Current oxygen management in mechanically ventilated patients: A prospective observational cohort study

Purpose

Oxygen (O₂) is the most common therapy in mechanically ventilated patients, but targets and dose are poorly understood. We aimed to describe current O₂ administration and titration in such patients in an academic intensive care unit.

Materials and Methods

In consecutive ventilated (> 48 hours) patients we prospectively obtained fraction of inspired O₂ (Fio₂), pulse oximetry O₂ saturation (Spo₂) and arterial O₂ tension (Pao₂) every 6 hours. We calculated the amount of excess O₂ delivery and the intensivists’ response to hyperoxemia (Spo₂ > 98%).

Results

During 358 mechanical ventilation days in 51 critically ill patients, median calculated excess O₂ delivery was 3472 L per patient. Patients spent most of their time with their Spo₂ > 98% (59% [29-83]) and Pao₂ between 80 and 120 mm Hg (59% [38–72]). In addition, 50% of all observations showed hyperoxemia and 4% severe hyperoxemia (Pao₂ > 202.5 mm Hg). Moreover, 71% of the calculated total excess 263,841 L of O₂ was delivered when the Fio₂ was 0.3 to 0.5. When hyperoxemia occurred with an Fio₂ between 0.3 and 0.4, for 88% of episodes, no Fio₂ adjustments were made.

Conclusions

Excess O₂ delivery and liberal O₂ therapy were common in mechanically ventilated patients. Current O₂ therapy practice may be suboptimal and further investigations are warranted.     

Predictors of mortality of mechanically ventilated patients in internal medicine wards

Purpose

Budget restrictions have led to shortage of intensive care unit (ICU) beds in several countries. Consequently, ventilated patients are often kept on the wards. This study examined survival likelihood among patients ventilated on the wards and the predictive value of commonly used severity-of-illness scores.

Methods

This study is a prospective observation and characterization of consecutive, mechanically ventilated patients in 3 internal medicine wards of a single hospital who were denied ICU admission. Outcome measures are as follows: 28-day mortality, survival to hospital discharge, and 3 months postdischarge.

Results

Eighty-six patients were examined. The patients were 78.9 ± 8.9 years old; 53% were independent preadmission. Respiratory insufficiency due to infection was the main reason for mechanical ventilation (58%). Charlson and acute physiology scores (APS) averaged 4 ± 2.2 and 91.8 ± 26.7, respectively. Twenty-eight-day mortality was 71%, whereas in-hospital mortality was 74% and 3 months postdischarge mortality was 79%. Survivors were significantly younger than nonsurvivors (74.4 ± 8.5 years vs 80.4 ± 8.6 years, P < .01), were more likely to be ventilated for cardiac causes (41% vs 11%, P = .04), and had significantly higher initial mean blood pressure (79.4 mm Hg vs 58.2 mm Hg, P = .02) and blood albumin levels (29.8 g/L vs 25.7 g/L, P = .05). Death rate was 10 times more likely, with an APS greater than 90 on the day of intubation as compared with an APS less than 90.

Conclusion

Mortality in patients ventilated on the ward was high, especially in the subgroup of patients with an APS score greater than 90. The early calculation of APS may assist in focusing therapeutic efforts on patients with better survival chances.     

Memory in relation to depth of sedation in adult mechanically ventilated intensive care patients

Objective To investigate the relationship between memory and intensive care sedation.Design and setting Prospective cohort study over 18 months in two general intensive care units (ICUs) in district university hospitals.Patients 313 intubated mechanically ventilated adults admitted for more than 24 h, 250 of whom completed the study.Measurements Patients (n = 250) were interviewed in the ward 5 days after discharge from the ICU using the ICU Memory Tool. Patient characteristics, doses of sedative and analgesic agents, and sedation scores as measured by the Motor Activity Assessment Scale (MAAS) were collected from hospital records after the interview.Results Patients with no recall (18%) were significantly older, had higher baseline severity of illness, and experienced fewer periods of wakefulness (median proportion of MAAS score 3; 0.37 vs. 0.70) than those who had memories of the ICU (82%). Multivariate analyses showed that increasing proportion of MAAS 0–2 and older age were significantly associated with having no recall. Patients with delusional memories (34%) had significantly longer ICU stay (median 6.6 vs. 2.2 days), higher baseline severity of illness, higher proportions of MAAS scores 4–6, and more administration of midazolam than those with recall of the ICU without delusional memories.Conclusions Heavy sedation increases the risk of having no recall, and longer ICU stay increases the risk of delusional memories. The depth of sedation during total ICU stay as recorded with the MAAS may predict the probability of having memories of the ICU.     

Inhaled Dornase alfa (Pulmozyme) as a noninvasive treatment of atelectasis in mechanically ventilated patients

Background

Lobar or segmental collapse of the lung in mechanically ventilated patients is a common occurrence in the intensive care unit. Management is labor and time intensive and not highly effective.

Methods

We conducted a randomized, placebo-controlled, double-blind pilot study to determine whether nebulized Dornase alfa improves radiologic and clinical outcomes in ventilated patients with lobar atelectasis. Drug or placebo was administered twice daily until extubation, death, or transfer. The primary outcome was the total chest x-ray score: secondary outcomes of interest were oxygenation, lung compliance, and rate of extubation over the first 5 days. The groups consisted of 14 intervention patients and 16 control patients.

Results

There were no significant differences in “Total Chest X-Ray Score" or compliance over the 5 days of study. There was an improvement in oxygenation for the intervention group at day 5 (P = .03). In addition, this group was less likely to remain intubated over the first 24 hours of the study, a difference that did not persist over the course of the study.

Conclusions

Dornase alfa does not improve the appearance of atelectasis on chest radiographs, or the “Total Chest X-Ray Score" over the first 5 days of treatment in mechanically ventilated patients. The intervention group's higher rate of extubation during the first 24 hours as well as its improved oxygenation on day 5 were likely chance findings given the multiple potential confounders for extubation and low study power.     

The epidemiology of acute respiratory failure in hospitalized patients: a Brazilian prospective cohort study

Purpose

The purpose of this study was to assess risk factors associated with the development of acute respiratory failure (ARF) and death in a general intensive care unit (ICU).

Materials and Methods

Adults who were hospitalized at 12 surgical and nonsurgical ICUs were prospectively followed up. Multivariable analyses were realized to determine the risk factors for ARF and point out the prognostic factors for mortality in these patients.

Results

A total of 1732 patients were evaluated, with an ARF prevalence of 57%. Of the 889 patients who were admitted without ARF, 141 (16%) developed this syndrome in the ICU. The independent risk factors for developing ARF were 64 years of age or older, longer time between hospital and ICU admission, unscheduled surgical or clinical reason for ICU admission, and severity of illness. Of the 984 patients with ARF, 475 (48%) died during the ICU stay. Independent prognostic factors for death were age older than 64 years, time between hospital and ICU admission of more than 4 days, history of hematologic malignancy or AIDS, the development of ARF in ICU, acute lung injury, and severity of illness.

Conclusions

Acute respiratory failure represents a large percentage of all ICU patients, and the high mortality is related to some preventable factors such as the time to ICU admission.     

Nasogastric tube placement under sonographic observation: A comparison study of ultrasound and chest radiography in mechanically ventilated patients

BackgroundNasogastric tube insertion in the intensive care setting is common. Placement verification is required to avoid complications of bronchotracheal misplacement that range from aspiration of infused contents to death from associated causes. The gold standard of practice is chest radiography. Ultrasound is a growing modality and is readily available in most intensive care units.ObjectiveThe objective of this study was to examine the diagnostic accuracy of ultrasound imaging of nasogastric tube placements by nonradiologists compared with chest radiography in mechanically ventilated patients.MethodsThis is a dual-centre prospective, single-blind study. Correct placement was captured with a hyperechoic ultrasound image of a nasogastric tube in the oesophagus and epigastrium, which was compared with chest radiography. Patient enrolment included general adult intensive care unit admissions who were mechanically ventilated and required a nasogastric tube for either the treatment or monitoring of their illness.ResultsA total of 25 patients were enrolled (15 men, 10 women), and their mean age was 68.1 ± 13.8 years. Outcome measures were the percentage of correctly identified nasogastric tubes in the oesophagus and epigastrium. The sensitivity of oesophagus ultrasound was 88%, and the positive predictive value was 100%. The subxiphoid sensitivity was 64%, and the positive predictive value was 100%. Comparison sensitivity and specificity of oesophagus versus subxiphoid ultrasound was 64% and 33%, respectively. There was a positive predictive value of 88% and a negative predictive value of 11%. The results showed a variance in detection sensitivity in the ultrasound scans of the oesophagus (0.88) and subxiphoid (0.64) (N = 25, p = 0.012).ConclusionNasogastric tube placement verification via ultrasound in critically ill mechanically ventilated patients conducted by nonradiologists with minimal training is associated with diagnostic accuracy. These results add to the limited evidence in the current literature; however, they should be considered with awareness that placement in the stomach in this study was detected in 64% of cases, alongside the missed captured evidence of the sonographer's ability to identify misplacement.     

机械通气患者贫血的临床观察研究

目的 观察贫血对机械通气患者预后的影响.方法 采用前瞻性研究方法,收集入住重症监护病房(ICU)预计机械通气时间≥72 h,血红蛋白(Hb)浓度≥100 g/L的患者.根据患者机械通气第3日的Hb浓度分为贫血组和非贫血组.比较两组患者1、3、7d血清促红细胞生成素(EPO)、Fe3+、转铁蛋白(TRF)水平,14 d 内人均输血量,3、7、14 d内人均日采血量以及机械通气时间、28 d脱机存活率、住院时间和28 d病死率.结果 共入选40例患者,贫血组18例,非贫血组22例.与非贫血组比较,贫血组患者血清Fe3+较低,血清EPO、TRF较高;贫血组患者14 d内人均输血量(U)较多[4.0(2.0,6.0)比2.0 (0.0,2.0),P＜0.01],ICU病死率较高(44.4％比13.6％,P＜0.05),住院时间(d)较长[35.0( 16.5,51.6)比24.5( 10.0,35.8),P＜ 0.05 ],28 d脱机存活率较低(44.4％比72.7％,P＜ 0.05).而贫血组和非贫血组机械通气时间(d:18.3±10.8比11.6±8.2,P＞0.05)、ICU住院时间[d:16.5(8.0,21.5)比11.0(5.8,18.3),P＞0.05]和住院病死率(61.1％比31.8％,P＞0.05)比较差异无统计学意义.结论 贫血患者机械通气时间及住院时间较长,ICU病死率较高,28 d脱机存活率较低.     

Delirium in patients admitted to a step-down unit: Analysis of incidence and risk factors

Background

Delirium is a rather common complication among patients admitted in intensive care units (ICUs), and rather than a single entity, it can be considered a spectrum of diseases where, besides overt cases, there are also many subsyndromal forms. Although there are many data about ICU delirium, there are few data concerning this complication in patients transferred from the ICU to a step-down unit (SDU) once clinically stable.

Objectives

With the present study, we wanted to assess the incidence of and risk factors for delirium and subsyndromal forms and their impact on clinical outcome in a group of patients transferred from an ICU to an SDU.

Methods

All patients transferred from an ICU to our SDU over a 2-year period were screened for delirium and subsyndromal delirious forms using the Intensive Care Delirium Screening Checklist, a simple tool already validated in the ICU. The following data were also recorded: demographic data, severity score (SAPS II), reason for admission to the SDU, length of stay, death rate, use of sedatives, impact of delirium on weaning from mechanical ventilation (MV).

Results

Among the 234 patients, the incidence of delirium and subsyndromal forms was 7.6% and 20%, respectively. Subsyndromal forms diagnosed at admission represented a risk factor for the subsequent development of delirium (odds ratio [OR], P < .0001). A previous episode of brain failure during ICU stay and older age were risks factors for the development of subsyndromal forms, whereas not needing MV was a protective factor. Delirium significantly prolonged the stay in the SDU but did not influence survival and the process of weaning from MV. Overall, the percentage of patients with an abnormal Intensive Care Delirium Screening Checklist score at discharge (5%) was reduced compared with that recorded at admission (18%).

Conclusions

Delirium may still occur after discharge from an ICU in patients who are transferred to an SDU. The strategy of care adopted in the SDU seems to positively affect the recovery from a delirious state. Patients with subsyndromal forms should be promptly recognized and treated because of the risk of developing delirium. Weaning from MV is not hindered by delirium.     

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     

集束干预策略应用于机械通气镇痛镇静患者的效果评价

目的评价机械通气(mechanical ventilation,MV)患者在镇痛镇静治疗期间应用集束干预策略的效果。方法按入科顺序编号将2011年1～10月ICU收治的108例MV患者分为2组,单号为干预组(n=57),在常规镇痛镇静护理的同时,应用集束干预策略,包括每日镇静中的唤醒、呼吸同步、镇静和镇痛药物的选择或应用、谵妄的监测和处理、早期运动和锻炼。双号为对照组(n=51),采用常规镇痛镇静护理,以及意识水平、镇痛镇静程度及脏器功能的评估监测等;比较两组患者的镇痛镇静药物使用剂量、机械通气时间、ICU治疗时间、总住院日、谵妄发生率及28d生存率。结果干预组患者镇痛镇静药物的使用剂量、机械通气时间、ICU治疗时间、总住院日与对照组相比,差异有统计学意义(P<0.001);干预组谵妄发生率低于对照组,差异有统计学意义(P<0.05)。结论集束干预策略较常规镇痛镇静护理能使MV患者取得较好的临床效果。     

机械通气治疗策略变化的单中心研究

目的 观察一个单医疗中心机械通气(MV)治疗策略的变化。方法 调查1994年1月至1997年12月（对照组）以及2004年1月至2006年12月（研究组）两个时间段人住首都医科大学附属复兴医院重症监护病房(ICU)且行MV超过24 h的502例患者的临床资料。收集的主要数据包括MV的病因、MV模式、呼吸机治疗参数、脱机方法及患者的预后。结果 ICU中MV使用率为46.1％(502/1 090),其中对照组48.9％(184/376),研究组44.5％(318/714)。502例患者中接受MV的主要原因为：肺炎18.3％（92例）,慢性阻塞性肺疾病急性加重(AECOPD) 16.3％ (82例),昏迷14.1％（71例）,术后13.7％（69例）,急性呼吸窘迫综合征(ARDS)12.7％（64例）。初始设定MV模式：对照组59.8％(110/184)为辅助/控制通气(A/C),20.7％(38/184)为压力支持通气(PSV);研究组23.0％(73/318)为A/C,57.2％(182/318)为PSV,两组差异有统计学意义(均P＜0.01);研究组无创正压通气(NPPV)的使用率较对照组明显增加[10.4％(33/318)比3.8％(7/184),P＜0.01];两组患者压力支持(PS)的平均值均为14 cmH2O(1 cmH2O=0.098 kPa),呼气末正压(PEEP)平均值均为5.0cm H2O;与对照组比较,研究组中ARDS患者PEEP水平(cm H2O)明显升高(8．0比6.0,P＜0.01),潮气量(VT,ml)明显减小(400比550,P＜0.01)。两组常用脱机方法为T管、T管+PSV、PSV3种,与对照组比较,研究组T管的使用明显增加[84.4％(184/218)比35.1％(40/114),P＜0.01],PSV使用明显减少[2.8％(6/218)比29.8％(34/114),P＜0.01]。两组MV患者的总体ICU病死率为49.6％(249/502),校正后研究组与对照组的ICU病死率比较差异无统计学意义（54.6％比55.4％,P=0.887）。结论 单中心MV治疗策略10年来发生了一些明显的变化。推测这些治疗策略的改变在一定程度上学习和借鉴了近年来发表的多中心随机对照试验(RCT)研究成果有关。     

Stressful experiences in relation to depth of sedation in mechanically ventilated patients

In mechanically ventilated patients, sedatives and analgesics are commonly used to ensure comfort, but there is no documented knowledge about the impact of depth of sedation on patients' perception of discomfort. The aim of this study was, therefore, to investigate the relationship between stressful experiences and intensive care sedation, including the depth of sedation. During 18 months, 313 intubated mechanically ventilated adults admitted to two general intensive care units (ICU) for more than 24 h were included. Patients (n = 250) were interviewed on the general ward 5 days after ICU discharge using the ICU Stressful Experiences Questionnaire. Patient data including sedation scores as measured by the Motor Activity Assessment Scale (MAAS) were collected from hospital records after the interview. Of the 206 patients with memories of the intensive care, 82% remembered at least one experience as quite a bit or extremely bothersome. Multivariate analyses showed that higher proportion of MAAS score 3 (indicating more periods of wakefulness), longer ICU stay and being admitted emergent were factors associated with remembering stressful experiences of the ICU as more bothersome. The findings indicate that the depth of sedation has an impact on patients' perception of stressful experiences and that light sedation compared with heavy seems to increase the risk of perceiving experiences in the ICU as more bothersome. In reducing discomfort, depth of sedation and patient comfort should be assessed regularly, non-pharmacological interventions taken into account and the use of sedatives and analgesics adapted to the individual requirements of the patient.     

Toward less sedation in the intensive care unit: a prospective observational study

Purpose

Excessive sedation is associated with prolonged mechanical ventilation and longer intensive care unit (ICU) and hospital stays. We evaluated the feasibility of using minimal sedation in the ICU.

Methods

Prospective observational study in a university hospital 34-bed medico-surgical department of intensive care. All adult patients who stayed in the ICU for more than 12 hours over a 2-month period were included. Intensive care unit admission diagnoses, severity scores, use of sedatives and/or opiates, duration of mechanical ventilation, length of ICU stay, and 28-day mortality were recorded for each patient.

Results

Of the 335 patients (median age, 61 years) admitted during the study period, 142 (42%) received some sedation, most commonly with midazolam and propofol. Sedative agents were administered predominantly for short periods of time (only 10% of patients received sedation for >24 hours). One hundred fifty-five patients (46%) received mechanical ventilation, generating 15?240 hours of mechanical ventilation, of these, only 2993 (20%) hours were accompanied by a continuous sedative infusion. Self-extubation occurred in 6 patients, but only 1 needed reintubation.

Conclusions

In a mixed medical-surgical ICU, minimal use of continuous sedation seems feasible without apparent adverse effects.     

Natural history of dental plaque accumulation in mechanically ventilated adults: A descriptive correlational study

Objective

The purpose of this study was to describe the pattern of dental plaque accumulation in mechanically ventilated adults. Accumulation of dental plaque and bacterial colonisation of the oropharynx is associated with a number of systemic diseases including ventilator associated pneumonia.

Research methodology/design

Data were collected from mechanically ventilated critically ill adults (n = 137), enrolled within 24 hours of intubation. Dental plaque, counts of decayed, missing and filled teeth and systemic antibiotic use was assessed on study days 1, 3, 5 and 7. Dental plaque averages per study day, tooth type and tooth location were analysed.

Setting

Medical respiratory, surgical trauma and neuroscience ICU's of a large tertiary care centre in the southeast United States.

Results

Plaque: all surfaces >60% plaque coverage from day 1 to day 7; molars and premolars contained greatest plaque average >70%. Systemic antibiotic use on day 1 had no significant effect on plaque accumulation on day 3 (p = 0.73).

Conclusions

Patients arrive in critical care units with preexisting oral hygiene issues. Dental plaque tends to accumulate in the posterior teeth (molars and premolars) that may be hard for nurses to visualise and reach; this problem may be exacerbated by endotracheal tubes and other equipment. Knowing accumulation trends of plaque will guide the development of effective oral care protocols.     

机械通气患者实施音乐干预的随机对照研究

目的探讨音乐干预降低机械通气患者焦虑水平以及稳定机械通气患者生理指标的效果。方法将150例机械通气患者随机分为音乐组、耳机组、空白组,采用中国版状态焦虑量表（C-SAI）对三组研究对象干预前后的焦虑水平进行测定,同时记录心率、呼吸率和血压。结果干预后音乐组C-SAI评分（40．54±8．34）分,耳机组（47．52±9．25）分,空白组（52．02±10．20）分,三组患者干预前后比较差异均有统计学意义（P〈0．01）;音乐组患者干预前后心率、呼吸率、收缩压和舒张压的变化均有统计学意义（P〈0．01）。结论音乐干预与戴耳机均有降低机械通气患者焦虑水平的作用,且音乐的作用更明显,音乐可以稳定机械通气患者心率、呼吸率、收缩压和舒张压。     

Hyperglycaemia and mortality in critically ill patients

Objective To describe hyperglycaemia as a possible marker of morbidity and mortality in critically ill medical and surgical patients admitted to a multidisciplinary ICU.Design Prospective cohort study.Setting A 13-bed non-cardiac multidisciplinary ICU in a university hospital.Patients and participants Adult patients consecutively admitted to the ICU in a 6-month period. Patients with fewer than 2 days stay in the ICU and patients with known diabetes were excluded.Measurements and results At admission a registration form was filled in including demographic data, first and second day APACHE II scores, infections and daily maximum blood glucose level. In surgical patients, high maximum blood glucose level during the stay in ICU was correlated with increased mortality, morbidity and frequency of infection. In medical patients, we found a non-significant trend towards a correlation between hyperglycaemia and morbidity and mortality, respectively.Conclusions High blood glucose level during the stay in ICU was a marker of increased morbidity and mortality in critically ill surgical patients. In medical patients the same trend was found, but non-significant. The population of patients in the present study are heterogeneous and the results from surgical critically ill patients should not be generalised to medical patients.