Acute and Critical Care

Letter to the Editor

Neurosurgery
Endovascular Stenting for the Treatment of an Initially Asymptomatic Patient with Traumatic Carotid Artery Dissection: So Hui Yun, Jong Cook Park; Korean J Crit Care Med. 2017;32(3):297-301. Published online August 31, 2017; DOI: https://doi.org/10.4266/kjccm.2017.00010

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Original Articles

Pulmonary
Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model: So Hui Yun, Ho-Jin Lee, Yong-Hun Lee, Jong Cook Park; Korean J Crit Care Med. 2017;32(2):174-181. Published online April 14, 2017; DOI: https://doi.org/10.4266/kjccm.2016.00738

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2 Web of Science
2 Crossref

Background
Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance.
Methods
Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 mL/cmH₂O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 mL/cmH₂O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments.
Results
The mean ± standard deviation ratio of volumes distributed to each lung (V_L1/V_L2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH₂O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, 0.95 cmH₂O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, 1.41 cmH₂O) in the C120 group, compared to ID 8 mm (p < 0.05).
Conclusions
In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Citations

Citations to this article as recorded by

Proof-of-concept study of compartmentalized lung ventilation using system for asymmetric flow regulation (SAFR)
Igor Barjaktarevic, Glen Meyerowitz, Onike Williams, I. Obi Emeruwa, Nir Hoftman
Frontiers in Medical Technology.2023;[Epub] CrossRef
Is It Essential to Consider Respiratory Dynamics?
Youngjoon Kang
The Korean Journal of Critical Care Medicine.2017; 32(2): 223. CrossRef

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.

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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.

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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.

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