RESUMO
BACKGROUND: Widespread vaccinations have significantly decreased the number of tetanus cases in developed countries. Today, most cases of tetanus affect the elderly and those with inadequate immunization in developed countries such as Japan. As vaccinations were believed to be nearly 100% effective in preventing tetanus, tetanus in young, immunized individuals were considered unlikely. However, unexpected tetanus infection has been reported in young adequately immunized individuals. CASE: We herein describe a 20-year-old immunized female who visited our emergency department with trismus and painful muscle spasms that started after receiving a puncture wound to her right foot. A physical examination revealed an elevated body temperature (38°C), trismus, muscle spasms in her right leg and neck, and a puncture wound at the sole of her right foot. Following the development of dyspnea after admission to the intensive care unit, the patient was intubated and mechanically ventilated. She fully recovered after six days in intensive care. CONCLUSION: The present case serves as a stark reminder that tetanus may still occur in young, immunized individuals. Patients with a history of immunization may have a better prognosis than those with no immunizations.
RESUMO
BACKGROUND: Two recent large randomized controlled trials did not show the superiority of high-frequency oscillatory ventilation (HFOV) in adults with ARDS. These two trials had differing results, and possible causes could be the different oscillators used and their different settings, including inspiratory time % (IT%). The aims of this study were to obtain basic data about the ventilation characteristics in two adult oscillators and to elucidate the effect of the oscillator and IT% on ventilation efficiency. METHODS: The Metran R100 or SensorMedics 3100B was connected to an original lung model internally equipped with a simulated bronchial tree. The actual stroke volume (aSV) was measured with a flow sensor placed at the Y-piece. Carbon dioxide (CO2) was continuously insufflated into the lung model ([Formula: see text]CO2), and the partial pressure of CO2 (PCO2) in the lung model was monitored. Alveolar ventilation ([Formula: see text]A; L/min) was estimated as [Formula: see text]CO2 divided by the stabilized value of PCO2. [Formula: see text]A was evaluated with several stroke volume settings in the R100 (IT = 50%) or several airway pressure amplitude settings in the 3100B (IT = 33%, 50%) at a frequency of 6 and 8 Hz, a mean airway pressure of 25 cmH2O, and a bias flow of 30 L/min. Assuming that [Formula: see text]A = frequencya × aSVb, values of a and b were determined. Ventilation efficiency was calculated as [Formula: see text]A divided by actual minute ventilation. RESULTS: The relationship between aSV and [Formula: see text]A or ventilation efficiency were different depending on the oscillator and IT%. The values of a and b were 0 < a < 1 and 1 < b < 2 and were different for three conditions at both frequencies. [Formula: see text]A and ventilation efficiency were highest with R100 (IT = 50%) and lowest with 3100B (IT = 33%) for high aSV ranges at both frequencies. CONCLUSIONS: In this lung model study, ventilation characteristics were different depending on the oscillator and IT%. Ventilation efficiency was highest with R100 (IT = 50%) and lowest with 3100B (IT = 33%) for high aSV ranges.
RESUMO
BACKGROUND: Bias flow (BF) is essential to maintain mean airway pressure (MAP) and to washout carbon dioxide (CO2) from the oscillator circuit during high-frequency oscillatory ventilation (HFOV). If the BF rate is inadequate, substantial CO2 rebreathing could occur and ventilation efficiency could worsen. With lower ventilation efficiency, the required stroke volume (SV) would increase in order to obtain the same alveolar ventilation with constant frequency. The aim of this study was to assess the effect of BF rate on ventilation efficiency during adult HFOV. METHODS: The R100 oscillator (Metran, Japan) was connected to an original lung model internally equipped with a simulated bronchial tree. The actual SV was measured with a flow sensor placed at the Y-piece. Carbon dioxide (CO2) was continuously insufflated into the lung model ([Formula: see text]CO2), and the partial pressure of CO2 (PCO2) in the lung model was monitored. Alveolar ventilation ([Formula: see text]A) was estimated as [Formula: see text]CO2 divided by the stabilized value of PCO2. [Formula: see text]A was evaluated by setting SV from 80 to 180 mL (10 mL increments, n = 5) at a frequency of 8 Hz, a MAP of 25 cmH2O, and a BF of 10, 20, 30, and 40 L/min (study 1). Ventilation efficiency was calculated as [Formula: see text]A divided by the actual minute volume. The experiment was also performed with an actual SV of 80, 100, and 120 mL and a BF from 10 to 60 L/min (10 L/min increments: study 2). RESULTS: Study 1: With the same setting SV, the [Formula: see text]A with a BF of 20 L/min or more was significantly higher than that with a BF of 10 L/min. Study 2: With the same actual SV, the [Formula: see text]A and the ventilation efficiency with a BF of 30 L/min or more were significantly higher than those with a BF of 10 or 20 L/min. CONCLUSIONS: Increasing BF up to 30 L/min or more improved ventilation efficiency in the R100 oscillator.
