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