The Comparison Of Two Different Ventilation Modes In Mechanical Ventilation Patients With COPD

Objective: Mechanical ventilation is mainly used on patients with acute or chronic respiratory failure and respiratory insufficiency caused by various reasons, and one of its important targets is to provide effective and comfortable venting support safely. Chronic obstructive pulmonary disease(COPD) is a severity respiratory passage disease which has a key feature of obstructive airway, and infection or other reasons may lead to its acute exacerbation and make the mechanical ventilation support necessarily. But the positive pressure ventilation can make the intrathoracic pressure raised and cause a series complication accordingly, also include the ventilation associated pneumonia caused by secondary infection of tracheal intubation. Meanwhile, if installation of parameter is unsuitable or patient- ventilator dyssynchrony is happening, that may lead to patients, respiratory muscle disused or tired, and the two states all can make patients depending on machine and make the extubate difficult.During the partial ventilation support, patients can breathe spontaneously, and share the work of breathing(WOB) with machines in common, accordingly the disuse atrophy of respiratory muscle is evitable because of the muscle,s movement, adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation plus inspiratory pressure support (SIMV+PSV) belong to partial ventilation support. The development of ASV is on the basis of min-WOB principle, it uses the microcomputer handle control system to monitor the patient,s immediate situation, then by the self-adjusting of machine parameters to suit patient,s breath requirement, so the change from complete ventilation support to partial ventilation support is automatic, even it can guide patient into extubate stage, in principle the respiratory muscle disuse atrophy or tired is evitable, so it makes extubate early.By using the ASV and SIMV+PSV to mechanical ventilation patients with COPD, we observed the changes of respiratory mechanics, haemodynamics and blood gas analysis between the two ventilation modes and the routine mode of assist/control (A/C). Meanwhile we evaluated whether ASV has superiorty for extubate to the routine mode of SIMV+PSV.Methods: When the patient was on the acute exacerbation stage of COPD and the mechanical ventilation was necessary, he will be given mechanical ventilation by nasotracheal tube or oral trachea cannula, using the A/C mode in the initial stage, and after four to twelve hours the mode was changed into ASV or SIMV+PSV mode in random when the patient,s condition was stable. Every patient was rechecked blood gas analysis after the mode was changed 30min, and machine index was adjusted according to the result of blood gas analysis and machine monitored window. Before mode was changed and two hours after mode was changed, we should record these indexes of every patient, such as respiratory rate (RR), tidal volume (VT), peak airway pressure (Ppeak), mean airway pressure (Pmean), inspiratory resistance (Rinsp), expiratory resistance (Rexp), airway occlusion pressure (P0.1), static compliance (C), and rapid shallow breathing index (RSB), heart rate (by electrocardiogram monitor), mean arterial pressure (calculated by arterial blood pressure, MAP) and pH, PaCO2 and PaO2. When the standard of extubate achieved, he will be extubated and given non-invasion ventilation by oral-nasal mask. According to patient,s respiratory function and blood gas analysis result, non-invasion ventilator was used interruptablely up to the patient,s weaning from ventilation support completely. The regulation times during SIMV+PSV or ASV stage, duration of invasion ventilation, duration of non-invasion ventilation, achievement ratio of extubate were recorded.Statistics methods: Measurement date(moral distribution) was expressed as mean±SEM, self comparison was made by pair t-test, interblock contrast was analyzed by group t-test and comparison of ratio was analyzed byκ2-test using SAS 6.12 software. P<0.05 was considered statistically significant.Results: 1 The effect to breathing mechanics index by different ventilation modes: (1) When the mode was changed into ASV, patients, VT raised and RR descended(P<0.01), but no significant change for the Rinsp and Rexp. When the mode was changed into SIMV+PSV, patients, RR descended(P<0.01), and the change of VT, Rinsp and Rexp were not statistically significant. (2) All patients, Ppeak and Pmean descended (P<0.01), no matter which mode was changed into. (3) When the mode was changed into ASV, patients, P0.1 and RSB descended (P<0.01), and C raised(P<0.01). When the mode was changed into SIMV+PSV, patients, P0.1 and RSB descended (P<0.01), but the C was not different significantly.2 The effect to blood gas analysis: All patients, changes of pH, PaCO2 and PaO2 were not different significantly, no matter which mode was changed into.3 The effect to haemodynamics: All patients, changes of HR and MAP were not different significantly, no matter which mode was changed into.4 The comparison of other parameters: The duration of invasion ventilation and the duration of non-invasion ventilation were not statistically significant between the two group(P>0.05). But the regulation times during using ASV were fewer(P<0.01).5 All patients were extubated successfully, and the achievement ratio were all 100%, there were not statistically significant.Conclusion: 1 Compared with conventional ventilation mode of A/C, patients, RR degraded but VT and C increased during using ASV mode, these changes may fit the physiological need more of patients with COPD, making them feel more comfortable. Meanwhile, alveolar effective ventilation should be improved by extended inspiratory time and expiration time, and this made for degrading work of breathing.2 Compared with A/C, ASV and SIMV+PSV all can make the patient,s Ppeak and Pmean degraded, accordingly they may lessen the non-physiological effect of elevated intrathoracic pressure caused by positive pressure ventilation in a extent, thus may avoid alveolar pressure hurt.3 Compared with A/C, ASV and SIMV+PSV all can make the patient,s P0.1 and RSB degraded, they all can lessen the breathing loading and the happening rate of patient-ventilator dyssynchrony.4 Compared with the routine mode for extubate of SIMV +PSV, The duration of invasion ventilation and the duration of non-invasion ventilation weren,t statistically significant , so ASV was also a reasonable mode for extubate.5 Compared with SIMV+PSV, the regulation rate during ASV was fewer, and the parameters which should be set up is less, so operating is more simple, easily to be mastered by clinician, thus the management of mechanical ventilation is more simple.6 During using the ASV mode, a few patients may appear the phenomenon of"larger VT, and lower RR", whether this can increase the rate of alveolus volume hurt or not by long-term using is unknown, it want to be researched further.