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.

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.

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.

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).

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.

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.

A low peripheral perfusion index can accurately detect prolonged capillary refill time during general anesthesia: A prospective observational study.

Background: Capillary refill time (CRT) is the gold standard for evaluating peripheral organ perfusion; however, intraoperative CRT measurement is rarely used because it cannot be conducted continuously, and it is difficult to perform during general anesthesia. The peripheral perfusion index (PI) is another noninvasive method for evaluating peripheral perfusion. The PI can easily and continuously evaluate peripheral perfusion and could be an alternative to CRT for use during general anesthesia. This study aimed to determine the cutoff PI value for low peripheral perfusion status (prolonged CRT) by exploring the relationship between CRT and the PI during general anesthesia. Methods: We enrolled 127 surgical patients. CRT and the PI were measured in a hemodynamically stable state during general anesthesia. A CRT >3 s indicated a low perfusion status. Results: Prolonged CRT was observed in 27 patients. The median PI values in the non-prolonged and prolonged CRT groups were 5.0 (3.3-7.9) and 1.5 (1.2-1.9), respectively. There was a strong negative correlation between the PI and CRT (r = -0.706). The area under the receiver operating characteristic curve generated for the PI was 0.989 (95% confidence interval, 0.976-1.0). The cutoff PI value for detecting a prolonged CRT was 1.8. Conclusion: A PI <1.8 could accurately predict a low perfusion status during general anesthesia in the operating room. A PI <1.8 could be used to alert the possibility of a low perfusion status in the operating room. Trial Registration: University Hospital Medical Information Network (UMIN000043707; retrospectively registered on March 22, 2021, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno = R000049905).

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.

Changes of peripheral perfusion index in very low birth weight infants with late-onset sepsis / 中国小儿急救医学

Objective:To analyze the changes of peripheral perfusion index (PPI) with late-onset sepsis (LOS) in very low birth weight infants during hospitalization.Methods:Very low birth weight infants admitted to the neonatal intensive care unit of Children′s Hospital of Fudan University from August 1, 2021 to August 31, 2022 were consecutively included.Infants with admission age ≥three days and unstable circulation, or positive blood culture within three days after birth were excluded.From the day of admission, the PPI values of the right hand and either foot of the infants were measured with Masimo SET Radical-7 everyday while whether LOS occurred during hospitalization was observed.The mean PPI curve of very and extremely low birth weight infants without LOS was plotted.For those with LOS confirmed by blood culture, the PPI change trajectory three days before and after the occurrence of LOS was drawn, and the change trend of PPI before the occurrence of LOS was analyzed by trend chi-square test.Non-parametric test was used to analyze the effect of LOS on pre- and post-ductal PPI values.Results:A total of 107 very low birth weight infants were included in the final analysis.Among them, there were 11 infants confirmed as LOS by blood culture, 37 infants diagnosed as clinical LOS, and 59 infants without LOS.Pre-and post-ductal PPI values of very low birth weight infants without LOS were 2.06±1.30 and 1.72±0.92, respectively; those with clinical LOS were 1.90±0.94 and 1.58±0.83, respectively; those with LOS confirmed by blood culture were 1.92±1.11 and 1.62±0.82, respectively.For infants with LOS confirmed by blood culture, the pre-and post-ductal PPI values showed a continuous downward trend during three days before the onset of disease, with the lowest PPI values on the first day before the diagnosis of blood culture.The downtrend of pre-ductal PPI was statistically significant ( χtrend2=5.57, P<0.05). Conclusion:The PPI value of very low birth weight infants show a downward trend when LOS occurs.It should be observed dynamically in clinical practice, which is helpful to suspect or identify LOS as early as possible.

Effect of perioperative magnesium sulfate and labetalol infusion on peripheral perfusion and postoperative pain in nasal surgery: a randomized controlled trial.

BACKGROUND: Maintenance of adequate peripheral perfusion during controlled hypotension is necessary for patient safety and improved surgical outcomes during controlled hypotension in nasal surgery. The hypothesis of this study was to investigate the effect of perioperative magnesium sulfate and labetalol infusion on peripheral perfusion and postoperative pain in patients undergoing nasal surgery. METHODS: A total of 50 patients were randomly assigned into two equal groups in this double-blind clinical study: the magnesium sulfate group; received 40 mg/kg loading dose of intravenous (IV) magnesium sulfate followed by 10-15 mg/kg/h continuous IV infusion and the labetalol group; received 0.25 mg/kg loading dose of IV labetalol followed by 0.5-1 mg/kg/h continuous IV infusion to achieve a mean arterial blood pressure (MABP) of = 55-65 mmHg. The primary outcome was to compare the effect of perioperative magnesium sulfate and labetalol infusion on peripheral perfusion during nasal surgery. The secondary outcomes were the assessment of serum lactate, postoperative pain, time to the first call for pethidine (rescue analgesic) and total pethidine consumption. RESULTS: PPI was comparable between the groups at baseline, intubation, and 5 min. In contrast, magnesium sulfate group had a significantly higher PPI than the labetalol group. The magnesium sulfate group had a significantly higher MABP and heart rate compared to labetalol group. The time to reach the target MABP was significantly prolonged in magnesium sulfate than the labetalol group [21.6 ± 1.7 vs 6.9 ± 1.5] min. VAS scores were significantly lower for 2 hs postoperatively in the magnesium sulfate group than the labetalol group. The time to first call of pethidine was significantly prolonged in the magnesium sulfate group compared to the labetalol group [113.1 ± 5.2 vs 28.2 ± 1.5] min. CONCLUSIONS: Magnesium sulfate maintains wider PPI and offers better postoperative pain relief compared to labetalol during induced hypotension in nasal surgery. TRIAL REGISTRATION: Institutional review board approval (ref: 6601/20-12-2020). CLINICALTRIAL: gov (ref: NCT04688203 , date of registration: 29 -12-2020).

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.

Clinical study of fluid resuscitation guided by peripheral perfusion index in patients with septic shock / 中华危重病急救医学

Objective:To explore the guiding effect of peripheral perfusion index (PI) on fluid resuscitation in patients with septic shock.Methods:Sixty-five patients with septic shock who were diagnosed according to relevant criteria of septic shock and admitted to the department of critical care medicine of the Affiliated Hospital of Hangzhou Normal University from September 2017 to December 2020 were included. Patients were divided into the conventional treatment group (30 cases) and PI guidance group (35 cases) by random number method. Both groups of patients were treated with the bundle according to clinical guidelines. Sputum, urine and blood were collected for pathogenic microorganism culture before the application of antibiotics, and vasoactive drugs were given. Both groups need to achieve all the following resuscitation goals within 6 hours: urine output > 0.5 mL·kg -1·h -1, mean arterial pressure (MAP) ≥ 65 mmHg (1 mmHg ≈ 0.133 kPa), central venous pressure (CVP) was 8-12 mmHg, and central venous oxygen saturation (ScvO 2) ≥ 0.70. There was no further resuscitation in the conventional treatment group after the goals were achieved. In addition to these four goals, the PI guidance group was expected to achieve PI≥ 1.4. Heart rate (HR), CVP, MAP, ScvO 2, blood lactic acid (Lac), the time of fluid negative balance, intensive care unit (ICU) mortality and 28-day mortality between the two groups were compared before and after 6 hours of fluid resuscitation. Results:Before fluid resuscitation, there were no statistically significant differences in all indicators between two groups. After 6 hours fluid resuscitation, the four treatment goals in PI guidance group were slightly lower than those of the conventional treatment group [HR (times/min): 96.5±12.1 vs. 97.7±7.9, MAP (mmHg): 83.2±6.2 vs. 82.1±7.5, ScvO 2: 0.661±0.077 vs. 0.649±0.051, CVP (mmHg): 10.8±2.7 vs. 10.4±2.1], there were no statistically significant differences between the two groups (all P > 0.05); the Lac level of the PI guidance group after resuscitation was lower than that of the conventional treatment group, and the difference was statistically significant (mmol/L: 4.8±1.3 vs. 5.9±1.4, P < 0.05); the duration of fluid negative balance in the PI guidance group was earlier than that in the conventional treatment group [days: 3.0 (2.0, 3.0) vs. 3.5 (3.0, 4.0), P < 0.05]. The ICU mortality and 28-day mortality in the PI guidance group were lower than those in the conventional treatment group [ICU mortality rate: 37.1% (13/35) vs. 50.0% (15/30), 28-day mortality rate: 57.1% (20/35) vs. 60.0% (18/30)], but the differences were not statistically significant (both P > 0.05). Conclusions:The peripheral PI can be used as an important indicator of fluid resuscitation in patients with septic shock. PI guiding fluid resuscitation in patients with septic shock can reduce Lac levels, shorten the duration of fluid negative balance and reduce the risk of fluid overload.

The prognostic value of PI combined with Pv-aCO 2 /Ca-vO 2 in patients with septic shock / 中华急诊医学杂志

Objective:To explore the predictive value of peripheral perfusion index (PI) combined with central venous-arterial carbon dioxide tension to arterial-venous oxygen content ratio(Pv-aCO 2/Ca-vO 2)for prognosis after initial resuscitation of septic shock. Methods:A total of 76 cases of patients with septic shock from January 2019 to January 2021 in emergency intensive care unit (EICU) of Harrson international peace hospital affiliated to Hebei Medical University were enrolled. All recovered according to 2016 Severe Sepsis and Septic Shock Treatment International Guidelines 2016 (SSC 2016) , and PI was monitored, central vein and arterial blood gas analysis was performed, and the ratio of Pv-aCO 2/Ca-vO 2 was calculated.The PI and Pv-aCO 2/Ca-vO 2 at 3 h,hemodynamic variables,oxygen metabolism indexes,APACHEⅡ and SOFA score were recorded.Patients were divided into survival group and death group according to 28 d survival condition, the dfferences in demographics and clinical data were compared between two groups.The Kaplan-Meier urviving curve was created and the survival of the patients was analyzed by the Log-rank test. Risk factors associated with the prognosis were analyzed using the Cox regression analysis. The role of PI and Pv-aCO 2/Ca-vO 2 in prediting death was evaluated by receiver operating characteristic curves(ROC). Results:There were 37 cases in survival group and 39 cases in death group.Compared with death group, PI in survival group [(1.77±0.63) vs. (0.89±0.69)]was significantly higher,and Pv-aCO 2/Ca-vO 2[(1.52±0.52) vs. (2.57±0.86)] was significantly lower ( P<0.05). Kaplan-Meier survival curve showed that the median survival time in the high PI group [20.09 d (95% CI:16.95-23.24) vs.11.00d (95% CI:7.14-14.86)] was longer than that in the low PI group(χ 2=12.424, P=0.000),and that in low Pv-aCO 2/Ca-vO 2 group [23.74 d (95% CI:20.35-27.13) vs.12.85d (95% CI:9.75-15.95)] was longer than that in the high Pv-aCO 2/Ca-vO 2 group (χ 2=12.200, P=0.000) .Cox regression analysis showed that both PI ( RR=0.397, 95% CI: 0.230-0.687, P =0.001) and Pv-aCO 2/Ca-vO 2 ( RR=1.878, 95% CI: 1.169-3.019, P =0.009) were predictors of 28 d mortality.The area under the ROC curve of PI and Pv-aCO 2/Ca-vO 2 for predicting 28 d death in patients with septic shock were 0.828 (95% CI: 0.732-0.923) and 0.785 (95% CI: 0.6777-0.893)respectively. The optimal cutoff values were 0.52 (sensitivity 58.3% and specificity 94.4%) and 0.35 (sensitivity 88.9% and specificity 63.9%)respectively, and the AUC of the combined prediction of the two indicators was 0.903 (95% CI: 0.835-0.971). Conclusions:Combination of PI and Pv-aCO 2/Ca-vO 2 is better to predict the risk of adverse outcomes of septie shock patients,and may provide useful information for the resuscitation at early stage.

Application of peripheral perfusion index in the screening of congenital heart disease in neonates / 中国小儿急救医学

Congenital heart disease (CHD) is the most common congenital malformations, and critical CHD is one of the main causes of neonatal death and poor prognosis.Early screening and detection of congenital heart disease in newborns is helpful to early intervention and improve prognosis.At present, pulse oximetry alone, pulse oximetry combined with physical examination or pulse oximetry combined with cardiac murmur auscultation in early postnatal screening can detect most of critical CHD, but there are still some false negative results.Peripheral perfusion index (PPI) may have a certain value in finding left ventricular obstructive CHD that can not be found in the current screening methods.Therefore, this review summarized the technical principle and influence factors of PPI, its feasibility and effectiveness in neonatal CHD screening, and the possible threshold of screening, in order to provide a certain basis for PPI screening of neonatal CHD in the future.

Plethysmographic Peripheral Perfusion Index: Could It Be a New Vital Sign?

The plethysmographic peripheral perfusion index (PPI) is a very useful parameter with various emerging utilities in medical practice. The PPI represents the ratio between pulsatile and non-pulsatile portions in peripheral circulation and is mainly affected by two main determinants: cardiac output and balance between sympathetic and parasympathetic nervous systems. The PPI decreases in cases of sympathetic predominance and/or low cardiac output states; therefore, it is a useful predictor of patient outcomes in critical care units. The PPI could be a surrogate for cardiac output in tests for fluid responsiveness, as an objective measure of pain especially in un-cooperative patients, and as a predictor of successful weaning from mechanical ventilation. The PPI is simple to measure, easy to interpret, and has continuously displayed variables, making it a convenient parameter for detecting the adequacy of blood flow and sympathetic-parasympathetic balance.

Acute hyperventilation increases oxygen consumption and decreases peripheral tissue perfusion in critically ill patients.

PURPOSE: This study aimed to evaluate the effects of acute hyperventilation on central venous-to-arterial carbon dioxide tension difference (Pv-aCO2), central venous oxygen saturation (ScvO2), central venous-to-arterial CO2 difference/arterial-central venous O2 difference ratio (CO2GAP-Ratio), and peripheral perfusion index (PI) in hemodynamically stable critically ill patients. METHODS: Fifty-four mechanically ventilated patients were evaluated. The cardiac index, Pv-aCO2, ScvO2, CO2GAP-Ratio, PI, and arterial and venous blood gas parameters were measured in the first set of measurements. Then, alveolar ventilation was increased by raising the respiratory rate (10 breaths/min). After a 30 min hyperventilation period, the second set of measurements was recorded. RESULTS: Acute hyperventilation induces an increase in Pv-aCO2 (from 3.87 ± 1.31 to 8.44 ± 1.81 mmHg, P < 0.001) and a decrease in ScvO2(from 71.78 ± 4.82 to 66.47 ± 5.74%, P < 0.001). The CO2GAP-Ratio was significantly increased(from 0.97 ± 0.40 to 1.74 ± 0.46, P < 0.001), and the PI showed a remarkable decrease caused by acute hyperventilation(from 1.82 ± 1.14 to 1.40 ± 0.99，P = 0.04). Hyperventilation-induced ∆_Pv-aCO2 was negatively correlated with ∆PaCO2(r = -0.572, P<0.001). The change in ∆_PaCO2 was correlated with ∆_ScvO2(r = 0.450, P<0.001). However, the left ventricular outflow tract velocity time integral (LVOT-VTI) remained unchanged during hyperventilation. CONCLUSIONS: Acute hyperventilation induced an increase in oxygen consumption and decreased peripheral tissue perfusion in patients. For critical care patients, it is necessary to pay attention to the influence of hyperventilation on peripheral tissue perfusion indices and oxygen consumption indices.