Dr. Subash ArunGuide

Dr Srinivas Murki

Plethysmography variability index(PVI)changes in neonates with shock

and its correlation to IVC collapsibility index (IVCI)– An Observational Study

Hyderabad, INDIAwww.fernandezhospital.com

Introduction

▪ Diagnosis and Management of shock is challenging

▪ Routine clinical parameters - very low diagnostic utility

▪ Bedside ECHO : Routine practice for managing shock in NICU

▪ Pleth variability index (PVI)

– A marker of fluid responsive shock

– Has not been utilized in neonates with shock yet

Existing Evidence

▪ Only few studies evaluated the role of fECHO in neonatal Shock (Bagci et al)

▪ These studies evaluated Hemodynamics at onset of shock

▪ Comparison with control is missing

▪ Enrolled newborns with only septic shock

Study Objective

To evaluate the changes in

▪ Pleth variability index (PVI)

▪ Blood pressure (systole, diastole, mean

arterial pressure i.e. MAP) and

▪ Echocardiographic marker IVC CI

Onset of Shock Complete Resolution of shock

Patients

▪ All neonates with shock included in study

Exclusions

▪ Received fluid boluses or inotropes prior to enrollment

▪ Neonates having major congenital anomalies

▪ Neonates undergoing therapeutic hypothermia

Methods▪ Prospective observational study

▪ October 2017 to May 2019

▪ Fernandez Hospital, Hyderabad – Tertiary care hospital

▪ Consent : At admission to NICU for possible enrollment

▪ All newborns were screened for features of shock hourly

▪ Newborns diagnosed with shock were monitored for

Clinical parameters

PVI

IVC CI

Shock defined as

Any 2 of following 6 parameters*

▪ HR>180/min

▪ CRT>3 sec

▪ Core to periphery difference >30C

▪ Base Excess >-5 in blood gas/ Lactate > 2 times normal

▪ Hypotension:

▪ Oliguria* International paediatric sepsis consensus conference, Goldstein B et al

Echocardiographic Evaluation

Echo imaging was done only by PI who was trained by pediatric cardiologist

▪ IVC collapsibility index Preload

Shock ResolutionAll of the following should be present

▪ Heart rate 120 to 160 per min

▪ Capillary refill time < 3 seconds

▪ Blood pressure : >30 mm of Hg/ >5th GA

> 5th Centile for GA or systolic BP >2SD

▪ Urine output : >1 ml/kg/hour

▪ Normal peripheries Core to peripheral temperature < 3°C

▪ Not on inotropes

▪ No acidosis and normal lactate

Primary Outcome

▪ Median Change in

– Clinical Parameters

– PVI

– IVC CI

At Onset of shock and at complete resolution of shock

Secondary Outcome

▪ Comparison of Clinical diagnosis versus echo diagnosis of Shock

Protocol

▪ For logistic and ethical reasons, only feasible parameters were recorded before giving bolus and rest either before or during saline bolus infusion / starting of inotropes

▪ Echo images - reviewed by pediatric cardiologist blinded to clinical findings

▪ Shock Management - as per standard unit protocol

▪ Clinical and echo parameters -repeated after resolution

Sample Size and Statistics

▪ No a-priori sample estimation done

▪ Median changes in clinical, PVI and IVC CI parameters at onset and at the resolution of shock done by paired ‘t’ test

▪ All the analysis was done using statistical software packages SPSS version 23 (IBM, New York)

Results

Infants admitted to NICU (N=1416)

Infants Diagnosed with shock

(N= 59)

Infants enrolled for study (N= 37)

Infants for paired analysis (N=31)

Excluded cases before

enrollement(N=22)

Excluded cases after enrollment

from paired analysis (N=6)

Study flow chart

Indicator of shock Number(percent)N=37

HR>180/min 35(94.5)

CRT>3 sec 26(70)

Core to periphery difference >30C 30(81)

Base Excess >-5 in blood gas 33(89.18)

Elevated Lactate > 2 times 35(94.5)

Hypotension 0(00)

Oliguria 0(00)

Diagnosis of Shock

Characteristics/ Variables Baseline data

Gestational Age (weeks) 30±3

Maternal age (years) 28.5±3.8

Birth weight (grams) 1213±448

Male gender (%) 20 (54)

Small for date (%) 9 (24.3)

Age at shock (days) 3.5 (2.5,6)

Weight loss at shock (%) 7.9±4

Blood pH at shock 7.20 (± 0.07)

Base Excess at shock 9.87 (± 2.5)

Blood culture +ve sepsis (%) 21 (56.8)

Probable sepsis (%) 6 (16.2)

HsPDA (%) 6 (16.2)

Baseline Characteristics

Characterstics/ Variables Baseline data

SBP(mmhg) 62(±9)

DBP(mmhg) 34(±6)

MAP(mmhg) 45(±6)

Pulse Pressure 28(±6)

PVI(%) 28(±5)(25,33)

IVC collapsibility index(%) 38(±5)

Baseline Characteristics

Parameter Mean difference(SD)

CI

HR(min) 45±15,p<0.001 CI 95%(39-50)

MAP (mm of hg) 2.8±5.1,p<0.004 Cl 95%(0.9-4)

PVI(%) 12±5,p<0.001 Cl 95%(9-13)

IVC collapsiability index 12±13 p<0.001 Cl 95%(6-16)

Infants at shock and after resolution of shock

In present study median PVI at time of shock was28% (25, 33) and median PVI after completeresolution of shock was 16% (14, 18)

Twenty four (77.4%) infants had decreased IVCcollapsibility index and the average change was 12%(±13)

Box plot showing changes in PVI and IVC CI after paired analysis

Variables PVI(r)

IVC collapsiability index 0.365(p=0.034)

HR 0.285(p=0.088)

MAP -0.093(p=0.585)

Pulse Pressure 0.006(p=0.973)

Pearson Correlation

▪ PVI a measure of volume status, correlatedpositively with IVC collapsibility index

▪ Increased PVI is directly related to increased IVCcollapsibility index, (Pearson correlationcoefficient [r =0.36, p=0.03])

▪ PVI did not show significant correlation withother clinical parameters like HR, MAP and pulsepressure

Parameters Medians (IQR) P value

At shock After resolution

PVI (%) 28(25,33) 16(14,18) <0.001

IVC Collapsibility Index % 42(23,48) 25(18,33) <0.001

Changes in Preload Parameters at Onset and Resolution of Shock

Study Strengths

▪ First study to evaluate PVI and IVC CI Parameters at onset and after shock resolution

▪ Ideal study in which each infant acted as its own control

▪ Identified the median differences in Clinical, PVI and IVC CI parameters in newborns with shock

▪ Includes newborns with all types of shock (not only sepsis)

▪ Cardiologist blinded to the clinical details

Median Changes (Onset vs. Resolution)

▪ Preload PVI 12%

IVC CI 13%

Clinical Application of Study Findings

Clinical Implications

▪ Identify infants at risk for shock at admission to

NICU

▪ Evaluate PVI, IVC collapsibility index, MAP at

admission or as early as possible

▪ Revaluate the same parameters at onset of shock

to Classify pathophysiology of shock

▪ Manage shock from pathophysiology

Study Limitations

▪ Exclusively inborn neonates

▪ Sample size small

Conclusion

Our study highlights the correlation of PVI and IVC CI at onset and resolution of shock which helps in early aggressive clinical management in neonates at high risk of shock