Should Total Intravenous Anesthesia Be Used to Prevent the Occupational Waste Anesthetic Gas Exposure of Pregnant Women in Operating Rooms?

In today’s age, anesthesiologists have a large number of inhalational, intravenous, and regional anesthesia agents in their armamentarium. The type of anesthesia to be administered depends on the patient’s profile, the provider’s preference, and associated comorbidities. Inhalational anesthetic agents are frequently used because of rapid recovery and ease of titration of their alveolar concentration. However, it is associated with the potential health hazards of waste anesthetic gases (WAGs) to the health care workers working in the operating room (OR), more importantly to pregnant women, and most of the studies have focused on them. Professionals (anesthesiologists, surgeons, nurses, and related health care workers) active in the OR and the postanesthesia care unit (PACU) are the people most exposed to WAGs. The environment pollution with WAGs may occur due to 3 causes: anesthetic techniques, anesthesia workstation, and OR without scavenging system.1 Improper anesthetic techniques may include poorly fitting face masks, an insufficiently inflated tracheal tube or laryngeal mask cuff, and circuit leaks.1 The potential health hazards of WAGs include transient problems such as nausea, irritability, and fatigue, and, more important, long-term complications such as teratogenic effects that have an insidious onset.2 Prolonged exposure to WAGs can cause DNA damage in OR personnel.1,3 It can also cause impairment of the antioxidant defense system in exposed professionals.1 Souza et al4 in their study highlighted that the exposure to modern WAGs resulted in genomic instability as studied by cytotoxic and proliferative changes, detected in the exfoliated buccal cells from anesthesiologists who had been exposed to WAGs for at least 2 years. They hence suggested that exposure of the OR personnel to these WAGs should be minimized. The effect of WAG exposure on the reproductive health of male staff working in the OR has not been studied enough. Wyrobek et al5 compared semen samples from 46 anesthesiologists who had worked a minimum of 1 year in a hospital OR with scavenging devices and 26 beginning anesthesiology residents who served as controls. The authors did not find any significant differences in concentrations and percentages of sperm having abnormal head shapes between the 2 groups. They suggested that limited exposure to anesthetic gases does not significantly affect sperm production in an OR with modern gas-scavenging devices. However, men working in an OR without scavenging system should be studied further for possible human spermatotoxic effects. Occupational exposure of female OR personnel is reported to be associated with 50% increased risk of early pregnancy loss,6 low birth weight, and congenital anomalies in children born to mothers exposed to WAGs during pregnancy7,8 (Table).Table.: Studies Evaluating the Health Hazards Associated With Exposure to WAGs on Female OR StaffIn a study conducted at the University of Michigan, Ann Arbor, Gauger et al9 compared obstetric complications between female pediatric anesthesiologists (defined as those having >75% pediatric practice who were likely to have higher exposure to WAG during induction and due to the use of uncuffed tubes) and female anesthesiologists performing primarily adult anesthesia. Their study showed a higher prevalence of pregnancy loss among pediatric anesthesiologists than among nonpediatric anesthesiologists. Scavenging systems in pediatric surgery and maternity units result in 40%–94% decrease in nitrous oxide and sevoflurane exposure. However, the exposures were still higher than recommended.10 Similarly, nurses involved in postanesthesia care have been found to be exposed to concentrations of halogenated gases and nitrous oxide above permissible limits. Hasei et al11 also found that occupational exposure to WAGs occurs during inhaled induction even when the OR is equipped with a WAG scavenging system. They suggested that to decrease occupational exposure to anesthetic gases, induction with intravenous anesthetics is a better method. The US National Institute of Occupational Safety and Health guidelines permit an exposure of 25 ppm for nitrous oxide and 2 ppm for halogenated anesthetic gases.11 Anesthetic gas leakage in the OR can be minimized by careful handling of facemasks, vaporizers, and flowmeters and identification of leaks in high- and low-pressure systems. An effective air renewal using a scavenging system is recommended to prevent theater pollution with anesthetic gases.12 Volatile anesthetic agents are a potential occupational health hazard not only in the OR but also to the recovery staff. In health care providers working in PACUs, the amount of inhaled WAGs can be reduced by personal protective equipment such as ISO-Gard mask (Teleflex Medical, Triangle Park, NC),13 which can be placed on the patient’s face. This actively scavenges WAGs exhaled by patients recovering from anesthesia in the PACU. However, it requires suction for scavenging of WAGs that is provided by the institution’s regulated vacuum source. A survey conducted in India14 found that the availability of scavenging systems was limited to only 33.5% of hospitals. This is due to the high initial investment cost of scavenging system in resource-limited countries. The estimated cost of the installation of a vacuum pump–based scavenging system would be around 50,000 US dollars. In developing countries with a per capita income of <4000 US dollars and the government health care expenditure barely 1.5% of gross domestic product, it is a huge task to install medical gas pipeline system and scavenging system in all ORs all over the country. Moreover, anesthesia work stations with safety features for low-flow gases are also not available at most such places, requiring halogenated anesthetic agents to be used with high fresh gas flow, thereby increasing the exposure of WAG. The cost of inhalational anesthesia is related to fresh gas flow rates, which can be lowered to provide considerable savings. However, a 1-time cost of implementing a scavenging system would be more cost-effective than total intravenous anesthesia (TIVA) in the long term. Intravenous drug administration has evolved to become a popular alternative to inhalational anesthesia. TIVA is defined as a mode of general anesthesia administered exclusively by the intravenous route and in the absence of all inhalational agents.15 TIVA is indicated in patients with risk of malignant hyperthermia, long QT interval (QT) syndrome (corrected QT interval [QTc], ≥500 milliseconds), history of severe postoperative nausea and vomiting (PONV), “tubeless” ear-nose-throat/thoracic surgery, patients with anticipated difficult intubation/extubation, neurosurgery to limit intracranial volume, surgery requiring neurophysiological monitoring, and myasthenia gravis/neuromuscular disorders to avoid neuromuscular blockers. It may also be used in anesthesia in nontheater environments and daycare surgery.15 Compared to volatile anesthetic techniques, TIVA offers several potential advantages. These include reduced incidence of PONV, less emergence delirium, reduced risk of organ toxicity, and reduced atmospheric pollution.15 Disadvantages of TIVA include the need for programmable syringe pumps and increased possibility of patient awareness. Nowadays, target-controlled infusion system is used to manage the concentration of intravenous anesthetic drugs in the plasma. Various authors have found different results regarding cost of TIVA in comparison with inhalational anesthesia. Visser et al16 found that anesthesia costs were >3 times greater for propofol TIVA, without economic gains from shorter stay in the PACU. Ozkose et al17 found fastest recovery, less incidence of PONV, pain, and lowest additional costs in the PACU in TIVA group. However, the total cost was significantly higher in the TIVA group than in the sevoflurane and isoflurane groups (52.73, 29.99, and 24.14 US dollars, respectively) (P < .05). Kumar et al18 in their meta-analysis also found that the total cost of TIVA was significantly higher in comparison to inhalational anesthesia. Cattano et al19 found no statistically significant difference between TIVA with propofol and inhalational anesthesia with sevoflurane regarding postoperative pain, PONV, narcotic administration, and recovery time. Contrary to the results of others, Horng et al20 found that the cost of TIVA with propofol was less than that of inhalational anesthesia. These issues are extremely complex as indirect costs should be considered too, such as possible differences in staff workload resulting from postoperative side effects. Aware of the aforementioned complications of WAG, and because of nonavailability of scavenging system, the female anesthesia providers working in our ORs prefer TIVA over inhalational anesthetic agents during their pregnancy. The presence of a pregnant woman in an OR may be considered as a new indication for TIVA. Depth of anesthesia can be monitored using various modalities like bispectral index and entropy. ORs without scavenging system should make it a part of their standard practice to notify all female staff entering an OR about the potential harms of WAGs and the need to inform the concerned authorities if they are pregnant. The decision to install scavenging system is with the hospital authorities (mostly government), while decision to give TIVA can be made at the clinician’s level. The adverse events in pregnant and nonpregnant women workers due to inhalational anesthetic agents should be evaluated in retrospective cohorts, and guidelines should be framed regarding acceptable dose, duration of exposure, and absolute contraindications of inhalational anesthesia. Anesthesiologists who spend a large portion of their lives in ORs should take this initiative for their community. DISCLOSURES Name: Ankur Sharma, MD, DNB, MNAMS, PDCC. Contribution: This author helped write, draft, and review the manuscript and search the literature. Name: Pradeep Bhatia, MD, FICCM, FICA. Contribution: This author helped in the concept and design of the manuscript and helped review the manuscript. Name: Varuna Vyas, MD. Contribution: This author helped write and draft the manuscript and helped with critical revision of the manuscript. Name: Priyanka Sethi, MD. Contribution: This author helped write the manuscript. Name: Narender Kaloria, DM. Contribution: This author helped write the manuscript. Name: Lovepriya Sharma, MBBS. Contribution: This author helped write the manuscript. This manuscript was handled by: Ken B. Johnson, MD.