Bertrand Delannoy

Does the Pleth variability index indicate the respiratory-induced variation in the plethysmogram and arterial pressure waveforms?

BACKGROUND: Respiratory variations in the pulse oximeter plethysmographic waveform amplitude (&Dgr;POP) are sensitive to changes in preload and can predict fluid responsiveness in mechanically ventilated patients. However, they cannot be easily calculated from a bedside monitor. Pleth variability index (PVI, Masimo Corp., Irvine, CA) is a new algorithm that automatically calculates &Dgr;POP. The aim of our study was to test the ability of this new device to automatically and continuously monitor &Dgr;POP. METHODS: Twenty-five patients were studied after induction of general anesthesia. PVI automatically and continuously calculates the respiratory variations in the plethysmography waveform amplitude (perfusion index). Data (mean arterial blood pressure, central venous pressure, respiratory variations in arterial pulse pressure, &Dgr;POP, and PVI) were recorded at baseline in anti-Trendelenburg position and, finally, in Trendelenburg position. RESULTS: There was a significant relationship between PVI and &Dgr;POP (r = 0.92; P < 0.05). Over the 75 measurements, 42 (56%) presented a &Dgr;POP value >13%. A PVI threshold value of 11.5% was able to discriminate between &Dgr;POP >13% and &Dgr;POP ≤13% with a sensitivity of 93% and a specificity of 97%. Area under the curve for PVI to predict &Dgr;POP >13% was 0.990 ± 0.07. CONCLUSION: This study is the first to demonstrate the ability of PVI, an index automatically derived from the pulse oximeter waveform analysis, to automatically and continuously monitor &Dgr;POP. This new index has potential clinical applications for noninvasive fluid responsiveness monitoring.

Efficacy and safety of recruitment maneuvers in acute respiratory distress syndrome

Recruitment maneuvers (RM) consist of a ventilatory strategy that increases the transpulmonary pressure transiently to reopen the recruitable lung units in acute respiratory distress syndrome (ARDS). The rationales to use RM in ARDS are that there is a massive loss of aerated lung and that once the end-inspiratory pressure surpasses the regional critical opening pressure of the lung units, those units are likely to reopen. There are different methods to perform RM when using the conventional ICU ventilator. The three RM methods that are mostly used and investigated are sighs, sustained inflation, and extended sigh. There is no standardization of any of the above RM. Meta-analysis recommended not to use RM in routine in stable ARDS patients but to run them in case of life-threatening hypoxemia. There are some concerns regarding the safety of RM in terms of hemodynamics preservation and lung injury as well. The rapid rising in pressure can be a factor that explains the potential harmful effects of the RM. In this review, we describe the balance between the beneficial effects and the harmful consequences of RM. Recent animal studies are discussed.

Preload dependence indices to titrate volume expansion during septic shock: a randomized controlled trial

IntroductionIn septic shock, pulse pressure or cardiac output variation during passive leg raising are preload dependence indices reliable at predicting fluid responsiveness. Therefore, they may help to identify those patients who need intravascular volume expansion, while avoiding unnecessary fluid administration in the other patients. However, whether their use improves septic shock prognosis remains unknown. The aim of this study was to assess the clinical benefits of using preload dependence indices to titrate intravascular fluids during septic shock.MethodsIn a single-center randomized controlled trial, 60 septic shock patients were allocated to preload dependence indices-guided (preload dependence group) or central venous pressure-guided (control group) intravascular volume expansion with 30 patients in each group. The primary end point was time to shock resolution, defined by vasopressor weaning.ResultsThere was no significant difference in time to shock resolution between groups (median (interquartile range) 2.0 (1.2 to 3.1) versus 2.3 (1.4 to 5.6) days in control and preload dependence groups, respectively). The daily amount of fluids administered for intravascular volume expansion was higher in the control than in the preload dependence group (917 (639 to 1,511) versus 383 (211 to 604) mL, P = 0.01), and the same held true for red cell transfusions (178 (82 to 304) versus 103 (0 to 183) mL, P = 0.04). Physiologic variable values did not change over time between groups, except for plasma lactate (time over group interaction, P <0.01). Mortality was not significantly different between groups (23% in the preload dependence group versus 47% in the control group, P = 0.10). Intravascular volume expansion was lower in the preload dependence group for patients with lower simplified acute physiology score II (SAPS II), and the opposite was found for patients in the upper two SAPS II quartiles. The amount of intravascular volume expansion did not change across the quartiles of severity in the control group, but steadily increased with severity in the preload dependence group.ConclusionsIn patients with septic shock, titrating intravascular volume expansion with preload dependence indices did not change time to shock resolution, but resulted in less daily fluids intake, including red blood cells, without worsening patient outcome.Trial registrationClinicaltrials.gov NCT01972828. Registered 11 October 2013.

Performance of the coughassist insufflation-exsufflation device in the presence of an endotracheal tube or tracheostomy tube: a bench study.

BACKGROUND: The CoughAssist is a mechanical insufflator-exsufflator designed to assist airway secretion clearance in patients with ineffective cough. The device may benefit intubated and tracheotomized patients. We assessed the impact of various artificial airways on peak expiratory flow (PEF) with the CoughAssist. METHODS: We measured PEF and pressure at the airway opening in a lung model during insufflation-exsufflation with the CoughAssist, at 3 set pressures: 30/–30, 40/–40, and 50/–50 cm H2O, first without (control), and then with different sizes (6.5 to 8.5 mm inner diameter) of endotracheal tube (ETT) and tracheostomy tube (6, 7, and 8 mm inner diameter), compliance settings of 30 and 60 mL/cm H2O, and resistance settings of 0 and 5 cm H2O/L/s). We analyzed the relationship between PEF and pressure with linear regression. RESULTS: With compliance of 30 mL/cm H2O and 0 resistance the slope of the control relationship between PEF and pressure was statistically significantly greater than during any conditions with ETT or tracheostomy tube. Therefore, in comparison to the control, the relationship of PEF to pressure significantly went in the direction from top to bottom as the ETT or tracheostomy tube became narrower. The findings were the same with compliance of 30 mL/cm H2O and resistance of 5 cm H2O/L/s. With compliance of 60 mL/cm H2O the highest set pressure values were not achieved and some relationships departed from linearity. The control slope of the relationship between PEF and pressure with compliance of 60 mL/cm H2O and 0 resistance did not significantly differ with any ETT or tracheostomy tube. CONCLUSIONS. The artificial airways significantly reduced PEF during insufflation-exsufflation with CoughAssist; the narrower the inner diameter of the artificial airway, the lower the PEF for a given expiratory pressure.

Evaluation of Recruited Lung Volume at Inspiratory Plateau Pressure With PEEP Using Bedside Digital Chest X-ray in Patients With Acute Lung Injury/ARDS

BACKGROUND: We wanted to assess whether there was a significant relationship between recruited lung volume (Vrec) and change in density on digital processed chest x-ray measured at 2 different levels of inspiratory plateau pressure corresponding to 2 PEEP levels in patients with acute lung injury or ARDS. METHODS: In 14 subjects, PEEP 5 cm H2O and 15 cm H2O were prospectively applied in a random order for 10 min. At the end of each period, chest x-ray was taken using a digital portable device, and a pressure-volume curve of the respiratory system was performed. We also assessed PaO2, and the static and the dynamic (Cdyn,rs) compliance of the respiratory system. Change in end-expiratory lung volume between tidal breath and relaxation volume of the respiratory system was determined. Radiological attenuation was measured on chest x-rays in 4 regions of interest in the right lung, and in 3 regions of interest in the left lung, drawn in posterior intercostal spaces from top to bottom, by using dedicated software. The ratio of lung density in each region between PEEP 15 and PEEP 5 (rP15/P5) and their arithmetic mean (μP15/P5) were computed. Vrec was determined from the pressure-volume curves. RESULTS: The median value of rP15/P5 in the 98 lung levels was 0.91 (0.80–1.01), which was significantly different from 1 (P < .001). The values of rP15/P5 were not significantly different between the lung levels. The median values of Vrec and μP15/P5 were 288 (173–402) mL and 0.90 (0.80–0.97), respectively. There was a significant negative correlation between Vrec and μP15/P5 (R = −0.77, P = .01). The reduction in μP15/P5 tended to correlate with the increase in Cdyn,rs (R = −0.49, P = .077) or in PaO2 (R = −0.53, P = .05) between PEEP 15 cm H2O and PEEP 5 cm H2O. CONCLUSIONS: Digital chest x-ray done at the bedside in acute lung injury/ARDS subjects was able to detect a reduction in density between PEEP 5 cm H2O and PEEP 15 cm H2O, which correlated with Vrec.

Management and Long-Term Outcome of Patients With Chronic Neuromuscular Disease Admitted to the Intensive Care Unit for Acute Respiratory Failure: A Single-Center Retrospective Study

BACKGROUND: Patients with chronic neuromuscular disease represent less than 10% of those receiving mechanical ventilation in the intensive care unit (ICU). Little has been reported regarding either ICU management of acute respiratory failure (ARF) in the era of noninvasive mechanical ventilation (NIV) or long-term outcomes. OBJECTIVE: To describe the respiratory management of patients with chronic neuromuscular diseases admitted to our university hospital ICU for ARF, and the long-term outcomes. METHODS: We retrospectively analyzed patients with chronic neuromuscular diseases admitted to our ICU for a first episode of ARF between January 1, 1996, and February 27, 2007. We assessed severity of illness on ICU admission, respiratory management during ICU stay, and outcomes on June 15, 2008. RESULTS: During the study period, 87 patients (44 with hereditary and 43 with acquired neuromuscular diseases) had their first ARF episode that required ICU admission. In the hereditary-diseases group and the acquired-diseases group, respectively, the rates of NIV use during the ICU stay were 82% and 63% (P = .040), the intubation rates were 30% and 56% (P = .02), and the tracheotomy rates were 9% and 12% (difference not significant). At the final assessment (median 3 years) the mortality rate was 58%, and mortality was not significantly related to the type of neuromuscular disease. At final assessment, 46% of the patients were on NIV and 29% had tracheotomy. CONCLUSIONS: In our ICU, chronic neuromuscular disease is an uncommon cause of ARF, for which we often use NIV. These patients had a low probability of death in the ICU. Long-term outcome was independent of the type of neuromuscular disease.

SDRA infectieux réfractaire : place de l’oxygénation extracorporelle

Acute respiratory distress syndrome (ARDS) is a frequent cause of admission in intensive care unit. The treatment is well codified. Unfortunately some patients die because of hypoxemia despite a well-conducted medical treatment. Extracorporeal oxygenation could be the ultimate treatment for these refractory hypoxemia patients. We report two cases of patients suffering from severe ARDS who beneficiated from extracorporeal oxygenation, pointing out the interest of this technique during severe ARDS as well as the accessibility and the feasibility of the technique even apart from a specialized center.

Comparison of Alpha 200 and CoughAssist as Intermittent Positive Pressure Breathing Devices: A Bench Study

BACKGROUND: Intermittent positive pressure breathing (IPPB) is used in non-intubated patients to increase lung volume and to enhance coughing. Alpha 200 (Salvia Lifetec, Kronberg, Germany) is a specific IPPB device. CoughAssist (Respironics France, Carquefou, France) is a mechanical insufflator-exsufflator used to remove secretions in patients with inefficient cough. Both can also be used for intubated or tracheotomized patients. We assessed the impact of various artificial airways on the ability of the Alpha 200 and CoughAssist to generate insufflated volume. METHODS: We measured the insufflated volume and pressure at the airway opening in a lung model under 2 conditions of compliance (30 or 60 mL/cm H2O) at single resistance of 5 cm H2O/L/s. The devices were used at 2 set pressures: 30 and 40 cm H2O. The Alpha 200 was set at 2 inflation flows: 0.5 and 1 L/s, whereas CoughAssist was set at its highest value of 10 L/s. Measurements were done without (control) and with different size endotracheal tubes and tracheostomy cannulae. The relationships between insufflated volume and measured pressure were analyzed using linear regressions. RESULTS: The slopes and intercepts of the control relationship between insufflated volume and pressure were significantly greater with Alpha 200 at each set flow than with CoughAssist. As artificial airways were used, the insufflated volume did not differ from the control with CoughAssist, while with Alpha 200 it increased at each flow setting and for all mechanical conditions. The largest differences in insufflated volume between the 2 devices were observed for the largest endotracheal tubes and tracheostomy cannulas and for the lowest inflation flow setting in Alpha 200. These results can be explained in terms of how the devices function, as CoughAssist adapts by increasing flow, while Alpha 200 adapts by increasing inspiratory time. CONCLUSIONS: This bench study has shown that in the presence of artificial airways the value of the insufflated volume generated by the CoughAssist device was significantly lower than that generated by the Alpha 200 device.

Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients.

Total percutaneous femoral vessels cannulation for minimally invasive mitral valve surgery

BACKGROUND Minimally invasive mitral valve surgery (MIMVS) has experienced several technological changes in the last two decades. Our aim was to describe one of the most recent improvements, the utilization of a total percutaneous femoral vessels cannulation technique during MIMVS. METHODS We performed a retrospective observational analysis of this technique among 300 consecutive MIMVS patients, with particular focus on cannulation aspects of MIMVS, its success rate and potential complications. RESULTS From October 2008 to December 2012, 300 patients (60% males) were operated on. Mean age was 62.9±16.4 years. Indications for operation included mitral valve repair (93%) and mitral valve replacement (7%). Two femoral arterial catheterizations failed and required conversion to sternotomy. The complications on the arterial side were: 5 (1.6%) cases of bleeding during the introduction of Prostar leading to a preoperative surgical hemostasis; 2 (0.6%) retroperitoneal bleeds during cardiopulmonary bypass requiring difficult surgical control but with an uneventful follow-up; 6 (2%) bleeding episodes after removal of the arterial cannula easily controlled by direct surgical revision; 1 (0.3%) arterio-venous fistula requiring a surgical correction on postoperative day 32; 1 (0.3%) patient had a transitory claudication due to a superficial femoral artery thrombosis progressively compensated by the collateral circulation. There were no postoperative bleeding complications. There were no other complications linked to the femoral cannulations or to the groin occurred during the follow-up. The percentage of uneventful arterial cannulations was 80% among the first 50 patients (N=10 out of 50) and 98.8% thereafter (N=3 out of 250). CONCLUSIONS Total percutaneous femoral vessels cannulation technique is particularly suitable for MIMVS with a high success rate and few complications after a short learning curve. With the advent of the percutaneous approach, the traditional complications of the groin incision have completely disappeared in modern operations with no groin infection, hematoma or lymphocele.