Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2020
Do changes in perfusion index reflect changes in stroke volume during preload-modifying manoeuvres?
Changes in stroke volume (deltaSV) induced by a lung recruitment manoeuvre (LRM) have been shown to accurately predict fluid responsiveness during protective mechanical ventilation. Cardiac output monitors are used in a limited number of surgical patients. In contrast, all patients are monitored with a pulse oximeter, that may enable the continuous monitoring of a peripheral perfusion index (PI). ⋯ A deltaPI ≥ 26% predicted a deltaSV > 30% with a sensitivity of 83% and a specificity of 78% (AUC = 0.84, 95%CI 0.71-0.93). 24 patients experienced a deltaSV > 30% and subsequently received fluid. Fluid loads induced a 16% increase in SV and a 17% increase in PI, but fluid-induced deltaPI and deltaSV were weakly correlated (r2 = 0.19). In neurosurgical patients, we conclude that deltaPI may be used as a surrogate for deltaSV during LRMs but not during fluid loading.
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J Clin Monit Comput · Dec 2020
Validation of an automated system for detecting ineffective triggering asynchronies during mechanical ventilation: a retrospective study.
We compare the sensitivity and specificity of clinician visual waveform analysis against an automated system's waveform analysis in detecting ineffective triggering in mechanically ventilated intensive care unit patients when compared against a reference label set based upon analysis of respiratory muscle activity. Electrical activity of the diaphragm or esophageal/transdiaphragmatic pressure waveforms were available to a single clinician for the generation of a reference label set indicating the ground truth, that is, presence or absence of ineffective triggering, on a breath-by-breath basis. Pressure and flow versus time tracings were made available to (i) a group of three clinicians; and (ii) the automated Syncron-E™ system capable of detecting patient-ventilator asynchrony in real-time, in order to obtain breath-by-breath labels indicating the presence or absence of ineffective triggering. ⋯ Specificity for clinicians and the automated system were high (99.3% for clinician and 98.5% for the automated system). The automated system had a significantly higher sensitivity (83.2%) compared to clinicians (41.1%). Ineffective triggering detected by the automated system, which has access only to airway pressure and flow versus time tracings, is in substantial agreement with a reference detection derived from analysis of invasively measured patient effort waveforms.
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J Clin Monit Comput · Dec 2020
Comment LetterThe artificial count of artifacts for thoracic ultrasound: what is the clinical usefulness?
Many works in the literature have shown that the increase in the number of B lines is a nonspecific sign of underlying pulmonary disease. Actually these artifacts are the result of a physical effect of ultrasound between the chest wall and the pulmonary air. Nevertheless the intra- and inter-operator variability in B-lines counting does not only reside only in the count itself but depends also on the type and frequency of the probe used, as well as the ultrasound scan machine setting and the patient's chest shape. In our opinion, proposing a software algorithm to count lines B seems like an unproductive effort.
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J Clin Monit Comput · Dec 2020
The Peripheral Perfusion Index tracks systemic haemodynamics during general anaesthesia.
Stable intraoperative haemodynamics are associated with improved outcome and even short periods of instability are associated with an increased risk of complications. During anaesthesia intermittent non-invasive blood pressure and heart rate remains the cornerstone of haemodynamic monitoring. Continuous monitoring of systemic blood pressure or even -flow requires invasive or advanced modalities creating a barrier for obtaining important real-time haemodynamic insight. ⋯ After stabilizing a second HUT decreased PPI 59% (49-76), SV 33% (28-37), CO 31% (28-36), and MAP 34% (26-38). Restoration of preload with PE increased PPI by 607% (218-1078), SV by 96% (82-116), CO by 65% (56-99), and MAP by 114% (83-147). During general anaesthesia changes in PPI tracked changes in systemic haemodynamics.
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J Clin Monit Comput · Dec 2020
Observational StudyThe ability of perfusion index to detect segmental ulnar nerve sparing after supraclavicular nerve block.
Supraclavicular nerve block (SCB) is a commonly used regional block for upper extremity surgery. The most common form of failure of SCB is ulnar segmental sparing. We aimed to evaluate the accuracy of perfusion index (PI) in early detection of segmental sparing of the ulnar component of SCB. ⋯ An increase of 71% in PI at the little finger 5 min after SCB could accurately rule out ulnar sparing. Clinical trial identifier NCT03880201. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT03880201?term=NCT03880201&draw=2&rank=1 .