Original scientific paper
EFFECT OF GENDER AND BODY MASS INDEX ON ELECTRICAL IMPEDANCE TOMOGRAPHY FINDINGS DURING SPONTANEOUS BREATHING IN SUPINE POSITION
ANDREJ ŠRIBAR
; Dubrava University Hospital, Department of Anesthesiology, Resuscitation and Intensive Care Medicine, Zagreb, University of Zagreb, School of Dental Medicine, Zagreb, Croatia
VLASTA MERC
; Dubrava University Hospital, Department of Anesthesiology, Resuscitation and Intensive Care Medicine, Zagreb, Croatia
ZORAN PERŠEC
; Dubrava University Hospital, Department of Urology, Zagreb, North University, Varaždin, Croatia
ZRINKA ŠAFARIĆ OREMUŠ
; Dubrava University Hospital, Department of Anesthesiology, Resuscitation and Intensive Care Medicine, Zagreb, Croatia
NATAŠA GOCIĆ PERIĆ
; Clinical Center of Voivodina, Urgent Center, Novi Sad, Serbia
JASMINKA PERŠEC
orcid.org/0000-0002-3777-8153
; Dubrava University Hospital, Department of Anesthesiology, Resuscitation and Intensive Care Medicine, Zagreb, University of Zagreb, School of Dental Medicine, Zagreb, Croatia
Abstract
Aim: To assess correlation of electrical impedance tomography (EIT) fi ndings in obese patients spontaneously breathing in supine position with body mass index (BMI) and body surface area and to compare measurements in obese patients (BMI ≥30 kg/m2) with those recorded in patients with BMI <30 kg/m2. Patients and Methods: Thirty-two patients scheduled for elective urologic procedure were included in this study. Arterial blood was sampled and EIT recording was made before induction of anesthesia. End tidal (ETI) and end expiratory (EELI) lung impedance were measured, as well as center of ventilation and global inhomogeneity index. Data were exported using the Dräger EIT data analysis tool v. 6.3 and further analyzed in Microsoft Excel. Correlation coeffi cient was calculated using the Pearson or Spearman test of correlation and continuous variables were tested for statistical signifi cance using Student’s t-test or Mann Whitney U test, depending on the normality of distribution. Statistical analysis and data visualization were performed using software packages jamovi and PAST. Results: A signifi cant negative correlation was found between BMI and both ETI and EELI in all patients (EELI-BMI ρ=-0.35, p=0.047; ETI-BMI ρ=-0.35, p=0.046), and the correlation coeffi cient was even more pronounced between ETI and BMI in the obese population (ρ=-0.83, p=0.050). There was also a signifi cant negative correlation between age and Horovitz quotient (r=-0.36, p=0.044). No signifi cant differences in EIT measured parameters and arterial blood gas analyses were found between obese and non-obese patients. Discussion: Although there was a signifi cant negative correlation between lung impedances and BMI, as well as markedly increased ventilated area in the averaged tomogram in the non-obese group, no difference was found between obese and non-obese patients (with BMI ≥30 kg/m2 as a differentiator according to the WHO). However, since the correlation coeffi cient was much more pronounced in the obese group, the asymmetry between the groups (26 vs. 6 patients) could explain this discrepancy. There was no signifi cant difference in Horovitz quotient between the groups either, which could be attributed to preserved hypoxic pulmonary vasoconstriction and preserved functional residual capacity in the awake state. These facts should be taken into consideration when interpreting the data, as the loss of functional residual capacity coupled with rapid desaturation of arterial blood after induction of general anesthesia has been well documented and measured. Conclusion: End-tidal and end-expiratory lung impedance loss correlates well with an increase of BMI in spontaneously breathing patients, but no signifi cant differences were found between obese and non-obese patients either in EIT fi ndings or on arterial blood gas analyses. Further studies are needed to assess EIT measured differences in obese patients after induction of anesthesia.
Keywords
obesity; respiration; electrical impedance tomography
Hrčak ID:
237916
URI
Publication date:
24.4.2020.
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