The Effect of Pneumoperitoneum and Trendelenburg position on respiratory mechanics under general anesthesia during gynecological laparoscopic surgery / Монголын Анагаах Ухаан

Background@#Gynecological laparoscopic surgery requires pneumoperitoneum(PP) with CO₂ gas insufflation and Trendelenburg position. Pneumoperitoneum and Trendelenburg position may impact intraoperative respiratory mechanics in anesthetic management.The goal of this study was to evaluate the influence of Pneumoperitoneum and Trendelenburg position on respiratory mechanics and ventilation. @*Methods@#Twenty one patients scheduled for elective gynecological laparoscopy were evaluated. The patients had no preexisting lung and heart disease or pathologic lung function. Conventional general anesthesia with thiopental sodium, fentanyl, аtracrium and isoflurane was administered. The peak inspiratory pressure, plateau pressure, and end-tidal CO₂ were compared before after creation of pneumoperitoneum with an intraabdominal pressure of 15 mmH₂O, then after PP10, PP20, PP30 minutes in the 20° Trendelenburg position, and after deflation of pneumoperitoneum. The dynamic lung compliance was calculated.@*Results@#During of pneumoperitoneum, there were a significant increase in peak inspiratory pressure by 6 cmH₂O, plateau pressure by 5 cmH₂O, while dynamic lung compliance decreased by 11 ml/cmH₂O. General, the Trendelenburg position induced no significant hemodynamic and pulmonary changes.@*Conclusion@#The effects of pneumoperitoneum significantly reduced dynamic lung compliance and increased peak inspiratory and plateau pressures. The Tredelenburg position did not change these parameters. The end-tidal CO₂ significantly increased after pneumoperitoneum and CO₂ deflation.

The effect on respiratory mechanics when using a Jackson surgical table in the prone position during spinal surgery / 대한마취과학회지

BACKGROUND: Respiratory dynamics may be monitored and evaluated indirectly by measuring the peak inspiratory pressure and plateau pressure. In this study, the respiratory dynamics of patients undergoing spinal surgery using a Jackson surgical table were observed with a device after converting their position from supine to prone. The effects of the dynamic compliance and airway resistance were observed from the changes in peak inspiratory pressure and plateau. METHODS: Twenty five patients were selected as subjects scheduled to undergo lumbar spine surgery. After intubation, the patients were ventilated mechanically with a tidal volume of 10 ml/kg and a respiration rate of 10/min. Anesthesia was maintained with sevoflurane 1.5%, nitrous oxide 2 L/min and oxygen 2 L/min. The peak inspiratory pressure, plateau pressure, resistance, compliance, arterial oxygen tension, carbon dioxide tension, heart rate and arterial blood pressure were measured at 10 minutes after the induction of anesthesia. These parameters were measured again 10 minutes after placing the patient in the prone position. RESULTS: The prone position did not significantly affect the arterial oxygen tension, carbon dioxide tension, blood pressure and heart rate, but significantly increased the peak inspiratory pressure and resistance and decreased the dynamic compliance. CONCLUSIONS: The peak inspiratory pressure was increased using a Jackson surgical table to minimize the abdominal pressure when converting from the supine to prone position. This might be due to a decrease in lung and chest compliance as well as an increase in airway resistance.

The Effects of Tidal Volume on Minimal Occlusion Pressure of Endotracheal Tube Cuff in Patients with Same Peak Inspiratory pressure / 결핵및호흡기질환

BACKGROUND: An excessive endotracheal cuff pressure can cause tracheal injury, and insufficient cuff pressure may not generate an effective cuff seal. The peak inspiratory pressure influences the minimal occlusion pressure of the endotracheal tube cuff. However, the relationship between the minimal occlusion pressure and the tidal volume has not been investigated. This study was conducted to estimate the relationship between the tidal volume and the minimal occlusion pressure of the cuff. METHODS: Ten mechanically ventilated patients were included. The minimal occlusion pressure of the cuff was measured using a pressure gauge. The basal tidal volume was increased and decreased as much as 10% whilst maintaining the same peak inspiratory pressure. The, minimal occlusion pressures were then measured in the high and low tidal volume state, respectively. RESULTS: The peak inspiratory pressure was 32.6+/-.72 cmH2O and the minimal occlusion pressure was 19.0+/-2.26 mmHg in the basal ventilator setting. There was a significant relationship between the peak inspiratory pressure and the minimal occlusion pressure(r=0.77, p<0.01). The minimal occlusion pressure of the cuff was increased to 20.3+/-2.4 mmHg in the high tidal volume state(p<0.05), and decreased to 16.8+/-3.01 mmHg in the low tidal volume state (p<0.001). CONCLUSION: The minimal occlusion pressure of the cuff can be influenced by changes in the tidal volume as well as by the peak inspiratory pressure.

Cumulative Effects of Positive Pressure Ventilation on the Development of Chronic Lung Disease in Very Low Birth Weight Infants

PURPOSE: Barotrauma is one of the most important risk factors of chronic lung disease (CLD) in neonates. However, so-often called `high pressure' does not specify the magnitude or duration of positive pressure ventilation in relation to development of CLD. We investigated whether cumulative effect of positive pressure ventilation over time was more closely associated with CLD than the magnitude of maximal peak inspiratory pressure (PIP) or mean airway pressure (MAP). METHODS: Clinical data were collected from 53 very low birth weight (VLBW) infants (24; CLD and 29; non-CLD) who were treated with mechanical ventilation due to respiratory distress syndrome (RDS) at the neonatal intensive care unit (NICU) in Yonsei University Medical Center. Areas under the pressure-time curve for peak inspiratory pressure (AUCPIP), mean airway pressure (AUCMAP), and FiO2 (AUCFiO2) were calculated from hourly changes of the ventilatory parameters plotted against time during the first 5 days of life, and were compared with the magnitudes of episodic, maximum PIP, MAP or FiO2. RESULTS: The AUCMAP and AUCPIP in CLD group was significantly higher than in non-CLD group (639.8+/-142.9 cmH2O hr vs. 474.2+/-148.0 cmH2O hr, P 0.05). After statistical correction for independent factors related to development of CLD, AUCMAP was shown to be most meaningful. CONCLUSION: Our data are suggestive of the importance of cumulative barotrauma over time in CLD rather than episodic barotrauma caused by cross-sectional or intermittent high peak pressures.

Comparison between Laryngeal Mask Airway and Uncuffed Tracheal Tube for Positive Pressure Ventilation in Paralyzed Pediatric Patients: A Randomized Crossover Study / 대한마취과학회지

BACKGROUND: This randomized cross over study was performed to compare the effect of positive pressure ventilation (PPV) through a laryngeal mask airway (LMA) with that through an uncuffed endotracheal tube (ETT) in paralyzed pediatric patients. Additionally, this study was to determine the protective effect of LMA for the aspiration of oral secretion. METHODS: Pediatric patients (n = 158) weighing less than 30 kg, of ASA physical status 1 or 2 were studied. LMA or ETT was randomly selected and connected to a volume-type ventilator. After measurement and extubation, the other that was not initially used was inserted. Expiratory tidal volume (VT) and airway pressure were measured at the same ventilator setting by a simple pneumo-tachometer, and the expiratory tidal volume ratio (VTR) was calculated as expiratory VT of LMA/expiratory VT of ETT. In randomly selected 39 patients out of 158, methylene blue diluted 1:10 with saline was injected into the oral cavity during PPV through an LMA. At the end of the surgery, fiberoptic bronchoscopy was performed to observe any staining of methylene blue in the trachea. RESULTS: Successful placement of the LMA was achieved in 98% (155/158) of the cases. Expiratory VT through the LMA 1 or 1.5 was decreased if compared with that through the ETT. Leaking pressure of the LMA was lower than that of the ETT except LMA 2.5. VTR of the LMA size 1, 1.5, 2 and 2.5 (mean +/- SD) was respectively 0.94 +/- 0.22, 0.94 +/- 0.14, 1.02 +/- 0.18 and 1.06 +/- 0.19. There was no patient whose trachea was soiled with methylene blue. CONCLUSIONS: Only in older children who are indicated for LMA 2.5, did LMA have the same leakage and the same leaking pressure as ETT during PPV. LMA may not be recommended for the maintenance of PPV in young children less than 10 kg. Inflated LMA seems to have a protective effect against oral secretion.

A Comparison of Pressure Controlled Ventilation and Hybrid Ventilation in Rabbits / 대한마취과학회지

BACKGROUND: Intermittent positive pressure is required to overcome pulmonary airway resistance during inspiration and to deliver an adequate tidal volume. Previous animal experiments have shown that mechanical ventilation may worsen the lung injury when high airway pressure and large tidal volume are required to achieve adequate ventilation and oxygenation. Many ventilatory strategies have been developed to minimize airway pressure increase for the less compliant lung. Intratracheal pulmonary ventilation (ITPV) was developed to allow a decrease in physiological dead space during mechanical ventilation. METHODS: Pressure controlled ventilation (PC) has been compared with hybrid ventilation (HV) which consists of PC and ITPV in 7 rabbits. A reverse thrust catheter (RTC) was introduced into an endotracheal tube (ETT) through an adapter and positioned just above the carina inside the ETT. Fresh gas flowed continuously along the gap between inner cannula and outer cap in the expiratory direction. Gas was intermittently re-directed into the lung as a tidal volume by a valve on the expiratory circuit with ventilatory mode of PC to make HV. Peak inspiratory pressure (PIP) and dead space (VD) at various respiratory rates (RR) of 20/min, 40/min, 80/min and 120/min were compared between PC and HV while maintaining normal PaCO2. RESULTS: The PIPs of PC were 12.4 +/- 3.4 cmH2O, 9.0 +/- 2.7 cmH2O, 8.8 +/- 2.7 cmH2O, and 7.6 +/- 2.5 cmH2O at RR of 20/min, 40/min, 80/min and 120/min, respectively. The PIPs of HV were 9.2 +/- 3.2 cmH2O, 6.2 +/- 1.7 cmH2O, 5.0 +/- 2.0 cmH2O, and 4.5 +/- 1.8 cmH2O at the same RR of 20/min, 40/min, 80/min and 120/min, respectively. The VDS of HV were lower than those of PC. CONCLUSION: It can be concluded that ITPV can be applied as a HV to minimize airway pressure under the setting of PC.

Effect of Positive End-Expiratory Pressure on Intraocular Pressure in the Critically Ill and Mechanically Ventilated Patients / 대한구급학회지

BACKGOUND: The purpose of this study was to examine the effect of various levels of positive end-expiratory pressure (PEEP) on the intraocular pressure in the patients receiving positive pressure ventilation. METHODS: Twenty, critically ill sedated and hemodynamically stable patients without history of glaucoma were placed on controlled positive pressure ventilation. Measured variables included intraocular pressure (IOP), mean arterial pressure (MAP), central venous pressure (CVP), peak inspiratory pressure (PIP) and arterial blood gas analysis (ABGA), and were recorded at zero end-expiratory pressure (ZEEP), and at 5, 10, 15, 20 cmH2O PEEP, applied in random order. RESULTS: IOP increased significantly from 13+/-3 to 16+/-3 mmHg at 15 cmH2O PEEP and from 14+/-4 to 17+/-6 mmHg at 20 cmH2O PEEP. CVP increased significantly from its corresponding ZEEP measurements at all PEEP levels and from 14+/-4 cmH2O at 5 cmH2O PEEP to 21+/-4 cmH2O at 20 cmH2O PEEP. There was a positive correlation between PEEP levels and PIP or CVP but no relationship between PEEP levels and IOP was observed. CONCLUSIONS: The application of PEEP levels > or = 15 cmH2O resulted in a significant increase in the IOP of patients with normal basal ocular tonometry. This study suggests that further increase in IOP may occur in the mechanically ventilated patients with already increased IOP or normal-tension glaucoma, when higher levels of PEEP are used.

The Effect of Intratracheal Pulmonary Ventilation on Dead Space and Airway Pressures in Rabbits with Acute Respiratory Failure Induced by Oleic Acid Injection / 대한마취과학회지

BACKGROUND: Intratracheal pulmonary ventilation (ITPV) was developed to allow a decrease in physiological dead space during mechanical ventilation. To reduce anatomic dead space, a reverse thrust catheter (RTC) is introduced into an endotracheal tube (ETT) through an adapter and positioned just above the carina inside the ETT. ITPV can be combined with pressure control mode of mechanical ventilation to make hybrid ventilation(HV). The effect of HV on the reduction of dead space was compared with that of conventional mechanical ventilation(CMV) in rabbits with acute respiratory failure. METHODS: Oleic acid of 0.06 ml/kg was injected to induce acute respiratory failure in 7 rabbits. PaO2 and PaCO2 were measured 30 minutes after the injection. Oleic acid was injected in another 7 rabbits to compare CMV with HV while increasing the respiratory rate(RR). Tidal volume, dead space(VD) and peak inspiratory pressure(PIP) were measured at the same RR. RESULTS: PaO2 decreased significantly from 467+/- 68 mmHg to 156 +/-26 mmHg at FIO2 1.0 after the injection of oleic acid. In another 7 rabbits, the VD's of CMV were 34+/- 10 ml, 27 +/-10 ml, 20+/- 6 ml, and 18+/- 3 ml at respiratory rate of 20/min, 40/min, 80/min and 120/min, respectively. The VD's of HV were 28 +/-11 ml, 16+/- 8 ml, 9+/- 4 ml, and 7+/- 3 ml at the same respiratory rates as in CMV. The VD's of HV were lower than those of CMV. The PIP's were lower in HV than in CMV. CONCLUSION: We conclude that HV, as the modification of ITPV, can be applied to acute respiratory failure to minimize the airway pressures and dead space of CMV.

Comparison of Cardiorespiratory Effects of Pressure Controlled Ventilation with Volume Controlled Ventilation in Severe Respiratory Failure / 대한마취과학회지

Pressure controlled ventilation has been proposed to recruit closed alveolar units and improve oxygenation through changing the inspiratory flow pattern from a square wave as used with volume controlled ventilation to a rapidly exponentially decaying curve and through maintaining airway pressure at a constant level throughout the inspiratory phase. The purpose of this study was to evaluate the cardiorespiratory efficacy of pressure controlled ventilation in severe respiratory failure. Cardiorespiratory values were measured in ten patients with severe respiratory failure on volume controlled and pressure controlled ventilation. Tidal volume, ventilatory rate, PEEP, inspiratory:expiratory ratio and FIO2 were maintained at the same level for both ventilatory modalities. Changing from volume controlled ventilation to pressure controlled ventilation was associated with significant improvement in PaO2 and decrease in peak inspiratory pressure. There were no significant changes in other cardiorespiratory values, such as arterial blood pressure, heart rate, inspiratory pause pressure and static compliance. These results suggest that pressure controlled ventilation may be a beneficial ventilatory modality in the treatment of severe respiratory failure compared to volume controlled ventilation.

2 cases with adult respiratory distress syndrome in infant and young child

No abstract available.