One-lung Ventilation For Thoracic Surgery Research Articles

Trachway® flexible stylet facilitates the correct placement of double-lumen endobronchial tube: a prospective, randomized study

BackgroundThe mainstream facilitation of one-lung ventilation is using double-lumen endobronchial tubes. However, it is more difficult to be positioned properly and more likely to cause airway injuries. How to place double-lumen endobronchial tubes rapidly and correctly is important for thoracic anesthesiologists.MethodsOne hundred eight patients with an American Society of Anesthesiologists physical status of I to III were 20 years of age or over, and required one-lung ventilation for thoracic surgery. They were randomly assigned to the conventional technique group (n = 36), the flexible fiberoptic bronchoscopy group (n = 36), or the Trachway® flexible stylet group (n = 36). The primary endpoint was the time needed for intubation. T1, the time from the tip of the blade passing between the patient’s lips to identification of the vocal cords; and T2, the time from identification of the vocal cords to the bronchial lumen was in the correct position.ResultsT1 had no significant difference between groups, but T2 was significantly shorter in the Trachway® flexible stylet group (p < 0.0001) and longer in the conventional technique group (p < 0.0001).ConclusionsUsing Trachway® flexible stylet for correct placement of double-lumen endobronchial tubes not only significantly shortened the intubation time, but also reduced incidence of carinal injuries. It is an alternative, and a choice with good safety.Trial registrationClinicalTrials.gov Identifier: NCT02364622, 18/02/2015, Retrospectively registered.

Unilateral Negative-Pressure Pulmonary Edema Following One-Lung Ventilation for Thoracic Surgery.

Unilateral Negative-Pressure Pulmonary Edema Following One-Lung Ventilation for Thoracic Surgery.

Effects of different positive end-expiratory pressure titrating strategies on oxygenation and respiratory mechanics during one- lung ventilation: a randomized controlled trial.

Positive end-expiratory pressure (PEEP) is widely used to reduce the risk of hypoxemia and atelectasis during one-lung ventilation (OLV); however, the optimal strategy for PEEP titrating remains unclear.The purpose of the study was to investigate the effects of different PEEP titrating strategies on oxygenation and respiratory mechanics during OLV. Patients undergoing thoracic surgery with general anesthesia were randomly allocated into five groups. In P0 group, PEEP was set to zero; in PLIP2 group, PEEP was set to 2 cmH2O plus the pressure of lower inflection point (LIP) of pressure-volume (P-V) curve; in PLIPS group, PEEP was titrated to achieve maximum static compliance from the averaged LIP pressure value; in groups PSTAT and PDYN, the incremental PEEP values were titrated to achieve maximum static compliance or maximum dynamic compliance from 4 cmH2O. Hemodynamic measurements, respiratory mechanics, and blood gas analyses were recorded at the beginning of OLV, OLV 15 min, OLV 30 min, OLV 45 min, and OLV 60 min. Also, the intrapulmonary shunt (Qs/Qt), physiological dead space to tidal volume ratio (VD/VT), and oxygenation index (OI) were calculated and compared. Seventy-five patients consented to participate in this study. Dynamic compliance, peak inspiratory pressure (PIP), and plateau inspiratory pressure (Pplat) increased after PEEP titration during OLV. PIP, Qs/ Qt, and OI showed no differences among groups. Group PDYN showed lower Pplat, lower driving pressure, and higher dynamic compliance when compared with zero PEEP group. The PEEP titrating strategy according to dynamic compliance can improve respiratory mechanics, whereas it has no significant effects on oxygenation, dead space ratio, and intrapulmonary shunt, suggesting that it is better during OLV for thoracic surgery.

The Effect of Fiberoptic Bronchoscopy-guided Technique for Placement of a Left-sided Double-lumen Tube on the Intubation Performance Compared with the Conventional Method Using a Macintosh Laryngoscope

Background: The accurate placement of the double-lumen endotracheal tube is imperative for effective one-lung ventilation in thoracic surgery. Malpositioning and repositioning of a misplaced tube may cause excessive trauma. Objective: We hypothesized that the fiberoptic bronchoscope-guided method for double-lumen endotracheal tube placement would reduce the incidence of malpositioning as compared to the conventional method using the Macintosh laryngoscope. Methods: Fifty patients scheduled to undergo elective thoracic surgery were recruited and randomly assigned to the fiberoptic bronchoscope-guided [n=25; Group F] and conventional [n=25; Group C] method groups, according to the method of double-lumen endotracheal tube placement. The primary outcome was the incidence of double-lumen endotracheal tube malpositioning observed under the fiberoptic bronchoscope after initial placement. Secondary outcomes included the times for placement, confirmation, and total procedure of double-lumen endotracheal tube intubation. Results: The incidence of malpositioning after initial double-lumen endotracheal tube placement was significantly lower in Group F than in Group C (20.0% vs 68.0%). In addition, the time for placement was significantly higher in Group F than in Group C, and that for confirmation was significantly lower in Group F than in Group C. Conclusion: The fiberoptic bronchoscope-guided method for double-lumen endotracheal tube placement can reduce the incidence of malpositioning after initial placement and expedite the intubation process with a double-lumen endotracheal tube in thoracic surgery.

An Update on One-Lung Ventilation in Children.

One-lung ventilation in children continues to present technical and sometimes physiologic challenges to the clinician. The rarity of these cases at any single institution, however, has led to very few prospective trials to guide best practices. As a result, most clinicians continue to be guided by local tradition and preference. That said, the development of new bronchial blockers such as the EZ-Blocker or blocking devices such as the Univent tube have continued to evolve the practice of lung isolation in children. Further, the development of a variety of extraluminal blocker techniques has led to innovations in practice through a relatively diverse landscape of published case series offering different approaches to one-lung ventilation during the past 15 years. The Arndt bronchial blocker continues to represent the most well documented of these devices. Additionally, recent advances have occurred in our understanding of the relevant anatomic constraints of the lower pediatric airway. This review is intended to provide a comprehensive and practical update to practicing pediatric anesthesiologists to further their understanding of the modern practice of one-lung ventilation for thoracic surgery in children.

Effect of Dexmedetomidine Combined with Inhalation of Isoflurane on Oxygenation Following One-Lung Ventilation in Thoracic Surgery.

BackgroundOne-lung ventilation (OLV) is commonly used during thoracic surgery. At this time, hypoxemia is considered one of the remarkable consequences of the anesthesia management. Hypoxic pulmonary vasoconstriction (HPV) is the defense mechanism against hypoxia.ObjectivesThe aim of the present study was to investigate the effect of infusion of dexmedetomidine on improving the oxygenation during OLV among the adult patients undergoing thoracic surgery.MethodsA total of 42 patients undergoing OLV by general anesthesia with isoflurane inhalation were randomly assigned into two groups: IV infusion of dexmedetomidine at 0.3 microgram/kg/h (DISO) and IV infusion of normal saline (NISO). Three Arterial Blood Gas (ABG) samples were obtained throughout the surgery. Hemodynamic parameters, PaO2, PaCO2, and complications at recovery phase were recorded. The collected information was analyzed using SPSS software version 22.ResultsIn the dexmedetomidine group, the mean hemodynamic parameters had a significant reduction at 30 and 60 minutes following OLV. Administration of dexmedetomidine resulted in a significant increase in the PaCO2 and a reduction in the PaO2 when changing from two-lung ventilation to OLV, where PaO2 reached its maximum value within 10 minutes after OLV in the DISO group, and it began to gradually increase to the end of operation. The duration of the recovery phase, also complications at the recovery phase decreased significantly in DISO group.ConclusionsThe results of the study showed that, dexmedetomidine may improve arterial oxygenation during OLV in adult patients undergoing thoracic surgery, and can be a suitable anesthetic agent for thoracic surgery.

Protective ventilation with high versus low positive end-expiratory pressure during one-lung ventilation for thoracic surgery (PROTHOR): study protocol for a randomized controlled trial

BackgroundPostoperative pulmonary complications (PPC) may result in longer duration of in-hospital stay and even mortality. Both thoracic surgery and intraoperative mechanical ventilation settings add considerably to the risk of PPC. It is unclear if one-lung ventilation (OLV) for thoracic surgery with a strategy of intraoperative high positive end-expiratory pressure (PEEP) and recruitment maneuvers (RM) reduces PPC, compared to low PEEP without RM.MethodsPROTHOR is an international, multicenter, randomized, controlled, assessor-blinded, two-arm trial initiated by investigators of the PROtective VEntilation NETwork. In total, 2378 patients will be randomly assigned to one of two different intraoperative mechanical ventilation strategies. Investigators screen patients aged 18 years or older, scheduled for open thoracic or video-assisted thoracoscopic surgery under general anesthesia requiring OLV, with a maximal body mass index of 35 kg/m2, and a planned duration of surgery of more than 60 min. Further, the expected duration of OLV shall be longer than two-lung ventilation, and lung separation is planned with a double lumen tube. Patients will be randomly assigned to PEEP of 10 cmH2O with lung RM, or PEEP of 5 cmH2O without RM. During two-lung ventilation tidal volume is set at 7 mL/kg predicted body weight and, during OLV, it will be decreased to 5 mL/kg. The occurrence of PPC will be recorded as a collapsed composite of single adverse pulmonary events and represents the primary endpoint.DiscussionPROTHOR is the first randomized controlled trial in patients undergoing thoracic surgery with OLV that is adequately powered to compare the effects of intraoperative high PEEP with RM versus low PEEP without RM on PPC. The results of the PROTHOR trial will support anesthesiologists in their decision to set intraoperative PEEP during protective ventilation for OLV in thoracic surgery.Trial registrationThe trial was registered in clinicaltrials.gov (NCT02963025) on 15 November 2016.

A novel technique for endobronchial blocker placement for one-lung ventilation in children under 2 years.

The present study aimed to report our clinical experience with intraluminal calculated distance for endobronchial blocker placement (ICEB) and to find out whether ICEB could reduce the number of hypoxemia episodes during blocker placement compared with extraluminal blocker placement for one-lung ventilation in children under the age of 2years. The medical records of all children under the age of 2years with a 5 French (F) or 4F WeiLi (WeiLi medical Inc, Guangzhou, China) endobronchial blocker for one-lung ventilation in thoracic surgery from July 2015 through July 2016 were retrospectively reviewed. After November 2015, one-lung ventilation was achieved using the ICEB technique, while before November 2015, extraluminal blocker placement was used. The success rate of blocker placement, quality of lung deflation, number of hypoxemia episodes, blocker dislodgement, and successful reposition after dislodgement were compared between the two groups. The incidence of hypoxemia episodes during blocker placement was lower in the ICEB group compared to the extraluminal placement group. Moreover, the success rate of blocker reposition during the operation was higher in the ICEB group than the extraluminal placement group. The success rate of endobronchial blocker placement was similar between the two groups. Intraluminal calculated distance for endobronchial blocker placement is a feasible method to achieve lung isolation and could reduce hypoxemia episodes during blocker placement in children under the age of 2years.

Effect of propofol and isoflurane on gas exchange parameters following one-lung ventilation in thoracic surgery: a double-blinded randomized controlled clinical trial.

BackgroundThe use of anesthetic drugs with minimal inhibitory effects on the hypoxic pulmonary vasoconstriction (HPV) could have a decisive role in preventing the hypoxemia during one-lung ventilation (OLV).ObjectiveThe aim of this study was to compare the effects of propofol and isoflurane on the changes in gas exchange parameters following OLV in thoracic surgery.MethodsThis double-blinded randomized controlled clinical trial was conducted on patients who were candidates for elective right thoracotomy referred to the central operating room of Ghaem Hospital in Mashhad, Iran, during February 2016–2017. Patients with age range of 18 to 75 years, class I and II American Society of Anesthesiologists (ASA) and thoracotomy with OLV for pulmonary resection or cyst drainage were included. The patients were randomly allocated (1:1 ratio) into two groups of propofol (P, 50–100μg/kg/min) and isoflurane (I, 1 minimum alveolar concentration (MAC) 1.1%). Partial pressure of carbon dioxide (PaCO2), partial pressure of oxygen (PaO2), end-tidal carbon dioxide (ETCO2) and arterial oxygen saturation (SPO2) were recorded before and 15 minutes after OLV and compared between the two groups. The comparison of the mean gas exchange parameters before and 15 minutes after OLV was performed using Mann-Whitney test in SPSS version 19 software. P<0.05 was considered statistically significant.ResultsIn this study, 122 patients with mean age of 59.4±14.1 years (two groups of 61) were studied. Both groups were matched for age or gender. The two groups had no significant difference in the gas exchange parameters before the OLV. Only PaCO2 (p=0.001) and ETCO2 (p=0.001) were significantly higher in the propofol group after 15 minutes OLV than in the isoflurane group. However, PaO2 (p=0.67), O2Sat (p=0.333) and PaCO2-ETCO2 gradient (p=0.809) showed no significant difference between the two groups at this minute.ConclusionBased on the results of this study, the propofol or isoflurane selection seems to have no significant effect on the arterial oxygenation. On the other hand, isoflurane and propofol could be an appropriate anesthetic for thoracic surgery by normalizing the carbon dioxide gradient range during the OLV.Clinical Trial RegistrationThe study was also registered at the Iranian Registry of Clinical Trials (IRCT2015123013159N8).FundingThe study was financially supported by the Deputy of Research of Mashhad University of Medical Sciences (grant number: 940119).

Bronchial blocker positioning: learning curve and confidence in its use.

Despite being simple and safe to use and cheap, EZ blocker (EZB) remains underused probably because it requires particular skills in recognizing airway and in using fiber-bronchoscopy to check the exact position of their cuffs. Thus, we planned an education training program on the use of EZB for novices in anesthesia and evaluated the number of procedures required for the acquisition of the skills of this technique. The educational training program included three different phases as follows. The first phase included a lecture on the utility of one-lung ventilation in thoracic surgery, on the use of the fiber- bronchoscopy and on the characteristics of EZB. The second phase consisted in a practical teaching course performed on a manikin model to acquire the skills in EZB. The third phase was a clinical training where each participant performed a defined number in patients scheduled for thoracic surgery procedures. The acquisition of dexterity and satisfaction were then statistically valuated. The dexterity in placing EZB significantly increased after six attempts (P<0.1). Participants acquired skills in correcting position EZB after 15 attempts. Participants increased their level of confidence with EZB (score 5.7±1.3) and were highly satisfied with the training received (score 5.8±1.6). EZB is a valid strategy for obtaining one lung ventilation. Thus, it should be included in the armamentarium of all anesthetists interested in the field of thoracic surgery. Our teaching course seems to be a valuable method to instill easily and speedily in training novices in anesthesia the skills in placing EZB.

Comparison of Arndt-endobronchial blocker plus laryngeal mask airway with left-sided double-lumen endobronchial tube in one-lung ventilation in thoracic surgery in the morbidly obese.

This study aimed to evaluate the feasibility and performance of Arndt-endobronchial blocker (Arndt) combined with laryngeal mask airway (LMA) compared with left-sided double-lumen endobronchial tube (L-DLT) in morbidly obese patients in one-lung ventilation (OLV). In a prospective, randomized double-blind controlled clinical trial, 80 morbidly obese patients (ASA I-III, aged 20–70) undergoing general anesthesia for elective thoracic surgeries were randomly allocated into groups Arndt (n=40) and L-DLT (n=40). In group Arndt, a LMA™ Proseal was placed followed by an Arndt-endobronchial blocker. In group L-DLT, patients were intubated with a left-sided double-lumen endotracheal tube. Primary endpoints were the airway establishment, ease of insertion, oxygenation, lung collapse and surgical field exposure. Results showed similar ease of airway establishment and tube/device insertion between the two groups. Oxygen arterial pressure (PaO2) of patients in the Arndt group was significantly higher than L-DLT (154±46 vs 105±52 mmHg; P<0.05). Quality of lung collapse and surgical field exposure in the Arndt group was significantly better than L-DLT (effective rate 100 vs 90%; P<0.05). Duration of surgery and anesthesia were significantly shorter in the Arndt group (2.4±1.7 vs 3.1±1.8 and 2.8±1.9 vs 3.8±1.8 h, respectively; P<0.05). Incidence of hoarseness of voice and incidence and severity of throat pain at the post-anesthesia care unit and 12, 24, 48, and 72 h after surgery were significantly lower in the Arndt group (P<0.05). Findings suggested that Arndt-endobronchial blocker combined with LMA can serve as a promising alternative for morbidly obese patients in OLV in thoracic surgery.

Effects of Dexmedetomidine Infusion on Inflammatory Responses and Injury of Lung Tidal Volume Changes during One-Lung Ventilation in Thoracoscopic Surgery: A Randomized Controlled Trial

One-lung ventilation in thoracic surgery provokes profound systemic inflammatory responses and injury related to lung tidal volume changes. We hypothesized that the highly selective a2-adrenergic agonist dexmedetomidine attenuates these injurious responses. Sixty patients were randomly assigned to receive dexmedetomidine or saline during thoracoscopic surgery. There is a trend of less postoperative medical complication including that no patients in the dexmedetomidine group developed postoperative medical complications, whereas four patients in the saline group did (0% versus 13.3%, p = 0.1124). Plasma inflammatory and injurious biomarkers between the baseline and after resumption of two-lung ventilation were particularly notable. The plasma high-mobility group box 1 level decreased significantly from 51.7 (58.1) to 33.9 (45.0) ng.ml−1 (p < 0.05) in the dexmedetomidine group, which was not observed in the saline group. Plasma monocyte chemoattractant protein 1 [151.8 (115.1) to 235.2 (186.9) pg.ml−1, p < 0.05] and neutrophil elastase [350.8 (154.5) to 421.9 (106.1) ng.ml−1, p < 0.05] increased significantly only in the saline group. In addition, plasma interleukin-6 was higher in the saline group than in the dexmedetomidine group at postoperative day 1 [118.8 (68.8) versus 78.5 (58.8) pg.ml−1, p = 0.0271]. We conclude that dexmedetomidine attenuates one-lung ventilation-associated inflammatory and injurious responses by inhibiting alveolar neutrophil recruitment in thoracoscopic surgery.

Factors Influencing Regional Cerebral Oxygen Saturation during One-lung Ventilation in Thoracic Surgery.

Objective To identify factors influencing regional cerebral oxygen saturation (rScO2) during one-lung ventilation (OLV) in thoracic surgery. Methods Totally 33 patients with an ASA physical status of 1-3 scheduled for elective thoracic surgery with one-lung ventilation under general anesthesia were recruited. After anesthesia was induced with propofol,fentanyl/sufentanil,and rocuronium. All patients received balanced anesthesia using sevoflurane. During OLV,volume-controlled ventilation was used with a tidal volume of 6-7 ml/kg and an inspiration:expiration ratio of 1:1.5. The ventilator frequency was adjusted with a target end-tidal carbon dioxide partial pressure (PetCO2) between 35 mmHg and 45 mmHg. During the anesthesia,patients were maintained at a pulse oxygen saturation (SpO2) of>90%,systolic blood pressure (SBP) of>90 mmHg (or reducing no more than 30% of the basic values),heart rate (HR) of>50 beat/min,and hemoglobin concentration of>90 g/L. Changes of rScO2 were monitored with FORESIGHT probes by specialized researchers. Patients were classified into low rScO2 (L-rScO2) group (n=10) or high rScO2 (H-rScO2)group(n=23) according to whether the lowest intraoperative rScO2 was under 65% or 15% lower than the baseline values. We compared gender,age,body mass index (BMI),intraoperative hemoglobin level,and the values of peak airway pressure (Ppeak),SBP,PetCO2,and SpO2 when rScO2 dropped to the lowest level between these two groups. Results Statistically higher Ppeak and lower SBP were noted in the L-rScO2 group compared with H-rScO2 group (P=0.028,P=0.046). SpO2 was lower in the L-rScO2 group compared with H-rScO2 group,but the difference was not statistically significant (P=0.421). There was also no significant difference between the two groups according to age,BMI,SpO2,PetCO2,or hemoglobin level. Ppeak appeared to be a risk factor for rScO2 reduction during OLV,as shown by unconditioned Logistic regression analysis. Conclusion During OLV in thoracic surgery,Ppeak is a risk factor for rScO2 reduction.

Apneic oxygen insufflation decreases the incidence of hypoxemia during one-lung ventilation in open and thoracoscopic pulmonary lobectomy: A randomized controlled trial

ObjectiveHypoxemia is common during one-lung ventilation (OLV) for thoracic surgery. When hypoxemia occurs, surgery is interrupted for rescue ventilation. Apneic oxygen insufflation (AOI), which provides O2 without applying pressure, may prevent hypoxemia and does not interrupt surgery. The aim of this study was to determine the effectiveness of the AOI technique for preventing hypoxemia during OLV in thoracic surgery. MethodsPatients undergoing open or thoracoscopic pulmonary lobectomy from September to December 2015 were included. Patients were assigned randomly to a non-AOI group or an AOI group (n = 45 each). OLV was initiated and at the 15-minute mark (OLV15), patients in the AOI group received oxygen insufflation at 3 L/min to the nonventilated lung for 30 minutes (OLV45). The primary endpoint was the occurrence of hypoxemia (SaO2 <90%) during OLV. ResultsThe demographic and operative data were similar between the 2 groups. The incidence of hypoxemia was greater in the non-AOI than the AOI group (18% vs 0%; P = .009). ΔPaO2 (the difference in partial pressure of oxygen in arterial blood between OLV 45 and 15 minutes) was smaller in the AOI than the non-AOI group (−29 mm Hg vs −69 mm Hg; P = .005). Duration of surgery and incidence of complications did not vary between groups. ConclusionsAOI decreases the incidence of hypoxemia and improves arterial oxygenation during OLV for open and thoracoscopic surgery. AOI may be a valuable option to prevent hypoxemia. It can be used before relying on continuous positive airway pressure or intermittent two-lung ventilation and result in fewer interruptions in surgery.

Unusual airways management during one-lung ventilation in thoracic surgery

Airways management in thoracic surgery is usually more difficult than in other surgery. We reported a case of a patient who underwent surgery of evacuation of empyema where after a correct insertion of a left double-lumen tube 37 Fr (DLT), one-lung ventilation was not permitted by the high airways pressure. In fact, the hole of bronchial tip was just against the left bronchial wall retracted probably from inflammatory process. We introduced blindly an Arndt blocker 9 Fr inside the tracheal lumen of DLT until the orifice of the right upper lobe bronchus, the distance was checked before. After the positioning of the blocker, the DLT was pulled up to above the carina, and the single-lung ventilation was permitted. Sometimes, an unusual use of different devices permits to manage complications. In fact, in this case, the Arndt bronchial blocker helps us to solve an important ventilatory problem.

Lung re-inflation after one-lung ventilation for thoracic surgery: an alternative technique

Lung re-inflation after one-lung ventilation for thoracic surgery: an alternative technique

A novel combination of the Arndt endobronchial blocker and the laryngeal mask airway ProSeal™ provides one-lung ventilation for thoracic surgery.

In this study, the feasibility and performance of the combination of the Arndt endobronchial blocker and the laryngeal mask airway (LMA) ProSeal™ in airway establishment, ventilation, oxygenation and lung isolation was evaluated. Fifty-five patients undergoing general anesthesia for elective thoracic surgeries were randomly allocated to group Arndt (n=26) or group double-lumen tube (DLT; n=29). Data concerning post-operative airway morbidity, ease of insertion, hemodynamics, lung collapse, ventilators, oxygenation and ventilation were collected for analysis. Compared with group DLT, group Arndt showed a significantly attenuated hemodynamic response to intubation (blood pressure, 149±31 vs. 115±16 mmHg; heart rate, 86±15 vs. 68±15 bpm), less severe injuries to the bronchus (injury score, 1.4±0.2 vs. 0.4±0.1) and vocal cords (injury score, 1.3±0.2 vs. 0.6±0.1), and lower incidences of post-operative sore throat and hoarseness. Furthermore, the novel combination of the Arndt and the LMA ProSeal showed similar ease of airway establishment, comparable ventilation and oxygenation performance, and an analogous lung isolation effect to DLT. The novel combined use of the Arndt endobronchial blocker and the LMA ProSeal can serve as a promising alternative for thoracic procedures requiring one-lung ventilation. The less traumatic properties and equally ideal lung isolation are likely to promote its use in rapidly spreading minimally invasive thoracic surgeries.

Lung re-inflation after one-lung ventilation for thoracic surgery: importance of clamping the dependent lung

To the Editor, Our thoracic surgeons routinely request that continuous positive airway pressure (CPAP) be applied to the nondependent (i.e., operated on) lung either to test the bronchial staple line after resection or to ensure lung reexpansion prior to chest closure. Although we generally use low airway pressure (i.e., 15 cm H2O), at times up to 30 cm H2O is needed to expand portions of the lung that have been chronically atelectatic. Application of these pressures to both lungs may result in the relatively compliant dependent lung receiving a greater proportion of the gas flow, which can increase its risk of volutrauma. In addition, prolonged inflation with relatively high pressures can excessively increase intrathoracic pressure and even result in a mediastinal shift, each of which can reduce venous return and lead to hypotension. In order to reduce these consequences, prior to applying the CPAP, we suspend ventilation and clamp the dependent lung lumen of the double-lumen endotracheal tube, thereby stopping gas flow to that lung. This measure not only protects the dependent lung from the high airway pressures, but also reduces the duration of CPAP application by expanding the non-dependent lung more rapidly, and thus decreases the risk of prolonged reduction in venous return. Although clamping the dependent lung prior to applying CPAP to the operative lung is not a novel technique, it has come to our attention that many anesthesiologists have not considered it. Indeed, residents who have come to our hospital for exposure to community anesthesia practice frequently note that this technique has not been taught in their training programs. Also, after observing the technique, they have expressed appreciation of its advantages. A potential objection to clamping flow to the dependent lung during a CPAP test is the potential to subjecting the patient to the risk of hypoxemia or hypercapnea. We have not found this been an issue, however. If anything, oxygen saturation improves as the alveoli are opened. Also, suspending ventilation for less than the minute it usually takes to re-expand the lung is unlikely to increase CO2 to any significant degree. Importantly, we have not observed hypotension during re-inflation using this lung-clamping CPAP technique. Despite the fact that there have been no clinical studies to determine that any one technique for lung re-expansion provides better results than any other, we think that this technique is a logical and relatively safe method to prevent potential volutrauma and/or hypotension.

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

BackgroundThe 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.MethodsForty-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).ResultsOxygen 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).ConclusionsIn 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.

The effects of prolonged inspiratory time during one‐lung ventilation: a randomised controlled trial

We evaluated the effects of a prolonged inspiratory time on gas exchange in subjects undergoing one-lung ventilation for thoracic surgery. One hundred patients were randomly assigned to Group I:E = 1:2 or Group I:E = 1:1. Arterial blood gas analysis and respiratory mechanics measurements were performed 10 min after anaesthesia induction, 30 and 60 min after initiation of one-lung ventilation, and 15 min after restoration of conventional two-lung ventilation. The mean (SD) ratio of the partial pressure of arterial oxygen to fraction of inspired oxygen after 60 min of one-lung ventilation was significantly lower in Group I:E = 1:2 compared with Group I:E = 1:1 (27.7 (13.2) kPa vs 35.2 (22.1) kPa, respectively, p = 0.043). Mean (SD) physiological dead space-to-tidal volume ratio after 60 min of one-lung ventilation was significantly higher in Group I:E = 1:2 compared with Group I:E = 1:1 (0.46 (0.04) vs 0.43 (0.04), respectively, p = 0.008). Median (IQR [range]) peak inspiratory pressure was higher in Group I:E = 1:2 compared with Group I:E = 1:1 after 60 min of one-lung ventilation (23 (22-25 [18-29]) cmH2O vs 20 (18-21 [16-27]) cmH2O, respectively, p < 0.001) and median (IQR [range]) mean airway pressure was lower in Group I:E = 1:2 compared with Group I:E = 1:1 (10 (8-11 [5-15]) cmH2O vs 11 (10-13 [5-16]) cmH2O, respectively, p < 0.001). We conclude that, compared with an I:E ratio of 1:2, an I:E ratio of 1:1 resulted in a modest improvement in oxygenation and decreased shunt fraction during one-lung ventilation.