Effects of small tidal volume and positive end-expiratory pressure on oxygenation in pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation / 영남의대학술지

BACKGROUND: The purpose of this study was to investigate whether tidal volume (TV) of 8 mL/kg without positive end-expiratory pressure (PEEP) and TV of 6 mL/kg with or without PEEP in pressure-controlled ventilation-volume guaranteed (PCV-VG) mode can maintain arterial oxygenation and decrease inspiratory airway pressure effectively during one-lung ventilation (OLV).METHODS: The study enrolled 27 patients undergoing thoracic surgery. All patients were ventilated with PCV-VG mode. During OLV, patients were initially ventilated with TV 8 mL/kg (group TV8) without PEEP. Ventilation was subsequently changed to TV 6 mL/kg with PEEP (5 cmH₂O; group TV6+PEEP) or without (group TV6) in random sequence. Peak inspiratory pressure (P(peak)), mean airway pressure (P(mean)), and arterial blood gas analysis were measured 30 min after changing ventilator settings. Ventilation was then changed once more to add or eliminate PEEP (5 cmH₂O), while maintaining TV 6 mL/kg. Thirty min after changing ventilator settings, the same parameters were measured once more.RESULTS: The P(peak) was significantly lower in group TV6 (19.3±.3 cmH₂O) than in group TV8 (21.8±3.1 cmH₂O) and group TV6+PEEP (20.1±3.4 cmH₂O). PaO₂ was significantly higher in group TV8 (242.5±111.4 mmHg) than in group TV6 (202.1±101.3 mmHg) (p=0.044). There was no significant difference in PaO₂ between group TV8 and group TV6+PEEP (226.8±121.1 mmHg). However, three patients in group TV6 were dropped from the study because PaO₂ was lower than 80 mmHg after ventilation.CONCLUSION: It is postulated that TV 8 mL/kg without PEEP or TV 6 mL/kg with 5 cmH₂O PEEP in PCV-VG mode during OLV can safely maintain adequate oxygenation.

Volume-controlled versus pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation / 대한마취과학회지

BACKGROUND: The purpose of this study was to investigate the changes in airway pressure and arterial oxygenation between ventilation modes during one-lung ventilation (OLV) in patients undergoing thoracic surgery. METHODS: We enrolled 27 patients for thoracic surgery with OLV in the lateral decubitus position. The subjects received various modes of ventilation in random sequences during surgery, including volume-controlled ventilation (VCV) and pressure-controlled ventilation-volume guaranteed (PCV-VG) with a tidal volume (TV) of 8 ml/kg of actual body weight. Target-controlled infusion (TCI) with propofol and remifentanil was used for anesthesia induction and maintenance. After double-lumen endobronchial tube (DLT) insertion, the proper positioning of the DLT was assessed using a fiberoptic bronchoscope. Peak inspiratory pressure (Ppeak), exhaled TV, and arterial blood gas were measured 30 min after each ventilation mode. RESULTS: P(peak) was significantly reduced with the PCV-VG mode (19.6 +/- 2.5 cmH2O) compared with the VCV mode (23.2 +/- 3.1 cmH2O) (P < 0.000). However, no difference in arterial oxygen tension was noted between the groups (PCV-VG, 375.8 +/- 145.1 mmHg; VCV, 328.1 +/- 123.7 mmHg) (P = 0.063). The exhaled TV was also significantly increased in PCV-VG compared with VCV (451.4 +/- 85.4 vs. 443.9 +/- 85.9 ml; P = 0.035). CONCLUSIONS: During OLV in patients with normal lung function, although PCV-VG did not provide significantly improved arterial oxygen tension compared with VCV, PCV-VG provided significantly attenuated airway pressure despite significantly increased exhaled TV compared with VCV.

Volume-controlled versus pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation / 대한마취과학회지

BACKGROUND: The purpose of this study was to investigate the changes in airway pressure and arterial oxygenation between ventilation modes during one-lung ventilation (OLV) in patients undergoing thoracic surgery. METHODS: We enrolled 27 patients for thoracic surgery with OLV in the lateral decubitus position. The subjects received various modes of ventilation in random sequences during surgery, including volume-controlled ventilation (VCV) and pressure-controlled ventilation-volume guaranteed (PCV-VG) with a tidal volume (TV) of 8 ml/kg of actual body weight. Target-controlled infusion (TCI) with propofol and remifentanil was used for anesthesia induction and maintenance. After double-lumen endobronchial tube (DLT) insertion, the proper positioning of the DLT was assessed using a fiberoptic bronchoscope. Peak inspiratory pressure (Ppeak), exhaled TV, and arterial blood gas were measured 30 min after each ventilation mode. RESULTS: P(peak) was significantly reduced with the PCV-VG mode (19.6 +/- 2.5 cmH2O) compared with the VCV mode (23.2 +/- 3.1 cmH2O) (P < 0.000). However, no difference in arterial oxygen tension was noted between the groups (PCV-VG, 375.8 +/- 145.1 mmHg; VCV, 328.1 +/- 123.7 mmHg) (P = 0.063). The exhaled TV was also significantly increased in PCV-VG compared with VCV (451.4 +/- 85.4 vs. 443.9 +/- 85.9 ml; P = 0.035). CONCLUSIONS: During OLV in patients with normal lung function, although PCV-VG did not provide significantly improved arterial oxygen tension compared with VCV, PCV-VG provided significantly attenuated airway pressure despite significantly increased exhaled TV compared with VCV.

Effects of tidal volume on arterial oxygenation and intrapulmonary shunt during one lung ventilation / 临床麻醉学杂志

Objective To investigate the effects of different tidal volume (V_T) on arterial oxygenation and intrapulmonary shunt(Q_S/Q_T) during one lung ventilation(OLV).Methods Sixty patients scheduled for selective lobectomy under left lateral decubitus position were randomly divided into groups of A,B and C with 20 cases each.After bronchial induction,two lung ventilation(TLV) was performed with V_T 10 ml/kg,frequency(f) 12 breaths per minute(BPM),ratio of inspiration to expiration(I: E) was 1:2 at first.During OLV,I: E was kept steady,V_T 6 ml/kg and f 20 BPM were chosed in group A,V_T8 ml/kg and f 15 BPM in group B,V_T 10ml/kg,f 12 BPM in group C.Blood gas analysis was determined before OLV (T_1) and at 10 min(T_2) ,20 min(T_3) ,and 30 min after OLV (T_4).Q_S/Q_T and lung complience(Cdyn) was calculated.Results OLV Compaired to T_1,PaO_2 and Cdyn were lower (P<0.05) and Q_S,Q_T and peak airway pression were increased (P<0.05).The decrease of PaO_2 was more in groups of A and C than that in group B(P<0.05).Conclusion During OLV,a better PaO_2.may be maintained with the ventilation parameters of V_T8 ml/kg and f 15 BPM with less increase in Q_S/Q_T and higher Cdyn.

Influence of Preoperative One Lung Ventilation in the Lateral Position on Arterial Oxygenation during Subsequent One Lung Ventilation / 대한마취과학회지

BACKGROUND: There are a few reports with conflicting results regarding the potentiation of hypoxic pulmonary vasoconstriction (HPV) by repeated hypoxic challenges. The aim of this study was to determine if preoperative one lung ventilation (OLV) in the lateral position (LP) for a short time decreases the development of arterial hypoxemia and improves the level of arterial oxygenation via the potentiation of HPV in patients undergoing thoracic surgery with OLV. METHODS: Forty patients were randomly divided into two groups according to presence or absence of preoperative OLV. Preoperative OLV in LP was achieved for 10 minutes with 100% O2 in group P (n = 20). Thereafter, the two lungs were again ventilated with 50% O2 until OLV with 100% O2 had been achieved. In group C (n = 20), the two lungs were continuously ventilated with 50% O2 until OLV with 100% O2 was achieved. The arterial blood samples were obtained 15 minutes after the two lung ventilation in the supine position (baseline) during preoperative OLV in LP, before pulmonary vein ligation, as well as before and after pulmonary artery ligation. The development of arterial hypoxemia (peripheral blood oxygen saturation in pulse oximetry < 95%) in patients undergoing thoracic surgery with OLV was also recorded. RESULTS: Arterial hypoxemia during OLV was observed in 2 cases in group C and 3 cases in group P. There was a similar level of arterial oxygen tension during OLV between the two groups. CONCLUSIONS: This study showed that the preoperative OLV in LP for 10 minutes neither potentiated the HPV response during OLV nor decreased the frequency of arterial hypoxemia during OLV.

Changes in Cardiovascular Function and Arterial Oxygenation during One Lung Anesthesia for Thoracoscopic Sympathectomy / 대한마취과학회지

BACKGROUND: Essential hyperhidrosis is caused by an unexplained over activity of the high thoracic sympathetic nervous system. Since the development of video endoscopic surgery, the use of thoracoscopic sympathectomy has gradually increased. However, reports on major anesthetic problems related to bilateral thoracic symathectomy and one lung ventilation (reventilation of a collapsed lung), which are commonly used for this operation are few. The aim of this study was to evaluate changes in cardiovascular function and arterial oxygenation during reventilation of the collapsed lung for bilateral thoracoscopic sympathectomy. METHODS: Twenty one patients with essential hyperhidrosis in ASA physical status class 1, undergoing bilateral thoracoscopic T2-3 sympathectomy in the semi-Fowler's position were selected. Mean arterial blood pressure (MBP) of both radial arteries, skin temperature of both palmar area, and heart rate (HR) were recorded just before and after, 5 min and 10 min after sympathectomy. Simultaneously, arterial oxygen tension was obtained 30 min after left lung ventilation (LLV, baseline) and right lung ventilation (RLV, left lung collapse) and 10, 20, 30, 40, 50 and 60 min after LLV (reventilation of the collapsed left lung) under general anesthesia (isoflurane-100% oxygen). RESULTS: MBPs of bilateral radial arteries were significantly reduced after sympathectomy. However, there were no difference in the percent change of the MBP between both sides. HR was reduced only after right sympathectomy. The skin temperature of ipsilateral thenar area was significantly elevated after sympathectomy. Aterial oxygen tension was markedly reduced after 10 min of reventilation of the collapsed left lung (246.9 +/- 11.3 --< 102.3 +/- 5.7 mmHg) and then slowly returned to the baseline value after 50 min of reventilation. CONCLUSIONS: Thoracic sympathectomy in patients with essential hyperhidrosis causes a marked decrease of HR and MBP of the bilateral radial arteries and an increase of skin temperature of the ipsilateral palmar area. Reventilation of the collapsed lung for bilateral thoracoscopic T2-3 sympathectomy, causes a marked reduction in the arterial oxygen tension.

The Arterial Oxygenation Effects of CPAP to the Nonventilated Lung during One Lung Ventilation / 대한마취과학회지

Among patients scheduled for elective thoracic surgery at the Medical Center of Kyung Hee University, 15 patients undergoing lobectomy or pneumonectomy were selected. Three different ventilatory modes were employed and compared to the two-lung ventilation with 50% oxygen (control). First, patients were ventilated with 50% oxygen and left the unventilated lung to deflate during one lung ventilation (test 1). Second, continuous positive airway pressure (CPAP) of 10 cmH2O was applied to the ventilated lung while patients were under one lung ventilation with 50% oxygen (test 2). Lastly, patients were ventilated with 100% oxygen and unventilated lung was left to deflate during one lung ventilation (test 3). PaO2, A-aDO2 and Qsp/QT of three different ventilatory modes were observed and compared to that of control, and that of test 2 to test 1. The results were as followed: 1) Mean PaO2 in test 1 and test 2 were 98+/-24.0 mmHg and 126+/-34.8 mmHg, respectively and were significantly decresed as compared to the PaO2 of control, 234+/-21.4 mmHg. Comparing the PaO2 of test 1 and test 2, there was statistically significant increase in test 2 (P<0.01). 2) Comparing with A-aDO2 of control (68+/-22.5 mmHg), A-aDO2 in both test 1 and test 2 were significantly increased to 210+/-24.3 mmHg and 184+/-33.4 mmHg, respectively. there was significantly decreased in test 2 as compared to test 1 (P<0.01). 3) Shunt percentages (Qsp/QT) were measured as 8.3+/-2.3% in control, 25.4+/- 6.7% in test 1, 19.8+/-3.2% in test 2. Shunt percentages of test 1 and test 2 were increased significantly as compared to the control. Comparing the shunt percentages of test 1 and test 2, there was decreased in test 2 (P<0.01). Based on the above results, the application of appropriate CPAP to the unventilated lung during one lung ventilation is thought to be very effective in preventing hypoxemia. But, vigorous and meticulous monitoring, surveilance of patients and one lung ventilation with 100% oxygen are essential depending on the conditions of ventilated lung and long duration of one lung ventilation.