SAT and SBT–Def-Tech

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Definition and Techniques for Spontaneous Awakening (SAT) and Spontaneous Breathing Trial (SBT)Protocol

Introduction - Reducing the number of days a patient is on mechanical ventilation has been shown to reduce the risk of VAP. (Brook et al., 1999; Ely et al., 2001; Ely et al., 2003; J. Kress, Pohlman, O'Connor, & Hall, 2000) Strategies for weaning patients off of mechanical ventilation ofteninclude a spontaneous awakening (SAT) and spontaneous breathing trials (SBT). A wake up and breathe protocol using both the SAT and SBT together, rather than separately can significantly reduce the number of days patients are on mechanical ventilation. Girard et. al.(Girard et al., 2008) showed that paired, the SAT and SBT reduced the number of days patients were on mechanical ventilation (3.1 mean difference, 95% CI 0.7-5.6; p=0.02), with a concomitant reduction in the length of hospital stay (4 day difference) when compared to SBT alone. This same technique, often called a readiness-to-wean or sedation protocol, has been used in other institutions with much success. (Blackwood et al., 2011; J. Kress, Pohlman, O'Connor, & Hall, 2000; Quenot et al., 2007) We are using the model Girard et. al. developed in 2008 for this project.

SAT safety Screen and Spontaneous Awakening Trial (SAT)

The SAT consists of two parts, a safety screen and the SAT. (Please see Figure 1 below) Often times this is done by the bedside nurse or respiratory therapist in the early morning. The safety screen attempts to assure the trials will not be used when contraindicated. Patients pass the screen unless:

  1. They are receiving a sedative infusion for active seizures or alcohol withdrawal
  2. They are receiving escalating doses of sedative for agitation
  3. They are receiving neuromuscular blockers
  4. They have evidence of active myocardial ischemia in prior 24 hours
  5. They have evidence of increased intracranial pressure

If the patient passes the safety screen, they proceed to have a SAT. For the SAT, all sedatives and analgesics used for sedation are stopped. Analgesics used for pain are continued. The goal is that the patient can open their eyes to verbal stimuli or can go without sedation for 4 hoursor more without the following:

  1. sustained anxiety
  2. agitation
  3. pain
  4. a respiratory rate of 35 breaths/minute for >= 5 minutes
  5. an SpO2 of less than 88% for >=5 minutes
  6. an acute cardiac dysrhythmia
  7. two or more signs of respiratory distress
  8. tachycardia
  9. bradycardia
  10. use of accessory muscles
  11. abdominal paradox
  12. diaphoresis
  13. marked dyspnea

If a patient fails the SAT, sedatives are started at one half the prior dosage and titrated up as needed.

Safety Screen and Spontaneous Breathing Trial (SBT)

If a patient passes the SAT, the patient is assessed for the SBT safety screen. Patients pass if:

  1. they have adequate oxygenation (SpO2 >=88% on an F1O2 of <=50% and a PEEP <=8 cm H2O)
  2. any spontaneous inspiratory effort in a 5-min period
  3. no agitation
  4. no significant use of vasopressors or inotropes
  5. no evidence of increased intracranial pressure

If a patient fails, he is reassessed for SAT the following day. If the patient passes, they undergo the SBT. For the SBT, ventilatory support is removed and thepatient is allowed to breathe for 120 minutes through either a T-tube circuit of a ventilatory circuit with CPAP of 5cm H2O or pressure support ventilation of less than 7cm H2O. Patients pass the SBT if they don’t develop any of the following failure criteria:

  1. respiratory rate of more than 35 or less that 8 breaths per min for 5 min or longer
  2. hypoxemia (SpO2 < 88% for >=5 min)
  3. abrupt change in mental status
  4. an acute cardiac arrhythmia
  5. two or more signs of respiratory distress
  6. tachycardia
  7. bradycardia
  8. use of accessory muscles
  9. abdominal paradox
  10. diaphoresis
  11. marked dyspnea

If a patient fails the SBT, he is reassessed for SAT the following day. If a patient passes, the patient’s physicians are notified for possible extubation.

Measuring Compliance with SAT and SBT for this Project

The above protocol is adapted from “Efficacy and safety of a paired sedation and ventilator weaning protocol on the duration of mechanical ventilation,” by Girard et. al. (2008). While this approach was found to be very effective as a research protocol, it may be challenging to measure compliance with this approach in our ICUs.

A more practical approach to measuring the SAT and SBT is described below. Lets start with measuring SAT using 3 steps (Figure 2).

Step 1. We start with the question, “Is the patient responsive to verbal stimuli?” If the answer is yes, they have already “passed” the SAT. If the answer is no, then the healthcare provider needs to assess the appropriateness of an SAT.

Step 2. “Has the patient received any medication for sedation?” Sedative medications for this purpose include: Lorazepam, Midasolam, Propofol, Fentanyl, Morphine, Demorol, Dilaudid, Haldol and Precedex. If the patient is not receiving medication for sedation, the reason this patient is not responsive is not related to sedation medication and an SAT is not warranted. An “NI” would be entered when this is the case. If the patient is receiving sedation medication, then the healthcare provider needs to continue to assess the appropriateness of an SAT.

Step 3. “Have medications for sedation been held during the past 24 hours?” If the answer is yes, then the SAT has been performed, whether or not there has been any “formal” trial. If the answer is no, then the patient may be eligible for an SAT; the SAT Safety Screen would need to be performed first.

If the patient cannot pass the safety screen, then he is reevaluated in 24 hours. If he passes the screen, he goes on to the SAT itself. The SAT safety screen and SAT are described both in the text above and in the flow diagram itself. If the patient passes the SAT, he can go on to the SBT safety screen. If the patient does not pass the SAT, sedation should be cut to ½ original dosage and titrated up for pain control and agitation.

While implementing SAT and SBT are best done together, we will be measuring the two concepts independently. Both the SBT safety screen and the SBT itself are described in the text above and in the flow diagram below.

The SBT safety screen should only be performed after the patient passes the SAT. The patient passes the screen if they meet the criteria listed. If the patient does not pass the screen, he is still marked “Y” as having an SBT. If the patient passes, he goes on to the SBT. An “N” would only be noted if the patient did not have an SBT safety screen or an SBT

If the patient has an SBT, whether or not he passes, he is marked as “Y” in that column and can be considered for extubation. If he does not pass, his ventilation status is returned to his baseline (before the trial) and he should start at the question: “Is the patient responsive to verbal stimuli?” 24 hours later.

Figure 1.Spontaneous Awakening (SAT) and Spontaneous Breathing Trial (SBT) Protocol.


Figure 2.Measuring Compliance with SAT for this project.

References

Blackwood, B., Alderdice, F., Burns, K., Cardwell, C., Lavery, G., & O'Hallaran, P. (2011). Use of weaning protocols for reducing duration of mechancal ventilatoin in critically ill adult patients: Cochran systematic review and meta-analysis. BMJ, Jan 13

Brook, A. D., Ahrens, T. S., Schaiff, R., Prentice, D., Sherman, G., Shannon, W., et al. (1999). Effect of a nursing-implemented sedation protocol on the duration of mechanical ventilation. Critical Care Medicine, 27(12), 2609-2615.

Ely, E. W., Meade, M. O., Haponik, E. F., Kollef, M. H., Cook, D. J., Guyatt, G. H., et al. (2001). Mechanical ventilator weaning protocols driven by nonphysician health-care professionals: Evidence-based clinical practice guidelines. Chest, 120(6 Suppl), 454S-63S.

Ely, E. W., Truman, B., Shintani, A., Thomason, J. W., Wheeler, A. P., Gordon, S., et al. (2003). Monitoring sedation status over time in ICU patients: Reliability and validity of the richmond agitation-sedation scale (RASS). JAMA : The Journal of the American Medical Association, 289(22), 2983-2991.

Girard, T. D., Kress, J. P., Fuchs, B. D., Thomason, J. W., Schweickert, W. D., Pun, B. T., et al. (2008). Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (awakening and breathing controlled trial): A randomised controlled trial. Lancet, 371(9607), 126-134.

Kress, J., Pohlman, A., O'Connor, M., & Hall, J. (2000). Daily interruption of sedative infusion in critically ill undergoing mechanical ventilation. N.Engl.J.Med., 342, 1471-1477.

Quenot, J., Ladoire, S., Devoucoux, F., Doise, J., Cailliod, R., Cunin, N., et al. (2007). Effect of a nurse-implemented sedation protocl on the incidence of ventilator associate penumonia. Crit Care Med, 35(9), 2031-9.

CSTS –Appendix K: Definition and Technique for SAT and SBT Protocol

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© Armstrong Institute for Patient Safety and Quality, Johns Hopkins Medicine