生理呼吸功指导呼吸机脱机的临床意义

目的:评价生理呼吸功(WOBphy)对机械通气患者脱机的指导作用。方法:测定患者呼吸功(WOBt)和器械附加功(WOBimp)。并推算WOBphy。不符合常规脱机标准者,如WOBphy<0.70J/L,仍立即脱机拔管。结果:41例患者中28例符合常规脱机际准(常规组),WOBphy均<0.70J/L,拔管后1例再插管。13例患者不符合常规脱机标准(非常规组),WOBt高达1.37±0.50J/L,但 WOBphy均于0.70J/L,立即拔管后仪1例再插管。结论:以WOBphy<0.70J/L作为脱机标准,比常规脱机际准更准确。     

Propofol induces bronchodilation in mechanically ventilated chronic obstructive pulmonary disease (COPD) patients

The aim of this study was to evaluate the effects of propofol administration (2 mg · kg^-1 i.v.) on the airways resistances and respiratory mechanics of patients affected by COPD exacerbation, requiring mechanical ventilation. Twenty patients required anaesthesia for diagnostic or therapeutic procedures. Fourteen consecutive patients were divided at random into two groups: Group P received propofol and Group C (control) received only Intralipid 10%; an additional group of six patients received i.v. flunitrazepam (0.03 mg · kg^-1). Lung mechanics (dynamic and static compliance, peak inspiratory pressure, intrinsic positive and expiratory pressure, minimal and maximal resistances of the respiratory system) were evaluated in basal conditions and 3 and 6 min after propofol, Intralipid or flunitrazepam administration. We did not observe significant variations of the evaluated variables after Intralipid or flunitrazepam (Groups C and F), while in patients who received propofol (Group P), we observed the following modifications: dynamic compliance increased from 2.3 ± 0.3 to 2.8 ± 0.4 ml · kPa^-1 (P<0.05), peak inspiratory pressure decreased from 3.3 ± 0.7 to 2.8 ± 0.4 kPa (P <0.05), minimal resistances of the respiratory system (that mainly reflect airways resistances) decreased from 1 ± 0.2 to 0.7 ± 0.2 kPa · 1^-1 · s^-1 (P <0.01). Our results suggest that propofol induces bronchodilation in mechanically ventilated COPD patients, and that this effect is not related specifically to the induction of general anesthesia.     

Assessment of volume responsiveness in mechanically ventilated patients

Monitoring and management of intravascular volume status is of crucial importance in critically ill patients. Hypovolemia, induced by hemorrhage or pathologic fluid shifts in the presence of systemic inflammation, is frequently the cause for hemodynamic instability and hypotension. This deficit of central blood volume leads to a reduction in biventricular cardiac preload. With respect to the Frank-Starling mechanism, this causes an alteration in left ventricular stroke volume. If this reduction in stroke volume cannot be compensated by an increase in heart rate, this finally results in a decline of cardiac output. In this clinical situation fluid loading is the treatment of choice. However, insufficient peripheral vascular resistance and thus reduced cardiac afterload as well as impaired myocardial contractility also have to be taken in account to be causative for hypotension. Potential hazards of fluid loading specifically in the latter situation include pulmonary edema, worsening of pulmonary gas exchange and myocardial failure. Thus, prediction of fluid responsiveness, i.e. the prediction of the hemodynamic response to fluid loading is of utmost importance in critically ill patients. Several conventional parameters of systemic hemodynamic monitoring such as the cardiac filling pressures CVP and PAOP, the estimation of the left ventricular end-diastolic area (LVEDA) by echocardiography and measurement of central blood volumes as the right-ventricular end-diastolic volume (RVEDV) or the global end-diastolic volume (GEDV) by thermodilution are frequently used for preload monitoring. Further, functional preload parameters such as the left ventricular stroke volume variation (SW), describing the specific interactions of the heart and the lungs under mechanical ventilation, have been recently proposed to be useful for predicting fluid responsiveness. Thus, it is the aim of the present article to analyze these different concepts of hemodynamic monitoring regarding their usefulness and clinical applicability to predict fluid responsiveness at the bedside.     

机械通气患者口腔护理效果研究

目的了解机械通气患者口腔护理效果。方法采用便利抽样法选取某三级甲等医院ICU收治的47例机械通气患者,常规口腔护理后检测中切牙、侧切牙、尖牙及第一前磨牙共16颗牙邻面及颈部残留牙菌斑量。结果经口腔护理后,47例患者被检牙均残留不同程度牙菌斑,其中,牙邻面菌斑残留量显著多于牙颈部;随牙位后移,各部位菌斑量显著增加(均P<0.05)。不同象限同一牙位菌斑残留量差异无统计学意义(均P>0.05)。结论现行口腔护理方法清除牙菌斑效果不理想,尤其是后牙远中邻面菌斑清除困难,有待改良护理技术以提高口腔护理质量。     

Gastric intramural pH in mechanically ventilated patients.

BACKGROUND: The hypothesis that gastric intramural pH (pHi) is predictive of outcome in haemodynamically stable, mechanically ventilated patients was tested in 25 patients on assisted mechanical ventilation for respiratory failure. METHODS: Simultaneous samples of arterial blood and gastric juice were obtained from patients on assist control, synchronised intermittent and pressure control ventilation during the first 48 hours of mechanical ventilation. Gastric pHi was calculated from the equation: pHi= 6.1 + log HCO3/(gastric PCO2 X 0.03). The outcome was survival or death due to respiratory or circulatory failure within 45 days of admission. RESULTS: Gastric pHi proved to be a better predictor of outcome than all presently utilised parameters. Although all patients included in this study were haemodynamically stable and were similar for all laboratory indices, the only variable capable of accurately predicting outcome was gastric pHi. Patients with a normal arterial pH but a gastric intramural pH of less than 7.25 had an observed mortality of 66%. Standard severity of illness scores grossly underestimated mortality rates. The sensitivity and specificity of a gastric pHi value of less than 7.25 in predicting death were 86% and 83%, respectively. A receiver operator curve for all variables exaggerates the superiority of gastric pHi as a predictor of outcome. CONCLUSION: Low gastric pHi, a marker of gastrointestinal ischaemia, may occur in the presence of normal haemodynamics and may be used to predict severity of illness and mortality accurately.     

Analgesia and sedation of mechanically ventilated critical patients

Provision of adequate analgesia and sedation is an essential element in the overall management of critically ill patients who require mechanical ventilation. Familiarity with the regimens used for the different sedatives and analgesic drugs and awareness of their pharmacodynamics and pharmacokinetics in the context of each patient are essential for provision of the most appropriate treatment. In this article, we review assessment methods, the most recent therapeutic recommendations, and a range of analgesic and sedative drugs.     

Clinical evaluation of a continuous oxygen consumption monitor in mechanically ventilated patients

We measured oxygen consumption using a new noninvasive modular metabolic monitor, M-COVX trade mark, in ventilated critically ill patients. Oxygen consumption was measured continuously as part of routine monitoring for up to 24 h following mechanical ventilation in 27 patients admitted to a general intensive care unit. We explored several possible sources of error. Most errors related to inaccurate tidal volume measurement, which resulted in rejection of a median 14% (interquartile range 8-34%) of data. Water accumulation in the pneumotachograph was responsible and occurred more frequently with water bath humidifiers. After manual removal of erroneous data mean oxygen consumption values were virtually identical to calculated values in 24 of 27 patients. We conclude that in most ventilated patients averaging of continuous oxygen consumption data with the M-COVX module results in small errors.     

Occult acetabular fractures in elderly patients: a report of three cases

Three elderly patients with acetabular fractures not evident on the initial plain radiographs are presented. All had a fall and were unable to bear weight. Cross-sectional imaging and repeated plain radiography confirmed fractures of the acetabulum. Occult acetabular fractures may occur in elderly patients after a fall and present with persistent discomfort and difficulty walking. When there is reason to suspect such a fracture, further diagnostic studies, including a Judet view radiograph, bone scan, computed tomographic scan or magnetic resonance image should be performed.     

Risk factors for intra-abdominal hypertension in mechanically ventilated patients

Background: Intra‐abdominal hypertension (IAH) in intensive care patients is associated with an adverse outcome, but the risk factors for development of IAH have not been extensively studied. We aimed to identify independent risk factors for IAH in mechanically ventilated (MV) patients. Methods: In this prospective observational study, 563 MV patients staying in the general intensive care unit (ICU) of a university hospital for more than 24 h were observed during their ICU stay. Repeated intermittent measurements of intra‐abdominal pressure (IAP) via the urinary bladder were performed. Results: IAH (sustained or repeated IAP≥12 mmHg) developed in 182 patients (32.3%). From all the study patients, 44.4% had a primary pathology in the abdomino‐pelvic region. Two thirds of all IAH cases developed in this group. Obesity [body mass index (BMI)>30], high positive end‐expiratory pressure (PEEP>10), respiratory failure (PaO₂/FiO₂ <300), use of vasopressors/inotropes, pancreatitis, hepatic failure/cirrhosis with ascites, gastrointestinal bleeding and laparotomy on admission day were identified as independent risk factors for IAH. None of the patients without any of these risk factors (26 patients) developed IAH. Conclusion: The precise prediction of development IAH in mixed ICU population remains difficult. In the absence of BMI>30, PEEP>10 cmH₂O, PaO₂/FiO₂ <300, use of vasopressors/inotropes, pancreatitis, hepatic failure/cirrhosis with ascites, gastrointestinal bleeding and laparotomy on admission day, the risk for development of IAH in MV ICU patients is minimal.     

Assessment of fluid responsiveness in mechanically ventilated cardiac surgical patients

BACKGROUND AND OBJECTIVE: Accurate assessment of preload responsiveness is an important goal of the clinician to avoid deleterious volume replacement associated with increased morbidity and mortality in mechanically ventilated patients. This study was designed to evaluate the accuracy of simultaneously assessed stroke volume variation and pulse pressure variation using an improved algorithm for pulse contour analysis (PiCCO plus, V 5.2.2), compared to the respiratory changes in transoesophageal echo-derived aortic blood velocity (deltaVpeak), intrathoracic blood volume index, central venous pressure and pulmonary capillary wedge pressure to predict the response of stroke volume index to volume replacement in normoventilated cardiac surgical patients. METHODS: We studied 20 patients undergoing elective coronary artery bypass grafting. After induction of anaesthesia, haemodynamic measurements were performed before and after volume replacement by infusion of 6% hydroxyethyl starch 200/0.5 (7 mL kg(-1) ) with a rate of 1 mL kg(-1) min(-1). RESULTS: Baseline stroke volume variation correlated significantly with changes in stroke volume index (deltaSVI) (r2 = 0.66; P < 0.05) as did baseline pulse pressure variation (r2 = 0.65; P < 0.05), whereas baseline values of deltaVpeak, intrathoracic blood volume index, central venous pressure and pulmonary artery wedge pressure showed no correlation to deltaSVI. Pulse contour analysis underestimated the volume-induced increase in cardiac index measured by transpulmonary thermodilution (P < 0.05). CONCLUSIONS: The results of our study suggest that stroke volume variation and its surrogate pulse pressure variation derived from pulse contour analysis using an improved algorithm can serve as indicators of fluid responsiveness in normoventilated cardiac surgical patients. Whenever changes in systemic vascular resistance are expected, the PiCCO plus system should be recalibrated.     

Thymolipoma: a report of three cases

Three cases of thymolipoma, seen in a 6 year old boy, a 34 year old woman and a 24 year old man are presented herein. The weight of each tumor was 1380 g, 670 g and 560 g respectively. The 2 male patients had no symptoms and the woman only complained of a fever. On CT scan the thymic tissue was recognized as islands of soft tissue density within a fatty mass, and T1 weighted MRI was helpful in demonstrating the predominant fatty nature of this tumor. Thus, our experience demonstrates that CT and MRI are valuable for establishing a diagnosis of thymolipoma. In a review of the literature on the subject, some clinical features of this non-malignant tumor in the mediastinum are discussed. Although rare, thymolipoma should be considered in the differential diagnosis of mediastinal tumors.     

Macrostomia: a report of three cases

Transverse facial clefts (macrostomia) are rare disorders that result when the embryonic mandibular and maxillary processes of the first branchial arch fail to fuse properly to form the corners of the mouth. Macrostomia may be seen alone or in association with other anomalies. It may be unilateral, extending along a line from the commissure to the tragus. It is usually partial, but rarely complete. Transverse facial clefts are more common in males, and commoner on the left when unilateral. We report on 3 patients with macrostomia managed in our unit. There were 2 girls with a bilateral transverse facial cleft and a boy with a left unilateral transverse facial cleft. All had a 3 layered repair of their clefts with Z-plasty repair of the skin. The longest duration of follow-up was 2 weeks. Strict adherence to the principles of surgical reconstruction is advised in the repair of macrostomia to prevent a poor treatment outcome.     

Specific cardiomyopathy in lupus patients: report of three cases

Clinically important myocarditis is an unusual feature in patients with systemic lupus erythematosus (SLE). We report three consecutive lupus patients over a 1 year period who developed severe left ventricular dysfunction in the absence of coronary artery disease or hypertensive cardiomyopathy. Two of them had clinical and biological flare of the disease whereas the lupus was quiescent in the latter. Two of them had positive IgG anticardiolipin antibodies. High dose steroids were given in two patients; one of them also required cyclophosphamide on account of diffuse proliferative glomerulonephritis. Left ventricular function improved quickly and markedly in these two patients; one of them had recurrence of severe myocarditis at intervals of 6 years and was each time responsive to steroids. Lupus cardiomyopathy, a rare event in the course of SLE, can be related to the disease even in the absence of coronary artery disease or hypertensive cardiomyopathy. It may be improved by steroids and immunosuppressive therapy. Literature concerning this cardiac manifestation in lupus is reviewed.     

Brain tissue pH in severely head-injured patients: a report of three cases

It is well established that low cerebrospinal fluid (CSF) pH and high CSF lactate concentration indicate the development of brain acidosis after severe human head injury. However, there is no direct evidence that tissue acidosis actually occurs. We measured brain extracellular pH (pHe) in three patients undergoing operation for the evacuation of acute subdural hematomas. A pH-sensitive polymer membrane electrode was inserted 500 micron into the cerebral cortex close to the damaged area. The pHe values obtained were correlated with ventricular CSF acid-based parameters and extension of the brain lesion. The CSF pH was higher than the pHe in all cases; the pHe was particularly low in areas of contusion or compression by mass lesion. The effect of focal brain tissue acidosis on clinical course after severe head injury is discussed.     

益生菌预防机械通气患者肠内营养相关性腹泻

目的观察益生菌对机械通气患者肠内营养相关性腹泻的预防作用。方法将120例机械通气患者随机分为观察组与对照组各60例。观察组在胃肠内注入瑞能肠内营养剂加益力多,对照组常规加入瑞能肠内营养剂,观察两组患者7d内腹泻的发生率及粪便球杆比值。结果观察组患者腹泻发生率为10.0%,对照组为36.7%,两组比较,差异有统计学意义(P0.01);粪便细菌油镜观察两组球杆比值比较,差异有统计学意义(P0.01)。结论益生菌可以帮助恢复失衡的肠道微生态,有效预防机械通气患者胃肠内营养过程中腹泻的发生,有利于肠内营养治疗的顺利进行。     

Expiratory flow limitation in morbidly obese postoperative mechanically ventilated patients

Although obesity promotes tidal expiratory flow limitation (EFL), with concurrent dynamic hyperinflation (DH), intrinsic PEEP (PEEPi) and risk of low lung volume injury, the prevalence and magnitude of EFL, DH and PEEPi have not yet been studied in mechanically ventilated morbidly obese subjects. In 15 postoperative mechanically ventilated morbidly obese subjects, we assessed the prevalence of EFL [using the negative expiratory pressure (NEP) technique], PEEPi, DH, respiratory mechanics, arterial oxygenation and PEEPi inequality index as well as the levels of PEEP required to abolish EFL. In supine position at zero PEEP, 10 patients exhibited EFL with a significantly higher PEEPi and DH and a significantly lower PEEPi inequality index than found in the five non-EFL (NEFL) subjects. Impaired gas exchange was found in all cases without significant differences between the EFL and NEFL subjects. Application of 7.5 +/- 2.5 cm H2O of PEEP (range: 4-16) abolished EFL with a reduction of PEEPi and DH and an increase in FRC and the PEEPi inequality index but no significant effect on gas exchange. The present study indicates that: (a) on zero PEEP, EFL is present in most postoperative mechanically ventilated morbidly obese subjects; (b) EFL (and concurrent risk of low lung volume injury) is abolished with appropriate levels of PEEP; and (c) impaired gas exchange is common in these patients, probably mainly due to atelectasis.     

重症病房机械通气病人的镇静

镇静是处理机械通气危重病人的重要组成部分.在提供充分的镇痛和去除了可逆的诱因后,适度镇静可以减轻病人的焦虑烦躁、增加人机顺应性,保证病人的安全舒适.推荐使用镇静评分表定期进行评估和每天中断镇静评价病人的神经功能、自主呼吸能力.     

Guidelines for weaning from positive end-expiratory pressure in ventilated patients

Positive end-expiratory pressure is helpful in avoiding hypoxemia but can cause barotrauma to the lungs and heart. Reducing positive end-expiratory pressure as quickly as possible without sacrificing oxygenation is desirable. Weaning from positive end-expiratory pressure is an integral part of removing mechanical ventilation, but the selection of patients for positive end-expiratory pressure reduction and appropriate monitoring after this has not been established. We prospectively studied 29 positive end-expiratory pressure weaning trials to document oxygenation changes. Patients had stable vital signs and were not septic. All were receiving inspired oxygen concentrations of 50 percent or less and 5 to 12 cm H2O of positive end-expiratory pressure. Positive end-expiratory pressure was decreased by 2 cm H2O increments. Arterial blood gas levels were monitored at 1, 3, 5, and 30 minutes and at 1, 2, 4, and 6 hours after positive end-expiratory pressure reduction. Positive end-expiratory pressure reduction was successful if the partial pressure of oxygen value did not decrease below 65 mm Hg. Patients were successfully weaned from positive end-expiratory pressure in 27 of 29 trials (93 percent). The partial pressure of oxygen nadir occurred at 30 minutes. In successful trials, the partial pressure of oxygen value decreased an average of 12 mm Hg, an average change of -8 percent from the baseline partial pressure of oxygen value. This returned to baseline within 6 hours in only 13 patients (48 percent). The two patients in whom weaning failed had clinical signs of hypoxemia at 30 minutes. Their changes in partial pressure of oxygen at 30 minutes averaged -44 mm Hg (a 41 percent decrease). These data outline an approach to positive end-expiratory pressure weaning which is easy and practical. It supports oxygenation with the least physiologic embarrassment to the patient. In our patients it was 100 percent predictive of success.