Pendelluft volume during double-triggered asynchronous breaths under pressure support ventilation: a prospective physiological study / 中华危重病急救医学

Objective:To investigate the relationship between double-triggering and abnormal movement of air in the lungs (pendelluft phenomenon) under pressure support ventilation (PSV).Methods:A prospective observational study was conducted, postoperative patients admitted to department of critical care medicine of Beijing Tiantan Hospital, Capital Medical University from April 1, 2019 to August 31, 2020 and received invasive mechanical ventilation with PSV mode were enrolled. Electrical impedance tomography (EIT) monitoring was performed. Airway pressure-time, flow-time, global and regional impedance-time curves were synchronously collected and analyzed offline. The volume of abnormal movement of air in the lungs at the beginning of inspiration was measured and defined as pendelluft volume. Double-triggered breaths were identified by trained researchers. Pendelluft volume during double-triggering was measured including the first triggered breath, the double-triggered breath, and the breath immediately following the double-triggered breath. Pendelluft volume was also measured for normal breath during the study. According to the frequency of double-triggering, patients were divided into severe (≥1 time/min) and non-severe double-triggering group. Pendelluft volume, parameters of respiratory mechanics, and clinical outcomes between the two groups were compared.Results:In 40 enrolled patients, a total of 9 711 breaths [(243±63) breaths/patient] were collected and analyzed, among which 222 breaths (2.3%) were identified as double-triggering. The Kappa of interobserver reliability to detect double-triggering was 0.964 [95% confidence interval (95% CI) was 0.946-0.982]. In 222 double-triggered breaths, pendelluft volume could not be measured in 7 breaths (3.2%), but the pendelluft phenomenon did exist as shown by opposite regional impedance change at the beginning of double-triggered inspiration. Finally, pendelluft volume was measured in 215 double-triggered breaths. Meanwhile, 400 normal breaths (10 normal breaths randomly selected for each patient) were identified as control. Compared with normal breath, pendelluft volume significantly increased in the first breath, the double-triggered breath, and the following normal breath [mL: 3.0 (1.4, 6.4), 8.3 (3.6, 13.2), 4.3 (1.9, 9.1) vs. 1.4 (0.7, 2.8), all P < 0.05]. Patients in severe double-triggering, pendelluft volume of normal breath and double-triggered breath were significantly higher than those in non-severe double-triggering group [mL: 1.8 (0.9, 3.2) vs. 1.1 (0.5, 2.1), P < 0.001; 8.5 (3.9, 13.4) vs. 2.0 (0.6, 9.1), P = 0.008]. Patients in severe double-triggering group had significantly higher respiratory rate than that in the non-severe double-triggering group (breaths/min: 20.9±3.5 vs. 15.2±3.7, P < 0.001). There were no significant differences in other respiratory mechanics parameters and main clinical outcomes between the two groups. Conclusions:During PSV, the abnormal movement of air in the lungs (pendelluft phenomenon) was more likely to occur in double-triggering especially in double-triggered breath. The more frequent the double-triggering occurred, the more serious the pendelluft phenomenon was. A higher pendelluft volume of normal breath and a higher respiratory rate were related to severity of double-triggering.

Effect of neurally adjusted ventilatory assist on trigger of mechanical ventilation in acute exacerbation of chronic obstructive pulmonary disease patients with intrinsic positive end-expiratory pressure / 中华内科杂志

Objective To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients with intrinsic positive end-expiratory pressure (PEEP) during mechanical ventilation. Methods AECOPD patients with intrinsic PEEP (PEEPi) greater than or equal to 3 cmH2O (1 cmH2O=0.098 kPa) were enrolled during invasive mechanical ventilation. Subjects were ventilated with low, medium and high pressure under either NAVA or PSV mode. Servo Tracker software continuously recorded the waveform of ventilator and respiratory mechanics indexes (including respiratory frequency, inspiratory tidal volume (Vti), minute ventilation volume (VE), peak airway pressure (PIP), inspiratory time), and calculated trigger and expiratory conversion delay time, work of trigger and total work of breath. Results A total of 14 AECOPD patients were enrolled with the average PEEPi (4.3±1.3) cmH2O. PSV inspiratory trigger delay time was positively correlated with PEEPi (r=0.913, P<0.05). Compared with PSV, NAVA significantly decreased trigger delay time in low, medium and high pressure level groups [(48±17) ms vs. (167±86) ms, (63±65) ms vs. (247±240) ms, (63±49) ms vs. (342±192) ms,respectively all P<0.05]. Similar results were shown as to work of trigger [(0.92±0.36) μV?s vs. (1.22±0.70) μV?s, (1.08±0.51) μV?s vs. (1.62 ± 1.25) μV?s, (1.20 ± 0.96) μV?s vs. (2.29 ± 1.02) μV?s, all P<0.05]. Trigger delay time increased according to the increase of pressure level in PSV mode.Conclusion The presence of PEEPi in AECOPD patients leads to obvious trigger delay under PSV mode, which is positively correlated with PEEPi level. NAVA significantly reduces trigger delay time and work of trigger compared with PSV mode.

Comparison of the effect of CPAP+PPS mode and CPAP+ASB mode in weaning on acute exacerbation of chronic obstructive pulmonary disease patients / 中华危重病急救医学

Objective To investigate the effect of different appropriate modes of weaning from mechanical ventilation (MV) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods Patients with AECOPD and mechanically ventilated by orotracheal intubation, suitable for continuous positive airway pressure+proportional pressure support (CPAP+PPS) and CPAP+assisted spontaneous breath (ASB) ventilation mode for weaning from MV, admitted to intensive care unit (ICU) of Tianjin Third Central Hospital form January 1st, 2016 to December 31st, 2017 were enrolled. When the patients recovered to spontaneous respiration and down regulation of ventilator support frequency to 10 bpm, they were taken ventilator weaning in CPAP+PPS and CPAP+ASB mode according to the random number table method, respectively. Basic characteristics, ventilator parameters, the incidence of high man-machine confrontation (man-machine confrontation index > 10%) and clinical outcomes (ventilator weaning time, which was defined as the time from randomization to successful weaning from MV, ventilator weaning failure times, the duration of MV, the length of ICU stay and the length of hospital stay) were compared between the two groups. Results Eighty-seven AECOPD patients were selected, 44 in CPAP+ASB group and 43 in CPAP+PPS group. There was no significant difference in gender, age, acute physiology and chronic health evaluation Ⅱ(APACHEⅡ), sequential organ failure score (SOFA), Glasgow coma score (GCS), Charsen index and the highest arterial blood carbon dioxide partial pressure (PaCO2), the lowest arterial oxygen partial pressure (PaO2) and tidal volume (VT) at the time of onset between the two groups. Compared with CPAP+ASB group, incidence of high man-machine confrontation was significantly decreased in CPAP+PPS group [9.30% (4/43) vs. 27.27% (12/44), P =0.027], and the airway occlusion pressure (P0.1) was significantly decreased [cmH2O (1 cmH2O = 0.098 kPa): 2.21±0.83 vs. 2.63±0.94, P = 0.032], and the failure rate of the first spontaneous breathing trial (SBT) was significantly decreased [6.98% (3/43) vs. 22.73% (10/44), P = 0.039], ventilator weaning time, the length of ICU stay and the length of hospital stay were significantly shortened [ventilator weaning time (hours): 12.73±14.23 vs. 50.64±38.11, the length of ICU stay (hours): 254.53±108.06 vs. 344.93±124.95, the length of hospital stay (days): 18.53±7.59 vs. 26.64±11.22, all P < 0.05]. However, there was no significant difference in PaCO2, duration of MV, ICU mortality and hospital mortality between the two groups. Conclusion Compared with CPAP+ASB ventilation mode, CPAP+PPS ventilation mode can reduce respiratory muscle load, promote respiratory function recovery, and reduce the occurrence of man-machine confrontation, which is beneficial to AECOPD patients taking ventilator weaning, and can significantly shorten the ventilator weaning time of patients and further shorten the hospitalization time.

Short-term application of noisy pressure support ventilation in patients of AECOPD with respiratory failure / 天津医药

Objective To investigate the effects of noisy pressure support ventilation (Noisy PSV) in patients of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with respiratory failure, and to provide basic support for the new weaning mode for AECOPD. Methods A single-center, prospective, randomized, crossover clinical research was conducted. A total of forty-six AECOPD combined with respiratory failure patients who mechanically ventilated more than 24 hours in intensive care unit (ICU) of Tianjin Haihe Hospital from November 2014 to October 2015 were enrolled in this study. When the respiratory failure improved through conventional treatment, patients were mechanically ventilated with conventional PSV and Noisy PSV for two hours respectively in random sequence during spontaneous breathing recovery phase. The pressure support (PS) level was titrated to reach tidal volumes (Vt) about 8 mL/kg in both modes. The level of positive end-expiratory pressure (PEEP) and fraction of inspired oxygen were kept unchanged in both modes. The coefficient of variation of PS during Noisy PSV was set at 30%. Data of gas exchange, hemodynamics, lung functional parameters, breathing patterns and patient-ventilator synchrony were analyzed. Results All of the patients were well tolerated with the two modes, and no adverse reactions were found. The changes of gas exchange, hemodynamics, respiratory mechanics in PSV and Noisy PSV showed a clinical acceptable range. The variability of Vt was significantly increased in Noisy PSV mode than that in conventional PSV mode. While the number of asynchrony events was decreased in Noisy PSV mode than that in conventional PSV mode. Conclusion The Noisy PSV is safe and feasible for patients of AECOPD with respiratory failure, which may be a new weaning mode for AECOPD.

The safety and efficiency of non-invasive pressure support ventilation through a non-invasive ventilation-helmet in children after surgical repair of congenital heart disease / 中国小儿急救医学

Objective To analyze the safety and effect of non-invasive pressure support ventilation in 32 patients by using a helmet and to give the appropriate way of patients who need non-invasive ventilation ( NIV) support after congenital heart disease surgery. Methods Patients over one year old after congential heart disease surgery were admitted in our Department of Cardiovascular Thoracic Surgery from July 2015 to December 2015. Patients who get clinically improved within one hour were divided into the early improved group( Group-E) ,otherwise they were classified to non-early improved group( Group-NE) . The general infor-mation,diagnosis, indication of NIV, ICU and hospital stay, complications, and mortality were collected. Results Thirty-two patients were engaged in this study,including 18 patients(56. 25%) in Group-E and 14 patients(43. 75%) in Group-NE. Patients who got improved in the first hour might have a higher incidence of avoiding reintubation[83. 33%(15/18) vs. 42. 86%(6/14),P=0. 02]. The heart rate,respiratory rate, pH,PaO2/FiO2 and lactate were improved in Group-E compared with Group-NE after the first hour by using helmet. At the end of NIV,the oxygenation showed no difference but the PaCO2 was lower in Group-E. In Group-E,the values showed a trend of improvement,while the values in Group-NE showed not only no statis-tical significance in different time points but also seemed to have a tendency of hypercapnia and reduced com-fort behavior scale in the end of NIV. There were 6 cases in Group-E and 10 cases in Group-NE developed ventilation associated pneumonia with the incidence of 33. 33%(6/18) and 71. 43%(10/14),respectively, which was significant difference (χ2 =4. 571,P =0. 03). The total duration of mechanical ventilation of Group-E was shorter than that of Group-NE [ ( 136. 72 ± 151. 49 ) h vs. ( 252. 79 ± 155. 33 ) h, P <0. 05 ] . Conclusion NIV through a helmet in children could be well tolerated and avoid re-intubation. Patients who get improved earlier may have more clinical advantages,such as less time of mechanical ventilation and lower incidence of postoperative complications. Early improvement can be considered as a valuable indicator wheth-er the patient needs to use NIV continuously.

Efficacy of pressure support ventilation in infants undergoing laparoscopic hernia repair under sevoflurane anesthesia / 中华麻醉学杂志

Objective To evaluate the efficacy of pressure support ventilation ( PSV ) in the infants undergoing laparoscopic hernia repair under sevoflurane anesthesia. Methods Thirty ASA physical statusⅠpediatric children, aged 9 months-1 yr, weighing 8.0-11.5 kg, undergoing elective laparoscopic hernia repair, were randomly assigned into 3 groups ( n=10 each) using a random number table: pressure control ventilation ( PCV) used for muscle relaxants in combination with low?concentration sevoflurane group ( group PCV1 ) , PCV used for high?concentration sevoflurane group ( group PCV2 ) , and PSV used for low?concentration sevoflurane group ( group PSV) . Anesthesia was induced with inhalation of 4%-6%sevoflurane and iv fentanyl 2 μg∕kg and succinylcholine 1.5 mg∕kg. The pediatric children were endotracheally intubated and mechanically ventilated. In PCV1 and PCV2 groups, PCV was used during operation. In group PSV, PCV was used first after intubation, and then PSV was applied after spontaneous breathing recovered. Anesthesia was maintained as follows: in group PCV1 , the end?tidal concentration of sevoflurane was maintained at 2.5% - 3.0%, and cisatracurium besylate 0.1 mg∕kg was injected intermittently as required; in group PCV1 , the end?tidal concentration of sevoflurane was maintained at 3.5%-4.0%; in group PSV, the end?tidal concentration of sevoflurane was maintained at 2.5%-3.0%, and succinylcholine 1.0 mg∕kg was injected intravenously before pneumoperitoneum. Narcotrend index value was maintained at 50-60 in PCV1 and PSV groups, or at 37-45 in PCV2 group. Heart rate ( HR) and mean arterial pressure (MAP) were recorded before induction of anesthesia (baseline), at the beginning of pneumoperitoneum, at 5 and 10 min of pneumoperitoneum, at the end of pneumoperitoneum, at the end of operation and immediately after extubation. The time interval from the end of surgery to extubation was recorded. Results Pulse oxygen saturation was 100% during anesthesia, and>95% during recovery from anesthesia in the three groups. Compared with the baseline value, HR was significantly faster, and MAP was increased during extubation in PCV1 and PCV2 groups, and no significant change was found in HR and MAP at each time point in group PSV. The time interval from the end of surgery to extubation was 30.3± 5.4, 18.4±4.3 and (4.1±1.2) min in PCV1, PCV2 and PSV groups, respectively. Compared with PCV1 and PCV2 groups, the time interval from the end of surgery to extubation was significantly shortened in group PSV. Conclusion When PSV is applied in the infants undergoing laparoscopic hernia repair under sevoflurane anesthesia, it can provide adequate ventilation, recovery from anesthesia is rapid, and no cardiovascular responses occur during extubation.

Effects of neurally adjusted ventilatory assist on inflammatory reaction and weaning in patients with AECOPD / 中华急诊医学杂志

Objective To observe the correlation between neutrally adjusted ventilatory assist (NAVA) mode and improvement of inflammation and oxidative stress in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD),and as well as to investigate the effects of NAVA mode versus pressure support ventilation (PSV) mode on improving the success rate of weaning advantages.Methods A total of 40 patients with AECOPD-Ⅲ supported by mechanical ventilation treatment admitted from November 2012 to January 2014 into intensive care unit (ICU) were enrolled for prospective study.The patients were randomly divided into PSV mode (n =20) and NAVA mode (n =20) according to gender,age,APACHE Ⅱ score,medical history,PaCO2 of five factors and adopting the principle of minimum distribution of the imbalance index.The comparisons of the successful rate of weaning,48 h re-intubation rate and length of ICU stay were made between two groups.The level of C-reactive protein (CRP),serum amyloid A (SAA),human cartilage glycoprotein 39 (YKL-40) in serum were measured by enzyme-linked immunosorbent assay (ELSIA) on the 1st day,3rd day,5th day and 7th day after initiation of mechanical ventilation,and results of these laboratory tests in patients were compared with those in healthy subjects of control group.And simultaneously,the broncho-alveolar lavage fluid (BALF) was collected with Gibot method by employment of optic fiber bronchoscope on the given days for detection of YKL-40,and levels of YKL-40 were compared between NAVA mode and PSV mode.Enumeration data were analyzed with x2 test,measurement data were analyzed with t test or repeated measures analysis of variance,and P ＜ 0.05 was considered to be significant.Results (1) There were no significant differences in leukocyte count and neutrophils percentage between NAVA mode and PSV mode (P ＞ 0.05).The magnitudes of decrease in concentrations of blood CRP and SAA in NAVA mode were significantly greater than those in PSV mode (P ＜ 0.01),but there was no significant difference in blood YKL-40 between NAVA mode and PSV mode (P ＞ 0.05).The magnitude of reduction in concentration of BALF YKL-40 in NAVA mode was significantly greater than that in PSV mode (P ＜0.01).(2) There was on significant difference in rate of final weaning between NAVA mode and PSV mode,but the rate of direct weaning was higher in NAVA mode than that in PSV mode (P =0.046),and the 48 h re-intubation rate was lower in NAVA mode than that in PSV mode (P =0.032).The length of ICU stay was shorter in NAVA mode than that in PSV mode (P =0.031).The peak of EAdi (electric activated diaphragma trigger) in 8 patients failing in direct weaning before first attempt was significantly higher than that in other patients with successful weaning patients (P =0.002).Conclusions NAVA mode can attenuate inflammation and oxidative stress in patients with AECOPD,and ultimately improve the rate of direct weaning and shorten the length of ICU stay.Further research is necessary to confirm the capability of NAVA mode for improving the ultimate rate of weaning in AECOPD patients.

The effects of different ventilator modes on cerebral tissue oxygen saturation in patients with bidirectional superior cavopulmonary connection.

Aims and Objectives: We used near‑infrared spectroscopy to document changes in cerebral tissue oxygen saturation (SctO2) in response to ventilation mode alterations after bidirectional Glenn (BDG; superior cavopulmonary connection) procedure. We also determined whether spontaneous ventilation have a beneficial effect on hemodynamic status, lactate and SctO2 when compared with other ventilation modes. Materials and Methods: 20 consecutive patients undergoing BDG were included. We measured SctO2 during three ventilator modes (intermittent positive‑pressure ventilation [IPPV]; synchronized intermittent mandatory ventilation [SIMV]; and continuous positive airway pressure + pressure support ventilation [CPAP + PSV]). We, also, measured mean airway pressure (AWP), arterial blood gases, lactate and systolic arterial pressures (SAP). Results: There was no change in SctO2 in IPPV and SIMV modes; the SctO2 measured during CPAP + PSV and after extubation increased significantly (60.5 ± 11, 61 ± 10, 65 ± 10, 66 ± 11 respectively) (P < 0.05). The differences in the SAP measured during IPPV and SIMV modes was insignificant; the SAP increased significantly during CPAP + PSV mode and after extubation compared with IPPV and SIMV (109 ± 11, 110 ± 12, 95 ± 17, 99 ± 13 mmHg, respectively) (P < 0.05). Mean AWP did not change during IPPV and SIMV modes, mean AWP decreased significantly during CPAP + PSV mode (14 ± 4, 14 ± 3, 10 ± 1 mmHg, respectively) (P < 0.01). Conclusions: The SctO2 was higher during CPAP + PSV ventilation and after extubation compared to IPPV and SIMV modes of ventilation. The mean AWP was lower during CPAP + PSV ventilation compared to IPPV and SIMV modes of ventilation.

Interação paciente ventilador nas diferentes fases do ciclo ventilatório em ventilação por pressão de suporte / Patient-ventilator interaction on different phases of mechanical breath in pressure support ventilation

Introdução: O principal objetivo da ventilação mecânica é a diminuição do trabalho respiratório. Para que isto ocorra, o ciclo mecânico deveria coincidir com o tempo inspiratório neural do paciente. A assincronia paciente ventilador ocorre por fatores relacionados ao paciente e aos parâmetros ventilatórios e podem prolongar o tempo de suporte mecânico e permanência em unidades de terapia intensiva. Objetivos: Revisar a assincronia nas diferentes fases do ciclo respiratório, sua avaliação através dos gráficos e as intervenções capazes de melhorar a interação paciente ventilador em ventilação por pressão de suporte. Resultados/ Discussão: Através de busca em base de dados científicos, foram incluídos 26 artigos que abordavam o tema proposto. Os diferentes tipos de assincronia podem ser observados através de esforços ineficientes, atrasos no disparo, disparos automáticos, disparos duplos, presença de PEEP intrínseca, términos prematuro ou prolongado da inspiração e curvas diferentes do padrão usual. Conclusão: A correta identificação e ajustes conforme a demanda do paciente são pontos importantes na interação paciente ventilador e podem contribuir para a melhora do prognóstico destes pacientes.(AU)

Introduction: The main reason of mechanical ventilation is the decrease the work of breathing. To achieve it, the mechanical breath should coincide with the neural inspiratory time. Patient-ventilator asynchrony may be secondary for the facts related to the patient´s condition or ventilatory settings and may prolong support and UTI stay. Objectives: Review asynchrony in different phases of mechanical breath, the evaluation through ventilator waveforms and the proper settings to improve patient-ventilator interaction in pressure support ventilation. Results/ Discussion: Through research on scientific basis, 26 studies that match the theme were included. Asynchrony may be seen as inefficient efforts, trigger delay, auto-triggering, double triggering, presence of auto-PEEP, premature termination, delayed termination or unusual waveforms. Conclusion: Proper identification and adjustments that coincides with patient´s demand are critical points in patient ventilator interaction and may contribute to improve their prognosis.(AU)

Ventilation administration during fiberoptic bronchoscopy in neonates / 中国小儿急救医学

Objective To assess ventilation administration during fiberoptic bronchoscopy (FB) in neonates. Methods Twenty-three neonates divided into two group (A group 12 neonates, B group 11 neonates) received FB. All were given pressure support ventilation (PSV)by a Y-like facility which connected to fiberoptic bronchoscope suction hole. In A group,after the tip of fiberoptic bronchoscope arrived at the carina, PSV was administrated. In B group, PSV was administrated in the entire process during FB, SpO2 and electrocardio were monitoring. Artery blood samples for blood gas analysis were obtained at four stages of just before FB,with the tip of the bronchoscope at the supralarynx,just before withdrawing bronchoscope out off trachea and within 20-30 minutes after FB. The arterial blood oxygen tension (PaO2), arterial blood carbon dioxide tension (PaCO2) and SpO2 just before FB served as baseline. The same indexes of other three stages were compared with the baseline. Results All 23 neonates were studied completely. When the tip of fiberoptic bronchoscope advanced from nostril to the supralarynx, SpO2, PaO2 and PaCO2 in two groups were similar to the baseline. In A group, when the tip below the glottis, cyanosis occurred, and SpO2 decreased significantly ( P＜0. 01 ) in 11 cases (92%) by 25% ; When tip at the carina, after PSV, cyanosis disappeared, and SpO2 returned to the baseline level, PaO2 keep on the baseline just before withdrawing the bronchoscope out of the trachea. SpO2 ,PaO2 in all B group neonates keep on the baseline during FB. After the tip below the glottis,PaCO2 in all neonates of the two groups increased significantly ( P＜0. 01 ), but returned to baseline within 20-30 minutes after FB. Conclusion FB can cause significant hypoxemia and hypercapnia in neonates. PSV through fiberoptic bronchoscope can be considered a safe and beneficial ventilation technique for maintaining oxygenation during FB.

Effects of respiratory mechanics in weaning patients with chronic obstructive pulmonary disease during proportional assist ventilation / 中国医师进修杂志

Objective To evaluate the effects of proportional assist ventilation (PAV) and pressure support ventilation (PSV) on ventilate parameters of patients with chronic obstructive pulmonary disease (COPD) combined with respiratory failure.Methods Fifteen intubated stable patients recovering from acute exacerbation of COPD combined with respiratory failure were randomized to receive PAV or PSV support 60 min and then crossed over to alternative mode.Respiratory mechanics including respiratory systemelastic resistance and airway resistance were monitored by least square fitting (LSF) methed.During PAV support.the ratio of volume assist (VA) and flow assist (FA) level wag 80%.The ventilate parameters and arterialblood gas at different ventilate condition was observed.Results Compared with low level PSV (PS 10 cm H2O,1 cm H2O=0.098 kPa,PS10),tidal volume in high level PSV (PS 15 cm H2O,PS15) and PAV was significantly increased [(443±12)ml vs(532±34)ml,(464±23)ml,P<0.05].There was no difference in respiratory rate and peak inspiratory pressure between PAV and PS10.Airway occlusion pressure and time product of triggering was d()reased from (5.70±0.25)cm H2O to (4.53±0.25)cm H2O and (0.42±0.04) cm H2O to (0.32±0.03)cm H2O(P<0.05),PaO2/FiO2 ratio and PaCO2 was also significantly improved after PAV supported compared with PS10,and similar with PS15.The rapid shallow breath index at PAV was similar with PS10.Condusion As a positive feedback system,PAV seems more efficacious than low level of PSV in decreasing the work of breathing during the inspiratory phase,resulting in fewer patient-ventilator asynchronism,and it may be beneficial for weaning.

Comparação entre três métodos de obtenção do índice de respiração rápida e superficial em pacientes submetidos ao desmame da ventilação mecânica / Comparison among three methods to measure the rapid shallow breathing index in patients submitted to weaning from mechanical ventilation

JUSTIFICATIVA E OBJETIVOS: Esta pesquisa justifica-se na necessidade de maior conhecimento a respeito das técnicas de desmame ventilatório utilizadas em pacientes sob ventilação mecânica prolongada. O objetivo deste estudo foi comparar a obtenção do índice de respiração rápida e superficial (IRRS) nas modalidades PSV de 10 cmH2O e PEEP de 5 cmH2O (PSV10); CPAP de 5 cmH2O (CPAP5) e em ventilação espontânea (ESP), correlacionando com sucesso ou insucesso na retirada da ventilação mecânica (VM). MÉTODO: Estudo prospectivo incluindo 54 pacientes em VM há mais de 48 horas, submetidos ao IRRS em três modos ventilatórios: PSV10, CPAP5 e ESP nos momentos pré e pós-nebulização, utilizando tubo-T. Os pacientes foram retirados da VM quando o IRRS era < 105. RESULTADOS: Não houve diferença estatisticamente significativa entre os valores do IRRS obtidos nos momentos pré e pós-nebulização. Houve diferença estatística significativa dos valores do IRRS entre CPAP5 e PSV10 (p = 0,008) e entre a modalidade ESP e PSV10 (p = 0,01) no momento pré-nebulização e dos valores do IRRS obtidos entre CPAP5 e PSV10 (p = 0,01) no momento pós-nebulização. CONCLUSÕES: Neste estudo pode-se observar que o valor do IRRS foi superestimado quando obtido na modalidade PSV10. Foi constatado também que não houve necessidade de nebulização de 30 minutos antes da extubação traqueal quando o desmame é realizado com a técnica de redução gradativa da PSV. Este estudo sugeriu que o IRRS foi capaz de prever o sucesso do desmame; entretanto, incapaz de determinar o insucesso quando seu valor fosse < 105. Recomenda-se que o IRRS seja analisado em associação com outros parâmetros preditivos de desmame.

BACKGROUND AND OBJECTIVES: To compare the attainment of the rapid shallow breathing index (IRRS) in modalities PSV 10 cmH2O and PEEP 5 cmH2O (PSV10), CPAP 5 cmH2O (CPAP5) and spontaneous breathing (SB), correlating them with success on failure in the withdrawal of mechanical ventilation (MV). METHODS: Prospective study including 54 patients in MV > 48 hours, submitted to the IRRS in three ventilatory modalities: PSV10, CPAP5 and SB at the moments before and after T-tube spontaneous breathing. The patients were removed from MV when IRRS was < 105. RESULTS: There wasn't statistically significant difference between IRRS values at the moments before and after T-tube SB. There was statistically significant difference IRRS value between the modalities CPAP5 and PSV10 (p = 0.008), and between the modalities SB and PSV10 (p = 0.01) at the moment before T-Tube SB and of IRRS value, gotten between CPAP5 and PSV10 (p = 0.01) at the moment after T-tube SB. CONCLUSIONS: From this sample, it can be observed that IRRS values are overestimated when gotten in modality PSV10. It was also evidenced that there is no need of a 30 min T-tube SB before extubation, when the weaning is performed with the technique of gradual reduction of PSV. This study suggested that IRRS is able to predict weaning success; however it is not able to determine failure when it was < 105. It is recommended that IRRS must be analyzed in association with other predictive weaning parameters.

Implementação, avaliação e comparação dos protocolos de desmame com Tubo-T e Pressão Suporte associada à pressão expiratória final positiva em pacientes submetidos à ventilação mecânica por mais de 48 horas em unidade de terapia intensiva / Implementation, assessment and comparison of the T-Tube and pressure-support weaning protocols applied to the intensive care unit patients who had received mechanical ventilation for more than 48 hours

JUSTIFICATIVA E OBJETIVOS: A retirada precoce da ventilação mecânica dos pacientes das unidades de terapia intensiva (UTI) é importante para a redução da morbimortalidade, porém na prática, os desmames são realizados aleatoriamente. Face à importância desse procedimento, esse estudo avaliou a implementação de protocolos de desmame e comparou dois métodos distintos. MÉTODO: Foram incluídos no estudo 120 pacientes dependentes de ventilação mecânica por mais de 48 horas. O método de Pressão Suporte + PEEP (PSP), foi aplicado aos pacientes em dias pares, constituindo o grupo 1 (GPSP) e em dias ímpares, utilizou-se o método do Tubo-T (TT), formando o grupo 2 (GTT), RESULTADOS: A resposta dos pacientes à extubação revelou evolução semelhante nos dois grupos, porém deixou claro, pela análise estatística do teste Qui-quadrado, o benefício de se utilizar um protocolo de desmame. De todos os pacientes estudados, 109 (90,83 por cento) tiveram sucesso na extubação não sendo necessário nenhum tipo de ventilação não-invasiva dentro de 24 horas após o desmame, enquanto que apenas 11 pacientes (9,17 por cento) necessitaram de ventilação mecânica não-invasiva ou de re-intubação no mesmo período, caracterizando o insucesso do desmame. CONCLUSÕES: A implementação e a padronização de protocolos de desmame da ventilação mecânica, reduziu significativamente o índice de re-intubação na UTI, diminuindo o período de internação e o índice de morbimortalidade, porém neste estudo, não foram encontradas diferenças estatísticas significativas entre os métodos analisados.

BACKGROUND AND OBJECTIVES: Mechanical ventilation incurs significant morbidity and mortality, weaning intensive care unit patients is highly desirable, although it is usuallyconducted in an empirical manner. Thus, this article assessed a weaning protocol implementation and compared two different methods. METHODS: It was carried out a study involving 120 patients who had received mechanical ventilation for more than 48 hours. These patients were randomlyassigned to undergo one of two weaning techniques: pressure-supportventilation + PEEP (PSP) technique, which was applied to the patients in equal days, forming the PSP group (PSPG) and the T-tube method (TT), applied in odd days and forming the TT group (TTG). Standardized protocols were followedfor each technique RESULTS: The patients response to extubation revealed similar progress in both PSP and TT groups, but after the Chi-square statistical test, the benefits of using a weaning protocol was clear. One hundred nine (90.83 percent) of all patients, had a successful weaning and any noninvasive ventilation type was needed in a span time of 24 hours after extubation, and only eleven (9.17 percent), had an unsuccessful weaning. CONCLUSIONS: Although this study didn't show any difference between the two methods applied, we could conclude that, the implementation of standardized weaning protocols can substantially decrease the patient's reintubation rate, promoting a downward trend in mortality and morbidity for these patients and shortening their hospital and intensive care units length of stay.

Comparison of pressure support ventilation or synchronized intermittent mandatory ventilation for respiratory failure after cervical spinal cord injured ZHOU Hao, ZHAO Hai-ping / 中国康复理论与实践

@#ObjectiveTo observe the difference between pressure support ventilation(PSV) and synchronized intermittent mandatory ventilation(SIMV) in cervical spinal cord injury patients with respiratory failure.MethodsThe blood gas analysis,respiratory rate,heart rate,blood pressure and subjective feelings were observed in the same patient under different ventilation(PSV or SIMV).ResultsThere was no significant difference in blood pressure when patients underwent PSV and SIMV.Otherwise,There was significant difference in respiratory rate,heart rate,pH,PaO2,PaCO2 and subjective feelings when patients underwent PSV and SIMV,which showed that of PSV were better.ConclusionThe effect of PSV was better than that of SIMV on respiratory failure after cervical spinal cord injury.

Application of pressure support ventilation on cervical spinal cord injured patients / 中国康复理论与实践

@#ObjectiveTo summarize the application of pressure support ventilation (PSV) on cervical spinal cord injured patients with respiratory dysfunction.MethodSixteen patients were studied.Respiratory rate (RR),tidal volume (VT), minute ventilation (VE),peak inspiration pressure (PIP), dynamic lung conpliance (Cdyn), blood pH value, PaO2 and PaCO2 were measured under the different pressure levels of PSV. ResultAll parameters correlated with the level of PSV. Conclusion Appropriate PSV levels can make the respiratory parameters close to the reasonable level and respiratory functional status for the cervical cord injured patients with respiratory dysfunction.

Effect of Additional 1 hour T-piece Trial on Weaning Outcome to the Patients at Minimum Pressure Support / 결핵

BACKGROUND: Extubation is recommended to he performed at minimum pressure support (PSmin) during the pressure support ventilation (PSV). In field, physicians sometimes perform additional 1 hr T-piece trial to the patient at PSmin to reduce re-intubation risk. Although it provides confirmation of patient's breathing reserve, weaning could be delayed due to increased airway resistance by endotracheal tube. METHODS: To investigate the effect of additional 1 hr T-piece trial on weaning outcome, a prospective study was done in consecutive 44 patients who had received mechanical ventiIation more than 3 days. Respiratory mechanics, hemodymic, and gas exchange measurements were done and the level of PSmin was calculated using the equation (PSmin=peak inspiratory flow rate x total ventilatory system resistance) at the 15cm H2O of pressure support. At PSmin, the patients were randomized into intervention (additional 1 hr T-piece trial) and control (extubation at Psmin). The measurements were repeated at PSmin. during weaning process (in cases of intervention), and after extubation. The weaning success was defined as spontaneous breathing more than 48hr after extuintion. In intervention group, failure to continue weaning process was also considered as weaning failure. RESULTS: Thirty-six patients with 42 times weaning trial were satisfied to the protocol Mean PSmin level was 7.6 (+/-1.9)cm H2O. There were no differences in total ventilation times (TVT), APACHE III score nutritional indices, and respiratory mechanics at PSmin between 2 groups. The weaning success rate and re-intubation rate were not different between intervention group (55% and 18% in each) and control group (70% and 20% in each) at first weaning trial. Work of breathing, pressure time product, arid tidal volume were aggravated during 1 hr T-piece trial compared to those of PSmin in intervention group (10.4+/-1.25 and 1.66+/- 1.08 J/L in work of breathing)(191+/-232 and 287+/-217cm H2Os/m in pressure time product) (0.33+/-0.09 and 0.29+/-0.09 L in tidal volume) (P<0.05 in each). As in whole, TVT, and tidal volume at PSmin were significantly different between the patients with weaning success (246+/-195 hr, 043+/-0.11 L) and the Those with weaning failure (407+/-248 hr, 0.35+/-0.10L) (P<0.05 in each). CONCLUISON: There were no advantage to weaning outcome by addition of 1 hr T-piece trial compared to prompt extubation to the patient at PSmin.

A Comparison of Clinical Efficacy of Weaning Method Between the Mode of Intermittent Mandatory Ventilation and Intermittent Mandatory Ventilation Plus Pressure Support / 결핵

BACKGROUND: Pressure support ventilation(PSV) is a new form of mechanical ventilatory support that assists spontaneous inspiratory effort of an intubated patient with a clinician-selected amount of positive airway pressure. Low level pressure support during inspiration can overcome the resistive component of inspiratory work imposed by ah endotracheal tube. However the clinical efficacy of PSV as a weaning method has not been established yet. Object : The aim of study was to evaluate the efficacy of PSV when it is added to intermittent mandatory ventilation (IMV) in facilitating weaning process compared to IMV mode alone. METHOD: When the subject patients became clinically stable with their arterial blood gas analysis in acceptable range, they underwent weaning process either by IMV alone or by IMV plus PSV. The level of pressure support was held constant through the weaning period. For the patients who required mechanical ventilation for less than 72hr, 2h weaning trial was performed with IMV rate starting from 6/min. For the patients who required mechanical ventilation more than 72 hr, 7 hr weaning retrial was performed with IMV rate starting from 8/min. For the patients who failed three consecutive trials of weaning, retrial of weaning was attempted over 3 days with IMV rate starting from 8/min. Clinical characteristics, APACHE II score and nutritional status were compared. For all patients, heart rate, mean blood pressure and respiratory rate were mornitored for 48 hrs after weaning trial started. RESULTS: The total number of weaning trial was 37 in 23 patients(18 by IMV, 19 by IMV+PSV). Total ventilation time, APACHE II score and nutritional status were not statistically different between the two groups. The weaning success rate were not statistically different(38.3% by IMV, 42.1% by IMV+PSV) and the changes of mean blood pressure, heart rate, respiratory rate during first 48 hours were not different between the two groups. CONCLUSION: Low level PSV when added to IMV for weaning trial does not seem to improve the success rate of weaning from mechanical ventilation. PSV at 10cm H2O did not induce significant physiologic changes during weaning process.

Respiratory Parameters of Pressure Support Ventilation and Synchronized Intermittent Mandatory Ventilation during the Weaning Process / 대한마취과학회지

SIMV (synchronized intermittent mandatory ventilation) is a volume assisted mode which a patient inspiratory demand results in a clinician-controlled tidal volume and flow rate. However, PSV (pressure support ventilation) has the ability to augment spontaneous breaths with a variable amount of inspiratory positive pressure with a clinician-selected level of inspiratory airway pressure. To compare the effects of SIMV and PSV on respiratory function, experiments were performed on 12 stable patients during the weaning process and tidal volume, airway pressure, arterial blood gas tensions, blood pressure, and heart rates were measured during SIMV, and after 2 mins after removal of mechanical ventilation support. The same measurement as SIMV (except mandatory respiratory rates) were performed during PSV. The PSV level was reduced in the 5 cm2O step every 10-15 mins. The results of respiratory parameters and hemodynamic data showed that tidal volume, blood pressure, heart rates, and arterial blood gas tensions were similar, but there were significantly lower ventilatory rates, lower peak airway pressure and lower mean airway pressure during PSVmax than SlMV, and PSV resulted in improved patient comfort. It was concluded that PSV could be used to unload the patients ventilatory muscles and provide an appropriate level of mechanical ventilation support similar to SIMV weaning approaches.