Bowel motility
The term intestinal motility refers to the movement of the intestine. The sympathetic nervous system has an inhibiting influence, so intestinal motility is reduced. In contrast, the parasympathetic nervous system promotes motility.
In epidural anesthesia, the sympathetic nerve fibers are the primary targets of anesthesia. This eliminates the inhibitory effect on the intestine – motility increases. In principle, this is always accompanied by increased digestion.
Thus, epidural anaesthesia can stimulate digestion in patients with chronic constipation, for example. However, epidural anaesthesia alone is not a treatment option for chronic constipation or intestinal paralysis (lat. : ileus).
Instead, the increased intestinal motility should be considered a desirable side effect. To facilitate the puncture, the patient is asked to bend his back as far as possible in a sitting position; this is often referred to as a “cat’s hump”. Alternatively, epidural anaesthesia can also be applied in a lateral position.
The subsequent use of the spray disinfectant on the back is often perceived as cold, but not unpleasant. In order to find the right puncture site, the doctor palpates anatomical structures on the back, especially the vertebrae of the spine. In order to make the insertion of the puncture needle as painless as possible, the corresponding area of skin is anaesthetized using a local anaesthetic.
The doctor then advances the puncture needle to the so-called epidural space. Here the medication, the so-called local anesthetic (narcotic), which makes the area painless, is injected. In addition, a strong analgesic (opioid) is injected in the same step.
After the needle has been removed, the epidural anaesthesia would now in principle ensure freedom from pain for short surgical procedures. One speaks of the so-called “single shot”. As a rule, however, it is recommended to insert the end of a thin plastic tube (catheter) into the epidural space.
Through this catheter, local anesthetics and opioids can be continuously delivered by means of a pump. The advantage over the single shot is that the continuous administration ensures permanent freedom from pain even in the days after the operation. The entire procedure of epidural anesthesia (PDA) usually takes no longer than ten minutes.
It is usually not perceived as particularly painful. The effect of pain elimination begins after a few minutes. After further progression of the drug’s effect, there is a loss of sensation of touch and pressure and then finally a loss of muscle tone – in the case of an epidural for surgery on the knee, this would mean that the legs are no longer actively mobile.
While in general anesthesia the patient is ventilated by a machine and is not conscious, these two functions are not impaired in epidural anesthesia. However, the combination of PDA and general anesthesia is common practice (so-called “combined anesthesia”) and is usually favored not least by the patient himself, since he does not want to consciously witness the events during the operation.The advantage of combined anesthesia is also that the circulatory burdening anesthetic agent can be dispensed with (see general anesthesia side effects). This is particularly important for patients with severe pre-existing conditions in the lung or heart area (e.g. coronary heart disease, cardiac insufficiency, heart attack, cardiac arrhythmia, COPD, asthma).
In the days following the operation, the PDA system is checked daily by employees of the anaesthesia department. The entry point of the catheter covered with a patch is monitored for signs of infection and if necessary the pump is refilled with medication. This connection explains when the sensation returns to the corresponding body region: the aim is to achieve a state immediately after the operation in which the patient perceives pressure sensations when touching the body region, but not pain.
Technically and pharmacologically, this state can usually be reached within an hour – but it should not be concealed that in practice it is often difficult to achieve this narrow degree between sensation of touch and freedom from pain. The great benefit of all regional anaesthesia procedures (epidural anaesthesia, spinal anaesthesia), apart from the optimal pain therapy, are the advantages resulting from early mobilisation: Shorter hospital stay, lower risk of blood clots (thrombosis, pulmonary embolism) and bed pressure ulcers (decubitus) and higher patient comfort. The pumps allow the patient to apply painkillers via the catheter in addition to the continuous administration of medication (so-called basal rate) according to his or her own needs (so-called bolus administration).
The amount of the bolus and the time that must lie between two boluses are set by the physician on the device beforehand – this prevents accidental overdosing by the patient. This form of pain therapy can be used even if it is not related to surgery. In this case, the catheter is also placed over the procedure described above, and can be left in place for up to several months. Fields of application are, for example, the inhibition of pain in labour or the treatment of pain in angina pectoris.
