Here, we report that NIV was effective and safe in treating respiratory failure in critically ill children, with only 13 patients dying post administration. Patients with successful NIV required fewer inotropic drugs, had shorter PICU stays, and lower mortality rates during the follow up. NIV-PSV and NIV-PCV were used more frequently in the failed groups. NIV associated complications were higher in the failure group.
in the last 20 years, NIV for critically ill infants and children has gradually increased, in providing non-invasive pressure support to the lungs during inspiration without endotracheal intubation. Endotracheal intubation is an invasive procedure involving a number of risks and negative consequences, including ventilator-associated pneumonia and mechanical damage [9-11]. Additionally, NIV improves blood gas test results and reduces respiratory rate, frequency of intubation, length of hospital stay, and mortality [10,11]. Therefore, it is routinely practiced in PICUs. Recently, HFNC has been used as a respiratory support and several studies report its significant efficacy in infants [12,13]. In HFNC positive pressure is applied at the end of the expiration to avoid alveolar collapse, decreasing the effort of inspiration [14,15]. Additionally, TV is provided by the applied positive inspiratory pressure. Another advantage is the constant and higher FiO2 supported by NIV. Although HFNC cannot accomplish each component, positive airway pressure from the nasopharynx to the alveoli may simulate the effect of high flow .
Here, we used HFNC and NIV. Patients were selected based on their age and clinical condition. NIV-PSV and NIV-PCV were preferred in patients with concomitant chronic disease and organ failure (Table II). Although the HFNC group had a higher PRISM III score, they were not statistically correlated. Despite the high success rates of all three methods, that of HFNC was significantly higher, possibly due to the presence of concomitant diseases and organ failure. Furthermore, a recent retrospective study demonstrated that HFNC might be associated with lower post-cardiac surgery reintubation rates than NIV in children . This difference was attributed to reduced dead space and respiratory workload. Contrarily, NIV increases dead space , requiring a more controlled ventilation, subsequently increasing the breathing workload.
A study previously reported that the presence of a chronic diseases affects outcomes of NIV administration . Here, 44.9% of patients presented prior comorbidities, particularly neurologic or metabolic diseases. In the 50 neurological-metabolic sequelae patients from the NIV group, 14 (28%) had failed NIV. Another pediatric study identified a higher failure rate among patients with a history of neurological diseases, attributed to pharyngeal hypotonia and poor airway protection . However, here, the frequency of aspiration did not increase in the neurologic-metabolic patient group. The lower incidence of aspiration may be due to the insertion of a nasogastric catheter in these patients. Additionally, we did not feed patients first hours before decreasing work of breathing.
Several factors possibly affect the success or failure of NIV, such as the NIV indication, severity and type of the respiratory failure, the timing of NIV implementation; and the expertise of the health care team [7,20]. Follow-up was performed according to NIV protocol. Routine blood gas was taken at the second hour, and was monitored every 4 hours on the first day. Therefore, the success rates in the patients receiving NIV therapy in our study was similar to those observed literatures [6,20].
It has been reported that the first few hours of the NIV is crucial for its success [7, 13]; therefore, we carefully monitored the blood gas values along with the respiratory and cardiac signs. The blood gas control from the patients at the second hour were taken according to the NIV protocol. However, there was no relationship between NIV failure and the vital signs. Contrary to our study, previous studies demonstrate that respiratory rate , SpO2 (particularly SpO2/FiO2 ratio) , and heart rate during NIV usage were independent predictors of success.
In a prospective adult study showed that failure of NIV was associated with an increased risk of mortality and hospital stay . In this study, patients that failed had higher rates of mortality. It was suggested that patients with higher mortality score would need closer monitoring during NIV. Another multicenter study involving a wider patient group, reported an increase in mortality with increase NIV failure rates , similar to the results of our study. Furthermore, 3 of the 5 HFNC patients who died were in the failed group, this group was also associated with significantly higher rates of organ failure and PRISM III score. Logistic regression analysis revealed that NIV and HFNC failure increased the PICU mortality 19 times in our study, indicating that this failure may be associated with more serious disease and mortality. Additionally, NIV failure patients also experienced higher rates of serious complications. Several studies have reported that NIV failure showed significant correlation with PRISM III score [24, 25], contrary to our NIV patients. However, our study reports a significant relationship between HFNC failure and PRISM III score.
Generally, NIV and HFNC are relatively safe strategies to treat respiratory failure in children. Complications include gastric distention, eye irritation, air leak (e.g. pneumothorax), and delayed intubation . Here, the most serious complications were pneumothorax and aspiration of gastrointestinal contents. One of the three patients with pneumothorax was suffering from meningococcemia, the second from brain abscess and the third from Duchenne muscular dystrophy. Patient with meningococcemia subsequently died due to concomitant surgical wounds and nosocomial sepsis (Acinetobacter baumannii). The Duchenne muscular dystrophy patient underwent tracheostomy. Here, the most common complication was skin pressure lesions that have been reported in 4–27% of children in previous studies . There was no severe skin necrosis.
Most studies do not recommend the use of sedatives, since the patients’ agitation may be a manifestation of the significant hypoxia or the increased breathing strain . Therefore, if sedation were to be performed, the drugs must not suppress the central respiratory drive and the protective airway reflexes [20,27]. After appropriate mask and trigger sensitivity adjustment, the patients were sedated with midazolam or ketamine. Dexmedetomidine, ketamine, and midazolam infusions were started in the patients presenting continued agitation. Ketamine infusion was particularly used in asthmatic patients. Our aim was to prevent asynchrony. The success of NIV and HFNC was similar to previous studies despite using sedatives [9, 22]. Therefore, low sedation doses do not adversely affect NIV success. However, the effect of sedation could not be evaluated in this study.
This study has a number of limitations, the first being that this was a retrospective and had limited number of patients. Concomitant medication, blood gas values, and sedation were not evaluated. Due to their observational nature, these results should be investigated further in randomized controlled trials. The strengths of our study are that the data was acquired from two centers, combination of HFNC and NIV, and the small number of similar studies in pediatric health. Additionally, our study included patients with varied characteristics and conditions.