Acute and Critical Care

Original Articles

Effects of Ventilation Modes and Levels of PEEP on Respiratory Mechanics during Controlled Ventilation under General Anesthesia: Jong Cook Park, Sang Hyun Park, Hyun Jun Kwag, Soo Young Park; Korean J Crit Care Med. 2006;21(2):89-94.

Abstract PDF: BACKGROUND
Application of PEEP increases lung volume and improves oxygenation. High PEEP levels may cause alveolar overdistension or barotrauma. It was hypothesized that there will be an effect of level of PEEP on respiratory resistance and an effect of ventilatory mode on respiratory compliance. This study aimed to investigate the effects of ventilation modes and levels of PEEP on respiratory mechanics during controlled ventilation under general anesthesia.
METHODS
In 14 mechanically ventilated patients without cardiopulmonary symptoms and signs, we measured the respiratory mechanics using the inspiration interrupter technique during a constant flow. Dynamic and static compliance, airway resistance, visco-elastic tissue and total respiratory system resistance were calculated at 0, 5, 10, 15, and 20 cmH2O of positive end-expiratory pressure (PEEP) in VCV mode, VCV with inspiratory pause mode, and PCV mode, respectively.
RESULTS
The dynamic compliance of the PCV mode was higher than that of the VCV mode. The highest static compliance was at 10 cmH2O PEEP. At 20 cmH2O PEEP, pulmonary compliance was decreased and the tissue resistance was increased.
CONCLUSIONS
These results suggest that the respiratory mechanics including respiratory resistance should be monitored for applying PEEP. Further studies on clinical condition such as acute lung injury and ARDS were needed.

The Effect of Increased Intra-abdominal Pressure and Positions on Respiratory Mechanics during Laparoscopic Surgery: Jong Cook Park, Hyun Jun Kwak; Korean J Crit Care Med. 2006;21(1):51-56.

Abstract PDF: BACKGROUND
Peritoneal CO2 insufflation results in elevation of PaCO2 and decreased respiratory compliance. Respiratory mechanics can be measured with flow interrupter technique. This study was designed to evaluate the effect of increased intra-abdominal pressure and positions on respiratory mechanics during laparoscopic surgery.
METHODS
Female patients undergoing cholecystectomy (10 degrees head-up group, n=9) and gynecologic operation (10 degrees head-down group, n=9) under laparoscopy were studied. The upper limit of intra-abdonimal pressure was set to 12 mmHg. We measured airway flow and airway pressure of patients at preoperation, during insufflation, during positioning, and postoperation. Respiratory data were obtained from D-lite(R)sensor on-line.
RESULTS
After increased intra-abdominal pressure and positioning, dynamic compliances in both groups were significantly decreased by 31~35%, static compliances by 39~43%. There was no difference of compliance between positions. The elastic tissue resistance of head-up group was significantly elevated compared with after operation. After operation, the respiratory parameters returned nearly to control levels.
CONCLUSIONS
This result suggests that the respiratory mechanics should be monitored under laparoscopy continuously. Further studies on clinical condition such as ascites, hemorrhage, and pregnancy were needed.

Search