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.

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.

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.

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.

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.

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.

The ability of pulse oximetry-derived peripheral perfusion index to detect fluid responsiveness in patients with septic shock.

BACKGROUND: Fluid challenge test is a widely used method for the detection of fluid responsiveness in acute circulatory failure. However, detection of the patient's response to the fluid challenge requires monitoring of cardiac output which is not feasible in many settings. We investigated whether the changes in the pulse oximetry-derived peripheral perfusion index (PPI), as a non-invasive surrogate of cardiac output, can detect fluid responsiveness using the fluid challenge test or not. METHODS: We prospectively enrolled 58 patients with septic shock on norepinephrine infusion. Fluid challenge test, using 200 mL crystalloid solution, was performed in all study subjects. All patients received an additional 300 mL crystalloid infusion to confirm fluid responsiveness. Velocity time integral (VTI) (using transthoracic echocardiography), and PPI were measured at the baseline, after 200 mL fluid challenge, and after completion of 500 mL crystalloids. Fluid responsiveness was defined by 10% increase in the VTI after completion of the 500 mL. The predictive ability of ∆PPI [Calculated as (PPI after 200 mL - baseline PPI)/baseline PPI] to detect fluid responders was obtained using the receiver operating characteristic curve. RESULTS: Forty-two patients (74%) were fluid responders; in whom, the mean arterial pressure, the central venous pressure, the VTI, and the PPI increased after fluid administration compared to the baseline values. ∆PPI showed moderate ability to detect fluid responders [area under receiver operating characteristic curve (95% confidence interval) 0.82 (0.70-0.91), sensitivity 76%, specificity 80%, positive predictive value 92%, negative predictive value 54%, cutoff value ≥ 5%]. There was a significant correlation between ∆PPI and ∆VTI induced by the fluid challenge. CONCLUSION: ∆PPI showed moderate ability to detect fluid responsiveness in patients with septic shock on norepinephrine infusion. Increased PPI after 200 mL crystalloid challenge can detect fluid responsiveness with a positive predictive value of 92%; however, failure of the PPI to increase does not exclude fluid responsiveness. CLINICAL TRIAL IDENTIFIER: NCT03805321. Date of registration: 15 January 2019. Clinical trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03805321?term=ahmed+hasanin&rank=9 .

Prognostic performance of peripheral perfusion index and shock index combined with ESI to predict hospital outcome.

INTRODUCTION: Peripheral perfusion index (PPI) and shock index (SI) are considered valuable predictors of hospital outcome and mortality in various operative and intensive care settings. In the present study, we evaluated the prognostic capabilities of these parameters for performing emergency department (ED) triage, as represented by the emergency severity index (ESI). METHODS: This prospective cross-sectional study included 367 patients aged older than 18 years who visited the ED of a tertiary referral hospital. The ESI triage levels with PPI, SI, and other basic vital sign parameters were recorded for each patient. The hospital outcome of the patients at the end of the ED period, such as discharge, admission to the hospital and death were recorded. RESULTS: A total of 367 patients (M/F: 178/189) admitted to the ED were categorized according to ESI and included in the study. A decrease in diastolic BP, SpO2 and PPI increased the likelihood of hospitalization and 30-day mortality. Based on univariate analysis, a significant improvement in performance was found by using age, diastolic BP, mean arterial pressure, SpO2, SI and PPI in terms of predicting high acuity level patients (ESI < 3). In the multivariable analysis only SpO2 and PPI were found to predict ESI < 3 patients. CONCLUSION: Peripheral perfusion index and SI as novel triage instruments might provide useful information for predicting hospital admission and mortality in ED patients. The addition of these parameters to existing triage instruments such as ESI could enhance the triage specificity in unselected patients admitted to ED.

Peripheral perfusion index predicting prolonged ICU stay earlier and better than lactate in surgical patients: an observational study.

BACKGROUND: Peripheral perfusion index (PPI) is an indicator reflecting perfusion. Patients undergoing long time surgeries are more prone to hypoperfusion and increased lactate. Few studies focusing on investigating the association between PPI and surgical patients' prognoses. We performed this study to find it out. METHODS: From January 2019 to September 2019, we retrospected all surgical patients who were transferred to ICU, Xinyang Central hospital, Henan province, China. Inclusive criteria: age ≥ 18 years old; surgical length ≥ 120 min. Exclusive criteria: died in ICU; discharging against medical advice; existing diseases affecting blood flow of upper limbs, for example, vascular thrombus in arms; severe liver dysfunction. We defined "prolonged ICU stay" as patients with their length of ICU stay longer than 48 h. According to the definition, patients were divided into two groups: "prolonged group" (PG) and "non-prolong group" (nPG). Baseline characteristics, surgical and therapeutic information, ICU LOS, SOFA and APACHE II were collected. Besides we gathered data of following parameters at 3 time points (T0: ICU admission; T1: 6 h after admission; T2: 12 h after admission): mean artery pressure (MAP), lactate, heart rate (HR), PPI and body temperature. Data were compared between the 2 groups. Multivariable binary logistic regression and ROC (receiver operating characteristic) curves were performed to find the association between perfusion indictors and ICU LOS. RESULTS: Eventually, 168 patients were included, 65 in PG and 103 in nPG. Compared to nPG, patients in PG had higher blood lactate and lower PPI. PPI showed significant difference between two groups earlier than lactate (T0 vs T1). The value of PPI at two time points was lower in PG than nPG(T0: 1.09 ± 0.33 vs 1.41 ± 0.45, p = 0.001; T1: 1.08 ± 0.37 vs 1.49 ± 0.41, p < 0.001). Increased lactateT1(OR 3.216; 95% CI 1.253-8.254, P = 0.015) and decreased PPIT1 (OR 0.070; 95% CI 0.016-0.307, P < 0.001) were independently associated with prolonged ICU stay. The area under ROC of the PPIT1 for predicting ICU stay> 48 h was 0.772, and the cutoff value for PPIT1 was 1.35, with 83.3% sensitivity and 73.8% specificity. CONCLUSIONS: PPI and blood lactate at T1(6 h after ICU admission) are associated with ICU LOS in surgical patient. Compared to lactate, PPI indicates hypoperfusion earlier and more accurate in predicting prolonged ICU stay.

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. The Peripheral Perfusion Index (PPI) is obtained continuously and non-invasively by standard photoplethysmography. We hypothesized that changes in indices of systemic blood flow during general anaesthesia would be reflected in the PPI. PPI, stroke volume (SV), cardiac output (CO) and mean arterial pressure (MAP) were evaluated in 20 patients. During general anaesthesia but before start of surgery relative changes of SV, CO and MAP were compared to the relative changes of PPI induced by head-up (HUT) and head-down tilt (HDT). Furthermore, the effect of phenylephrine (PE) during HUT on these parameters was investigated. ∆PPI correlated significantly (p < 0.001) with ∆SV (r = 0.9), ∆CO (r = 0.9), and ∆MAP (r = 0.9). HUT following induction of anaesthesia resulted in a decrease in PPI of 41% (25-52) [median (IQR)], SV 27% (23-31), CO 27% (25-35), and MAP 28% (22-35). HDT led to an increase in PPI of 203% (120-375), SV of 29% (21-41), CO 22% (16-34), and MAP 47% (42-60). 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.

Evaluation of peripheral perfusion index and heart rate variability as early predictors for intradialytic hypotension in critically ill patients.

BACKGROUND: Intradialytic hypotension is a serious complication during renal replacement therapy in critically ill patients. Early prediction of intradialytic hypotension could allow adequate prophylactic measures. In this study we evaluated the ability of peripheral perfusion index (PPI) and heart rate variability (HRV) to predict intradialytic hypotension. METHODS: A prospective observational study included 36 critically ill patients with acute kidney injury during their first session of intermittent hemodialysis. In addition to basic vital signs, PPI was measured using Radical-7 (Masimo) device. Electrical cardiometry (ICON) device was used for measuring cardiac output, systemic vascular resistance, and HRV. All hemodynamic values were recorded at the following time points: 30 min before the hemodialysis session, 15 min before the start of hemodialysis session, every 5 min during the session, and 15 min after the conclusion of the session. The ability of all variables to predict intradialytic hypotension was assessed through area under receiver operating characteristic (AUROC) curve calculation. RESULTS: Twenty-three patients (64%) had intradialytic hypotension. Patients with pulmonary oedema showed higher risk for development of intradialytic hypotension {Odds ratio (95% CI): 13.75(1.4-136)}. Each of baseline HRV, and baseline PPI showed good predictive properties for intradialytic hypotension {AUROC (95% CI): 0.761(0.59-0.88)}, and 0.721(0.547-0.857)} respectively. CONCLUSIONS: Each of low PPI, low HRV, and the presence of pulmonary oedema are good predictors of intradialytic hypotension.

Pre-operative haemodynamic monitoring and resuscitation in hip fracture patients: Protocol for a prospective observational study.

BACKGROUND: In a frail patient group often suffering from dehydration, hip fracture is potentially fatal partly because of the blood loss and thus deteriorated circulation. An important goal for haemodynamic monitoring and resuscitation is early detection of insufficient tissue perfusion. "The peripheral perfusion index" reflects changes in peripheral perfusion and blood volume. We hypothesize that hip fracture patients are hypovolaemic with poor peripheral perfusion and accordingly respond to controlled fluid resuscitation. The peripheral perfusion index might reflect restricted tissue perfusion in spite of stable central haemodynamic variables. METHODS: This prospective observational study assess to what extend hip fracture patients suffer from hypovolaemia and respond to a stroke volume-guided fluid challenge. The secondary objectives are to evaluate correlation between the non-invasive peripheral perfusion index and minimally invasive measures of stroke volume, changes in blood volume and near-infrared spectroscopy determined tissue- and cerebral oxygenation and to compare results to prevalence of post-operative complications including mortality. We will include 50 patients (>65 years) presenting a hip fracture and treated in a multimodal fast-track regimen when written informed consent is available. DISCUSSION: This is likely the first study to address pre-operative haemodynamic monitoring and resuscitation in hip fracture patients where adequate resuscitation is easily missed. We aim to evaluate feasibility of pre-operative stroke volume-guided haemodynamic optimization in the context of minimally- and non-invasive monitoring of peripheral perfusion and measure of blood volume.

Early peripheral perfusion index predicts 28-day outcome in patients with septic shock.

BACKGROUND: To investigate the prognostic value of the peripheral perfusion index (PPI) in patients with septic shock. METHODS: This prospective cohort study, conducted at the emergency intensive care unit of Peking University People's Hospital, recruited 200 patients with septic shock between January 2023 and August 2023. These patients were divided into survival (n=84) and death (n=116) groups based on 28-day outcomes. Clinical evaluations included laboratory tests and clinical scores, with lactate and PPI values assessed upon admission to the emergency room and at 6 h and 12 h after admission. Risk factors associated with mortality were analyzed using univariate and multivariate Cox regression analyses. Receiver operator characteristic (ROC) curve was used to assess predictive performance. Mortality rates were compared, and Kaplan-Meier survival plots were created. RESULTS: Compared to the survival group, patients in the death group were older and had more severe liver damage and coagulation dysfunction, necessitating higher norepinephrine doses and increased fluid replacement. Higher lactate levels and lower PPI levels at 0 h, 6 h, and 12 h were observed in the death group. Multivariate Cox regression identified prolonged prothrombin time (PT), decreased 6-h PPI and 12-h PPI as independent risk factors for death. The area under the curves for 6-h PPI and 12-h PPI were 0.802 (95% CI 0.742-0.863, P<0.001) and 0.945 (95% CI 0.915-0.974, P<0.001), respectively, which were superior to Glasgow Coma Scale (GCS), Sequential Organ Failure Assessment (SOFA) scores (0.864 and 0.928). Cumulative mortality in the low PPI groups at 6 h and 12 h was significantly higher than in the high PPI groups (6-h PPI: 77.52% vs. 22.54%; 12-h PPI: 92.04% vs. 13.79%, P<0.001). CONCLUSION: PPI may have value in predicting 28-day mortality in patients with septic shock.