Repetitive postoperative extubation failure due to dynamic inspiratory airway collapse concomitant with subglottic stenosis in a patient who previously underwent tracheostomy.

BACKGROUND: This report describes a case of dynamic inspiratory airway collapse concomitant with subglottic stenosis in a patient who previously underwent tracheostomy that led to repeated post-operative extubation failure. CASE PRESENTATION: A 43-year-old woman who had undergone tracheostomy 25 years previously was admitted to our intensive-care unit (ICU) after coronary artery bypass graft surgery. On postoperative day (POD) 0, she was extubated, but stridor was observed. We suspected upper airway obstruction and she was therefore reintubated. Before reintubation, urgent laryngotracheoscopy revealed dynamic inspiratory airway collapse and obstruction concomitant with subglottic stenosis. Preoperative computed tomography showed mild subglottic stenosis. Although intravenous corticosteroids were administered to prevent tracheal mucosal edema and a cuff leak test was confirmed to be negative, she developed extubation failure on POD6. On POD12, we performed tracheostomy to reduce mechanical irritation from the endotracheal tube. Mechanical ventilation was withdrawn and she discharged from the ICU. On POD33, her tracheostomy tube was removed and she remained clinically asymptomatic. CONCLUSIONS: We should be aware of the history of tracheostomy, especially at high tracheostomy sites, even in the absence of respiratory symptoms as risk factors for dynamic inspiratory airway collapse concomitant with subglottic stenosis contributing to repeated respiratory failure after extubation. J. Med. Invest. 70 : 301-305, February, 2023.

The quality and quantity of sleep on dexmedetomidine during high-flow nasal cannula oxygen therapy in critically ill patients.

Purpose : High-flow nasal cannula oxygen therapy (HFNC) is a new type of non-invasive respiratory support for acute respiratory failure patients. However, patients receiving HFNC often develop sleep disturbances. We therefore examined whether dexmedetomidine could preserve the sleep characteristics in patients who underwent HFNC. Patients and Methods : This was a pilot, randomized controlled study. We assigned critically ill patients treated with HFNC to receive dexmedetomidine (0.2 to 0.7 µg / kg / h, DEX group) or not (non-DEX group) at night (9:00 p.m. to 6:00 a.m.). Polysomnograms were monitored during the study period. The primary outcomes were total sleep time (TST), sleep efficiency and duration of stage 2 non-rapid eye movement (stage N2) sleep. Results : Of the 28 patients who underwent randomization, 24 were included in the final analysis (12 patients per group). Dexmedetomidine increased the TST (369 min vs. 119 min, p = 0.024) and sleep efficiency (68% vs. 22%, P = 0.024). The duration of stage N2 was increased in the DEX group compared with the non-DEX group, but this finding did not reach statistical significance. The incidences of respiratory depression and hemodynamic instability were similar between the two groups. Conclusions : In critically ill patients who underwent HFNC, dexmedetomidine may optimize the sleep quantity without any adverse events. J. Med. Invest. 69 : 266-272, August, 2022.

Acquired laryngomalacia as a cause of post-extubation respiratory failure in patient with postoperative seizure and central pontine myelinolysis after craniotomy.

Background : Laryngomalacia is a congenital abnormality of the larynx that commonly occurs in children and rarely in adults. We report the first case of acquired laryngomalacia mainly due to postoperative seizure and central pontine myelinolysis after scheduled craniotomy. Case presentation : A 69-year-old man was admitted to the hospital for elective craniotomy for craniopharyngioma. After the surgery, he developed refractory seizure and required intubation and mechanical ventilation in the intensive-care unit (ICU). After treatment for the seizure, he was extubated. However, immediately after extubation, he developed stridor and respiratory retraction. We performed fiberoptic laryngoscopy and confirmed that the epiglottis had collapsed into the posterior wall of the pharynx during inspiration, which was suspected to be laryngomalacia. He received invasive mechanical ventilation for two days following re-extubation. After the second extubation, he developed stridor again due to acquired laryngomalacia. Six days later, his respiratory condition had worsened, and he received re-intubation and tracheostomy. After ICU discharge, central pontine myelinolysis was diagnosed by magnetic resonance imaging. Conclusions : Adult-onset laryngomalacia is a rare cause of upper airway obstruction but should be considered as a cause of postoperative extubation failure. We should not delay performing fiberoptic laryngoscopy to evaluate this pathology and provide optimal treatment. J. Med. Invest. 69 : 316-319, August, 2022.

Independent lung ventilation for the management of acute allograft rejection after single-lung transplantation for end-stage emphysema.

Background : We herein report the use of independent lung ventilation (ILV) for managing acute allograft rejection after single-lung transplantation (SLT) for end-stage emphysema. Case presentation : A 54-year-old woman was transferred to our hospital with severe hypoxemia and respiratory distress due to unilateral lung disease with diffuse alveolar damage in the right donor lung associated with acute allograft rejection and with hyperinflation of the left native lung due to emphysema. She was unresponsive to immunosuppressive medications and conventional ventilation strategies, so different ventilator settings for each lung were required. A double-lumen endotracheal tube (DLT) was inserted, and ILV was initiated. The right lung was ventilated with high positive end-expiratory pressure (PEEP), intended for lung recruitment, and the left lung was ventilated with lung protective strategies using a low tidal volume and low levels of PEEP to avoid hyperinflation. Two days later, her lung function was dramatically improved, and the DLT was replaced with a single-lumen endotracheal tube. Gas exchange was maintained, and she was successfully weaned from mechanical ventilation on intensive-care unit day 15. Conclusions : ILV appears to be effective and safe for managing acute allograft rejection after SLT for emphysema. J. Med. Invest. 69 : 323-327, August, 2022.

Relationships between double cycling and inspiratory effort with diaphragm thickness during the early phase of mechanical ventilation: A prospective observational study.

BACKGROUND: Increased and decreased diaphragm thickness during mechanical ventilation is associated with poor outcomes. Some types of patient-ventilator asynchrony theoretically cause myotrauma of the diaphragm. However, the effects of double cycling on structural changes in the diaphragm have not been previously evaluated. Hence, this study aimed to investigate the relationship between double cycling during the early phase of mechanical ventilation and changes in diaphragm thickness, and the involvement of inspiratory effort in the occurrence of double cycling. METHODS: We evaluated adult patients receiving invasive mechanical ventilation for more than 48 h. The end-expiratory diaphragm thickness (Tdiee) was assessed via ultrasonography on days 1, 2, 3, 5 and 7 after the initiation of mechanical ventilation. Then, the maximum rate of change from day 1 (ΔTdiee%) was evaluated. Concurrently, we recorded esophageal pressure and airway pressure on days 1, 2 and 3 for 1 h during spontaneous breathing. Then, the waveforms were retrospectively analyzed to calculate the incidence of double cycling (double cycling index) and inspiratory esophageal pressure swing (ΔPes). Finally, the correlation between double cycling index as well as ΔPes and ΔTdiee% was investigated using linear regression models. RESULTS: In total, 19 patients with a median age of 69 (interquartile range: 65-78) years were enrolled in this study, and all received pressure assist-control ventilation. The Tdiee increased by more than 10% from baseline in nine patients, decreased by more than 10% in nine and remained unchanged in one. The double cycling indexes on days 1, 2 and 3 were 2.2%, 1.3% and 4.5%, respectively. There was a linear correlation between the double cycling index on day 3 and ΔTdiee% (R2 = 0.446, p = 0.002). The double cycling index was correlated with the ΔPes on days 2 (R2 = 0.319, p = 0.004) and 3 (R2 = 0.635, p < 0.001). CONCLUSIONS: Double cycling on the third day of mechanical ventilation was associated with strong inspiratory efforts and, possibly, changes in diaphragm thickness.

Effect of controlled ventilation during assist-control ventilation on diaphragm thickness†:†a post hoc analysis of an observational study.

Background : Since diaphragm passivity induces oxidative stress that leads to rapid atrophy of diaphragm, we investigated the effect of controlled ventilation on diaphragm thickness during assist-control ventilation (ACV). Methods : Previously, we measured end-expiratory diaphragm thickness (Tdiee) of patients mechanically ventilated for more than 48 hours on days 1, 3, 5 and 7 after the start of ventilation. We retrospectively investigated the proportion of controlled ventilation during the initial 48-hour ACV (CV48%). Patients were classified according to CV48% : Low group, less than 25% ; High group, higher than 25%. Results : Of 56 patients under pressure-control ACV, Tdiee increased more than 10% in 6 patients (11%), unchanged in 8 patients (14%) and decreased more than 10% in 42 patients (75%). During the first week of ventilation, Tdiee decreased in both groups : Low (difference, -7.4% ; 95% confidence interval [CI], -10.1% to -4.6% ; p < 0.001) and High group (difference, -5.2% ; 95% CI, -8.5% to -2.0% ; p = 0.049). Maximum Tdiee variation from baseline did not differ between Low (-15.8% ; interquartile range [IQR], -22.3 to -1.5) and High group (-16.7% ; IQR, -22.6 to -11.1, p = 0.676). Conclusions : During ACV, maximum variation in Tdiee was not associated with proportion of controlled ventilation higher than 25%. J. Med. Invest. 67 : 332-337, August, 2020.

Effect of High-Flow Nasal Cannula on Sleep-disordered Breathing and Sleep Quality in Patients With Acute Stroke.

Introduction Sleep-disordered breathing (SDB) is common after stroke. Although the standard treatment of SDB is continuous positive airway pressure (CPAP) ventilation, the patient's intolerance and discomfort result in low adherence rates. Alternatively, high-flow nasal cannula (HFNC) may be useful as it reduces upper airway collapse with low level of positive pressure and well tolerability. The aim of this study was to investigate whether HFNC therapy reduces SDB and improves sleep quality with higher compliance rate. Methods We included acute stroke patients with SDB for the assessment of apnea-hypopnea index (AHI) >5/h using WatchPAT 200 (Itamar Medical Ltd, Caesarea, Israel). Patients who met inclusion criteria received HFNC therapy (40 L/min) with monitoring by WatchPAT. AHI, oxygen desaturation index (ODI), sleep efficiency, and rapid eye movement (REM) sleep were compared in patients with and without HFNC therapy. We also evaluated the patient's comfort of HFNC therapy (discomfort or not). Results Among 17 patients assessed for AHI, 12 received HFNC therapy. HFNC therapy was not adhered in two patients due to intolerance. Eight patients remained for final analysis. There were no differences in SDB and sleep quality with and without HFNC therapy as follows: HFNC therapy vs control; AHI 24.9 ± 20.1 vs 21.3 ± 15.0/h (p = 0.63), ODI 16.2 ± 16.5 vs 12.9 ± 12.3/h (p = 0.54), sleep efficiency 80.4 ± 12.9 vs 87.1 ± 6.2 (p = 0.28), percentage of REM sleep 19.4% ± 9.6% vs 27.6% ± 8.9% (p = 0.07). Two patients (17%) complained of discomfort among eight patients. Conclusion HFNC therapy did not improve SDB and sleep quality. Nonadherence and discomfort were observed in HFNC therapy. We need a large trial to confirm this result.

Neurally adjusted ventilatory assist improves patient-ventilator synchrony in a patient with tetanus and unstable diaphragmatic electrical activity.

A 79-y-old man with generalized tetanus was admitted to the ICU. A left-forearm wound was surgically debrided, and the wound was closed. On postoperative day 1, after the patient experienced opisthotonos and convulsions, endotracheal intubation was performed. Propofol and diazepam were infused but failed to stop the convulsions. Morphine, midazolam, dantrolene, and rocuronium were used to ameliorate the muscle spasms. Magnesium sulfate was also infused. On postoperative day 15, patient-ventilator asynchrony was apparent. The patient showed recurrent tachypnea and bradypnea, which seemed typical of Cheyne-Stokes respiration. A neurally adjusted ventilatory assist (NAVA) catheter was inserted transnasally, and electrical activity of the diaphragm (Edi) was monitored. Readings showed regular attempts to breathe at 40-50 breaths/min with periodic changes in Edi amplitude. NAVA mode improved patient-ventilator synchrony. Periodic breathing continued for 2 weeks. We stopped monitoring Edi on postoperative day 39. He began respiratory rehabilitation and was transferred to a hospital for rehabilitation on postoperative day 80. We encountered periodic respiration in a patient with tetanus. Edi monitoring revealed periodic amplitude change. The cause of the periodic breathing pattern in this patient could not be determined but may be attributable to side effects of the pharmacologic interventions or the natural history of the disease itself. NAVA mode improved patient-ventilator synchrony.