Anticholinergics are medications which competitively block the neurotransmitter acetylcholine on the choline receptors. There are natural (atropine, scopolamine) and synthetic derivatives (glycopyrrolate). Their clinical effect occurs at the muscarinic (M₁–M₅) postganglionic acetylcholine receptors in organs, and at the nicotinic postganglionic acetylcholine receptors at autonomic ganglia and at the motor end plate.

Standard doses hardly have any effect on the nicotinic acetylcholine receptors, so that anticholinergics are normally classified as being selective antimuscarinergic [1].

Table 28.1 compares the effects of various anticholinergic medications.

Due to the minimal central nervous and ophthalmologic effect, glycopyrrolate is used for the prevention of the oculocardiac reflex. Atropine is preferred to treat acute reflexive bradycardia due to its fast onset of action.

Especially in pediatric patients, the usual anticholinergics, even when given in the normal doses, often cause “atropine fever” due to the inhibition of perspiration.

>> Dr. Aric thought to himself: “How embarrassing! All my concern about the trisomy while I totally forgot to review the characteristics of this surgery… and my board certification exam was only 2 weeks ago!” He stood up at the computer screen again and completed his record.

“I don’t think you’ve ever worked with us before, have you?” questioned the ophthalmologist. “Next time, I’ll warn you in advance. The rest of my tugs on the eye shouldn’t change the heart rate again.” With that, he sunk deeply into his work. Twenty minutes later the monitor sounded an alarm again. Dr. Aric looked up to see the following on the screen:

An increase in heart rate and blood pressure during anesthesia is often an indication of insufficient depth of anesthesia. Apart from the increasing hemodynamic parameters, signs such as sweating, tears, movements, and initiating breathing/dyssynchrony are important clues. The dose of analgesics and hypnotics given repetitively or continually are determined by pharmacodynamic and pharmacokinetic parameters, the pain caused by the procedure, as well as many individual factors. For this reason, there is not yet any fully reliable technique available to monitor anesthetic depth.

If an isolated parameter unexpectedly changes, a technical cause must always be ruled out first. Here, for example, causes could include compression of the blood pressure cuff by the surgical team, double counts of the R and T waves after a change in position of the ECG electrodes, or artifacts caused by diathermy.

>> “The induction was already more than 30 min ago – Oh man, she’s waking up! I hope the laryngeal mask airway doesn’t slide up!” Dr. Aric gave 20 μg fentanyl and 60 mg propofol IV and increased the continuous propofol infusion from 180 to 250 μg/kg/min. In response, the heart rate increased to 120 beats/min, and the blood pressure didn’t show any improvement.

Several causes must now be checked/ruled out: