Effect of the alveolar recruitment manoeuvre on haemodynamic parameters in patients with acute respiratory distress syndrome: relationship with oxygenation

Background and objective: Although the alveolar recruitment manoeuvre (ARM) is considered to be an optimal method of recruiting collapsed alveoli in a short period, the haemodynamic effects of the ARM have not been investigated. The aim of this study was to assess whether the ARM causes haemodynamic instability in patients with ARDS, and any relationship this might have with arterial oxygenation. Methods: Twenty‐eight patients with ARDS (16 responders and 12 non‐responders), who were admitted to the medical intensive care unit of a university‐affiliated hospital, were enrolled in the study. ARM, using the extended sigh method, was performed within 48 h of the onset of ARDS. Haemodynamic parameters were measured at baseline, during the ARM, and at 2 min, 30 min and 1 h after the ARM. Results: Responders and non‐responders showed no significant changes in blood pressure or cardiac index during or after ARM. Mean pulmonary artery pressure (MPAP), pulmonary vascular resistance index (PVRI) and right ventricular stroke work index (RVSWI) were transiently increased compared with baseline, in responders and non‐responders. During and after ARM, the systemic vascular resistance index was significantly higher in non‐responders than in responders. Conclusions: Some haemodynamic parameters (MPAP, PVRI and RVSWI) changed significantly during ARM. However, these haemodynamic changes were minimal, transient and probably have no clinical significance.     

Waveform analysis for the detection of airways obstruction in man

The mathematical analysis of respiratory signals has been suggested as a safe noninvasive method for the diagnosis of airways obstruction in man. It involves (i) recording the respired air volume against time waveform for the deep and rapid breathing manoeuvre, (ii) digitising the analogue waveform and (iii) processing the data on a digital computer. The fast Fourier transform technique is used to process the data to yield the amplitude/power spectrum of the waveform. It is shown that, with the aid of the spectrum, it is possible to distinguish between the breathing waveform of a patient suffering from airways obstruction (AWO) and a normal subject (free from AWO). The paper presents results based on a study of the analysis of the respiratory volume signals of 85 subjects (both normals and patients) and suggests that this technique be used as a mass screening diagnostic test for AWO. The processing of the signals and subsequent diagnosis can be performed online with the aid of a microprocessor-based computer system.     

Valsalva constrictor and heart rate reflexes in subjects with essential hypertension and with normal blood pressure

1. The haemodynamic and heart rate responses to graded expiratory pressures were studied during Valsalva manoeuvres of standard 30 s duration in two groups of normotensives in the upper (n= 10) and lower (n= 9) halves of the ‘normal’ blood pressure range, and in a group of essential hypertensive subjects with minimal complications (n= 10). Haemodynamic variables were arterial, atrial and peripheral vein pressures, cardiac output and total peripheral resistance. 2. Reflex and mechanical effects of the manoeuvre were assessed in each subject from changes in the relationship between the expiratory pressure and circulatory responses before autonomic blockade, after cardiac effector block and after ‘total’ blockade. 3. The relationships between expiratory pressure and central and peripheral vein pressures were not changed by autonomic blockade, indicating that they depended on mechanical factors. In hypertensives the rise in venous pressures per unit expiratory pressure was significantly smaller than in normotensive subjects. 4. The expiratory pressure-related rise in total peripheral resistance was reflex and was similar in magnitude in all groups before autonomic blockade. However, after cardiac effector blockade the rise was greatest in the hypertensive subjects. The sensitivity of the constrictor response was related to the subjects’ resting total peripheral resistance index when measurements from all subjects were included. 5. The reflex heart rate responses of the hypertensives showed: (i) accentuation of the bradycardia at the start of forced expiration; (ii) an increased threshold for eliciting tachycardia during the latter part of the manoeuvre; and (iii) attenuation of the ‘overshoot’ bradycardia following release of expiratory pressure. 6. The differences between the responses of hypertensives and normotensives were relatively small and probably depended at least partly on differences in venous filling, structural differences of resistance vessels and different afferent inputs through arterial and cardiopulmonary baroreceptors.     

Tachycardia and coronary blood flow: non-invasive estimation during Valsalva manoeuvre and exercise

Summary. Simultaneous changes in cycle length and coronary blood flow were studied during Valsalva manoeuvre and supine cycloergometer exercise test in 10 male patients (mean age 4812 years) who had successfully undergone myocardial revascularization by surgical anastomosis of the left internal mammary artery on the left anterior descending coronary artery. Blood velocity curves in the left internal mammary artery were obtained by a non-invasive continuous-wave Doppler probe at rest, in the last phase of the expiratory effort of the Valsalva manoeuvre and at the maximum load attained during the exercise test. Mean arterial pressure by sphygmomanometer, and cardiac cycle length on the basis of Doppler recording were measured. Mean blood velocity, the length of the blood column entering the coronary bed at each cycle (cardiac cycle times mean velocity), an index of blood cell acceleration (the ratio of mean velocity to cardiac cycle), and an index of coronary resistance (the ratio of mean pressure to mean velocity), were calculated. For approximately the same change in cycle length, coronary resistance decreased in exercise, with an increased mean velocity, but increased in Valsalva, with no changes in mean velocity. The length of the blood column entering the coronary bed at each cycle was unchanged in exercise, with a marked increase in the acceleration index, while it decreased in Valsalva. Therefore, we hypothesize that tachycardia has a limiting effect on sympathetic coronary constriction in Valsalva when cardiac external work is decreased, and an additional vasodilatory effect on coronary bed in exercise when external work is increased.,     

Evidence that imipramine-induced postural hypotension may be centrally mediated

The acute effects of imipramine upon cardiovascular reflexes have been studied in normal volunteers. Respiratory sinus arryhthmia, blood pressure and heart rate responses to standing, heart rate response to Valsalva's manoeuvre and the heart rate and blood pressure responses to isometric exercise were measured before and after 100 mg and 40 mg imipramine orally on separate occasions. Neither dose had an appreciable effect upon respiratory sinus arrhythmia (RSA), heart rate response to Valsalva or the responses to isometric exercise. Imipramine caused dose-related rises in resting heart rate and blood pressure. In view of the unchanged RSA these cannot be attributed to vagal blockade and may reflect peripheral noradrenaline reuptake inhibition. Imipramine profoundly altered the heart rate response to standing in a dose-related manner. This suggests an impairment of the orthostatic reflex. The presence of normal responses to the Valsalva manoeuvre and isometric exercise suggests that peripheral mechanisms were intact, and it is therefore likely that impairment of the orthostatic reflex is due to the effect of imipramine upon central monoaminergic neurones normally involved in this response.     

Multilobular Cavernous Malformation: Report of Two Cases

Summary The authors report two cases of cavernous malformation characterized by a multilobular appearance on magnetic resonance images. At surgery, the malformations consisted of several nests of angiomatous components that were separated by intervening brain tissue and connected with each other by tiny vessels. This basic configuration seems to explain the unexpected postoperative recurrence of cavernous malformations and/or rebleeding from the residual lesions.     

信息化卫勤演练模式设计与应用

本文分析了卫勤演练的现状,针对存在的问题,从演练内容、方法和工具3方面设计了信息化卫勤演练新模式,将卫勤指挥与分队保障相结合,网上演练与实兵演练相结合,突出了信息化装备的使用。通过在院校卫勤教学中的应用,推动了院校教育向信息化条件下转变,探索了信息化条件下的联合卫勤保障新模式。     

Plasma dihydroxyphenylalanine (DOPA) is independent of sympathetic activity in humans

To clarify the origin of plasma DOPA (3,4-Dihydroxyphenylalanine), the relationship between plasma DOPA and acute or chronic changes in sympathetic activity has been studied. Plasma DOPA and noradrenaline (NA) concentrations were measured by reverse-phase high-performance liquid chromatography with electrochemical detection. Administration of clonidine to healthy men decreased plasma NE markedly compared to no drug. Plasma DOPA decreased slightly but significantly with time, but values were identical after clonidine compared to no drug. Baseline plasma NE concentrations were significantly reduced in diabetic patients with autonomic neuropathy compared to diabetics without neuropathy, whereas baseline plasma DOPA concentrations were similar in the three groups investigated: 6.55 (5.03-7.26, median [interquartile range], n = 8) nmol l-1 in diabetics with neuropathy, 7.41 (5.79-7.97, n = 8) nmol l-1 in diabetics without neuropathy, and 6.85 (5.58-7.36, n = 8) nmol l-1 in controls. No relationship was obtained between baseline values of plasma NE and plasma DOPA. Plasma DOPA did not change in the upright position, whereas plasma NE increased significantly. Our results indicate that plasma DOPA is not related to sympathetic activity and may be of non-neuronal origin.     

Combined incisional ropivacaine infiltration and pulmonary recruitment manoeuvre for postoperative pain relief after diagnostic hysteroscopy and laparoscopy

Background Preoperative incisional local anaesthesia with ropivacaine is a common method of providing postlaparoscopy pain relief.The pulmonary recruitment manoeuvre also provides pain relief,but the combined effect of these two methods on pain following laparoscopic procedures has not been reported.We investigated the efficacy of combining local anaesthetic infiltration of ropivacaine with pulmonary recruitment manoeuvre on postoperative pain following diagnostic hysteroscopy and laparoscopy.Methods This prospective,randomized,controlled study involved 60 patients divided into two groups （n=30,each）.Group 1 received 20 ml of 0.5％ ropivacaine injected peri-incisionally preoperatively,with intra-abdominal carbon dioxide removed by passive deflation.Group 2 received 20 ml of 0.5％ ropivacaine injected peri-incisionally with five manual inflations of the lungs with a positive-pressure ventilation of 40 cmH2O at the end of surgery.The last inflation was held for 5 seconds.The intensity of postoperative incisional and shoulder pain was evaluated using a numerical rating scale at 0,2,4,8,12,24 and 48 hours postoperatively by an independent blinded anaesthesiologist.Tramadol was given postoperatively for analgesia.Results Compared with group 1,incisional ropivacaine infiltration combined with pulmonary recruitment manoeuvre significantly reduced dynamic pain at 0 hour,4 hours,and 24 hours postoperatively （4.1 ± 2.2 vs.2.1 ± 1.9,P=0.002;2.7 ± 2.7 vs.1.2 ± 1.3,P=0.035; and 3.5 ± 2.1 vs.2.1 ± 1.8,P=0.03,respectively）.Static incisional pain was significantly relieved at 0 hour,2 hours,and 24 hours postoperatively （3.1 ± 1.7 vs.1.6 ± 1.3,P=0.001; 1.4 ± 1.3 vs.0.5 ± 0.8,P=0.012;and 2.3 ± 1.9 vs.1.0 ± 1.5,P=0.038,respectively）.Group 2 had more patients without shoulder pain （P＜0.05） and fewer requiring tramadol （P＜0.05）.Conclusion Ropivacaine with pulmonary recruitment manoeuvre provided simple and effective pain relief after diagnostic hysteroscopy and laparoscopy.