Myocardial dysfunction assessed by speckle-tracking in good-grade subarachnoid hemorrhage patients (WFNS 1-2): a prospective observational study.

BACKGROUND: Cardiac complications due to non-traumatic subarachnoid hemorrhage (SAH) are usually described using classical echocardiographic evaluation. Strain imaging appears to have better sensitivity than standard echocardiographic markers for the diagnosis of left ventricular dysfunction. The aim of this study was to determine the prevalence of cardiac dysfunction defined as a Global Longitudinal Strain (GLS) ≥ - 20% in patients with good-grade SAH (WFNS 1 or 2). METHODS: Seventy-six patients with good-grade SAH were prospectively enrolled and analyzed at admission for neurocritical care. Transthoracic echocardiography was performed on days 1, 3, and 7 after hemorrhage. Routine measurements, including left ventricular ejection fraction (LVEF), were performed, and off-line analysis was performed by a blinded examiner, to determine 2-, 3-, and 4-cavity longitudinal strain and left ventricular GLS. GLS was considered altered if it was ≥ - 20%, we also interested the value of ≥ - 17%. LVEF was considered altered if it was < 50%. RESULTS: On day 1, 60.6% of patients had GLS ≥ - 20% and 21.2% of patient had GLS ≥ - 17%. In comparison, alteration of LVEF was present in only 1.7% of patients. The concordance rate between LVEF < 50% and GLS ≥ - 20% and LVEF ≥ 50% and GLS < - 20% was 46%. CONCLUSION: Strain imaging showed a higher prevalence (60.6%) of left ventricular dysfunction during the acute phase of good-grade SAH (WFNS 1 or 2) than previously described.

Ability of the Analgesia Nociception Index variations to identify a response to a volume expansion of 250 mL of crystalloids in the operating room (REVANI): a prospective observational study.

BACKGROUND: Analgesia Nociception Index (ANI) is a device based on analysis of the R-R interval and respiratory sinus arrhythmia to assess the balance between sympathetic and parasympathetic activity. The autonomic system is directly affected by load changes. Therefore, monitoring sympathetic tone and its change could theoretically allow tracking of load changes during volume expansion. The aim of the present study was to determine whether changes in ANI are able to track the increase in stroke volume caused by volume expansion (SV). METHODS: This prospective observational study included mechanically ventilated patients undergoing neurosurgery and benefiting from SV monitoring. Exclusion criteria were cardiac dysfunction, arrhythmias, beta-blockade therapy, and dysautonomia. SV was optimized by fluid administration of 250 ml of crystalloid fluid. A positive fluid increase was defined as a SV increase of 10% or more from baseline. Changes in SV and medium ANI (ANIm) were recorded before and 4 to 5 min after volume expansion. RESULTS: Sixty-nine patients had 104 fluid challenges (36 positive and 68 negative). Volume expansion resulted in a greater ANI increase in responders than in nonresponders. The change in ANIm > 5 predicted fluid responsiveness with a sensitivity of 68.4% (95% CI: 67.4% to 69.5%) and a specificity of 51.2% (95% CI: 50.1% to 52.3%). The area under the receiver operating characteristic curve was 0.546 (95% CI: 0.544 to 0.549) and appeared to be affected by remifentanil dose and baseline ANI. CONCLUSION: Changes in ANIm induced by fluid challenge is not able to predict fluid responsiveness in mechanically ventilated patients undergoing neurosurgery. TRIAL REGISTRATION: Clinical trial registration: NCT04223414.

Relationship Between Brain Tissue Oxygen and Near-Infrared Spectroscopy in Patients with Nontraumatic Subarachnoid Hemorrhage.

BACKGROUND: Continuous monitoring of cerebral oxygenation is one of the diagnostic tools used in patients with brain injury. Direct and invasive measurement of cerebral oxygenation with a partial brain oxygen pressure (PbtO2) probe is promising but invasive. Noninvasive assessment of regional transcranial oxygen saturation using near-infrared spectroscopy (NIRS) may be feasible. The aim of this study was to evaluate the interchangeability between PbtO2 and NIRS over time in patients with nontraumatic subarachnoid hemorrhage. METHODS: This retrospective study was performed in a neurocritical care unit. Study participants underwent hourly PbtO2 and NIRS measurements over 72 h. Temporal agreement between markers was described by their pointwise correlation. A secondary analysis assessed the structure of covariation between marker trajectories using a bivariate linear mixed model. RESULTS: Fifty-one patients with subarachnoid hemorrhage were included. A total of 3362 simultaneous NIRS and PbtO2 measurements were obtained. The correlation at each measurement time ranged from - 0.25 to 0.25. The global correlation over time was - 0.026 (p = 0.130). The bivariate linear mixed model confirmed the lack of significant correlation between the PbtO2 and NIRS measurements at follow-up. NIRS was unable to detect PbtO2 values below 20 mm Hg (area under the receiver operating characteristic curve 0.539 [95% confidence interval 0.536-0.542]; p = 0.928), and percentage changes in NIRS were unable to detect a decrease in PbtO2 ≥ 10% (area under the receiver operating characteristic curve 0.615 [95% confidence interval 0.614-0.616]; p < 0.001). CONCLUSIONS: PbtO2 and NIRS measurements were not correlated. There is no evidence that NIRS could be a substitute for PbtO2 monitoring in patients with nontraumatic subarachnoid hemorrhage.

The ability of Oxygen Reserve Index® to detect hyperoxia in critically ill patients.

BACKGROUND: Hyperoxia is associated with increased morbidity and mortality in the intensive care unit. Classical noninvasive measurements of oxygen saturation with pulse oximeters are unable to detect hyperoxia. The Oxygen Reserve Index (ORI) is a continuous noninvasive parameter provided by a multi-wave pulse oximeter that can detect hyperoxia. Primary objective was to evaluate the diagnostic accuracy of the ORI for detecting arterial oxygen tension (PaO2) > 100 mmHg in neurocritical care patients. Secondary objectives were to test the ability of ORI to detect PaO2 > 120 mmHg and the ability of pulse oximetry (SpO2) to detect PaO2 > 100 mmHg and PaO2 > 120 mmHg. METHODS: In this single-center study, we collected ORI and arterial blood samples every 6 h for 3 consecutive days. Diagnostic performance was estimated using the area under the receiver operating characteristic curve (AUROC). RESULTS: There were 696 simultaneous measurements of ORI and PaO2 in 62 patients. Considering the repeated measurements, the correlation between ORI and PaO2 was r = 0.13. The area under the receiver operating characteristic curve (AUROC), obtained to test the ability of ORI to detect PaO2 > 100 mmHg, was 0.567 (95% confidence interval = 0.566-0.569) with a sensitivity of 0.233 (95%CI = 0.230-0.235) and a specificity of 0.909 (95%CI = 0.907-0.910). The AUROC value obtained to test the ability of SpO2 to detect a PaO2 > 100 mmHg was 0.771 (95%CI = 0.770-0.773) with a sensitivity of 0.715 (95%CI = 0.712-0.718) and a specificity of 0.700 (95%CI = 0.697-0.703). The diagnostic performance of ORI and SpO2 for detecting PaO2 > 120 mmHg was AUROC = 0.584 (95%CI = 0.582-0.586) and 0.764 (95%CI = 0.762-0.766), respectively. The AUROC obtained for SpO2 was significantly higher than that for ORI (p < 0.01). Diagnostic performance was not affected by sedation, norepinephrine infusion, arterial partial pressure of carbon dioxide, hemoglobin level and perfusion index. CONCLUSION: In a specific population of brain-injured patients hospitalized in a neurointensive care unit, our results suggest that the ability of ORI to diagnose hyperoxia is relatively low and that SpO2 provides better detection.

Utility of changes in end-tidal carbon dioxide after volume expansion to assess fluid responsiveness in the operating room: a prospective observational study.

BACKGROUND: From a physiological viewpoint, changes in end-tidal carbon dioxide (EtCO2) could be a simple, noninvasive, and inexpensive way to monitor changes in cardiac index. This study aimed to assess the utility of changes in EtCO2 as a marker of fluid responsiveness after volume expansion in the operating room. METHODS: A prospective observational study was conducted in a tertiary university teaching hospital, from August 2018 to February 2019. A total of 109 non-consecutive, mechanically ventilated adults undergoing neurosurgery in the supine position with cardiac output monitors were included. Patients with major respiratory disease, arrhythmia, or heart failure were excluded. Volume expansion with 250 ml of saline 0.9% was performed over 10 min to maximise cardiac output during surgery, according to current guidelines. A positive fluid challenge was defined as an increase in stroke volume index of more than 10% from baseline. Changes in stroke volume index (monitored using pulse contour analysis) and EtCO2 were recorded before and after infusion. RESULTS: A total of 242 fluid challenges in 114 patients were performed, of which 26.9% were positive. Changes in EtCO2 > 1.1% induced by infusions had utility for identifying fluid responsiveness, with a sensitivity of 62.9% (95% confidence interval [CI], 62.5-63.3%) and a specificity of 77.8% (95% CI, 77.6-78.1%). The area under the receiver operating characteristic curve for changes in EtCO2 after volume expansion was 0.683 (95% CI, 0.680-0.686). CONCLUSIONS: Changes in EtCO2 induced by rapid infusion of 250 ml saline 0.9% lacked accuracy for identifying fluid responsiveness in mechanically ventilated patients in the operating room. CLINICAL TRIAL REGISTRATION: NCT03635307.

End-expiratory occlusion maneuver to predict fluid responsiveness in the intensive care unit: an echocardiographic study.

BACKGROUND: In mechanically ventilated patients, an increase in cardiac index during an end-expiratory-occlusion test predicts fluid responsiveness. To identify this rapid increase in cardiac index, continuous and instantaneous cardiac index monitoring is necessary, decreasing its feasibility at the bedside. Our study was designed to investigate whether changes in velocity time integral and in peak velocity obtained using transthoracic echocardiography during an end-expiratory-occlusion maneuver could predict fluid responsiveness. METHODS: This single-center, prospective study included 50 mechanically ventilated critically ill patients. Velocity time integral and peak velocity were assessed using transthoracic echocardiography before and at the end of a 12-sec end-expiratory-occlusion maneuver. A third set of measurements was performed after volume expansion (500 mL of saline 0.9% given over 15 minutes). Patients were considered as responders if cardiac output increased by 15% or more after volume expansion. RESULTS: Twenty-eight patients were responders. At baseline, heart rate, mean arterial pressure, cardiac output, velocity time integral and peak velocity were similar between responders and non-responders. End-expiratory-occlusion maneuver induced a significant increase in velocity time integral both in responders and non-responders, and a significant increase in peak velocity only in responders. A 9% increase in velocity time integral induced by the end-expiratory-occlusion maneuver predicted fluid responsiveness with sensitivity of 89% (95% CI 72% to 98%) and specificity of 95% (95% CI 77% to 100%). An 8.5% increase in peak velocity induced by the end-expiratory-occlusion maneuver predicted fluid responsiveness with sensitivity of 64% (95% CI 44% to 81%) and specificity of 77% (95% CI 55% to 92%). The area under the receiver operating curve generated for changes in velocity time integral was significantly higher than the one generated for changes in peak velocity (0.96 ± 0.03 versus 0.70 ± 0.07, respectively, P = 0.0004 for both). The gray zone ranged between 6 and 10% (20% of the patients) for changes in velocity time integral and between 1 and 13% (62% of the patients) for changes in peak velocity. CONCLUSIONS: In mechanically ventilated and sedated patients in the neuro Intensive Care Unit, changes in velocity time integral during a 12-sec end-expiratory-occlusion maneuver were able to predict fluid responsiveness and perform better than changes in peak velocity.