Predictive value of perfusion index for diagnosis of shock in neonates

Prsent study is designed to evalaute utility of perfusion index for diagnosis of shock in neonates. In present study allneonates will be enrolled at time of admission to NICU. Demographiccharacteristics and antenatal details of enrolled infants, including maternalhypertension, fetal growth restriction, umbilical artery Doppler abnormality,chorioamnitis, antenatal steroid cover, and mode of delivery will be recordedon a proforma. Neonates  will be cared inthermoneutral environment, under radiant warmer/incubator, with care to preventcold stress.

Data recording:

Neonates will be continuouslymonitored for clinical signs of perfusion including heart rate, BP, pulsevolume, CRT, central and peripheral temperature and urine output by attendingneonatal nurse.

HR and SPO2 and PIwill be recorded from Masimo pulse oximetry monitor, when neonate is in quietstate. Pulse volume will be assessed by palpating radial pulse by attendingneonatologist and will be categorized as good or poor pulse volume. PI will berecorded from Masimo pulse oximeters, Radical-7 display, with monitorconfigured for long format so as to get an average of last 5 min.

BP will be measuredin right arm, by oscillometric method using dreager vista monitor, with neonateis lying supine. An appropriate sized cuff (encircling 2/3rdof the circumference of limb) will be applied, preferably to the right upperarm. The infant will then left undisturbed for atleast 5 minutes, until he is quiet or asleep. Three successive BP recordingswill be taken at 2-minute intervals and average of these will be taken.

CRT will bemeasured using electronic stop watch. An area over sternum will be pressed withindex finger for 2 seconds and then released; time taken from release torefilling will be recorded.

Central andperipheral temperature will be recorded from electronic display ofwarmer/incubator with central probe applied over abdomen and peripheral probeapplied to sole of foot.

Urine output (per kgper hour) will be calculated from diaper weight, by dividing output inpreceding 2 diapers with the interval between these diaper changes.

Blood gas analysis(through arterial puncture or an indwelling arterial catheter) will be done ifa possibility of shock is considered, or for assessment of gas exchange incardio-respiratory disorders, or at per clinician’s discretion. Blood lactatevalues will be noted from concurrent blood gas analysis.

Toevaluate predictive value of each hemodynamic parameter, ROC curves will bedrawn and comparison of area under curve for each parameter will be done.Sensitivity, specificity, positive predictive value and negative predictivevalue and 95% confidence intervals for each parameters will be reported.

Definitionof shock

Abnormal findings willbe confirmed by attending neonatologist. Diagnosis of shock will be made ifthree or more of following are present:

·        Resting HR >180/min

·        Mean BP less than 10thcentile for gestational age

·        CRT > 3 sec

·        Central peripheral temperaturedifference > 4 *C

·        Poor peripheral pulses

·        Urine output <1 ml/kg/hr (preceding 6hrs)

·        Blood lactate >4 mmol/L