Moderate to deep procedural sedation: a safety challenge for anaesthesiologists

Moderate to deep procedural sedation: a safety challenge for anaesthesiologists

  • Issue 66

Chief editor note: With this interesting paper we are initiating a new rubric, CONTROVERSIES, dealing with topics that are not part of the general consensus in our profession. We invite our members and readers to send us their opinions about the place of a non-anaesthesiologist in the field of sedation outside the operating room.

T. A. Knape

Risks of Sedation

Moderate and deep procedural sedation, like general anaesthesia, are very useful techniques for gastroenterology, interventional radiology, interventional cardiology and electrophysiology labs, and other areas of care, but are associated with risk. While consciousness is retained, the patient only responds after being spoken to vigorously or given a painful stimulus. The lowering of consciousness is associated with important consequences in vital function; the most important primary risk being suppression of ventilation to such an extent that hypoxemia occurs or the upper airway obstructs due to relaxation of muscles secondary to the medications used, leading to hypoventilation or apnoea, especially when it is not observed or noticed. The patient’s condition may deteriorate very rapidly, especially when the patient is not in good health or with significant comorbidity. So the primary risks are the consequence of inadequate ventilation and secondary are changes in circulation, again secondary to sedation medications causing hypotension or rhythm disturbances.

The most important risk factor to consider when delivering sedation is the patient themselves, their health status or their comorbidities. Therefore it is very important that the health status of the patient is screened prior to the procedure and if possible to optimize the medical condition of the patient. It makes an enormous difference whether the patient undergoing sedation only is 24 years old and in good health or is a patient 72 years old and suffering from hypertension, diabetes type 2, and asthma. These screening procedures can be done quite easily by having the patient complete a relevant health questionnaire.

Of course the length of the procedure may be a factor. While many procedures may last only 30 minutes, in interventional cardiology we now see procedures that last for many hours, for example in ablation cases with severe rhythm disturbances. Of course, as the level of sedation used deepens, risk increases. A patient receiving light sedation where consciousness is retained definitely has less risk than patients with moderate to deep sedation.

Because the drugs used for moderate to deep sedation are usually a combination of a very potent short-acting opioid, pain killer, and a hypnotic, the potential effect on ventilation and the airway is most important and the practitioner has to be trained to cope with any complications. The most important consequence is the resultant hypoxemia or ventilatory arrest where the patient stops breathing, as they may have a deleterious effect in cerebral or cardiac hypoxemia. These are of course very dangerous and unwanted adverse effects of the procedure. It’s very important to monitor these patients not only by direct observation, but also by interpreting the data that comes from cardiovascular and ventilatory monitoring. The integration of the patient observation and the monitor data guides the sedation practitioner in providing a safe procedure for the patient.

Adverse Event Prevention

If you ask any anaesthesiologist whether he or she has been involved in a complication of moderate to deep sedation, especially when delivered by a non-anaesthesiologist, virtually every anaesthetist who worked in the 1980s would say they have had to resuscitate or restore ventilation on an emergency basis. That was a driver to create a guideline focused on high quality and safe moderate to deep sedation. That has been the key driver for us for getting involved in this field of moderate to deep sedation, where of course the Helsinki Declaration of Patient Safety in Anaesthesiology of 2011 also has been a very important driver to proceed in developing guidelines to make moderate to deep sedation safer for patients.

In addition to the major events with potential patient injury or death, it is very easy to imagine that when you have a busy endoscopy suite confronted with patients who are either under-sedated and not cooperative or over-sedated and having respiratory depression events, the procedure will take more time to perform, and working conditions for the endoscopists are suboptimal.

When we introduce our program using specially-trained sedation nurses, the endoscopists are enthusiastic, not only because of a potentially safer procedure but also that the working conditions for the endoscopies improved considerably. They could perform their investigations more easily and faster, allowing more procedures per day with greater ease. Based on data from our hospital, we did 340 moderate to deep sedation procedures in 2007 and 4,000 in 2015. This demonstrates a need for not only safe sedation but also an increase in efficiency and economics.

It is our goal to try and make the monitoring conditions, the conditions of the monitoring of the patients, equal in all those areas, especially when one specialty starts with the moderate to deep sedation procedures; it will usually take some time before everything is in quite full working order.

These procedures can be performed not only across the hospital, but also outside the hospital in freestanding clinics, granted the principles discussed earlier such as screening patients, education of sedation practitioners, and presence of the adequate monitoring equipment are met. At least one person who is qualified to perform advanced cardiac life support should be immediately available where the procedure takes place and all personnel should be competent in basic life support skills. It is also important that the clinic has an arrangement with a nearby hospital, so if an adverse event does occur, quick access to a hospital with intensive care facilities and appropriate care is available.

Tracking of sedation-related events or complications differs substantially from country to country. In the Netherlands, each medical facility should have a sedation committee and maintain a database of all sedations performed including all complications and adverse events. This database should be a basis for regular discussions about the status of safety in the hospital or facility involved. The health inspectorate also controls these procedures very carefully and emphasizes the need for a quality improvement program to review any complications or events. There is no national program or registry that centrally gathers data. It may be different in other countries, but to my knowledge, there is in fact very little tracking of sedation complications or events.

Sedation Monitoring

It is very important that a trained clinician whose only task is to administer the sedative drugs also observe the consequences and that adequate monitoring be used, especially ventilation monitoring. One of our requirements is use of pulse oximetry and capnography to monitor ventilation. Why capnography? Well, when a patient is hypoventilating and in fact suffering from insufficient ventilation, a pulse oximeter will reveal normal oxygenation for a very long period of time, even when the patient has been hypoventilating for a long time. The degree of hypoventilation can best be monitored by use of the capnography waveform. Previously it was difficult to sample in non-intubated patients, but there are now devices on the market that provide a semi-quantitative display of the expiratory capnogram in non-intubated patients. Therefore, we believe that capnography and oximetry monitoring are pivotal for safe administration of moderate to deep sedation in addition to direct observation.

It is not only important to have the etCO2 number, but also the waveform, because the waveform can give you an indication of the adequacy of ventilation, whether there is regular breathing, interrupted breathing, or an obstruction. So not only the etCO2 but the waveform is very important to determine whether ventilation is adequate or not. Capnography disposables for non-intubated patients developed by industry provide a reasonable CO2 waveform and a realistic indication of ventilation. The sampling of exhaled gases using these modern disposable devices for general practice is more than enough.

The use of CO2 insufflation during endoscopy is becoming more commonplace and is a challenge to capnography, especially in its impact on the etCO2 number. Therefore, it is very important that the waveform is observed and not only the absolute number of the end tidal CO2. The waveform allows the sedation practitioner to clearly interpret whether the patient is ventilating adequately. Even in patients who receive CO2 insufflation by the gastroenterologist, the combination of clinical observation of the patient and observation of the capnography waveform combined with pulse oximetry allows the sedation practitioner to make an adequate judgment of the status of the ventilation. So although it’s an impediment, it is not a contraindication for us.

Pulse Oximetry Use

Measuring oxygenation is important. Oximetry is a very useful tool, but when a patient has stopped breathing or is hypoventilating due to sedatives or opioids, it may take minutes and minutes before you see desaturation. Although the patient is not breathing adequately, you have the impression that nothing is wrong because the oxygen saturation is still normal. By the time the oxygen saturation starts to drop you are very late in compensation and intervention. What capnography offers is a much earlier sign that something is going wrong in spontaneous ventilation, be it by hypoventilation or upper airway obstruction. At a very early phase when that happens it gives the sedation practitioner enough time to make the correct diagnosis and to correct the situation when hypoventilation or upper airway obstruction occurs. When you do not have capnography, it would take minutes and minutes before you are signalled by the pulse oximetry signal that something is wrong and that may be too late. In fact, by the time the pulse oximetry signal goes down, you have to be very afraid of the damage that hypoxemia causes to the heart or the brain. And this can be prevented quite easily by capnography, which may serve as a very early warning sign that something is going wrong with the ventilation of the patient.

You must also consider that in most cases supplementary oxygen is administered to the patient using the same disposable as for capnography sampling. This further elevates the arterial oxygen tension, which can cause a further delay in recognition if only pulse oximetry is being used, and a dangerous rise in arterial CO2 and drop in pH could occur. By the time the oxygen saturation drops, you are already in a dangerous situation and it becomes a question of whether you can rescue the patient by mask ventilation or intubation. Using capnography allows you to identify hypoventilation or airway obstruction early, even when supplemental oxygen is in use.

Data Supporting Capnography

There is sometimes conflicting but mostly positive data that advocates the use of capnography in the sense that it really improves safety. Once you start using capnography, it is very difficult to create a double-blind study because of the fact that the sedation practitioners who use capnography quite rapidly say we cannot safely provide sedation without capnography anymore. So while the number of studies is limited, the clinical experience of sedation practitioners who provide sedation using pulse oximetry and capnography say we don’t want capnography to be withdrawn from our practice, because the integrated monitoring science using capnography has been very beneficial in identifying patients who we have to intubate and where ventilation is at risk.

Preference for Propofol Sedation

If you look at clinical practice, the stability of sedation using propofol is far better than with Midazolam, and when you ask patients they speak for themselves. A lot of patients who have been sedated using Midazolam and an opioid in the past definitely prefer sedation by propofol. Propofol makes sedation far easier to control by a trained sedation practitioner than Midazolam in combination with an opioid. The practice here is usually giving boluses of low doses of opioids with a continuous infusion of propofol, and, if necessary, small adjustments in the propofol dose. The experience of patients who have received this regimen is that when they are in the recovery room they are fully awake and may leave recovery far earlier than when Midazolam has been used. Midazolam has a longer duration of action on the consciousness of patients than propofol. The advantages of propofol in combination with short-acting opioids are definitely much preferred to the use of Midazolam in my opinion for most cases

Program for Sedation by Non-Anesthesia Sedation Practitioners

In the Netherlands, there was a great need for practitioners who could provide moderate to deep sedation due to the growing number of sedation cases and a shortage of qualified physician anaesthetists. The Minister of Health stimulates the principle of reshuffling responsibilities between doctors and non-physician practitioners. The Minister of Health really stimulates that and would like to examine whether a number of procedures currently performed by physicians can also be safely performed by well-trained practitioners such as we see where nurses are providing care for chronic patients suffering from hypertension or diabetes. Also, within the hospital we see the transfer of medical obligations or medical procedures to non-physician personnel, for instance from doctors to physician assistants or well-trained nurses. But specifically the request for moderate to deep sedation and the shortage of qualified physician anaesthetists has compelled us to develop a program where non-physician personnel could provide sedation with the same quality and safety level as we were accustomed to when doctors would do that.

In the Netherlands, anaesthesia is considered to be a team effort consisting of an anaesthesiologist and an anaesthesia nurse, which means that for many cases the anaesthetist is supervising anaesthesia in two operating rooms where anaesthesia nurses are charged with the continuous monitoring of the patients. In Belgium, for example, these anaesthesia nurses do not exist. There are no anaesthesia nurses. In Belgium every operating room is manned by a single anaesthetist and that is the case in a number of other countries as well. Then we have to take into account the number of anaesthetists. In our country there is a shortage of anaesthetists, but in some other countries, there are a lot more anaesthetists per capita. For instance, in Italy the number of anaesthetists when compared to the general population is three times higher than in the Netherlands. So there are more medical personnel available. And in some countries such as Israel, the remuneration of sedation procedures for anaesthetists is considerable. So anaesthesiologists have claimed sedation to be their domain. And these issues differ from country to country, so there is no general rule. There is no general rule of harmonization of this practice throughout Europe. That is why the European Union of Medical Specialists has installed a working party to develop safety guidelines for moderate to deep sedation for doctors, but also for non-physician medical personnel. The need for new models is impacted by the different history and structures of healthcare from country to country.

In some countries, the specialty of anaesthesia is very reluctant to let the domain of moderate to deep sedation go to other healthcare personnel. It is a political question. They are afraid if they lose the domain of moderate to deep sedation then non-medical or non-physician sedation practitioners will be introduced. So it depends again on the structure of the country and on the healthcare organization of the country whether the idea of a non-physician sedation program will be accepted in other countries as well. Every country has to deal with enormous demand for monitored deep sedation and a shortage of personnel that can provide it.

In the Netherlands, there is a single national training program for moderate to deep sedation practitioners that is offered by six training institutions. Candidates have to complete the program and pass an exam and they are then allowed to enter a national registry, which is maintained by the Netherlands Association of Anesthesia Nurses and they are able to work in any area of care where sedation is provided. To maintain their certification, they must document completion of at least 100 moderate to deep sedations annually and provide proof of sufficient continuous professional development and education.

When selecting training candidates, we consider competence in airway management and ventilation. And although we are not allowed to exclude candidates beforehand, our experience is that nearly all of the students are former anaesthesia nurses. We have a few others such as a paediatric intensivist or intensive care nurse who are now involved in sedation of patients and so once more the vast majority are anaesthesia nurses. It is an advantage when a person already has skills and competences in airway management, ventilation, and circulation because these are the most important skills required to be a safe sedation practitioner.

The training program is a part-time training program for one year based on training in physiology, pharmacology, airway management, risk assessment, cardiovascular care, and the various procedures of moderate to deep sedation. Pharmacology includes the various drugs that may be used for sedation including propofol but other sedation agents as well.

One of our sedation practitioners has developed a technique for moderate to deep sedation where the MRI signal is used to synchronize the high-frequency ultrasound treatment in patients, for example with renal tumours. It is important that the patient’s ventilation is very regular. For these cases we have developed a technique using a combination of ketamine and propofol, which provides a regular breathing pattern required for the treatment. So information about the pharmacology of these drugs is very important. Within the training year, the candidates have to provide moderate to deep sedation in 50 cases with personal observation by an anaesthesiologist and in another 50 cases with an anaesthesiologist directly available within one minute. And there is of course an assessment program to assess the progress of the knowledge and practical skills of the candidate.

The Dutch guidelines that have been developed for this certification were finalized in 2012 and set up by a committee consisting of representatives from 21 medical societies representing gastroenterologists, dentists, abortion doctors, surgeons, radiologists, cardiologists, and so on. So it has been a multi-disciplinary guideline that also has been accepted by all these national medical societies. These various societies knew about and are aware of the content of the guidelines. That has caused the enormous growth of moderate to deep sedation procedures, not only in our hospital but also in other academic and non-academic hospitals. The health inspectorate also checks regularly whether the guidelines are followed by the hospitals, making inspection visits and determining whether the moderate to deep sedation procedure adheres to the national guideline we have developed.


What we have seen in our hospital and also in other hospitals where the nurse practitioners are practicing is that the incidence of severe adverse events has decreased dramatically. The critical incidents associated with moderate to deep sedation procedures, which we saw regularly in the past years, aren’t happening as often. There is definitely a decrease in the number of events and in their severity in the Netherlands.

I really hope that the European Guideline, which is about to be finished and published, will clarify best practices for moderate to deep sedation in terms of screening of patients, training personnel, adequate monitoring, and adequate aftercare of these patients, and that it will spread across Europe and provide improved quality and safety to patients. It is also important to note that the patients are changing, considerably. Some 30 years ago, patients accepted more or less everything the doctor said was okay, but patients are becoming more demanding and no longer accept procedures with a lot of inconvenience, pain, or discomfort. So the demand for safe procedures is increasing from the patient side and not only from the doctor’s perspective.