Comparison of five clinical weaning indices

Weaning from mechanical ventilation: where were we then, and where are we now?

Weaning patients from long-term mechanical ventilation (LTMV) has been an important focus of clinical process improvement initiatives and research for decades. The purpose of this article is to describe the science that drives our current weaning practices, including (1) preweaning assessment, (2) individualized weaning plans, (3) weaning prediction, (4) the use of protocols and guidelines for weaning trials and sedation management, (5) timing of tracheostomy placement, and (6) system initiatives for the management of LTMV patients. Finally, this article discusses potential interventions for improving the outcomes of patients who require prolonged mechanical ventilation.

Clinical Prediction of Weaning and Extubation in Australian and New Zealand Intensive Care Units

Our objective was to describe, in Australian and New Zealand adult intensive care units, the relative frequency in which various clinical criteria were used to predict weaning and extubation, and the weaning methods employed.

Participant intensivists at 55 intensive care units completed a self-administered questionnaire, using visual analogue scales (0=not at all predictive, 10=perfectly predictive, not used=null score) to record the perceived utility of 30 potential predictors.

Survey response rate was 71% (164/230). Those variables thought most predictive of weaning readiness were respiratory rate (median score 8.0, interquartile range 7.0 to 8.6) effective cough (7.3, 5.9 to 8.2) and pressure support setting (7.2, 6.0 to 8.0). The most highly rated predictors of extubation success were effective cough (8.0, 7.0 to 9.0), respiratory rate (8.0, 7.0 to 8.5) and Glasgow Coma Score (7.9, 6.1 to 8.3). Variables perceived least predictive of weaning and extubation success were P0.1, Acute Physiological and Chronic Health Evaluation score II, mean arterial pressure, electrolytes and maximum inspiratory pressure (individual median scores <5). Most popular clinical criteria were those perceived to have high predictive accuracy, both for weaning (respiratory rate 96%, pressure support setting 94% and Glasgow coma score 91%) and extubation readiness (respiratory rate 98%, effective cough 94% and Glasgow Coma Score 92%). Weaning mostly employed pressure support ventilation (55%), with less use of synchronised intermittent mandatory ventilation (32%) and spontaneous breathing trials (13%).

Classic ventilatory performance predictors including respiratory rate and effective cough were reported to be of greater clinical utility than other more recently proposed measures.

Weaning from ventilation--current state of the science and art

Weaning from mechanical ventilation has attracted a growing interest recently in the medical and nursing press. Attempts have been made to determine a patient's readiness to wean, define criteria for successful weaning and enhance the weaning process through the developments of protocols. Key to this work is the role of the critical care nurse. Transferring the role and the responsibility of weaning from the traditional perspective of the intensivist to the nurse is not without challenges. Inherent is the need for skill and expertise and the willingness to accept this level of responsibility, not questioned in the medical role, but worthy of consideration when transferred to nurses. Key to successful weaning and weaning is redefined for the purposes of this paper, is continuity of care, knowing the patient and the development of patient-centred, individualized weaning plans. Critical care nurses have an important role to play. This is particularly so when the patient experience is to be understood. There is relatively little research conducted in this area, yet this is an important consideration if we are to fully understand and embrace the role of patients in their weaning. Weaning in the context of critical care can be challenging. To wean the difficult-to-wean or the long-term-weaning patient requires great skill and expertise. Expertise in this context has not been fully explored, yet research suggests that these patients are not allocated expert nurses to care for them because they are not seen as critically ill. It may be that this group of patients would benefit from a transfer to a weaning centre as suggested by the Modernisation Agency in 2002. This would greatly challenge the way we, as critical care nurses, perceive weaning in critical care.

A 2-minute pre-extubation protocol for ventilated intensive care unit patients

BACKGROUND

Clinicians often are challenged with safely predicting the optimal time of extubation for ventilated patients. Commonly used weaning parameters have poor positive predictive value for successful extubation.

METHODS

A total of 213 intubated patients in our 20-bed surgical intensive care unit were enrolled in a trial to test a prospective, observational, 2-minute extubation protocol (TMEP). Daily measurements were obtained on all intubated patients who met criteria, which included adequate oxygenation, systolic blood pressure, heart rate, hemoglobin, Glasgow Coma Score greater than 10t, absence of significant metabolic/respiratory acidosis, and absence of therapeutic or neurologic paralysis. During TMEP, endotracheally intubated patients were physically disconnected from the ventilator for a 2-minute period of observation while spontaneously breathing room air. Patients were extubated if they tolerated the trial without clinically significant desaturation or alteration of vital signs or mental status.

RESULTS

The TMEP reliably predicted successful extubations in 203 of 213 patients (95.3%). Patients who required reintubation had a longer intensive care unit stay and a longer hospital stay.

CONCLUSIONS

TMEP is a simple and reliable method of predicting successful extubation.

Issues in weaning from mechanical ventilation: literature review

AIM

The aim of this paper is to raise questions on the effect of skill mix and organizational structure on weaning from mechanical ventilation.

BACKGROUND

Mechanical ventilation is an essential life-saving technology. There are, however, numerous associated complications that influence the morbidity and mortality of patients receiving intensive care. Therefore, it was essential to use the safest and most effective form of ventilation for the shortest possible duration. Because of the potential complications and costs of mechanical ventilation, research to date have focused on accurate weaning readiness assessment, methods and organizational aspects that influence the weaning process.

METHOD

In early 2005, the literature was reviewed from 1986 to 2004 by accessing the following databases: Medline, Proquest, Science Direct, CINAHL, and Blackwell Science. The keywords mechanical ventilation, weaning, protocols, critical care, nursing role, decision-making and weaning readiness were used separately and combinations.

DISCUSSION

Controversy exists in weaning practices about appropriate and efficacious weaning readiness assessment indicators, the best method of weaning and the use of weaning protocols. Arguably, the implementation of weaning protocols may have little effect in an environment that favours collaboration between nursing and medical staff, autonomous nursing decision-making in relation to weaning practices, and high numbers of nurses qualified at postgraduate level.

CONCLUSION

Further research is required that better quantifies critical care nurses' role in weaning practices and the contextual issues that influence both the nursing role and the process of weaning from mechanical ventilation.

Assessing Nutritional Status in Chronically Critically Ill Adult Patients

• Background Numerous methods are used to measure and assess nutritional status of chronically critically ill patients.

• Objectives To discuss the multiple methods used to assess nutritional status in chronically critically ill patients, describe the nutritional status of chronically critically ill patients, and assess the relationship between nutritional indicators and outcomes of mechanical ventilation.

• Methods A descriptive, longitudinal design was used to collect weekly data on 360 adult patients who required more than 72 hours of mechanical ventilation and had a hospital stay of 7 days or more. Data on body mass index and biochemical markers of nutritional status were collected. Patients’ nutritional intake compared with physicians’ orders, dieticians’ recommendations, and indirect calorimetry and physicians’ orders compared with dieticians’ recommendations were used to assess nutritional status. Relationships between nutritional indicators and variables of mechanical ventilation were determined.

• ResultsInconsistencies among nurses’ implementation, physicians’ orders, and dieticians’ recommendations resulted in wide variations in patients’ calculated nutritional adequacy. Patients received a mean of 83% of the energy intake ordered by their physicians (SD 33%, range 0%–200%). Patients who required partial or total ventilator support upon discharge had a lower body mass index at admission than did patients with spontaneous respirations (Mann-Whitney U = 8441, P = .001).

• Conclusions In this sample, the variability in weaning progression and outcomes most likely reflects illness severity and complexity rather than nutritional status or nutritional therapies. Further studies are needed to determine the best methods to define nutritional adequacy and to evaluate nutritional status.

Weaning Readiness and Fluid Balance in Older Critically Ill Surgical Patients

• BackgroundFew studies address predictors for successful weaning of older adults from mechanical ventilation.

• ObjectiveTo develop a clinical profile of older patients who are successfully weaned from long-term mechanical ventilation.

• MethodsForty patients in the trauma and surgical intensive care unit who were at least 60 years old were enrolled in the study after 3 days of active weaning and were monitored daily until successfully weaned or until the end of the 14-day study. Hemodynamic and gas exchange variables, fluid balance, oxygen cost of breathing, and scores on the Burns Weaning Assessment Program were analyzed.

• ResultsCompared with patients who were not weaned, successfully weaned patients required mechanical ventilation for 5.3 days, started active weaning earlier (mean 10.7 vs 14.5 days, P = .04), had lower mean negative daily fluid balances in the beginning (−0.394 vs 1.107 L, P = .004), and had lower mean net cumulative fluid balances (6.856 vs 16.212 L) at the time of enrollment. They also maintained both a lower mean net cumulative fluid balance (10.753 vs 25.049 L, P= .02) and a negative daily fluid balance (−0.389 vs 1.904 L, P = .03) throughout. Their mean central venous pressure decreased over time and was significantly lower (P&lt;.001).

• ConclusionPersistent positive fluid balance in older surgical patients is associated with prolonged mechanical ventilation. Estimates of fluid balance might be useful in weaning older patients from long-term mechanical ventilation.

The experience of four outcomes managers: an institutional approach to weaning patients from long-term mechanical ventilation

Care of patients requiring long-term mechanical ventilation (LTMV) is the focus of many hospitals nationwide. Because the care of patients who require LTMV is complex and morbidity and mortality are high, associated costs often exceed reimbursement. This article describes a successful institutional program for the care of the patient population requiring LTMV using advanced practice nurses (APNs) in the role of outcomes managers (OMs). So that others may benefit from the experiences of the clinicians, this article describes the historical background, the selection and qualifications of APNs, the process APNs use to manage and monitor the patients, role challenges, and associated outcomes.

The science of weaning: when and how?

Weaning patients from long-term mechanical ventilation continues to be a goal of clinicians and scientists and the hospitals charged with their care. This article describes the science of the "wean" and the "how" of weaning. A goal of scientists has been to develop predictors that determine accurately the optimal time to initiate weaning. Unfortunately to date none has emerged as superior. Quite simply, predictors do not predict. In contrast, methods that decrease variation in care practices have demonstrated positive outcomes. The methods include protocols for weaning trials and sedation and other system initiatives inclusive of a multidisciplinary plan of care or clinical pathway.

Implementation of an institutional program to improve clinical and financial outcomes of mechanically ventilated patients: One-year outcomes and lessons learned*

OBJECTIVE

To determine the effect of an institutional approach to the care of patients requiring mechanical ventilation for longer than three consecutive days in five adult intensive care units (ICU) on clinical and financial outcomes.

DESIGN

A multidisciplinary team was selected from five adult ICUs to design the approach. Planning occurred from August 1999 to September 2000. The process was called outcomes management (OM) and included an evidence-based clinical pathway, protocols for weaning and sedation use, and the selection of four advanced practice nurses (called outcomes managers) to manage and monitor the program.

SETTING

The project was completed in a 550-bed mid-Atlantic academic medical center. The ICUs included the following: coronary care, medical ICU, neuroscience ICU, surgical trauma ICU, and thoracic cardiovascular ICU.

PATIENTS

The sample included 595 pre-OM patients and 510 post-OM patients mechanically ventilated for greater than three consecutive days.

INTERVENTIONS

Full implementation of the OM approach occurred in March 2001. Retrospective baseline (18 months pre-OM) and prospective (12 months OM) clinical and financial data were compared.

MEASUREMENTS AND MAIN RESULTS

Statistically significant differences in clinical outcomes were demonstrated in the managed patients compared with those managed before the institutional approach. Outcomes include ventilator duration (median days declined from ten to nine; p =.0001), ICU length of stay (median days declined from 15 to 12; p =.0008), hospital length of stay (median days declined from 22 to 20; p =.0001), and mortality rate (declined from 38% to 31%, p =.02). More than 3,000,000 US dollars cost savings were realized in the OM group.

CONCLUSIONS

This institutional approach to the care of patients ventilated >3 days improved all clinical and financial outcomes of interest. To date, few similar initiatives have demonstrated similar results. The approach and lessons learned in this process improvement project may be helpful to other institutions attempting to improve outcomes in this vulnerable population.

Weaning from ventilation in paediatric intensive care: an intervention study

OBJECTIVE

To standardise the paediatric intensive care unit (PICU) team's approach to weaning paediatric patients from mechanical ventilation.

METHOD

The study employed a time series design over 2 years. A total of 220 patients (pre-intervention n=107 and post-intervention n=113) were studied. Independent variables measured in both the pre- and post-intervention groups included total ventilation time (TVT), weaning duration (WD), and length of stay (LOS), as well as quality indicators (weaning failure and reintubation rates).

RESULTS

The pre-intervention analysis demonstrated an existing fluctuation between outcome variables. When outcome indicators were compared between the pre- and post-intervention groups, both TVT and LOS were longer post-intervention (median difference: TVT -15.8 hours, P<0.068; and LOS -23.75 hours, P<0.088). WD was comparable between groups (median difference: WD -1.5 hours, P<0.427). Quality indicators were better post-intervention. Kaplan-Meier survival analysis demonstrated that long-term ventilated patients post-intervention had a reduced probability of remaining ventilated.

CONCLUSION

Weaning children from mechanical ventilation can be performed safely and effectively with the aid of collaborative guidelines. Although times were prolonged, the quality indicators were slightly improved, indicating that quicker was not always better. Long-term ventilated patients, in particular, would appear to benefit from weaning guidelines.

Clinical validation of dysfunctional ventilatory weaning response: The Spanish experience

PURPOSE

To validate dysfunctional ventilatory weaning response (DVWR).

METHODS

Descriptive, longitudinal, and prospective study of 80 patients from three different university hospitals in Spain.

FINDINGS

Twenty defining characteristics were associated with DVWR; eight factors from the NANDA model and four non-NANDA factors were associated with the diagnosis. Adventitious breath sounds, decreased air entry on auscultation, anxiety, and adverse environment resulted as predictive variables of dysfunctional response.

CONCLUSIONS

The incidence of DVWR is high, although clinical nurses do not always recognize it. DVWR has different manifestations and associated factors along the course of the weaning stage, but anxiety is associated with DVWR across the time continuum.

PRACTICE IMPLICATIONS

Validation of DVWR for use in nursing clinical practice is supported. Early detection of predictive variables could help to identify DVWR and facilitate the diagnosis in the clinical practice.

Subjective Perceptions and Physiological Variables During Weaning From Mechanical Ventilation

• Background As costs related to mechanical ventilation increase, clear indicators of patients’ readiness to be weaned are needed. Research has not yet yielded a consensus on physiological variables that are consistent correlates of weaning outcomes. Subjective perceptions rarely have been examined for their contribution to successful weaning.

• Objective To explore the subjective perceptions of dyspnea, fatigue, and self-efficacy and selected physiological variables in patients being weaned from mechanical ventilation.

• Methods Data were collected prospectively on 68 patients being weaned from mechanical ventilation. Subjective perceptions were measured by using 3 visual analog scales; physiological variables were measured by using the Burns Weaning Assessment Program and a patient profile. Weaning outcomes were recorded 24 hours after data collection.

• Results Participants were primarily white women and required mechanical ventilation for a mean of less than 4 days. Participants reported mild dyspnea, moderate fatigue, and high weaning self-efficacy. High Pao2, low Paco2, stable hemodynamic status, adequate cough and swallow reflexes, no metabolic changes, and no abdominal problems were associated with complete weaning (P = .05). Subjective perceptions were associated with physiological variables but not with weaning outcomes.

• Conclusions Multidimensional assessment of both primary and secondary indicators of readiness to be weaned is necessary for timely, efficient weaning from mechanical ventilation. Primary assessments include physiological variables related to gas exchange, hemodynamic status, diaphragmatic expansion, and airway clearance. Secondary assessments include perceptions related to key physiological variables. Additional research is needed to determine the predictive value of physiological variables and perceptions of dyspnea, fatigue, and self-efficacy.

Weaning Older Patients From Long-term Mechanical Ventilation: A Pilot Study

• Background As older persons in the intensive care unit increasingly require long-term mechanical ventilation, accurate indications of readiness for weaning from ventilatory support are needed to avoid premature extubation.

• Objective To describe temporal changes in pulmonary and systemic variables in older adults receiving long-term mechanical ventilation.

• Methods After 3 days of unsuccessful attempts at weaning from ventilatory support, 10 trauma and surgical patients more than 60 years old were monitored daily. Previously reported predictors of the duration of mechanical ventilation and weaning outcome were measured, including hemodynamic and gas exchange variables, oxygen cost of breathing, and the score on the Burns Weaning Assessment Program.

• Results The 6 patients who could be weaned from ventilatory support were younger (median age, 71.5 years) than the 4 patients who could not be weaned (median age, 80 years). Patients who could be weaned were ready for weaning by day 11 of their stay in the intensive care unit and required an additional 5.5 days of mechanical ventilation; those who could not be weaned were not ready for weaning until day 17. All patients initially had increases in oxygen consumption during weaning; those who were successfully weaned had decreases before extubation. Respiratory rate, maximal inspiratory pressure, the ratio of Pao2 to fraction of inspired oxygen, and mean arterial pressure were higher in patients who could be weaned, and oxygen cost of breathing and central venous pressure were lower.

• Conclusion Further study of weaning in older adults is warranted.

Effect of a collaborative weaning plan on patient outcome in the critical care setting

OBJECTIVE

The process of weaning from mechanical ventilation can be complex, requiring collaborative care planning by members of the healthcare team. Improved outcomes have been demonstrated to result from collaborative decision-making processes (e.g., when ventilator teams were utilized). The purpose of this study was to evaluate the effect of a collaborative weaning plan (CWP) on length of time on mechanical ventilation, length of stay in the intensive care unit (ICU), and cost.

DESIGN

A new, collaborative weaning plan in the form of a weaning board and flowsheet was introduced into a medical intensive care unit (MICU) setting. A pre- and post-quasi-experimental design using historical controls was used to test the hypotheses. Attempts to control for the effects of history were made by collecting data related to patient, staffing, and organizational variables that could independently effect outcome.

SETTING

MICU in a west coast teaching hospital.

PATIENTS

Critically ill patients receiving mechanical ventilation for 3 days or greater.

INTERVENTION

Implementation of a collaborative weaning plan.

MEASUREMENTS

Outcomes studied included length of stay in the MICU, length of time patients were mechanically ventilated in the MICU, cost per MICU stay, and the incidence of complications (e.g., reventilation, readmission to the ICU, and mortality rate).

MAIN RESULTS

The CWP decreased length of stay in the MICU by 3.6 days (p =.03) and length of ventilator time by 2.7 days (p =.06). There were no significant differences between groups related to cost or incidence of complications.

CONCLUSIONS

These results support the usefulness of collaborative structures (such as weaning boards/flowsheets) in decreasing ICU length of stay.

[Weaning from mechanical ventilation. The aim of nursing research]

Management of patients difficult to wean from the ventilator is a practical challenge in which professional nurses are deeply involved.The clinical research applied over the last years has tried to describe the characteristics of weaning phenomenon and the associated factors, to find predictive outcomes to guide clinical decisions, to search new strategies to conduct the protocols and to identify the most effective modes of weaning. In this paper a critical review of the current knowledge from a nursing perspective is done. The weaning conceptual model proposed by the American Association of Critical Care Nurses (AACN) group has been used as a theoretical framework.

Long-term ventilator management strategies: experiences of two hospitals

Historically, negative clinical and economic outcomes have been associated with patients who need long-term mechanical ventilation. Institutions and clinicians charged with the care of these patients are understandably interested in exploring clinical strategies that assure positive outcomes. This article describes the evidence base for clinical pathways, weaning teams, protocols, and care-managed approaches. In addition, the article describes how different elements of system initiatives designed for a university teaching hospital and a community hospital were implemented and evaluated. The systematic approaches encourage multidisciplinary input and decrease variation, thus improving both quality and cost.

Evaluation of compliance with a computerized protocol: weaning from mechanical ventilator support using pressure support

STUDY OBJECTIVES

To use a computerized consultation system to evaluate the feasibility of a mechanical ventilator weaning protocol which used the rapid shallow breathing index to guide adjustments in pressure support. A program to monitor user compliance and reasons for noncompliance was built into the computerized consultation system.

METHODS

A total of nine critically ill patients (ten weaning episodes) were enrolled in the protocol. The respiratory therapists performed routine computer charting in the electronic database. They accepted or declined the explicit instructions generated by the computerized protocol and displayed on the bedside terminal. The consultation program monitored whether accepted instructions were implemented by the user.

RESULTS

Patient's therapy was controlled by protocol for a total of 1075 h (mean 108 h, range 4 to 339 h) and 94.8% (1321/1394) of instructions were followed by the clinical staff. Of the 42 instructions clinical staff refused to follow, 23 (55%) were extubation instructions. There were 52 (3.7%) incorrect instructions generated with 24 software errors, 21 errors in underlying logic, and seven user misunderstanding errors.

CONCLUSIONS

A high level of user compliance with this protocol was achieved. The methods described herein to monitor compliance and reasons for noncompliance within a protocol are reusable in the domain of mechanical ventilation and possibly in other domains.

Multiple stab wounds: a short-term respiratory case study

Respiratory management is a role that is of paramount importance to intensive care nurses. Proactive nursing allows a nurse to have a positive effect on a patient's condition by actively improving the patient's status and setting priorities of care, avoiding deterioration wherever possible. In this account of the respiratory management of a patient who has sustained bilateral pneumothoraces following multiple stab wounds to the chest and back, the physiological assessment of the patient is described and a proactive respiratory plan of care is formed. Anatomy, physiology and pathophysiology in relation to pneumothoraces, metabolic acidosis and magnesium links with functional residual capacity are addressed. The potential risk of Adult Respiratory Distress Syndrome (ARDS) following direct and indirect lung injury is discussed. Recent research into ventilation modes and into areas of nursing practice relating to respiratory management are also considered.

Psychophysiologic predictors of weaning from mechanical ventilation in chronic bronchitis and emphysema

This study identified psychophysiologic variables related to successful weaning in 27 ventilator-dependent patients with chronic bronchitis and emphysema (CBE) from two long-term care pulmonary-specialty hospitals in South Central Florida. Subjects were studied from admission until weaning occurred (successful weaning without mechanical ventilation) or until they were transferred without being weaned or died (unsuccessful weaning). The study subjects, 15 males and 12 females, ranged in age from 56 to 89. Baseline data on the variables (age, mastery, hope, social support, dyspnea, and rapid shallow breathing index [RSBI]) were not statistically significant by gender. The logistic regression model identified mastery and RSBI to be the best predictors of successful weaning (model chi 2 = 16.33, df = 2, and p value = .0003; prediction rate 82%).

Qualitative analysis of patients' work during mechanical ventilation and weaning

OBJECTIVE

To describe patients' recollections of their experiences during mechanical ventilation and weaning and to extend an evolving nursing theory of weaning.

DESIGN

A qualitative approach that used grounded theory techniques.

PATIENTS AND METHODS

We surveyed 20 hospitalized patients who had recently undergone mechanical ventilation and weaning from the ventilator in a critical care unit. Included in the analysis were any thoughts, feelings, or actions recalled by the patients that were related to the weaning experience.

RESULTS

During ventilation and weaning, patients were engaged to various degrees in what they called "work," which consisted of their efforts to assist in their adjustment and recovery. This work had four themes: sense making, enduring, preserving self, and controlling responses. These themes represented activities by which patients dealt with their personal concerns and cooperated with the therapeutic plan.

CONCLUSIONS

Despite good care during the process, mechanical ventilation and weaning are stressful experiences that require active participation by patients. Patients' work needs to be understood and supported by clinicians to facilitate recovery from mechanical ventilation and weaning.