Assessment of Capnography in Monitoring Patients During Nurse Administered Deep Sedation With Propofol

1. INTRODUCTION AND RATIONALE Since sedation is increasingly administered by non-anesthesiologists, patient safety during sedation became of increased interest by the Joint Commission for Accreditation of Healthcare Organisations (JCAHO). The current standard of respiratory monitoring for patients during sedation is continuous pulse oximetry with visual assessment of the patient. Clinical research has demonstrated that hypoxemia, secondary to depressed respiratory activity, is a principal risk during sedation. Microstream capnography is a relatively new technology for carbon dioxide (CO2) monitoring. The technique is based on emission of selective infrared wavelengths exactly matching for CO2 absorption. Due to this efficient and selective emission process only small samples of CO2 are necessary to detect alveolar hypoventilation, and accuracy is maintained with a low flow sample rate. Therefore, capnography can provide more useful information on the frequency, effectiveness and regularity of ventilation, than pulse oximetry during procedures accomplished under deep sedation. According to previous reports capnography provides early detection of alveolar hypoventilation before hypoxemia has occurred in nonintubated patients and thereby can improve patient safety during sedation.

This study will provide new information on the efficacy of capnography for early detection of hypoxemia during nurse-administered propofol sedation in adults. Previous studies, involving a paediatric randomized study and a study in adult gastrointestinal endoscopy, were outcome studies with capnography in patients sedated with midazolam in combination with fentanyl or meperidine.4 5 Therefore, we will assess the efficacy of interventions based on capnographic monitoring of respiratory function in nurse-administered propofol sedation. In previously conducted studies independent observers monitored the capnographic display and prompted the medical team of the changes in respiratory activity. In the following clinical trial we will examine normal practice by assessment of the capnogram by the nurse qualified in sedation management. 2. OBJECTIVES At the Centre for Contraception, Sexuality and Abortion (CASA) Leiden abortion procedures are performed under deep sedation using propofol. These procedures are not attended by an anesthesiologist and patient's monitoring is performed by nurses qualified in patient sedation management, using pulse oximetry and their clinical judgement. Supplementary oxygen is not routinely given.

The purpose of this study is to investigate the use of capnography to improve patient safety during deep sedation. This study examines the effectiveness of capnography in early detection and therapy of alveolar hypoventilation during deep sedation in comparison to standard monitoring with pulse oximetry in abortion procedures. The randomized controlled trial determines whether utilizing capnography in women undergoing deep sedation with propofol (monotherapy) for abortion procedures will provide early detection of suboptimal ventilation and reduce hypoxemia. Unlike previous studies we are determined to investigate daily practice when nurses qualified in sedation management assess capnography instead of an independent observer assessing capnography. Therefore, all nurses qualified in patient sedation management and abortion doctors will be trained in assessment of capnography before the trial starts.

The implications of this study for monitoring deep sedation may be generalized to all healthy patients having minimal invasive procedures, particularly when a trained anesthesiologist is not in attendance. 3. STUDY DESIGN This protocol describes a prospective, open, randomized controlled trial with two study arms. All patients receive standard care of monitoring performed by the medical staff. The study examines whether capnography prevents patients from having respiratory events during deep sedation in abortion procedures.Patients randomized to the standard care group receive standard of care using pulse oximetry. In the capnography arm, respiratory monitoring is performed with pulse oximetry and capnography. If the capnogram indicates sub-optimal ventilation and/or apnea, denoted as a flat line on the capnometer for ≥ 15 seconds, a respiratory rate ≤ 6, or a end-tidal CO2 > 50 mmHg, medical staff will intervene by arousing the patient, performing chinlift or jawthrust, abandon from giving additional propofol, or provision of oxygen. The nurse qualified in sedation management will assess capnography him/ herself. Medical staff and patients are not blinded for the allocation assignment and the study has an open design. 4. STUDY POPULATION 4.1 Population Participants are recruited at the Centre for Contraception, Sexuality and Abortion Leiden, the Netherlands. The study population comprises female patients (≥ 18 years) undergoing abortion procedures during first or second trimester pregnancies.

4.2 Inclusion criteria Patients were considered for enrolment if they fulfil all of the following inclusion criteria: age 18 years or older, abortion procedures performed until 22 weeks of gestational age, American Society of Anaesthesiologists (ASA) classes I to II, and ability (mental competence) to give informed consent.