Pleth Variability Index to Assess Course of Illness in Children with Asthma

Pulse oximetry respiratory monitoring for assessment of acute childhood wheeze

OBJECTIVE

There is a lack of objective measures to assess children with acute wheezing episodes. Increased respiratory rate (RR) and pulsus paradoxus (PP) are recognised markers, but poorly recorded in practice. We examined whether they can be reliably assessed from a pulse oximeter plethysmogram ('pleth') trace and predict clinical outcome.

PATIENTS AND METHODS

We studied 44 children aged 1-7 years attending hospital with acute wheeze, following initial 'burst' bronchodilator therapy (BT), and used custom software to measure RR and assess PP from oximeter pleth traces. Traces were examined for quality, and the accuracy of the RR measurement was validated against simultaneous respiratory inductive plethysmography (RIP). RR and PP at 1 hour after BT were compared with clinical outcomes.

RESULTS

RR from pleth and RIP showed excellent agreement, with a mean difference (RIP minus pleth) of -0.5 breaths per minute (limits of agreement -3.4 to +2.3). 52% of 1 min epochs contained 10 s or more of pleth artefact. At 1 hour after BT, children who subsequently required intravenous bronchodilators had significantly higher RR (median (IQR) 63 (62-66) vs 43 (37-51) breaths per minute) than those who did not, but their heart rate and oxygen saturation were similar. Children with RR ≥55 per minute spent longer in hospital: median (IQR) 30 (22-45) vs 10 (7-21) hours. All children who subsequently required hospital admission had PP-analogous pleth waveforms 1 hour after BT.

CONCLUSION

RR can be reliably measured and PP detected from the pulse oximeter pleth trace in children with acute wheeze and both markers predict clinical outcome.

TRIAL REGISTRATION NUMBER

UKCRN15742.

Use of the pleth variability index in children with obstructive respiratory disease

INTRODUCTION

The phenomenon of pulsus paradoxus (PP) develops at varying rates in relation to the severity of the disease in obstructive respiratory tract disease. The Pleth Variability Index (PVI) is the measurement value of perfusion index changes that occur with ventilation, which are determined during at least one respiratory cycle. Therefore, noninvasive measurement of PVI can help in the measurement of PP. The current study aims to determine the role of PVI measurements before and after bronchodilator therapy during admission to the hospital in children with obstructive respiratory tract disease.

METHODS

Age, gender, Pulmonary Index Score (PIS), and PVI data of patients aged 2-18 years who applied to the pediatric emergency department with signs of obstructive respiratory tract disease were recorded in triage. The PVI and PIS scores of the patients, who were divided into three groups according to their clinical severity scores, were recorded before and after bronchodilator treatment, and they were compared to the PVI values according to the disposition results.

RESULTS

A total of 133 patients were included in this prospective, single-center study. The PVI values before and after treatment were significantly higher in patients with severe disease compared to the mild and moderate groups (p < 0.001). Post-treatment PVI values were significantly lower than pre-treatment values in all clinical severity groups (p < 0.001). While a total of 95 (71.43%) patients were discharged from the emergency department, 31 (23.31%) patients were admitted to the relevant department, and seven (5.26%) patients were admitted to the pediatric intensive care unit. The PVI values before and after treatment were significantly higher in the hospitalized group compared to the group discharged from the emergency department (p < 0.001). The areas under the ROCs were 0.940, 0.865, and 0.843 for the PVI measurements in patients with severe disease, moderate disease, and hospitalization (p< 0.001).

CONCLUSIONS

Automated PVI measurement can be used as a noninvasive, rapid, and objective tool in the emergency department triage of patients admitted to the pediatric emergency department with signs of asthma attack or reactive respiratory tract disease.

Assessment of pleth variability index in volume changes during ultrafiltration process

OBJECTIVES:

Pleth variability index (PVI) has been studied mostly in mechanically ventilated patients, and the role of PVI in predicting volume status and volume changes among spontaneously breathing patients is not clear in the literature. We hypothesized that hemodialysis (HD) can be a valid model for a simulation that can be evaluated the correlation of PVI with fluid changes in various volume states. The aim of this study was to investigate the utility of PVI for assessing volume changes in HD patients who are breathing spontaneously.

METHODS:

This prospective, observational study included patients aged 18 years or older who had end-stage renal failure and presented for routine HD between December 2019 and January 2020. PVI values were measured before and after HD session. Changes in PVI levels were compared according to the amount of ultrafiltration.

RESULTS:

A total of sixty patients were included. Mean PVI level before HD (20.7% ± 5%) showed a statistically significant increase to 27.7% ± 6% after HD session (P < 0.001). According to the amount of fluid removed during HD, the changes in PVI were statistically significant (P = 0.015). There was a strong correlation between ΔPVI and ultrafiltrated volume (r = 0.744, P < 0.001).

CONCLUSION:

The fluid removed by HD caused increase in PVI, and the increase was strongly correlated with the amount of volume change. Bedside monitoring of PVI may provide the clinicians with useful information for monitoring the volume status in critically ill patients with spontaneous breathing.