Protective versus Conventional Ventilation for Surgery: A Systematic Review and Individual Patient Data Meta-analysis.

BACKGROUND: Recent studies show that intraoperative mechanical ventilation using low tidal volumes (VT) can prevent postoperative pulmonary complications (PPCs). The aim of this individual patient data meta-analysis is to evaluate the individual associations between VT size and positive end-expiratory pressure (PEEP) level and occurrence of PPC. METHODS: Randomized controlled trials comparing protective ventilation (low VT with or without high levels of PEEP) and conventional ventilation (high VT with low PEEP) in patients undergoing general surgery. The primary outcome was development of PPC. Predefined prognostic factors were tested using multivariate logistic regression. RESULTS: Fifteen randomized controlled trials were included (2,127 patients). There were 97 cases of PPC in 1,118 patients (8.7%) assigned to protective ventilation and 148 cases in 1,009 patients (14.7%) assigned to conventional ventilation (adjusted relative risk, 0.64; 95% CI, 0.46 to 0.88; P < 0.01). There were 85 cases of PPC in 957 patients (8.9%) assigned to ventilation with low VT and high PEEP levels and 63 cases in 525 patients (12%) assigned to ventilation with low VT and low PEEP levels (adjusted relative risk, 0.93; 95% CI, 0.64 to 1.37; P = 0.72). A dose-response relationship was found between the appearance of PPC and VT size (R2 = 0.39) but not between the appearance of PPC and PEEP level (R2 = 0.08). CONCLUSIONS: These data support the beneficial effects of ventilation with use of low VT in patients undergoing surgery. Further trials are necessary to define the role of intraoperative higher PEEP to prevent PPC during nonopen abdominal surgery.

Quantitative Assessment of Right Ventricular Volumes and Ejection Fraction in Patients with Left Ventricular Systolic Dysfunction by Real Time Three-Dimensional Echocardiography versus Cardiac Magnetic Resonance Imaging.

AIMS: The aim of this study was to assess the accuracy and reproducibility of real time three-dimensional echocardiographic (RT3DE) for the determination of right ventricular (RV) volumes and function in patients with left ventricular (LV) systolic dysfunction. METHODS AND RESULTS: Dedicated RT3DE was prospectively performed to assess RV volumes and EF in patients with LV systolic function identified on routine clinical cardiac magnetic resonance (CMR) imaging. RV end-diastolic volume (RV EDV), RV end-systolic volume (RV ESV), and RV EF were obtained using an offline analysis software (TomTec) by two observers blinded to CMR results. In this population of 27 patients with LV systolic dysfunction with a mean LV EF of 36 ± 12%, RV RT3DE dataset could be assessed in 27 of 30 patients (90%). High correlation was noted between RT3DE and CMR for RV EDV, ESV, and EF (r = 0.90, 0.89, and 0.77, respectively). RV EDV was lower by RT3DE as compared to CMR (129 ± 52 vs. 142 ± 53 mL, P = 0.005) while there was no significant difference in RV ESV and RV EF (71 ± 37 vs. 77 ± 45 mL, P = 0.146; 45 ± 11 vs. 48 ± 13%, P = 0.134, respectively). The intraclass correlation coefficient ranged from 0.94 to 0.94 between measurements and from 0.84 to 0.96 between observers. CONCLUSION: Overall, RV volumes and EF assessed by RT3DE correlate well with CMR measurements in patients with LV dysfunction. RT3DE may be used as a more widely available and versatile alternative to CMR for the quantitative assessment of RV size and function in patients with LV dysfunction.

Perioperative renal outcome in cardiac surgical patients with preoperative renal dysfunction: aprotinin versus epsilon aminocaproic acid.

OBJECTIVE: The administration of aprotinin to patients with pre-existing renal dysfunction who are undergoing cardiac surgery is controversial. Therefore, the authors present their experience with the use of aprotinin for patients with preoperative renal dysfunction who underwent elective cardiac surgery requiring cardiopulmonary bypass (CPB). DESIGN: Retrospective analysis. SETTING: University hospital. PARTICIPANTS: Consecutive cardiac surgical patients with preoperative serum creatinine (SCr) > or =1.8 mg/dL undergoing nonemergent cardiac surgery requiring CPB. INTERVENTIONS: None. METHODS: One hundred twenty-three patients either received epsilon aminocaproic acid (EACA, n = 82) or aprotinin (n = 41) as decided by the attending anesthesiologist and surgeon. Data were collected from the Society of Thoracic Surgeons database and from automated intraoperative anesthesia records. Renal function was assessed from measured serum creatinine (SCr) and calculated creatinine clearances (CrCls). Acute perioperative renal dysfunction was defined as a worsening of perioperative renal function by > or =25% and/or the need for hemodialysis (HD). ANALYSIS: Data were recorded as mean and standard deviation or percentage of population depending on whether the data were continuous or not. Data were compared by using an analysis of variance, chi-square analysis, Student paired and unpaired t tests, Fisher exact test, Wilcoxon rank sum test, and Mann-Whitney U test. A p value <0.05 was considered significant. RESULTS: Overall, 32% and 41% of patients had acute perioperative renal dysfunction measured by CrCl and SCr, respectively. Seven patients required HD (5.7%). Six of these 7 had complicated postoperative courses. Of all the variables measured, only the duration of the aortic crossclamp (AoXCl) and CPB were significantly associated with acute perioperative renal dysfunction. Acute perioperative renal dysfunction was associated with increased intensive care unit and hospital stays, postoperative blood transfusion, dialysis, and major infection. Aprotinin patients were significantly older (75.2 v 70.2 years, p < 0.05), had lower left ventricular ejection fraction (44.4% v 49.2%, p < 0.05), a greater preoperative history of congestive heart failure (63 v 44%, p < 0.05), a greater renal risk score (5.8 v 4.9, p < 0.05), and underwent more nonisolated coronary artery bypass graft surgeries (77% v 29%, p < 0.0001). CPB time (126.0 v 96.5 minutes, p < 0.001) and AoXCl duration (100.9 v 78.0 minutes, p < 0.005) were longer in the aprotinin group. Diabetes (60.5% v 41.5%, p < 0.05) and hypertension (90.1% v 73.2%, p < 0.05) were more prevalent in the EACA group. Baseline renal function and renal outcomes were not significantly different between the aprotinin and EACA groups. Six of the 7 patients who required HD received EACA (p = 0.1). The earliest SCr recorded > or =3 months after surgery was significantly lower in the aprotinin group compared with the EACA group (1.8 v 2.2 mg/dL, p < 0.05). CONCLUSION: Acute perioperative renal dysfunction was associated with worse patient outcome and longer CPB and AoXCl times. Demographic and surgical variables indicated that the sicker patients undergoing more complex surgeries were more likely to be treated with aprotinin. Although aprotinin patients had a higher renal risk score, the administration of aprotinin did not negatively impact renal outcome.

Intraoperative application of geometric three-dimensional mitral valve assessment package: a feasibility study.

OBJECTIVE: To study the feasibility of using 3-dimensional (3D) echocardiography in the operating room for mitral valve repair or replacement surgery. To perform geometric analysis of the mitral valve before and after repair. DESIGN: Prospective observational study. SETTING: Academic, tertiary care hospital. PARTICIPANTS: Consecutive patients scheduled for mitral valve surgery. INTERVENTIONS: Intraoperative reconstruction of 3D images of the mitral valve. RESULTS: One hundred and two patients had 3D analysis of their mitral valve. Successful image reconstruction was performed in 93 patients-8 patients had arrhythmias or a dilated mitral valve annulus resulting in significant artifacts. Time from acquisition to reconstruction and analysis was less than 5 minutes. Surgeon identification of mitral valve anatomy was 100% accurate. CONCLUSIONS: The study confirms the feasibility of performing intraoperative 3D reconstruction of the mitral valve. This data can be used for confirmation and communication of 2-dimensional data to the surgeons by obtaining a surgical view of the mitral valve. The incorporation of color-flow Doppler into these 3D images helps in identification of the commissural or perivalvular location of regurgitant orifice. With improvements in the processing power of the current generation of echocardiography equipment, it is possible to quickly acquire, reconstruct, and manipulate images to help with timely diagnosis and surgical planning.

Primary mitral valve regurgitation: Update and review.

Mitral regurgitation is the second most common valvular disorder requiring surgical intervention worldwide. This review summarizes the current understanding of primary, degenerative mitral regurgitation with respect to etiology, comprehensive assessment, natural history and management. The new concept of staging of the valvular disorders, newer predictors of adverse and controversy of "watchful waiting" versus "early surgical intervention" for severe, asymptomatic, primary mitral regurgitation are addressed.

The hemodynamic effects of methylene blue when administered at the onset of cardiopulmonary bypass.

Hypotension occurs during cardiopulmonary bypass (CPB), in part because of induction of the inflammatory response, for which nitric oxide and guanylate cyclase play a central role. In this study we examined the hemodynamic effects of methylene blue (MB), an inhibitor of guanylate cyclase, administered during cardiopulmonary bypass (CPB) to patients taking angiotensin-converting enzyme inhibitors. Thirty patients undergoing cardiac surgery were randomized to receive either MB (3 mg/kg) or saline (S) after institution of CPB and cardioplegic arrest. CPB was managed similarly for all study patients. Hemodynamic data were assessed before, during, and after CPB. The use of vasopressors was recorded. All study patients experienced a similar reduction in mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) with the onset of CPB and cardioplegic arrest. MB increased MAP and SVR and this effect lasted for 40 minutes. The saline group demonstrated a persistently reduced MAP and SVR throughout CPB. The saline group received phenylephrine more frequently during CPB, and more norepinephrine after CPB to maintain a desirable MAP. The MB group recorded significantly lower serum lactate levels despite equal or greater MAP and SVR. In conclusion, administration of MB after institution of CPB for patients taking angiotensin-converting enzyme inhibitors increased MAP and SVR and reduced the need for vasopressors. Furthermore, serum lactate levels were lower in MB patients, suggesting more favorable tissue perfusion.

Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data.

BACKGROUND: Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. METHODS: We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). FINDINGS: We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). INTERPRETATION: In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. FUNDING: None.

Long-term survival after use of internal thoracic artery in octogenarians is gender related.

OBJECTIVE: The goal of this study is to assess the benefits of a left internal thoracic artery as a bypass conduit in octogenarians undergoing elective coronary artery bypass grafting. We hypothesize that there is no survival advantage and that outcome may be gender related. METHODS: In a retrospective analysis of 1141 octogenarians (aged >80 years) undergoing isolated coronary artery bypass grafting from 1996 to 2012, patients were divided into 2 groups: Group I (coronary artery bypass grafting-left internal thoracic artery) included 870 patients (339 female/531 male), and group II (coronary artery bypass grafting-saphenous vein graft) included 271 patients (131 female/140 male). RESULTS: The overall 30-day mortality was 5.7%: 4.3% in group I and 7.0% in group II (P = .1). Group II had a lower trend of any postoperative complication (P = .05) and pneumonia (P = .05). When analyzed by gender, there were no discernable differences in long-term survival for male patients in group I (65% at 5 years and 29% at 10 years) versus male patients in group II (65% at 5 years and 31% at 10 years) (P = .2). However, survival was significantly greater for female patients in group I (70% at 5 years and 35% at 10 years) versus female patients in group II (63% at 5 years and 21% at 19 years) (P = .01). Multiple logistic and Cox regression analysis showed that left internal thoracic artery use is associated with improved survival in female patients (hazard ratio [HR], 0.72; confidence interval [CI], 0.56-0.93) but not in male patients (HR, 1.14; CI, 0.9-1.4). Advanced age was associated with an increased risk of mortality (HR, 1.08 per year; CI, 1.05-1.1). Both patient age (P = .01) and Society of Thoracic Surgeons-predicted 30-day mortality (P = .03) remain in the final model for 30-day mortality. The benefit of the left internal thoracic artery after coronary artery bypass grafting in octogenarians may be gender related. CONCLUSIONS: This study shows that the benefit of the left internal thoracic artery in the octogenarian population undergoing coronary artery bypass grafting may be gender related. For elderly female patients, the use of the left internal thoracic artery as a bypass conduit was associated with better long-term survival, whereas no significant difference was found among the male population. The use of the left internal thoracic artery was associated with a greater postoperative pulmonary morbidity for the study population as a whole. The present study does not refute the benefit of the left internal thoracic artery-left anterior descending graft, but instead distinguishes a subset who might benefit more.

A randomized comparison of different ventilator strategies during thoracotomy for pulmonary resection.

OBJECTIVE: Protective lung ventilation is reported to benefit patients with acute respiratory distress syndrome. It is not known whether protective lung ventilation is also beneficial to patients undergoing single-lung ventilation for elective pulmonary resection. METHODS: In an institutional review board-approved prospective randomized trial, 34 patients undergoing elective pulmonary resection requiring single-lung ventilation were enrolled. Informed consent was obtained. Patients were randomized to 1 of 2 groups: (1) high tidal volume (Hi-TV) of 10 mL/kg, rate of 7 breaths/min, and zero positive end-expiratory pressure or (2) low tidal volume (Lo-TV) of 5 mL/kg, rate of 14 breaths/min, and 5 cmH2O positive end-expiratory pressure. Ventilator settings were continued during both double- and single-lung ventilation. Pulmonary functions, hemodynamics, and postoperative outcomes were recorded. RESULTS: Patient demographics, operative characteristics, intraoperative hemodynamics, and postoperative pain and sedation scores were similar between the 2 groups. During most time periods, airway pressures (peak and plateau) were significantly higher in the Hi-TV group; however, plateau pressures remained less than 30 cmH2O at all times for all patients. The Hi-TV group had significantly lower arterial carbon dioxide tension, less arterial carbon dioxide tension-end-tidal carbon dioxide gradient, lower alveolar dead space ratio, and higher dynamic pulmonary compliance. There were no differences in postoperative morbidity and hospital days between the 2 groups, but atelectasis scores on postoperative days 1 and 2 were lower in the Hi-TV group. CONCLUSIONS: The use of Hi-TV during single-lung ventilation for pulmonary resection resulted in no increase in morbidity and was associated with less hypercarbia, less dead space ventilation, better dynamic compliance, and less postoperative atelectasis.

The effects of vasoactive agents on flow through saphenous vein grafts during lower-extremity peripheral vascular surgery.

PURPOSE: The purpose of this study was to assess the effects of hemodynamic alterations on vein graft flow during peripheral vascular surgery. It was hypothesized that vasopressors can be administered without compromising flow through the vein grafts. SETTING: Tertiary care center, university medical center. STUDY DESIGN: Randomized placebo-controlled double-blinded study. METHODS: The effects of phenylephrine, epinephrine, milrinone, intravenous fluid, and placebo on newly constructed peripheral vein grafts were assessed in 60 patients (12 patients in each of 5 groups). Systemic and central hemodynamics were measured by using intra-arterial and pulmonary artery catheters. Vein graft flow was measured by using a transultrasonic flow probe (Transultrasonic Inc, Ithaca, NY). RESULTS: Phenylephrine increased systemic mean blood pressure (mBP) (68.2-94.0 mmHg, p < 0.01), systemic vascular resistance (SVR) (1,091-1,696 dynes x sec x cm(-5), p < 0.001), and vein graft flow (39.5-58.9 mL/min, p < 0.01), whereas cardiac output remained unchanged. Epinephrine resulted in increased cardiac output (4.4-6.9 L/min, p < 0.01) and mBP (72.7-89.1 mmHg, p < 0.01), whereas vein graft flow was reduced in 6 of 12 patients. Intravenous fluid administration resulted in a relatively smaller increase in graft flow (37.6-46.0 mL/min, p < 0.05), an increase in cardiac output, and an insignificant decrease in SVR. Other treatments had either little or no effect on vein graft flow. CONCLUSION: The study hypothesis was partly supported. Although both phenylephrine and epinephrine increased blood pressure, only the former increased vein graft flow in all patients. In conjunction with increases in graft flow after fluid administration, these data suggest that factors affecting vein graft flow are not just simply related to systemic hemodynamics.

Assessment of the tricuspid valve: a comparison of four transesophageal echocardiographic windows.

OBJECTIVE: Tricuspid valve annular dilation is associated with persistent tricuspid valve regurgitation (TR) after cardiac surgery. The purpose of this study is to compare assessment of the tricuspid valve annulus from 4 different echocardiographic windows. DESIGN: Prospective study. SETTING: Single tertiary care hospital. PATIENTS: Twenty patients undergoing cardiac surgery, including right atriotomy. METHODS: Measurements of the tricuspid valve annular diameter during ventricular diastole (TVADd) and of TR jet dimensions, obtained from 3 different transesophageal and 1 transgastric echocardiographic window, were compared with each other and with that measured by the surgeon during cardiopulmonary bypass. Data were compared using correlation statistics, bias analysis, and analysis of variance for repeated measures. RESULTS: TVAD measured by the surgeon both agreed and correlated best with TVADd measured from the transgastric right ventricular inflow/outflow window (r = 0.98; mean bias 0.04 cm). The proximal TR jet widths and TR jet lengths were larger when measured from midesophageal 4-chamber and midesophageal right ventricular inflow/outflow windows compared with other windows (p < 0.01). CONCLUSION: TVADd was more accurately measured from transgastric windows, whereas the measurements of the TR jet were greater from esophageal windows. These data support imaging from multiple windows to obtain a more comprehensive assessment of the tricuspid valve anatomy and function.

Inotropes improve right heart function in patients undergoing aortic valve replacement for aortic stenosis.

UNLABELLED: The administration of inotropes after aortic valve replacement (AVR) for aortic stenosis (AS) is controversial. Issues include the risk of left ventricular (LV) systolic outflow obstruction (LVOTO) and the proper treatment of diastolic dysfunction for patients in whom LV systolic function is often preserved and subsequently improved. In this study, we assessed the hemodynamic benefits of inotropes for patients undergoing AVR for AS. Thirty-four patients were prospectively randomized to one of three groups: epinephrine, milrinone, or placebo. Hemodynamic and echocardiographic data were obtained before and immediately after cardiopulmonary bypass (CPB). Data were also obtained before and after increases in ventricular preload to assess the effects of inotropes on diastolic function. The use of inotropes was associated with significantly larger increases in right ventricular (RV) (placebo, 0.5%; epinephrine, +9%; milrinone, +8%; P < 0.01) and LV (placebo, +7%; epinephrine, +18%; milrinone, +20%; P = 0.07) ejection fractions (EF) and cardiac output after CPB. Changes in cardiac output and index were more strongly correlated with changes in RVEF (r = 0.56, P < 0.01; r = 0.47, P < 0.01, respectively) than with LVEF (r = 0.22, r = 0.08). Of all patients receiving epinephrine or milrinone, only one (1 of 22) had a decrease in RVEF, whereas 6 of 12 patients receiving placebo had a reduction in RVEF from pre-CPB to post-CPB. Correspondingly, for LVEF, 1 of 22 patients receiving inotropes had a decrease in LVEF, whereas 3 of 12 placebo patients had a reduction in LVEF from pre-CPB to post-CPB. No patient had evidence of LVOTO. Inotropes improved hemodynamics after AVR for AS. This was attributable more to improved RV function than to changes in LV function. Although there were no changes in diastolic function, it is possible that this study did not allow significant timing to observe benefits of inotropes on diastolic function in this setting. IMPLICATIONS: Compared with placebo, both epinephrine and milrinone similarly improved biventricular performance after aortic valve replacement, with a greater impact on right ventricular function. Choice of either inotropic drug should be driven by blood pressure and hemodynamic goals in this setting.

Precardiopulmonary bypass right ventricular function is associated with poor outcome after coronary artery bypass grafting in patients with severe left ventricular systolic dysfunction.

UNLABELLED: Patients with severe left ventricular systolic dysfunction (LVSD) undergoing coronary artery bypass grafting (CABG) have an increased risk for morbidity and mortality. The purpose of this study was to assess the association of pre-CABG right ventricular (RV) function with outcome for patients with severe LVSD. We performed a retrospective evaluation of 41 patients with severe LVSD (left ventricular ejection fraction [LVEF] < or =25%) scheduled for nonemergent CABG. Data were obtained from review of medical records, transesophageal echocardiography tapes, and phone interview. The pre- and post-cardiopulmonary bypass (CPB) LVEF and the RV fractional area of contraction (RVFAC) were calculated by using intraoperative transesophageal echocardiography. Group 1 patients had an RVFAC < or =35% (n = 7), whereas Group 2 patients had RVFAC >35% (n = 34). The durations of mechanical ventilation and of intensive care unit and hospital stays are presented as the median. Pre-CABG LVEF was similar between Groups 1 and 2 (15.8% +/- 3.3% versus 17.8% +/- 3.9%). Compared with Group 2, Group 1 patients required greater duration of mechanical ventilation (12 days versus 1 day; P < 0.01), longer intensive care unit (14 versus 2 days; P < 0.01) and hospital (14 versus 7 days; P = 0.02) stays, had a more frequent incidence and severity of LV diastolic dysfunction, and had a smaller change in LVEF immediately after CPB (4.1% +/- 8.3% versus 12.5% +/- 9.2%; P = 0.03). All Group 1 patients died of cardiac causes within 2 yr of surgery; five died during the same hospital admission. Three Group 2 patients died: one of colon cancer at 18 mo after CABG and two of cardiac causes 24 and 48 mo after surgery. A fourth patient was awaiting cardiac transplantation 4 yr after surgery. The remaining Group 2 patients were New York Heart Association Classification I or II. For patients with severe LVSD undergoing CABG, pre-CPB RV dysfunction was associated with poor outcome. Patients with RVFAC >35% had a relatively uneventful perioperative course and good long-term survival, whereas patients with RVFAC < or =35% had a poor early and late outcome. Assessment of RV function is useful to further assess the risk of CABG. IMPLICATIONS: Right ventricular function before cardiopulmonary bypass is associated with poor outcome after coronary artery surgery in patients with poor left ventricular function.