Effects of fenoterol on ventilatory response to hypercapnia and hypoxia in patients with chronic obstructive pulmonary disease

BACKGROUND: It has previously been shown that fenoterol, a beta 2 adrenergic agonist, increases the ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) in normal subjects. The effects of beta 2 adrenergic agonists on chemoreceptors in patients with chronic obstructive pulmonary disease (COPD) remain controversial. This study was designed to examine whether fenoterol increases the HVR and HCVR in patients with COPD. METHODS: The HCVR was tested in 20 patients using a rebreathing method and the HVR was examined using a progressive isocapnic hypoxic method. The HCVR and HVR were assessed by calculating the slopes of plots of occlusion pressure (P0.1) and ventilation (VE) against end tidal carbon dioxide pressure (PETCO2) and arterial oxygen saturation (SaO2), respectively. Spirometric values, lung volumes, and respiratory muscle strength were also measured. The HCVR and HVR were examined after the oral administration of fenoterol (15 mg/day) or placebo for seven days. RESULTS: Fenoterol treatment increased the forced expiratory volume in one second (FEV1) and inspiratory muscle strength. In the HCVR the slope of P0.1 versus PETCO2 was increased by fenoterol from 0.35 (0.23) to 0.43 (0.24) (p < 0.01). Moreover, the P0.1 at PETCO2 of 8 kPa was higher on fenoterol than on placebo (p < 0.05) and the VE was also greater (p < 0.01). In the HVR fenoterol treatment increased the P0.1 at 80% SaO2 from 0.90 (0.72) to 0.97 (0.55) kPa (p < 0.05) while the slopes of the response of P0.1 and VE were not changed. CONCLUSIONS: Fenoterol increases the ventilatory response to hypercapnia in patients with COPD, presumably by stimulation of the central chemoreceptor. The hypoxic ventilatory response is only slightly affected by fenoterol.


     

The Tulip GT® airway versus the facemask and Guedel airway: a randomised,controlled, cross‐over study by Basic Life Support‐trained airway providers in anaesthetised patients

We performed a randomised, controlled, cross‐over study of lung ventilation by Basic Life Support‐trained providers using either the Tulip GT^® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end‐tidal CO₂ > 3.5 kPa and a tidal volume > 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty‐seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end‐tidal CO₂ was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH₂O vs 13.6 (7) cmH₂O respectively (all p < 0.0001). Forty‐seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support‐trained airway providers.     

Stroke volume variation during hemorrhage and after fluid loading: impact of different tidal volumes

BACKGROUND: Previous studies have shown that stroke volume variation (SVV) may be used to assess preload and fluid responsiveness. It is currently under debate, if SVV reliably displays changes in preload during ventilation with clinically used tidal volumes. This study was designed to evaluate whether the predictive value of SVV depends on the tidal volume applied particularly during acute changes of preload. METHODS: We studied 14 anesthetized pigs (35 +/- 2 kg) during changing tidal volumes (5, 10 and 15 ml/kg) at normovolemia (BL), after removal of 500 cc of blood (Hypo) and after retransfusion plus additional 500 cc 6% hydroxyethyl starch (Hyper). SVV was recorded continuously, and global end-diastolic volume (GEDV) was obtained by transpulmonary thermodilution at each experimental stage. RESULTS: GEDV changed significantly comparing the different experimental stages (P < 0.0001). During ventilation with 5 ml/kg, SVV did not change significantly at the different loading conditions. In contrast, during ventilation with both 10 and 15 ml/kg, SVV changed significantly comparing hemorrhage to fluid loading. However, at 15 ml/kg SVV was above the recommended value throughout the experiment. CONCLUSIONS: In this animal model, SVV was not sensitive to acute changes in preload during ventilation with a tidal volume of 5 ml/kg. Moreover, ventilation with high tidal volume may suggest volume loading even after sufficient volume resuscitation.     

Diaphragmatic plication in adult patients with diaphragm paralysis after cardiac surgery.

OBJECTIVE: We investigated the benefit of diaphragmatic plication for weaning from mechanical ventilation in these adult patients. PATIENTS AND METHODS: Four patients underwent diaphragmatic plication for difficulty of weaning from mechanical ventilation due to diaphragmatic paralysis. They were all men with an average age of 70.5 +/- 6.3 years. Three of the patients had undergone cardiac surgeries for coronary artery bypass grafting and one patient ascending aortic replacement for pseudoaneurysm after coronary revascularization. Right diaphragmatic plication (muscle sparing procedure) was performed between 30 to 61 days after cardiac surgery. RESULTS: The mean forced tidal volume improved dramatically from 216 to 415 ml after plication in all patients, and it was possible to discontinue mechanical ventilation from 2 to 12 days after plication. One patient with obstructive respiratory dysfunction died from aspiration pneumonia 15 days after plication. However, postoperative tidal volume in this patient improved to 420 ml and he was able to be weaned from ventilatory support five days after plication. The other three patients were discharged between 26 to 58 days after plication and continue to do well without symptoms. CONCLUSION: Diaphragmatic plication is a useful procedure for treatment of diaphragmatic paralysis in adults as well in children.     

Prognostic factors influencing the outcome in pneumocystis carinii pneumonia in patients with AIDS.

BACKGROUND--Studies attempting to identify the prognostic factors that influence the outcome of Pneumocystis carinii pneumonia (PCP) in patients with AIDS using a multivariate analysis are few. In order to identify those prognostic factors amenable to medical intervention, univariate and multivariate analyses were performed on 102 patients with AIDS suffering a first episode of PCP. METHODS--One hundred and two consecutive patients with AIDS (51% drug abusers, 45% homosexuals, and 4% with other HIV risk factors) admitted to our institution between 1986 and 1989 whose respiratory infection was diagnosed by bronchoalveolar lavage were studied prospectively. RESULTS--The overall mortality was 28%, rising to 79% in those patients who required mechanical ventilation. According to univariate analysis the following variables were related to a poor prognosis: age > 35 years; risk factor for HIV infection other than drug abuse; and AIDS diagnosis confirmed before 1988; PaO2 < 8 kPa at admission; severe acute respiratory failure on admission (PaO2/FIO2 < 20 kPa); mechanical ventilation; antibiotic therapy for PCP other than trimethoprim-sulphamethoxazole; multiple microbial pulmonary infection; serum lactate dehydrogenase (LDH) > 22.5 mukat/l on admission; serum albumin level < 30 g/l. Multivariate analysis showed that only mechanical ventilation was independently associated with a poor outcome. CONCLUSIONS--The mortality of AIDS patients presenting with a first episode of PCP before 1990 was high (28%). The main prognostic factor associated with poor outcome was the requirement for mechanical ventilation due to severe acute respiratory failure.     

The effect of mechanical ventilation tidal volume during pneumoperitoneum on shoulder pain after a laparoscopic appendectomy

Background  

Postlaparoscopic shoulder pain (PLSP) frequently occurs after various laparoscopic surgical procedures. Its mechanism is commonly assumed to be overstretching of the diaphragmatic muscle fibers due to the pressure of a pneumoperitoneum, which causes phrenic nerve-mediated referred pain to the shoulder. Based on this hypothesis, we speculated that during inspiration, the lung could squeeze out the phrenic nerve with carbon dioxide gas against the constantly pressurized abdominal cavity with increasing tidal volume (V_T). Thus, we examined whether mechanical ventilation with a low V_T (LTV, V_T 7 ml/kg) during a pneumoperitoneum might reduce PLSP in patients undergoing laparoscopic appendectomy compared with ventilation with the traditional V_T (TTV, V_T 10 ml/kg).     

Influence of tidal volume for stroke volume variation to predict fluid responsiveness in patients undergoing one-lung ventilation

We designed this study to determine the predictive value for fluid responsiveness of stroke volume variation (SVV) in patients undergoing one-lung ventilation (OLV), ventilated at different tidal volumes. All patients scheduled for pulmonary lobectomy were randomized into two groups according to their tidal volume [group H: tidal volume 8 ml/kg (n = 36); group L: tidal volume 6 ml/kg (n = 37)]. After starting OLV, volume loading was performed by administration of 500 ml 6% hydroxyethylated starch for 30 min. Hemodynamic variables were measured before and after volume loading using the Vigileo-FloTrac system. Patients in both groups were divided into fluid responders and non-responders, and responders were defined as those who demonstrated an increase in cardiac index ≥15% after volume expansion. The area under the receiver operating characteristic curve for SVV to discriminate between responders and non-responders was 0.776 in group H and 0.648 in group L. The optimal threshold value of SVV was 10.5% (sensitivity, 85.7%; specificity, 66.7%) in group H and 8% (sensitivity, 69.5%; specificity, 64.3%) in group L. We found that SVV could predict fluid responsiveness in patients undergoing OLV with acceptable levels of sensitivity and specificity only when tidal volume is at least 8 ml/kg.     

Effect of Mechanical Ventilation on Cytokine Response to Intratracheal Lipopolysaccharide

Background: Mechanical ventilation may cause lung injury through the excitation of an inflammatory response and the release of mediators, such as cytokines. The authors tested the hypothesis that intratracheal lipopolysaccharide amplifies the cytokine response to mechanical ventilation.

Methods: Rat lungs were intratracheally instilled with lipopolysaccharide followed by ex vivo mechanical ventilation for 2 h with low tidal volume of 7 ml/kg with 3 cm H2O positive end-expiratory pressure (PEEP), high tidal volume of 40 ml/kg with zero PEEP, medium tidal volume of 15 ml/kg with 3 cm H2O PEEP, or medium tidal volume and zero PEEP.

Results: In the absence of lipopolysaccharide, lung lavage concentrations of tumor necrosis factor and interleukin 1[beta] but not macrophage inflammatory protein 2 were significantly higher in lungs ventilated at high tidal volume/zero PEEP than at low tidal volume. There was a marked increase in lavage tumor necrosis factor and macrophage inflammatory protein 2 concentrations in lungs ventilated at low tidal volume after exposure to intratracheal lipopolysaccharide at doses of 100 ng/ml or greater. However, in lungs ventilated at high tidal volume, this response to lipopolysaccharide was markedly reduced. In addition, the number of alveolar macrophages recovered in the lavage was significantly lower in lungs ventilated at high tidal volume.     

Effects of bilateral transvenous diaphragm pacing on hemodynamic function in patients after cardiac operations. Experimental and clinical study

The effects of bilateral transvenous diaphragm pacing and intermittent positive-pressure ventilation on hemodynamic function were compared by animal experiment in 18 dogs and by clinical study in 14 patients during the postoperative period after cardiac operations. Aortic, pulmonary arterial, right atrial, and left atrial pressures (transmural) and aortic flow were increased by diaphragm pacing in the canine experiment. In dogs with induced tricuspid insufficiency, aortic pressure, right and left atrial pressures, and aortic blood flow increased, similar to the results obtained in the clinical study. Diaphragm pacing produced a sufficient tidal volume (7.2 to 12 ml/kg) for maintenance of normal blood gas levels in the patients, all of whom recovered spontaneous breathing without any weaning problems after 2 to 6 hours of diaphragm pacing. The catheter electrode used for stimulation was placed 30 mm away from the sinus node to avoid arrhythmias. Respiratory control by diaphragm pacing is hemodynamically superior to that by intermittent positive-pressure ventilation, and its efficacy is expected, especially in critical cases or in diseases or conditions in which the decrease in the load of the right heart affects the hemodynamic status of the patient.     

Noninvasive cardiac output measurement using partial carbon dioxide rebreathing is less accurate at settings of reduced minute ventilation and when spontaneous breathing is present

BACKGROUND: Although evaluation of cardiac output by the partial carbon dioxide rebreathing technique is as accurate as thermodilution techniques under controlled mechanical ventilation, it is less accurate at low tidal volume. It is not clear whether reduced accuracy is due to low tidal volume or low minute ventilation. The effect of spontaneous breathing on the accuracy of partial carbon dioxide rebreathing measurement has not been fully investigated. The objectives of the current study were to investigate whether tidal volume or minute ventilation is the dominant factor for the accuracy, and the accuracy of the technique when spontaneous breathing effort is present. METHODS: The authors enrolled 25 post-cardiac surgery patients in two serial protocols. First, the authors applied three settings of controlled mechanical ventilation in random order: large tidal volume (12 ml/kg), the same minute ventilation with a small tidal volume (6 ml/kg), and 50% decreased minute ventilation with a small tidal volume (6 ml/kg). Second, when the patient recovered spontaneous breathing, the authors applied three conditions of partial ventilatory support in random order: synchronized intermittent mandatory ventilation-pressure support ventilation, pressure support ventilation with an appropriately adjusted rebreathing loop, and pressure support ventilation with the shortest available loop. After establishing steady state conditions, the authors measured cardiac output using both partial carbon dioxide rebreathing and thermodilution methods. The correlation between the data yielded by the two methods was determined by Bland-Altman analysis and linear regression. RESULTS: Cardiac output with the carbon dioxide rebreathing technique correlated moderately with that measured by thermodilution when minute ventilation was set to maintain normocapnia, regardless of tidal volumes. However, when minute ventilation was set low, the carbon dioxide rebreathing technique underreported cardiac output (y = 0.70x; correlation coefficient, 0.34; bias, -1.73 l/min; precision, 1.27 l/min; limits of agreement, -4.27 to +0.81 l/min). When there was spontaneous breathing, the correlation between the two cardiac output measurements became worse. Carbon dioxide rebreathing increased spontaneous tidal volume and respiratory rate (20% and 30%, respectively, during pressure support ventilation) when the rebreathing loop was adjusted for large tidal volume. CONCLUSIONS: During controlled mechanical ventilation, minute ventilation rather than tidal volume affected the accuracy of cardiac output measurement using the partial carbon dioxide rebreathing technique. When spontaneous breathing is present, the carbon dioxide rebreathing technique is less accurate and increases spontaneous tidal volume and respiratory rate.     

Noninvasive Cardiac Output Measurement Using Partial Carbon Dioxide Rebreathing Is Less Accurate at Settings of Reduced Minute Ventilation and when Spontaneous Breathing Is Present

Background: Although evaluation of cardiac output by the partial carbon dioxide rebreathing technique is as accurate as thermodilution techniques under controlled mechanical ventilation, it is less accurate at low tidal volume. It is not clear whether reduced accuracy is due to low tidal volume or low minute ventilation. The effect of spontaneous breathing on the accuracy of partial carbon dioxide rebreathing measurement has not been fully investigated. The objectives of the current study were to investigate whether tidal volume or minute ventilation is the dominant factor for the accuracy, and the accuracy of the technique when spontaneous breathing effort is present.

Methods: The authors enrolled 25 post-cardiac surgery patients in two serial protocols. First, the authors applied three settings of controlled mechanical ventilation in random order: large tidal volume (12 ml/kg), the same minute ventilation with a small tidal volume (6 ml/kg), and 50% decreased minute ventilation with a small tidal volume (6 ml/kg). Second, when the patient recovered spontaneous breathing, the authors applied three conditions of partial ventilatory support in random order: synchronized intermittent mandatory ventilation-pressure support ventilation, pressure support ventilation with an appropriately adjusted rebreathing loop, and pressure support ventilation with the shortest available loop. After establishing steady state conditions, the authors measured cardiac output using both partial carbon dioxide rebreathing and thermodilution methods. The correlation between the data yielded by the two methods was determined by Bland-Altman analysis and linear regression.

Results: Cardiac output with the carbon dioxide rebreathing technique correlated moderately with that measured by thermodilution when minute ventilation was set to maintain normocapnia, regardless of tidal volumes. However, when minute ventilation was set low, the carbon dioxide rebreathing technique underreported cardiac output (y = 0.70x; correlation coefficient, 0.34; bias, -1.73 l/min; precision, 1.27 l/min; limits of agreement, -4.27 to +0.81 l/min). When there was spontaneous breathing, the correlation between the two cardiac output measurements became worse. Carbon dioxide rebreathing increased spontaneous tidal volume and respiratory rate (20% and 30%, respectively, during pressure support ventilation) when the rebreathing loop was adjusted for large tidal volume.     

Cardiopulmonary exercise testing as a predictor of complications in oesophagogastric cancer surgery

Introduction

An anaerobic threshold (AT) of <11ml/min/kg can identify patients at high risk of cardiopulmonary complications after major surgery. The aim of this study was to assess the value of cardiopulmonary exercise testing (CPET) in predicting cardiopulmonary complications in high risk patients undergoing oesophagogastric cancer resection.

Methods

Between March 2008 and October 2010, 108 patients (83 men, 25 women) with a median age of 66 years (range: 38–84 years) underwent CPET before potentially curative resections for oesophagogastric cancers. Measured CPET variables included AT and maximum oxygen uptake at peak exercise (VO₂ peak). Outcome measures were length of high dependency unit stay, length of hospital stay, unplanned intensive care unit (ICU) admission, and postoperative morbidity and mortality.

Results

The mean AT and VO₂ peak were 10.8ml/min/kg (standard deviation [SD]: 2.8ml/min/kg, range: 4.6–19.3ml/min/kg) and 15.2ml/min/kg (SD: 5.3ml/min/kg, range: 5.4–33.3ml/min/kg) respectively; 57 patients (55%) had an AT of <11ml/min/ kg and 26 (12%) had an AT of <9ml/min/kg. Postoperative complications occurred in 57 patients (29 cardiopulmonary [28%] and 28 non-cardiopulmonary [27%]). Four patients (4%) died in hospital and 21 (20%) required an unplanned ICU admission. Cardiopulmonary complications occurred in 42% of patients with an AT of <9ml/min/kg compared with 29% of patients with an AT of ≥9ml/min/kg but <11ml/min/kg and 20% of patients with an AT of ≥11ml/min/kg (p=0.04). There was a trend that those with an AT of <11ml/min/kg and a low VO₂ peak had a higher rate of unplanned ICU admission.

Conclusions

This study has shown a correlation between AT and the development of cardiopulmonary complications although the discriminatory ability was low.     

Artificial Ventilation in Children During Anaesthesia Using a Tidal Volume Ventilator

Standards for artificial pulmonary ventilation at ventilatory frequencies of 15 and 20 cycles per min, (PETCO2 4 +/- 0.5 kPa), were defined in 16 children with healthy lungs and body weights between 2.6 and 22.6 kg. A tidal volume ventilator and balanced anaesthesia were used during abdominal surgery. At f = 20 cycles/min an approximately direct proportionality existed between tidal volume and body weight (VTpat = 12.3 . kg b.w.--2.1, r = 0.99). The mean value VTpat per kg b.w. was 12.1 +/- 1.4 ml/kg. At f = 15 cycles/min, a linear relationship between tidal volume and kg b.w. was recorded (VTpat = 14.6 . kg b.w. + 16, r = 0.97). The mean value VTpat per kg b.w. was 15.9 +/- 1.5 ml/kg. A significant decrease in total compliance was recorded during the initial part of the surgical procedure. A rectilinear relationship existed between total compliance and kg b.w. (CTOT = 11.2 . kg b.w.--12.5, r = 0.95). The mean value CTOT per kg b.w. was 9.7 +/- 0.54 ml/kPa/kg at f = 20. The endotracheal peak pressure maintained a fairly constant pressure level independent of the initial pressure within the ventilator, the tidal volume and the body weight, a phenomenon explained by the hypothesis that the proportional increase in total lung volume and functional residual capacity in the older children compensated for the higher pressures.     

Ultrasonographic evaluation of diaphragm thickness and excursion in patients with cervical spinal cord injury

Objective: To evaluate the diaphragm thickness and excursion in patients with cervical spinal cord injury and reliability of diaphragmatic ultrasonography.Design: A Pilot Case–Control Study.Setting: China Rehabilitation Research Center (CRRC) /Beijing BO AI Hospital.Participants: Sixty participants with cervical spinal cord injury and sixty control participants were eligible for inclusion in this study.Interventions: Ultrasonographic evaluation of the diaphragm.Outcome Measures: All demographic data were evaluated. Diaphragm thickness, thickening ratio, and diaphragm excursions were assessed at the end of quiet tidal breathing and maximal inspiration. The reliability of inter- and intra-ultrasonography operators were evaluated.Results: Diaphragm thickness was significantly higher in patients with cervical spinal cord injury than the control group (P < 0.001). Diaphragmatic excursion of the right hemidiaphragm was significantly greater in patients with cervical spinal cord injury than the control group (P < 0.001) at the end of quiet tidal breathing. No difference was found in diaphragmatic excursion between two groups (P = 0.32) at the end of maximal inspiration. No significant difference was shown between two groups in thickening ratio. Intraclass correlation coefficients of inter-and intra-ultrasonography operators for the thickness and excursions of the diaphragm were greater than 0.93.Conclusion: Compared with the control group the diaphragm in patients with cervical spinal cord injury is hypertrophied and the diaphragm excursion is greater. Ultrasound is a highly reliable tool for the evaluation of diaphragm thickness and excursion in patients with cervical spinal cord injury.Trial Registration: This trail was registered in Chinese Clinical Trial Registry (NO. ChiCTR-ROC-17010973).     

Use of high frequency jet ventilation in extracorporeal shockwave lithotripsy

High frequency jet ventilation (HFJV) was used in 68 patients which were treated with extracorporal shock wave lithotripsy (ESWL) because of stone diseases in the upper urinary tract. The question was whether HFJV in combination with a semiclosed conventional circle system offered a practicable and safe technique to minimize the oscillations which are proportional to the applied tidal volume and to the diaphragmatic movements. With IPPV the mean distance of the stone movement was 32 mm, whereas with the application of HFJV the stones oscillated around their resting position within limits of 2 to 3 mm (ventilation frequency: 200-300/min, driving pressure: 0.6-1.1 bar, tidal volume: 3-8 1/min). The effectiveness of HFJV was monitored by the end-tidal carbon dioxide tension (PeCO2) during intermittently conventional ventilation with "adequate" tidal volumes (TV 15 ml/kg bw). The correlation between PeCO2 and simultaneous measured PaCO2 was r = 0,91. The application of HFJV enhances the efficiency of ESWL. So the treatment of stones of the upper urinary tract can be varied by more subtle dosage of the incoming shock wave energy and by stabilisation of the stones in the underlying ellipsoid of the energy focus.     

Effect of mechanical ventilation on cytokine response to intratracheal lipopolysaccharide

BACKGROUND: Mechanical ventilation may cause lung injury through the excitation of an inflammatory response and the release of mediators, such as cytokines. The authors tested the hypothesis that intratracheal lipopolysaccharide amplifies the cytokine response to mechanical ventilation. METHODS: Rat lungs were intratracheally instilled with lipopolysaccharide followed by ex vivo mechanical ventilation for 2 h with low tidal volume of 7 ml/kg with 3 cm H2O positive end-expiratory pressure (PEEP), high tidal volume of 40 ml/kg with zero PEEP, medium tidal volume of 15 ml/kg with 3 cm H2O PEEP, or medium tidal volume and zero PEEP. RESULTS: In the absence of lipopolysaccharide, lung lavage concentrations of tumor necrosis factor and interleukin 1 beta but not macrophage inflammatory protein 2 were significantly higher in lungs ventilated at high tidal volume/zero PEEP than at low tidal volume. There was a marked increase in lavage tumor necrosis factor and macrophage inflammatory protein 2 concentrations in lungs ventilated at low tidal volume after exposure to intratracheal lipopolysaccharide at doses of 100 ng/ml or greater. However, in lungs ventilated at high tidal volume, this response to lipopolysaccharide was markedly reduced. In addition, the number of alveolar macrophages recovered in the lavage was significantly lower in lungs ventilated at high tidal volume. CONCLUSION: Ventilation strategy can modify lung cytokine responses to lipopolysaccharide, likely through an effect on the alveolar macrophage population.     

A diaphragmatic retroperitoneal cyst

Diaphragmatic lesions are usually congenital bronchogenic cysts. A patient with a known diaphragmatic cyst presented with new onset right upper quadrant pain. Repeat imaging showed enlargement of the cyst, the CA19–9 cancer marker was raised at 312iu/ml (normal: <27iu/ml) and positron emission tomography combined with computed tomography showed focally increased uptake in the cystic wall. In view of symptoms and risk of neoplasia, the lesion was excised. Histology showed a benign epidermoid cyst. Features falsely suggesting neoplasia have been reported previously with benign splenic cysts but not with a benign diaphragmatic epidermoid cyst.     

Ventilation in the unprotected airway

The fear of acquiring infectious diseases has resulted in a reluctance to perform mouth-to-mouth ventilation among healthcare professionals and the lay public. However, the benefit of initiating lifesaving resuscitation in a patient in cardiopulmonary and/or respiratory arrest greatly outweighs the risk for secondary infection in the rescuer or the patient. The distribution of ventilation volume between lungs and stomach in the unprotected airway depends on patient variables (such as lower oesophageal sphincter pressure, airway resistance and respiratory system compliance) and the technique applied by the healthcare professional while performing basic or advanced airway support (such as head position, inspiratory flow rate and time and, especially, upper airway pressure). The combination of these variables determines the gas distribution between the lungs and the oesophagus and, subsequently, the stomach. During bag-valve-mask ventilation of a patient in respiratory or cardiac arrest with oxygen supplementation (⩾ 40% oxygen), a tidal volume of 6–7 ml/kg (∼500 ml) given over 1–2 seconds until the chest rises is recommended. For bag-valve-mask ventilation with room-air, a tidal volume of 10 ml/kg (700–1000 ml) in an adult given over 2 seconds until the chest rises is recommended. During mouth-to-mouth ventilation, a breath over 2 seconds sufficient to make the chest rise clearly (tidal volume of ∼10 ml/kg (∼700–1000 ml in an adult) is recommended.     

胸科手术中单肺通气期间不同通气方式的比较

目的 观察胸科手术病人麻醉中单肺通气（ＯＬＶ）期间不同通气方式的效果。方法 １０例择期胸科手术成年病人,ＡＳＡⅠ～Ⅱ级,在ＯＬＶ期间首先采用全潮气量（１０ｍｌ／ｋｇ）不加ＰＥＥＰ,随后采用半潮气量（５ｍｌ／ｋｇ）同时施加７ｃｍＨ２Ｏ ＰＥＥＰ两种通气方式,保持每分通气量不变。在开胸后ＯＬＶ前,ＯＬＶ时采用敏种通气方式后３０ｍｉｎ,以及恢复双肺通气（ＴＬＶ）后３０ｍｉｎ分别进行血气分析,同时监测气道     

Neutrophil stimulation with granulocyte colony-stimulating factor worsens ventilator-induced lung injury and mortality in rats

BACKGROUND: Based on the association between the neutrophil and ventilator-induced lung injury, the authors hypothesized that neutrophil inhibition with fucoidin would be beneficial and stimulation with granulocyte colony-stimulating factor (G-CSF) would be harmful in a rat model of lethal ventilator-induced lung injury. METHODS: Animals (n = 111) were randomly assigned to be pretreated with fucoidin, G-CSF, or placebo (control) before 4 h of low-tidal-volume (10 ml/kg) or high-tidal-volume (40 ml/kg) mechanical ventilation. RESULTS: All low-volume animals survived. With high volumes, compared with controls, fucoidin did not improve survival (3 of 20 control animals and 5 of 20 fucoidin animals died; P = 0.51) but G-CSF significantly worsened it (18 of 22 animals died; P < 0.001). Circulating neutrophils were increased early with G-CSF and late with fucoidin with low and high tidal volumes (P < 0.05 for each treatment and tidal volume). Fucoidin decreased lung neutrophils, but these were only significant with high tidal volumes, whereas G-CSF increased lung neutrophils but only significantly with low tidal volumes (P < or = 0.01 for each). Fucoidin did not alter any cardiopulmonary measure significantly. Compared with control, G-CSF increased airway pressures with high tidal volumes and worsened lung edema and arterial oxygen with both tidal volumes (P < 0.05 for each). CONCLUSIONS: In this model, neutrophil stimulation by G-CSF increased lung dysfunction and with high tidal volumes worsened survival rates. Extrapolated clinically, neutrophil stimulation either by agents such as G-CSF or conditions such as sepsis may aggravate ventilator-induced lung injury.