Patient-centered steps get them breathing sooner

Formal protocols work for ventilator weaning

(Editor’s note: Long-term intubated patients are defined as those needing help to breathe from a mechanical ventilator for more than three days. Here, weaning is defined as the ability to breathe spontaneously for 24 hours with or without an artificial airway in place. The definition of both terms comes from the American Association of Critical Care Nurses’ Third National Study Group on Weaning.)

A growing cadre of clinical researchers is seeking answers to one of critical care nursing’s most elusive questions, namely: How do long-term ventilator patients respond to weaning under various nursing techniques; and, is there a system of ventilator weaning that will lead to better, more predictable outcomes?

For as long as anyone can recall, efforts to free ICU patients from their dependence on bedside mechanical ventilation devices has been to a great degree determined by nurses. But for the nursing staff, the weaning process for critically-ill patients has been a difficult, day-to-day struggle to get patients to breathe on their own. Mostly, it’s been a struggle for hope against setbacks and patience against frustration.

And in planning and protocol development, nurses who have often worked the closest with patients have virtually been left out of the loop, according to many veteran ICU nurses.

Now, some nurses are calling for a different approach. It reverses many long-held beliefs about when long-term intubated patients should start breathing on their own and offers new ways to begin the weaning process. One such technique, for example, advocates improving the patient’s nutritional requirements before undertaking any formal weaning.

"These are extremely sick patients who suffer from more than the primary underlying disorder. They don’t usually wean in a linear fashion. They have good days and bad days," says Suzanne M. Burns, RN, MSN, an associate professor in the school of nursing at the University of Virginia Health Sciences Center in Charlottesville.

Few answers to proper extubation

Granted, the field of inquiry has turned up few definitive answers as to why some patients wean sooner than others, and how to best develop weaning protocols that successfully work across large patient groups, Burns admits. She and her colleagues are advocating a more systematic, patient-centered approach built on two primary concerns:

• Using a tolerance-based system that allows the patient to dictate when weaning should start and what the rate of progress should be.

• Adopting a holistic view of ventilator weaning that includes, among other things, nutritional support, objective values for pain assessment and sensitivity from nurses, and the patient’s general health status and readiness for weaning.

The common, long-held practice has been to attempt to get patients free of the ventilator almost on ICU arrival. "The effort may work well with patients identified early during admission as short-term ventilator patients, but the long-term patient is usually the one out of 10 or 20 who clearly falls outside these parameters," observes Donna Caracciolo, RN, a cardiovascular nurse in the ICU at St. Vincent Medical Center in Toledo, OH.

Strategies based on initial assumptions that all patients should be started on weaning from day one should be re-examined, Burns maintains. Instead, a more individualistic approach based on each patient’s specific medical condition serves as a better guide for weaning.

Standard physiological predictors for weaning generally have included: A fraction of inspired oxygen of less than 0.5 with arterial partial pressure of oxygen of more than 50 to 60 mm Hg, and vital capacity of 10 mL/kg or more. They’ve also involved maximum inspiratory pressure of less than -20cm H2O; minute ventilation of 10 L/min or less; tidal volume of 5 mL/kg or more; and maximum voluntary ventilation of more than twice the value of minute ventilation.1

Other researchers have debated the value of this standard predictor. Yet, physicians have long known that factors such as respiratory muscle weakness and changes in breathing patterns, respiratory rates, and vital signs are important factors in weaning efforts and outcomes. They also know that other important indicators such as breathing force (negative inspiratory pressure) can change over time and aren’t necessarily reliable measures.

Use a formal, systematic approach

To help nurses begin the weaning process, Burns and her colleagues developed a 26-item assessment tool that combines 12 general factors, such as pulse rate and cardiac output, and 14 respiratory factors — including respiratory rate and arterial blood gas levels — in a single score.

They’ve also designed a clinical pathway for weaning mechanically ventilated patients. The pathway identifies patient-related issues such as mobility, nutrition, gas exchange, and infection potential and outlines outcomes in phases that mark improvement in food-feeding tolerance and recovery rates from underlying disorders. It also guides the patient through treatment from initial assessment for weaning to discharge preparation.

The BWAP (Burns Weaning Assessment Program) is a bedside checklist that attempts to set a minimum standard or threshold for alerting nurses when weaning should begin. The tool can be used in an outcomes management program to focus properly needed clinical interventions and track patient progress. It also can be applied as a threshold for initiating weaning protocols and to start active weaning trials, Burns says. (For a chart showing the BWAP, see p. 5.)

Using a systematic, outcomes-managed approach to weaning will produce better results than the current practice of weaning based on the need for immediate short-term results. "The emphasis is moving away from looking at weaning in terms of simple extubation," says Burns.

"The preferred method focuses instead on break-ing down the monitoring periods into small units of time, and correct problems with the patient’s breathing as they occur and not wait until later," notes Milo Engoren, MD, an anesthesiologist and intensivist at St. Vincent in Toledo.

Engoren has been studying the effects of respiratory failure on a patient’s breathing rate and tidal volume (the amount of air inhaled and exhaled in one breath). The key to speeding up the weaning process could lie in measuring changes in the patient’s breathing pattern, not necessarily the respiratory rate. "The patterns in the tidal volume may tell us more about the ability to wean or not to wean than the rate itself," Engoren says.2

Engoren also endorses a systematic, patient-holistic approach to weaning. "Patients are coming into the ICU who are older and sicker than before. They often have underlying conditions related to past renal failure and strokes. Yet, they’re undergoing cardiac surgery and are being intubated in the ICU."

Therefore, nurses need to consider existing problems with the patient before beginning the weaning protocol. "The key is to try and optimize the patient’s condition and address the issues that may be interfering with the weaning," Engoren says.

References

1. Burns SM, Clochesy JM, Goodnough Hanneman SK, et al. Weaning from long-term mechanical ventilation. Am J Crit Care 1995; 4:4-20.

2. Engoren M. Approximate entropy of respiratory rate and tidal volume during weaning and mechanical ventilation. Crit Care Med 1998; 26:1,817-1,823.

Sources

To obtain a free copy of the Burns Weaning Assessment Program, contact the University of Virginia Patient Foundation. Telephone: (804) 924-2175. Fax: (804) 924-1583.

For further information on long-term ventilator weaning research, contact:

Suzanne M. Burns, RN, MSN, RRT, associate professor of nursing, School of Nursing, University of Virginia Health Sciences Center, McLeod Hall, Charlottesville, VA 22903. E-mail: smb4h@virginia.edu.

Milo Engoren, MD, anesthesiologist and intensivist, St. Vincent Medical Center, Department of Anesthesiology, 2213 Cherry St., Toledo, OH 43608-2691. E-mail: engoren@pol.net.

Jan Weber, public relations, American Association of Critical Care Nurses, 101 Columbia Ave., Aliso Viejo, CA 92656-1491. Telephone: (800) 809-2273. E-mail: www.aacn.org. Ask for information concerning the Third National Study Group on Weaning.