Changes in pulmonary mechanics after fiberoptic bronchoalveolar lavage in mechanically ventilated patients

Objective: We prospectively assessed the impact of bronchoalveolar lavage (BAL) on respiratory mechanics in critically ill, mechanically ventilated patients. Study design: Mechanically ventilated patients underwent BAL of one lung segment using 5 × 20 ml of sterile, physiologic saline with a temperature of 25–28 °C. The fractional inspired oxygen was increased to 1.0, but ventilator settings were otherwise left unchanged. Static pulmonary compliance, pulmonary resistance, alveolar ventilation, and serial dead space were measured 60 min and 2 min before and 8, 60, and 180 min after BAL to assess the consequences of the procedure. In addition, blood gases [partial pressure of carbon dioxide in arterial blood (PaCO₂) and arterial oxigen tension (PaO₂)], hemodynamic variables (heart rate, systolic and diastolic blood pressure), and body temperature were recorded at the same time points. Setting: Intensive care unit of a university hospital. Patients: 18 consecutive critically ill, mechanically ventilated patients. Results: Pulmonary compliance decreased by 23 % (p < 0.05) and pulmonary resistance increased by 22 % (p < 0.05) shortly after BAL. The changes in pulmonary compliance and resistance were more than 30 % in one third of the patient population. One hour after the procedure, PaO₂ was significantly lower and PaCO₂ significantly higher than before the procedure. Three hours after the procedure, pulmonary resistance returned to pre-BAL values but compliance remained 10 % below baseline values (p < 0.05). Conclusion: BAL in mechanically ventilated patients is associated with deterioration of pulmonary mechanics and function. Received: 19 January 1998 Accepted: 20 August 1998     

Erythropoietin response in critically ill mechanically ventilated patients: a prospective observational study

Introduction

Anemia is a common problem in critically ill patients. The etiology of anemia of critical illness is often determined to be multifactorial in the clinical setting, but the pathophysiology remains to be elucidated. Erythropoietin (EPO) is an endogenous glycoprotein hormone that serves as the primary stimulus for erythropoiesis. Recent evidence has demonstrated a blunted EPO response as a factor contributing to anemia of critical illness in specific subsets of patients. Critically ill patients requiring mechanical ventilation who exhibit anemia have not been the subject of previous studies. Our goal was to evaluate the erythropoietic response to anemia in the critically ill mechanically ventilated patient.

Methods

A prospective observational study was undertaken in the medical intensive care unit of a tertiary care, military hospital. Twenty patients admitted to the medical intensive care unit requiring mechanical ventilation for at least 72 hours were enrolled as study patients. EPO levels and complete blood count were measured 72 hours after admission and initiation of mechanical ventilation. Admission clinical and demographic data were recorded, and patients were followed for the duration of mechanical ventilation. Twenty patients diagnosed with iron deficiency anemia in the outpatient setting were enrolled as a control population. Control patients had baseline complete blood count and iron panel recorded by primary care physicians. EPO levels were measured at the time of enrollment in conjunction with complete blood count.

Results

The mean EPO level for the control population was 60.9 mU/ml. The mean EPO level in the mechanically ventilated patient group was 28.7 mU/ml, which was significantly less than in the control group (P = 0.035). The mean hemoglobin value was not significantly different between groups (10.6 g/dl in mechanically ventilated patients versus 10.2 g/dl in control patients; P > 0.05).

Conclusion

Mechanically ventilated patients demonstrate a blunted EPO response to anemia. Further study of therapies directed at treating anemia of critical illness and evaluating its potential impact on mechanical ventilation outcomes and mortality is warranted.

     

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: A prospective,randomized trial

Objective Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequency flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a randomized study.Design Preterm babies weighing 1800g suffering from RDS and ventilated by conventional mechanical ventilation (CMV) were randomized to be further ventilated either by CMV (group CMV) or by HFFIV (group HFFIV) when peak inspiratory pressure (PIP) on CMV was 20cmH₂O.Setting The study was undertaken in the neonatal intensive care unit of the Erasmus Hospital.Patients 24 patients entered into the investigation and were randomized but 2 patients were removed from the study because the switch over to HFFIV failed. Eight of the 12 CMV patients and 5 of the 10 HFFIV patients completed the study.Measurements and results Clinical variables, blood gas analysis and ventilatory variables were looked at. There were no differences in mortality, in incidence of air leaks and pulmonary complications or in blood gas analysis. Bronchopulmonary dysplasia was not decreased by the use of HFFIV.Conclusion It is concluded that HFFIV is safe although it offers no concrete advantages over CMV when applied as we did in a low pressure approach.     

Cytomegalovirus infection in critically ill patients: a systematic review

Introduction

The precise role of cytomegalovirus (CMV) infection in contributing to outcomes in critically ill immunocompetent patients has not been fully defined.

Methods

Studies in which critically ill immunocompetent adults were monitored for CMV infection in the intensive care unit (ICU) were reviewed.

Results

CMV infection occurs in 0 to 36% of critically ill patients, mostly between 4 and 12 days after ICU admission. Potential risk factors for CMV infection include sepsis, requirement of mechanical ventilation, and transfusions. Prolonged mechanical ventilation (21 to 39 days vs. 13 to 24 days) and duration of ICU stay (33 to 69 days vs. 22 to 48 days) correlated significantly with a higher risk of CMV infection. Mortality rates in patients with CMV infection were higher in some but not all studies. Whether CMV produces febrile syndrome or end-organ disease directly in these patients is not known.

Conclusions

CMV infection frequently occurs in critically ill immunocompetent patients and may be associated with poor outcomes. Further studies are warranted to identify subsets of patients who are likely to develop CMV infection and to determine the impact of antiviral agents on clinically meaningful outcomes in these patients.     

Comparison of A-mode ultrasound and computed tomography: Detection of secretion in maxillary and frontal sinuses in ventilated patients

Objective To study the accuracy of A-mode ultrasonography (A-MU) in detecting secretion in maxillary and frontal sinuses in critically ill, intubated patients undergoing mechanical ventilation.Design Open study in mechanically ventilated, comatose patients.Setting Medical-surgical intensive care unit in the General Hospital of Rovigo.Patients 50 consecutive, mechanically ventilated, critically ill patients. All patients were in a coma and needed cerebral computed tomography (CT) for a diagnosis.Measurements and results The A-MU technique gave 100 images of maxillary and frontal sinuses. The images were read blindly and classified into five categories: definitely normal, definitely abnormal, probably normal, questionable, and probably abnormal. CT findings were considered to be the gold standard. The specificity of echo images varied from 72 to 98% and the sensitivity from 63 to 86% for maxillary sinuses. For frontal sinuses, the specificity varied from 96 to 99% and the sensitivity from 14 to 57%. The area under the receiver-operating characteristic curve was found to be 0.89 and 0.76 for maxillary and frontal sinuses, respectively.Conclusions The A-MU technique is an accurate tool for detecting secretion in the maxillary sinuses in intubated patients. More investigations are necessary in order to evaluate its usefulness in the frontal sinuses.The work was done at the General Hospital, Rovigo, Italy     

Paralysis has no effect on chest wall and respiratory system mechanics of mechanically ventilated,sedated patients

Objective To evaluate the separate effects of sedation and paralysis on chest wall and respiratory system mechanics of mechanically ventilated, critically ill patients.Setting: ICU of the University La Sapienza Hospital, Rome.Patients and participants 13 critically ill patients were enrolled in this study. All were affected by disease involving both lungs and chest wall mechanics (ARDS in 4 patients, closed chest trauma without flail chest in 4 patients, cardiogenic pulmonary oedema with fluidic overload in 5 patients).Measurements and results Respiratory system and chest wall mechanics were evaluated during constant flow controlled mechanical ventilation in basal conditions (i. e. with the patients under apnoic sedation) and after paralysis with pancuronium bromide. In details, we simultaneously recorded airflow, tracheal pressure, esophageal pressure and tidal volume; with the end-inspiratory and end-expiratory airway occlusion technique we could evaluate respiratory system and chest wall elastance and resistances. Lung mechanics was evaluated by subtracting chest wall from respiratory system data. All data obtained in basal conditions (with the patients sedated with thiopental or propofol) and after muscle paralysis were compared using the Student'st test for paired data. The administration of pancuronium bromide to sedated patients induced a complete muscle paralysis without producing significant modification both to the viscoelastic and to the resistive parameters of chest wall and respiratory system.Conclusions This study demonstrates the lack of additive effects of muscle paralysis in mechanically ventilated, sedated patients. Also in view of the possible side effects of muscle paralysis, our results question the usefulness of generalyzed administration of neuromuscular blocking drugs in mechanically ventilated patients.     

功能残气量在重症患者中的应用进展

功能残气量（FRC）是平静呼气末肺内残留的气体量,具有重要的生理功能。在需要机械通气的重症患者中呼气结束时的肺容积被称为呼气末肺容积。目前临床上有多种检测和监测FRC的方法,包括CT测量法、氦气稀释法、氮气冲洗法、电阻抗断层成像技术等方法,其中氮气冲洗法中的氮气洗入/洗出技术更适合在重症患者中开展。FRC可以作为评估机械通气患者肺部疾病病情并指导个性化的保护性机械通气策略的方法,来降低呼吸机相关性肺损伤（VILI）。FRC在机械通气患者中的临床应用越来越受到重视,在病情评估、ARDS患者中的肺保护通气设置和麻醉时肺部情况监测等方面具有重要临床意义。本文对FRC的病理生理功能、检测方法及在重症患者中的应用进行综述。     

Positive and negative effects of mechanical ventilation on sleep in the ICU: a review with clinical recommendations

Purpose

Sleep is an essential physiologic process that helps to restore normal body homeostasis. Sleep disturbances have been shown to be associated with poor clinical outcomes, such as a greater risk of cardiovascular disease and increasing mortality. Critically ill patients, particularly those receiving mechanical ventilation, may be more susceptible to sleep disruption.

Methods and Results

Mechanical ventilation is an important factor influencing sleep in critically ill patients as it may have positive or negative effects, depending on patient population, mode, and specific settings. Other causes of sleep disruption include the acute illness itself, the daily routine care, and the effects of medications. Improving sleep in patients admitted to an intensive care unit has the potential to improve both short- and long-term clinical outcomes. In this article we review the specific aspects of sleep in critically ill mechanically ventilated patients, including abnormal sleep patterns and loss of circadian rhythm, as well as the effects of mechanical ventilation and intravenous sedatives on sleep quality and quantity.

Conclusions

We provide recommendations for clinicians regarding optimal ventilatory settings and discuss fields for future research.

     

危重机械通气患者PICCO监护的护理体会

本文阐述了对30例应用PICCO进行血流动力学监测的危重机械通气患者给予恰当护理后取得良好的临床疗效,还未出现感染、出血、栓塞等并发症及无意外堵管、拔管的发生;归纳和总结了如何护理及正确测量PICCO数值和预防并发症的发生,尤其是对危重机械通气患者,为相关护理人员的临床实践和科研作一参考。     

Cytomegalovirus colitis in intensive care unit patients: Difficulties in clinical diagnosis

Purpose

Cytomegalovirus (CMV) infection occurs increasingly in critically ill patients in intensive care units (ICUs). We reported CMV colitis which has rarely been recognized in the ICU patients.

Methods

CMV DNA was detected by polymerase chain reaction (PCR) for blood and/or stool samples. Definite diagnosis of CMV colitis required histopathology or CMV immunohistochemical staining of colorectal biopsies. We reviewed ICU patients characterized by positive blood or stool CMV-PCR with colorectal bleeding or water diarrhea.

Results

We identified 18 patients (biopsy-proved, n = 8; probable cases, n = 10). The most common comorbidities were chronic renal disease, diabetes mellitus, and coronary artery disease. Stool CMV-PCR was positive in 7 of 10 patients (2 of 3 biopsy-proved and 5 of 7 probable cases). Colonoscopy was performed for 15 patients, revealing ulcerative or polypoid lesions. The endoscopists obtained colonic biopsies from 9 patients. Yet, the pathologists reported CMV colitis for 4 patients. Additional 4 patients were confirmed using immunohistochemical stain by the request of clinical physicians. Pseudomembranous colitis was found in 4 patients.

Conclusion

Diagnosis of CMV colitis seems difficult in clinical practice and need persistent communication between clinicians. The positive stool CMV-PCR result was a useful hint for adding immunohistochemical stain in mucosal biopsies to make a definite diagnosis of CMV colitis.     

Safety of research bronchoscopy in critically ill patients

Objective

Bronchoscopy and bronchoalveolar lavage (BAL) are common procedures in intensive care units; however, no contemporaneous safety and outcomes data have been reported, particularly for critically ill patients.

Design

This is a retrospective analysis of prospectively collected data from teaching hospital adult intensive care units.

Interventions

One hundred mechanically ventilated patients with severe sepsis, septic shock, acute lung injury (ALI), and/or acute respiratory distress syndrome underwent bronchoscopy with unilateral BAL. Data collected included demographics, presence of sepsis or ALI, Pao₂ to Fio₂ ratio, positive end-expiratory pressure, Acute Physiology and Chronic Health Evaluation score, Sequential Organ Failure Assessment score, and peri- or postprocedural complications.

Results

Men comprised 51% of the patients; 81% of the patients were black, and 15% were white. The mean age was 52 (SD, ± 16) years. The mean Acute Physiology and Chronic Health Evaluation score was 22 (± 7.5), whereas the median Sequential Organ Failure Assessment score was 9 (interquartile range, 5-12). Ten patients (10%) had complications during or immediately after the procedure. Hypoxemia during or immediately after the BAL was the most common complication. Ninety percent of the complications were related to transient hypoxemia, whereas bradycardia and hypotension each occurred in 1 patient. Age, female sex, and higher positive end-expiratory pressure were associated with complications.

Conclusions

Bronchoscopy with BAL in critically ill patients with sepsis and ALI is well tolerated with low risk of complications, primarily related to manageable hypoxemia.     

Pneumonies virales acquises sous ventilation mécanique

Viral infections (especially respiratory infections) are not rare in critically ill non-immunocompromised patients. Efficient and rapid virologic diagnosis tests such as polymerase chain reaction (PCR) are now widely available. Herpesviridae (herpes simplex virus and cytomegalovirus) are the most frequent viruses detected among non-immunocompromised patients admitted to the intensive care unit (ICU). However, causal relationships between detected viruses and outcomes are still debated, with a variable level of demonstration among the different viruses. The aim of this review was to assess the role of viruses in causing mechanical ventilation-acquired pneumonias in non-immunocompromised ICU adult patients. We also discuss the possible physiopathology of these viral infections, as well as the opportunity for therapeutic interventions.     

Adverse hemodynamic effects of lateral rotation during mechanical ventilation.

Turning critically ill, mechanically ventilated patients every 2 hours is a fundamental nursing intervention to reduce the negative impact of prolonged immobility from preventable pulmonary complications such as ventilator-associated pneumonia and atelectasis. Unfortunately, when coupled with positive pressure ventilation, the benefits of turning may come at the expense of cardiovascular function. Clinicians should closely monitor the hemodynamic response to turning mechanically ventilated patients, and if compromise is observed, the degree and duration of compromise may provide guidance to the appropriate intervention.     

Effects of propofol on sleep quality in mechanically ventilated critically ill patients: a physiological study

Purpose

To access the effect of propofol administration on sleep quality in critically ill patients ventilated on assisted modes.

Methods

This was a randomized crossover physiological study conducted in an adult ICU at a tertiary hospital. Two nights’ polysomnography was performed in mechanically ventilated critically ill patients with and without propofol infusion, while respiratory variables were continuously recorded. Arterial blood gasses were measured in the beginning and at the end of the study. The rate of propofol infusion was adjusted to maintain a sedation level of 3 on the Ramsay scale. Sleep architecture was analyzed manually using predetermined criteria. Patient–ventilator asynchrony was evaluated breath by breath using the flow–time and airway pressure–time waveforms.

Results

Twelve patients were studied. Respiratory variables, patient–ventilator asynchrony, and arterial blood gasses did not differ between experimental conditions. With or without propofol all patients demonstrated abnormal sleep architecture, expressed by lack of sequential progression through sleep stages and their abnormal distribution. Sleep efficiency, sleep fragmentation, and sleep stage distribution (1, 2, and slow wave) did not differ with or without propofol. Compared to without propofol, both the number of patients exhibiting REM sleep (p?=?0.02) and the percentage of REM sleep (p?=?0.04) decreased significantly with propofol.

Conclusions

In critically ill patients ventilated on assisted modes, propofol administration to achieve the recommended level of sedation suppresses the REM sleep stage and further worsens the poor sleep quality of these patients.     

膈肌超声在危重症中的临床应用

膈肌是人体最重要的呼吸肌,而脓毒症、机械通气、营养不良等因素可导致膈肌功能障碍。超声因具有安全、无创、可重复性强等优点,近几年已被广泛应用于危重症患者的诊断及治疗。膈肌超声通过对膈肌结构和功能的评估,起到预测机械通气患者撤机结果、鉴别膈肌萎缩和膈肌麻痹、判断慢性阻塞性肺病严重程度以及评估人机同步性等多种作用,可用于临床危重患者膈肌功能障碍的诊断及治疗效果评估。     

有创机械通气下治疗性支气管肺泡灌洗的安全性研究

目的:探讨急诊重症监护病房(EICU)患者在有创机械通气的条件下,应用纤维支气管镜进行支气管肺泡灌洗术(BAL)治疗操作的安全性。方法:48例EICU危重症病人均为有创机械通气患者,BAL术前、中、后分别监测呼吸机及血气分析主要参数,进行比较;并对BAL术中及术后3d内出现的并发症进行记录。结果:BAL患者吸气峰压(PIP)术前与术中比较(P<0.01);潮气量(Vt)、呼吸频率(f)术中与术前比较无明显改变(P>0.05);术中和术后个别患者出现了出血、发热、心律失常等并发症,对症处理后完全缓解,未出现气压伤等严重并发症。结论:BAL操作时呼吸机显示PIP增高,实际气道内压是下降的,呼吸机表现PIP增高是假象,因此有创机械通气下进行BAL一般不会发生气压伤。BAL在EICU危重症患者气道管理方面具有良好的效果和可靠的安全性。     

Cytomegalovirus reactivation and mortality in patients with acute respiratory distress syndrome

Purpose

Cytomegalovirus (CMV) reactivation occurs frequently in patients with the acute respiratory distress syndrome (ARDS) and has been associated with increased mortality. However, it remains unknown whether this association represents an independent risk for poor outcome. We aimed to estimate the attributable effect of CMV reactivation on mortality in immunocompetent ARDS patients.

Methods

We prospectively studied immunocompetent ARDS patients who tested seropositive for CMV and remained mechanically ventilated beyond day 4 in two tertiary intensive care units in the Netherlands from 2011 to 2013. CMV loads were determined in plasma weekly. Competing risks Cox regression was used with CMV reactivation status as a time-dependent exposure variable. Subsequently, in sensitivity analyses we adjusted for the evolution of disease severity until onset of reactivation using marginal structural modeling.

Results

Of 399 ARDS patients, 271 (68 %) were CMV seropositive and reactivation occurred in 74 (27 %) of them. After adjustment for confounding and competing risks, CMV reactivation was associated with overall increased ICU mortality (adjusted subdistribution hazard ratio (SHR) 2.74, 95 % CI 1.51–4.97), which resulted from the joint action of trends toward an increased mortality rate (direct effect; cause specific hazard ratio (HR) 1.58, 95 % CI 0.86–2.90) and a reduced successful weaning rate (indirect effect; cause specific HR 0.83, 95 % CI 0.58–1.18). These associations remained in sensitivity analyses. The population-attributable fraction of ICU mortality was 23 % (95 % CI 6–41) by day 30 (risk difference 4.4, 95 % CI 1.1–7.9).

Conclusion

CMV reactivation is independently associated with increased case fatality in immunocompetent ARDS patients who are CMV seropositive.

     

The effect of varying inspiratory flow waveforms on pulmonary mechanics in critically ill patients

Purpose: Ten mechanically ventilated patients were evaluated to determine the effect of three different inspiratory flow patterns on pulmonary mechanics. Materials and Methods: Ten consecutive mechanically ventilated critically ill patients with acute respiratory failure admitted to the intensive care unit were evaluated to assess the effects of decelerating, square, and sine waveforms on pulmonary mechanics. The variables measured were peak airway pressure (PaW), pleural pressure (Ppl), change in peak airway pressure (dPaW), inspiration time/total ventilation cycle time (Vi/Vtot), dynamic compliance (Cdyn), respiratory rate (RR), minute ventilation (Ve), and work of breathing (WOB). Results: The PaW, Ppl, and dPaW (cm H₂O) were significantly lower using the decelerating inspiratory flow waveform (P < .05) compared with sine or square waveform patterns. Ti/Ttot was also lower with the decelerating waveform (P < .05) with better dynamic compliance compared with the other waveforms (P < .10). Conclusions: These results indicate that critically ill mechanically ventilated patients show improved respiratory mechanics with decelerating inspiratory waveform that may have beneficial clinical implication. Copyright © 2000 by W.B. Saunders Company     

Assessment of diaphragmatic dysfunction in the critically ill patient with ultrasound: a systematic review

Purpose

Diaphragmatic dysfunction (DD) has a high incidence in critically ill patients and is an under-recognized cause of respiratory failure and prolonged weaning from mechanical ventilation. Among different methods to assess diaphragmatic function, diaphragm ultrasonography (DU) is noninvasive, rapid, and easy to perform at the bedside. We systematically reviewed the current literature assessing the usefulness and accuracy of DU in intensive care unit (ICU) patients.

Methods

Pubmed, Cochrane Database of Systematic Reviews, Embase, Scopus, and Google Scholar Databases were searched for pertinent studies. We included all original, peer-reviewed studies about the use of DU in ICU patients.

Results

Twenty studies including 875 patients were included in the final analysis. DU was performed with different techniques to measure diaphragmatic inspiratory excursion, thickness of diaphragm (Tdi), and thickening fraction (TF). DU is feasible, highly reproducible, and allows one to detect diaphragmatic dysfunction in critically ill patients. During weaning from mechanical ventilation and spontaneous breathing trials, both diaphragmatic excursion and diaphragmatic thickening measurements have been used to predict extubation success or failure. Optimal cutoffs ranged from 10 to 14 mm for excursion and 30–36 % for thickening fraction. During assisted mechanical ventilation, diaphragmatic thickening has been found to be an accurate index of respiratory muscles workload. Observational studies suggest DU as a reliable method to assess diaphragm atrophy in patients undergoing mechanical ventilation.

Conclusions

Current literature suggests that DU could be a useful and accurate tool to detect diaphragmatic dysfunction in critically ill patients, to predict extubation success or failure, to monitor respiratory workload, and to assess atrophy in patients who are mechanically ventilated.

     

Fentanyl as pre-emptive treatment of pain associated with turning mechanically ventilated patients: a randomized controlled feasibility study

Purpose

To compare pain incidence and changes in pain scores with fentanyl versus placebo as pre-emptive treatment during turning and 30 min post-turning in mechanically ventilated critically ill patients.

Methods

We performed a randomized, double-blind, parallel-group, placebo-controlled clinical trial in the intensive care unit of a university hospital. Seventy-five mechanically ventilated patients were randomized to an intervention group (fentanyl) or a control group (placebo). Patients in the intervention group received 1 µg/kg (medical patients) or 1.5 µg/kg (surgical patients) of fentanyl 10 min before turning. Pain indicators were assessed using the behavioral pain scale. Safety was assessed by determining the frequency and severity of pre-defined adverse events. Pain was evaluated at rest (T0), at turn start and end (T1 and T2) and at 5, 15 and 30 min post-turning (T3, T4 and T5).

Results

The two groups had similar baseline characteristics. The area under the curve for BPS values was significantly smaller in the fentanyl group than in the control group [median and interquartile range (IQR): 132 (108–150) vs. 147 (125–180); p = 0.016, respectively]. Nineteen non-serious adverse events were recorded in 14 patients, with no significant between-group differences (23 % fentanyl group vs. 14 % control group; p = 0.381).

Conclusions

These results suggest an intravenous bolus of fentanyl of 1 µg/kg for medical patients or 1.5 µg/kg for surgical patients reduces the incidence of turning-associated pain in critically ill patients on mechanical ventilation.ClinicalTrials.gov: NCT 01950000.