Thoracic anaesthetic research: 90 years of sustained progress.

Over the 90 years since the first description of one-lung ventilation, the practice of thoracic surgery and anaesthesia continues to develop. Minimally invasive surgical techniques are increasingly being used to minimise the surgical insult and facilitate improved outcomes. Challenging these outcomes, however, are parallel changes in patient characteristics with more older and sicker patients undergoing surgery. Thoracic anaesthesia as a speciality continues to respond to these challenges with evolution of practice and strong academic performance.

A Clinical Comparison of 2 Bronchial Blockers Versus Double-Lumen Tubes for One-Lung Ventilation.

OBJECTIVES: To compare the quality of lung collapse, time, and number of attempts required to achieve lung isolation, and incidence of intraoperative malpositioning between the EZ blocker (EZB), Fuji Uniblocker (UB), and the left-sided double lumen tube (DLT). DESIGN: Prospective, randomized clinical trial. SETTING: Single tertiary-level, university-affiliated hospital. PARTICIPANTS: Eighty-nine patients undergoing elective open thoracotomies or video-assisted thoracoscopic surgery. INTERVENTIONS: The 89 patients were randomized to receive a DLT, UB, or EZB for one-lung ventilation. MEASUREMENTS AND MAIN RESULTS: The quality of lung collapse at the time of pleural opening and 10 and 20 minutes thereafter were assessed by the surgeon using the Lung Collapse Score (LCS; 0 = no lung collapse to 10 = best lung collapse). The time and number of attempts required to achieve lung isolation and the number of repositions required during surgery were measured. Tracheobronchial tree measurements were performed by radiologists from preoperative computed tomography imaging. The surgeon remained blinded to the type of device used. Twenty-nine patients were randomized to the DLT group and 30 patients to each of the EZB and UB groups. The LCSs among the groups at pleural opening and 10 minutes after pleural opening were not significantly different (p = 0.34 and p = 0.08, respectively). However, at 20 minutes after the pleural opening, the LCSs were significantly different among groups (p = 0.02), with median scores being significantly lower for DLT (9 [IQR 8-9]) than for EZB (9 [IQR 9-10]; p = 0.04) and UB (9.5 [IQR 9-10]; p = 0.02). Lung isolation was achieved fastest in the DLT group (p < 0.01). The frequency of difficult placement did not significantly differ among groups, although it occurred most frequently in UB (n = 7; 23.3%). Intraoperative repositioning also occurred most often with the UB (n = 15; 50.0%). The EZB had the greatest number of cases requiring >2 repositions (n = 4, 13.3%). There were no differences between preoperative airway measurements and time to isolation or incidence of intraoperative repositioning among the groups. CONCLUSIONS: The LCS was comparable among the 3 devices until 20 minutes after pleural opening, when better scores were obtained in the bronchial blocker groups. Lung isolation was achieved fastest with the DLT. The EZB had the highest incidence of cases requiring >2 intraoperative repositions, mostly occurring in R-sided surgery. For L-sided surgery, the EZB performed equally to the UB. This suggests that using the EZB for R-sided video-assisted thoracoscopic surgery may be suboptimal. Preoperative airway dimensions did not correlate with time to achieve isolation or incidence of intraoperative malpositioning.

"Fit for Surgery? What's New in Preoperative Assessment of the High-Risk Patient Undergoing Pulmonary Resection".

Advances in perioperative assessment and diagnostics, together with developments in anesthetic and surgical techniques, have considerably expanded the pool of patients who may be suitable for pulmonary resection. Thoracic surgical patients frequently are perceived to be at high perioperative risk due to advanced age, level of comorbidity, and the risks associated with pulmonary resection, which predispose them to a significantly increased risk of perioperative complications, increased healthcare resource use, and costs. The definition of what is considered "fit for surgery" in thoracic surgery continually is being challenged. However, no internationally standardized definition of prohibitive risk exists. Perioperative assessment traditionally concentrates on the "three-legged stool" of pulmonary mechanical function, parenchymal function, and cardiopulmonary reserve. However, no single criterion should exclude a patient from surgery, and there are other perioperative factors in addition to the tripartite assessment that need to be considered in order to more accurately assess functional capacity and predict individual perioperative risk. In this review, the authors aim to address some of the more erudite concepts that are important in preoperative risk assessment of the patient at potentially prohibitive risk undergoing pulmonary resection for malignancy.

Intraoperative and Early Postoperative Management of Heart Transplantation: Anesthetic Implications.

The gold standard treatment for end-stage heart failure, with 50% mortality within 5 years of diagnosis, is considered heart transplantation. Despite the improvements in immunosuppression, the period of highest mortality risk in the heart transplantation population is during the first year post-transplantation, with primary graft dysfunction being the leading cause of mortality. After adequate preoperative assessment of the recipient, including patients on mechanical support, the intraoperative care of heart transplantation patients requires extensive monitoring followed by proficient management of anesthesia induction and maintenance, ventilation, and fluid therapy. The focus on weaning from cardiopulmonary bypass should be on preventing right ventricular failure and high pulmonary vascular resistances, with protocolized blood conservation strategies and transfusion protocols. The early postoperative care of a heart transplantation patient is focused on the post-cardiopulmonary bypass and transplantation status, with particular attention to the presence of primary graft dysfunction, right ventricular performance, pulmonary pressures, and vasoplegia. The aim is early extubation, inotropic and chronotropic support weaning, and chest tube removal to facilitate discharge of the patient from the intensive care unit. The increased complexity of heart transplantation recipients, including the incremental use of pre- transplantation mechanical circulatory support and extended criteria donor hearts, requires extensive and sophisticated preparation of the cardiac anesthesiologist. This article aims to provide an overview of the intraoperative and early postoperative anesthesia management of heart transplantation patients.

The Evolving Role of Extracorporeal Membrane Oxygenation in Lung Transplantation: Implications for Anesthetic Management.

Lung transplantation has become an accepted therapy for most causes of end-stage lung disease. Between 30 to 50% of lung transplants require extracorporeal life support (ECLS). In many lung transplantation centers, extracorporeal membrane oxygenation (ECMO) is replacing cardiopulmonary bypass (CPB) as the primary choice for intraoperative ECLS. This review will discuss the evolving role of ECMO in lung transplantation and its implications for anesthetic management.

Survey of Postoperative Regional Analgesia for Thoracoscopic Surgeries in Canada.

OBJECTIVES: To determine the preferences and perceptions regarding analgesic options for video-assisted thoracic surgery (VATS) among thoracic anesthesiologists in Canada. DESIGN: A cross-sectional survey of thoracic anesthesiologists with 30 multiple choice questions was e-mailed through an online survey tool called FluidSurveys was performed to members of the Canadian Anesthesiologists' Society. SETTING: A nationwide survey. PARTICIPANTS: Members of Canadian Anesthesiologists' Society who provide thoracic anesthesia INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Participant characteristics and outcomes are described using counts and percentages. The frequency of use of each technique for each surgical category is described in percentages and 95% confidence intervals. Based on the responses obtained from individual centers, approximately 469 anesthesiologists provided thoracic care in Canada at the time of the survey. The response rate to the survey was 19% (n = 89). Epidural analgesia was preferred by 93.42% (95% CI 85-98) for open surgeries compared with 41% (30-52) for VATS lobectomies. The difference was statistically significant-52% (37-67). Patient-controlled analgesia was preferred by 27% (19-39) for VATS lobectomies and 46% (35-57) for VATS minor resections. Only 14% preferred paravertebral block for any VATS surgeries. CONCLUSIONS: The use of analgesic techniques for VATS surgeries is variable and largely dictated by provider preferences. The majority still prefer epidural analgesia compared with paravertebral catheter (placed either by the anesthesiologist or surgeon). A broadly acceptable choice that is effective, safe, and technically less demanding requires comparative effectiveness studies and more uniform training for physicians.

Intraoperative Anesthetic Management of Lung Transplantation: Center-Specific Practices and Geographic and Centers Size Differences.

OBJECTIVE: Although increasing evidence in lung transplantation (LTx) suggests that intraoperative management could influence outcomes, there are no guidelines available regarding intraoperative management of LTx. The overall goal of the study was to assess geographic and center volume-specific clinical practices in perioperative management. DESIGN: Prospective data analysis. SETTING: Online survey from a single-center university hospital. PARTICIPANTS: European and non-European LTx centers. INTERVENTIONS: An online survey was sent to 176 centers currently performing LTx procedures. It covered organizational data, general anesthesia considerations, fluid therapy and coagulation, antioxidant and anti-inflammatory therapies, and ventilation strategies. MEASUREMENTS AND MAIN RESULTS: The response rates were 57.5% (n = 42) from European and 32% (n = 33) from non-European countries. Significant differences between European and non-European countries were use of volatile hypnotics (p = 0.016), use of sufentanil (p < 0.001), inotropic agents (p = 0.001) and colloid infusion (p < 0.001), use of calibrated pulse contour analysis (p = 0.004), use of intraoperative traditional laboratory-based coagulation tests (p = 0.001) and platelet function analysis (p = 0.005), and use of higher peak inspiratory pressure (p = 0.009). Center volume-specific differences were use of fentanyl (p = 0.03) and the use of higher peak inspiratory pressure (p = 0.005) for ventilation. Induction of anesthesia and use of advanced hemodynamic monitoring, therapy for pulmonary hypertension, antioxidant and anti-inflammatory therapies, and ventilation strategies were not different among the centers. CONCLUSIONS: This survey demonstrated for the first time statistically significant differences among European and non-European centers and among low- versus high-volume centers regarding intraoperative management during LTx. These observations will be of some guidance for the LTx community and may trigger more extensive studies.

Hypoxic pulmonary vasoconstriction: physiology and anesthetic implications.

Hypoxic pulmonary vasoconstriction (HPV) represents a fundamental difference between the pulmonary and systemic circulations. HPV is active in utero, reducing pulmonary blood flow, and in adults helps to match regional ventilation and perfusion although it has little effect in healthy lungs. Many factors affect HPV including pH or PCO2, cardiac output, and several drugs, including antihypertensives. In patients with lung pathology and any patient having one-lung ventilation, HPV contributes to maintaining oxygenation, so anesthesiologists should be aware of the effects of anesthesia on this protective reflex. Intravenous anesthetic drugs have little effect on HPV, but it is attenuated by inhaled anesthetics, although less so with newer agents. The reflex is biphasic, and once the second phase becomes active after about an hour of hypoxia, this pulmonary vasoconstriction takes hours to reverse when normoxia returns. This has significant clinical implications for repeated periods of one-lung ventilation.

Lung Injury After One-Lung Ventilation: A Review of the Pathophysiologic Mechanisms Affecting the Ventilated and the Collapsed Lung.

Lung injury is the leading cause of death after thoracic surgery. Initially recognized after pneumonectomy, it has since been described after any period of 1-lung ventilation (OLV), even in the absence of lung resection. Overhydration and high tidal volumes were thought to be responsible at various points; however, it is now recognized that the pathophysiology is more complex and multifactorial. All causative mechanisms known to trigger ventilator-induced lung injury have been described in the OLV setting. The ventilated lung is exposed to high strain secondary to large, nonphysiologic tidal volumes and loss of the normal functional residual capacity. In addition, the ventilated lung experiences oxidative stress, as well as capillary shear stress because of hyperperfusion. Surgical manipulation and/or resection of the collapsed lung may induce lung injury. Re-expansion of the collapsed lung at the conclusion of OLV invariably induces duration-dependent, ischemia-reperfusion injury. Inflammatory cytokines are released in response to localized injury and may promote local and contralateral lung injury. Protective ventilation and volatile anesthesia lessen the degree of injury; however, increases in biochemical and histologic markers of lung injury appear unavoidable. The endothelial glycocalyx may represent a common pathway for lung injury creation during OLV, because it is damaged by most of the recognized lung injurious mechanisms. Experimental therapies to stabilize the endothelial glycocalyx may afford the ability to reduce lung injury in the future. In the interim, protective ventilation with tidal volumes of 4 to 5 mL/kg predicted body weight, positive end-expiratory pressure of 5 to 10 cm H2O, and routine lung recruitment should be used during OLV in an attempt to minimize harmful lung stress and strain. Additional strategies to reduce lung injury include routine volatile anesthesia and efforts to minimize OLV duration and hyperoxia.

A simulator study of tube exchange with three different designs of double-lumen tubes.

BACKGROUND: We sought to determine whether the design of 3 different double-lumen endobronchial tubes (DLT) (Rusch, Mallinckrodt, Fuji) has an effect on the ease of placement over an airway exchange catheter (AEC) using a video laryngoscope. METHODS: A convenience sample of 17 anesthesia residents and fellows with at least 3 years of anesthesia training was recruited from teaching hospitals in Toronto for a randomized crossover trial. Each participant passed each DLT over an AEC in an airway simulator, visualized and video recorded via a video laryngoscope (GlideScope). The order of exchange was randomized by blindly pulling the name of the manufacturer of a DLT from a box. The primary outcome was time to intubate, defined as time from the bronchial lumen entering the GlideScope view to the bronchial lumen passing the vocal cords. Also recorded were participants' subjective rating of the ease of use and failure rate, defined as an attempt >150-second duration. RESULTS: Time to intubate was faster with the Fuji-Phycon DLT (median 2 seconds) compared with both the Rusch (median 27 seconds, P = 0.0144) and Mallinckrodt (median 21 seconds, P = 0.0117). On a scale of 1 to 10, with 10 being very easy to use and 1 being very difficult, the Fuji-Phycon was judged to be easier to use (median 10 seconds) compared with the Rusch (median 3, P = 0.0186) and the Mallinckrodt (median 4 seconds, P = 0.0123). The Rusch was associated with significantly more failures than the other DLTs, P = 0.002. CONCLUSIONS: The Fuji-Phycon DLT was easier to pass over an AEC in this simulator trial and warrants consideration in patients with difficult airways who require 1-lung ventilation.

From the Journal archives: Postoperative analgesia: effect on lung volumes.

This study was undertaken to determine the contribution of postoperative pain to the known changes that occur to respiratory function in the postoperative period. The authors studied changes in functional residual capacity (FRC) and vital capacity (VC) either in the postanesthesia care unit or on postoperative day one in eight relatively healthy adult patients having upper abdominal surgery. These values were compared with measurements immediately before surgery. Variables were measured postoperatively during pain and then again after establishment of epidural analgesia. Epidural analgesia to a T4 sensory level resulted in a partial and statistically significant restoration of VC (from 37-55% of preoperative values) and a partial but statistically insignificant restoration of FRC (from 78-84% of preoperative values). The authors suggest that postoperative epidural analgesia may be able to decrease respiratory complications. AUTHORS: Wahba MW, Don HF, Craig DB. Can Anaesth Soc J 1975; 22: 519-27. PURPOSE: This study was undertaken to determine the contribution of postoperative pain to the known changes that occur to respiratory function in the postoperative period. PRINCIPAL FINDINGS: Epidural analgesia to T4 resulted in a partial and statistically significant restoration of VC (from 37-55% of preoperative values) and a partial but statistically insignificant restoration of FRC (from 78-84% of preoperative values). CONCLUSION: Epidural analgesia has more effect on the voluntary aspects of postoperative respiration (VC) than on the involuntary changes in respiration (FRC) after upper abdominal surgery.