Signs of Adverse Reaction to Inhalational Anesthetic

Inhalational anesthetics, such as halothane, isoflurane, desflurane, and sevoflurane, are widely used to induce and maintain anesthesia during surgery. Though uncommon, inhalational anesthetics can cause an adverse reaction in different organ systems in both acute and chronic settings. Understanding the risks associated with inhalational anesthetics and recognizing signs of an adverse reaction are critical to improving patient outcomes and minimizing potential long-term health consequences for both patients and healthcare providers exposed to these agents (1).

One of the most significant adverse effects associated with inhalational anesthetics is hepatotoxicity, especially with halothane. Halothane hepatotoxicity can present as mild, self-limited liver injury or, in severe cases, fulminant liver failure, particularly in patients with previous exposure to halothane or certain genetic predispositions (2). Although newer agents such as isoflurane and sevoflurane have a lower incidence of hepatotoxicity, cases of liver injury have still been reported, suggesting that idiosyncratic responses may play a role (2). In addition, genetic polymorphisms in the cytochrome P450 enzymes that metabolize inhalational anesthetics may influence individual susceptibility to liver injury, highlighting the importance of patient history and genetic factors in anesthetic management.

Another area of concern is the neurotoxicity of inhalational anesthetics. Recent research has shown that high levels of exposure to inhalational anesthetics, especially in pediatric and elderly populations, may lead to short-term cognitive impairment or even long-term neurodegeneration in extreme cases. Pediatric studies suggest that overexposure to these agents may disrupt normal brain development, resulting in long-term cognitive and behavioral abnormalities (3). In elderly patients, prolonged exposure has been associated with postoperative cognitive dysfunction (POCD) and delirium. The mechanisms underlying these effects appear to involve increased apoptosis and inflammatory responses in neural tissues, raising concerns about the use of these agents in vulnerable populations (2).

The cardiovascular and respiratory systems are also affected by inhalational anesthetics. These agents are known to cause dose-dependent depression of myocardial contractility and vasodilation, resulting in hypotension (1). Respiratory depression is another common side effect, especially at higher concentrations, because inhalational anesthetics reduce the response to carbon dioxide, leading to hypoventilation. Postoperative hypoxemia may result, particularly in patients with obesity or obstructive sleep apnea. Clinicians must be vigilant and recognize early signs that a patient is having a major adverse reaction to inhalational anesthetics that may put their cardiovascular or respiratory systems at risk.

Because anesthesiologists and surgical teams are regularly in the vicinity of inhalational agents, occupational exposure to inhalational anesthetics is another consideration. Long-term exposure, even at trace levels, has been associated with a higher risk of reproductive problems, malignancies, and neurobehavioral changes in healthcare workers (4). Scavenging systems, proper ventilation, and adherence to safety protocols are essential to protect healthcare workers.

Many factors influence a patient’s reaction to inhalational anesthetics and the risk of an adverse reaction. Anesthesiologists should remain vigilant of key signs that a patient is responding poorly and be prepared to adjust their approach as needed.

References

1. Stachnik J. Inhaled anesthetic agents. Am J Health Syst Pharm. 2006;63(7):623-634. doi:10.2146/ajhp050460

2. Soleimanpour H, Safari S, Rahmani F, Ameli H, Alavian SM. The role of inhalational anesthetic drugs in patients with hepatic dysfunction: a review article. Anesth Pain Med. 2015;5(1):e23409. Published 2015 Jan 7. doi:10.5812/aapm.23409

3. Porter LL, Blaauwendraad SM, Pieters BM. Respiratory and hemodynamic perioperative adverse events in intravenous versus inhalational induction in pediatric anesthesia: A systematic review and meta-analysis. Paediatr Anaesth. 2020;30(8):859-866. doi:10.1111/pan.13904

4. Varughese S, Ahmed R. Environmental and Occupational Considerations of Anesthesia: A Narrative Review and Update. Anesth Analg. 2021;133(4):826-835. doi:10.1213/ANE.0000000000005504