Assessment of pulse oximeter perfusion index in pediatric caudal block under basal ketamine anesthesia

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.

Predictive Ability of Perfusion Index for Determining the Success of Adductor Canal Nerve Block for Postoperative Analgesia in Patients Undergoing Unilateral Total Knee Arthroplasty

BACKGROUND

The perfusion index (PI) is an objective method used to determine a successful nerve block. This study aimed to investigate the prognostic ability of the PI for a successful adductor canal nerve block (ACB) and suggest the optimal PI cut-off value for predicting a block.

METHODS

This study was a prospective observational study and enrolled a total of 39 patients. The patients were dichotomized into successful and inappropriate ACB groups according to the results of the sensation tests. The PI value, Pleth variability index (PVi) value, and heart rate were recorded one minute before the block, at the time of the block, and one to 30 min after the block at one-minute intervals. Delta (dPI), which was defined as the difference in PI value from the baseline (the value one minute before the block), was the primary outcome. The area under the receiver operating characteristic curve (AUROC) was calculated to determine the dPI prognostic accuracy and optimal cut-off value.

RESULTS

Successful ACB was achieved in 33 patients, while ACB was inappropriate in six patients. The dPI showed significant differences between the two groups under the time interval measured (p = 0.001). The dPI at 5 and 20 min showed good prognostic ability for a successful block, with optimal cut-off values of 0.33 (AUROC: 0.725, 95% CI 0.499-0.951) and 0.64 (AUROC: 0.813, 95% CI 0.599-1.000), respectively.

CONCLUSIONS

The dPI is an effective predictor of successful ACB. The suggested dPI cut-off values at 5 and 20 min were below 0.33 and 0.64, respectively.

Evaluation and correlation of nociceptive response index and spectral entropy indices as monitors of nociception in anesthetized patients

Objectives

During anesthesia, the response to these stimuli depends on the balance between nociception and antinociception. Recently, various monitoring systems based on the variables derived from electroencephalography, plethysmography, autonomic tone, reflex pathways, and composite algorithms have been introduced for monitoring nociception. The main aim of our study was to evaluate and correlate the physiological variables which reflect the autonomic nervous system response to nociception, such as heart rate (HR), systolic blood pressure (SBP), perfusion index (PI), and nociceptive response index (NRI), with the spectral entropy indices response entropy (RE) and RE-state entropy (SE), which reflects electromyographic (EMG) activation as a response to pain.

Materials and Methods

This is a retrospective analysis of the data from a prospective study on the hypnotic and analgesic effects and the recovery profile of sevoflurane-based general anesthesia. Eighty-six patients undergoing single-agent sevoflurane anesthesia were recruited in the study. The study parameters, HR, SBP, SE, RE, RE-SE, PI, and NRI, were recorded at predefined time points before and after a standardized noxious stimulus. Correlation between the variables was carried out by applying the Pearson correlation equation for normal and the Spearman correlation equation for non-normally distributed data. Receiver operating characteristic (ROC) graphs were plotted, and the area under the curve was calculated to assess the diagnostic accuracy of post-stimulus NRI in detecting pain which was defined as RE-SE >10.

Results

There was a significant increase in the SBP, HR, NRI, RE, SE, and RE-SE and a considerable decrease in PI values during the post-noxious period compared to the pre-noxious period. There was no correlation between the absolute values of NRI and entropy indices at T2. However, among the reaction values, there was a weak correlation between the reaction values of NRI and RE (r = 0.30; P = 0.05). The area under the ROC curve for NRI to detect pain as defined by RE-SE >10 was 0.56.

Conclusion

During sevoflurane anesthesia, the application of noxious stimulus causes significant changes in variables reflecting sympathetic response and EMG activity. However, NRI failed to detect nociception, and there was only a weak correlation between the reaction values of NRI and RE-SE.

Perfusion index for early identification of regional anesthesia effectiveness: a narrative review

Regional anesthesia (RA) is a common and irreplaceable technique in clinical, which can be used in different surgery sites and control of acute and chronic pain, especially for outpatients, pediatrics and the elderly. RA demands are increasing during COVID-19 pandemic because many surgeries could be performed under RA to reduce the risk of cross-infection between patients and health care workers. Early and accurate identification of the effects of RA can help physicians make timely decisions about whether to supplement analgesics or switch to general anesthesia, which will save time and improve patient satisfaction in a busy operating room. Perfusion index (PI) is a parameter derived from photoplethysmography (PPG) and represents the ratio of pulsatile and non-pulsatile blood flow at monitoring sites. It reflects local perfusion and is mainly affected by stroke volume and vascular tone. With characteristics of non-invasive, rapid, simple, and objective, PI is widely used in clinical practice, such as fluid responsiveness prediction, nociceptive assessment, etc. Recently, many studies have assessed the accuracy of PI in early prediction of RA success, including brachial plexus block, sciatic nerve block, neuraxial anesthesia, paravertebral block, caudal block and stellate ganglion block. Successful RA often parallels increased PI. In this narrative review, we describe the principles and influencing factors of PI, and introduce the effects of PI on early identification of RA effectiveness.

Evaluation of prediction effect of perfusion index for supraclavicular brachial plexus block in children: protocol for a randomized trial

Background

Pulse perfusion index (PI) reflects blood perfusion. It has been reported that PI can be used to evaluate the effect of nerve block, but currently, it is mainly focused on awake adults. In pediatric general anesthesia, it has been reported that PI can evaluate the effect of the sacral block. Still, there is a lack of relevant research on the impact of brachial plexus blocks. Our objective is to assess the prediction effects of PI on the success of supraclavicular brachial plexus block in pediatric patients under sevoflurane or propofol general anesthesia.

Methods/design

This is a mono-center, parallel, 2-arm randomized superiority trial. One hundred four children aged 1 month to 12 years who undergo upper limb surgery will be enrolled in this study. According to anesthesia induction and maintenance medication, they will be divided into sevoflurane and propofol groups. The PI values of the index and little finger will be recorded on the blocked and non-blocked sides of supraclavicular brachial plexus block (SCB) in all children. The primary outcome is to assess the effects of PI on the success of supraclavicular brachial plexus block in pediatric patients under sevoflurane or propofol general anesthesia. The secondary outcome includes mean arterial blood pressure (MAP), heart rate (HR), and correlation between baseline PI and 10 min after SCB (PI ratio).

Discussion

This trial will provide evidence on the changes in PI after SCB in sevoflurane or propofol anesthesia in children. SCB may lead to changes in PI values under sevoflurane or propofol anesthesia. After the children wake up at the end of the surgery, the changes in PI values on the block side and non-block side may be helpful to judge the effect of nerve block when excluding the influence of anesthetics.

Trial registration

ClinicalTrials.gov NCT04216823. Registered on 15 July 2020.

The perfusion index could early predict a nerve block success: A preliminary report

Introduction:

In literature, there is plenty of material regarding regional anesthesia techniques and block safety, but lacks about block success prevision. The perfusion index (PI) is an oximetry reliability indicator, available on many monitors as non-invasive parameter, indicating the ratio of arterial blood flow (pulsatile flow) to venous, capillary, and tissue blood flow (non-pulsatile blood flow). We hypothesized that that analysis of PI variations after performing regional anesthesia could have a role in predicting a successful nerve block.

Methods:

Twenty-four consecutive patients regularly scheduled for limb surgery in regional anesthesia were included in our observation. PI measurements were recorded before regional anesthesia, and 1, 2, 3, 5, and 10 min after needle withdrawal. Along with PI, also sensation to cold (ice test), tactile sensation, and motor function were recorded before regional anesthesia, and 1, 2, 3, 5, and 10 min after needle withdrawal on the limb where the block were performed.

Results:

Ten sciatic nerve blocks, 6 spinal anesthesia, 8 brachial plexus block were performed and resulted successful. In all cases, PI values tripled at 5 min after the block execution and increased linearly, reaching at 10 min an average PI value 3.8 times higher for the interscalene group, 4 times for the spinal group, and 8 for the sciatic group.

Conclusions:

A tripled PI within 5 min from performing regional anesthesia showed to be a reliable indicator of nerve block success, but a bigger trial involving more patients and different anesthetic concentrations may be necessary to confirm this assumption.

The effect of epinephrine on the perfusion index during ultrasound-guided supraclavicular brachial plexus block: a randomized controlled trial

The perfusion index (PI) is an objective tool used to assess a successful nerve block. Epinephrine is a widely used adjuvant to local anesthetics, and it may affect PI values because of the vasoconstrictive property. The aim of this study was to investigate the influence of epinephrine on PI as an indicator of a successful block in ultrasound-guided supraclavicular brachial plexus block (SCBPB). In this randomized controlled trial, 82 adult patients underwent upper limb surgery under SCBPB were recruited between July 2018 and March 2019 in a single tertiary care center. Participants were randomly assigned to one of two groups: non-epinephrine group (n = 41) or epinephrine group (5 mcg ml⁻¹, n = 41). The primary outcome was the comparison of the “PI ratio 10,” which was defined as the ratio of the PI 10 to the baseline. Receiver operating characteristic (ROC) curves were constructed to determine the accuracy of the PI in predicting the block success at each time interval. The PI ratio 10 was 2.7 (1.9–4.0) in non-epinephrine group and 3.3 (2.2–4.4) in epinephrine group (median difference: 0.4; 95% confidence interval [CI] − 1.1 to 0.2; P = 0.207). The ROC curves compared without group identification were not significantly different over time. The cut-off value for the PI and PI ratio at 5 min (PI ratio 5) were 7.7 (area under the ROC [AUROC]: 0.89, 95% CI 0.83–0.94) and 1.6 (AUROC: 0.94, 95% CI 0.90–0.98), respectively. The perineural epinephrine did not affect the PI following a SCBPB. The PI ratio 5 > 1.6 might be considered as a relatively accurate predictor of a successful SCBPB.

Trial registration: This study was registered at the Clinical Trial Registry of Korea (https://cris.nih.go.kr. CriS No. KCT0003006).

Caudal Anesthesia for Pediatric Subumbilical Surgery, Less Load on the Postoperative Recovery Unit

Introduction

Caudal epidural anesthesia, when used as a sole method for surgical anesthesia, has favorable effects on the recovery duration and the time spent in the recovery unit. In this study we made a retrospective analysis of pediatric surgery operations under local, regional and general anesthesia. We aimed to find shorter postoperative recovery times with local and regional anesthesia.

Materials and methods

Data of the pediatric patients undergone subumbilical surgery during the two-year period in Pediatric Surgery clinic were collected. The patients’ age, sex, surgery type, anesthesia and airway control routes, as well as duration of anesthesia, operation and recovery were obtained.

Results

Data of 937 patients were analyzed, of whom 811 (86.6%) were males. Caudal anesthesia was performed in 240 patients (25.6%) and the mean age of these patients was 3.83 ± 3.00 years. The patients with caudal and local anesthesia spent significantly less time in the postoperative recovery unit, compared with general anesthesia groups (P < 0.001).

Conclusion

Caudal anesthesia as a sole method for pediatric subumbilical surgery is a relatively safe method. Patients having operation under caudal anesthesia have faster discharge times from postoperative recovery units, compared with general anesthesia. This probably reduces recovery unit expenditures.

Neurotoxicity versus Neuroprotection of Anesthetics: Young Children on the Ropes?

Normal brain development in young children depends on a balance between excitation and inhibition of neurons, and alterations to this balance may cause apoptosis. During the perioperative period, both surgical stimuli and anesthetics can induce neurotoxicity. This article attempts to expand the perspective of a topical issue-anesthetic-induced neurotoxicity-by also considering the protective effect of general anesthetics against surgery-induced neurotoxicity, all of which may generate some controversy in the current literature. The "new" major factor influencing neurotoxicity-nociceptive stimulus-is discussed together with other factors to develop clinical and research strategies to obtain a balance between neurotoxicity and neuroprotection.

The Predictive Value of Pulse Oximeters for Pulse Improvement after Angiography in Infants and Children

Background

Information from pulse oximeter waves confirms the presence of a pulse and helps obtain waves from tissue when the supplying artery is not readily accessible.

Objectives

This study determined the predictive value of pulse oximeters for detecting improved arterial pulses after angiography.

Patients and Methods

This cross-sectional, multi-center study included 467 4-day-old to 12-year-old patients and was conducted from January 2012 to January 2016. Angiographies were performed on 12-year-old or younger children for various medical reasons using venous, arterial, or both types of paths. The posterior malleolar or dorsalis pedis were palpated in punctured lower extremities. In the absence of a pulse, pulse oximetry was performed to identify pulse curves at 1 hour, 6 hours, and 12 hours after each angiography.

Results

Pulse oximetry displayed the pulses of 319 patients immediately following each angiography. Of these, 262 patients had palpable pulses at 6 hours after angiography (P < 0.0001), while 57 patients had no palpable pulse. Of these 57 patients, 15 had no palpable pulse at 12 hours after angiography (P < 0.0001). The odds of pulse improvement in children 6 hours after catheter angiography were 76% for the arterial path, 90% for the venous path, and 83.2% for both paths. At 12 hours after catheter angiography, these values increased to 91.6% for the arterial path, 100% for the venous path, and 95.9% for both paths.

Conclusions

The pulse oximeter can display the pulse curve immediately (1 hour) after angiography and indicate pulse improvement at 12 hours maximally following an angiography. In this case, heparin alone may be used instead of thrombolytic agents.

Ketamine: Current applications in anesthesia, pain, and critical care

Ketamine was introduced commercially in 1970 with the manufacturer's description as a "rapidly acting, nonbarbiturate general anesthetic" and a suggestion that it would be useful for short procedures. With the help of its old unique pharmacological properties and newly found beneficial clinical properties, ketamine has survived the strong winds of time, and it currently has a wide variety of clinical applications. It's newly found neuroprotective, antiinflammatory and antitumor effects, and the finding of the usefulness of low dose ketamine regimens have helped to widen the clinical application profile of ketamine. The present article attempts to review the current useful applications of ketamine in anesthesia, pain and critical care. It is based on scientific evidence gathered from textbooks, journals, and electronic databases.