Comparison of High-Flow Nasal Cannula and Conventional Oxygen Therapy Following Extubation After Pediatric Cardiac Surgery: A Retrospective Study

Ömer Faruk Şavluk1, Abdullah Arif Yılmaz2, Yasemin Yavuz1, Fatma Ukil Işıldak1, Babürhan Özbek2, Ergin Arslanoğlu2, Nihat Çine2, Hakan Ceyran2

1Department of Anesthesiology and Reanimation, Kartal Koşuyolu High Specialization Training and Research Hospital, Istanbul, Turkey
2Department of Pediatric Cardiac Surgery, Kartal Koşuyolu High Specialization Training and Research Hospital, Istanbul, Turkey

Keywords: Conventional oxygen therapy; high-flow nasal cannula; pediatric cardiac surgery.

Abstract

Introduction: Infants and children with congenital heart disease may develop respiratory failure in association with cardiac surgery or as a result of heart disease. In fact, the postextubation period in this group of patients can be complex and the use of continuous positive airway pressure or non-invasive ventilation may be necessary if conventional oxygen therapy is not sufficient. The aim of our study was to compare efficiency and outcomes of high-flow nasal cannula or conventional oxygen therapy post-extubation after pediatric cardiac surgery.

Patients and Methods: A single centre retrospective study was conducted between January and December 2020 in our 12 beds pediatric cardiac intensive care unit. Patients were divided into two groups. In one group 45 patients (Group I), those who received high-flow nasal cannula after extubation, and in the other group 45 patients (Group II), those who received oxygen therapy with a mask after extubation. The aim of the study was to evaluate the rela- tive efficacy of high flow nasal cannula and conventional oxygen therapy on PaCO2, PaO2 and PaO2/FiO2.

Results: PaO2 values at 1, 6, 12, 24 and 48 hour post-extubation were significantly higher in high-flow nasal cannula group (p< 0.05). PaCO2 values were significantly lower in the high-flow nasal cannula group at 1, 6, 12, 24 and 48 hour post-extubation (p= 0.01). PaO2/FiO2 values in high-flow nasal cannula group at all-time points post-extubation were significantly higher than in conventional oxygen therapy group (p= 0.01).

Conclusion: High-flow nasal cannula is useful in decreasing PaCO2 and improving PaO2 in children follow- ing extubation after cardiac surgery. In addition, the simplicity of and tolerability to high-flow nasal cannula is also important. Although more expensive, the use of high-flow nasal cannula can be considered as a safe and effective alternative to conventional oxygen therapy following pediatric cardiac surgery.

Introduction

Infants and children with congenital heart disease (CHD) may develop respiratory failure in association with cardiac surgery or as a result of heart disease. After cardiac surgery requiring cardiopulmonary bypass (CPB), respiratory failure due to fluid accumulation, inceased pulmonary vascular resistance, muscular weakness, diaphragmatic fatigue and edema can be seen in patients(1). The most common causes of morbidity and mortality in cardiac surgeries are pulmonary complications with wide variation of incidence, from 6% to 76%(2). It is believed that factors such as general anesthesia, surgical incision, CPB, ischemia time, intensity of surgical manipulation and number of drains may predispose patients to pulmonary function changes, that are highly related to the onset of respiratory complications after cardiac surgery(3-5). Among the various postoperative complications of cardiac surgery in children, the most common are respiratory stridor secondary to glottal edema, atelectasis, pulmonary edema, pleural effusion, chylothorax, diaphragmatic dysfunction, and pneumonia associated with mechanical ventilation. These and other complications can lead to respiratory failure(6,7). In fact, the postextubation period in this group of patients can be complex and the use of continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) may be necessary if conventional oxygen therapy (COT) is not sufficient.

Oxygen therapy with HFNC is currently a popular modality of respiratory support in pediatric care. HFNC ventilation refers to the delivery of a mixture of air and oxygen through a humidified circuit with very high flows, which exceed the patient’s spontaneous inspiratory demand. HFNC delivers heated and humidified gases and provides some level of CPAP, yet the exact amount cannot be predicted(8,9).

The use of HFCN has been shown to reduce airway resistance and to flush nasopharyngeal dead space, thus contributing to reduction of respiratory work favouring the elimination of CO2 and bronchial secretions(10,11).

Despite the widespread use of HFNC in the pediatric intensive care unit, the physiological and clinical effect of HFNC therapy on pediatric patients with respiratory distress after cardiac surgery has not been thoroughly investigated(12,13).

The aim of our study was to evaluate CO2 elimination, improve O2 and effect on PaO2 /FiO2 ratios postextubation after pediatric cardiac surgery using HFNC or COT.

Materials and Methods

A single centre retrospective study was conducted between January and December 2020 in our 12 beds pediatric cardiac intensive care unit. The study was approved by local ethic committee (2021/3/470). In our study, it was divided into two groups. In one group there were 45 patients (Group I), those who received HFNC after extubation, and in the other group there were 45 patients (Group II), those who received oxygen therapy with a mask after extubation. The aim of the study was to evaluate the relative efficacy of HFNC and COT on PaCO2 , PaO2 and PaO2 /FiO2 .

Children younger than two years undergoing elective cardiac surgery under CPB with a Risk Adjustment for Congenital Heart Surgery (RACHS) score of 2 and more were included in the study. Children with major congenital malformations or neuromuscular diseases, on ventilator support before surgery and cyanotic children undergoing palliative surgeries were excluded from this study.

Demographic data (age, weight) and baseline data such as CPB time, cross-clamp time, duration of mechanical ventilation, including heart rate (HR), invasive blood pressure, respiratory rate (RR) were recorded. Arterial blood gases were checked and collected with the child receiving CPAP before extubation and 1, 6, 12, 24 and 48 hours after extubation.

Outcomes

The primary outcomes were the changes of respiratory and hemodynamic changes in both groups. Basal variables including PaO2 , PaCO2 and PaO2 /FiO2 were initially obtained. These variables were recorded at 1, 6, 12, 24 and 48 hours after extubation period. Secondary outcome was reintubation rate. The decision of reintubation was made by the clinician. Efficacy was determined by normal CO2 levels (35-40 mmHg) and higher PaO2 levels with better PaO2 /FiO2 values.

For HFNC therapy, the appropriate-sized nasal cannula was selected, and the gas mixture was set at 1-2 L/kg/min. For COT, cannulas delivering maximum flow rate of 5-6 L/min were used. COT was delivered by face mask with the same target SpO2 . In this group, oxygen was delivered with a flowmeter from wall oxygen and humidification with a closed sterile water system at room temperature. The FiO2 in the COT group was calculated using Finer’s formula for low-flow COT(14).

No complications related to HFNC such as nasal ulcers, gastric distension were seen in children who were applied HFNC.

Statistical Analysis

Continuous data were expressed as mean ± standard deviation and compared by an independent samples t-test or the Mann-Whitney U test as appropriate for comparison of continuous variables between the two groups. Chi-square test was used for categorical parameters. p< 0.05 was considered stastically significant.

Results

Ninety children were enrolled for the study (45 in Group I and 45 in Group II). Demographic data and baseline parameters (PaO2 , PaCO2 and PaO2 /FiO2 ) were comparable between Group I and II (Table 1). RACHS catagories were not significantly different between two groups (p= 0.12). The mean duration of mechanical ventilation was not significantly different between HFNC and COT groups (p= 0.84).

Table 1. Demographic characteristics and baseline parameters

Primary Outcomes

PaO2 values at 1, 6, 12, 24 and 48 hours post-extubation were significantly higher in HFNC group (p< 0.05) (Table 2). PaCO2 values were significantly lower in the HFNC group at 1, 6, 12, 24 and 48 hour post-extubation (p= 0.01) (Table 3). And PaO2 / FiO2 values in HFNC group at all-time points post-extubation were significantly higher than in COT group (p= 0.01) (Table 4).

Table 2. Arterial oxygen tension (PaO2 ) at different time points

Table 3. Arterial carbon dioxide tension (PaCO2 ) at different time points

Table 4. PaO2 /FiO2 ratio at different time points

Secondary Outcomes

After the extubation, 5 patients (11%) in the HFNC group and 6 patients (13%) were reintubated. There were also no statistically significant differences between two groups (p= 0.48). However, There were no significant differences in systolic, diastolic blood pressure and HR levels during the extubation period in both groups (Table 5). During the extubation period, RR at all time were significantly lower in the HFNC group compared to COT group (respectively, p= 0.003, p= 0.004, p= 0.004, p= 0.005 and p= 0.005) (Table 5).

Table 5. Hemodynamic and respiratory parameters after extubation period

Discussion

Oxygen delivery with nasal cannula and face mask is a traditional method used for hypoxemic respiratory failure after extubation period(15,16). However, the use of HFNC has recently gained increasing acceptance and popularity in the treatment of respiratory conditions(9,17). HFNC is currently being applied to patients of all groups, from preterm infants to adults(9,18). Despite the widespread use of HFNC in the pediatric intensive care unit, the physiological and clinical effect of HFNC therapy on the pediatric patients with respiratory distress after cardiac surgery has not been fully investigated(12).

The aim of our study was to compare the efficiency and outcome of oxygen therapy using HFNC and COT after extubation in pediatric cardiac surgery.

Considering the complex respiratory and cardiac pathophysiology in children with heart disease, several effects on the hemodynamics of patients should be noted after congenital heart surgery. Low cardiac output syndrome (LCOS) is offen seen after congenital heart surgery and contributes to significant postoperative morbidity and mortality(19). In the presence LCOS, increased work of breathing (WOB) is poorly tolerated; excessively negative intrathoracic pressure increases systemic ventricular afterload, while increased diaphragmatic oxygen consumption reduces oxygen delivery to vital organs(20). In this stuation, HFNC therapy helps to decrease afterload by providing positive pressure and via unloadi ng of respiratory and cardiovascular work(20,21). Another, an upper airway obstruction (UOA) is relatively common after pediatric cardiac surgery and has been implicated as an important contributor to extubation failure in this population(22). UOA increases negative swings of intrathoracic pressure and increases WOB, thereby imposing an undue burden on a recovering myocardium and further complicating LCOS; HFNC therapy could alleviate the WOB and large negative swings of intrathoracic pressure(13).

Our primary aim was to compare postoperative PaO2 and PaCO2 values in the post-extubation period. Roca et al. showed that significant improvement in respiratory parameters and arterial blood gases in adults as early as 30 min of HFNC in comperison with 30 min of COT with face mask(23). Another prospective, observational study in adults also compared HFNC with COT in patients with acute respiratory failure. This study concluded that the use of the HFNC significantly reduced respiratory rate and improved PaO2 values(24). In our study, we also found comfirmed beneficial effect of HFNC in improving PaO2 levels at all time post-extubation (p< 0.05). Additionally, the HFNC group had better CO2 elimination compared to the COT group, being statistically significant at all time (p< 0.05). PaO2 /FiO2 ratio was higher in HFNC group than COT group (p< 0.05). Frizzola et al. showed that a flow dependent improvement in gas Exchange as evidenced by the PaCO2 (25). Accordingly, we evaluated that the increased flow of HFNC was able to flush the nasopharyngeal space and improve CO2 elimination in the post-extubation period following pediatric cardiac surgery. We showed that HFNC therapy decreases PaCO2 post-extubation in children. Another study reported better values in SpO2 levels and no difference in PaO2 /FiO2 with HFNC therapy after extubation. The authors also showed decreased respiratory rates, and PaCO2 levels after extubation for the HFNC group as compared with noninvasive ventilation group(26). Similar to our study, we found, improved PaO2 , decreased CO2 levels and respiratory rates after extubation with HFNC therapy.

Parke et al. found that there was a consistent drop, between subjects, in breathing frequency on initiation of high-flow nasal therapy. The authors speculated that this decrease in breathing frequency might be primarily to a reduction in physiological dead space and the plateau effect seen is consistent with this because the expected benefits of nasopharyngeal washout may reach a ceiling at the flow that provides for no rebreathing of dead space gas(13,21). An alternative or additional explanation is that, this drop in respiratory rate may have been due to a mild degree of hypoxaemia.

Additionaly, in our study, 11 patients were reintubated after extubation. Five patients were in HFNC group and 6 patients were in COT group. In present study, there was no difference between the two groups regarding incidence of reintubation. Testa et al. reported that there were no significant differences in reintubation in both groups(12,16). However, in another study, comparing the effects of the venturi mask and HFNC therapy showed less required reintubation following extubation in the HFNC group(27). We observed no complications such as nasal ulser, gastric distension during HFNC therapy like study of Burra et al.(9). However, a nasogastric tube was left after extubation in all children.

In conclusion, HFNC is useful in decreasing PaCO2 and improving PaO2 in children following extubation after cardiac surgery. In addition, the simplicity of and tolerability to HFNC is also important. Although more expensive, the use of HFNC can be considered as a safe and effective alternative to conventional oxygen therapy following pediatric cardiac surgery.

Cite this article as: Şavluk ÖF, Yılmaz AA, Yavuz Y, Ukil Işıldak F, Özbek B, Arslanoğlu E, et al. Comparison of high-flow nasal cannula and conventional oxygen therapy following extubation after pediatric cardiac surgery: a retrospective study. Koşuyolu Heart J 2021;24(Suppl 1):S8-S12.

Ethics Committee Approval

This study was approved by Kartal Kosuyolu High Specialization Training and Research Hospital Ethics Committee (2021/3/470).

Peer Review

Externally peer-reviewed.

Author Contributions

Concept/Design - ÖŞ; Analysis/Interpretation - ÖŞ; Data Collection - YY, FI; Writing - ÖŞ, AY; Critical Revision - BÖ, EA, NÇ; Final Approval - ÖŞ, HC; Statistical Analysis - ÖŞ; Overall Responsibility - ÖŞ.

Conflict of Interest

The authors have no conflicts of interest to declare

Financial Disclosure

The authors declared that this study has received no financial support.

References

  1. Von ungern Sternberg BS, Petak F, Saudan S, Pellegrini M, Erb TO, Habre W. Effect of cardiopulmonary bypass and aortic clamping on functional residual capacity and ventilation distribution in children. J Thorac Cardiovasc Surg 2007;134:1193-8.
  2. Boisseau N, Rabary O, Padovani B, Staccini P, Mouroux J, Grimaud D, et al. Improvement of ’dynamic analgesia’ does not decrease atelectasis after thoracotomy. Br J Anaesth 2001;87:564-9.
  3. Borges DL, Sousa LR, Silva RT, Gomes HC, Ferreira FM, Lima WL, et al. Pulmonary complications in pediatric cardiac surgery at a university hospital. Rev Bras Cir Cardiovasc 2010;25:234-7.
  4. Romanini W, Muller AP, Carvalho KA, Olandoski M, Faria-Neto JR, Mendes FL, et al. The effects of intermittent positive pressure and incentive spirometry in the postoperative of myocardial revascularization. Arq Bras Cardiol 2007;89:94-9.
  5. Giacomkazzi CM, Lagni VB, Monteiro MB. A dor posoperatoria como contribuinte do prejuízo na funçao pulmonar em pacientes submetidos a cirurgia cardiaca. Rev Bras Cir Cardiovasc 2006;21:386-92.
  6. Rolim DS, Galas FRB, Faria LS, Amorim EF, Regenga MM, Troster EJ. Use of noninvasive ventilation in respiratory failure after extubation during postoperative care in pediatrics. Pediatric Cardiology 2020;41:729-5.
  7. Odena MP, Marimbaldo IP, Matute SS, Argallo MB, Rico AP. Aplicacion de ventilacion no invasiva en pacientes postoperados cardiacos. Estudio retrospectivo. An Pediatr (Barc) 2009;71:13-9.
  8. Kubicka ZJ, Limauro J, Darnell RA. Heated humidified high-flow nasal cannula therapy: yet another way to deliver continuous positive airway pressure? Pediatrics 2008;121:82-8.
  9. Burra V, Lakshmi AS, Bhat AV, Prabhakar V, Manjunatha N. Comparison of high flow nasal cannula versus conventional oxygen therapy following extubation after pediatric cardiac surgery. Airway 2019;2:4-9.
  10. Hough JL, Pham TM, Schibler A. Physiologic effect of high-flow nasal cannula in infants with bronchiolitis. Pediatr Crit Care Med 2014;15:e214-9.
  11. Beggs S, Wong ZH, Kaul S, Ogden KJ, Walters JA. High flow nasal cannula therapy for infants with bronchiolitis. Cochrane Database Syst Rev 2014;20:1.
  12. Testa G, Iodice F, Ricci Z, Vitale V, De Razza F, Haiberger R, et al. Comparative evaluation of high flow nasal cannula and conventional oxygen therapy in pediatric cardiac surgical patients: a randomized controlled trial. Interact Cardiovasc Thorac Surg 2014;19:456-61.
  13. Yu I, Muneyuki T. Complex effects of high flow nasal cannula therapy on hemodynamics in the pediatric patient after cardiac surgery. J Intensive Care 2017;3:30.
  14. Finer NN, Bates R, Tomat P. Low flow oxygen delivery via nasal cannula to neonates. Pediatr Pulmonol 1996;21:48-51.
  15. Rittayamai N, Tscheikuna J, Rujiwit P. High flow nasal cannula versus conventional oxygen therapy after endotracheal extubation: a randomized crossover physiologic study. Respiratory Care 2014;59:485-90.
  16. Akyıldız B, Öztürk S, Tekerek NÜ, Doğanay S, Gör SB. Comparison between high flow nasal oxygen cannula and conventional oxygen therapy after extubation in pediatric intensive care unit. Turk J Pediatr 2018;60:126-3.
  17. Schibler A, Pham TM, Dunster KR, Foster K, Barlow A, Gibbons K, et al. Reduced intubation rates for infants after introduction of high flow nasal prong oxygen delivery. Intensive Care Med 2011;37:847-52.
  18. Campbell DM, Shah PS, Shah V, Kelly EN. Nasal continuous positive airway pressure from high flow cannula versus infant flow for preterm infants. J Perinatol 2006;26:546-9.
  19. Wernovsky G, Wypij D, Jonas RA, Majer Jr JE, Hanley FL, Hickey PR, et al. Postoperative course and hemodynamic profile after the arterial switch operation in neonates and infants. A comparison of low flow cardiopulmonary bypass and circulatory arrest. Circulation 1995;92:2226-35.
  20. Broncki RA, Penny DJ, Anas NG, Fuhrman B. Cardiopulmonary interactions. Pediatr Crit Care Med 2016;17:182-93.
  21. Parke RL, Bloch A, McGuinnes SP. Effect very high flow nasal therapy on airway pressure and end-expiratory lung impedance in healty volunteers. Respir Care 2015;60:1397-403.
  22. Green J, Walters HL, Delius RE, Sarnaik A, Mastropietro CW. Prevalence and risk factor for upper airway obstruction after pediatric cardiac surgery. J Pediatr 2015;66:332-7.
  23. Roca O, Riera J, Torres F, Masclans JR. High-flow oxygen therapy in acute respiratory failure. Respir Care 2010;55:408-13.
  24. Sztrymf B, Messika J, Mayot T, Lenglet H, Dreyfuss D, Ricard JD. Impact of high-flow nasal cannula oxygen therapy on intensive care unit patients with acute respiratory failure: a prospective observational study. J Crit Care 2012;27:324.
  25. Frizzola M, Miller T, Rodriguez ME, Zhu Y, Rojas J, Hesek A, et al. Highflow nasal cannula: Impact on oxygenation and ventilation in an acute lung injury model. Pediatr Pulmonol 2011;46:67-74.
  26. Yoo JW, Synn A, Huh JW, Hong SB, Koh Y, Lim CM. Clinical efficacy of high flow nasal cannula compared to noninvasive ventilation in patients with post-extubation respiratory failure. Korean J Intern Med 2016;31:82-8.
  27. Maggiore SM, Idone FA, Vaschetto R. Nasal high flow versus venturi mask oxygen therapy after extubation. Effects on oxygenation, comfort, and clinical outcome. Am J Respir Crit Care Med 2014;190:282-8.

Figure and Tables

Table 1. Demographic characteristics and baseline parameters
Table 2. Arterial oxygen tension (PaO2 ) at different time points
Table 3. Arterial carbon dioxide tension (PaCO2 ) at different time points
Table 4. PaO2 /FiO2 ratio at different time points
Table 5. Hemodynamic and respiratory parameters after extubation period