarctation of the aorta.
- Mechanical ventilation with halothane, nitrous oxide, and oxygen was used, with constant FIO2.
Main Results:
- FRC increased by 24% when patients were turned to the lateral position (p=0.0005).
- FRC decreased significantly (p=0.0003) upon pleural opening.
- Lung retraction during surgery caused significant decreases in FRC, Crs, and PaO2.
- Post-surgery, Crs decreased significantly (p=0.0069) compared to pre-operative values.
Conclusions:
- Lateral positioning increases FRC in mechanically ventilated children.
- Thoracotomy leads to significant alterations in FRC, Crs, and PaO2.
- Monitoring respiratory parameters is essential during pediatric thoracic surgery.
Abstract:
Functional residual capacity (FRC), breath-by-breath compliance of the respiratory system (Crs) and arterial oxygen tension (PaO2) were measured in ten children, two months to nine years of age, during anaesthesia for surgical correction of patent ductus arteriosus or coarctation of the aorta. The children were mechanically ventilated with halothane, nitrous oxide and oxygen. FIO2 was kept constant in each child. After induction of anaesthesia, FRC was 17 +/- 7 ml X kg-1 (mean +/- 1 SD), corresponding to 60 +/- 22 per cent of a predicted awake value. FRC increased to 21 +/- 8 ml X kg-1 (p = 0.0005) when the child was turned to its right side and decreased to 13 +/- 5 ml X kg-1 (p = 0.0003) when the pleura was opened. No significant change in Crs or PaO2 occurred during these manoeuvres. Retraction of the upper lung to visualize the great vessels caused a significant decrease in FRC, Crs, and PaO2. The lowest PaO2 observed during this stage was 70.0 mmHg. After surgery FRC and PaO2 were about the same as before surgery while Crs had decreased from 0.87 +/- 0.18 preoperatively to 0.64 +/- 0.15 ml X cmH2O-1 X kg-1 (p = 0.0069). This study shows that FRC increases when mechanically ventilated children are placed in the lateral position, and that thoracotomy is associated with marked changes in FRC, Crs and PaO2.