Propofol
introduction
Propofol belongs to the group of general anesthetics and is characterized by good controllability. The anesthetic accumulates in the body in extremely small quantities and has a short plasma half-life. This means that after a short period of time only half of the original concentration of active ingredient is still present.
Please also read the article on the topic Anesthetics
Propofol is administered through a vein and has a calming and numbing effect. The narcotic is mainly used in general anesthesia to induce and maintain anesthesia in adults and children from the age of six months. In intensive care medicine it plays an important role as a means of sedation. Other areas of application are gastrointestinal reflections and other endoscopic examination methods.
Compared to inhaled, i.e. inhaled anesthetic gases, the side effects of propofol are significantly less pronounced. Above all, nausea and vomiting are less common. On the other hand, possible undesirable consequences after the administration of propofol are a drop in blood pressure and an inhibition of breathing.
Indications for propofol
Propofol primarily plays an important role in general anesthesia. It serves as a means of Initiation as well as maintenance anesthesia. Its application takes place intravenous. Propofol is never administered alone, but always in combination with an active ingredient that relaxes muscles and relieves pain.
Another area of application is Intensive care. Here Propofol fulfills the purpose of a sedating agent. In contrast to anesthesia, the patient is in a kind of twilight state.
Also at endoscopic examinations, like the gastrointestinal mirror, this effect is used.
effect
Propofol has a calming and numbing Effect. This property, as well, be quick onset of action and its good controllability as a result of a short duration of action make it an ideal anesthetic. It can only be applied through a vein.
After intravenous administration, propofol enters the bloodstream brain. There it binds to inhibiting receptors (so-called GABA receptors) and activates them, creating a inhibitory effect on nerve cells caused. As part of induction of anesthesia, the loss of consciousness occurs within 10-20 seconds and lasts for 8-9 minutes with a single dose. Propofol also works inhibiting various reflexessuch as the cough or gag reflex.
The anesthetic still has one relaxing Effect and has a euphoric effect. A sexually disinhibiting and aphrodisiac reaction is also described. These properties explain a possible potential for abuse.
Duration of action
Propofol has only one relative short duration of action. This is mainly due to the short plasma half-life, which is associated with a rapid decrease in blood concentration. After application, the effect sets in within 10 to 20 seconds and decreases if no further application is made after about eight to nine minutes. Need to maintain anesthesia or a twilight state repeated applications or one continuous infusion (continuous continuous infusion).
dosage
To Induction of anesthesia the usual dose is 20 to 40 mg every ten seconds. This continues until the patient can clinically recognize a state of unconsciousness. The usual dose is up to 55 years of age for adults 1.5 - 2.5 mg propofol / kg body weight. Older people have less need for propofol for induction of anesthesia. The same applies to patients with an increased risk of complications during an operation.
Read the article on this Induction of anesthesia.
The Maintenance the anesthesia is done with a dosage of 4 - 12 mg Propofol / kg body weight per hour.
To the pure SedationTo achieve a twilight state, a dosage of 0.3 to 4 mg propofol / kg body weight / hour out.
The dosage in children is to be regarded as separate and generally has a higher value (3-5 mg / kg body weight).
Read the article on this Anesthesia in children.
Side effects of propofol
Despite the good tolerability and controllability, there are some significant side effects. Propofol has only a narrow therapeutic range, which means that there is not much leeway between the desired effect and the undesired side effect. So from the optimal dosage it is not far into the area of over or under dosage.
Propofol has a side effect that has a depressant effect on breathing and the heartbeat. Furthermore, a drop in blood pressure is caused by a reduced vascular resistance. Elderly patients and those with previous heart diseases are particularly affected.
Unwanted effects rarely observed are vivid dreams, some of which are experienced as unpleasant, pain and swelling at the site of the puncture, twitching of individual muscles, coughing, seizures and strong allergic reactions, etc. on the contained soybean oil, which as a solvent gives the propofol its white, milky color. The occurrence of pulmonary edema with propofol administration is described even more rarely. If the anesthetic is mistakenly injected into the tissue instead of the vein, serious tissue reactions can occur.
Please also read the article on the topic General anesthetic side effects.
The so-called propofol infusion syndrome (PRIS) is a very rare complication and describes a life-threatening complex of symptoms after administration of propofol. It is frequently associated with very high doses and long-term infusions. The exact cause has not yet been clarified. Disturbances of the normal cardiac function and rhythm as well as metabolic acidosis (over-acidification as a result of defective metabolic processes) occur in most cases. Rhabdomyolysis (breakdown of skeletal muscles) and acute kidney failure are also common symptoms of infusion syndrome. In addition to measures to support the circulatory system, the immediate discontinuation of propofol is the most important therapeutic step.
Risks of propofol administration
The risks primarily include the possible side effects (see above: Side effects of propofol), in short:
- limited therapeutic range, risk of over / underdosing
- Drop in blood pressure
- Inhibition of respiratory drive and heartbeat
- the rare propofol infusion syndrome (heart and kidney dysfunction, muscle breakdown)
This also harbors another risk Abuse Potential due to the euphoric and relaxing effect. Psychological dependence can arise. People who work in the medical field are primarily affected by this.
Contraindications
Absolute contraindications to propofol use are one Circulatory insufficiency and a Hypovolemia, a lack of fluids in the body. During use, blood pressure can drop, which under such complicating conditions can have dangerous consequences.
So far there are insufficient data on the use during the pregnancy and breast feeding period in front. However, it is not recommended.
Intensive care children under 16 years of age should also not be sedated with propofol. Here, too, the effects are not sufficiently well known.
Manufacturers advise one Soy allergy depends on the application. According to the latest findings, however, this contraindication should be viewed less critically.
Propofol during anesthesia
Propofol is one of the most common narcotics in the world General anesthesia. In combination with a short-acting Painkiller, e.g. Remifentanil or sufentanil, and, depending on the operation, a means for Muscle relaxatione.g. Rocuronium, it serves the Induction and maintenance of anesthesia during a surgical procedure.
After injecting the initial dose, which depends on body weight and age, one will be given continuous continuous infusion. In this way, a constant effective level in the blood is achieved. So-called syringe pumps are controlled by computers and ensure that the infusion with propofol starts evenly. At the same time, they have the advantage that the Depth of anesthesia can be changed quickly by the responsible anesthetist as required.
Ventilation and intubation are carried out after loss of consciousness and elimination of the reflexes. Cardiovascular parameters are continuously monitored during the procedure. The anesthesia is terminated by slowly reducing the anesthetic medication. The patient wakes up inside less minutes back on.
Propofol for a colonoscopy
A colonoscopy is usually performed light twilight sleep carried out. In principle, this type of examination is also possible without sedation. However, a “sleep injection” makes sense because it not only improves the examination conditions, but also significantly improves the patient's health more pleasant and creates a more relaxed situation. In the case of gastrointestinal reflections, the gag reflex is also prevented.
Please also read the article on the topic Anesthesia for a colonoscopy - dangerous?.
Propofol is injected directly into a vein. As a fast-acting narcotic, it works within seconds. Its dosage is based on the constant Monitoring of circulatory function and breathing. Oxygen saturation, breathing and heart rate as well as blood pressure are monitored during the examination. Even when the consciousness is switched off, the patient breathes independently. The patient wakes up just a few minutes after the end of the examination.
