Postoperative tremors

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Classification according to ICD-10
T88.5 Other complications due to anesthesia
- post-anesthesia hypothermia
ICD-10 online (WHO version 2019)

As postanesthetic shivering ( shivering ) is called an involuntary, not suppressible tremors that 5-60 percent of patients after anesthesia ( general anesthesia ) or regional anesthesia occurs. In addition to subjective discomfort, this can trigger further complications. There are preventive and therapeutic measures.

causes

During an operation, the body loses heat through various mechanisms. This takes place through thermal radiation , convection (drafts, ventilation), conduction ( operating table ) and evaporation (sweat, surgical wound area, breathing air). These losses are favored by the widening of the vessels ( vasodilation ), which is caused by the anesthetics ( anesthetics ). This is also brought about by regional anesthesia procedures such as spinal or epidural anesthesia . In addition, the thermoregulation in the hypothalamus is largely switched off during anesthesia , so that the body cannot take any countermeasures.

If the effect of the narcotics wears off (after waking up), the body registers the temperature drop and tries to compensate for it. This happens through tremors , whereby heat is generated through increased activity of the skeletal muscles , as well as through vasoconstriction ( vasoconstriction ) in the body periphery.

The fact that postoperative tremors sometimes occur in patients with normal temperature suggests that other mechanisms such as spinal cord reflexes, pain , sympathetic nervous system activity , and respiratory alkalosis may play a role in postoperative tremors, but their role is not precise is understood.

Symptoms and consequences

The consequences for the patient are subjective discomfort and increased pain. Due to the increased muscle contractions , the body's oxygen consumption increases up to five times. In patients with diseases of the cardiovascular system such as coronary artery disease or lung disease, this can exceed the body's ability to compensate, which can lead to a lack of oxygen in the tissue and possibly a heart attack . Furthermore, the pressure in the eye ( intraocular ) and skull ( intracranial ) is increased, which can trigger or worsen diseases there. Even seam insufficiency occur frequently.

Treatment and prevention

The treatment is carried out by external warming as well as the intravenous administration of clonidine or the opioid pethidine ( meperidine ). Physostigmine and tramadol are second-line drugs.

Preventive attempts are made to prevent a drop in body temperature. This is done by warming the patient before the anesthesia ("prewarming") and during the procedure with warming pads and hot air blowers as well as by warming up infusions and rinsing solutions. In the case of general anesthesia, only a low flow of fresh gas is carried out, which reduces the heat loss through ventilation . A ventilation filter (Heat Moisture Exchanger, HME) can also reduce the loss of heat and moisture through ventilation. The core body temperature of the patient is monitored by a temperature probe during interventions over half an hour of anesthesia.

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