Testing preload responsiveness by the tidal volume challenge assessed by the photoplethysmographic perfusion index.

BACKGROUND: To detect preload responsiveness in patients ventilated with a tidal volume (Vt) at 6 mL/kg of predicted body weight (PBW), the Vt-challenge consists in increasing Vt from 6 to 8 mL/kg PBW and measuring the increase in pulse pressure variation (PPV). However, this requires an arterial catheter. The perfusion index (PI), which reflects the amplitude of the photoplethysmographic signal, may reflect stroke volume and its respiratory variation (pleth variability index, PVI) may estimate PPV. We assessed whether Vt-challenge-induced changes in PI or PVI could be as reliable as changes in PPV for detecting preload responsiveness defined by a PLR-induced increase in cardiac index (CI) ≥ 10%. METHODS: In critically ill patients ventilated with Vt = 6 mL/kg PBW and no spontaneous breathing, haemodynamic (PICCO2 system) and photoplethysmographic (Masimo-SET technique, sensor placed on the finger or the forehead) data were recorded during a Vt-challenge and a PLR test. RESULTS: Among 63 screened patients, 21 (33%) were excluded because of an unstable PI signal and/or atrial fibrillation and 42 were included. During the Vt-challenge in the 16 preload responders, CI decreased by 4.8 ± 2.8% (percent change), PPV increased by 4.4 ± 1.9% (absolute change), PIfinger decreased by 14.5 ± 10.7% (percent change), PVIfinger increased by 1.9 ± 2.6% (absolute change), PIforehead decreased by 18.7 ± 10.9 (percent change) and PVIforehead increased by 1.0 ± 2.5 (absolute change). All these changes were larger than in preload non-responders. The area under the ROC curve (AUROC) for detecting preload responsiveness was 0.97 ± 0.02 for the Vt-challenge-induced changes in CI (percent change), 0.95 ± 0.04 for the Vt-challenge-induced changes in PPV (absolute change), 0.98 ± 0.02 for Vt-challenge-induced changes in PIforehead (percent change) and 0.85 ± 0.05 for Vt-challenge-induced changes in PIfinger (percent change) (p = 0.04 vs. PIforehead). The AUROC for the Vt-challenge-induced changes in PVIforehead and PVIfinger was significantly larger than 0.50, but smaller than the AUROC for the Vt-challenge-induced changes in PPV. CONCLUSIONS: In patients under mechanical ventilation with no spontaneous breathing and/or atrial fibrillation, changes in PI detected during Vt-challenge reliably detected preload responsiveness. The reliability was better when PI was measured on the forehead than on the fingertip. Changes in PVI during the Vt-challenge also detected preload responsiveness, but with lower accuracy.

Peripheral perfusion index of pulse oximetry in adult patients: a narrative review.

The peripheral perfusion index (PI) is derived from pulse oximetry and is defined as the ratio of the pulse wave of the pulsatile portion (arteries) to the non-pulsatile portion (venous and other tissues). A growing number of clinical studies have supported the use of PI in various clinical scenarios, such as guiding hemodynamic management and serving as an indicator of outcome and organ function. In this review, we will introduce and discuss this traditional but neglected indicator of the peripheral microcirculatory perfusion. Further clinical trials are required to clarify the normal and critical values of PI for different monitoring devices in various clinical conditions, to establish different standards of PI-guided strategies, and to determine the effect of PI-guided therapy on outcome.

Correlation of Block Success with Perfusion Index Measurement in Cases of Pediatric Surgery Under Caudal Epidural Block Anesthesia.

PURPOSE: One of the regional anesthetic procedures, caudal epidural block, is important for lower extremities surgeries in the pediatric patient population. The perfusion index (PI) value, which reflects vasomotor tone, can be used to indicate block success. The aim was to compare the role of perfusion index, heart rate, and mean arterial pressure in detecting the success of caudal epidural block and to investigate whether perfusion index was an earlier indicator in determining the success of the block in pediatric surgery cases. DESIGN: A randomized controlled trial. METHODS: The study included 58 patients, American Society of Anesthesiologists'classification 1, between the ages 1 and 6 years. In the left lateral decubitus posture, caudal epidural block was performed using a 23 or 25-gauge caudal needle and a dosage of 0.25% bupivacaine (1 mL/kg). At the 0, 1, 5, 7, 10, 15, and 20th minutes, peripheral oxygen saturation, heart rate, mean arterial pressure, and PI values were obtained using a probe attached to the first toe of the left foot. A successful caudal epidural block indication was defined as an increase of at least 100% in the PI value over the baseline value and a 15% decrease in mean arterial pressure and heart rate FINDINGS: PI represents the ratio of the photoplethysmography signal to pulsatile over nonpulsatile light absorbance. An increase in the PI value indicates that the block is effective. In the 20-minute follow-up period after caudal epidural block, there was at least a 100% increase in PI value in all of the patients at the seventh minute. An expected 15% reduction in mean arterial pressure was observed in 14.5% of the patients and an expected 15% reduction in heart rate was observed in 45.6% of the patients. CONCLUSIONS: The results obtained from our study show that the increase in PI values is associated with caudal epidural block success. The PI value is more rapid, sensitive and objective than those produced by other parameters. Benefits include an earlier change in anesthesia management due to block failure and faster initiation to surgery, which reduces exposure to anesthetic chemicals.

The Effects of Rso2 and PI Monitoring Images on the Treatment of Premature Infants Based on Deep Learning.

In recent years, due to the combined effects of individual behavior, psychological factors, environmental exposure, medical conditions, biological factors, etc., the incidence of preterm birth has gradually increased, so the incidence of various complications of preterm infants has also become higher and higher. This article is aimed at studying the therapeutic effects of preterm infants and proposing the application of rSO2 and PI image monitoring based on deep learning to the treatment of preterm infants. This article introduces deep learning, blood perfusion index, preterm infants, and other related content in detail and conducts experiments on the treatment of rSO2 and PI monitoring images based on deep learning in preterm infants. The experimental results show that the rSO2 and PI monitoring images based on deep learning can provide great help for the treatment of preterm infants and greatly improve the treatment efficiency of preterm infants by at least 15%.

The use of oxygen reserve index in one-lung ventilation and its impact on peripheral oxygen saturation, perfusion index and, pleth variability index.

BACKGROUND: Our goal is to investigate the use of the oxygen reserve index (ORi) to detect hypoxemia and its relation with parameters such as; peripheral oxygen saturation, perfusion index (PI), and pleth variability index (PVI) during one-lung ventilation (OLV). METHODS: Fifty patients undergoing general anesthesia and OLV for elective thoracic surgeries were enrolled in an observational cohort study in a tertiary care teaching hospital. All patients required OLV after a left-sided double-lumen tube insertion during intubation. The definition of hypoxemia during OLV is a peripheral oxygen saturation (SpO2) value of less than 95%, while the inspired oxygen fraction (FiO2) is higher than 50% on a pulse oximetry device. ORi, pulse oximetry, PI, and PVI values were measured continuously. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and accuracy were calculated for ORi values equal to zero in different time points during surgery to predict hypoxemia. At Clinicaltrials.gov registry, the Registration ID is NCT05050552. RESULTS: Hypoxemia was observed in 19 patients (38%). The accuracy for predicting hypoxemia during anesthesia induction at ORi value equals zero at 5 min after intubation in the supine position (DS5) showed a sensitivity of 92.3% (95% CI 84.9-99.6), specificity of 81.1% (95% CI 70.2-91.9), and an accuracy of 84.0% (95% CI 73.8-94.2). For predicting hypoxemia, ORi equals zero show good sensitivity, specificity, and statistical accuracy values for time points of DS5 until OLV30 where the sensitivity of 43.8%, specificity of 64%, and an accuracy of 56.1% were recorded. ORi and SpO2 correlation was found at DS5, 5 min after lateral position with two-lung ventilation (DL5) and at 10 min after OLV (OLV10) (p = 0.044, p = 0.039, p = 0.011, respectively). Time-dependent correlations also showed that; at a time point of DS5, ORi has a significant negative correlation with PI whereas, no correlations with PVI were noted. CONCLUSIONS: During the use of OLV for thoracic surgeries, from 5 min after intubation (DS5) up to 30 min after the start of OLV, ORi provides valuable information in predicting hypoxemia defined as SpO2 less than 95% on pulse oximeter at FiO2 higher than 50%.

Sulfato de magnesio como ahorrador de opioides en cirugía mayor abdominal / Magnesium sulfate as an opioid sparer in major abdominal surgery

Introducción: El efecto del sulfato de magnesio como adyuvante de la analgesia en la práctica de diferentes intervenciones quirúrgicas es un tema en debate y estudio constante con el fin de probar su eficacia y seguridad en la mejora de la evolución posoperatoria de los pacientes. Objetivo: Evaluar la efectividad y seguridad del sulfato de magnesio como ahorrador de opioides en la anestesia general de pacientes intervenidos por cirugía mayor abdominal. Métodos: Estudio cuasiexperimental, prospectivo, longitudinal realizado en 44 pacientes del Hospital Universitario "General Calixto García", desde diciembre de 2019 hasta diciembre de 2020. Se crearon dos grupos, un grupo estudio (sulfato de magnesio) y otro control. Se evaluó la analgesia intraoperatoria y posoperatoria, el consumo intraoperatorio de fentanil, la necesidad de analgesia de rescate y las complicaciones perioperatorias. Resultados: En los pacientes que se les administró el sulfato de magnesio la tensión arterial media, la frecuencia cardiaca y el índice de shock tuvieron una tendencia a mantenerse por debajo de la media global. El índice de perfusión aumentó y se mantuvo con esa tendencia y tuvieron un menor consumo de fentanil. Conclusiones: La administración de sulfato de magnesio como adyuvante de la anestesia general en pacientes intervenidos por cirugía abdominal mayor electiva, resultó efectiva y segura, pues brindó mayor analgesia perioperatoria, estabilidad hemodinámica, menor consumo de opioides intraoperatorio y menor rescate analgésico posoperatorio que cuando no se usó. La incidencia de complicaciones fue baja y sin repercusión clínica(AU)

Introduction: The effect of magnesium sulfate as an adjunct to analgesia during different surgical interventions is a subject under constant debate and study, with respect to showing its efficacy and safety in improving the postoperative evolution of patients. Objective: To assess the effectiveness and safety of magnesium sulfate as an opioid sparer in general anesthesia with patients undergoing major abdominal surgery. Methods: Quasiexperimental, prospective and longitudinal study carried out, from December 2019 to December 2020, with 44 patients from General Calixto García University Hospital. Two groups were created: a study group (magnesium sulfate) and a control group. Intraoperative and postoperative analgesia, intraoperative fentanyl consumption, requirement of salvage analgesia, as well as perioperative complications were evaluated. Results: In the patients who were administered magnesium sulfate, mean arterial pressure, heart rate and shock index tended to remain below the global mean. The perfusion index increased and maintained this trend, while they had a lower consumption of fentanyl. Conclusions: The administration of magnesium sulfate as an adjunct to general anesthesia in patients undergoing major elective abdominal surgery was effective and safe, as it provided greater perioperative analgesia, hemodynamic stability, less intraoperative opioid consumption and less postoperative analgesic rescue than in the control group. The incidence of complications was low and without clinical repercussions(AU)

Intertwin differences in umbilical artery pulsatility index are associated with infant survival in twin-to-twin transfusion syndrome.

OBJECTIVES: To evaluate the association of intertwin differences in umbilical artery pulsatility index (DUAPI) and infant survival in twin-to-twin transfusion syndrome (TTTS). METHODS: Absolute DUAPI was calculated prior to laser surgery. Receiver-operating characteristics (ROC) curve analysis provided an intertwin DUAPI cutoff of 0.4 for the prediction of double twin survival to 30 days of life. Infant survival was compared between women with an intertwin DUAPI <0.4 and ≥0.4 in the whole cohort, in TTTS cases with Quintero stages I/II and in those with Quintero stages III/IV. Regression analyses were performed to evaluate the association of intertwin DUAPI <0.4 and infant survival adjusted for confounders. RESULTS: In total, 349 TTTS cases were included. Double twin survival to 30 days was observed in 67% (234/349) of cases. Significant differences in double twin survival was seen between intertwin DUAPI groups in the whole cohort (76.8 vs. 52.2%; p<0.001), in women with TTTS Quintero stage I or II (77.8 vs. 58.5%; p=0.015) as well as in women with TTTS Quintero stage III or IV (75 vs. 49.5%; p=0.001). Intertwin DUAPI <0.4 conferred a threefold increased chance for double twin survival. CONCLUSIONS: Small intertwin DUAPI is associated with increased double infant survival in early and advanced TTTS stages.

Decreased peripheral perfusion measured by perfusion index is a novel indicator for cardiovascular death in patients with type 2 diabetes and established cardiovascular disease.

Cardiovascular disease (CVD) is still the major cause of mortality in patients with type 2 diabetes. Despite of recent therapies, mortality and resources spent on healthcare due to CVD is still important problem. Thus, appropriate markers are needed to predict poor outcomes. Therefore, we investigated the role of peripheral perfusion as an indicator for cardiovascular death in patients with type 2 diabetes and established CVD. This retrospective cohort study included 1080 patients with type 2 diabetes and history of CVD recruited from the outpatient clinic at Matsushita Memorial Hospital in Osaka, Japan. Peripheral perfusion is assessed using the perfusion index (PI), which represents the level of circulation through peripheral tissues. The median age and PI values were 74 years (range: 67-79 years) and 2.6% (range: 1.1-4.3%), respectively. During follow-up duration, 60 patients died due to CVD. The adjusted Cox regression analysis demonstrated that the risk of developing cardiovascular death was higher in the first quartile (Hazard ratio, 6.23; 95% CI, 2.28 to 22.12) or second quartile (Hazard ratio, 3.04; 95% CI, 1.46 to 6.85) of PI than that in the highest quartile (fourth quartile) of PI. PI (per 1% decrease) was associated with the development of cardiovascular death (Hazard ratio, 1.39; 95% CI, 1.16 to 1.68). PI could be a novel indicator of cardiovascular death in patients with type 2 diabetes and established CVD.

Changes in the Plethysmographic Perfusion Index During an End-Expiratory Occlusion Detect a Positive Passive Leg Raising Test.

OBJECTIVES: The end-expiratory occlusion test for assessing preload responsiveness consists in interrupting mechanical ventilation for 15 seconds at end-expiration and measuring the cardiac index changes. The perfusion index is the ratio between the pulsatile and the nonpulsatile portions of the plethysmography signal and is, in part, determined by stroke volume. We tested whether the end-expiratory occlusion-induced changes in perfusion index could detect a positive passive leg raising test, suggesting preload responsiveness. DESIGN: Observational study. SETTING: Medical ICU. PATIENTS: Thirty-one ventilated patients without atrial fibrillation. INTERVENTIONS: We measured perfusion index (Radical-7 device; Masimo Corp., Irvine, CA) and cardiac index (PiCCO2; Pulsion Medical Systems, Feldkirchen, Germany) before and during a passive leg raising test and a 15-second end-expiratory occlusion. MEASUREMENTS AND MAIN RESULTS: In 19 patients with a positive passive leg raising test (increase in cardiac index ≥ 10%), compared to the baseline value and expressed as a relative change, passive leg raising increased cardiac index and perfusion index by 17% ± 7% and 49% ± 23%, respectively, In these patients, end-expiratory occlusion increased cardiac index and perfusion index by 6% ± 2% and 11% ± 8%, respectively. In the 12 patients with a negative passive leg raising test, perfusion index did not significantly change during passive leg raising and end-expiratory occlusion. Relative changes in perfusion index and cardiac index observed during all interventions were significantly correlated (r = 0.83). An end-expiratory occlusion-induced relative increase in perfusion index greater than or equal to 2.5% ([perfusion index during end-expiratory occlusion-perfusion index at baseline]/perfusion index at baseline × 100) detected a positive passive leg raising test with an area under the receiver operating characteristic curve of 0.95 ± 0.03. This threshold is larger than the least significant change observed for perfusion index (1.62% ± 0.80%). CONCLUSIONS: Perfusion index could be used as a reliable surrogate of cardiac index for performing the end-expiratory occlusion test. Confirming previous results, the relative changes in perfusion index also reliably detected a positive passive leg raising test.

Prediction of Shock by Peripheral Perfusion Index.

OBJECTIVE: To detect occurrence of clinical shock and impending shock by monitoring Peripheral Perfusion Index (PI). METHODS: In this study, 100 children aged 1 mo to 12 y of age who needed hemodynamic monitoring were included and categorized into five age groups. Demographic data, nutritional status, vital parameters, perfusion index and laboratory parameters were recorded. Hemodynamic monitoring was done for 48 h. In total, 65 and 35 children were admitted with and without features of shock respectively. Nine hundred thirty six hemodynamic measurements were taken and analyzed. Correlation between perfusion index, blood pressures and clinically assessed shock were done. RESULTS: Clinical shock can be reasonably detected when perfusion index value is less than 1.15 in children less than 3 y of age, less than 1.25 in 3 to 10 y of age and less than 1.55 in 10 to 12 y of age. These values had high sensitivity and low false positivity in detecting clinically assessed shock in that particular age group. PI had good correlation with pulse pressure and systolic blood pressure in all age groups and weak correlation with mean arterial blood pressure and diastolic blood pressure. A 57% reduction in PI value from the baseline value may predict impending shock in children. CONCLUSION: Perfusion index can be used as a non-invasive, continuous parameter to monitor peripheral perfusion in children and to detect impending shock.

Base Excess usefulness for prediction of immediate mortality in severe trauma patients admitted to the Emergency department.

BACKGROUND: Trauma is a leading cause of death in young people and hemorrhagic shock is a leading mechanism of this mortality. Hypoperfusion can be difficult to diagnose clinically, especially in younger patients. Arterial Base Excess (BE) has been used as an early indicator of hypoperfusion. AIM: To evaluate the prognostic value of admission BE in severe trauma patients admitted to the emergency department (ED). METHODS: In this prospective study, severe trauma patients meeting high velocity criteria admitted to the ED during the study period were included. BE was calculated from arterial blood gas samples. Multivariate analysis was performed for Day-1 and Day-7 post trauma mortality. ROC characteristics and survival curves were used. RESULTS: We included 479 patients. Median age was 37 (18-90). Eighty-one per cent were male. Clinical characteristics n(%): GCS<13: 170(35); SBP<90 mmHg: 64(13) and SpO2 <90%: 82(17). Mean ISS was 22 ± 13. Mortality was at days 1 and 7: 2.2% and 27.3%, respectively. Median BE was -3.2 mmol/l (-25; 28). Forty-five per cent had a BE ≤ -3.5 mmol/l. In multivariate analysis, initial BE ≤ -6.5 mmol/l was predictive of first day mortality with an Odds Ratio; [CI95%] = 3.17; [1.4-7.1]; p=0.005. Similar results were found at Day 7: Odds Ratio; [CI95%] = 1.5; [1.14-1.96]; p=0.003. BE showed high prognostic value for both mortality rates. Survival curve was significant for BE> -6.5mmol/l. CONCLUSION: in this study, a high BE above 6.5mmol/L showed a significant prognostic value in immediate and early mortality and is proposed as a marker of injury severity in trauma patients admitted to the ED. Prediction was better for the immediate mortality and thus could be proposed as a triage tool in the ED.