A randomised controlled trial on roles of prostaglandin E1 nebulization among patients undergoing one lung ventilation

Background

Prostaglandin E1 (PGE1) has been reported to maintain adequate oxygenation among patients under 60% FiO₂ one-lung ventilation (OLV). This research aimed to explore whether PGE1 is safe in pulmonary shunt and oxygenation under 40% FiO₂ OLV and provide a reference concentration of PGE1.

Methods

Totally 90 esophageal cancer patients treated with thoracotomy were enrolled in this study, randomly divided into three groups (n = 30/group): Group A (60% FiO₂ and 0.1 µg/kg PGE1), Group B (40% FiO₂ and 0.1 µg/kg PGE1), and Group C (40% FiO₂, 0.2 µg/kg PGE1). Primary outcomes were oxygenation and pulmonary shunt during OLV. Secondary outcomes included oxidative stress after OLV.

Results

During OLV, patients in Group C and B had lower levels of PaO₂, SaO₂, SpO₂, MAP, and Qs/Qt than those in Group A (P < 0.05). At T2 (OLV 10 min), patients in Group C and B exhibited a lower level of PaO₂/FiO₂ than those in Group A, without any statistical difference at other time points. The IL-6 levels of patients in different groups were different at T8 (F = 3.431, P = 0.038), with IL-6 in Group C being lower than that in Group B and A. MDA levels among the three groups differed at T5 (F = 4.692, P = 0.012) and T7 (F = 5.906, P = 0.004), with the MDA level of Group C being lower than that of Group B and A at T5, and the MDA level of Group C and B being lower than that of Group A at T7. In terms of TNF-α level, patients in Group C had a lower level than those in Group B and A at T8 (F = 3.598, P = 0.033). Compared with patients who did not use PGE1, patients in Group C had comparable complications and lung infection scores.

Conclusion

The concentration of FiO₂ could be reduced from 60 to 40% to maintain oxygenation. 40% FiO₂ + 0.2 µg/kg PGE1 is recommended as a better combination on account of its effects on the inflammatory factors.

Trial registration: Chictr.org.cn identifier: ChiCTR1800018288, 09/09/2018.

The impact of invasive respiratory support on the development of postoperative atrial fibrillation following cardiac surgery

STUDY OBJECTIVE

Postoperative atrial fibrillation (POAF) is a frequent complication after cardiac valve- or coronary artery bypass (CABG) surgery and is associated with increased mortality. While it is known that prolonged postoperative invasive ventilation triggers POAF, the impact of ventilatory settings on POAF development has not been studied yet.

DESIGN

Prospective observational study.

SETTING

Postoperative Intensive Care Unit.

PATIENTS

Patients having undergone elective CABG and/or cardiac valve surgery.

MEASUREMENTS

Screening for the development of POAF. Patients' clinical data and postoperative ventilatory settings (driving pressure, controlled pressure above positive endexpiratory pressure (PEEP), respiration rate, and FiO2) were investigated to elucidate their impact on POAF.

MAIN RESULTS

Out of 441 enrolled individuals, a total of 192 participants developed POAF (43.5%). We observed that POAF patients received a higher peak driving pressure, and a higher peak respiration rate than non-POAF individuals. Within the multivariate regression model, plateau pressure (adjusted OR 1.199 [1.038-1.661], p = 0.019), driving pressure (adjusted OR 1.244 [1.103-1.713], p = 0.021), and peak respiration rate (adjusted OR 1.206 [1.005-1.601], p = 0.040) proved to be independently associated with the development of POAF. CART analysis revealed a cut-off of ≥17.5 cmH₂O of plateau pressure, ≥11.5 cmH₂O of driving pressure and ≥ 17 respirations per minute as high-risk for POAF development.

CONCLUSIONS

The ventilatory settings of plateau pressure, driving pressure, and respiration rate after cardiac surgery influence POAF occurrence probability. Optimized postoperative care such as lung-protective ventilation and increased awareness towards postoperative ventilatory efforts should be considered to prevent POAF development and poor patient outcome.

Effects of prostaglandin E1 nebulization of ventilated lung under 60%O2 one lung ventilation on patients' oxygenation and oxidative stress: a randomised controlled trial

Background

High FiO₂ during one-lung ventilation (OLV) can improve oxygenation, but increase the risk of atelectasis and oxidative stress. The aim of this study was to analyze whether Prostaglandin E₁ (PGE₁) can improve oxygenation and attenuate oxidative stress during OLV under a lower FiO₂.

Method

Ninety patients selectively undergoing thoracotomy for esophageal cancer were randomly divided into three groups (n = 30/group): Group P (FiO₂ = 0.6, inhaling PGE₁ 0.1 μg/kg), Group L (FiO₂ = 0.6) and Group C (FiO₂ = 1.0). The primary outcomes were oxygenation and pulmonary shunt during OLV. Secondary outcomes included haemodynamics, respiratory mechanics and oxidative stress in serum.

Results

Patients in Group P had significantly higher PaO₂ and lower shunt fraction in 30 min of OLV compared with Group L. Compared with Group C, patients in Group P had similar levels of PaO₂/FiO₂ in 60 min and higher levels of PaO₂/FiO₂ at 2 h during OLV. The levels of PvO₂ and SvO₂ in Group P and Group L were significantly lower than Group C. Patients in Group P and Group L had significantly higher levels of superoxide dismutase and lower levels of malondialdehyde than Group C. No significant differences were found in SPO₂, ETCO₂, PaCO₂, Paw, HR and MAP among the three groups. The complications in Group C were significantly higher than another two groups.

Conclusion

PGE₁ can maintain adequate oxygenation in patients with low FiO₂ (0.6) during OLV. Reducing FiO₂ to 0.6 during OLV can decrease the levels of oxidative stress and complications after OLV.

Trial registration

chictr.org.cn identifier: ChiCTR1800017100.

Short-term one-lung ventilation does not influence local inflammatory cytokine response after lung resection

Background

One-lung ventilation (OLV) is a ventilation procedure used for pulmonary resection which may results in lung injury. The aim of this study was to evaluate the local inflammatory cytokine response from the dependent lung after OLV and its correlation to VT. The secondary aim was to evaluate the clinical outcome of each patient.

Methods

Twenty-eight consecutive patients were enrolled. Ventilation was delivered in volume-controlled mode with a VT based on predicted body weight (PBW). 5 cmH₂O positive end-expiratory pressure (PEEP) and FiO₂ 0.5 were applied. Bronchoalveolar lavage (BAL) was performed in the dependent lung before and after OLV. The levels of pro-inflammatory interleukins (IL-1α, IL-1β, IL-6, IL-8), tumor necrosis factor alpha (TNFα), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF), monocyte chemoattractant protein-1 (MCP-1) and anti-inflammatory cytokines, such as interleukins (IL-2, IL-4, IL-10) and interferon (IFN-γ), were evaluated. Subgroup analysis: to analyze the VT setting during OLV, all patients were ventilated within a range of 5-10 mL/kg. Thirteen patients, classified as a conventional ventilation (CV) subgroup, received 8-10 mL/kg, while 15 patients, classified as a protective ventilation (PV) subgroup, received 5-7 mL/kg.

Results

Cytokine BAL levels after surgery showed no significant increase after OLV, and no significant differences were recorded between the two subgroups. The mean duration of OLV was 64.44±21.68 minutes. No postoperative respiratory complications were recorded. The mean length of stay was for 4.00±1.41 days in the PV subgroup and 4.45±2.07 days in the CV group; no statistically significant differences were recorded between the two subgroups (P=0.511).

Conclusions

Localized inflammatory cytokine response after OLV was not influenced by the use of different VT. Potentially, the application of PEEP in both ventilation strategies and the short duration of OLV could prevent postoperative complications.

Flurbiprofen axetil increases arterial oxygen partial pressure by decreasing intrapulmonary shunt in patients undergoing one-lung ventilation

PURPOSES

In the present study, we investigated whether flurbiprofen axetil (FA) alleviates hypoxemia during one-lung ventilation (OLV) by reducing the pulmonary shunt/total perfusion (Q s/Q t) ratio, and examined the relationship between the Q s/Q t ratio and the thromboxane B2 (TXB2)/6-keto-prostaglandin F1α (6-K-PGF1α) ratio.

METHODS

Sixty patients undergoing esophageal resection for carcinoma were randomly assigned to groups F and C (n = 30 for each group). FA and placebo were administered i.v. 15 min before skin incision in groups F and C, respectively. The partial pressure of arterial oxygen (PaO2) was measured and the Q s/Q t ratio was calculated. Serum TXB2, 6-K-PGF1α, and endothelin (ET) were measured by radioimmunoassay. The relationship between TXB2/6-K-PGF1α and Q s/Q t was investigated.

RESULTS

Compared with group C, PaO2 was higher and the Q s/Q t ratio was lower during OLV in group F (P < 0.05). After treatment with FA, both serum TXB2 and 6-K-PGF1α decreased significantly (P < 0.05) but the TXB2/6-K-PGF1α ratio increased significantly (P < 0.01). Increases in the TXB2/6-K-PGF1α ratio were correlated with reductions in the Q s/Q t ratio during OLV in group F (r = -0.766, P < 0.01). There was no significant difference in serum ET between groups F and C.

CONCLUSIONS

Treatment with FA reduced the Q s/Q t ratio and further increased the PaO2 level during OLV, possibly due to upregulation of the vasoactive agent TXB2/6-K-PGF1α ratio.

Is small tidal volume with low positive end expiratory pressure during one-lung ventilation an effective ventilation method for endoscopic thoracic surgery?

Background

The present study will focus on the rationale for the use of small tidal volume with 6 cmH₂O positive end expiratory pressure (PEEP) with the changes of arterial oxygen tension, plateau airway pressure, and static lung compliance during one lung ventilation for endoscopic thoracic surgery.

Methods

Forty-three patients were intubated with a double-lumen endobronchial tube. After positioning the patients in the lateral decubitus, one-lung ventilation was started with 100% oxygen, tidal volume 10 ml/kg without PEEP; arterial oxygen tension, plateau airway pressure, and static compliance were checked as baseline values (T0). Fifteen minutes later, same parameters were measured (T15). The tidal volume had changed to 6 ml/kg with 6 cmH₂O PEEP. Fifteen minutes later, the same parameters were measured (T30).

Results

Oxygen tension had decreased at T15 (282.1 ± 83.4 mmHg) compared to T0 (477.2 ± 82.4 mmHg) (P < 0.0001), but was maintained at T30 (270.4 ± 81.9 mmHg). There was no difference in peak inspiratory pressure at T15 or T30 compared to T0, plateau airway pressure was increased at T15 and T30 (P < 0.05) and static lung compliance was decreased at T15 and T30 (P < 0.0001).

Conclusions

In carrying out one-lung ventilation for thoracic surgery using an endoscope, the addition of a PEEP of 6 cmH₂O in the dependent lung, while reducing the tidal volume of 6 ml/kg, both oxygen tension and lung compliance are maintained without increasing the plateau airway pressure. Protective lung ventilation is useful for one lung ventilation.

Perioperative tidal volume and intra-operative open lung strategy in healthy lungs: where are we going?

Tidal volumes have tremendously decreased over the last decades from <15 ml kg(-1) to approximately 6 ml kg(-1) actual body weight. Guidelines, widely agreed and used, exist for patients with acute lung injury or acute respiratory distress syndrome (ARDS). However, it is questionable if data created in patients with acute lung injury or ARDS from ventilation on intensive care units can be transferred to healthy patients undergoing surgery. Consensus criteria regarding this topic are still missing because only a few randomised controlled trials have been performed to date, focussing on the use of the best intra-operative tidal volume. The same problem has been observed regarding the application of positive end-expiratory pressure (PEEP) and intra-operative lung recruitment. This article provides an overview of the current literature addressing the size of tidal volume, the use of PEEP and the application of the open-lung concept in patients without acute lung injury or ARDS. Pathophysiological aspects of mechanical ventilation are elucidated.

[Protective ventilation therapy. Also relevant for the operating room?]

General anesthesia and mechanical ventilation affect gas exchange, ventilation and pulmonary perfusion and there is an increasing body of evidence that mechanical ventilation itself promotes lung injury. Lung protective mechanical ventilation in patients suffering from acute lung injury or acute respiratory distress syndrome by means of reduced tidal volumes and limited plateau pressures has been shown to result in reduction of systemic inflammatory mediators, increased ventilator-free days and reduction in mortality. Experimental studies suggest that mechanical ventilation of uninjured lungs may also induce lung damage; however, the clinical relevance remains unknown. Human prospective studies comparing mechanical ventilation strategies during general anesthesia have shown inconsistent results with respect to inflammatory mediators. There is a lack of clinical evidence that lung protective ventilation strategies as used in patients with lung injury may improve clinical outcome of patients with uninjured lungs. The question of which ventilatory strategy will best protect normal human lungs remains unanswered.

Update on one-lung ventilation: the use of continuous positive airway pressure ventilation and positive end-expiratory pressure ventilation--clinical application

PURPOSE OF REVIEW

The purpose of this review is to examine the evidence for and the clinical use of continuous positive airway pressure (CPAP) and positive end-expiratory pressure (PEEP) for the management of one-lung ventilation during thoracic surgery. CPAP and PEEP use are important as we are increasingly challenged with patients with less respiratory reserve and greater comorbidity leading to the need for greater clinical management and more interventions during one-lung ventilation for thoracic surgery to prevent perioperative complications.

RECENT FINDINGS

The focus of this article is on the most recent literature with selected classic articles. First, the supportive literature and rationale for application of PEEP, CPAP or both during thoracic surgery are reviewed, relative to the threats of hypoxemia, hyperoxia and mechanical lung injury. The second part of the article focuses on the clinical use of PEEP and CPAP. Algorithms for the application of CPAP and PEEP to patients both at risk and not at risk of acute lung injury are presented.

SUMMARY

CPAP and PEEP are useful not only to treat hypoxia and atelectasis as the consequence of one-lung ventilation, perhaps more importantly, also as part of a protective lung-ventilation strategy to ameliorate mechanical stress and prevent acute lung injury.