A narrative review of advanced ventilator modes in the pediatric intensive care unit

Acute Respiratory Distress Syndrome, Mechanical Ventilation, and Inhalation Injury in Burn Patients

Respiratory failure occurs with some frequency in seriously burned patients, driven by a combination of inflammatory and infection factors. Inhalation injury contributes to respiratory failure in some burn patients via direct mucosal injury and indirect inflammation. In burn patients, respiratory failure leading to acute respiratory distress syndrome, with or without inhalation injury, is effectively managed using principles evolved for non-burn critically ill patients.

A Delphi Survey of Canadian Respiratory Therapists' Practice Statements on Pediatric Mechanical Ventilation

BACKGROUND

Pediatric mechanical ventilation practice guidelines are not well established; therefore, the European Society for Paediatric and Neonatal Intensive Care (ESPNIC) developed consensus recommendations on pediatric mechanical ventilation management in 2017. However, the guideline's applicability in different health care settings is unknown. This study aimed to determine the consensus on pediatric mechanical ventilation practices from Canadian respiratory therapists' (RTs) perspectives and consensually validate aspects of the ESPNIC guideline.

METHODS

A 3-round modified electronic Delphi survey was conducted; contents were guided by ESPNIC. Participants were RTs with at least 5 years of experience working in standalone pediatric ICUs or units with dedicated pediatric intensive care beds across Canada. Round 1 collected open-text feedback, and subsequent rounds gathered feedback using a 6-point Likert scale. Consensus was defined as ≥ 75% agreement; if consensus was unmet, statements were revised for re-ranking in the subsequent round.

RESULTS

Fifty-two RTs from 14 different pediatric facilities participated in at least one of the 3 rounds. Rounds 1, 2, and 3 had a response rate of 80%, 93%, and 96%, respectively. A total of 59 practice statements achieved consensus by the end of round 3, categorized into 10 sections: (1) noninvasive ventilation and high-flow oxygen therapy, (2) tidal volume and inspiratory pressures, (3) breathing frequency and inspiratory times, (4) PEEP and F_IO2 , (5) advanced modes of ventilation, (6) weaning, (7) physiological targets, (8) monitoring, (9) general, and (10) equipment adjuncts. Cumulative text feedback guided the formation of the clinical remarks to supplement these practice statements.

CONCLUSIONS

This was the first study to survey RTs for their perspectives on the general practice of pediatric mechanical ventilation management in Canada, generally aligning with the ESPNIC guideline. These practice statements considered information from health organizations and institutes, supplemented with clinical remarks. Future studies are necessary to verify and understand these practices' effectiveness.

2021 Year in Review: Pediatric Mechanical Ventilation

Mechanical ventilation is commonly used in the pediatric intensive care unit. This paper reviews studies of pediatric mechanical ventilation published in 2021. Topics include physiology, ventilator modes, alarms, disease states, airway suctioning, ventilator liberation, prolonged ventilation, and others.

High-Frequency Percussive Ventilation in Viral Bronchiolitis

BACKGROUND

High-frequency percussive ventilation (HFPV) is an alternative mode of mechanical ventilation that has been shown to improve gas exchange in subjects with severe respiratory failure. We hypothesized that HFPV use would improve ventilation and oxygenation in intubated children with acute bronchiolitis.

METHODS

In this single-center prospective cohort study we included mechanically ventilated children in the pediatric ICU with bronchiolitis 1-24 months old who were transitioned to HFPV from conventional invasive mechanical ventilation from November 2018-April 2020. Patients with congenital heart disease, on extracorporeal membrane oxygenation (ECMO), and with HFPV duration < 12 h were excluded. Subject gas exchange metrics and ventilator parameters were compared before and after HFPV initiation.

RESULTS

Forty-one of 192 (21%) patients intubated with bronchiolitis underwent HFPV, and 35 met inclusion criteria. Median age of cohort was 4 months, and 60% were previously healthy. All subjects with available oxygenation saturation index (OSI) measurements pre-HFPV met pediatric ARDS criteria (31/35, 89%). Mean CO2 decreased from 65.4 in the 24 h pre-HFPV to 51 (P < .001) in the 24 h post initiation. SpO2 /FIO2 was significantly improved at 24 h post-HFPV (153.3 to 209.7, P = .001), whereas the decrease in mean OSI at 24 h did not meet statistical significance (11.9 to 10.2, P = .15). The mean peak inspiratory pressure (PIP) decreased post-HFPV from 29.7 to 25.0 at 24 h (P < .001). No subjects developed an air leak or hemodynamic instability secondary to HFPV. Two subjects required ECMO, and of these, one subject died.

CONCLUSIONS

HFPV was associated with significant improvement in ventilation and decreased exposure to high PIPs for mechanically ventilated children with bronchiolitis in our cohort and had a potential association with improved oxygenation. Our study shows that HFPV may be an effective alternative mode of ventilation in patients with bronchiolitis who have poor gas exchange on conventional invasive mechanical ventilation.

The Physiological Basis of High-Frequency Oscillatory Ventilation and Current Evidence in Adults and Children: A Narrative Review

High-frequency oscillatory ventilation (HFOV) is a type of invasive mechanical ventilation that employs supra-physiologic respiratory rates and low tidal volumes (V_T) that approximate the anatomic deadspace. During HFOV, mean airway pressure is set and gas is then displaced towards and away from the patient through a piston. Carbon dioxide (CO₂) is cleared based on the power (amplitude) setting and frequency, with lower frequencies resulting in higher V_T and CO₂ clearance. Airway pressure amplitude is significantly attenuated throughout the respiratory system and mechanical strain and stress on the alveoli are theoretically minimized. HFOV has been purported as a form of lung protective ventilation that minimizes volutrauma, atelectrauma, and biotrauma. Following two large randomized controlled trials showing no benefit and harm, respectively, HFOV has largely been abandoned in adults with ARDS. A multi-center clinical trial in children is ongoing. This article aims to review the physiologic rationale for the use of HFOV in patients with acute respiratory failure, summarize relevant bench and animal models, and discuss the potential use of HFOV as a primary and rescue mode in adults and children with severe respiratory failure.

High-Frequency Jet Ventilation in Infants With Congenital Heart Disease

BACKGROUND

High-frequency jet ventilation (HFJV) is primarily used in neonates but may also have a role in the treatment of infants with congenital heart disease and severe respiratory failure. We hypothesized that HFJV would result in improved gas exchange in these infants.

METHODS

We retrospectively reviewed the records of all pediatric patients with complex congenital heart disease treated HFJV in our pediatric cardiac ICU between 2014 and 2018. Patients in whom HFJV was started while on extracorporeal membrane oxygenation (ECMO) were excluded. We extracted data on demographics, pulmonary mechanics, gas exchange, the subsequent need for ECMO, use of inhaled nitric oxide, and outcomes.

RESULTS

We included 27 subjects (median [interquartile range {IQR}] weight 4.4 [3.3-5.4] kg; median [IQR] age 2.5 [0.3-5.4] months), 22 (82%) of whom had cyanotic heart disease. Thirteen subjects (48%) survived and 6 (22%) required ECMO. HFJV was started after a median (IQR) of 8.4 (2.1-26.3) d of conventional mechanical ventilation. The subjects spent a median (IQR) of 1.2 (0.5-2.8) d on HFJV. The median (IQR) pre-HFJV blood gas results (n = 25) were pH 7.22 (7.17-7.31), [Formula: see text] 69 (51-77) mm Hg, and [Formula: see text] 51 (41-76) mm Hg. Median (IQR) initial HFJV settings were peak inspiratory pressure of 45 (36-50) cm H₂O, breathing frequency of 360 (360-380) breaths/min, and inspiratory time of 0.02 (0.02-0.03) s. Compared with conventional mechanical ventilation, at 4-6 h after HFJV initiation, there were significant improvements in the median pH (7.22 vs 7.34; P = .001) and [Formula: see text] (69 vs 50 mm Hg; P = .001), respectively, but no difference in median [Formula: see text] (51 vs 53 mm Hg; P = .97).

CONCLUSIONS

HFJV was associated with a decrease in [Formula: see text] and an increase in pH in infants with congenital heart disease who remained on HFJV 4 to 6 h after initiation.