• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.260-267
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• 2019

In the present study, we aimed to demonstrate that MV2000-MT(SU:M2)^® (MV, MEK-ICS, Paju, Korea), a domestic ventilator, is not inferior in terms of usability, safety, and medical staff satisfaction as compared to Hamilton G5 (G5, Hamilton Medical AG, Rhäzuns, Switzerland). A total of 39 patients who applied MV (group M) or G5 (group H) were included in the study sample. Usability was evaluated by the following factors: the number of alarm errors, replacement requirement of breathing circuit, replacement requirement of a right-angle connector, and ease of ventilator weaning. For safety evaluation, the number of ventilator replacements due to malfunction of the ventilator was evaluated. Items for medical staff satisfaction survey were as follows: the number of MV and G5 uses, hardware, and software assessment. In the usability evaluation, the replacement requirement of the right-angle connector was lower in Group M than in Group H (mean ± standard deviation, Group M: 7.39 ± 6.72, Group H: 14.19 ± 10.24, p = 0.021); however, the evaluations of other parts were not significantly different between the two groups. The number of ventilator replacements due to a malfunction of the ventilator did not differ between two groups. The number of MV and G5 uses was 3.0 [3.0-4.0] and 10.0 [5.0-10.0] (median [interquartile range], p < 0.001). Overall, the mean medical staff satisfaction score of Hamilton G5 was higher than that of MV2000-MT(SU:M2)^®. The usability of MV is comparable to that of G5. However, medical staff satisfaction with Hamilton G5 was higher than that with MV2000-MT(SU:M2)^®, and this difference could be due to the difference in the number of uses. In order to improve the penetration rate of the domestic mechanical ventilator, it is necessary to find ways to increase familiarity of medical staff with domestic mechanical ventilators.

• Tuberculosis and Respiratory Diseases
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• v.44 no.6
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• pp.1326-1331
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• 1997

Background : Weaning is the process of switching a patient from mechanical ventilator to spontaneous breathing. A number of different weaning techniques can be employed. At recent study, conventional spontaneous breathing trial was superior to other techniques, such as intermittent mandatory ventilation(IMV) or pressure support ventilation(PSV). But adequate observation time of the spontaneous breathing trial was not determined. We reported the effectiveness of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotrachial tube. In this study, we tried to shorten the spontaneous breathing time from 60 minutes to 30 minutes. If weaning success was predicted after 30 minutes spontaneous breathing, extubation was done without reconnection with ventilator. Methodes : Subjects consisted of 42 mechanically ventilated patients from August 1994 to July 1995. The weaning trial was done when the patients recovered sufficiently from respiratory failure that originally required ventilatory assistance, the patients became alert and showed stable vital sign, and arterial $O_2$ tension was adequated($PaO_2$ > 55 mmHg) with less than 40% of inspired oxygen fraction. We conducted a careful physical examination when the patients was breathing spontaneously through the endobronchial tube for 30 minutes. We terminated the trial if a patients was any of following signs of distress; cyanosis, diaphoresis, tachypnea(above 30 breaths per minute), and extreme tachycardia. Patients who had none of this features during spontaneous breathing for 30 minutes were extubated promptly. Result : 17 weaning trials of 15 patients were done in 42 mechanically ventilated patients. Successful weaning and extubation was possible in 14 trials of total 17 trials. In this 14 patients, 8 patients were extubated after 30 minutes spontaneous breathing, 3 patients were extubated after 60 minutes spontaneous breathing, and 3 patients needed over 3 hours for extubation from weaning. We found similar overall success rate compared with weaning following a 60 minutes spontaneous breathing trial. Conclusion : From the result of present study, we believe that weaning and extubation from mechanical ventilation following a 30 minutes spontaneous breathing with $O_2$ supply through the endotracheal tube is a simple and effective method.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.500-511
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• 1999

Background: Noninvasive positive pressure ventilation (NPPV) using facial or nasal mask have been widely used for several years in stable patients with chronic neuromuscular disease or central alveolar hypoventilation, and recently have been tried in patients with acute respiratory failure. In a few studies, NPPV was also used to rescue the patients with post-extubation respiratory failure. However, yet it has not been adopted as a weaning method in patients on long-term mechanical ventilation. So we performed this prospective clinical study to evaluate the usefulness of NPPV as a weaning method after removing endotracheal tube intentionally in patients on long-term mechanical ventilation. Method: Twelve patients who had been on invasive mechanical ventilation over 10 days were enrolled and 14 trials of NPPV were done. All had failed at least one weaning trial and showed ventilator dependence(pressure support requirement between 8-15cm $H_2O$, and PEEP requirement between 5-10cm $H_2O$), so tracheostomy was being considered. After removing the endotracheal tube, NPPV was applied using facial mask. Respiratory rate, arterial blood gas, pressure support level, and PEEP level were monitored just before intended extubation, at 30 minutes, 1 to 6, 6 to 12, 12 to 24 hours, 2nd day, and 3rd day following initiation of NPPV, and just before weaning from NPPV. The successful weaning was defined as spontaneous breathing off the ventilator for 48 hours or longer without respiratory distress. Results: The weaning through NPPV after intended extubation was successful in 7(50%) of 14 trials, and tracheostomy could be avoided in them. There were no differences in age, sex, APACHE III score, duration of invasive mechanical ventilation, baseline respiratory rate, $PaCO_2$ $PaO_2/FiO_2$, and ventilatory requirement(PS and PEEP) between the success and failure groups. In the success group, respiratory rate, pH, $PaCO_2$, and $PaO_2/FiO_2$ were not different between invasive MV and NPPV period. But in the failure group, pH decreased after 30 minutes of NPPV initiation compared with that of invasive MV($7.40\pm0.08$ vs. $7.34\pm0.06$, p<0.05). The causes of failure were worsening of ABG(n=3), retained tracheal secretion(n=2), mask intolerance(n=1), and flail chest(n=1). Conclusion: NPPV may be worth trying as a bridge method in weaning patients on long-term invasive mechanical ventilation.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.43-49
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• 2004

Background: Acute thoracic aortic dissections involving the aortic arch differ in diagnosis, surgical procedures, and operative results compared to those that do not involve the aortic arch. In general cerebral perfusion under deep hypothermic circulatory arrest (HCA) is performed during the repair of the aortic arch dissection. Here, we report our surgical results of the aortic arch dissection repair using retrograde cerebral perfusion (RCP) and its safety. Material and Method: Between January 1996 and June 2002, 22 consecutive patients with aortic arch dissection underwent aortic arch repair. In 20 of them RCP was performed under HCA. RCP was done through superior vena cava in 19 patients and by systemic retrograde venous perfusion in 1, in whom it was difficult to reach the SVC. When the patient's rectal temperature reached 16 to 18$^{\circ}C$, systemic circulation was arrested, and the amount of RCP amount was 481.1 $\pm$292.9 $m\ell$/min with perfusion pressure of 20∼30 mmHg. Result: There were two in-hospital deaths (4.5%) and one late death (9.1%). Mean circulatory arrest time (RCP time) was 54.0$\pm$ 13.4 minutes (range, 7 to 145 minutes). RCP time has no correlation with the appearance of consciousness, recovery of orientation, or ventilator weaning time (p=0.35, 0.86, and 0.92, respectively). Ventilator weaning was faster in patients with earlier recovery of consciousness and orientation (r=0.850, r=926; p=0.000, respectively). RCP of more than 70 minutes did not affect the appearance of consciousness, recovery of orientation, ventilator weaning time, exercise time, or hospital stay (p=0.42, 0.57, 0.60, 0.83, and 0.51, respectively). Conclusion: Retrograde cerebral perfusion time under hypothermic circulatory arrest during repair of aortic arch dissection may not affect recovery of orientation, ventilator weaning time, neurologic complications, and postoperative recovery.

• Journal of Korean Neurosurgical Society
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• v.64 no.5
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• pp.791-798
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• 2021

Objective : The period of mechanical ventilator (MV)-dependent respiratory failure after cervical spinal cord injury (CSCI) varies from patient to patient. This study aimed to identify predictors of MV at hospital discharge (MVDC) due to prolonged respiratory failure among patients with MV after CSCI. Methods : Two hundred forty-three patients with CSCI were admitted to our institution between May 2006 and April 2018. Their medical records and radiographic data were retrospectively reviewed. Level and completeness of injury were defined according to the American Spinal Injury Association (ASIA) standards. Respiratory failure was defined as the requirement for definitive airway and assistance of MV. We also evaluated magnetic resonance imaging characteristics of the cervical spine. These characteristics included : maximum canal compromise (MCC); intramedullary hematoma or cord transection; and integrity of the disco-ligamentous complex for assessment of the Subaxial Cervical Spine Injury Classification (SLIC) scoring. The inclusion criteria were patients with CSCI who underwent decompression surgery within 48 hours after trauma with respiratory failure during hospital stay. Patients with Glasgow coma scale 12 or lower, major fatal trauma of vital organs, or stroke caused by vertebral artery injury were excluded from the study. Results : Out of 243 patients with CSCI, 30 required MV during their hospital stay, and 27 met the inclusion criteria. Among them, 48.1% (13/27) of patients had MVDC with greater than 30 days MV or death caused by aspiration pneumonia. In total, 51.9% (14/27) of patients could be weaned from MV during 30 days or less of hospital stay (MV days : MVDC 38.23±20.79 vs. MV weaning, 13.57±8.40; p<0.001). Vital signs at hospital arrival, smoking, the American Society of Anesthesiologists classification, Associated injury with Injury Severity Score, SLIC score, and length of cord edema did not differ between the MVDC and MV weaning groups. The ASIA impairment scale, level of injury within C3 to C6, and MCC significantly affected MVDC. The MCC significantly correlated with MVDC, and the optimal cutoff value was 51.40%, with 76.9% sensitivity and 78.6% specificity. In multivariate logistic regression analysis, MCC >51.4% was a significant risk factor for MVDC (odds ratio, 7.574; p=0.039). Conclusion : As a method of predicting which patients would be able to undergo weaning from MV early, the MCC is a valid factor. If the MCC exceeds 51.4%, prognosis of respiratory function becomes poor and the probability of MVDC is increased.

• Journal of Trauma and Injury
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• v.26 no.4
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• pp.291-296
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• 2013

Purpose: Prolonged ventilation leads to a higher incidence of ventilator-associated pneumonia (VAP), resulting in weaning failure and increased medical costs. The aim of this study was to analyze clinical results and prognostic factors of VAP in patients with blunt chest trauma. Methods: From 2007 to 2011, one hundred patients undergoing mechanical ventilation for more than 48 hours were divided into two groups: a VAP-negative group, (32 patients, mean age; 53 years, M:F=25:7) and a VAP- positive group, (68 patients, mean age; 60 years, M:F=56:12). VAP was diagnosed using clinical symptoms, radiologic findings and microorganisms. The injury severity score (ISS), shock, combined injuries, computerized tomographic pulmonary findings, transfusion, chronic obstructive lung disease (COPD), ventilation time, stay in intensive care unit (ICU) and hospital stays, complications such as sepsis or disseminated intravascular coagulation (DIC) and microorganisms were analyzed. Chi square, t-test, Mann-Whitney U test and logistic regression analysies were used with SPSS 18 software. Results: Age, sex, ISS, shock and combined injuries showed no differences between the VAP - negative group and - positive group (p>0.05), but ventilation time, ICU and hospital stays, blood transfusion and complications such as sepsis or DIC showed significant differencies (p<0.05). Four patients(13%) showed no clinical symptoms eventhough blood cultures were positive. Regardless of VAP, mortality-related factors were shock (p=0.036), transfusion (p=0.042), COPD (p=0.029), mechanical ventilation time (p=0.011), ICU stay (p=0.032), and sepsis (p=0.000). Microorgnisms were MRSA(43%), pseudomonas(24%), acinetobacter(16%), streptococcus(9%), klebsiela(4%), staphillococus aureus(4%). However there was no difference in mortality between the two groups. Conclusion: VAP itself was not related with mortality. Consideration of mortality-related factors for VAP and its aggressive treatment play important roles in improving patient outcomes.

• Journal of Chest Surgery
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• v.29 no.9
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• pp.1045-1049
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• 1996

Post-intubation tracheoesophageal fistula is rare, and its management causes a serious problems to surgeons. We have experienced 4 cases in 3 patients. Simple ditcision and closure of the fistulas were done by trans-cervical approach after weaning of ventilator. The tracheal defect was closed by simple suture, and the esophageal defect was closed in two layers before a viable muscle flap was interposed between the two suture lines in order to prevent recurrence. There was one delayed tracheal stenosls and one recurrent fistula, and these complications were also managed success ully.

• Tuberculosis and Respiratory Diseases
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• v.42 no.3
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• pp.361-369
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• 1995

Background: A number of different weaning techniques can be employed such as spontaneous breathing trial, Intermittent mandatory ventilation(IMV) or Pressure support ventilation(PSV). However, the conclusive data indicating the superiority of one technique over another have not been published. Usually, a conventional spontaneous breathing trial is undertaken by supplying humidified $O_2$ through T-shaped adaptor connected to endotracheal tube or tracheostomy tube. In Korea, T-tube trial is not popular because the high-flow oxygen system is not always available. Also, the timing of extubation is not conclusive and depends on clinical experiences. It is known that to withdraw the endotracheal tube after weaning is far better than to go through any period. The tube produces varying degrees of resistance depending on its internal diameter and the flow rates encountered. The purpose of present study is to evaluate the effectiveness of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube. Methods: We analyzed the result of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube in 18 subjects from June, 1993 to June, 1994. They consisted of 9 males and 9 females. The duration of mechanical ventilation was from 38 hours to 341 hours(mean: $105.9{\pm}83.4$ hours). In all cases, the cause of ventilator dependency should be identified and precipitating factors should be corrected. The weaning trial was done when the patient became alert and arterial $O_2$ tension was adequate($PaO_2$ > 55mmHg) with an inspired oxygen fraction of 40%. We conducted a careful physical examination when the patient was breathing spontaneously through the endotracheal tube. Failure of weaning trial was signaled by cyanosis, sweating, paradoxical respiration, intercostal recession. Weaning failure was defined as the need for mechanical ventilation within 48 hours. Results: In 19 weaning trials of 18 patients, successful weaning and extubation was possible in 16/19(84.2 %). During the trial of spontaneous breathing for 60 minutes through the endotracheal tube, the patients who could wean developed slight increase in respiratory rates but significant changes of arterial blood gas values were not noted. But, the patients who failed weaning trial showed the marked increase in respiratory rates without significant changes of arterial blood gas values. Conclusion: The result of present study indicates that weaning from mechanical ventilation following a 60 minutes spontaneous breathing with $O_2$ supply through the endotracheal tube is a simple and effective method. Extubation can be done at the same time of successful weaning except for endobronchial toilet or airway protection.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.380-387
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• 1998

Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

• Child Health Nursing Research
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• v.20 no.3
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• pp.225-235
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• 2014

Purpose: The purpose of this study was to analysis the effects of nasal Continuous Postive Airway Pressure (nCPAP) for preterm infants using systematic review and meta-analysis. Methods: Thirteen peer-reviewed journals including preterm infants and apnea and nCPAP published between 1973 and 2013 were included. Effect size and statistics of homogeneity were done using STATA 10.0. Results: The design for 9 studies was Randomized Control Trial. In most of studies the pressure of nCPAP was set to 4-6 cm$H_2O$. The effect size of 5 studies for the effect on apnea rate using nCPAP compared to nasal Intermittent Positive Pressure Ventilator (nIPPV) showed that the Standardized Mean Difference (SMD) was -0.11 and was not significantly different (Z=0.41, p=.680). But the difference in nCPAP for nasal Synchronizes Intermittent Positive Pressure Ventilator (nSIPPV) (subgroup) was significant (SMD=-.44). The effect size of 7 studies on effect for ventilator weaning of using nCPAP compared to nIPPV showed the Risk Ratio (RR) as 1.60 and was not significantly different (Z=1.12, p=.268). But the difference between nCPAP and nSIPPV (subgroup) was significant (RR=3.94). Conclusion: The results indicate a need for an advanced care system and suggest continuous studies of apnea in preterm infants.