Original Article. Nikita Panigrahi, Maaz Ahmad, Manas Ranjan Mishra, Basavaraja G V ****

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1 Original Article DOI with arterial carbon dioxide in mechanically ventilated children Nikita Panigrahi*, Maaz Ahmad**, Manas Ranjan Mishra***, Basavaraja G V **** *Senior Resident, Department of Pediatrics, ANIIMS, Port Blair,***Graded Specialist, Department of Pediatrics, INHS Dhanvantari, Port Blair,Andaman Nicobar Isls, India, **Assistant Professor, Department of Pediatrics**** Associate Professor of Pediatrics Incharge of PICU, Indira Ghi Institute of Child Heath, Bangalore, Karnataka, India Received: 26-Jul-18Accepted: 12-Aug-18Published online: 30-Aug-18 ABSTRACT Back ground:end-tidal carbon dioxide ( ) is a surrogate, non-invasive measurement of arterial carbon dioxide ( ); however, its clinical applicability in the intensive care unit setting remains unclear in pediatric population Objectives:This study aims at assessing the effect of severity of lung disease correlation between Materials methods: This was a prospective, nonromised study carried in pediatric intensive care unit of a tertiary care unit on 104 children requiring mechanical ventilation Simultaneous recording were taken, data on ventilator parameters recorded Severity of lung disease was estimated by alveolar- arteriolar oxygen gradient, ventilation index PaO2 ratio The difference its variability were studied Results:208 samples were analysed where the mean value 289±97 mmhg was higher than mean value of 278±96 mmhg The mean difference between PACO 2 was 16±323 mmhg There was significant level of correlation between PACO 2 ( r=0941, r 2 = 0886, 95% CI= ) for mild to moderate lung disease than severe lung disease Systemic diseases, Ventilator index alveolar arterial oxygen gradient did not have any significant correlation with the PACO 2 difference in our study Conclusion: Significant correlation was found between the value irrespective of the disease condition can be validated to predict PACO 2 Keyword : End-tidal carbon dioxide ( ), Arterial carbon dioxide ( ), Capnography, ventilated children Introduction Capnography is a useful monitoring tool during mechanical ventilation is the stard of care for confirmation of endotracheal tube placement, the integrity of the ventilator circuit for early detection of mishaps such as inadvertent extubation for monitoring in the operating room setting, but there is scarcity of data regarding utility of continuous capnography as a non-invasive mode of respiratory mechanics monitoring assessing the adequacy of ventilation in pediatric intensive care units 1,2 The accepted stard for measuring CO 2 production is still arterial blood analysis The appeal of this technique is blunted clinically as it is invasive, painful risk of infection bleeding from puncture site is more in critically ill patients transcutaneous Correspondence: Dr Basavaraja G V, Associate Professor of pediatrics&incharge of PICU,Indira Ghi Institute of Child Heath,Bangalore,India,- Phone: , basavgv@gmailcom monitoring is not well tolerated in infants requires frequent calibration Time-based capnography is best known as endtidal carbon dioxide (P ) monitoring When used without qualification, the term capnography refers to time-based values It provides qualitative information on the waveforms associated with mechanical ventilation a quantitative estimation of the partial pressure of expired CO 2 3,4,5 Variable correlation has been reported between ETCO2 in previously done studies in critically ill adults children However, many of these clinical situations involve patients with significant elevations in physiologic dead space Hence, the objective to study the correlation between the two entities, variability with respect systemic illness particularly severity of lung pathology determine if capnography can be used as a stard of care for non-invasive continuous monitoring in pediatric critical care unit Vol 5 - No4 Jul-Aug

2 Materials Methods This was a prospective study conducted in pediatric intensive care unit of a tertiary care hospital from January 2015 to January 2016 All children aged one month to 16 years requiring mechanical ventilation were enrolled in this study Baseline clinical demographic details were collected entered in prestructured pre designed proforma Indication for ventilation diagnostic details noted For every arterial blood gas obtained as per PICU protocol values were recorded ETCO2 was measured with Philips Capnostat M2501A attached to the Philips MP30 MP70 IntelliVue monitors, calibrated with each device check Simultaneous ABG measurements were recorded on a bedside data sheet On an average, two pairs per patient were drawn a minimum interval of 12 hours was maintained between two successive measurements on same patient Children with poor cardiac output, suspected intracardiac shunting were excluded A total of 208 samples were collected from 104 children Prior to data collection suctioning was done, endotracheal tube position was checked ensured minimal leak of the ventilator circuit At the same time ventilator parameters were collected on modes of ventilation, FiO 2 (Fractional Inspired oxygen concentration), inspiratory expiratory tidal volumes, peak inspiratory pressure (PIP), positive end expiratory pressure (PEEP), respiratory rate (RR), oxygen saturation Calculated data as measures of severity of lung disease included were PF Alveolar arteriolar oxygen gradient The alveolar gas equation was used to calculate the alveolar oxygen tension (PAO 2 ) The alveolar- arterial oxygen tension difference P(A-a)O 2 was estimated by subtracting the concurrent measured from the measured PAO 2 in mmhg It is indicative of intrapulmonary shunt 6 PAO 2 = ( FiO 2 x P atm - P H2o ) - ( R) Patm - atmospheric pressure in mmhg; PH 2 O- partial pressure of water- 47 mm hg, R- respiratory coefficient- 08 Baseline characteristics were described using frequencies proportions for categorical variables A linear regression analysis was done to find the equation between Bl Altman Plot was created to evaluate agreement Data were analyzed using the SPSS statistical software version 22 No direct intervention was done on the patients This study was approved by the institutional ethical committee review board Results In this study 208 concurrent samples from 104 patients were taken from children who were mechanically ventilated The demographic data of the study population is shown in table 1 Minimum age of the child in the study group was 3 months maximum16 years There was no correlation found between the age, sex or weight with the The mean value was 289 (SD±97) mmhg 278 (SD± 96)mmHg The mean difference between is 16 (SD± 323) mmhg The value is higher than in 729% cases lower than in 2307% The subcategories where less than 1 were respiratory disorder in 354 %, CNS disorders in 312%, septic shock in 125%, CVS in 104 % cases The difference was not significantly affected by disorder leading to mechanical ventilation Table 1: PF ratio its correlation to P (a- ET) CO 2 difference Frequency (n) Percentage (%) P (a-et) CO 2 Median SD (min, max) FiO 2 < (-8,8) FiO 2 > (- 10,11) Correlation coefficient (spearman Rho) P- value Over all excellent correlation was found between concurrent PaCO2 ETCO2 values r=0941, R 2 = % CI = ( ) This scatter diagram (Fig1) shows the regression analysis between the two variables Here the Y - axis represents the value Vol 5 - No4 Jul-Aug

3 whereas the X-axis represents the there is a significant R 2 =0884 The value can be derived from using the following equation Y= *x Y= P X= The Bl Altman Plot (Fig 2) suggests that the two variables EtCO 2 have significant correlation with narrow confidence interval ( ) disease (PaO2FiO2 >200) had significant correlation (p<0001) with (spearman Rho correlation coefficient of 0932) Th e ETCO2 difference of 2±323 mmhg, with low level of positive correlation between PF ratio with the difference ( r = 0186) For severe lung disease was considered ( FiO2 <200) has significant correlation(p<0001) ( spearman Rho correlation coefficient of 0861) The difference of 23 ± 324 mmhg with negative correlation coefficient (r=-0449) It suggests that as the ratio increases,the difference between the two variables is less the predictive capability of is more Table 2: correlation according to categorical variation in ratio P value Spearman Rho correlation Coefficient < <0001 > <0001 Figure 1: Scatter diagram showing the correlation between the regression analysis, X- axis- Y axis- Figure 2: Bl Altmann plot for PACO 2 Severity of lung disease was considered according to Pa O 2 (Table1,2) For mild to moderate lung The alveolar arteriolar oxygen gradient reflects the ventilation perfusion mismatch in the lung parenchyma There was no significant (p-0462) correlation between the (A-a) O 2 gradient the P (a-et) CO 2 difference Discussion Capnography can be a useful early indicator of changes in a patient s cardiopulmonary status due to alterations in pulmonary blood flow, respiratory effort, effective minute ventilation, or respiratory compliance 7 However, there is significant debate as to whether capnography is useful as a continuous monitoring technique for mechanically ventilated patients In present study the mean P(a-ET)CO2 difference was 16 ± 323 mmhg with the maximum difference of 11 mmhg maximum negative difference ( ie, was more than ) of -8 mmhg Yamanaka et al, reported that an admixture of this blood into the arterial circulation contributes to increased gradients 8 This increase Vol 5 - No4 Jul-Aug

4 may be up to 20 mmhg in patients with severe pulmonary or major systemic disease Similar results were found in a study done by Mc Donald et al the (399 ± 127 mmhg) was lower than the (455 ± 141 mmhg) 9 In a study done by Goonasekara, 10 average reading of was consistently +066 KPa (95% confidence interval: +057 to +076) higher than that of P shows an excellent correlation with (r = 0941, R 2 =0886, CI ) Similar results were found in a study done by Hiren mehta et al between the two variables in infants children with r = 0914, a narrow CI = , R2 = In mild to moderate lung disease ( FiO2 >200) in our study correlation coefficient between was r= 0932 where as in severe lung disease r = 0831 Similarly in study done by Hiren Mehta et al, there was a strong correlation in patients with PF >200, r = 094, (95% CI = ) R 2 = In severe lung disease when PF ratio was <200, the correlation was good r = 0782, R 2 = 068 The above difference can be explained as measurements are affected by alveolar CO 2 levels, dead space fraction pulmonary perfusion Nonuniform alveoli CO 2 emptying patterns in patients with large ventilation perfusion result in mismatching PACO 2, underestimation of levels 12 A high ventilationperfusion ratio dead space tends to cause low levels relative to, whereas a low ventilation perfusion ratio shunt has little effect on causing a smaller measure relative to Previous studies reported an influence of alveolar arteriolar oxygen gradient, ratio ventilator index on correlation of, but we found only ratio to be useful in assessing the effect of severity of lung disease on this relationship 12 The limitations could be more continuous monitoring per patient is required to establish the influence of VI (A-a) O 2 gradient on the relationship Oxygenation index, coexisting conditions like shock, hypotension, raised intracranial pressure should be considered Larger sample sizes with more continuous monitoring of with analysing capnogram waveform volumetric capnography will have better predictability in lung pathology more accurate monitoring of ventilator patients can be used as a non-invasive mode of monitoring in case of mechanically ventilated children, thus reducing the frequency of arterial blood gas sampling Endotracheal tube blockage displacement can be diagnosed earlier patients can be weaned off ventilator faster by continuous monitoring of Conclusion Significant correlation was found between the value irrespective of the disease condition can be validated to predict PACO 2 Conflict of Interest : Nil Source of Funding : Nil References 1 Neumar RW, Otto CW, Link MS, Kronick SL, Shuster M, Callaway CW,et alpart 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation Emergency Cardiovascular Care Circulation 2010;122:S Walsh BK, Crotwell DN, Restrepo RD Capnography Capnometry during mechanical ventilation: 2011 Respir Care 2011;56: Chopin C, Fesard P, Mangalaboyi J, Lestavel P, Chambrin MC, FourrierF,et al Use of capnography in diagnosis of pulmonary embolism during acute respiratory failure of chronic obstructive pulmonary disease Crit Care Med 1990;18: Verschuren F, Liistro G, Coffeng R, Thys F, Roeseler J, Zech F, et al Volumetric capnography as a screening test for pulmonary embolism in the emergency department Chest 2004;125: Tusman G, Areta M, Climente C, Plit R, Suarez-Sipmann F, Rodriguez-Nieto MJ,et al Effect of pulmonary perfusion on the slopes of single-breath test of CO2 J Appl Physiol 2005;99: Brain R Wood Physiologic principles In: Jay P Goldsmith, Edward Karokin editors Assisted ventilation of the neonate, 4th ed, Elsiever; 2009 p Blanch L, Lucangelo U, Lopez-Aguilar J, Fernez R, Romero PV Volumetric capnography in patients with acute lung injury: effects of positive end-expiratory pressure Eur Respir J 1999;13: Yamanaka MK, Sue DY Comparison of arterial-end-tidal PaCO2 difference dead spacetidal volume ratio in Vol 5 - No4 Jul-Aug

5 respiratory failure Chest 1987;92(5): McDonald MJ, Montgomery VL, Cerrito PB, Parrish CJ, Bol KA,Sullivan JE Comparison of end-tidal CO2 PaCO2 in children receiving mechanical ventilation Pediatr Crit Care Med 2002;3: Goonasekera CD, Goodwin A,Wang Y, Goodman J Arterial end tidal carbon dioxide difference in pediatric intensive careindian J Crit Care Med 2014; 18(11): Mehta H,KasypR, Trivedi S Correlation of End-Tidal arterial carbondiaoixe in crtically ill neonates children Indian J Crit Care Med 2014;18:348-53d 12 Bhavani-Shankar K, Moseley H, Kumar AY, Delph Y Capnometry anaesthesia Can J Anaesth 1992;39: Takki S, Aromaa U, Kauste A The validity usefulness of the endtidalpco 2 during anaesthesia Ann Clin Res 1972;4: How to cite this article: Panigrahi N, Ahmad M, Mishra M, Basavaraja GV with arterial carbon dioxide in mechanically ventilated children J Pediatr Crit Care 2018;5(4):15-19 How to cite this URL: Panigrahi N, Ahmad M, Mishra MR, Basavaraja GV with arterial carbon dioxide in mechanically ventilated children J Pediatr Crit Care 2018;5(4):15-19 Available from: Vol 5 - No4 Jul-Aug

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