Passive leg raising-induced changes in pulse pressure variation to assess fluid responsiveness in mechanically ventilated patients: a multicentre prospective observational study.

BACKGROUND: Passive leg raising-induced changes in cardiac index can be used to predict fluid responsiveness. We investigated whether passive leg raising-induced changes in pulse pressure variation (ΔPPVPLR) can also predict fluid responsiveness in mechanically ventilated patients. METHODS: In this multicentre prospective observational study, we included 270 critically ill patients on mechanical ventilation in whom volume expansion was indicated because of acute circulatory failure. We did not include patients with cardiac arrythmias. Cardiac index and PPV were measured before/during a passive leg raising test and before/after volume expansion. A volume expansion-induced increase in cardiac index of >15% defined fluid responsiveness. To investigate whether ΔPPVPLR can predict fluid responsiveness, we determined areas under the receiver operating characteristic curves (AUROCs) and grey zones for relative and absolute ΔPPVPLR. RESULTS: Of the 270 patients, 238 (88%) were on controlled mechanical ventilation with no spontaneous breathing activity and 32 (12%) were on pressure support ventilation. The median tidal volume was 7.1 (inter-quartile range [IQR], 6.6-7.6) ml kg-1 ideal body weight. One hundred sixty-four patients (61%) were fluid responders. Relative and absolute ΔPPVPLR predicted fluid responsiveness with an AUROC of 0.92 (95% confidence interval [95% CI], 0.88-0.95; P<0.001) each. The grey zone for relative and absolute ΔPPVPLR included 4.8% and 22.6% of patients, respectively. These results were not affected by ventilatory mode and baseline characteristics (type of shock, centre, vasoactive treatment). CONCLUSIONS: Passive leg raising-induced changes in pulse pressure variation accurately predict fluid responsiveness with a small grey zone in critically ill patients on mechanical ventilation. CLINICAL TRIAL REGISTRATION: NCT03225378.

Preload dependency determines the effects of phenylephrine on cardiac output in anaesthetised patients: A prospective observational study.

BACKGROUND: Although phenylephrine is widely used in the operating room to control arterial pressure, its haemodynamic effects remain controversial. OBJECTIVE: We hypothesised that the effect of phenylephrine on cardiac output is affected by preload dependency. DESIGN: A prospective observational study. SETTING: Single-centre, University Hospital of Caen, France. PATIENTS: Fifty ventilated patients undergoing surgery were studied during hypotension before and after administration of phenylephrine. MAIN OUTCOME MEASURES: Cardiac index (CI), stroke volume (SV), corrected flow time, mean arterial pressure, pulse pressure variations (PPV) and systemic vascular resistance index were used to assess effects of changes in preload dependency. RESULTS: Twenty seven (54%) patients were included in the preload-dependent group (PPV ≥ 13%) and 23 (46%) in the preload-independent group (PPV < 13%) before administration of phenylephrine. For the whole cohort, phenylephrine increased mean arterial pressure [58 (±8) mmHg vs. 79 (±13) mmHg; P < 0.0001] and calculated systemic vascular resistance index [2010 (1338; 2481) dyn s cm m vs. 2989 (2155; 3870) dyn s cm m; P < 0.0001]. However, CI and SV decreased in the preload-independent group [2.3 (1.9; 3.7) l min m vs. 1.8 (1.5; 2.7) l min m; P < 0.0001 and 65 (44; 81) ml vs. 56 (39; 66) ml; P < 0.0001 for both] but not in the preload-dependent group [respectively 2.1 (1.8; 3.5) l min m vs. 2.1 (1.8; 3.3) l min m; P = 0.168 and 49 (41; 67) ml vs. 53 (41; 69) ml; P = 0.191]. Corrected flow time increased [294 (47) ms vs. 306 (56) ms; P = 0.031], and PPV decreased [17 (15; 19) % vs.12 (14; 16) %; P < 0.0003] only in the PPV at least 13% group. CONCLUSION: The effects of phenylephrine on CI and SV depend on preload. CI and SV decreased in preload-independent patients through increase in afterload, but were unchanged in those preload-dependent through increased venous return.

Near-Infrared Spectroscopy Hemoglobin Index Measurement During Fluid Challenge: A Prospective Study in Cardiac Surgery Patients.

OBJECTIVE: Little is known about changes in near-infrared spectroscopy-derived tissue hemoglobin index (HbI). The authors tested the hypothesis that absolute values and changes in brain hemoglobin index (HbIb) and skeletal muscle hemoglobin index (HbIm) could differ from the reference arterial hemoglobin (Hb) during fluid challenge. DESIGN: A prospective, monocenter observational study. SETTING: A 16-bed cardiac surgical intensive care unit in a teaching university hospital. PARTICIPANTS: Fifty consecutive adult patients. INTERVENTIONS: Investigation before and after a fluid challenge. MEASUREMENTS AND MAIN RESULTS: Simultaneous comparative Hb, HbIb and HbIm data points were collected from a blood-gas analyzer and the EQUANOX device (Nonin Medical Inc., Plymouth, MN). Correlations were determined by linear regression. No significant relationship was found between absolute values of Hb and HbIb before (R(2)= 0.04, p = 0.627) and after (R(2) = 0.00006, p = 0.956) fluid challenge. No significant relationship was found between absolute values of Hb and HbIm before (R(2)= 0.030, p = 0.226) and after (R(2) = 0.05, p = 0.117) the fluid challenge. No significant relationship was found between changes in Hb and HbIb (R(2)= 0.26, p = 0.263) and between changes in Hb and HbIm (R(2) = 0.001, p = 0.801) after the fluid challenge. Bland-Altman analysis showed a poor concordance between changes in Hb and HbIb, and changes in Hb and HbIm, with large limits of agreement. CONCLUSIONS: HbIb and HbIm cannot be used to provide continuous noninvasive estimation of Hb, and trends in HbIb and HbIm cannot be considered as noninvasive surrogates for the trend in Hb after cardiac surgery.

Cerebral and somatic near-infrared spectroscopy measurements during fluid challenge in cardiac surgery patients: a descriptive pilot study.

OBJECTIVE: Little is known about changes in near-infrared spectroscopy (NIRS)-derived cerebral (rSO(2)b) and somatic (rSO(2)s) oxygen saturation during a fluid challenge. The authors tested the hypothesis that they could differ from central venous oxygen saturation (ScvO(2)) and from one site to another. DESIGN: A prospective observational study. SETTING: A teaching university hospital. PARTICIPANTS: Fifty consecutive adult patients. INTERVENTIONS: Admission to the intensive care unit after cardiac surgery and investigation before and after a fluid challenge. MEASUREMENTS AND MAIN RESULTS: Simultaneous comparative ScvO(2), rSO(2)b, and rSO(2)s data points were collected from a blood-gas analyzer and the EQUANOX monitor (Nonin Medical, Inc, Plymouth, MN). Correlations were determined by linear regression. Multiple stepwise linear regression models were used to assess independent variables associated with changes in ScvO(2), rSO(2)b, and rSO(2)s. A statistically significant relationship was found between absolute values of ScvO(2) and rSO(2)b (r = 0.42, p < 0.001) but not between absolute values of ScvO(2) and rSO(2)s (r = 0.18, p = 0.066). No relationship was found between percent changes in ScvO(2) and rSO(2)b (r = 0.05, p = 0.715) and between percent changes in ScvO(2) and rSO(2)s (r = 0.02, p = 0.886) after the fluid challenge. Cardiac index contributed to the prediction of changes in ScvO(2) (regression coefficient = -4.09, p = 0.006), whereas the mean arterial pressure contributed to the prediction of changes in rSO(2)b (regression coefficient = -0.05, p = 0.027). CONCLUSIONS: rSO(2)b and rSO(2)s cannot be used to provide noninvasive estimation of ScvO(2), and trends in rSO(2)b and rSO(2)s cannot be considered as noninvasive surrogates for the trend in ScvO(2) after cardiac surgery. Different independent variables contribute to the prediction of ScvO(2), rSO(2)b, and rSO(2)s.

Resection of a cardiac tumour with reconstruction of the atria and the superior vena cava.

Cardiac tumours are very rare and their complete resection, when feasible, remains the only curative treatment. We present the case of a patient who had aortic stenosis. The routine preoperative workup also identified stenosis in the left anterior descending and right coronary arteries, and most importantly, an invasive tumour at the confluence of the superior vena cava-right atrium-left atrium. After discussion by the heart team, and as is usually done in our department for non-complex right coronary lesions, the stenosis was treated by inserting a stent. The patient was operated on for an aortic valve replacement with a concomitant left internal mammary artery to left anterior descending artery coronary artery bypass graft. In addition, the tumour was completely resected surgically. Reconstruction included a patch for the left atrium, another for the right atrium and a Dacron tube for the superior vena cava. Histological analysis confirmed the complete resection of a cardiac hibernoma. Three months after the surgery, the patient is doing well without any symptoms.

A comparison of endotracheal bioimpedance cardiography and transpulmonary thermodilution in cardiac surgery patients.

OBJECTIVES: The authors hypothesized that bioimpedance cardiography measured by the Endotracheal Cardiac Output Monitor (ECOM; ConMed, Utica, NY) is a convenient and reliable method for both cardiac index (CI) assessment and prediction in fluid responsiveness. DESIGN: A prospective observational study. SETTING: A teaching university hospital. PARTICIPANTS: Twenty-five adult patients. INTERVENTIONS: Admission to the intensive care unit after conventional cardiac surgery and investigation before and after a fluid challenge. MEASUREMENTS AND MAIN RESULTS: Simultaneous comparative CI data points were collected from transpulmonary thermodilution (TD) and ECOM. Correlations were determined by linear regression. Bland-Altman analysis was used to compare the bias, precision, and limits of agreement. The percentage error was calculated. Pulse-pressure variations (PPVs) and stroke-volume variations (SVVs) before fluid challenge were collected to assess their discrimination in predicting fluid responsiveness. A weak but statistically significant relationship was found between CI(TD) and CI(ECOM) (r = 0.31, p = 0.03). Bias, precision, and limits of agreement between CI(TD) and CI(ECOM) were 0.08 L/min/m(2) (95% confidence interval, -0.11 to 0.27), 0.68 L/min/m(2), and -1.26 to 1.42 L/min/m(2), respectively. The percentage error was 51%. A nonsignificant positive relationship was found between percent changes in CI(TD) and CI(ECOM) after fluid challenge (r = 0.37, p = 0.06). Areas under the ROC curves for both PPV and SVV to predict fluid responsiveness were 0.86 (95% confidence interval, 0.67-1.06) and 0.89 (95% confidence interval, 0.74-1.04, respectively; p = 0.623). CONCLUSIONS: Continuous measurements of CI under dynamic conditions are consistent and easy to obtain with ECOM although not interchangeable with transpulmonary thermodilution. SVV given by ECOM is a dynamic parameter that predicts fluid responsiveness with good accuracy and discrimination.

Recent improvement in operative techniques lead to lower pacemaker rate after Perceval implant.

OBJECTIVES: Our goal was to compare pacemaker rate usage following two different operating techniques for implanting the Perceval aortic valve replacement. METHODS: In this retrospective, single-centre study, we studied patients with isolated or concomitant Perceval aortic valve replacement operated on first between April 2013 and January 2016, following traditional operating techniques, with patients operated on between January 2016 and December 2020, after the adoption of a modified protocol based on different annulus sizing, higher positioning of the valve and no ballooning after valve deployment was adopted. The operations were performed by 2 surgeons, and patients were followed-up for a period of 30 days. RESULTS: A total of 286 patients, with a mean age of 77 (4.9) years, had Perceval valves implanted during the study period, of which 79% were isolated aortic valve procedures. Most patients (66.8%) underwent minimally invasive procedures. Cross-clamp time was 55.1 (17.6) min. The overall postoperative pacemaker insertion rate was 8.4%, which decreased decisively after the 2016 change in the implant protocol (16% vs 5.6%; P = 0.005), adjusted odds ratio of 0.31 (95% confidence interval: 0.13-0.74, P = 0.012). Univariable and multivariable analysis showed that larger valve size (P = 0.01) and ballooning (P = 0.002) were associated with higher risk of implanting a pacemaker. Postoperative 30-day mortality was of 4.5%. CONCLUSIONS: Improvement in the operating techniques for implanting the Perceval valve may decrease the rate of pacemakers implanted postoperatively. Although further studies are needed to confirm these results, such a risk reduction may lead to wider use of Perceval valves in the future, potentially benefiting patients who are suitable candidates for minimally invasive surgery.

Reconstruction of a large pulmonary artery aneurysm using a vascular prosthesis.

A pulmonary artery aneurysm is a rare, heterogeneous disease for which there are currently no surgical guidelines. We present the case of a symptomatic patient presenting with a large aneurysm of the distal pulmonary trunk and left pulmonary artery. The aneurysm was resected through a full median sternotomy under cardiopulmonary bypass and aortic cross-clamping. The reconstruction was performed using a straight vascular prosthesis to connect the proximal pulmonary trunk to the left pulmonary artery with the lateral reimplantation of the right pulmonary artery. We find this surgical technique to be simple, effective, and reproducible by colleagues encountering similar cases.

Right anterior minithoracotomy with total central cannulation.

A right anterior minithoracotomy is gaining wider acceptance among the members of the surgical community for the treatment of isolated aortic valve replacement. Usually, the cardiopulmonary bypass circuit is implanted either totally peripherally or with 1 cannula in a central position and the other in a peripheral one. This procedure has its drawbacks because it adds potential peripheral morbidity during or after the operation. At our center, during the last year, we have developed some tips and tricks in order to establish in most of the patients a total central cardiopulmonary bypass procedure. We explain this technique in our video tutorial. We think that this approach may help other surgical teams to embrace a right anterior minithoracotomy because it is similar to what we do routinely by sternotomy.

Reversed C-shaped Scanner-guided Ministernotomy for Isolated Aortic Valve Replacement.

Here we present our technique of aortic valve replacement through a reversed C-shaped ministernotomy in 36 patients operated between 2017 and 2019. All patients had a preoperative computed tomography that guided the surgical approach. The sternum was incised at the level of the first and third or the second and fourth intercostal spaces. Cross-clamp time was of 65.2 ± 15.9 minutes. Median extubation time was of 2 hours. There was no postoperative 30-day mortality. Because the upper and lower parts of the sternum remain intact, this approach may improve postoperative thoracic stability.

The Ross procedure in adults patients with reconstruction of the RVOT with a bioprosthetic valve.

The Ross procedure is now a well established treatment for aortic valve pathology in young adult patients. However, there are several technical aspects of this operation that are still under debate. One of them is the necessity for reconstruction of the right ventricular outflow tract. Cryopreserved or decellularized pulmonary homografts are the gold standard but, in some cases, and especially in urgent patients, their availability cannot be guaranteed. Stentless xenografts (such as the Medtronic Freestyle Aortic Root) can be inappropriate for some patients with large right outflow tracts, because it can be difficult to suture them without tension. The use of bio conduits handmade using straight Dacron grafts and stented xenografts can be helpful as a third choice.  In this video tutorial we demonstrate our technique for right ventricular outflow tract reconstruction in a young adult patient. We believe that our technique should be included in the armamentarium of every Ross surgeon for use in adult patients. However, long-term outcomes for these stented xenografts in the right outflow position should be carefully evaluated in the future.

Standardized loop technique for mitral valve repair offers good midterm results.

BACKGROUND: We reviewed the midterm results of our approach for mitral valve repair with the use of standardized loops. METHODS: In a retrospective single-center study, mitral repairs performed between November 2015 and December 2019 with the standardized loop technique were included. Predefined loops of 15 and 25 mm (Gore-Tex) were implanted for posterior or anterior mitral prolapses, respectively. Isolated or concomitant mitral repairs were performed by either a sternotomy or minithoracotomy. Mean follow-up was 25.3 ± 14.7 months. RESULTS: Among 92 patients operated on for mitral repair during this period, 65 had repair with the standardized loop technique. They were mostly men (73.8%) and the mean age was 65.1 ± 9.7 years. Valve prolapse was mainly posterior (87.7%), and cordal rupture was seen in 81.5% of cases. The procedures were carried out by a minithoracotomy in 49.2% of patients. Isolated mitral repairs represented 63.1% of cases. Crossclamp and bypass times were 102 ± 22.8 min and 144.7 ± 34.9 min, respectively. The mean number of loops implanted was 2.7 ± 0.9. No patient left the operating room with moderate or severe mitral regurgitation. Postoperative morbidity was 18.4% (12 patients) and 30-day mortality was 3.1% (2 patients). Overall 4-year survival and freedom from reoperation for mitral repair failure were 84.4% and 91.7%, respectively. CONCLUSIONS: The standardized loop technique for mitral repair showed good midterm results. This technique can be valuable in the armamentarium of mitral repairs. Further evaluation is needed for long-term follow-up.

Severe Acute Proximal Pulmonary Embolism and COVID-19: A Word of Caution.

Acute pulmonary embolism is an uncharacteristic presentation in patients with coronavirus 2019 (COVID-19). Here we describe the case of a young woman presenting with severe pulmonary embolism, without any associated symptoms of infections. A clot in a patent foramen ovale was noted. Despite emergency surgical embolectomy, her clinical conditions continued to deteriorate. She was put on extracorporeal life support and tested positive for COVID-19. She died of multiorgan failure on day 10. COVID-19 may have a thrombogenic effect, and it may need to be considered in cases of pulmonary embolism and in the absence of any obvious risk factor.

Axillary TAVR under locoregional anesthesia in a patient with peripheral artery disease.

Transcatheter aortic valve replacement (TAVR) is now a relatively commonly performed procedure and the number of eligible patients is growing exponentially.  In candidates with peripheral arterial disease, the axillary artery approach is an option worth considering. Usually TAVR performed using this approach is done under general anesthesia with tracheal intubation. At our center, however, we have developed a surgical approach to TAVR using the axillary artery under locoregional anesthesia.  This video tutorial demonstrates the technical details of our strategy. Because this procedure is extrathoracic, spares cerebral vessels, and is done under locoregional anesthesia, it is particularly suitable for fragile patients. This combination of both axillary access and locoregional anesthesia has the potential to become a primary main alternative for non-femoral TAVR patients and we hope it will be adopted also by other centers.

A Standardized Loop Technique for Mitral Valve Repair.

The loop technique is widely used for mitral valve repair. However, estimation of the correct loops' length remains challenging. We describe a standardized technique with implantation of standardized 15- and 25-mm loops for posterior and anterior mitral prolapses. The number of loops and the site of their implantation are decided after a careful surgical valve analysis. This has shown reliable results in our initial experience in eight patients both, in sternotomy and minimally invasive surgery repairs, but needs further long-term evaluation.

Assessment of macro- and micro-oxygenation parameters during fractional fluid infusion: A pilot study.

PURPOSE: The main goal of this study was to assess whether maximal fluid infusion improves both oxygen delivery (DO2) and micro-circulatory parameters during hemodilution. The secondary objective was to assess the ability of baseline micro-circulatory parameters to predict oxygen consumption (VO2) response following fluid infusion. MATERIALS AND METHODS: In a postoperative cardiac ICU, patients received repeated fluid infusion until stroke volume (SV) was maximized. Before and after each fluid expansion, macro- (DO2, VO2) and micro-circulatory oxygenation parameters were recorded [central venous oxygen saturation (ScVO2), blood lactate, difference in veno-arterial carbon dioxide tension (P(v-a)CO2), somatic and cerebral oxygen saturation (rSO2)]. Patients were classified as VO2-Responders or VO2-Non-Responders according to an increase in VO2 above or below 15%, respectively. RESULTS: After maximal fluid infusion, all patients showed improved macro- and micro-circulatory oxygenation parameters, but VO2-Responders had lower values (especially for ScVO2 and cerebral rSO2). Only baseline ScVO2 and cerebral rSO2 were useful to predict the VO2 response to maximal fluid infusion (ROCAUC 0.80 (95% CI: 0.54-0.95, P=0.012) and 0.83 (95% CI: 0.57-0.96, P=0.001). CONCLUSIONS: Maximal fluid infusion improves macro- and micro-circulatory oxygenation parameters. For VO2-Responders, only ScVO2 and cerebral rSO2 could serve as markers of tissue hypoxia.

Assessment of changes in cardiac index with calibrated pulse contour analysis in cardiac surgery: A prospective observational study.

OBJECTIVES: To assess the trending ability of calibrated pulse contour cardiac index (CIPC) monitoring during haemodynamic changes (passive leg raising [PLR] and fluid loading) compared with transpulmonary thermodilution CI (CITD). METHOD: Seventy-eight mechanically-ventilated patients admitted to intensive care with calibrated pulse contour following cardiac surgery were prospectively included and investigated during PLR, and after fluid loading. Fluid responsiveness was defined as a≥15% CITD increase after a 500ml bolus. Areas under the empiric receiver operating characteristic curves (ROCAUC) for changes in CIPC (ΔCIPC) during PLR to predict fluid responsiveness and after fluid challenge to predict an increase at least 15% in CITD after fluid loading were calculated. RESULTS: Fifty-five patients (71%) were classified as responders, 23 (29%) as non-responders. ROCAUC for ΔCIPC during PLR in predicting fluid responsiveness, its sensitivity, specificity, and percentage of patients within the inconclusive class of response were 0.67 (95% CI=0.55-0.77), 0.76 (95% CI=0.63-0.87), 0.57 (95% CI=0.34-0.77) and 68%, respectively. Bias, precision and limits of agreements and percentage error between CIPC and CITD after fluid challenge were 0.14 (95% CI: 0.08-0.20), 0.26, -0.37 to 0.64 l min(-1)m(-2), and 20%, respectively. The concordance rate was 97% and the polar concordance at 30° was 91%. ROCAUC for ΔCIPC in predicting an increase of at least 15% in CITD after fluid loading was 0.85 (95% CI: 0.76-0.92). CONCLUSION: Although ΔCIPC after fluid loading could track the direction of changes of CITD and was interchangeable with bolus transpulmonary thermodilution, PLR could not predict fluid responsiveness in cardiac surgery patients.