Reproducibility of the Pleth Variability Index in premature infants

Goal-directed fluid therapy guided by plethysmographic variability index versus conventional liberal fluid therapy in neonates undergoing abdominal surgery: A prospective randomized controlled trial

BACKGROUND

Intraoperative fluid therapy maintains normovolemia, normal tissue perfusion, normal metabolic function, normal electrolytes, and acid-base status. Plethysmographic variability index has been shown to predict fluid responsiveness but its role in guiding intraoperative fluid therapy is still elusive.

AIMS

The aim of the present study was to compare intraoperative goal-directed fluid therapy based on plethysmographic variability index with liberal fluid therapy in term neonates undergoing abdominal surgeries.

METHODS

A prospective randomized controlled study was conducted in a tertiary care centre, over a period of 18 months. A total of 30 neonates completed the study out of 132 neonates screened. Neonates with tracheoesophageal fistula, congenital diaphragmatic hernia, congenital heart disease, respiratory disorders, creatinine clearance <90 mL/min and who were hemodynamically unstable were excluded. Neonates were randomized to goal-directed fluid therapy group where the plethysmographic variability index was targeted at <18 or liberal fluid therapy group. Primary outcome was comparison of total amount of fluid infused intraoperatively in both the groups. Secondary outcomes included intraoperative and postoperative arterial blood gas parameters, biochemical parameters, use of vasopressors, number of fluid boluses, complications and duration of hospital stay.

RESULTS

There was no significant difference in total intraoperative fluid infused [90 (84-117.5 mL) in goal-directed fluid therapy and 105 (85.5-144.5 mL) in liberal fluid therapy group (p = .406)], median difference (95% CI) -15 (-49.1 to 19.1). There was a decrease in serum lactate levels in both groups from preoperative to postoperative 24 h. The amount of fluid infused before dopamine administration was significantly higher in liberal fluid therapy group (58 [50.25-65 mL]) compared to goal-directed fluid therapy group (36 [22-44 mL], p = .008), median difference (95% CI) -22 (-46 to 2). In postoperative period, the total amount of fluid intake over 24 h was comparable in two groups (222 [204-253 mL] in goal-directed fluid therapy group and 224 [179.5-289.5 mL] in liberal fluid therapy group, p = .917) median difference (95% CI) cutoff -2 (-65.3 to 61.2).

CONCLUSION

Intraoperative plethysmographic variability index-guided goal-directed fluid therapy was comparable to liberal fluid therapy in terms of total volume of fluid infused in neonates during perioperative period. More randomized controlled trials with higher sample size are required.

TRIAL REGISTRATION

Central Trial Registry of India (CTRI/2020/02/023561).

Plethysmography variability index (PVI) changes in preterm neonates with shock-an observational study

Shock is an acute state of circulatory dysfunction. The diagnosis of shock is complex in neonates. The relative sensitivity of current clinical or laboratory findings for detecting shock is largely unknown, especially for preterm neonates. For preload assessment, inferior vena cava (IVC) collapsibility can be a useful bedside echocardiography parameter. plethysmography variability index (PVI) is a marker of fluid responsive shock in adults and children, but not well defined in neonates. In this prospective observational study, we evaluated the changes in PVI in preterm neonates with shock. Among the 37 infants enrolled in the study, the mean blood pressure (MAP) was 45 (± 4 mm of Hg) and none of infants had hypotension. The mean pulse pressure was 28 mm of Hg, the mean PVI was 28% (±5), the mean arterial blood gas pH was 7.20 (±0.07), and the mean base deficit was 9.9 (±2.53) at the onset of shock. Thirty (96.77%) of the 31 infants with resolution of shock showed decrease in PVI with an average decrease of 11% (±5).Conclusion: Significant proportion of neonates show an increase in PVI at the onset of shock. What is Known: • Plethysmography Variability Index (PVI) is commonly used as a marker of volume status in paediatric population. • Changes in PVI may guide in giving volume boluses in patients with shock. What is New: • This study provides information of changes in PVI in preterm neonates with shock. • PVI may become a valuable tool to be used at bedside in preterm infants with shock.

Comparison of pulse pressure variation and pleth variability index in the prone position in pediatric patients under 2 years old

Background

The assessment of intravascular volume status is very important especially in children during anesthesia. Pulse pressure variation (PPV) and pleth variability index (PVI) are well known parameters for assessing intravascular volume status and fluid responsiveness. We compared PPV and PVI for children aged less than two years who underwent surgery in the prone position.

Methods

A total of 27 children were enrolled. We measured PPV and PVI at the same limb during surgery before and after changing the patients’ position from supine to prone. We then compared PPV and PVI at each period using Bland-Altman plot for bias between the two parameters and for any correlation. We also examined the difference between before and after the position change for each parameter, along with peak inspiratory pressure, heart rate and mean blood pressure.

Results

The bias between PPV and PVI was −2.2% with a 95% limits of agreement of −18.8% to 14.5%, not showing significant correlation at any period. Both PPV and PVI showed no significant difference before and after the position change.

Conclusions

No significant correlation between PVI and PPV was observed in children undergoing surgery in the prone position. Further studies relating PVI, PPV, and fluid responsiveness via adequate cardiac output estimation in children aged less than 2 years are required.