Association of Passive Lung Insufflation Oxygen Fraction in Adult Patients on Cardiopulmonary Bypass with Postoperative Pulmonary Outcomes: A Retrospective Cohort Study.

OBJECTIVES: To determine whether FIO2 of passive lung insufflation during cardiopulmonary bypass correlates with postoperative pulmonary function. DESIGN: A retrospective, observational study SETTING: A single-center, university-affiliated, specialist cardiothoracic center in the United Kingdom. PARTICIPANTS: Adult patients presenting for nonemergency, nontransplant cardiac surgery requiring cardiopulmonary bypass without the need for deep hypothermic circulatory arrest between January 1, 2018, and December 31, 2018. INTERVENTIONS: Passive insufflation of the lungs during cardiopulmonary bypass with fresh gas flow of varying FIO2. Patients were sorted retrospectively into low FIO2 (0.21-0.44), intermediate FIO2 (0.45-0.69), and high FIO2 (0.7-1.0) groups. The primary outcome was the difference between the PaO2:FIO2 on the first postinduction blood gas and on the first blood gas recorded postoperatively in the intensive care unit (ICU) (delta PaO2:FIO2). Secondary outcomes were ICU and hospital lengths of stay, requirement for respiratory support, and 30-day mortality. MEASUREMENTS AND MAIN RESULTS: Nine hundred patients were included in the authors' analysis (low FIO2 n = 307, intermediate FIO2 n = 459, high FIO2 n = 134). There was no significant difference in delta PaO2:FIO2 among the groups (low FIO2 = 52.5 [-38.8 to 152.4], intermediate FIO2 = 71.8 [-39.4 to 165.1], high FIO2 = 60.2 [-19.2 to 184.0], p = 0.25). There were no significant differences among groups for any secondary outcomes. CONCLUSION: Fresh gas flow with a low FIO2 delivered to the lungs without positive airway pressure during cardiopulmonary bypass was not associated with improved postoperative pulmonary function when compared to higher FIO2 levels.

Lung Insufflation Capacity with a New Device in Amyotrophic Lateral Sclerosis: Measurement of the Lung Volume Recruitment in Respiratory Therapy.

OBJECTIVE: The aim of this study was to validate the usefulness of the measurement of lung insufflation capacity (LIC) using the LIC TRAINER (LT) in patients with amyotrophic lateral sclerosis (ALS). METHODS: This retrospective study was conducted in the rehabilitation departments of the Japanese National Center of Neurology and Psychiatry and involved 20 ALS patients who underwent respiratory therapy between April 1, 2014, and December 2017. The vital capacity (VC), maximum insufflation capacity (MIC), and LIC measurements at the start of respiratory therapy were extracted from the medical records, and patients were divided into three groups: group A, VC could not be measured; group B, VC could be measured, but MIC was less than VC; and group C, MIC was larger than VC. LIC could be measured in all groups. In group C, paired t-tests were used to analyze whether there was a significant difference in the volumes measured using different methods. RESULTS: LIC was 950, 1863±595, and 2980±1176 ml in groups A (n=1), B (n=10), and C (n=9), respectively. In groups A and B, LIC could be measured in all patients, even when VC or MIC could not be measured. In group C, the measured LIC value was significantly greater than MIC (p=0.003). CONCLUSION: LIC could be successfully measured using the LT. By using the LT, it was feasible to conveniently perform LIC measurements, suggesting that it could be a useful device for performing respiratory therapy in ALS patients.

Optimum insufflation capacity and peak cough flow in neuromuscular disorders.

RATIONALE: For patients with neuromuscular disorders, lung insufflation with positive pressure is an accepted technique to increase inspiratory volume over VC to improve peak cough flow (PCF). OBJECTIVES: The aim of the study was to determine the pressure or volume required to achieve the highest individual PCF. METHODS: In 40 patients dependent on noninvasive ventilation (VC, 16 ± 11% predicted; age, 20 ± 4 yr) and in 20 healthy control subjects, insufflation capacity (IC) was measured during titration from 10 to maximum 40 mbar using intermittent positive pressure breathing (IPPB) or the lung insufflation assist maneuver (LIAM) of the VENTIlogic LS ventilator. MEASUREMENTS AND MAIN RESULTS: IPPB or LIAM titration resulted in a pressure-volume curve with an estimated total compliance of 0.23 ± 0.11 L/kPa in the patients and 1.0 ± 0.3 L/kPa in the controls and a plateau for IC at pressures between 30 and 40 mbar. IPPB or LIAM improved VC from 451 ± 229 ml to a maximum IC (ICmax) of 1,027 ± 329 ml, and PCF improved from 109 ± 45 to 202 ± 62 L/min (P < 0.01 for all). The highest individual PCF was achieved with 27 ± 6 mbar and an IC of 924 ± 379 ml, which was significantly below ICmax (P < 0.01). CONCLUSIONS: A submaximal insufflation is ideal for generating the best individual PCF even in patients with severely reduced compliance of the respiratory system. Optimum insufflation capacity can be achieved using IPPB or LIAM with moderate pressures. Both techniques are equally effective and considered safe.

Artificial External Glottic Device for Passive Lung Insufflation

PURPOSE: For patients with neuromuscular disease, air stacking, which inflates the lungs to deep volumes, is important for many reasons. However, neuromuscular patients with severe glottic dysfunction or indwelling tracheostomy tubes cannot air stack effectively. For these patients, we developed a device that permits deep lung insufflations substituting for glottic function. MATERIALS AND METHODS: Thirty-seven patients with bulbar-innervated muscle weakness and/or tracheostomies were recruited. Twenty-three had amyotrophic lateral sclerosis, and 14 were tetraplegic patients due to cervical spinal cord injury. An artificial external glottic device (AEGD) was used to permit passive deep lung insufflation. In order to confirm the utility of AEGD, vital capacity, maximum insufflation capacity (MIC), and lung insufflation capacity (LIC) with AEGD (LICA) were measured. RESULTS: For 30 patients, MICs were initially zero. However, with the use of the AEGD, LICA was measurable for all patients. The mean LICA was 1,622.7+/-526.8 mL. Although MIC was measurable for the remaining 7 patients without utilizing the AEGD, it was significantly less than LICA, which was 1,084.3+/-259.9 mL and 1,862.9+/-248 mL, respectively (p<0.05). CONCLUSION: The AEGD permits lung insufflation by providing deeper lung volumes than possible by air stacking.