A Cross-Sectional Study on the Agreement of Perfusion Indexes Measured on Different Fingers by a Portable Pulse Oximeter in Healthy Adults

Effectiveness of Perfusion Index ratio and End-Diastolic Velocity ratio in evaluating the efficacy of Interscalene Brachial Plexus Block: a prospective observational study

Objective

There is a lack of reliable indicators for evaluating the success of ultrasound-guided Interscalene Brachial Plexus Block (ISBPB). This study investigates the effectiveness of Perfusion Index (PI) ratio and End-Diastolic Velocity (EDV) ratio for early assessment of ISBPB effects.

Methods

Eighty-nine patients, aged 18-65 with BMI 18-24 kg/m2 and ASA grade I or II, underwent elective unilateral shoulder arthroscopic surgery. They received ultrasound-guided ISBPB with 15 mL local anesthetic (10 mL ropivacaine, 5 mL lidocaine). Patients were categorized into successful and failure groups based on needle test results after 30 min. PI and EDV of the brachial artery were recorded at baseline and at 5, 10, 15, 20, 25, and 30 min post-block. PI and EDV ratios were calculated by dividing values at each time by baseline. ROC curves were plotted at 5 and 10 min, and AUROC with 95% CI was calculated to assess block efficacy.

Results

Of 89 patients, 3 were excluded due to data loss and 2 withdrew, leaving 84 patients. Of these, 70 (83.3%) had successful blocks. In the successful group, both PI and EDV ratios on the blocked side significantly increased 5 min after the procedure. The PI ratio at 5 min had an AUROC of 0.894 (95% CI: 0.816-0.972), with a threshold of 1.22, sensitivity of 84.3%, and specificity of 85.7%. The EDV ratio had an AUROC of 0.706 (95% CI: 0.553-0.860), with a threshold of 1.32, sensitivity of 92.9%, and specificity of 50%. At 10 min, the PI ratio for assessing ISBPB impact had an AUROC of 0.901 (95% CI: 0.828-0.974), with a threshold of 1.4, sensitivity of 74.3%, and specificity of 92.9%. The AUROC for the EDV ratio was 0.799 (95% CI: 0.6788-0.921) with a threshold of 1.54, sensitivity of 92.9%, and specificity of 57.1%. The PI ratio at 5 min had a significantly higher AUROC than the EDV ratio, but no significant difference was found between PI ratios at 5 and 10 min.

Conclusion

Both PI ratio and EDV ratio assess ISBPB efficacy. The PI ratio provides a more precise evaluation, with optimal assessment at 5 min post-procedure.

Clinical trial registration

Chinese Clinical Trial Registry: ChiCTR2200066874.

A physiotherapy protocol* for stroke patients in acute hospital settings: expert consensus from the Brazilian early stroke rehabilitation task force

The present protocol provides general recommendations based on the best evidence currently available for physiotherapists to use as a guide for the care of stroke patients during hospitalization. The Brazilian Early Stroke Rehabilitation Task Force, comprising physical therapy experts and researchers from different Brazilian states, was organized to develop this care protocol based on a bibliographical survey, including meta-analyses, systematic reviews, clinical trials, and other more recent and relevant scientific publications. Professionals working in stroke units were also included in the task force to ensure the practicality of the protocol in different contexts. This protocol provides guidance on assessment strategies, safety criteria for the mobilization of patients with stroke, recommendations for mobilization and proper positioning, as well as evidence-based practices for treatment during hospitalization, including preventive measures for shoulder pain and shoulder-hand syndrome. The protocol also provides information on the organization of the physiotherapy service at stroke units, guidelines for hospital discharge, and quality indicators for physiotherapy services. We have included detailed activities that can be performed during mobilization in the supplementary material, such as postural control training, sensory and perceptual stimulation, task-oriented training, and activities involving an enriched environment. The protocol was written in a user-friendly format to facilitate its application in different social and cultural contexts, utilizing resources readily available in most clinical settings.

Relationship Between Finger Photoplethysmographic Pulses and Skin Blood Perfusion

Introduction Photoplethysmography (PPG) measures are important in monitoring peripheral oxygen saturation (SpO2). Another parameter is a derived quantity referred to as the peripheral perfusion index (PPI). It is calculated as the ratio of the peak-to-peak pulse amplitude of a PPG signal (PAPPG) to the non-pulsating part of the total PPG signal. The PPI has been used as a marker of blood perfusion states in a variety of clinical settings but has not been systematically and directly compared to measures of local blood perfusion. This study's purpose was to investigate this issue to provide initial data on the relationship between finger skin blood perfusion, measured by laser Doppler blood perfusion flux (LDF) and PAPPG. Methods Ten subjects (five male), recruited from medical students with an average age of 26 years, participated. While supine for 30 minutes, skin blood perfusion was recorded using laser Doppler flux (LDF) on the ring finger pulp of the non-dominant hand, and the photoplethysmography pulse (PPG) was recorded from the index finger of the same hand. The recorded data was searched sequentially manually to locate the first 30-pulse sequence in which the PPG amplitude of at least six PPG pulses was less than or equal to 60% of the maximum pulse amplitude in the sequence. The primary PPG parameter of interest was PAPPG. For the LDF signal, the pulse amplitude is designated as PALDF, the total LDF for each pulse is designated as LDFTOT, and the LDF pulsatile component is designated as PF. To investigate the relationship between LDF parameters and PAPPG a linear regression analysis of each 30-pulse sequence was done with PAPPG as the independent variable and each of the three LDF parameters individually (PALDF, LDFTOT, and PF) as dependent variables.  Results There was a statistically significant direct relationship between PAPPG and all three measures of blood perfusion (p<0.05). Correlation coefficients (R) varied among subjects but within-subject variations versus PAPPG were similar, having mean values that ranged from 0.665 to 0.694. The results also provided evidence in support of a direct relationship between the LDF pulsatility index, defined as the ratio of PF to its mean value., and PAPPG (R=0.779). Conclusions When finger PPG pulse amplitudes are measured in individual subjects there is a moderate-to-strong correlation between the PPG pulse amplitude changes and skin blood perfusion changes. This fact impacts the confidence in using the widely available PPG parameter, peripheral perfusion index, as an indicator of changes in tissue perfusion. However, differences in the PPG pulse amplitude among subjects were less reliable indicators of differences in blood perfusion among subjects. The findings also indicate that a related parameter, the LDF pulsatility index, is also highly correlated with the PPG pulse amplitude and may serve as a useful parameter for future clinical investigations.

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.

The effect of different bed head angles on the hemodynamic parameters of intensive care patients lying in the supine position: A quasi-experimental study

AIMS

The aim of this study was to research the effect of different bed head angles on the hemodynamic parameters of intensive care patients lying in the supine position.

METHODS

This study was a non-randomized and non-controlled, quasi-experimental repeated measures study. The study was conducted with 50 intensive care patients aged 18 and over in a general surgery intensive care unit in Turkey. With each patient in the supine position, the bed head was raised to an angle of 0°, 20°, 30°, and 45° without a pillow, and the hemodynamic parameters of central venous pressure, systolic and diastolic blood pressure, heart rate, breathing rate, and peripheral oxygen saturation were recorded after 0 and 10 min.

RESULTS

It was found that the mean central venous pressure value measured at min 0 and 10 was higher when the intensive care patients' bed head angle was raised to 45° than when the bed head was at an angle of 0° or 20° (p < .05). It was found that the patients' other hemodynamic parameters were not affected by different bed head angles.

CONCLUSIONS

It was concluded as a result of this research that in intensive care patients in the supine position, only central venous pressure was affected by bed head angle, and that central venous pressure measurement can be reliably made at a bed head angle of 30°.

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).