Comparison of volume controlled with pressure controlled ventilation during one-lung anaesthesia

Comparison of pressure controlled, volume controlled, and volume guaranteed pressure controlled modes in prone position in patients operated for lumbar disc herniation: A randomized trial

BACKGROUND

To compare pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), and pressure-controlled ventilation-volume guaranteed (PCV-VG) modes in patients undergoing spinal surgery in the prone position under general anesthesia.

METHODS

The study included 78 patients aged 20 to 80 years, American Society of Anesthesiologists 1-2, scheduled for lumbar spinal surgery. Patients included in the study were randomly divided into 3 groups Group-VCV; Group-PCV; Group-PCV-VG. Standard anesthesia protocol was applied. In addition to routine monitoring, train of four and BIS monitoring were performed. All ventilation modes were set with a target tidal volume of 6 to 8 mL/kg, FiO2: 0.40-0.45 and a respiratory rate of normocarbia. Positive end-expiratory pressure: 5 cm H2O, inspiration/expiration ratio = 1:2, and the maximum airway pressure:40 cm H2O. Hemodynamic, respiratory variables and arterial blood gases was measured, 15 minutes after induction of anesthesia in the supine position (T1), after prone position 15 minutes (T2), 30 minutes (T3), 45 minutes (T4), 60 minutes (T5), 75 minutes (T6), 90 minutes (T7).

RESULTS

There was no significant difference between the groups in patient characteristics. SAP, DAP, mean arterial pressure, and heart rate decreased after being placed in the prone position in all groups. Hemodynamic variables did not differ significantly between the groups. partial arterial oxygen pressure and arterial oxygen saturation levels in blood gas were found to be significantly higher in Group-PCV-VG compared to Group-PCV and Group-VCV in both the supine and prone positions. Ppeak and plateau airway pressure (Pplato) values increased and dynamic lung compliance (Cdyn) values decreased after placing the patients in the prone position in all groups. Lower Ppeak and Pplato values and higher Cdyn values were observed in both the supine and prone positions in the Group-PCV-VG group compared to the Group-PCV and Group-VCV groups.

CONCLUSION

PCV-VG provides lower Ppeak and Pplato values, as well as better Cdyn, oxygenation values compared to PCV and VCV. So that PCV-VG may be an effective alternative mode of mechanical ventilation for patients in the prone position during lumbar spine surgery.

Comparative study of ventilation techniques with supraglottic airway devices in cats: volume-controlled vs pressure-controlled techniques

OBJECTIVES

This study compared the effectiveness of a new supraglottic airway device (SGAD) in cats undergoing anaesthesia using two types of mechanical ventilation: volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV).

METHODS

A total of 13 healthy cats (five male, eight female; median age 2 years [range 1-3]) were randomly allocated to either VCV or PCV. Five tidal volumes (6, 8, 10, 12 and 14 ml/kg) and five peak inspiratory pressures (4, 5, 6, 7 and 8 cmH2O) were randomly applied with a minute ventilation of 100 ml/kg/min. Various parameters, such as blood pressure, gas leakage, end-tidal CO2 (ETCO2) and work of breathing (WOB), were measured while using VCV or PCV.

RESULTS

The occurrence of hypotension (mean arterial blood pressure <60 mmHg) was slightly less frequent with VCV (38 events, 65 ventilating sessions) than with PCV (40 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.429). The number of leakages did not differ between the VCV group (3 events, 65 ventilating sessions) and the PCV group (3 events, 65 ventilating sessions) (P = 1.000). Hypercapnia was identified when using VCV (10 events, 65 ventilating sessions) less frequently than when using PCV (17 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.194). The study found a significantly higher WOB in the PCV group compared with the VCV group (P <0.034).

CONCLUSIONS AND RELEVANCE

The present results suggested that both VCV and PCV can be used with an SGAD during anaesthesia, with VCV preferred for prolonged mechanical ventilation due to its lower workload. Adjusting tidal volume or inspiratory pressure corrects hypercapnia.

Clinical guide to perioperative management for videothoracoscopy lung resection (Section of Cardiac, Vascular and Thoracic Anesthesia, SEDAR; Spanish Society of Thoracic Surgery, SECT; Spanish Society of Physiotherapy)

The introduction of video-assisted thoracoscopic (VATS) techniques has led to a new approach in thoracic surgery. VATS is performed by inserting a thoracoscope through a small incisions in the chest wall, thus maximizing the preservation of muscle and tissue. Because of its low rate of morbidity and mortality, VATS is currently the technique of choice in most thoracic procedures. Lung resection by VATS reduces prolonged air leaks, arrhythmia, pneumonia, postoperative pain and inflammatory markers. This reduction in postoperative complications shortens hospital length of stay, and is particularly beneficial in high-risk patients with low tolerance to thoracotomy. Compared with conventional thoracotomy, the oncological results of VATS surgery are similar or even superior to those of open surgery. This aim of this multidisciplinary position statement produced by the thoracic surgery working group of the Spanish Society of Anesthesiology and Reanimation (SEDAR), the Spanish Society of Thoracic Surgery (SECT), and the Spanish Association of Physiotherapy (AEF) is to standardize and disseminate a series of perioperative anaesthesia management guidelines for patients undergoing VATS lung resection surgery. Each recommendation is based on an in-depth review of the available literature by the authors. In this document, the care of patients undergoing VATS surgery is organized in sections, starting with the surgical approach, and followed by the three pillars of anaesthesia management: preoperative, intraoperative, and postoperative anaesthesia.

The role of mechanical ventilation in primary graft dysfunction in the postoperative lung transplant recipient: A single center study and literature review

Background

Primary graft dysfunction (PGD) is still a major complication in patients undergoing lung transplantation (LTx). Much is unknown about the effect of postoperative mechanical ventilation on outcomes, with debate on the best approach to ventilation.

Aim/Purpose

The goal of this study was to generate hypotheses on the association between postoperative mechanical ventilation settings and allograft size matching in PGD development.

Method

This is a retrospective study of LTx patients between September 2011 and September 2018 (n = 116). PGD was assessed according to the International Society of Heart and Lung Transplantation (ISHLT) criteria. Data were collected from medical records, including chest x‐ray assessments, blood gas analysis, mechanical ventilator parameters and spirometry.

Results

Positive end‐expiratory pressures (PEEP) of 5 cm H₂O were correlated with lower rates of grade 3 PGD. Graft size was important as tidal volumes calculated according to the recipient yielded greater rates of PGD when low volumes were used, a correlation that was lost when donor metrics were used.

Conclusion

Our results highlight a need for greater investigation of the role donor characteristics play in determining post‐operative ventilation of a lung transplant recipient. The mechanical ventilation settings on postoperative LTx recipients may have an implication for the development of acute graft dysfunction. Severe PGD was associated with the use of a PEEP higher than 5 and lower tidal volumes and oversized lungs were associated with lower long‐term mortality. Lack of association between ventilatory settings and survival may point to the importance of other variables than ventilation in the development of PGD.

Recommendations of the Society of Thoracic Surgery and the Section of Cardiothoracic and Vascular Surgery of the Spanish Society of Anesthesia, Resuscitation and Pain Therapy, for patients undergoing lung surgery included in an intensified recovery program

In recent years, multidisciplinary programs have been implemented that include different actions during the pre, intra and postoperative period, aimed at reducing perioperative stress and therefore improving the results of patients undergoing surgical interventions. Initially, these programs were developed for colorectal surgery and from there they have been extended to other surgeries. Thoracic surgery, considered highly complex, like other surgeries with a high postoperative morbidity and mortality rate, may be one of the specialties that most benefit from the implementation of these programs. This review presents the recommendations made by different specialties involved in the perioperative care of patients who require resection of a lung tumor. Meta-analyzes, systematic reviews, randomized and non-randomized controlled studies, and retrospective studies conducted in patients undergoing this type of intervention have been taken into account in preparing the recommendations presented in this guide. The GRADE scale has been used to classify the recommendations, assessing on the one hand the level of evidence published on each specific aspect and, on the other hand, the strength of the recommendation with which the authors propose its application. The recommendations considered most important for this type of surgery are those that refer to pre-habilitation, minimization of surgical aggression, excellence in the management of perioperative pain and postoperative care aimed at providing rapid postoperative rehabilitation.

Effect of different mechanical ventilation modes on cerebral blood flow during thoracoscopic surgery in neonates: A randomised controlled trial

Background and Aims:

Infants exposed to major surgery are at risk of injuries to the immature brain because of reduced arterial oxygen saturation. This study compared the effect of volume-controlled ventilation (VCV) versus pressure-controlled ventilation (PCV) on cerebral oxygenation in neonates subjected to repair of tracheoesophageal fistula (TEF) under video-assisted thoracoscopic surgery (VATS).

Methods:

This randomised controlled study included 30 full-term neonates scheduled for VATS for managing TEF under general anaesthesia. They were randomised to either VC group (n = 15), who received VCV, or PC group (n = 15), who received PCV. Cerebral oxygenation (rScO₂) was monitored throughout the surgery with documentation of episodes of cerebral desaturation. Peripheral oxygen saturation, partial pressure of carbon dioxide (PaCO₂), and end-tidal carbon dioxide were recorded at baseline, after induction of anaesthesia, and every 30 min till the end of the surgery.

Results:

rScO₂ was significantly higher in the PC group than the VC group at baseline and was significantly higher in the VC group after 15 min (P = 0.041). Later, it was comparable in both the groups up to 60 min after starting the surgery. Cerebral desaturation was significantly more common in the PC group (80%) compared to VC group (33.3%) (P = 0.010). PC group required higher fraction of inspired oxygen and positive end-expiratory pressure to prevent cerebral desaturation. PaCO₂ was significantly higher in the PC group than the VC group at 30 and 60 min (P = 0.005 and 0.029).

Conclusion:

VCV is safer than PCV for cerebral oxygenation during VATS in neonates.

Effects of pressure- and volume-controlled ventilation on the work of breathing in cats using a cuffed endotracheal tube

Background and Aim:

Mechanical ventilation is essential for supporting patients’ respiratory function when they are under general anesthesia. For cats with limited lung capacity, the different effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on respiratory function remain elusive. The objective of the present study was to compare the efficacy of VCV and PCV in cats under general anesthesia using a cuffed endotracheal tube (ETT).

Materials and Methods:

Twelve healthy cats were randomly allocated to either a VCV or PCV group. Five tidal volumes (6, 8, 10, 12, and 14 mL/kg) were randomly applied to assess the efficacy of VCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Peak inspiratory pressures (4, 5, 6, 7, and 8 mmHg) were randomly applied to assess the efficacy of PCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Blood pressure, gas leakages, and end-tidal CO₂ were recorded from 60 trials for airway control during the use of VCV or PCV. Data were compared using Fisher’s exact test with a significance level of p<0.05.

Results:

Leakages did not differ between VCV (1/60 events) and PCV (0/60 events; p=0.500). Hypercapnia was identified when using VCV (6/60 events) less frequently than when using PCV (7/60 events; p=0.762), but did not reach statistical significance. Hypotension (mean arterial blood pressure <60 mmHg) occurred less frequently with VCV (0/60 events) than with PCV (9/60 events; p=0.003). Moreover, VCV provided a significantly lower work of breathing (151.10±65.40 cmH₂O mL) compared with PCV (187.84±89.72 cmH₂O mL; p<0.05).

Conclusion:

VCV in cats using a cuffed ETT causes less hypotension than PCV. It should be noted that VCV provides a more stable tidal volume compared with PCV, resulting in a more stable minute volume. Nonetheless, VCV should not be used in patients with an airway obstruction because higher peak airway pressure may occur and lead to lung injury.

Anesthetic management of thoracoscopic procedures in neonates: a retrospective analysis of 45 cases

BACKGROUND

Advances in medical techniques and equipment have enabled the thoracoscopic repair of certain congenital abnormalities in neonates including congenital esophageal atresia/tracheoesophageal fistula (EA/TEF) and congenital diaphragmatic hernia (CDH). A retrospective analysis was conducted to examine the anesthetic management of neonates (7 days or younger) undergoing thoracoscopic surgery in our hospital department, and to determine the efficacy of anesthetic management in neonates.

METHODS

Clinical data from 45 neonates who underwent thoracoscopic surgery in our hospital from December 2015 to March 2020 were retrospectively analyzed. A total of 25 patients underwent repair of CDH and 20 underwent repair of an EA/TEF.

RESULTS

All patients received general anesthesia with endotracheal intubation, standard ASA monitoring, and arterial blood gas (ABG) analysis. All patients survived the surgery. A total of 14 patients experienced decreases in SpO₂, pH, PaO₂, and increases in P_ETCO₂ and PaCO₂ 30 minutes after CO₂ insufflation. Our anesthetic management protocols are outline and analyzed.

CONCLUSIONS

Thorough preoperative preparation is critical for a desirable outcome in neonates undergoing a thoracoscopic repair of CDH or EA/TEF. In our cohort, intraoperative ventilation strategies included pressure control ventilation with peak airway pressure maintained at 15-25 cmH₂O, a respiratory rate of 35-55 breaths/minute, a fraction of inspired oxygen (FiO₂) of 60-80%, an inspiratory/expiratory ratio (I:E) of 1:1-1.5, and careful airway suctioning to clear secretions. Postoperatively, maintaining normovolemia and hemodynamic stability are critical for successful weaning of ventilatory support and extubation.

Clinical guide to perioperative management for videothoracoscopy lung resection (Section of Cardiac, Vascular and Thoracic Anesthesia, SEDAR; Spanish Society of Thoracic Surgery, SECT; Spanish Society of Physiotherapy)

The introduction of video-assisted thoracoscopic (VATS) techniques has led to a new approach in thoracic surgery. VATS is performed by inserting a thoracoscope through a small incisions in the chest wall, thus maximizing the preservation of muscle and tissue. Because of its low rate of morbidity and mortality, VATS is currently the technique of choice in most thoracic procedures. Lung resection by VATS reduces prolonged air leaks, arrhythmia, pneumonia, postoperative pain and inflammatory markers. This reduction in postoperative complications shortens hospital length of stay, and is particularly beneficial in high-risk patients with low tolerance to thoracotomy. Compared with conventional thoracotomy, the oncological results of VATS surgery are similar or even superior to those of open surgery. This aim of this multidisciplinary position statement produced by the thoracic surgery working group of the Spanish Society of Anesthesiology and Reanimation (SEDAR), the Spanish Society of Thoracic Surgery (SECT), and the Spanish Association of Physiotherapy (AEF) is to standardize and disseminate a series of perioperative anaesthesia management guidelines for patients undergoing VATS lung resection surgery. Each recommendation is based on an in-depth review of the available literature by the authors. In this document, the care of patients undergoing VATS surgery is organized in sections, starting with the surgical approach, and followed by the three pillars of anaesthesia management: preoperative, intraoperative, and postoperative anaesthesia.

Recommendations of the Society of Thoracic Surgery and the Section of Cardiothoracic and Vascular Surgery of the Spanish Society of Anesthesia, Resuscitation and Pain Therapy, for patients undergoing lung surgery included in an intensified recovery program

In recent years, multidisciplinary programs have been implemented that include different actions during the pre, intra and postoperative period, aimed at reducing perioperative stress and therefore improving the results of patients undergoing surgical interventions. Initially, these programs were developed for colorectal surgery and from there they have been extended to other surgeries. Thoracic surgery, considered highly complex, like other surgeries with a high postoperative morbidity and mortality rate, may be one of the specialties that most benefit from the implementation of these programs. This review presents the recommendations made by different specialties involved in the perioperative care of patients who require resection of a lung tumor. Meta-analyses, systematic reviews, randomized and non-randomized controlled studies, and retrospective studies conducted in patients undergoing this type of intervention have been taken into account in preparing the recommendations presented in this guide. The GRADE scale has been used to classify the recommendations, assessing on the one hand the level of evidence published on each specific aspect and, on the other hand, the strength of the recommendation with which the authors propose its application. The recommendations considered most important for this type of surgery are those that refer to pre-habilitation, minimization of surgical aggression, excellence in the management of perioperative pain and postoperative care aimed at providing rapid postoperative rehabilitation.

[Intraoperative Ventilation Approaches to One-lung Ventilation]

The management of thoracic surgery patients is challenging to the anesthetist, since one-lung ventilation (OLV) includes at least two major conditions: sufficient oxygenation and lung protection. The first is mainly because the ventilation of one lung is stopped while perfusion to that lung continues; the latter is related to the fact that the whole ventilation is applied to only a single lung. Recommendations for maintaining the oxygenation and methods of lung protection may contradict each other (e. g. high vs. low inspiratory oxygen fraction (FiO₂), high vs. low tidal volume, etc.). Therefore, a high degree of pathophysiological understanding and manual skills are required in the management of these patients.In light of recent clinical studies, this review focuses on a current protective strategy for OLV, which includes a possible decrease in FiO₂, lowered V_T, the application of positive end-expiratory pressure (PEEP) to the dependent and continuous positive airway pressure (CPAP) to the non-dependent lung and alveolar recruitment manoeuvres as well. Other approaches such as the choice of anaesthetics, remote ischemic preconditioning, fluid management and pain therapy can support the success of ventilatory strategy. The present work describes new developments that may change the classical approach in this respect.

Effect of Pressure-Controlled Ventilation-Volume Guaranteed on One-Lung Ventilation in Elderly Patients Undergoing Thoracotomy

Background

Volume-controlled ventilation (VCV) in one-lung ventilation (OLV) is most commonly used in thoracotomy, but pressure-controlled ventilation-volume guaranteed (PCV-VG) is used in elderly patients to improve arterial oxygenation, reduce inflammatory factors, and decrease acute lung injury (ALI). The purpose of this study was to investigate the effects of these 2 different ventilation modes – VCV versus PCV-VG – during OLV in elderly patients undergoing thoracoscopic lobectomy.

Material/Methods

Sixty patients undergoing thoracoscopic lobectomy from September 2018 to February 2019 at Cangzhou Central Hospital, Hebei, China were randomly assigned to a VCV group or a PCV-VG group. Pulmonary dynamic compliance (Cdyn), peak inspiratory pressure (PIP), arterial blood gas, and inflammatory factors were monitored to assess lung function. The Clinical Trial Registration Identifier number is ChiCTR1800017835.

Results

Compared with the VCV group, PIP in the PCV-VG group was significantly lower (P=0.01) and Cdyn was significantly higher at 30 min after one-lung ventilation (P=0.01). MAP of the PCV-VG group was higher than in the VCV group (P=0.01). MAP of the PCV-VG group was also higher than in the VCV group at 30 min after one-lung ventilation (P=0.01). The concentration of neutrophil elastase (NE) in the PCV-VG group was significantly lower than in the VCV group (P=0.01).

Conclusions

Compared with VCV, PCV-VG mode reduced airway pressure in patients undergoing thoracotomy and also decreased the release of NE and reduced inflammatory response and lung injury. We conclude that PCV-VG mode can protect the lung function of elderly patients undergoing thoracotomy.

Volume-Controlled Versus Dual-Controlled Ventilation during Robot-Assisted Laparoscopic Prostatectomy with Steep Trendelenburg Position: A Randomized-Controlled Trial

Dual-controlled ventilation (DCV) combines the advantages of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Carbon dioxide (CO₂) pneumoperitoneum and steep Trendelenburg positioning for robot-assisted laparoscopic radical prostatectomy (RALRP) has negative effects on the respiratory system. We hypothesized that the use of autoflow as one type of DCV can reduce these effects during RALRP. Eighty patients undergoing RALRP were randomly assigned to receive VCV or DCV. Arterial oxygen tension (PaO₂) as the primary outcome, respiratory and hemodynamic data, and postoperative fever rates were compared at four time points: 10 min after anesthesia induction (T1), 30 and 60 min after the initiation of CO₂ pneumoperitoneum and Trendelenburg positioning (T2 and T3), and 10 min after supine positioning (T4). There were no significant differences in PaO₂ between the two groups. Mean peak airway pressure (Ppeak) was significantly lower in group DCV than in group VCV at T2 (mean difference, 5.0 cm H₂O; adjusted p < 0.001) and T3 (mean difference, 3.9 cm H₂O; adjusted p < 0.001). Postoperative fever occurring within the first 2 days after surgery was more common in group VCV (12%) than in group DCV (3%) (p = 0.022). Compared with VCV, DCV did not improve oxygenation during RALRP. However, DCV significantly decreased Ppeak without hemodynamic instability.

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

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±3.3 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.

Laparoscopic surgery: It is no necessary to change ventilator mode to improve ventilation conditions; a controlled trial

Backgrounds/Aims

The main objective of this study is to compare the ventilatory effects of AFVC and PC modes with the VC mode in laparoscopic surgery of the gall bladder.

Methods

Thirty-five patients programmed for laparoscopic cholecystectomy were included. Four times were defined for all patients. The parameters studied were recorded ten minutes after anesthetic induction; and this is the time T1. The time T2 fits to 10 min after induction of pneumoperitoneum. Then, the ventilator mode was changed from VC mode to AFVC mode. Ten minutes later, the variables were scored; it was the time T3. The ventilator mode was then changed to a PC mode. The set pressure was adjusted in order to obtain the same Vt as at the time T2. The time T4 was 10 minutes after switching to PC mode.

Results

The Vte were increased, compared to time T2, during the AFVC and PC modes. The induction of pneumoperitoneum with CO₂ induced a rise of P_ETCO₂ between T1 and T2. These had been accompanied by a significant rise in airway pressures. The change from VC mode to AFVC mode resulted in lower Prpeak and Prtray elevation without impacting dynamic compliance.

Conclusions

AFVC mode appears safe for patients in laparoscopic surgery. Its use, compared with VC, is associated with a decrease in Prpeak without effects on the Cdyn, oxygenation, capnia and hemodynamic parameters. We conclude that is no necessary to change ventlatory modes to improve ventilation conditions in non-obese patients.

Prevalence and clinical course of postoperative acute lung injury after esophagectomy for esophageal cancer

Background

Although acute lung injury (ALI) that develops after esophagectomy is associated with significant morbidity and mortality, there is limited information on its overall clinical course. The objective of this study was to investigate the prevalence and clinical course of ALI after esophagectomy.

Methods

Data were collected from all consecutive patients diagnosed with ALI after esophagectomy for esophageal cancer from January 2012 through March 2017 and retrospectively analyzed.

Results

During the study period, a total of 1,132 patients underwent esophagectomy for esophageal cancer and 52 (4.6%) patients developed postoperative ALI. At the time of ALI diagnosis, the median lung injury score of all patients was 1.8 (1.0-2.0). Among the patients with ALI, 17 (33%) patients required mechanical ventilation (MV) support, of which two failed to wean from MV and 15 were weaned from MV. The median MV duration was 4 days (interquartile range, 3-8 days). Corticosteroids were used in 33 (63%) patients. During corticosteroid treatment, superimposed infections were observed in 10 (30%) patients and surgical site complications were observed in 9 (27%). Overall in-hospital mortality was 10%.

Conclusions

The prevalence and mortality of ALI following esophagectomy in our study were lower than those of previous reports. However, the use of corticosteroids in patients with ALI following esophagectomy requires attention to the occurrence of surgical site complications and close surveillance to identify new infections.

Influence of bronchial diameter change on the airflow dynamics based on a pressure-controlled ventilation system

Bronchial diameter is a key parameter that affects the respiratory treatment of mechanically ventilated patients. In this paper, to reveal the influence of bronchial diameter on the airflow dynamics of pressure-controlled mechanically ventilated patients, a new respiratory system model is presented that combines multigeneration airways with lungs. Furthermore, experiments and simulation studies to verify the model are performed. Finally, through the simulation study, it can be determined that in airway generations 2 to 7, when the diameter is reduced to half of the original value, the maximum air pressure (maximum air pressure in lungs) decreases by nearly 16%, the maximum flow decreases by nearly 30%, and the total airway pressure loss (sum of each generation pressure drop) is more than 5 times the original value. Moreover, in airway generations 8 to 16, with increasing diameter, the maximum air pressure, maximum flow, and total airway pressure loss remain almost constant. When the diameter is reduced to half of the original value, the maximum air pressure decreases by 3%, the maximum flow decreases by nearly 5%, and the total airway pressure loss increases by 200%. The study creates a foundation for improvement in respiratory disease diagnosis and treatment.

Anesthesia and fast-track in video-assisted thoracic surgery (VATS): from evidence to practice

In thoracic surgery, the introduction of video-assisted thoracoscopic techniques has allowed the development of fast-track protocols, with shorter hospital lengths of stay and improved outcomes. The perioperative management needs to be optimized accordingly, with the goal of reducing postoperative complications and speeding recovery times. Premedication performed in the operative room should be wisely administered because often linked to late discharge from the post-anesthesia care unit (PACU). Inhalatory anesthesia, when possible, should be preferred based on protective effects on postoperative lung inflammation. Deep neuromuscular blockade should be pursued and carefully monitored, and an appropriate reversal administered before extubation. Management of one-lung ventilation (OLV) needs to be optimized to prevent not only intraoperative hypoxemia but also postoperative acute lung injury (ALI): protective ventilation strategies are therefore to be implemented. Locoregional techniques should be favored over intravenous analgesia: the thoracic epidural, the paravertebral block (PVB), the intercostal nerve block (ICNB), and the serratus anterior plane block (SAPB) are thoroughly reviewed and the most common dosages are reported. Fluid therapy needs to be administered critically, to avoid both overload and cardiovascular compromisation. All these practices are analyzed singularly with the aid of the most recent evidences aimed at the best patient care. Finally, a few notes on some of the latest trends in research are presented, such as non-intubated video-assisted thoracoscopic surgery (VATS) and intravenous lidocaine.

Effects of volume-controlled ventilation vs. pressure-controlled ventilation on respiratory function and inflammatory factors in patients undergoing video-assisted thoracoscopic radical resection of pulmonary carcinoma

Background

The best ventilation approach for patients undergoing video-assisted thoracic surgery (ATS) for pulmonary carcinoma remains undefined. This study aimed to assess hemodynamics, airway pressure, arterial blood gas, and inflammatory factors in patients undergoing VATS for pulmonary carcinoma under volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV).

Methods

This was a prospective study of 60 patients with pulmonary carcinoma treated at a tertiary center in 2015-2016. The subjects were randomized to the VCV or PCV group after anesthesia and total lung ventilation (TLV). Hemodynamics and blood gas parameters were compared between the two groups pre-OLV (one-lung ventilation) (T1) and after 30 (T2), 60 (T3), and 120 (T4) minutes of OLV. Radial artery blood was collected to measure interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α levels.

Results

Hemodynamic and blood gas parameters were similar between the two groups (all P>0.05). During OLV, airway resistance (RAW) was significantly lower in the PCV group compared with the VCV group at T2 (26.0±3.8 vs. 29.9±7.3 cmH₂O/L/s), T3 (26.0±3.7 vs. 30.2±7.7 cmH₂O/L/s), and T4 (25.8±4.1 vs. 29.6±6.7 cmH₂O/L/s). Similar trends were found for peak pressure (Ppeak) and plateau pressure (Pplat). Mean pressure (Pmean) was similar between the two groups. Compared with the PCV group, TNF-α and IL-6 levels in the VCV group were significantly increased (all P<0.05). The levels of the anti-inflammatory mediator IL-10 were higher in the PCV group compared with the VCV group.

Conclusions

PCV for OLV during radical resection of pulmonary carcinoma by VATS could reduce Ppeak and downregulate pro-inflammatory factors, likely decreasing airway injury.

Enhanced Recovery in Thoracic Surgery: A Review

The main goal of enhanced recovery program after thoracic surgery is to minimize stress response, reduce postoperative pulmonary complications, and improve patient outcome, which will in addition decrease hospital stay and reduce hospital costs. As minimally invasive technique, video-assisted thoracoscopic surgery represents an important element of enhanced recovery program in thoracic surgery. Anesthetic management during preoperative, intraoperative and postoperative period is essential for the enhanced recovery. In the era of enhanced recovery protocols, non-intubated thoracoscopic procedures present a step forward. This article focuses on the key elements of the enhanced recovery program in thoracic surgery. Having reviewed recent literature, the authors highlight potential procedures and techniques that might be incorporated into the program.

Comparison of pressure vs. volume controlled ventilation on oxygenation parameters of obese patients undergoing laparoscopic cholecystectomy

Background & Objective:

There is no special guideline for the best ventilation mode during laparoscopic anesthesia in obese patients and there are too many studies with different controversial points. The aim of this study was to compare the effect of pressure controlled ventilation (PCV) vs. volume controlled ventilation (VCV) on respiratory and oxygenation parameters in patients undergoing laparoscopic cholecystectomy.

Methods:

Seventy patients with 30 <BMI<40 and ASA physical status I-II were studied in this randomized prospective trial. Anesthesia was started with VCV and after creation of pneumoperitoneum; the patients were randomized into PCV or VCV groups. Ventilation parameters were adjusted to a CO2 target of 35-40 mmHg. Hemodynamic and oxygenation parameters and respiratory parameters like plateau, mean airway and peak pressure were recorded for all patients during the study.

Results:

Patients in VCV group needed higher tidal volume and respiratory rate to maintain target CO₂ in 35 and 55 minutes after the study. Plateau pressure and mean airway pressure in two groups didn’t have significant difference between two groups but peak airway pressure in 35 and 55 minutes after pneumoperitoneum was significantly higher in VCV group than PCV group. There were no significant differences between two groups regarding PO₂, PCO₂ and pH, except 35 and 55 minutes after pneumoperitoneum. In mentioned times, patients in PCV group had significantly higher PO₂ levels compared to VCV group.

Conclusion:

Despite some beneficial effects regarding plateau, mean airway pressure and oxygenation parameters with PCV, there was no significant clinical difference between PCV and VCV in obese patients undergoing laparoscopic cholecystectomy.

Comparison of volume control and pressure control ventilation in patients undergoing single level anterior cervical discectomy and fusion surgery

Background and Aims:

Pressure control and volume control ventilation are the most preferred modes of ventilator techniques available in the intraoperative period. The study compared the intraoperative ventilator and blood gas variables of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) in patients undergoing single level anterior cervical discectomy and fusion (ACDF).

Methods:

After obtaining Institutional Ethical Committee approval and informed consent, sixty patients scheduled for single level ACDF surgery performed in supine position under general anaesthesia were included. Group V (30 patients) received VCV and Group P (30 patients) received PCV. The primary objective was oxygenation variable PaO₂/FiO₂ at different points of time i.e. T1–20 min after the institution of the ventilation, T2–20 min after placement of the retractors and T3–20 min after removal of the retractors. The secondary objectives include other arterial blood gas parameters, respiratory and haemodynamic parameters. NCSS version 9 statistical software was used for statistics. Two-way repeated measures for analysis of variance with post hoc Tukey Kramer test was used to analyse continuous variables for both intra- and inter-group comparisons, paired sample t-test for overall comparison and Chi-square test for categorical data.

Results:

The primary variable PaO₂/FiO₂ was comparable in both groups (P = 0.08). The respiratory variables, PAP and C_dynam were statistically significant in PCV group compared to VCV (P < 0.05), though clinically insignificant. Other secondary variables were comparable. (P > 0.05)

Conclusion:

Clinically, both PCV and VCV group appear to be-equally suited ventilator techniques for anterior cervical spine surgery patients.

Effect of Switching between Pressure-controlled and Volume-controlled Ventilation on Respiratory Mechanics and Hemodynamics in Obese Patients during Abdominoplasty

Background:

The ideal intraoperative ventilation strategy in obese patients remains obscure. This prospective, randomized study was designed to evaluate the effect of pressure-controlled ventilation (PCV) before or after volume-controlled ventilation (VCV) on lung mechanics and hemodynamics variables in obese patients subjected to abdominoplasty operation.

Patients and Methods:

The study included forty patients with body mass index 30–45 kg/m² subjected to abdominoplasty. All patients were randomly allocated in two groups after the induction of general anesthesia (twenty patients each), according to intraoperative ventilatory strategy. Group I (P-V): started with PCV until the plication of rectus muscle changes into VCV till the end of surgery. Group II (V-P): started with VCV until the plication of rectus muscle changes into PCV till the end of surgery. Lung mechanics, hemodynamics variables (heart rate and mean blood pressure), and arterial blood gases (ABGs) were recorded.

Results:

No significant difference in the hemodynamics and ABGs were recorded between the studied groups. The use of PCV after VCV induced the improvement of lung mechanics.

Conclusion:

Switching from VCV to PCV is preferred to improve intraoperative oxygenation and lung compliance without adverse hemodynamic effects in obese patients.

Comparison of volume controlled ventilation and pressure controlled ventilation in patients undergoing robot-assisted pelvic surgeries: An open-label trial

Background and Aims:

Although volume controlled ventilation (VCV) has been the traditional mode of ventilation in robotic surgery, recently pressure controlled ventilation (PCV) has been used more frequently. However, evidence on whether PCV is superior to VCV is still lacking. We intended to compare the effects of VCV and PCV on respiratory mechanics and haemodynamic in patients undergoing robotic surgeries in steep Trendelenburg position.

Methods:

This prospective, randomized trial was conducted on sixty patients between 20 and 70 years belonging to the American Society of Anesthesiologist Physical Status I–II. Patients were randomly assigned to VCV group (n = 30), where VCV mode was maintained through anaesthesia, or the PCV group (n = 30), where ventilation mode was changed to PCV after the establishment of 40° Trendelenburg position and pneumoperitoneum. Respiratory (peak and mean airway pressure [AP_peak, AP_mean], dynamic lung compliance [C_dyn] and arterial blood gas analysis) and haemodynamics variables (heart rate, mean blood pressure [MBP] central venous pressure) were measured at baseline (T₁), post-Trendelenburg position at 60 min (T₂), 120 min (T₃) and after resuming supine position (T₄).

Results:

Demographic profile, haemodynamic variables, oxygen saturation and minute ventilation (MV) were comparable between two groups. Despite similar values of AP_mean, AP_peak was significantly higher in VCV group at T2 and T3 as compared to PCV group (P < 0.001). C_dyn and PaCO₂ were also better in PCV group than in VCV group (P < 0.001 and 0.045, respectively).

Conclusion:

PCV should be preferred in robotic pelvic surgeries as it offers lower airway pressures, greater C_dyn and a better-preserved ventilation-perfusion matching for the same levels of MV.

Anesthetic management of robot-assisted thoracoscopic thymectomy

Myasthenia gravis (MG) is a rare disorder involving neuromuscular junction. In conjunction with medical therapy, thymectomy is a known modality of treatment of MG and has shown to increase the probability of remission and overall symptomatic improvement. For minimally invasive thymectomy, video-.assisted thoracoscopic surgery has been the preferred surgical approach till recently. The robotic surgical procedure must necessarily bring new challenges to the anesthesiologists to effectively meet the specific requirements of the technique. At present, there is a paucity of literature regarding the anesthetic concerns of robotic assisted thymectomy, patient in question specifically posed a challenge since different maneuvers and techniques had to be tried to obtain optimum surgical conditions with stable ventilatory and hemodynamic parameters. Concerns of patient positioning and hemodynamic monitoring have also been discussed.

Comparison of pressure-controlled ventilation with volume-controlled ventilation during one-lung ventilation: a systematic review and meta-analysis

BACKGROUND

Not only arterial hypoxemia but acute lung injury also has become the major concerns of one-lung ventilation (OLV). The use of pressure-controlled ventilation (PCV) for OLV offers the potential advantages of lower airway pressure and intrapulmonary shunt, which result in a reduced risk of barotrauma and improved oxygenation, respectively.

METHODS

We searched Medline, Embase, the Cochrane central register of controlled trials and KoreaMedto find publications comparing the effects of PCV with those of volume-controlled ventilation (VCV) during intraoperative OLV in adults. A meta-analysis of randomized controlled trials was performed using the Cochrane Review Methods.

RESULTS

Six studies (259 participants) were included. The PaO2/FiO2 ratio in PCV was higher than in VCV [weighted mean difference (WMD) = 11.04 mmHg, 95 % confidence interval (CI) = 0.30 to 21.77, P = 0.04, I(2) = 3 %] and peak inspiratory pressure was significantly lower in PCV (WMD = -4.91 cm H2O, 95 % CI = -7.30 to -2.53, P < 0.0001, I (2) = 91 %). No differences in PaCO2, tidal volume, heart rate and blood pressure were observed. There were also no differences incompliance, plateau and mean airway pressure.

CONCLUSIONS

Our meta-analysis provided the evidence of improved oxygenation in PCV. However, it is difficult to draw any definitive conclusions due to the fact that the duration of ventilation in the studies reviewed was insufficient to reveal clinically relevant benefits or disadvantages of PCV. Significantly lower peak inspiratory pressure is the advantage of PCV.

Dynamic Characteristics of Mechanical Ventilation System of Double Lungs with Bi-Level Positive Airway Pressure Model

In recent studies on the dynamic characteristics of ventilation system, it was considered that human had only one lung, and the coupling effect of double lungs on the air flow can not be illustrated, which has been in regard to be vital to life support of patients. In this article, to illustrate coupling effect of double lungs on flow dynamics of mechanical ventilation system, a mathematical model of a mechanical ventilation system, which consists of double lungs and a bi-level positive airway pressure (BIPAP) controlled ventilator, was proposed. To verify the mathematical model, a prototype of BIPAP system with a double-lung simulators and a BIPAP ventilator was set up for experimental study. Lastly, the study on the influences of key parameters of BIPAP system on dynamic characteristics was carried out. The study can be referred to in the development of research on BIPAP ventilation treatment and real respiratory diagnostics.

One-Lung Anesthesia Update

One-lung ventilation is used during a variety of cardiac, thoracic, and major vascular procedures. Endobronchial tubes, bronchial blockers, and occasionally, single-lumen tubes are used to isolate the lungs. Patients with difficult airways and pediatric patients provide special challenges for lung isolation. Finally, intraoperative hypoxia and hypercarbia in patients with intrinsic lung disease frequently complicate one-lung anesthesia. The concepts and controversies in lung isolation techniques are discussed.

Common Pitfalls in Anesthesia for Noncardiac Thoracic Surgery

Over the past few decades, major surgical procedures involving the thorax have become commonplace at most larger medical facilities. Advances in perioperative care have allowed surgeons to perform increasingly complex procedures. These procedures are being performed on more seriously ill patients who are at increased risk for significant complications. Recent advances should help the anesthesiologist avoid some of the pitfalls in managing these complex patients. Preoperative assessment aids in the identification of patients at highest risk for intraoperative and postoperative events. Particular attention is given to myasthenia gravis, as thymectomy is among the most common surgical procedures that are performed in these patients. Aggressive pain control techniques, including neuraxial opioids and patient-controlled analgesia, where appropriate, not only improve patient comfort but can improve postoperative pulmonary function. Advances in techniques for providing one-lung ventilation allow the anesthesiologist more options to individualize management for each clinical scenario. Careful fluid management may help to minimize the risk of postoperative pulmonary complications. A basic understanding of video-assisted thoracic surgery should help the anesthesiologist provide optimal surgical conditions and perioperative care. Recent advances demand a greater role for the anesthesiologist if the best outcomes are to be achieved in patients undergoing thoracic procedures.

Intraoperative mechanical ventilation strategies in patients undergoing one-lung ventilation: a meta-analysis

BACKGROUND

Postoperative pulmonary complications (PPCs), which are not uncommon in one-lung ventilation, are among the main causes of postoperative death after lung surgery. Intra-operative ventilation strategies can influence the incidence of PPCs. High tidal volume (V T) and increased airway pressure may lead to lung injury, while pressure-controlled ventilation and lung-protective strategies with low V T may have protective effects against lung injury. In this meta-analysis, we aim to investigate the effects of different ventilation strategies, including pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), protective ventilation (PV) and conventional ventilation (CV), on PPCs in patients undergoing one-lung ventilation. We hypothesize that both PV with low V T and PCV have protective effects against PPCs in one-lung ventilation.

METHODS

A systematic search (PubMed, EMBASE, the Cochrane Library, and Ovid MEDLINE; in May 2015) was performed for randomized trials comparing PCV with VCV or comparing PV with CV in one-lung ventilation. Methodological quality was evaluated using the Cochrane tool for risk. The primary outcome was the incidence of PPCs. The secondary outcomes included the length of hospital stay, intraoperative plateau airway pressure (Pplateau), oxygen index (PaO2/FiO2) and mean arterial pressure (MAP).

RESULTS

In this meta-analysis, 11 studies (436 patients) comparing PCV with VCV and 11 studies (657 patients) comparing PV with CV were included. Compared to CV, PV decreased the incidence of PPCs (OR 0.29; 95 % CI 0.15-0.57; P < 0.01) and intraoperative Pplateau (MD -3.75; 95 % CI -5.74 to -1.76; P < 0.01) but had no significant influence on the length of hospital stay or MAP. Compared to VCV, PCV decreased intraoperative Pplateau (MD -1.46; 95 % CI -2.54 to -0.34; P = 0.01) but had no significant influence on PPCs, PaO2/FiO2 or MAP.

CONCLUSIONS

PV with low V T was associated with the reduced incidence of PPCs compared to CV. However, PCV and VCV had similar effects on the incidence of PPCs.

Effect of Mechanical Ventilation Mode Type on Intra- and Postoperative Blood Loss in Patients Undergoing Posterior Lumbar Interbody Fusion Surgery

Background

The aim of study was to evaluate the effect of mechanical ventilation mode type, pressure-controlled ventilation (PCV), or volume-controlled ventilation (VCV) on intra- and postoperative surgical bleeding in patients undergoing posterior lumbar interbody fusion (PLIF) surgery.

Methods

This was a prospective, randomized, single-blinded, and parallel study that included 56 patients undergoing PLIF and who were mechanically ventilated using PCV or VCV. A permuted block randomization was used with a computer-generated list. The hemodynamic and respiratory parameters were measured after anesthesia induction in supine position, 5 min after patients were changed from supine to prone position, at the time of skin closure, and 5 min after the patients were changed from prone to supine position. The amount of intraoperative surgical bleeding, fluid administration, urine output, and transfusion requirement were measured at the end of surgery. The amount of postoperative bleeding and transfusion requirement were recorded every 24 h for 72 h.

Results

The primary outcome was the amount of intraoperative surgical bleeding, and 56 patients were analyzed. The amount of intraoperative surgical bleeding was significantly less in the PCV group than that in the VCV group (median, 253.0 [interquartile range, 179.0 to 316.5] ml in PCV group vs. 382.5 [328.0 to 489.5] ml in VCV group; P &lt; 0.001). Comparing other parameters between groups, only peak inspiratory pressure at each measurement point in PCV group was significantly lower than that in VCV group. No harmful events were recorded.

Conclusion

Intraoperative PCV decreased intraoperative surgical bleeding in patients undergoing PLIF, which may be related to lower intraoperative peak inspiratory pressure.

Comparison of intraoperative volume and pressure-controlled ventilation modes in patients who undergo open heart surgery

Respiratory problems occur more frequently in patients who undergo open heart surgery. Intraoperative and postoperative ventilation strategies can prevent these complications and reduce mortality. We hypothesized that PCV would have better effects on gas exchange, lung mechanics and hemodynamics compared to VCV in CABG surgery. Our primary outcome was to compare the PaO₂/FiO₂ ratio. Patients were randomized into two groups, (VCV, PCV) consisting of 30 individuals each. Two patients were excluded from the study. I/E ratio was adjusted to 1:2 and, RR:10/min fresh air gas flow was set at 3L/min in all patients. In the VCV group TV was set at 8 mL/kg of the predicted body weight. In the PCV group, peak inspiratory pressure was adjusted to the same tidal volume with the VCV group. PaO2/FiO2 was found to be higher with PCV at the end of the surgery. Time to extubation and ICU length of stay was shorter with PCV. Ppeak was similar in both groups. Pplateau was lower and Pmean was higher at the and of the surgery with PCV compared to VCV. The hemodynamic effects of both ventilation modes were found to be similar. PVC may be preferable to VCV in patients who undergo open heart surgery. However, it would be convenient if our findings are supported by similar studies.

Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in patients with low diffusion capacity of lung for carbon monoxide: a crossover study

STUDY OBJECTIVE

To investigate the effects of a 1:1 inspiratory-to-expiratory (I:E) ventilation ratio on oxygenation and respiratory mechanics during one-lung ventilation (OLV) in patients with low diffusion capacity of lung for carbon monoxide (DLCO).

DESIGN

Prospective, randomized, crossover study.

SETTING

Operating room, university hospital.

PATIENTS

Twenty-six patients with a preoperative DLCO less than 80% who were scheduled for lung lobectomy requiring OLV under general anesthesia.

INTERVENTIONS

In the first group (n = 13), OLV was begun with a 1:1 I:E ratio, which was switched to a 1:2 I:E ratio after 30 minutes. In the second group (n = 13), the modes of ventilation were performed in the opposite order. Pressure-controlled ventilation with 5 cm H2O of positive end-expiratory pressure and a tidal volume of 5 to 8 mL/kg was applied during OLV.

MEASUREMENTS

Arterial and central venous blood gas analyses were recorded and used to calculate intrapulmonary shunt fraction and physiologic dead space. These measurements were taken at 4 time points: 10 minutes after two-lung ventilation in the lateral decubitus position, 30 minutes after initiation of OLV, 30 minutes after switching the I:E ratio, and 10 minutes after two-lung ventilation was resumed.

MAIN RESULTS

There was no difference in arterial oxygen tension during OLV between the 2 groups (P = .429). Arterial carbon dioxide tension and peak airway pressure were lower in the 1:1 group than in the 1:2 group (P = .003; P = .008). Physiologic dead space was also decreased in the 1:1 I:E ratio group (P = .003). Mean airway pressure and dynamic compliance were higher in the 1:1 group (P = .003; P = .007).

CONCLUSIONS

Pressure-controlled ventilation with a 1:1 I:E ventilation ratio did not improve oxygenation in patients with low DLCO during OLV compared with a 1:2 I:E ventilation ratio. However, it did provide benefits in terms of respiratory mechanics and increased the efficiency of alveolar ventilation during OLV.

Differential Effects of Endotracheal Suctioning on Gas Exchanges in Patients with Acute Respiratory Failure under Pressure-Controlled and Volume-Controlled Ventilation

This study was conducted to evaluate the effects of open endotracheal suctioning on gas exchange and respiratory mechanics in ARF patients under the modes of PCV or VCV. Ninety-six ARF patients were treated with open endotracheal suctioning and their variations in respiratory mechanics and gas exchange after the suctions were compared. Under PCV mode, compared with the initial level of tidal volume (V_T), ARF patients showed 30.0% and 27.8% decrease at 1 min and 10 min, respectively. Furthermore, the initial respiratory system compliance (C_rs) decreased by 29.6% and 28.5% at 1 min and 10 min, respectively. Under VCV mode, compared with the initial level, 38.6% and 37.5% increase in peak airway pressure (PAP) were found at 1 min and 10 min, respectively. Under PCV mode, the initial PaO₂ increased by 6.4% and 10.2 % at 3 min and 10 min, respectively, while 18.9% and 30.6% increase of the initial PaO₂ were observed under VCV mode. Summarily, endotracheal suctioning may impair gas exchange and decrease lung compliance in ARF patients receiving mechanical ventilation under both PCV and VCV modes, but endotracheal suctioning effects on gas exchange were more severe and longer-lasting under PCV mode than VCV.

Anesthesia for esophagectomy

Esophagectomy is a high-risk operation with significant perioperative morbidity and mortality. Attention to detail in many areas of perioperative management should lead to an aggregation of marginal gains and improvement in postoperative outcome. This review addresses preoperative assessment and patient selection, perioperative care (focusing on pulmonary prehabilitation, ventilation strategies, goal-directed fluid therapy, analgesia, and cardiovascular complications), minimally invasive surgery, and current evidence for enhanced recovery in esophagectomy.

Pressure-controlled versus volume-controlled ventilation for acute respiratory failure due to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) account for one-quarter of cases of acute respiratory failure in intensive care units (ICUs). A third to half of patients will die in the ICU, in hospital or during follow-up. Mechanical ventilation of people with ALI/ARDS allows time for the lungs to heal, but ventilation is invasive and can result in lung injury. It is uncertain whether ventilator-related injury would be reduced if pressure delivered by the ventilator with each breath is controlled, or whether the volume of air delivered by each breath is limited.

OBJECTIVES

To compare pressure-controlled ventilation (PCV) versus volume-controlled ventilation (VCV) in adults with ALI/ARDS to determine whether PCV reduces in-hospital mortality and morbidity in intubated and ventilated adults.

SEARCH METHODS

In October 2014, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Isssue 9), MEDLINE (1950 to 1 October 2014), EMBASE (1980 to 1 October 2014), the Latin American Caribbean Health Sciences Literature (LILACS) (1994 to 1 October 2014) and Science Citation Index-Expanded (SCI-EXPANDED) at the Institute for Scientific Information (ISI) Web of Science (1990 to 1 October 2014), as well as regional databases, clinical trials registries, conference proceedings and reference lists.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs (irrespective of language or publication status) of adults with a diagnosis of acute respiratory failure or acute on chronic respiratory failure and fulfilling the criteria for ALI/ARDS as defined by the American-European Consensus Conference who were admitted to an ICU for invasive mechanical ventilation, comparing pressure-controlled or pressure-controlled inverse-ratio ventilation, or an equivalent pressure-controlled mode (PCV), versus volume-controlled ventilation, or an equivalent volume-controlled mode (VCV).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected trials, assessed risk of bias and extracted data. We sought clarification from trial authors when needed. We pooled risk ratios (RRs) for dichotomous data and mean differences (MDs) for continuous data with their 95% confidence intervals (CIs) using a random-effects model. We assessed overall evidence quality using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

We included three RCTs that randomly assigned a total of 1089 participants recruited from 43 ICUs in Australia, Canada, Saudi Arabia, Spain and the USA. Risk of bias of the included studies was low. Only data for mortality and barotrauma could be combined in the meta-analysis. We downgraded the quality of evidence for the three mortality outcomes on the basis of serious imprecision around the effect estimates. For mortality in hospital, the RR with PCV compared with VCV was 0.83 (95% CI 0.67 to 1.02; three trials, 1089 participants; moderate-quality evidence), and for mortality in the ICU, the RR with PCV compared with VCV was 0.84 (95% CI 0.71 to 0.99; two trials, 1062 participants; moderate-quality evidence). One study provided no evidence of clear benefit with the ventilatory mode for mortality at 28 days (RR 0.88, 95% CI 0.73 to 1.06; 983 participants; moderate-quality evidence). The difference in effect on barotrauma between PCV and VCV was uncertain as the result of imprecision and different co-interventions used in the studies (RR 1.24, 95% CI 0.87 to 1.77; two trials, 1062 participants; low-quality evidence). Data from one trial with 983 participants for the mean duration of ventilation, and from another trial with 78 participants for the mean number of extrapulmonary organ failures that developed with PCV or VCV, were skewed. None of the trials reported on infection during ventilation or quality of life after discharge.

AUTHORS' CONCLUSIONS

Currently available data from RCTs are insufficient to confirm or refute whether pressure-controlled or volume-controlled ventilation offers any advantage for people with acute respiratory failure due to acute lung injury or acute respiratory distress syndrome. More studies including a larger number of people given PCV and VCV may provide reliable evidence on which more firm conclusions can be based.

Step-by-step clinical management of one-lung ventilation: continuing professional development

PURPOSE

The purpose of this Continuing Professional Development Module is to review the issues pertinent to one-lung ventilation (OLV) and to propose a management strategy for ventilation before, during, and after lung isolation.

PRINCIPAL FINDINGS

The need for optimal lung isolation has increased with the advent of video-assisted thoracoscopic surgery, as surgical exposure is critical for successful surgery. Continuous positive airway pressure applied to the operative lung or intermittent two-lung ventilation should therefore be avoided if possible. Optimal management of OLV should provide adequate oxygenation and also prevent acute lung injury (ALI), the leading cause of death following lung resection. Research conducted in the last decade suggests implementing a protective ventilation strategy during OLV that consists of small tidal volumes based on ideal body weight, routine use of positive end-expiratory pressure, low inspired oxygen fraction, with low peak and plateau airway pressures. High respiratory rates to compensate for low tidal volumes may predispose to significant air trapping during OLV, so permissive hypercapnea is routinely employed. The management of OLV extends into the period of two-lung ventilation, as the period prior to OLV impacts lung collapse, and both the time before and after OLV influence the extent of ALI. Lung re-expansion at the conclusion of OLV is an important component of ensuring adequate ventilation and oxygenation postoperatively but may be harmful to the lung.

CONCLUSIONS

Optimal perioperative care of the thoracic patient includes a protective ventilation strategy from intubation to extubation and into the immediate postoperative period. Anesthetic goals include the prevention of perioperative hypoxemia and postoperative ALI.

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

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 (P_peak), 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.

Pressure-controlled versus volume-controlled ventilation during one-lung ventilation in elderly patients with poor pulmonary function

OBJECTIVE:

The aim was to investigate the effects of two different ventilatory strategies: Pressure-controlled ventilation (PCV) versus volume-controlled ventilation (VCV) in elderly patients with poor pulmonary function during one-lung ventilation (OLV).

PATIENTS AND METHODS:

The patients were enrolled into the study having poor pulmonary function (forced expiratory volume in 1 s <1.5 L) and undergoing radical resection of pulmonary carcinoma requiring at least 2 h of OLV. Patients were respectively allocated to VCV group and PCV group. The intraoperative data, arterial, and mixed venous blood gases were obtained at baseline, 20, 40, 60, 80, 100 and 120 min after OLV and end of surgery. The postoperative data had been recorded and arterial gas measurements were performed at 6, 12 and 24 h after surgery in Intensive Care Unit.

RESULTS:

Comparison of the VCV group and PCV group, PaO₂ and P(A-a)O₂ were higher and dead space to tidal volume was lower in the PCV group (P < 0.05) after the point of OLV +60, Ppeak was higher in the VCV group (P < 0.05). There were significant advantages in PCV groups with regard to the PaO₂ of three points in postoperation, the duration of postoperative ventilation duration, intensive care duration of stay and the days stay in hospital after surgery.

CONCLUSIONS:

The use of PCV compared with VCV during OLV in elderly patients with poor pulmonary function has significant advantages of intraoperative and postoperative oxygenation and it might be a factor, which can beneficial to postoperative recovery.

Pressure dynamic characteristics of pressure controlled ventilation system of a lung simulator

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.