Passive leg raising test induced changes in plethysmographic variability index to assess fluid responsiveness in critically ill mechanically ventilated patients with acute circulatory failure.

BACKGROUND: Passive leg raising (PLR) reliably predicts fluid responsiveness but requires a real-time cardiac index (CI) measurement or the presence of an invasive arterial line to achieve this effect. The plethysmographic variability index (PVI), an automatic measurement of the respiratory variation of the perfusion index, is non-invasive and continuously displayed on the pulse oximeter device. We tested whether PLR-induced changes in PVI (ΔPVIPLR) could accurately predict fluid responsiveness in mechanically ventilated patients with acute circulatory failure. METHODS: This was a secondary analysis of an observational prospective study. We included 29 mechanically ventilated patients with acute circulatory failure in this study. We measured PVI (Radical-7 device; Masimo Corp., Irvine, CA) and CI (Echocardiography) before and during a PLR test and before and after volume expansion of 500 mL of crystalloid solution. A volume expansion-induced increase in CI of >15% defined fluid responsiveness. To investigate whether ΔPVIPLR can predict fluid responsiveness, we determined areas under the receiver operating characteristic curves (AUROCs) and gray zones for ΔPVIPLR. RESULTS: Of the 29 patients, 27 (93.1%) received norepinephrine. The median tidal volume was 7.0 [IQR: 6.6-7.6] mL/kg ideal body weight. Nineteen patients (65.5%) were classified as fluid responders (increase in CI > 15% after volume expansion). Relative ΔPVIPLR accurately predicted fluid responsiveness with an AUROC of 0.89 (95%CI: 0.72-0.98, p < 0.001). A decrease in PVI ≤ -24.1% induced by PLR detected fluid responsiveness with a sensitivity of 95% (95%CI: 74-100%) and a specificity of 80% (95%CI: 44-97%). Gray zone was acceptable, including 13.8% of patients. The correlations between the relative ΔPVIPLR and changes in CI induced by PLR and by volume expansion were significant (r = -0.58, p < 0.001, and r = -0.65, p < 0.001; respectively). CONCLUSIONS: In sedated and mechanically ventilated ICU patients with acute circulatory failure, PLR-induced changes in PVI accurately predict fluid responsiveness with an acceptable gray zone. TRIAL REGISTRATION: ClinicalTrials.govNCT03225378.

Invasive Tracheobronchial Aspergillosis in Critically Ill Patients with Severe Influenza. A Clinical Trial.

Rationale: Invasive tracheobronchial aspergillosis (ITBA) is an uncommon but severe clinical form of invasive pulmonary aspergillosis in which the fungal infection is entirely or predominantly confined to the tracheobronchial tree.Objectives: To analyze the diagnostic and prognostic differences between tracheobronchial aspergillosis and pulmonary aspergillosis without tracheobronchial lesions among patients admitted to the ICU with severe influenza.Methods: This retrospective, observational study included critically ill patients with influenza associated with pulmonary aspergillosis from three hospital ICUs between 2010 and 2019. Patient characteristics and clinical and mycologic data at admission and during ICU stay were collected in a database to evaluate variables in the two groups.Measurements and Main Results: Thirty-five patients admitted to the ICU with severe influenza and pulmonary aspergillosis were included. Ten patients were included in the group with ITBA (n = 10 of 35; 28.6%), and 25 patients were included in the group without ITBA. The group with ITBA comprised more patients with active smoking, diabetes mellitus, and higher severity scores (Simplified Acute Physiology Score II). Ninety-day mortality rates in the groups with and without ITBA were 90% and 44%, respectively (P = 0.02). Moreover, significantly higher serum 1,3-ß-d-glucan and galactomannan and BAL fluid galactomannan concentrations were observed in the group with ITBA compared with the group without ITBA (P < 0.0001, P = 0.003, and P = 0.008, respectively).Conclusions: ITBA was associated with higher severity scores, mortality, and serum and BAL fluid galactomannan and 1,3-ß-d-glucan concentrations than invasive pulmonary aspergillosis without tracheobronchial lesions. ITBA should be systematically researched by bronchoscopic examination in ICU patients with concomitant pulmonary aspergillosis and influenza.Clinical trial registered with www.clinicaltrials.gov (NCT04077697).

Rescue therapeutic strategy combining ultra-protective mechanical ventilation with extracorporeal CO2 removal membrane in near-fatal asthma with severe pulmonary barotraumas: A case report.

RATIONALE: Mechanical ventilation of severe acute asthma is still considered a challenging issue, mainly because of the gas trapping phenomenon with the potential for life-threatening barotraumatic pulmonary complications. PATIENT CONCERNS: Herein, we describe 2 consecutive cases of near-fatal asthma for whom the recommended protective mechanical ventilation approach using low tidal volume of 6 mL/kg and small levels of PEEP was rapidly compromised by giant pneumomediastinum with extensive subcutaneousemphysema. DIAGNOSES: Near fatal asthma. INTERVENTION: A rescue therapeutic strategy combining extracorporeal CO2 removal membrane with ultra-protective extremely low tidal volume (3 mL/kg) ventilation was applied. OUTCOMES: Both patients survived hospital discharge. LESSONS: These 2 cases indicate that ECCO2R associated with ultra-protective ventilation could be an alternative to surgery in case of life-threatening barotrauma occurring under mechanical ventilation.

Acute hyperventilation increases the central venous-to-arterial PCO2 difference in stable septic shock patients.

BACKGROUND: To evaluate the effects of acute hyperventilation on the central venous-to-arterial carbon dioxide tension difference (∆PCO2) in hemodynamically stable septic shock patients. METHODS: Eighteen mechanically ventilated septic shock patients were prospectively included in the study. We measured cardiac index (CI), ∆PCO2, oxygen consumption (VO2), central venous oxygen saturation (ScvO2), and blood gas parameters, before and 30 min after an increase in alveolar ventilation (increased respiratory rate by 10 breaths/min). RESULTS: Arterial pH increased significantly (from 7.35 ± 0.07 to 7.42 ± 0.09, p < 0.001) and arterial carbon dioxide tension decreased significantly (from 44.5 [41-48] to 34 [30-38] mmHg, p < 0.001) when respiratory rate was increased. A statistically significant increase in VO2 (from 93 [76-105] to 112 [95-134] mL/min/m2, p = 0.002) was observed in parallel with the increase in alveolar ventilation. While CI remained unchanged, acute hyperventilation led to a significant increase in ∆PCO2 (from 4.7 ± 1.0 to 7.0 ± 2.6 mmHg, p < 0.001) and a significant decrease in ScvO2 (from 73 ± 6 to 67 ± 8%, p < 0.001). A good correlation was found between changes in arterial pH and changes in VO2 (r = 0.67, p = 0.002). Interestingly, we found a strong association between the increase in VO2 and the increase in ∆PCO2 (r = 0.70, p = 0.001). CONCLUSIONS: Acute hyperventilation provoked a significant increase in ∆PCO2, which was the result of a significant increase in VO2 induced by hyperventilation. The clinician should be aware of the effects of acute elevation of alveolar ventilation on ∆PCO2.

Impact of fiber-optic laryngoscopy on the weaning process from mechanical ventilation in high-risk patients for postextubation stridor.

The objective of this study was to assess the impact of fiber-optic laryngoscopy (FOL) on the weaning process from mechanical ventilation in critically ill patients with a positive cuff leak test (CLT) as compared with the current recommended strategy based on corticosteroids.In this prospective observational pilot study conducted over a 1-year period in a 15-bed ICU, CLT was systematically performed before extubation in all intubated patients having passed a spontaneous breathing trial (SBT). After the endotracheal tube cuff was deflated, cuff leak volume (CLVol) was assessed during assisted controlled ventilation. When CLT was positive (CLVol < 110 mL), patients either were evaluated using FOL by our half-time FOL-practitioner when present, or received corticosteroids.Among the 233 patients included, 34 (14.6%) had a positive CLT that hampered extubation. Seventeen were treated by corticosteroids and 17 were evaluated by FOL. In the corticosteroids group, the CLVol was still <110 mL at 24 hours in 9 patients (53%). Corticosteroids strategy merely prolonged the total duration of mechanical ventilation (7 [4-11] vs 4 [2-6] days, P = 0.01) by increasing the time between successful SBT and the moment when extubation was effectively achieved (30 [24-60] vs 1.5 [1-2] hours, P < 0.001). This resulted in 2 self-extubations (12%) and 9 FOL-guided extubations (53%) in the corticosteroids group. Massive swelling of the arytenoids was the most common feature shown by FOL. The patients evaluated by FOL who exhibited the thin anterior V-shaped opening of the vocal cords-the V sign-(n = 26, 100%) were immediately extubated without any stridor or respiratory failure afterward.In this pilot study, a FOL-based extubation strategy was feasible and reliable, and significantly reduced the duration of mechanical ventilation in patients with a positive CLT. We describe the "V sign" of FOL that safely allows a successful prompt extubation in patients considered at high risk for postextubation stridor.

Ratios of central venous-to-arterial carbon dioxide content or tension to arteriovenous oxygen content are better markers of global anaerobic metabolism than lactate in septic shock patients.

BACKGROUND: To evaluate the ability of the central venous-to-arterial CO2 content and tension differences to arteriovenous oxygen content difference ratios (∆ContCO2/∆ContO2 and ∆PCO2/∆ContO2, respectively), blood lactate concentration, and central venous oxygen saturation (ScvO2) to detect the presence of global anaerobic metabolism through the increase in oxygen consumption (VO2) after an acute increase in oxygen supply (DO2) induced by volume expansion (VO2/DO2 dependence). METHODS: We prospectively studied 98 critically ill mechanically ventilated patients in whom a fluid challenge was decided due to acute circulatory failure related to septic shock. Before and after volume expansion (500 mL of colloid solution), we measured cardiac index, VO2, DO2, ∆ContCO2/∆ContO2 and ∆PCO2/∆ContO2 ratios, lactate, and ScvO2. Fluid-responders were defined as a ≥15 % increase in cardiac index. Areas under the receiver operating characteristic curves (AUC) were determined for these variables. RESULTS: Fifty-one patients were fluid-responders (52 %). DO2 increased significantly (31 ± 12 %) in these patients. An increase in VO2 ≥ 15 % ("VO2-responders") concurrently occurred in 57 % of the 51 fluid-responders (45 ± 16 %). Compared with VO2-non-responders, VO2-responders were characterized by higher lactate levels and higher ∆ContCO2/∆ContO2 and ∆PCO2/∆ContO2 ratios. At baseline, lactate predicted a fluid-induced increase in VO2 ≥ 15 % with AUC of 0.745. Baseline ∆ContCO2/∆ContO2 and ∆PCO2/∆ContO2 ratios predicted an increase of VO2 ≥ 15 % with AUCs of 0.965 and 0.962, respectively. Baseline ScvO2 was not able to predict an increase of VO2 ≥ 15 % (AUC = 0.624). CONCLUSIONS: ∆ContCO2/∆ContO2 and ∆PCO2/∆ContO2 ratios are more reliable markers of global anaerobic metabolism than lactate. ScvO2 failed to predict the presence of global tissue hypoxia.

Repeatability of blood gas parameters, PCO2 gap, and PCO2 gap to arterial-to-venous oxygen content difference in critically ill adult patients.

The objective of this study was to examine the repeatability of blood gas (BG) parameters and their derived variables such as the central venous-to-arterial carbon dioxide tension difference (▵PCO2) and the ratio of ▵PCO2 over the central arteriovenous oxygen content difference (▵PCO2/C(a-cv)O2) and to determine the smallest detectable changes in individual patients.A total of 192 patients with arterial and central venous catheters were included prospectively. Two subsequent arterial and central venous blood samples were collected immediately one after the other and analyzed using the same point-of-care BG analyzer. The samples were analyzed for arterial and venous BG parameters, ▵PCO2, and ▵PCO2/C(a-cv)O2 ratio. Repeatability was expressed as the smallest detectable difference (SDD) and the least significant change (LSC). A change in value of these parameters exceeding the SDD or the LSC should be regarded as real.The SDDs for arterial carbon dioxide tension, arterial oxygen saturation, central venous oxygen saturation (ScvO2), and ▵PCO2 were small: ±2.06 mm Hg, ±1.23%, 2.92%, and ±1.98 mm Hg, respectively, whereas the SDDs for arterial oxygen tension (PaO2) and ▵PCO2/C(a-cv)O2 were high: ±9.09 mm Hg and ±0.57 mm Hg/mL, respectively. The LSCs (%) for these variables were 5.06, 1.27, 4.44, 32.4, 9.51, and 38.5, respectively.The repeatability of all these variables was good except for PaO2 and ▵PCO2/C(a-cv)O2 ratio for which we observed an important inherent variability. Expressed as SDD, a ScvO2 change value of at least ±3% should be considered as true. The clinician must be aware that an apparent change in these variables in an individual patient might represent only an inherent variation.

Cardiopulmonary response to exercise in patients with liver cirrhosis and impaired pulmonary gas exchange.

Maximal exercise capacity and pulmonary gas exchange are both commonly impaired in liver cirrhosis. Apart from rare cases of hepatopulmonary syndrome, it is still unknown whether these moderate pulmonary gas exchange abnormalities can alter aerobic capacity of cirrhotic patients. Resting pulmonary function tests and symptom-limited cardiopulmonary exercise testing were prospectively investigated in 30 patients with liver cirrhosis exhibiting a widened alveolar-arterial oxygen gradient (P(A-a)O(2) > 30 mm Hg at peak exercise) without pulmonary vascular dilatations at contrast-enhanced echocardiography. Data were compared with those of 30 normoxemic cirrhotic controls (matched for age, gender, body mass index, etiology and severity of liver disease, smoking habits, hemoglobin level, and beta-blocker therapy). Resting cardiopulmonary parameters were within normal range in both groups except carbon monoxide lung transfer (TLCO, 60.4 ± 2.9 vs 74.3 ± 2.8% in controls, p = 0.0004) and P(A-a)O(2) (28.8 ± 2 vs 15.3 ± 2 mm Hg in controls, p < 0.0001). Cirrhotics with impaired gas exchange during exercise exhibited a significant reduction in maximal oxygen uptake (VO(2)max, 1.18 ± 0.07 (53% predicted) vs 1.41 ± 0.07 L/min (62% predicted), p = 0.004), a higher ventilation level at ventilatory threshold (V(E)/VO(2), 39.2 ± 1.5 vs 35.3 ± 1.5, p = 0.01) without ventilatory limitation, and a greater dead space to tidal volume ratio (V(D)/V(T)max, 0.32 ± 0.01 vs 0.25 ± 0.01, p = 0.01). VO(2)max correlates negatively with V(D)/V(T)max (r(2) = 0.36; p < 0.0001). There were no differences in cardiac or metabolic response to exercise between groups. Taken together these findings suggest that clinically undetectable pulmonary vascular disorders can slightly contribute to further reduce exercise capacity of cirrhotic patients.

Impact of impaired aerobic capacity on liver transplant candidates.

BACKGROUND: Oxygen consumption at peak exercise (peak VO2) is the most accurate index of aerobic capacity (AC), which reflects the physical condition of an individual and is currently considered the gold standard for cardiorespiratory fitness. Evaluation of peak VO2 to identify high-risk candidates for liver transplantation (LT) may represent an interesting approach. The aims of this study were (a) to describe AC and identify factors independently associated with peak VO2; (b) to analyze the prognostic value of peak VO2 in patients referred for preliminary evaluation of LT; and (c) to provide preliminary data on the influence of peak VO2 on length of hospitalization and the need for oxygen support after LT. RESULTS: Peak VO2 was determined in patients referred for preliminary evaluation for LT. One hundred thirty-five candidates were included. More than half had severe alterations in peak VO2. Age, gender, model-for-end-stage liver disease (MELD) score, tobacco use, and hemoglobin were independently associated with peak VO2. Candidates with severe alterations in peak VO2 had a lower 1-year survival than others. Model-for-end-stage liver disease score and peak VO2 were independently associated with survival. In patients with a MELD above 17, those with severe alterations of peak VO2 AC had lower 1-year survival than the others. Among patients who underwent LT, those with severe impairment of peak VO2 showed a trend toward a higher mean length of hospitalization after LT and had significantly longer need for oxygen support. CONCLUSIONS: Peak VO2 is severely impaired in candidates for LT and affects survival and post-LT course. Perioperative respiratory rehabilitation programs validated in lung and heart transplantation must be tested.