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.

Can peripheral perfusion index predict disease mortality in COVID-19 patients in the emergency department.

Background: Coronavirus disease 2019 (COVID-19) pneumonia remains a major public health concern. The prognostic efficacy of Peripheral Perfusion Index (PPI) has been researched in different pathologies such as trauma and sepsis. We hypothesized that PPI may serve as predictor of mortality in hospitalized patients with COVID-19 infection. This study aimed to describe the association between PPI at admission and COVID-19 mortality, a new mortality prediction tool. Methods: This retrospective, observational study was conducted at a tertiary care center in Turkey. Adult patients diagnosed with COVID-19 infection were enrolled in this study between Februrary 15, 2022 to April 15, 2023. Patient demographic and clinical data including vital signs, laboratory parameters and PPI on admission were collected from an electronic database. PPI was measured using Philips G30E patient monitor system. The primary outcome was in-hospital mortality. Results: In total, 200 patients with COVID-19 infection were included and 42 (21 %) in-hospital deaths were identified. For all parameters of study, age, oxygen saturation, respiratory rate, PPI, urea, creatinine, White Blood Cell (WBC), and High-sensitive cardiac Troponin T (hs-cTnT) values were significantly different between survivors vs non-survivors. hs-cTnT >21,25 pg/mL[HR:2.823 (95 % CI:1.211-6583)], PPI <2,15 [HR:2485 (95 % CI:1.194-5.175)], Oxygen saturation <87 % [HR:2258 (95 % CI:1.191-4.282)], and WBC >9680 x103/ml [HR:2.124 (95 % CI:1.083-4.163)] were independent predictors of in-hospital mortality. Conclusions: This study identified the factors affecting in-hospital mortality among COVID-19 patients. Importantly, besides many parameter, PPI at admission was significantly associated with COVID-19 mortality and could be a feasible marker in emergency department to identify high risk patients.

The Use of the Perfusion Index to Predict Post-Induction Hypotension in Patients Undergoing General Anesthesia: A Systematic Review and Meta-Analysis.

Post-induction hypotension (PIH) is a common and potentially serious complication of general anesthesia. This meta-analysis (Prospero registration number: CRD42024566321) aimed to evaluate the predictive efficacy of the perfusion index (PI) for PIH in patients undergoing general anesthesia. A comprehensive literature search was performed using multiple electronic databases (Google Scholar, EMBASE, Cochrane Library, and MEDLINE). Studies involving adult patients undergoing general anesthesia, with the PI measured before anesthesia induction and reporting PIH incidence, were included. The primary outcome was the diagnostic accuracy of the PI in predicting the probability of PIH. The secondary outcome was the pooled PIH incidence. Eight studies with 678 patients were included. The pooled incidence of PIH was 44.8% (95% confidence interval [CI]: 29.9%-60.8%). The combined sensitivity and specificity of the PI for predicting PIH were 0.84 (95% CI: 0.65-0.94) and 0.82 (95% CI: 0.70-0.90), respectively. The summary receiver operating characteristic (sROC) analysis revealed an area under curve of 0.89 (95% CI: 0.86-0.92). The Deek's funnel plot asymmetry test indicated no significant publication bias. The PI demonstrates high predictive efficacy for PIH in patients undergoing general anesthesia, indicating that it can be a valuable tool for identifying those at risk of PIH.

Characterization of myocardial perfusion imaging systems - an extension of quality metrics.

PURPOSE: The aim of this study was to evaluate the performance of myocardial perfusion imaging (MPI) systems in detecting perfusion defects (PDs). The defect perfusion index (DPI) was introduced to extend and further advance the current MPI quality metrics. METHODS: An anthropomorphic phantom simulating normal and pathological myocardial perfusion conditions was imaged by various NaI-crystal detector systems with and without corrections for scatter (SC) and attenuation (AC) (Symbia, Symbia + SC, Symbia IQ + SCAC, Symbia IQ), and cadmium-zinc-telluride detector systems without corrections (DSPECT, D530c). The extent of PD and the summed score (SS) were obtained by comparing polar maps with ad hoc normal databases created for each MPI system by using phantom polar maps with normal perfusion. The segmental uptake (SU) and the global uniformity (GU) were evaluated. The DPI was calculated on segments included in the PD to minimize attenuation artifacts outside the PD. The 17 segmental model was used. RESULTS: The highest level of uniformity of polar map was obtained for Symbia IQ + SCAC. D530c showed the highest extent of PD and dependence of the extent on the PD position. It showed in general the lowest SU values and the highest GU due to attenuation artifacts. Nevertheless, D530c outperforms other MPI systems in terms of PD detection, showing the highest DPI value. DSPECT system showed the lowest SS value, and DPI values comparable to NaI-crystal detector systems. CONCLUSION: The DPI can be evaluated to investigate the intrinsic ability of MPI systems to detect PDs, whatever the quantitative post-processing software used.

The Correlation Between Preoperative Perfusion Index and Intraoperative Hypothermia During Laparoscopic Radical Surgery for Urological Malignancies.

This study aimed to explore the relationship between preoperative baseline perfusion index (PI) and intraoperative hypothermia during general anesthesia. PI reflects the peripheral perfusion status, which may be associated with the decrease of core temperature during general anesthesia, as the redistribution of temperature from the core compartment to the peripheral compartment depends on the peripheral perfusion status. A total of 68 patients underwent radical surgery for urological malignancies in this study. The baseline PI value was measured upon entering the operating room. Core temperature was continuously monitored using a nasal pharyngeal probe from anesthesia induction to the end of surgery, with temperature data recorded every 15 minutes. Univariate and multivariate logistic regression analyses were used to identify risk factors for intraoperative hypothermia. Intraoperative hypothermia occurred in 26 patients, whose baseline PI (2.70 ± 0.73) was significantly lower than that of the normothermic group (3.65 ± 1.05), with P<0.05. The baseline PI was independently associated with intraoperative hypothermia (PI: [OR] 0.375, 95% confidence interval [CI]: 1.584-6.876, p = 0.001). This study suggests that low baseline PI is an independent factor associated with intraoperative hypothermia. In future studies, PI value could be considered as a predictor for the treatment of intraoperative hypothermia.

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.

Safety of different cord clamping strategies in the early postnatal period.

BACKGROUND: This study aimed to evaluate the effect of ICC (cord clamping within the first 15 s), DCC (delayed cord clamping at 60 s), and cut-UCM (cut-umbilical cord milking, cord clamping within the first 15 s) groups on oxygen saturation (SpO2), heart rate (HR), and perfusion index (PI) up to 10 min after birth in newborn infants. METHODS: We conducted this randomized clinical trial in the delivery unit of a University Hospital with 189 infants born between 35 and 42 weeks of gestation. Participants were randomly assigned to one of three groups: ICC, DCC, and cut-UCM. The primary outcomes measured were SpO2, HR, and PI at the 1st, 3rd, 5th, and 10th minutes after birth. We utilized ANOVA and Bayesian calculations in this study. RESULTS: There was no difference between the ICC, DCC, and cut-UCM groups in SpO2, HR, and PI values at the 1st, 3rd, 5th, and 10th minutes of life, which did not significantly alter between the three groups in one-way ANOVA. Bayesian repeated-measure ANOVA calculations showed that SpO2 and heart rate results at the 1st, 3rd, 5th, and 10th minutes did not differ between ICC, DCC, and cut-UCM techniques with strong evidence. At the 3rd minute, PI was slightly higher in the DCC and cut-UCM groups compared to the ICC group, with anecdotal evidence. We found no difference between DCC and cut-UCM regarding the 3rd-minute PI, with moderate evidence. CONCLUSION: Umbilical clamping procedures (ICC, DCC, and cut-UCM) did not affect SpO2 and HR in the first ten minutes of life, but 3rd-minute PI values were slightly higher in DCC and cut-UCM compared with ICC among late preterm and term neonates.

Intraoperative changes in upper extremity perfusion index after thoracic paravertebral and intertransverse process block in patients undergoing lung resection surgery.

Background: Perfusion index (PI) has been used as a surrogate marker of sympathetic blockade. This study evaluated changes in PI of bilateral upper extremity after thoracic paravertebral block (PVB) and intertransverse process block (ITPB). Methods: This pilot study included three groups of patients undergoing elective unilateral pulmonary resection under general anesthesia with PVB (n=11) or ITPB (n=10), or urologic procedures with general anesthesia (control group, n=10). Blockades were performed using 10 mL aliquots of 0.5% ropivacaine administered at T3-4, T5-6, and T7-8 intercostal levels immediately after general anesthesia induction. The PI value of the operating side (PI-O) was divided by the contralateral side (PI-CL), and the relative change to baseline was assessed (relative PI-O/PI-CL), with a 50% increase considered meaningful. Results: In all cases within the PVB and ITPB groups, a significant increase in PI was observed following the blockades. The median (1Q, 3Q) intraoperative relative PI-O/PI-CL values were 0.9 (0.8, 1.4), 2.1 (1.4, 2.5), and 1.4 (0.9, 1.9) in the control, PVB, and ITPB groups (P=0.01), respectively. Pairwise comparison revealed a significant difference only between the control and PVB groups (adjusted P=0.01). While the relative PI-O/PI-CL value in the control group generally remained close to 1, occasional fluctuations exceeding 1.5 were noted. Conclusions: PVB induced a noticeable unilateral increase in upper extremity PI, whereas ITPB tended to result in an inconsistent and lesser degree of increase. Monitoring PI values can serve as an indicator of upper extremity sympathetic blockade, but consideration of potential confounders impacting these observations during surgery is essential. Further research is needed to validate these findings.

The Role of the Tissue Perfusion Index in Predicting Disease Severity and Prognosis in Patients with Severe and Critical COVID-19.

OBJECTIVES: The study investigated whether percutaneous partial pressure of oxygen (PtcO2), percutaneous partial pressure of carbon dioxide (PtcCO2), and the derived tissue perfusion index (TPI) can predict the severity and short-term outcomes of severe and critical COVID-19. DESIGN: Prospective observational study conducted from January 1, 2023 to February 10, 2023. SETTING: A teaching hospital specializing in tertiary care in Nanjing City, Jiangsu Province, China. PARTICIPANTS: Adults (≥18 years) with severe and critical COVID-19. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The general information and vital signs of the patients were collected. The PtcO2 and PtcCO2 were monitored in the left dorsal volar. The ratio of TPI was defined as the ratio of PtcO2/fraction of inspired oxygen (FiO2) to PtcCO2. Mortality at 28 was recorded. The ability of the TPI to assess disease severity and predict prognosis was determined. ENDPOINT: Severity of the disease on the enrollment and mortality at 28. RESULTS: A total of 71 patients with severe and critical COVID-19, including 40 severe and 31 critical cases, according to the COVID-19 treatment guidelines published by WHO, were recruited. Their median age was 70 years, with 56 (79%) males. The median SpO2/FiO2, PtcO2, PtcCO2, PtcO2/ FiO2, and TPI values were 237, 61, 42, 143, and 3.6 mm Hg, respectively. Compared with those for severe COVID-19, the TPI, PtcO2/ FiO2, SpO2/FiO2, and PtcO2 were significantly lower in critical COVID-19, while the PtcCO2 was significantly higher. After 28 days, 26 (37%) patients had died. TPI values < 3.5 were correlated with more severe disease status (AUC 0.914; 95% CI: 0.847-0.981, P < 0.001), and TPI < 3.3 was associated with poor outcomes (AUC 0.937; 95% CI 0.880-0.994, P < 0.001). CONCLUSIONS: The tissue perfusion index (TPI), PtcCO2, and PtcO2/ FiO2 can predict the severity and outcome of severe and critical COVID-19.

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.

Predictors of a Successful Outcome Following a Thoracic Erector Spinae Plane Block for Cervical Radiculopathy.

BACKGROUND: The erector spinae plane block (ESPB) is an interfascial plane block for managing neuropathic thoracic pain. Although the ESPB is applied widely in various clinical situations, no studies have evaluated the association between the analgesic outcomes of the ESPB and the numerical changes in the perfusion index (PI) and PI ratio. OBJECTIVES: The purpose of this study is to investigate the association between the clinical response following ESPB and other possible factors, including changes in the PI and PI ratio. STUDY DESIGN: A prospective, nonrandomized, and open-label study. SETTING: The pain clinic of a tertiary university hospital. METHODS: This study included 92 patients with neck or arm pain who received T2 ESPB using 20 mL of 0.2% ropivacaine. To aid in the prediction of clinical outcomes, the PI was measured at the blocked side for 30 minutes as soon as the ESPB was finished. Various demographic data were also analyzed to predict the clinical outcomes. RESULTS: Among 92 patients, 59 patients (64%) showed successful treatment outcomes (> 50% reduction in the numerical rating scale score or > 30% reduction in the neck disability index). The baseline PI of the responders was statistically higher than the nonresponders' (P < 0.05). Also, the responders' PI demonstrated statistically higher values than the nonresponders' at the time points of 4, 6, and 8 minutes after the ESPB. Multivariate logistic regression analysis revealed that a higher baseline PI (OR, 1.91; 95% CI, 1.27-2.86; P = 0.002) was an independent factor associated with a successful outcome. LIMITATIONS: Only a small number of patients with nonspinal diseases were included, except for those who had cervical radiculopathy. Therefore, it is hard to conclude that thoracic ESPB has any therapeutic benefits to patients with nonspinal diseases such as complex regional pain syndrome, adhesive capsulitis, or post-thoracotomy pain syndrome. CONCLUSION: A successful outcome at 4 weeks after T2 ESPB was achieved in 64% of patients with cervical radiculopathy. A higher baseline PI value was an independent factor associated with a successful response to T2 ESPB.

Evaluation of perfusion index as a predictor of successful caudal block in pediatric patients: A prospective randomized study.

Background and Aims: Caudal block is among the most widely administered regional anesthesia in pediatric patients. The clinical signs and objective assessments are not fast and reliable enough to provide a good feedback. Perfusion index (PI) is considered as a sensitive marker to assess the efficacy of caudal block. We aim to assess PI as an indicator for success of caudal block in pediatric patients. Material and Methods: Sixty pediatric patients scheduled for elective surgery of lower abdomen and below were included. Patients were randomly allocated into two groups (n = 30): Group 1 received caudal block after general anesthesia and Group 2 only received general anesthesia. PI, heart rate, mean arterial pressure, and anal sphincter tone (AST) were recorded at 5, 10, 15, and 20 min following induction of anesthesia. Results: A persistent increase in the PI value was observed in Group 1 starting from 5 min till 20 min, as compared to Group 2, at all the time intervals. When mean PI was statistically compared between both the groups, it was found to be highly significant (P = 0.001). Group 1 patients have progressive laxity of AST which was found to be significantly different from Group 2 (P < 0.001). Conclusion: We have found that both PI and AST are good indicators for assessing success of caudal block onset in pediatric patients but AST took slightly longer time (~20 mins). Therefore, we conclude that PI is simple, economical, and noninvasive monitor that predicts the caudal onset much earlier than AST.

Perfusion index to predict post spinal hypotension in lower segment caesarean section.

Background and Aims: It is important to predict and prevent post-spinal hypotension in lower segment cesarean section (LSCS). Peripheral vascular tone can be monitored as a perfusion index (PI) from a pulse oximeter. We aimed to study baseline PI as a predictor of post-spinal hypotension in LSCS. Material and Methods: Prospective observational study conducted in a tertiary care teaching public hospital on patients posted for elective LSCS under spinal anesthesia. Baseline PI and hypotension were compared. A receiver operating characteristic (ROC) curve was plotted and data were analyzed using SPSS version 20. Results: Among 90 females, 43 (47.8%) had a PI ≤3.5 and 47 (52.2%) had a PI >3.5. In the PI >3.5 group, 46 (97.9%) females had hypotension and required a high volume of IV fluids, and 29 (61.7%) required vasopressors, and the association with PI was statistically significant with Pearson's Chi-square values of 32.26 and 32.36, respectively (P = 0.001). In the ROC, the area under the curve (AUC) was 0.917, proving baseline PI >2.9 as an excellent classifier (P < 0.0001,95% confidence interval [CI] 0.840-0.965) and can predict hypotension with a sensitivity of 83.08% and specificity of 96.00%. Conclusion: Baseline PI >3.5 was associated with significant post-spinal hypotension and vasopressor administration in LSCS. We established baseline PI >2.9 can predict post-spinal hypotension with high sensitivity and specificity. PI is simple, quick, and non-invasive and can be used as a predictor for post-spinal hypotension in parturients undergoing LSCS so that prophylactic measures can be considered in at-risk patients for better maternal and fetal outcomes.

The Doppler Perfusion Index of the Liver and the Underlying Duplex Sonography of Visceral Vessels-A Systematic and Comprehensive Evaluation of Reproducibility.

Prior to the curative resection of colorectal carcinoma (CRC) or pancreatic ductal adenocarcinoma (PDAC), the exclusion of hepatic metastasis using cross-sectional imaging is mandatory. The Doppler perfusion index (DPI) of the liver is a promising method for detecting occult liver metastases, but the underlying visceral duplex sonography is critically viewed in terms of its reproducibility. The aim of this study was to investigate systematically the reproducibility of the measured variables, the calculated blood flow, and the DPI. Between February and September 2023, two examinations were performed on 80 subjects within a period of 0-30 days and at two previously defined quality levels, aligned to the German standards of the DEGUM. Correlation analyses were carried out using Pearson's correlation coefficient (PCC) and the intraclass correlation coefficient (ICC). The diameters, blood flow, and DPI showed a high degree of agreement (PCC of 0.9 and ICC of 0.9 for AHP). Provided that a precise standard of procedure is adhered to, the Doppler examination of AHC, AHP, and PV yields very reproducible blood flows and DPI, which is a prerequisite for a comprehensive investigation of its prognostic value for the prediction of metachronous hepatic metastasis in the context of curatively treated CRC or PDAC.

Comparison between perfusion index, pleth variability index, and pulse pressure variability for prediction of hypotension during major abdominal surgery under general anaesthesia: A prospective observational study.

Background and Aims: Short-term hypotension after general anaesthesia can negatively impact surgical outcomes. This study compared the predictive potential of the pleth variability index (PVI), pulse pressure variability (PPV), and perfusion index (PI) for anaesthesia-induced hypotension. This study's primary objective was to evaluate the predictive potential of PI, PVI, and PPV for hypotension. Methods: This observational study included 140 adult patients undergoing major abdominal surgery under general anaesthesia. Mean arterial pressure, heart rate, PVI, PPV, and PI were collected at 1-min intervals up to 20 min post anaesthesia induction. Hypotension was assessed at 5-min and 15-min intervals. Receiver operating characteristic (ROC) curves were plotted to determine the diagnostic performance and best cut-off for continuous variables in predicting a dichotomous outcome. Statistical significance was kept at P < 0.05. Results: Hypotension prevalence within 5 and 15 min of anaesthesia induction was 36.4% and 45%, respectively. A PI cut-off of <3.5 had an area under the ROC curve (AUROC) of 0.647 (P = 0.004) for a 5-min hypotension prediction. The PVI's AUROC was 0.717 (P = 0.001) at cut-off >11.5, while PPV's AUROC was 0.742 (P = 0.001) at cut-off >12.5. At 15 min, PVI's AUROC was 0.615 (95% confidence interval 0.521-0.708, P = 0.020), with 54.9% positive predictive value and 65.2% negative predictive value. Conclusion: PVI, PPV, and PI predicted hypotension within 5 min after general anaesthesia induction. PVI had comparatively higher accuracy, sensitivity, specificity, and positive predictive value than PI and PPV when predicting hypotension at 15 min.

Comparing Perfusion Index and Visual Analogue Scores for Postoperative Pain Assessment Following Upper Limb Surgeries Under Supraclavicular Brachial Plexus Block: An Observational Study.

BACKGROUND: Effective pain assessment is crucial to tailor the analgesic regimen post-operatively. Perfusion index (PI) has been reported to be a useful objective assessment tool for monitoring pain. This study aimed to explore the utility of PI in assessing postoperative pain in upper limb surgeries under supraclavicular block and its correlation with visual analogue scale (VAS) scores. METHODS: This prospective, observational study included 140 patients scheduled for elective upper limb surgeries. PI, VAS scores, heart rate (HR), mean arterial pressure (MAP) and physiological parameters were recorded at baseline and postoperatively. Inj. tramadol was administered when the VAS score exceeded ≥ 4 and the VAS score, PI, HR and MAP were recorded at 5, 10, 15 and 20 minutes after administration. Comparison of normally and non-normally distributed data was done using t-statistics and Mann-Whitney U-test respectively. Pearson correlation was used to establish a correlation between variables and the receiver operating characteristic (ROC) curve was used to calculate the cut-off value of PI to determine the onset of pain. RESULTS: There was a significant and moderate correlation between pre-analgesic and post-analgesic PI and VAS score (r = -0.425 and -0.448 respectively, p<0.001), while PI and MAP or PI and HR showed only a weak correlation. A cut-off value of 14.7 for PI showed 76.3% sensitivity and 100% specificity in predicting rescue analgesia requirements. CONCLUSION: The study supports the use of PI as an objective measure for postoperative pain assessment, with a notable correlation with VAS scores. The identified cut-off value for PI adds to its clinical utility in predicting the need for rescue analgesia.

Peripheral perfusion index stratifies risk in patients with intraoperative anemia: A multicentre cohort study.

STUDY OBJECTIVE: Evidence for red blood cell (RBC) transfusion thresholds in the intraoperative setting is limited, and current perioperative recommendations may not correspond with individual intraoperative physiological demands. Hemodynamics relevant for the decision to transfuse may include peripheral perfusion index (PPI). The objective of this prospective study was to assess the associations of PPI and hemoglobin levels with the risk of postoperative morbidity and mortality. DESIGN: Multicenter cohort study. SETTING: Bispebjerg and Hvidovre University Hospitals, Copenhagen, Denmark. PATIENTS: We included 741 patients who underwent acute high risk abdominal surgery or hip fracture surgery. INTERVENTIONS: No interventions were carried out. MEASUREMENTS: Principal values collected included measurements of peripheral perfusion index and hemoglobin values. METHODS: The study was conducted using prospectively obtained data on adults who underwent emergency high-risk surgery. Subjects were categorized into high vs. low subgroups stratified by pre-defined PPI levels (PPI: > 1.5 vs. < 1.5) and Hb levels (Hb: > 9.7 g/dL vs. < 9.7 g/dL). The study assessed mortality and severe postoperative complications within 90 days. MAIN RESULTS: We included 741 patients. 90-day mortality was 21% (n = 154), frequency of severe postoperative complications was 31% (n = 231). Patients with both low PPI and low Hb had the highest adjusted odds ratio for both 90-day severe postoperative complications (2.95, [1.62-5.45]) and 90-day mortality (3.13, [1.45-7.11]). A comparison of patients with low PPI and low Hb to those with high PPI and low Hb detected significantly higher 90-day mortality risk in the low PPI and low Hb group (OR 8.6, [1.57-162.10]). CONCLUSION: High PPI in acute surgical patients who also presents with anemia was associated with a significantly better outcome when compared with patients with both low PPI and anemia. PPI should therefore be further investigated as a potential parameter to guide intraoperative RBC transfusion therapy.

Evaluation of Hemodynamic Changes and Fluid Response during Anesthesia in Lumbar Disc Hernias with Pleth Variability Index (PVI).

The study aimed to assess the pleth variability index (PVI) in patients undergoing lumbar disc herniation surgery under general and spinal anesthesia, exploring its correlation with fluid responsiveness, position, and hemodynamic parameters. Methods: This prospective study included 88 ASA 1-2 patients, aged 18-65, undergoing 1-3 h elective lumbar disc herniation surgery. Patients in groups GA and SA were observed for demographic, operative, and hemodynamic parameters at specified time points. (3) Results: PVI values were comparable between the GA and SA groups. After 250 mL of fluid loading, both groups showed a significant decrease in basal PVI at T2. Prone positions in GA exhibited higher PI values than in SA. The transition from a prone to supine position maintained PVI, while pulse and MAP decreased.; (4) Conclusions: PVI values were comparable in elective lumbar disc herniation surgery with general and spinal anesthesia. Both groups exhibited significant a PVI decrease at T2 after 250 mL of fluid loading, indicating fluid responsiveness. In general anesthesia, the prone position showed a lower MAP and higher PI values compared to spinal anesthesia. PVI and PI, sensitive to general anesthesia changes, could have beneficial additions to standard hemodynamic monitoring in spinal anesthesia management.

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).

The diagnostic accuracy of preoperative perfusion index as a predictor of postspinal anesthesia hypotension in parturients undergoing cesarean delivery: A prospective non-blinded observational study.

Background and Objectives: Spinal anesthesia is the technique of choice for elective cesarean section with a prominent side effect of postspinal anesthesia hypotension (PSH). This needs an early prediction to avoid feto-maternal complication. This study aimed to assess the diagnostic accuracy of perfusion index (PI) and inferior vena cava collapsibility index (IVCCI) in the prediction of PSH. Material and Methods: Thirty parturients of American Society of Anesthesiologists Physical Status (ASA-PS) 1 and two undergoing cesarean delivery participated in the study. IVCCI, PI, baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and heart rate (HR) were noted in the preoperative period. The fall of MBP by 20% from baseline or below 65 mm Hg was considered PSH. After spinal anesthesia, SBP, DBP, MBP, and HR were noted again for diagnosing PSH. Results: It did not show any statistical difference when comparing the PI between the PSH and non-PSH groups in both the PSH definition groups. IVCCI was significantly higher when PSH was considered MBP <65 mm Hg (P = 0.01). However, IVCCI was found to be statistically insignificant if PSH was considered a 20% reduction in baseline MBP. The correlation matrix between IVCCI and PI showed Pearson's r-value of 0.525, indicating a substantial relationship between the two (P = 0.003). Multivariate logistic regression analysis had shown that neither IVCCI nor PI was a good predictor of PSH in parturients for both definition groups for PSH. Conclusion: Although there is a modest correlation between PI and IVCCI, both cannot be used to predict postspinal hypotension in parturients undergoing elective lower-segment cesarean section (LSCS).