Read through Jon West's Respiratory Physiology. I think it's available on Google Reader, but the paperback is relatively inexpensive. It's an easy read that will help your understanding of ventilation.
This is the book to read prior to any ICU experience. Strong review of basic physiology (a must on the ICU) coupled with practical applciations make this book the best out there. While not pediatric specific most of the chapters (review of respiratory physiology, pressors, ventilatory modes) are pertinent in the PICU.