Management of adult-onset methylmalonic acidemia with hypotonia and acute respiratory failure: A case report.

RATIONALE: Methylmalonic acidemia (MMA) is an autosomal recessive disease of organic acidemia. PATIENT CONCERNS: We report a 26-year-old male who presented with metabolic acidosis, acute renal failure required hemodialysis and acute respiratory failure required mechanical ventilation support. Progressive hypotonia of muscles made weaning from mechanical ventilator difficult. DIAGNOSES: High level of serum methylmalonic acid and the mut genotype sequences confirmed the diagnosis of this adult-onset MMA. Two mut genotype sequences were found by analyzing all coding exons and exon-intron junctions. One genotype was well documented (Exon 6 Mutation, c. 1280G>A. p. G427D, heterozygous). The other mut genotype sequence had never been reported elsewhere (Intron 6 Novel, c. 1333-13_c. 1333-8delTTTTTC, heterozygous). INTERVENTIONS: Diet modification, medication, regular hemodialysis and physical rehabilitation. Weaning strategy adjusted with help of electrical impedance tomography. OUTCOMES: The muscle power of the patient gradually recovered. Extubation of the patient was successful and he was discharged without oxygen required. LESSONS: This case gives us the lesson that MMA can be newly diagnosed in adult patient. A new mut genotype sequence was discovered. The use of electrical impedance tomography to select a suitable method for inspiratory muscle training was possible and useful.

Regional ventilation redistribution measured by electrical impedance tomography during spontaneous breathing trial with automatic tube compensation.

OBJECTIVE: Automatic tube compensation (ATC) was developed to overcome the flow resistance of endotracheal tube and decrease the imposed work of breathing. Although ATC is used as an evidence-based strategy to predict successful weaning from assisted ventilation, the changes in regional ventilation distribution induced by this technique are not known. We hypothesized that continuous positive airway pressure plus ATC (CPAP + 100%ATC) could reactivate the respiratory muscles in patients with prolonged mechanical ventilation (PMV) more effectively than volume assist-control mandatory ventilation (ACMV). APPROACH: A total of 16 PMV patients were included. Patients were ventilated under volume ACMV mode and subsequently under CPAP + 100%ATC for 50 min. Two periods of 5 min electrical impedance tomography (EIT) data at the end of each mode were analyzed. MAIN RESULTS: Tidal variations of electrical impedance determined by EIT during CPAP + 100%ATC were significantly smaller than during ACMV (p < 0.001), while no significant differences in end-expiratory lung impedance were found. Regional ventilation was distributed significantly more towards dorsal regions during CPAP + 100%ATC as indicated by the EIT-based index center of ventilation (46.2 ± 5.8 during ACMV versus 51.7 ± 6.5 during CPAP + 100%ATC, values in %, p < 0.001). However, the overall degree of ventilation inhomogeneity was not improved as indicated by the global inhomogeneity index (0.42 ± 0.09 during ACMV versus 0.42 ± 0.06 during CPAP + 100%ATC). The onset of ventilation was significantly less delayed during CPAP + 100%ATC in both ventral and dorsal regions as indicated by the ventilation delay index (ACMV versus CPAP + 100%ATC, 53.0 versus 42.6 in ventral; 50.2 versus 39.3 in dorsal regions; values in %, p < 0.001). SIGNIFICANCE: Dorsal redistribution of ventilation and reduction of ventilation delay as identified by EIT indicate that CPAP + 100%ATC was effective in reactivating the respiratory muscles in the PMV patients of the present study.