Value of Capnography During Nurse Administered Propofol Sedation (NAPS)

The Role of Capnography in Endoscopy Patients Undergoing Nurse Administered Propofol Sedation (NAPS): A Randomized Study

Propofol is widely used by anaesthesiologists for deep sedation and general anaesthesia. During recent years nurses trained in the use of low dose Propofol sedation (NAPS) during endoscopy have been introduced. The method has been implemented at the endoscopic unit at Gentofte hospital since 2008(1). Propofol has a respiratory depressive effect which may result in depressed oxygen saturation in the blood (hypoxia). Due to a short acting half life this is prevented in the majority of cases. However, in spite of this, hypoxia is experienced in 4,4% of patients receiving propofol during endoscopy at Gentofte Hospital (unpublished data). It is well known that hypoxia constitutes a late expression of reduced oxygen tension in peripheral tissues. Whether the addition of capnography to standard monitoring during NAPS may be of benefit is widely unknown. The aim of this study is to examine whether the additional use of capnography to standard monitoring during endoscopy may improve patient safety in patients undergoing low dose Propofol sedation by reducing the number, duration and level of hypoxic events. The trial is a randomized clinical prospective case-control study.

Intervention group with the addition of capnography to standard monitoring (non-invasive blood pressure, pulse, pulse oximetry, clinical observation of respiration, electrocardiography (ECG) and respiratory frequency measured by the ECG)

Control group without the addition of capnography to standard monitoring (non-invasive blood pressure, pulse, pulse oximetry, clinical observation of respiration, electrocardiography (ECG) and respiratory frequency measured by the ECG)

In the intervention group the NAPS nurse observed possible hypoxia and changes in capnography curves/values during the procedure and was instructed to decrease propofol and take actions against insufficient ventilation* if etCO2 ≥ 7kPa or ≤ 2 kPa for ≥ 1 minute, if respiratory frequency ≤ 8 or a loss of curve shape was registered. *Suction, increase oxygen supply, tongue holder or nasal airway, bag-mask ventilation,paged anaesthesia Discontinued procedures

If the addition of capnography to standard monitoring can reduce the number of hypoxic events in patients undergoing endscopy with NAPS. A hypoxic event is defined as an observed oxygen saturation of less than 92% . Data is collected by a computer with intervals of 12 sec as the smallest possible.

The sum of events registered during procedures (procedure duration is, depending on the type, 3 to 90 minutes)

Whether more or less actions are taken against respiratory insufficiency with or without capnography in patients undergoing endoscopy with NAPS.

The duration of hypoxia is measured as the sum of registrations(each registration represents 12 seconds) with an oxygen saturation of less than 92 percent. Data is collected by a computer with intervals of 12 sec as the smallest possible.

The sum of time with hypoxia registered during procedures (procedure duration is, depending on the type, 3 to 90 minutes)

Saturation is registered every 12 seconds into a computer. Hypoxia (saturation <92%) was divided into three levels of hypoxia: 1. <92% - 90%,2. <90% - 88%, 3. <88%. And the number of events in each group was summed up.

The sum of events registered at each level during procedures (procedure duration is, depending on the type, 3 to 90 minutes)

Inclusion Criteria: aged 18 or above compliant with the criteria of NAPS. Exclusion Criteria: no signed written consent obtained American Society of Anaesthesiologists (ASA) physical status classification > 3 sleep apnoea allergy against soy, eggs and peanuts body Mass Index (BMI) > 35 kg/m2 mallampati Score ≥ 4 acute gastrointestinal bleeding subileus ventricular retention severe COLD ((30% ≤ FEV1 <50%) failed data collection

Slagelse C, Vilmann P, Hornslet P, Jorgensen HL, Horsted TI. The role of capnography in endoscopy patients undergoing nurse-administered propofol sedation: a randomized study. Scand J Gastroenterol. 2013 Oct;48(10):1222-30. doi: 10.3109/00365521.2013.830327. Epub 2013 Sep 2.