A Case of Hypercapnic Respiratory Failurein a Patient with Eosinophilic Polymyositis / 대한류마티스학회지

Eosinophilic infiltration into skeletal muscles has been rarely reported in a variety of conditions such as parasite infection, sarcoidosis, rheumatoid arthritis, eosinophilia-myalgia syndrome, and idiopathic hypereosinophilic syndrome. Eosinophilic myositis (EM) is one of idiopathic inflammatory muscle diseases associated with muscle and/or blood eosiophilia. The case of EM complicated with hypercapnic respiratory failure has been extremely rarely reported. A 61-year-old woman was admitted with sudden-onset pain in both calves. She had elevated serum muscle enzymes and peripheral eosinophil count. Findings of electromyography were consistent with inflammatory myopathy. MRI showed diffuse hyperintensity of calf muscles on T2-weighted and enhanced T1 images. Muscle biopsy showed eosinophils' infiltration in the endomysium and perivascular area. During the diagnostic work-up, she presented with hypercapnic respiratory failure. She was successfully treated with mechanical ventilation and high doses of prednisolone. This case suggests EM can cause respiratory failure secondary to respiratory muscle involvement.

Mechanical Ventilation of the Children / 소아과

Mechanical ventilation in children has some differences compared to in neonates or in adults. The indication of mechanical ventilation can be classified into two groups, hypercapnic respiratory failure and hypoxemic respiratory failure. The strategies of mechanical ventilation should be different in these two groups. In hypercapnic respiratory failure, volume target ventilation with constant flow is favorable and pressure target ventilation with constant pressure is preferred in hypoxemic respiratory failure. For oxygenation, fraction of inspired oxygen (FiO2) and mean airway pressure (MAP) can be adjusted. MAP is more important than FiO2. Positive end expiratory pressure (PEEP) is the most potent determinant of MAP. The optimal relationship of FiO2 and PEEP is PEEP = FiO2 x 20. For ventilation, minute volume of ventilation (MV) product of tidal volume (TV) and ventilation frequency is the most important factor. TV has an maximum value up to 15 mL/kg to avoid the volutrauma, so ventilation frequency is more important. The time constant (TC) in children is usually 0.15-0.2. Adequate inspiratory time is 3TC, and expiratory time should be more than 5TC. In some severe respiratory failure, to get 8TC for one cycle is impossible because of higher frequency. In such case, permissive hypercapnia can be considered. The strategy of mechanical ventilation should be adjusted gradually even in the same patient according to the status of the patient. Mechanical ventilators and ventilation modes are progressing with advances in engineering. But the most important thing in mechanical ventilation is profound understanding about the basic pulmonary mechanics and classic ventilation modes.

COPD Patients with Hypercapnic Respiratory Failure: Response to Therapy and Determinant of Intubation / 결핵

BACKGROUND: The determinants of intubation and the response to therapy in COPD patients with hypercapnic respiratory failure were retrospectively reviewed. METHODS: This study involved a review of 132 episodes of hypercapnic respiratory failure(PaCO2≥50mmHg and pH≤7.35). The time frame for resolution or the time to intubation of patients who were admitted between 1996 and 1999 was analyzed. RESULTS: Out of 132 hypercapnic episodes, 49(37%) required intubation. A comparison was made with the 83 cases that responded to treatment. Patients requiring intubation had greater severity of illness, which included a higher APACHE II (Acute Physiology and Chronic Health Evaluation II) score (20±5 vs 14±4 ; p<0.01), a higher WBC, a higher serum BUM, and greater acidosis (pH, 7.23±0.11 vs 7.32±0.04 ; p<0.01). Those with the most severe acidosis(pH<7.20) had the highest intubation rate(87%) and shortest time to intubation (2±3 h). Conversely, those with an initial pH 7.31 to 7.35 were less likely to be intubated(20%), and had a longer time to intubation(97±121 h). The patients with a pH 7.21 to 7.25(4.1±2.9 day) required longer period of time to respond to medical treatment than patients with a pH of 7.31 to 7.35(2.2±3.1 day). Of those patients requiring intubation, half(55%) were intubated within 8 h of admission, and most (75%) within 24 h. Of those patients responding to treatment medical therapy, half(52%) recovered within 24 h and most (78%) recovered within 48 h. CONCLUSION: Respiratory acidosis at the initial presentation is associated with an increased likelihood of intubation. This shold assist in deciding help with the decision whether to treat patients medically, institute noninvasive ventilation, or proceed to intubation.