Noninvasive Assessment of Arterial Pulse-Pressure Variation During General Anesthesia: Clinical Evaluation of a New High-Fidelity Upper Arm Cuff.

OBJECTIVES: To compare noninvasive pulse-pressure variation (PPV) measurements obtained from a new high-fidelity upper arm cuff using a hydraulic coupling technique to corresponding intraarterial PPV measurements. DESIGN: The authors used prospective multicenter comparison and development studies for the new high-fidelity upper arm cuff. SETTING: The study was performed in the departments of Anesthesiology at the Ludwig-Maximilians-Universität München Hospital, the University Hospital of Bonn, and the RoMed Hospital in Rosenheim (all Germany). PARTICIPANTS: A total of 153 patients were enrolled, undergoing major abdominal surgery or neurosurgery with mechanical ventilation. For the evaluation of PPV, 1,467 paired measurements in 107 patients were available after exclusion due to predefined quality criteria. INTERVENTIONS: Simultaneous measurements of PPV were performed from a reference femoral arterial catheter (PPVref) and the high-fidelity upper arm cuff (PPVcuff). The new device uses a semirigid conical shell. It incorporates a hydraulic sensor pad with a pressure transducer, leading to a tissue pressure-pulse contour with all characteristics of an arterial- pulse contour. MEASUREMENTS AND MAIN RESULTS: The comparative analysis of the included measurements showed that PPVref and PPVcuff were closely correlated (r = 0.92). The mean of the differences between PPVref and PPVcuff was 0.1 ± 2.0%, with 95% limits of agreement between -4.1% and 3.9%. To track absolute changes in PPV >2%, the concordance rate between the 2 methods was 93%. CONCLUSIONS: The new high-fidelity upper arm cuff method provided a clinically reliable estimate of PPV.

Clinical Evaluation of a High-fidelity Upper Arm Cuff to Measure Arterial Blood Pressure during Noncardiac Surgery.

BACKGROUND: In most patients having noncardiac surgery, blood pressure is measured with the oscillometric upper arm cuff method. Although the method is noninvasive and practical, it is known to overestimate intraarterial pressure in hypotension and to underestimate it in hypertension. A high-fidelity upper arm cuff incorporating a hydraulic sensor pad was recently developed. The aim of the present study was to investigate whether noninvasive blood pressure measurements with the new high-fidelity cuff correspond to invasive measurements with a femoral artery catheter, especially at low blood pressure. METHODS: Simultaneous measurements of blood pressure recorded from a femoral arterial catheter and from the high-fidelity upper arm cuff were compared in 110 patients having major abdominal surgery or neurosurgery. RESULTS: 550 pairs of blood pressure measurements (5 pairs per patient) were considered for analysis. For mean arterial pressure measurements, the average bias was 0 mmHg, and the precision was 3 mmHg. The Pearson correlation coefficient was 0.96 (P < 0.0001; 95% CI, 0.96 to 0.97), and the percentage error was 9%. Error grid analysis showed that the proportions of mean arterial pressure measurements done with the high-fidelity cuff method were 98.4% in zone A (no risk), 1.6% in zone B (low risk) and 0% in zones C, D, and E (moderate, significant, and dangerous risk, respectively). The high-fidelity cuff method detected mean arterial pressure values less than 65 mmHg with a sensitivity of 84% (95% CI, 74 to 92%) and a specificity of 97% (95% CI, 95% to 98%). To detect changes in mean arterial pressure of more than 5 mmHg, the concordance rate between the two methods was 99.7%. Comparable accuracy and precision were observed for systolic and diastolic blood pressure measurements. CONCLUSIONS: The new high-fidelity upper arm cuff method met the current international standards in terms of accuracy and precision. It was also very accurate to track changes in blood pressure and reliably detect severe hypotension during noncardiac surgery.

CT Findings in Negative Pressure Pulmonary Edema.

Negative pressure pulmonary edema (NPPE) is a rare, potentially life-threatening, and yet diagnostically challenging perioperative complication. Most cases of NPPE occur in the context of anesthetic procedures, mainly caused by upper airway obstruction, and are diagnosed during the recovery period. We present a case of fulminant NPPE in a patient during general anesthesia which illustrates the eye-catching CT findings that can occur in NPPE and eventually support diagnosis. With regard to the current pandemic, we include a discussion of the typical imaging patterns of COVID-19 as a radiological differential diagnosis of NPPE. A 42-year old male patient presented with sudden respiratory insufficiency during arthroscopic knee lavage and subsequently required highly invasive ventilation therapy and catecholamine administration. Postoperative CT imaging of the thorax exhibited extensive, centrally accentuated consolidations with surrounding ground-glass opacity in all lung lobes, suggestive of pulmonary edema. In view of the clinical course and the imaging findings, a negative pressure pulmonary edema (NPPE) was diagnosed.