Association between peripheral perfusion index and postoperative acute kidney injury in major noncardiac surgery patients receiving continuous vasopressors: a post hoc exploratory analysis of the VEGA-1 trial.

BACKGROUND: The peripheral perfusion index is the ratio of pulsatile to nonpulsatile static blood flow obtained by photoplethysmography and reflects peripheral tissue perfusion. We investigated the association between intraoperative perfusion index and postoperative acute kidney injury in patients undergoing major noncardiac surgery and receiving continuous vasopressor infusions. METHODS: In this exploratory post hoc analysis of a pragmatic, cluster-randomised, multicentre trial, we obtained areas and cumulative times under various thresholds of perfusion index and investigated their association with acute kidney injury in multivariable logistic regression analyses. In secondary analyses, we investigated the association of time-weighted average perfusion index with acute kidney injury. The 30-day mortality was a secondary outcome. RESULTS: Of 2534 cases included, 8.9% developed postoperative acute kidney injury. Areas and cumulative times under a perfusion index of 3% and 2% were associated with an increased risk of acute kidney injury; the strongest association was observed for area under a perfusion index of 1% (adjusted odds ratio [aOR] 1.32, 95% confidence interval [CI] 1.00-1.74, P=0.050, per 100%∗min increase). Additionally, time-weighted average perfusion index was associated with acute kidney injury (aOR 0.82, 95% CI 0.74-0.91, P<0.001) and 30-day mortality (aOR 0.68, 95% CI 0.49-0.95, P=0.024). CONCLUSIONS: Larger areas and longer cumulative times under thresholds of perfusion index and lower time-weighted average perfusion index were associated with postoperative acute kidney injury in patients undergoing major noncardiac surgery and receiving continuous vasopressor infusions. CLINICAL TRIAL REGISTRATION: NCT04789330.

Prospective Evaluation of the Peripheral Perfusion Index in Assessing the Organ Dysfunction and Prognosis of Adult Patients With Sepsis in the ICU.

Background: The peripheral perfusion index (PI) reflects microcirculatory blood flow perfusion and indicates the severity and prognosis of sepsis. Method: The cohort comprised 208 patients admitted to the intensive care unit (ICU) with infection, among which 117 had sepsis. Demographics, medication history, ICU variables, and laboratory indexes were collected. Primary endpoints were in-hospital mortality and 28-day mortality. Secondary endpoints included organ function variables (coagulation function, liver function, renal function, and myocardial injury), lactate concentration, mechanical ventilation time, and length of ICU stay. Univariate and multivariate analyses were conducted to assess the associations between the PI and clinical outcomes. Sensitivity analyses were performed to explore the associations between the PI and organ functions in the sepsis and nonsepsis groups. Result: The PI was negatively associated with in-hospital mortality (odds ratio [OR] 0.29, 95% confidence interval [CI] 0.15 to 0.55), but was not associated with 28-day mortality. The PI was negatively associated with the coagulation markers prothrombin time (PT) (ß -0.36, 95% CI -0.59 to 0.13) and activated partial thromboplastin time (APTT) (ß -1.08, 95% CI -1.86 to 0.31), and the myocardial injury marker cardiac troponin I (cTnI) (ß -2085.48, 95% CI -3892.35 to 278.61) in univariate analysis, and with the PT (ß -0.36, 95% CI -0.60 to 0.13) in multivariate analysis. The PI was negatively associated with the lactate concentration (ß -0.57, 95% CI -0.95 to 0.19), mechanical ventilation time (ß -23.11, 95% CI -36.54 to 9.69), and length of ICU stay (ß -1.28, 95% CI -2.01 to 0.55). Sensitivity analyses showed that the PI was significantly associated with coagulation markers (PT and APTT) and a myocardial injury marker (cTnI) in patients with sepsis, suggesting that the associations between the PI and organ function were stronger in the sepsis group than the nonsepsis group. Conclusion: The PI provides new insights for assessing the disease severity, short-term prognosis, and organ function damage in ICU patients with sepsis, laying a theoretical foundation for future research.

The level of partial pressure of carbon dioxide affects organ perfusion in respiratory failure patients undergoing pressure support ventilation with venovenous extracorporeal membrane oxygenation: a prospective study.

BACKGROUND: We evaluated the influence of different partial carbon dioxide pressure (PaCO2) levels on organ perfusion in patients with respiratory failure receiving pressure-support ventilation with veno-venous extracorporeal membrane oxygenation (V-V ECMO). METHODS: In this twelve patients prospective study, ECMO gas-flow was decreased from baseline (PaCO2 < 40 mmHg) until PaCO2 increased by 5-10 mmHg (High-CO2 phase). Resistance indices of gut, spleen, and snuffbox artery, the peripheral perfusion index (PPI), and heart rate variability were measured at baseline and High-CO2 phase. RESULTS: When PaCO2 increased from 36 (36-37) mmHg at baseline to 42 (41-43) mmHg in the High-CO2 phase (p < 0.001), PPI decreased significantly (p = 0.026). The snuffbox artery (p = 0.022), superior mesenteric artery (p = 0.042), and spleen (p = 0.012) resistance indices increased significantly. The root mean square of successive differences (RMSSD) decreased from 19.5(18.1-22.7) to 15.9(14.4-18.6) ms (p = 0.034), and the ratio of low-frequency to high-frequency components(LF/HF) increased from 0.47 ± 0.23 to 0.70 ± 0.38 (p = 0.013). CONCLUSIONS: High PaCO2 might cause decreased peripheral tissue and visceral organ perfusion through autonomic nervous system in patients with respiratory failure undergoing PSV with V-V ECMO.

Prediction of preload dependency using phenylephrine-induced peripheral perfusion index during general anaesthesia: a prospective observational study.

BACKGROUND: Tracking preload dependency non-invasively to maintain adequate tissue perfusion in the perioperative period can be challenging.The effect of phenylephrine on stroke volume is dependent upon preload. Changes in stroke volume induced by phenylephrine administration can be used to predict preload dependency. The change in the peripheral perfusion index derived from photoplethysmography signals reportedly corresponds with changes in stroke volume in situations such as body position changes in the operating room. Thus, the peripheral perfusion index can be used as a non-invasive potential alternative to stroke volume to predict preload dependency. Herein, we aimed to determine whether changes in perfusion index induced by the administration of phenylephrine could be used to predict preload dependency. METHODS: We conducted a prospective single-centre observational study. The haemodynamic parameters and perfusion index were recorded before and 1 and 2 min after administering 0.1 mg of phenylephrine during post-induction hypotension in patients scheduled to undergo surgery. Preload dependency was defined as a stroke volume variation of ≥ 12% before phenylephrine administration at a mean arterial pressure of < 65 mmHg. Patients were divided into four groups according to total peripheral resistance and preload dependency. RESULTS: Forty-two patients were included in this study. The stroke volume in patients with preload dependency (n = 23) increased after phenylephrine administration. However, phenylephrine administration did not impact the stroke volume in patients without preload dependency (n = 19). The perfusion index decreased regardless of preload dependency. The changes in the perfusion index after phenylephrine administration exhibited low accuracy for predicting preload dependency. Based on subgroup analysis, patients with high total peripheral resistance tended to exhibit increased stroke volume following phenylephrine administration, which was particularly prominent in patients with high total peripheral resistance and preload dependency. CONCLUSION: The findings of the current study revealed that changes in the perfusion index induced by administering 0.1 mg of phenylephrine could not predict preload dependency. This may be attributed to the different phenylephrine-induced stroke volume patterns observed in patients according to the degree of total peripheral resistance and preload dependency. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN000049994 on 9/01/2023).

Peripheral perfusion index as a predictor of reintubation in critically ill surgical patients.

PURPOSE: We aimed to evaluate the ability of the peripheral perfusion index (PPI) to predict reintubation of critically ill surgical patients. METHODS: This prospective observational study included mechanically ventilated adults who were extubated after a successful spontaneous breathing trial (SBT). The patients were followed up for the next 48 h for the need for reintubation. The heart rate, systolic blood pressure, respiratory rate, peripheral arterial oxygen saturation (SpO2), and PPI were measured before-, at the end of SBT, 1 and 2 h postextubation. The primary outcome was the ability of PPI 1 h postextubation to predict reintubation using area under the receiver operating characteristic curve (AUC) analysis. Univariate and multivariate analyses were performed to identify predictors for reintubation. RESULTS: Data from 62 patients were analysed. Reintubation occurred in 12/62 (19%) of the patients. Reintubated patients had higher heart rate and respiratory rate; and lower SpO2 and PPI than successfully weaned patients. The AUC (95%confidence interval) for the ability of PPI at 1 h postextubation to predict reintubation was 0.82 (0.71-0.91) with a negative predictive value of 97%, at a cutoff value of ≤ 2.5. Low PPI and high respiratory rate were the independent predictors for reintubation. CONCLUSION: PPI early after extubation is a useful tool for prediction of reintubation. Low PPI is an independent risk factor for reintubation. A PPI > 2.5, one hour after extubation can confirm successful extubation.

The use of thermal imaging for evaluation of peripheral tissue perfusion in surgical patients with septic shock.

BACKGROUND: In this study, we aimed to evaluate the ability of central-to-peripheral temperature gradients using thermal imaging to predict in-hospital mortality in surgical patients with septic shock. METHODS: This prospective observational study included adult patients with septic shock admitted to the intensive care unit postoperatively. Serum lactate (in mmol/L), capillary refill time (CRT) (in seconds), toe (peripheral) and canthal (central) temperature by infrared thermography and the corresponding room temperature in (Celsius [°C]) were assessed at the time of admission, 6- and 12 h after admission. The canthal-toe and room-toe temperature gradients were calculated. According to their final outcomes, patients were divided into survivors and non-survivors. The ability of canthal-toe temperature gradient (primary outcome), room-toe temperature gradient, toe temperature, serum lactate and CRT, measured at the prespecified timepoints to predict in-hospital mortality was analyzed using the area under receiver operating characteristic curve (AUC). RESULTS: Fifty-six patients were included and were available for the final analysis and 41/56 (73%) patients died. The canthal-toe and room-toe temperature gradients did not show significant accuracy in predicting mortality at any timepoint. Only the toe temperature measurement at 12 h showed good ability in predicting in-hospital mortality with AUC (95% confidence interval) of 0.72 (0.58-0.84) and a negative predictive value of 70% at toe temperature of ≤ 25.5 °C. Both serum lactate and CRT showed good ability to predict in-hospital mortality at all timepoints with high positive predictive values (> 90%) at cut-off value of > 2.5-4.3 mmol/L for the serum lactate and > 3-4.2 s for the CRT. CONCLUSION: In post-operative emergency surgical patients with septic shock, high serum lactate and CRT can accurately predict in-hospital mortality and were superior to thermal imaging, especially in the positive predictive values. Toe temperature > 25.5 °C, measured using infrared thermal imaging can exclude in-hospital mortality with a negative predictive value of 70%.

Racial effects on masimo pulse oximetry: impact of low perfusion index.

PURPOSE:  Evaluate the SpO2-SaO2 difference between Black and White volunteer subjects having a low perfusion index (Pi) compared to those having a normal Pi. METHODS:  The Pi data were abstracted from electronic files collected on 7183 paired SpO2-SaO2 samples (3201 Black and 3982 White) from a recently reported desaturation study of 75 subjects (39 Black and 36 White) where SaO2 values were sequentially decreased from 100 to 70%. The Pi values from that dataset were divided into two groups (Pi ≤ 1 or Pi > 1) for analysis. A Pi value ≤ 1 was considered "low perfusion" and a Pi value > 1 was considered "normal perfusion". Statistical calculations included values of bias (mean difference of SpO2-SaO2), precision (standard deviation of the difference), and accuracy (root-mean-square error [ARMS]). During conditions of low perfusion (Pi ≤ 1, range [0.1 to 1]), overall bias and precision were + 0.48% ± 1.59%, while bias and precision were + 0.19 ± 1.53%, and + 0.91 ± 1.57%, for Black and White subjects, respectively. RESULTS:  During normal perfusion (Pi > 1, range [1 to 12]), overall bias and precision were + 0.18% ± 1.34%, while bias and precision were -0.26 ± 1.37%, and - 0.12 ± 1.31%, for Black and White subjects, respectively. ARMS was 1.37% in all subjects with normal perfusion and 1.64% in all subjects with low perfusion. CONCLUSION:  Masimo SET® pulse oximeters with RD SET® sensors are accurate for individuals of both Black and White races when Pi is normal, as well as during conditions when Pi is low. The ARMS for all conditions studied is well within FDA standards. This study was conducted in healthy volunteers during well-controlled laboratory desaturations, and results could vary under certain challenging clinical conditions.

Comparison of different forms of Raynaud's phenomenon by LASCA proximal-distal gradient perfusion.

OBJECTIVE: To evaluate finger proximal-distal gradient (PDG) perfusion in subjects with primary Raynaud's phenomenon (PRP), then making comparisons with systemic sclerosis (SSc) patients and healthy controls (HC). METHODS: Consecutive adult PRP subjects were enrolled, along with an equal number of SSc and HC. Peripheral blood perfusion of the hands was assessed by laser speckle contrast analysis (LASCA). PDG was then calculated applying a generalizable formula independent of both intra- and inter-personal factors. Non-specific anti-nuclear autoantibody (ANA) isolated positivity was assessed. RESULTS: Fifty PRP patients (88 % female, mean age 45 ± 17.9 years) were enrolled, along with 50 SSc patients and 50 HC. After adjusting mean PDG results for age and sex, no significant differences emerged between PRP and SSc (1.80 ± 0.43 vs 1.76 ± 0.53; p = 0.294). Conversely, PRP values were significantly reduced when compared to HC (2.72 ± 0.37; p < 0.001). Among PRP subjects, no significant differences were found regarding isolated ANA positivity (1.86 ± 0.44 vs 1.74 ± 0.44; p = 0.42). CONCLUSION: PRP and SSc seems to share the same basal PDG perfusion impairment assessed by LASCA. Isolated ANA positivity, in the absence of clinical and capillaroscopic suspicion for secondary causes, should not be considered an exclusion criterion for PRP classification.

Peripheral perfusion index in well newborns at 6 to 72 h of life at different altitudes: a multi-center study in China.

The purpose of this study is to obtain the reference range of peripheral perfusion index (PPI) of asymptomatic well newborns at 6 to 72 h of life at different altitudes. A population-based prospective cohort study was conducted in cities at different altitudes in China. Asymptomatic well newborns were enrolled consecutively from six hospitals with an altitude of 4 to 4200 m between February 1, 2020, and April 15, 2021. PPI was measured at 6, 12, 24, 48, and 72 h after birth on the right hand (pre-ductal) and either foot (post-ductal) using a Masimo SET Radical-7 oximeter. Fiftieth percentile reference curves of the pre- and post-ductal PPI values at 6-72 h after birth were generated using the Lambda Mu Sigma method. Linear mixed-effects regression was performed to determine the influence of different altitude levels on PPI values over different measurement time points. A total of 4257 asymptomatic well newborns were recruited for analysis. The median and quartile pre- and post-ductal PPI values at 6-72 h of life at different altitudes were 1.70 (1.20, 2.60) and 1.70 (1.10, 2.70) for all infants, 1.30 (1.10, 1.90) and 1.10 (0.88, 1.80) for infants at low altitude, 1.40 (1.00, 2.00) and 1.30 (0.99, 2.00) at mild altitudes, 1.90 (1.30, 2.50) and 1.80 (1.20, 2.70) at moderate altitudes, 1.80 (1.40, 3.50) and 2.20 (1.60, 4.30) for high altitudes, 3.20 (2.70, 3.70), and 3.10 (2.10, 3.30) for higher altitudes, respectively. Overall, both pre- and post-ductal PPI increased with altitude. The 50th percentile curves of pre- and post-ductal PPI values in well newborns at mild, low, moderate, and high altitudes were relatively similar, while the difference between the PPI curves of infants at higher altitudes and other altitudes was significantly different.  Conclusions: With the increase of altitude, pre- and post-ductal PPI of newborns increases. Our study obtained the PPI reference values of asymptomatic well newborns at 6 to 72 h after birth at different altitudes from 4 to ≥ 4000 m. What is Known: • Monitoring hemodynamics is very important to neonates. As an accurate and reliable hemodynamic monitoring index, PPI can detect irreversible damage caused by insufficient tissue perfusion and oxygenation early, directly, noninvasively, and continuously. What is New: • Our study obtained the PPI reference values of asymptomatic well newborns at 6 to 72 h after birth at different altitudes from 4 to ≥ 4000 m. With the increase of altitude, pre- and post-ductal PPI of newborns increase with statistical significance. Therefore, the values and disease thresholds of PPI for asymptomatic neonates should be modified according to altitudes.

Perfusion index in newborns with CHD without clinical signs of hypoperfusion and heart failure: comparison with healthy newborns.

INTRODUCTION: Peripheral perfusion index has been proposed as a possible method for detecting circulatory impairment. We aimed to determine the normal range of peripheral perfusion index in healthy newborns and compare it with that of newborns with CHD. METHODS: Right-hand saturation and right-hand peripheral perfusion index levels were recorded, and physical examination and echocardiography were performed in newborns who were 0-28 days old and whom were evaluated in our paediatric cardiology outpatient clinic. The saturation and peripheral perfusion index levels of newborns with normal heart anatomy and function were compared with those of newborns with CHD. RESULTS: Out of 358 newborns (238 mature and 75 premature) enrolled in the study, 39 had CHD (20 mild CHD, 13 moderate CHD, and 6 severe CHD), of which 29 had CHD with left-to-right shunting, 5 had obstructive CHD, and 5 had cyanotic CHD. No newborn had clinical signs of hypoperfusion or heart failure, such as prolonged capillary refill, weakened pulses, or coldness of extremities. Peripheral perfusion index level was median (interquartile range) 1.7 (0.6) in healthy newborns, 1.8 (0.7) in newborns with mild CHD, and 1.8 (0.4) in newborns with moderate and severe CHD, and there was no significant difference between the groups regarding peripheral perfusion index level. CONCLUSION: Peripheral perfusion index remains unchanged in newborns with CHD without the clinical signs of hypoperfusion or heart failure. Larger studies with repeated peripheral perfusion index measurements can determine how valuable this method will be in the follow-up of newborns with CHD.

"The peripheral perfusion index discriminates haemodynamic responses to induction of general anaesthesia".

Induction of general anaesthesia is often accompanied by hypotension. Standard haemodynamic monitoring during anaesthesia relies on intermittent blood pressure and heart rate. Continuous monitoring systemic blood pressure requires invasive or advanced modalities creating a barrier for obtaining important information of the circulation. The Peripheral Perfusion Index (PPI) is obtained non-invasively and continuously by standard photoplethysmography. We hypothesized that different patterns of changes in systemic haemodynamics during induction of general anaesthesia would be reflected in the PPI. Continuous values of PPI, stroke volume (SV), cardiac output (CO), and mean arterial pressure (MAP) were evaluated in 107 patients by either minimally invasive or non-invasive means in a mixed population of surgical patients. 2 min after induction of general anaesthesia relative changes of SV, CO, and MAP was compared to the relative changes of PPI. After induction total cohort mean(± st.dev.) MAP, SV, and CO decreased to 65(± 16)%, 74(± 18)%, and 63(± 16)% of baseline values. In the 38 patients where PPI decreased MAP was 57(± 14)%, SV was 63(± 18)%, and CO was 55(± 18)% of baseline values 2 min after induction. In the 69 patients where PPI increased the corresponding values were MAP 70(± 15)%, SV 80(± 16)%, and CO 68(± 17)% (all differences: p < 0,001). During induction of general anaesthesia changes in PPI discriminated between the degrees of reduction in blood pressure and algorithm derived cardiac stroke volume and -output. As such, the PPI has potential to be a simple and non-invasive indicator of the degree of post-induction haemodynamic changes.

Definition and application of proximal-distal gradient finger perfusion in systemic sclerosis by laser speckle contrast analysis.

OBJECTIVE: In patients with systemic sclerosis (SSc) the perfusion of the fingers shows an alteration of the physiological proximal-distal gradient (PDG). The aim of this study is to provide a generalizable definition of PDG, applying it in a cohort of SSc patients and healthy controls (HC) using laser speckle contrast analysis (LASCA). METHODS: Adult consecutive SSc patients and HC were enrolled. Peripheral blood perfusion of the hands was evaluated by LASCA, subsequently obtaining 3 different regions of interest: from the distal interphalangeal joint to the fingertip (DIST), from the metacarpophalangeal joint to the distal interphalangeal joint (PROX), and of the whole finger (TOT). A PDG formula independent of both intra- and inter-personal factors was then built. The PDG formula so obtained was: [(DIST × 2.63) - PROX]/TOT. RESULTS: Ninety-four SSc patients (79.8% female, mean age 58.7 years) were enrolled. Applying the PDG formula, SSc patients revealed mean PDG values significantly lower than HC (1.82 ± 0.44 PU vs 2.70 ± 0.38 PU; p < 0.0001). Patients with a previous history of digital ulcers presented significant lower PDG values (p = 0.002). The ROC curve analysis identified in 2.28 PU the best PDG cut-off value between SSc and HC, with 86% sensibility and 90% specificity. CONCLUSION: This study provided a PDG formula generalizable to all kind of subjects, applying it in SSc with great sensibility and specificity using LASCA, the best non-invasive imaging technique for the dynamical evaluation of peripheral perfusion. LASCA-PDG appears also as a tool able to identify a subclinical microangiopathic impairment.

Transcutaneous blood gas monitoring and tissue perfusion during common femoral thromboendarterectomy.

BACKGROUND: Improving tissue perfusion can improve clinical outcomes in surgical patients, where monitoring may aid clinicians in detecting adverse conditions and guide interventions. Transcutaneous monitoring (TCM) of oxygen (tcpO2) and carbon dioxide (tcpCO2) is a well-proven technology and could potentially serve as a measure of local circulation, perfusion and metabolism, but the clinical use is not thoroughly explored. The purpose of this proof-of-concept study was to investigate whether TCM of blood gasses could detect changes in perfusion during major vascular surgery. METHODS: Ten patients with peripheral arterial disease scheduled for lower limb major arterial revascularization under general anaesthesia were consecutively included. TcpO2 and tcpCO2 were continuously recorded from anaesthesia induction until skin closure with a TCM monitor placed on both legs and the thorax. Peripheral oxygen saturation was kept ≥94% and mean arterial blood pressure ≥65 mmHg. The primary outcomes were changes in tcpO2 and tcpCO2 related to arterial clamping and declamping during the procedure and analyzed by paired statistics. RESULTS: Femoral artery clamping resulted in a significant decrease in tcpO2 (-2.1 kPa, IQR-4.2; -0.8), p=.017)), followed by a significant increase in response to arterial declamping (5.5 kPa, IQR 0-7.3), p=.017)). Arterial clamping resulted in a statistically significant increase in tcpCO2 (0.9 kPa, IQR 0.3-5.4), p=.008)) and a significant decrease following declamping (-0.7 kPa, IQR -2.6; -0.2), p=.011)). CONCLUSION: Transcutaneous monitoring of oxygen and carbon dioxide is a feasible method for detection of extreme changes in tissue perfusion during arterial clamping and declamping, and its use for improving patient outcomes should be explored. Clinical Trials identifier: NCT04040478. Registered on July 31, 2019.

Low peripheral perfusion index values may indicate the need for antivenom in the early phase of scorpion envenomation.

BACKGROUND: Scorpion envenomation may cause local symptoms as well as life-threatening situations including shock, and death. Antivenom administration is the cornerstone of therapy, meticulous patient selection is needed because of the possible side effects of the antivenom including anaphylaxis. Peripheral perfusion index (PPI) is a simple, non-invasive test that is widely used for the detection of peripheral hypoperfusion. We aimed to investigate the value of using PPI to predict the need for antivenom administration for scorpion envenomation. METHODS: This prospective observational study was conducted in the ED of a tertiary care center. We consecutively enrolled patients with scorpion envenomation on the extremities who are over 18 years old without pregnancy and a peripheral arterial disease between March 1, 2021, to October 31, 2021. Demographics included age, sex, sting zone, the time between sting and the ED admission, and vital parameters, we blindly measured PPI both on affected and contralateral extremities before any therapeutic intervention. We compared PPI levels, vital parameters, and the outcome including discharge from the ED, admission to ward or ICU, and death between patients who received antivenom and those who did not. RESULTS: Twenty-nine male (58.0%) and 21 (42.0%) female patients with scorpion envenomation were enrolled in the study. The median age was 46.5 [IQR 33.3]. Thirty-eight (76.0%) patients had Class I, 12 (24.0%) patients had Class II and III envenomation. The median duration of the ED admission after the sting was 90 [IQR 120] minutes. Antivenom was administered in 13 (26.0%) patients. PPI was significantly lower both on the affected and the contralateral extremities (p = 0.043 and p = 0.045, respectively) in patients who required antivenom. With a cut-off value of 2.4, PPI can predict the need for antivenom with a sensitivity of 61.54%, a specificity of 86.5%, a positive likelihood ratio of 4.55, a negative likelihood ratio of 0.44, a positive predictive value of 61.54%, a negative predictive value of 86.49%, and an accuracy of 80% (AUC 0.691, p < 0.05). CONCLUSION: PPI can better reflect the ongoing systemic inflammation and the need for antivenom compared to other vital parameters. Therefore, we suggest this noninvasive and objective test may have a significant role in detecting patients who need antivenom in the early phase of scorpion envenomation. However, more studies are needed to elucidate the role of PPI in scorpion envenomation.

Value of peripheral perfusion index to predict acute limb ischaemia in newborns after peripheral artery cannulation.

AIMS AND OBJECTIVES: To investigate the feasibility of using peripheral perfusion index (PPI) to monitor acute limb ischaemia (ALI) in newborns after catheterisations. BACKGROUND: ALI is common complication of neonatal peripheral artery cannulation. It is important to address as soon as the early signs of ALI. PPI could aid in noninvasive evaluation of distal extremity perfusion in an effort to notify risk of potential ischaemic injury from catheterisations. DESIGN: A nested case-control study. METHODS: Clinical information of newborns who had been admitted to the Neonatal Intensive Care Unit of Jiangxi Provincial Children's Hospital and had received peripheral artery cannulation from January 2018 to January 2020 was prospectively collected. Transcutaneous blood oxygen saturation (TcSO2 ), PPI and delta-PPI (ΔPPI1; the difference in PPI values of the two arms. ΔPPI2; difference in the PPI values before and after cannulation) were recorded. We used STROBE checklist as an EQUATOR in this study. RESULTS: A total of 25 newborns with ALI were included in the study. These were then paired with 100 newborns without ALI. The PPI and TcSO2 of the cannulated limb were significantly lower in the ALI group than in the non-ALI (NALI) group (p < .05). The area under the receiver-operating characteristic curve was significant for ΔPPI1. The ΔPPI1 had a sensitivity and specificity of 92% and 87%, respectively, for diagnosing ALI. ΔPPI1 greater than 0.315 suggested that the infant was at risk of ALI. CONCLUSIONS: Monitoring the change in the PPI in newborns after catheterisations helped in the early assessment of ALI. RELEVANCE TO CLINICAL PRACTICE: Drops in the PPI and TcSO2 of the cannulated limbs might, to some extent, reflect the possibility of ALI in newborns. ΔPPI1 (the difference in PPI values of the two arms) proved to be a simple, objective parameter to predict the presence of ALI.

Capillary refill time for the management of acute circulatory failure: a survey among pediatric and adult intensivists.

INTRODUCTION: Recent studies have shown the prognostic value of capillary refill time (CRT) and suggested that resuscitation management guided by CRT may reduce morbidity and mortality in patients with septic shock. However, little is known about the current use of CRT in routine clinical practice. This study aimed to assess the modalities of CRT use among French adult and pediatric intensivists. METHODS: A cross-sectional survey exploring CRT practices in acute circulatory failure was performed. The targeted population was French adult and pediatric intensivists (SFAR and GFRUP networks). An individual invitation letter including a survey of 32 questions was emailed twice. Descriptive and analytical statistics were performed. RESULTS: Among the 6071 physicians who received the letter, 418 (7%) completed the survey. Among all respondents, 82% reported using CRT in routine clinical practice, mainly to diagnose acute circulatory failure, but 45% did not think CRT had any prognostic value. Perfusion goal-directed therapy based on CRT was viewed as likely to improve patient outcome by 37% of respondents. The measurement of CRT was not standardized as the use of a chronometer was rare (3%) and the average of multiple measurements rarely performed (46%). Compared to adult intensivists, pediatric intensivists used CRT more frequently (99% versus 76%) and were more confident in its diagnostic value and its ability to guide treatment. CONCLUSION: CRT measurement is widely used by intensivists in patients with acute circulatory failure but most often in a non-standardized way. This may lead to a misunderstanding of CRT reliability and clinical usefulness.

Association of the intraoperative peripheral perfusion index with postoperative morbidity and mortality in acute surgical patients: a retrospective observational multicentre cohort study.

BACKGROUND: We hypothesised that in acute high-risk surgical patients, a lower intraoperative peripheral perfusion index (PPI) would indicate a higher risk of postoperative complications and mortality. METHODS: This retrospective observational study included 1338 acute high-risk surgical patients from November 2017 until October 2018 at two University Hospitals in Denmark. Intraoperative PPI was the primary exposure variable and the primary outcome was severe postoperative complications defined as a Clavien-Dindo Class ≥III or death, within 30 days. RESULTS: intraoperative PPI was associated with severe postoperative complications or death: odds ratio (OR) 1.12 (95% confidence interval [CI] 1.05-1.19; P<0.001), with an association of intraoperative mean PPI ≤0.5 and PPI ≤1.5 with the primary outcome: OR 1.79 (95% CI 1.09-2.91; P=0.02) and OR 1.65 (95% CI 1.20-2.27; P=0.002), respectively. Each 15-min increase in intraoperative time spend with low PPI was associated with the primary outcome (per 15 min with PPI ≤0.5: OR 1.11 (95% CI 1.05-1.17; P<0.001) and with PPI ≤1.5: OR 1.06 (95% CI 1.02-1.09; P=0.002)). Thirty-day mortality in patients with PPI ≤0.5 was 19% vs 10% for PPI >0.5, P=0.003. If PPI was ≤1.5, 30-day mortality was 16% vs 8% in patients with a PPI >1.5 (P<0.001). In contrast, intraoperative mean MAP ≤65 mm Hg was not significantly associated with severe postoperative complications or death (OR 1.21 [95% CI 0.92-1.58; P=0.2]). CONCLUSIONS: Low intraoperative PPI was associated with severe postoperative complications or death in acute high-risk surgical patients. To guide intraoperative haemodynamic management, the PPI should be further investigated.

Associations between peripheral perfusion disorders, mean arterial pressure and dose of norepinephrine administrated in the early phase of septic shock.

The aim of the study was to explore the correlations between peripheral perfusion, mean arterial pressure and the dose-rate of norepinephrine (NE) infused for the treatment of septic shock. The study is retrospective analysis of data acquired prospectively on 57 patients during the first 24 hours after the occurrence of the shock. Clinical and haemodynamic characteristics, skin perfusion parameters (capillary refill time [CRT], mottling score and temperature gradients) and the dose rate of NE infusion were collected. Negative correlations between mean arterial pressure (MAP) and temperature gradients (core-to-toe: P = .03, core-to-index: P = .04) were found and abnormal CRT was associated with lower MAP (P = .02). The dose rate of NE was negatively correlated with temperature gradients (core-to-toe: P = .02, core-to-index: P = .01, forearm-to-index: P = .008) in the overall population. In patients receiving NE for at least 12 hours, the NE dose rate positively was correlated with the mottling score (P = .006), temperature gradients (core-to-toe: P = .04, forearm-to-index: P = .02, core-to-index: P = .005) and CRT (P = .001). The dose of NE administrated was associated with 14-days mortality (odds ration [OR] = 1.21 [1.06-1.38], P = .006) and with 28-days mortality (OR = 1.17 [1.01-1.36], P = 0.04). In conclusion, the study described the presence of correlations between peripheral perfusion and MAP and between peripheral perfusion and the dose rate of NE infusion.

Peripheral perfusion index as a predictor of failed weaning from mechanical ventilation.

We hypothesized that impairment of peripheral perfusion index (PPI) during spontaneous breathing trial (SBT) might be predictive of weaning failure. We included 44 consecutive, adult, patients, who were scheduled for weaning after at least 48 h of invasive mechanical ventilation in this prospective observational study. Weaning failure was defined as failed SBT or reintubation within 48 h of extubation. PPI readings were obtained before initiation of the SBT, and every 5 min till the end of the SBT. PPI ratio was calculated at every time point as: PPI value/ baseline PPI. The primary outcome was the accuracy of PPI ratio at the end of the SBT in detecting failed weaning. Forty-three patients were available for the final analysis. Eighteen patients (42%) were considered failed weaning. PPI ratio was higher in patients with successful weaning compared to patients with failed weaning during the last 15 min of the SBT. PPI ratio at the end of SBT was higher in patients with successful weaning compared to patients with failed weaning. PPI ratio at the end of SBT had good predictive ability for weaning failure {area under receiver operating characteristic curve (95% confidence interval): 0.833(0.688-0.929), cutoff value ≤ 1.41}. The change in PPI during SBT is an independent predictor for re-intubation. PPI could be a useful tool for monitoring the patient response to SBT. Patients with successful weaning showed higher augmentation of PPI during the SBT compared to re-intubated patients. Failure of augmenting the PPI by 41% at the end of SBT could predict re-intubation with negative predictive value of 95%. Clinical trial identifier: NCT03974568. https://clinicaltrials.gov/ct2/show/NCT03974568?term=ahmed+hasanin&draw=3&rank=17.

Evaluation of accuracy of capillary refill index with pneumatic fingertip compression.

Capillary refill time (CRT) is a method of measuring a patient's peripheral perfusion status through a visual assessment performed by a clinician. We developed a new method of measuring CRT using standard pulse oximetry sensor, which was designated capillary refill index (CRI). We evaluated the accuracy of CRI in comparison to CRT image analysis. Thirty healthy adult volunteers were recruited for a derivation study and 30 patients in the emergency department (ED) were for validation. Our high fidelity mechanical device compresses and releases the fingertip to measure changes in blood volume using infrared-light (940 nm). CRT was calculated by image analysis software using recorded fingertip videos. CRI and CRT were measured at: room temperature (ROOM TEMP), 15 °C cold water (COLD), and 38 °C warm water (REWARM). Intra-rater reliability, Bland-Altman plots, and correlation coefficients were used to evaluate the accuracy of the novel CRI method. CRI (4.9 [95% CI 4.5-5.3] s) and CRT (4.0 [3.6-4.3]) in the COLD group were higher than the ROOM TEMP and REWARM groups. High intra-rater reliability was observed in both measurements (0.97 [0.95-0.98] and 0.98 [0.97-0.99], respectively). The Bland-Altman plots suggested a systematic bias: CRI was consistently higher than CRT (difference: + 1.01 s). There was a strong correlation between CRI and CRT (r = 0.89, p < 0.001). ED patients had higher CRI (3.91 [5.05-2.75]) and CRT (2.21 [3.19-1.23]) than those of healthy volunteers at room temperature. The same difference and correlation patterns were verified in the ED setting. CRI was as reliable as CRT by image analysis. The values of CRI was approximately 1 s higher than CRT.