Combining ventilation efficiency and peak systolic blood pressure in prognostic assessment of patients with chronic heart failure / 中华全科医师杂志

Objective:To analyze the value of minute ventilation to carbon dioxide production slope (VE/VCO 2 slope) combined with peak systolic blood pressure (SBP) in predicting prognosis for patients with chronic heart failure (CHF). Methods:A total of 170 patients with CHF who visited the Cardiac Rehabilitation Center of Tongji Hospital Affiliated to Tongji University and completed cardiopulmonary exercise test from March 2007 to December 2018 were enrolled in the study. The clinical data, cardiopulmonary exercise testing results and follow-up information of patients were collected to explore the predictors of all-cause mortality in patients with CHF.Results:The median follow-up time was 647 (182-1 764) days. All-cause death occurred in 34 patients. Compared with surviving patients, the proportion of diabetes and angiotensin-converting enzyme inhibitor/angiotensin Ⅱ receptor blocker (ACEI/ARB) use in fatal patients was significantly higher ( P<0.01). The VE/VCO 2 slope and peak SBP*VE/VCO 2 in the fatal patients were significantly higher, and the peak oxygen consumption (peak VO 2) was lower than those in the surviving patients ( P<0.01). The areas under the receiver operating characteristic curve (AUC) of VE/VCO 2 slope and peak SBP*VE/VCO 2 in predicting all-cause mortality in patients with CHF were 0.648 ( P=0.008) and 0.681 ( P=0.001), respectively; the optimal thresholds were >40.95 ( P=0.008) and > 5 423.50 mmHg (1 mmHg=0.133 kPa, P=0.006), the sensitivity was 0.559 and 0.588, and the specificity was 0.728 and 0.735, respectively. Multivariate Cox regression analysis showed that after adjusting for age, gender, diabetes and ACEI/ARB use, VE/VCO 2 slope ( HR=2.12, P=0.036) and peak SBP*VE/VCO 2 ( HR=2.42, P=0.016) were independent risk factors for all-cause mortality in patients with CHF. Conclusion:Compared to the traditional index VE/VCO 2 slope, a novel index peak SBP* VE/VCO 2 provides a relatively better predictive value for all-cause death of CHF patients.

Inductive plethysmography potential as a surrogate for ventilatory measurements during rest and moderate physical exercise

Background: Portable respiratory inductive plethysmography (RIP) systems have been validated for ventilatory assessment during resting conditions and during incremental treadmill exercise. However, in clinical settings and during field-based exercise, intensity is usually constant and submaximal. A demonstration of the ability of RIP to detect respiratory measurements accurately during constant intensity conditions would promote and validate the routine use of portable RIP devices as an alternative to ergospirometry (ES), the current gold standard technique for ventilatory measures. Objective: To investigate the agreement between respiratory variables recorded by a portable RIP device and by ES during rest and constant intensity exercise. Method: Tidal volume (VT), respiratory rate (RR) and minute ventilation (VE) were concurrently acquired by portable RIP and ES in seven healthy male volunteers during standing rest position and constant intensity treadmill exercise. Results: Significant agreement was found between RIP and ES acquisitions during the standing rest position and constant intensity treadmill exercise for RR and during the standing rest position for VE. Conclusion: Our results suggest that portable RIP devices might represent a suitable alternative to ES during rest and during constant submaximal exercise.

Characterization of oleic acid-induced acute respiratory distress syndrome model in rat.

Animal studies using oleic acid (OA) model to produce acute respiratory distress syndrome (ARDS) have been inconsistent. Therefore, the present study was undertaken to establish an acute model of ARDS in rats using OA and to characterize its effect on cardio-respiratory parameters and lethality. The trachea, jugular vein and femoral artery of anesthetized adult rats were cannulated. A dose of OA (30-90 µL; iv) was injected in each animal and changes in respiratory frequency (RF), heart rate (HR) and mean arterial pressure (MAP) were recorded. Minute ventilation and PaO2/FiO2 (P/F) ratio were also determined. At the end, lungs were excised for determination of pulmonary water content and histological examination. At all doses of OA, there was immediate decrease followed by increase in RF, however at 75 and 90 µL of OA, RF decreased abruptly and the animals died by 63 ± 8.2 min and 19 ± 6.3 min; respectively. In all the groups, HR and MAP changes followed the respiratory changes. The minute ventilation increased in a dose-dependent manner while the values of P/F ratio decreased correspondingly. Pulmonary edema was induced at all doses. Histological examination of the lung showed alveolar damage, microvascular congestion, microvascular injury, infiltration of inflammatory cells, pulmonary edema and necrosis in a dose-dependent manner. With these results, OA can be used to induce different grades of ARDS in rats and OA doses of 50, 60 and 75 µL resemble mild, moderate and severe forms of ARDS respectively. Hence, OA model serves as a useful tool to study the pathophysiology of ARDS.

The minute ventilation recovery time used as a predictor of weaning in patients with chronic obstructive pulmonary disease / 中华急诊医学杂志

Objective To explore the value of minute ventilation recovery time (VERT) as a weaning predictor in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD).Methods A prospective study was performed from March 2008 to July 2012.Fifty-two COPD patients under mechanical ventilation for more than 48 hours in our RICU tolerated a spontaneous breathing trial (SBT) and were ready for planned extubation.After SBT,these patients were placed back on their pre-SBT ventilator settings for up to 25 minutes,during which VERT was obtained.VERT was defined as the time for minute ventilation to return to baseline measured before SBT.Respiratory rate,tidal volume,minute ventilation and respiratory rate/tidal volume ratio were also obtained before SBT and just after SBT.Arterial blood gas data were measured and recorded before weaning.According to the weaning outcome,the patients were classified as successful group (40 cases) or failed group (12 cases).VERT and other quantitative variables were compared using t test.A multiple logistic regression was performed to explore possible factors associated with the weaning outcome.The sensitivity and specificity of VERT for predictive capacity in weaning were assessed using ROC cure.Results VERT and respiratory rate after SBT were significantly different between two groups.Multiple logistic regression revealed that VERT was the only predictor associated with weaning outcome (b =0.282,P ＜0.001).The area under ROC curve for VERT was 0.957 (95％ CI:O.907-1.008).With a cut-off value of 10.5 minutes,the sensitivity and specificity of VERT for predicting weaning failure were 1.0 and 0.85,respectively.Conclusions VERT may be a new predictor for extubation and determination of mechanical ventilation weaning in patients with COPD.VERT is a variable to be easily measured thereby being conveniently used in clinical practice.

Relationship between waist to hip ratio and static lung volumes in adults / 中国病理生理杂志

AIM: The study is designed to probe for the relationship between waist to hip ratio(WHR)and static lung volumes of adults. METHODS: In July-October 2008, 1 307 healthy adults(372 males and 935 females)were selected in Heilongjiang province by means of questionnaire and physical examination. The height, weight, WHR, fat mass, percentage body fat and lung function were measured, and then grouped according to the standard of classification of WHR(central obesity male WHR ≥ 0.86, female ≥ 0.82)for analysis of the relationship between WHR and static lung volume. RESULTS: WHR was found, regardless of sex, to tend to go up with the increase in age and BMI(P<0.01), and both the fat mass and percentage body fat of the central obesity group were higher than those in the group with normal WHR(P<0.01). An independent negative correlation was found(P<0.05), also regardless of sex, between the WHR with expiratory reserve volume(ERV)in all these adults. ERV in central obesity group was lower than that in the group with normal WHR(P<0.05). Compared to the normal group, ERV in the central obesity group decreased by 11% for males and 8% for females(P<0.05). However, with regard to the relationship between WHR and VT, IC, MV, and VC, gender differences were found. For the males, a significant independent positive correlation was observed between WHR and IC(P<0.05), with IC of the central obesity group 6% higher than that in the group with normal WHR(P<0.05). For the females, significant independent positive correlation was found between WHR and MV(P<0.05), with the VT and MV of the central obesity group 7% and 6% higher(P<0.05), respectively, than that in the group with normal WHR. CONCLUSION: WHR is in an independent negative correlation with ERV. The elevation of WHR may play a role in the impairment of respiratory function. Its occurrence is accompanied by a rise of IC for the male and a rise of MV for the female. These changes in the two genders could be associated with the decrease in arterial oxygen tension caused by the decrease of ERV.

Correlation of Tracheal Cross-sectional Area with Parameters of Pulmonary Function Test in COPD / 결핵

BACKGROUND: Maximal expiratory flow rate is determined by the size of airway, the elastic recoil pressure and the collapsibility of airway in the lung, and one of major functional impairments of emphysema, which represents COPD, is the obstruction of expiratory flow. Neverthless, expiratory narrowing of upper airway may be recruited as a mechanism for minimizing airway collapse, and maintaining lung volume and hyperinflation by an endogenous positive end-expiratory pressure in patients with airflow obstruction. We investigated the physiologic role of trachea in respiration in emphysema. METHOD: We collected 20 patients with emphysema (which was diagnosed by radiologic and physio logic criteria) from January to August in 1997 at Seoul Municipal Boramae Hospital, and chest roentgenogram, high resolution computed tomography(HRCT), and pulmonary function tests including arterial blood gas analysis and body plethysmography were done from each patient. Cross-sectional area of trachea was measured according to the respiratory cycle on the level of aortic arch by HRCT and calibrated with body surface area. We compared this calibrated area with such parameters of pulmonary function tests as PaCO2, PaO2, airway resistance, lung compliance and so on. RESULTS: Expiratory cross-sectional area of trachea has significant correlation with PaCO2 (r=-0.61, p0.05 with PaCO2, r=0.26, p>0.05 with PaO2, and r=0.44, p>0.05 with minute ventilation). Minute ventilation has significant correlation with tidal volume (r=0.45, p0.05). Cross-sectional area of trachea doesn't have any significant correlation with other parameters of pulmonary function such as FEV1, FVC, FEV1/FVC, peak expiratory flow, residual volume, diffusing capacity, airway resistance, and lung compliance, whether the area is expiratory or inspiratory. CONCLUSION: Cross-sectional area of trachea narrowed during expiration in emphysema and its expiratory area has significant correlation with PaCO2, PaO2, and minute ventilation.

The Factor that Determines Mechanical Ventilation during Cesarean Section under General Anesthesia: Weight before pregnancy vs. weight during delivery / 대한마취과학회지

BACKGROUND: During general anesthesia the adult patient's tidal volume is determined by patient's weight. Therefore patients with severe ascites, huge abdominal mass or pregnancy have considerable ventilatory change during the operation because the great change in their body weight, that might cause unwanted respiratory alkalosis or acidosis. The purpose of this study is to identify the effects of such changes in ventilation between pre-delivery and post-delivery periods during the cesarean section. METHODS: Eighteen 36weeks or older pregnant patients (ASA 1), scheduled for elective cesarean section under general anesthesia, are selected for the study. PhysioFlex was used for ventilation. Pre-induction maternal gas analysis were performed in all cases. They were randomly divided into two groups according to the ventilator setting for minute ventilation, one set by pre-pregnant weight (Group 1) and the other by pregnant (term) weight (Group 2). Blood gas analysis were performed 5 minutes after induction and 20 minutes after delivery. End-tidal CO2 and inspiratory airway pressure were also measured. RESULTS: All patients show mild hyperventilation with normal acid-base status at pre-induction period. There were no significant differences in arterial PCO2 value between two groups. Group 1 shows mild metabolic acidosis compared with group 2 (by pH at 20 minutes after delivery). CONCLUSION: Term(just prior to operation) body weight rather than pre-pregnant weight is preferable for ventilator setting in the case of cesarean section under general anesthesia.

The Effect of Cuff Volume of Laryngeal Mask Airway on Cuff Pressure and Ventilation / 대한마취과학회지

BACKGROUND: The cuff inflation of laryngeal mask airway (LMA) with excessive volume of air may injure soft tissue and nerves around hypopharynx because of high cuff pressure. But it is not well known about adequate cuff volume of LMA. The cuff inflation of LMA in hypopharynx accomodate pharynx, so various injection volume may differ in sealing effect. This may influence ventilation. This study was proposed to investigate the effect of cuff volume on cuff pressure and ventilation when LMA inserted. METHODS: Fifteen male patients were inserted with #4 LMA, fifteen female patients were inserted #3 LMA. For male patients, 10, 20, 30 and 40 ml of air were injected into cuff of LMA and 10, 15, 20 and 25 ml for female patients. Cuff pressure, minute ventilation and airway pressure were randomly measured. RESULTS: Volume of injected into cuff and cuff pressure of LMA were closly related. But minute ventilation and airway pressure were not related with injected air volume of LMA. CONCLUSION: Excessive volume of air injected to LMA cuff was not beneficial to ventilation. So minimal sealing cuff volume under maximal recommended volume of LMA may reduce the incidence of complications associated with high cuff pressure.

Physiological Effects of Local Bubbling during Bathing / 日本温泉気候物理医学会雑誌

Physiological effects of local bubbling during bathing have been evaluated from three series of experiments. In the first series, four male subjects bathed for 6 minutes. and their chests were exposed to bubbling at rates of 13, 20 and 45<i>l</i>/min. Water temperature (Tw) was initially controlled to 37 and 42°C, and then adjusted by the subjects to optimum Tw. In the second series, four male subjects bathed in 39°C water. Four sites (chest, back, lower back, and shin) were exposed to bubbling at rates of 8, 13<i>l</i>/min and the rate of 8<i>l</i>/min alternating with the rate of 13<i>l</i>/min at second intervals. In the last series, four male subjects bathed in 39°C water and two sites (chest and lower back) were exposed to bubbling at rates of 13, 33 and 46<i>l</i>/min. Blood pressure, heart rate, rectal and skin temperatures, minute ventilation were monitored on each occasion.<br>Subjectively determined optimum Tw was about 39°C in the case of initial Tw of 37°C, and was 41°C in the case of initial Tw of 42°C. Systolic blood pressure decreased while heart rate and minute ventilation increased during bathing. Physiological variables changed significantly when chest and lower back were exposed to bubbling at the rate of 33<i>l</i>/min. The increase in rectal temperature after bathing is likely proportional to the decrease in skin temperature at the lower extremities. It is, therefore, suggested from these results that local bubbling to chest/back may be most effective when the rate of bubbling is controlled in the range of 20-35<i>l</i>/min at Tw of 39°C.

Working Principle and Application of Adaptive Support Ventionlation / 医疗卫生装备

By introducing the basic concept and principle, the advantages and characteristics of ASV technology are highlighted. Based on clinical application, suggestions on how to correctly set ASV parameters are given.