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Among intravenous agents used in general anesthesia, propofol has long been the standard drug of choice due to its rapid onset, short duration, and favorable recovery profile. Its mechanism enhances inhibitory GABAergic transmission, producing reliable sedation and anesthesia. However, propofol is not without drawbacks, as adverse reactions ranging from minor events like injection-site pain to serious complications like propofol infusion syndrome can limit propofol usage.¹ To address these challenges, researchers have pursued alternatives with improved safety and tolerability profiles. In 2017,² ciprofol was first introduced as a next-generation intravenous anesthesia agent that shows potential to replace propofol in clinical practice.

Ciprofol builds on the traditional 2,6-disubstituted phenol structure shared by classic intravenous anesthetics such as propofol but features the addition of a cyclopropyl group that modifies the agent’s chemical and pharmacological properties. This substitution reduces lipophilicity and breaks the symmetry of the parent molecule, which creates a chiral center and produces stereoselective activity at the GABA_A receptor. These structural changes enhance receptor binding affinity and production. This results in a higher receptor affinity for ciprofol over propofol, as confirmed by radioligand-binding assays.³ Additionally, the R-enantiomer of ciprofol demonstrates greater stereoselectivity for the GABA_A receptor than propofol’s S-enantiomer. Together, these results indicate ciprofol has stronger target selectivity and higher action intensity.

Mechanistically, ciprofol functions as both a positive allosteric modulator and direct agonist of the GABA_A receptor. Electrophysiological studies, such as competitive binding assays and whole-cell patch-clamp experiments, confirm that ciprofol facilitates chloride influx by binding to butylbicyclophosphorothionate and t-butylbicycloorthobenzoate targets (two extremely potent GABA receptor antagonists) in the chloride channels of GABA_A receptors through receptor-associated pathways.⁴ The influx of chloride can cause hyperpolarization of nerve cell membranes by increasing the intracellular chloride concentration and further activating GABAergic neurons to achieve central nerve inhibition, producing sedative and anesthetic effects.

In a 2022 preclinical study, both ciprofol and propofol were administered to rats via intravenous injection to assess hypnotic potency and safety. Loss of righting reflex was used as a behavioral marker of anesthesia, with the effective dose (ED₅₀) values calculated based on the proportion of animals losing reflex at different doses. To evaluate safety, the lethal dose (LD₅₀) value was determined by monitoring mortality after escalating doses, and the therapeutic index was then derived from the LD₅₀/ED₅₀ ratio. They found ciprofol has approximately 4–5 times higher hypnotic potencythan propofol and exhibits ahigher therapeutic index, indicative of a wider safety margin.⁵

A prospective, double-blind, single-center RCT enrolled 120 female patients undergoing general anesthesia for gynecological surgery. There were no significant differences between patients who received propofol or ciprofol in terms of induction success rate, duration of successful induction, time to induction (as measured by the loss of eyelash reflex), and tracheal intubation. However, the overall incidence of adverse events was significantly lower in the ciprofol group than in the propofol group (20% vs. 48%, respectively).⁶

Current evidence suggests ciprofol offers certain pharmacological and clinical advantages over propofol. Its structural modifications enhance stereoselectivity and receptor affinity, translating to stronger potency at lower dosage levels. Preclinical studies in murine models demonstrated a higher therapeutic index, supporting a wider safety margin over propofol. Early clinical trials further confirmed the agent’s comparable anesthetic efficacy while reducing the incidence of adverse events. These findings indicate that ciprofol has potential as a next-generation intravenous anesthesia agent to become widely used in the operative setting.

References

1. Mashour G. A., Sanders R. D., and Lee U., Propofol Anesthesia: A Leap Into the Void? Anesthesiology. (2022) 136 (3), 405-407, https://doi.org/10.1097/ALN.000000000000411035120194
2. Zhang C., Li F., Yu Y., et al. Design, Synthesis, and Evaluation of a Series of Novel Benzocyclobutene Derivatives as General Anesthetics. Journal of Medicinal Chemistry. 2017;60(9):3618-3625. https://doi.org/10.1021/acs.jmedchem.7b00253
3. Qin L., Ren L., Wan S., et al. Design, Synthesis, and Evaluation of Novel 2,6-Disubstituted Phenol Derivatives as General Anesthetics. Journal of Medicinal Chemistry. 2017;60(9):3606-3617. https://doi.org/10.1021/acs.jmedchem.7b00254
4. Lu M, Liu J, Wu X, Zhang Z. Ciprofol: A Novel Alternative to Propofol in Clinical Intravenous Anesthesia? BioMed Research International. 2023;2023:1-12. https://doi.org/10.1155/2023/7443226
5. Liao J., Li M., Huang C., et al. Pharmacodynamics and Pharmacokinetics of HSK3486, a Novel 2,6-Disubstituted Phenol Derivative as a General Anesthetic. Frontiers in Pharmacology. 2022;13. https://doi.org/10.3389/fphar.2022.830791
6. Chen B., Yin X., Jiang L., Liu J., Shi Y., Yuan B., The Efficacy and Safety of Ciprofol Use for the Induction of General Anesthesia in Patients Undergoing Gynecological Surgery: A Prospective Randomized Controlled Study. BMC Anesthesiology. 2022;22(1). https://doi.org/10.1186/s12871-022-01782-7

Anesthesia providers may face radiation exposure in their daily work, particularly during procedures that employ imaging technologies such as fluoroscopy. While most attention tends to focus on radiologists and interventional cardiologists, anesthesiologists and nurse anesthetists often stand close to radiation sources, sometimes without full awareness of the risk.

Anesthesia providers experience radiation exposure from both operating rooms and non-operative settings like interventional radiology or catheterization labs. The main source of exposure is scattered radiation from the patient and not the primary beam—increasing physical distance from the patient is critical to reducing exposure. Dosimeter monitoring has revealed that residents’ maximum deep dose equivalent over a three-month period was around 0.50 mSv, and eye exposure was about 0.52 mSv, both well below recommended occupational limits ¹.

In interventional cardiology settings, exposure levels remain low. Analyses of the annual mean effective dose from 2019 to 2023 found values ranging from approximately 0.92 mSv in 2020 down to about 0.65 mSv in 2023. These levels are significantly below the 20 mSv annual occupational limit, though some individual readings did exceed the 1 mSv public exposure threshold ².

Additional research carried out across three Mid-Atlantic hospitals assessed anesthesia providers’ compliance with radiation safety measures in operating rooms. Data from initial observations demonstrated that almost 83% of providers followed appropriate safety precautions such as wearing lead aprons, thyroid shields, or standing more than one meter from radiation sources. Following a brief educational intervention, compliance increased to nearly 96%. This suggests that education and awareness significantly influence safety behaviors ³. In addition, clinical research continues to reinforce the “time, distance, and shielding” principle as foundational for radiation protection, urging heightened awareness among anesthesia providers ⁴.

Anesthesia providers have a certain degree of control over two key factors in their levels of radiation exposure: distance and shielding. While time spent near radiation sources is often dictated by patient care, adhering to proper distance (ideally more than one meter) and utilizing protective equipment (lead aprons, thyroid collars, eye protection) can substantially reduce risk.

Routine use of dosimeters is also advised, though observational data indicate that usage remains low among providers. Working closely with procedural teams, such as by ensuring imaging is paused until protective gear is donned, can further minimize unnecessary exposure.

In general, education initiatives have already demonstrated an impact in boosting compliance, and broader adoption of safety protocols and consistent monitoring will continue to safeguard anesthesia professionals in radiation-prone environments ^5–7.

Radiation exposure among anesthesia providers is generally low, often well within regulatory limits. However, the cumulative effect of repeated exposure, particularly during frequent imaging-guided procedures, warrants continued vigilance. Scattered radiation remains the principal risk, but adherence to basic safety principles (like limiting time near the source, maximizing distance, and employing shielding) can effectively minimize potential harm.

References

1. Wang, R. R., Kumar, A. H., Tanaka, P. & Macario, A. Occupational Radiation Exposure of Anesthesia Providers: A Summary of Key Learning Points and Resident-Led Radiation Safety Projects. Semin Cardiothorac Vasc Anesth 21, 165–171 (2017). DOI: 10.1177/1089253217692110

2. Shbeer, A. Assessment of the Occupational Radiation Exposure of Anesthesia Staff in Interventional Cardiology. Risk Manag Healthc Policy 17, 1093–1100 (2024). DOI: 10.2147/RMHP.S460054

3. Spinella, J. et al. Radiation Safety Practices Among Anesthesia Providers: A Multi-Site Observational Pilot Study. Journal of Radiology Nursing 43, 230–234 (2024). DOI: 10.1016/j.jradnu.2024.08.003

4. Kim, J. H. Three principles for radiation safety: time, distance, and shielding. Korean J Pain 31, 145–146 (2018). DOI: 10.3344/kjp.2018.31.3.145

5.  Kim, T. H., Hong, S. W., Woo, N. S., Kim, H. K. & Kim, J. H. The radiation safety education and the pain physicians’ efforts to reduce radiation exposure. Korean J Pain 30, 104–115 (2017). DOI: 10.3344/kjp.2017.30.2.104

6. Ali, M. A., Salim, B., Siddiqui, K. M. & Khan, M. F. Attitudes and knowledge of anesthesiology trainees to radiation exposure in a Tertiary care hospital. Saudi J Anaesth 14, 459–463 (2020). DOI: 10.4103/sja.SJA_659_19

7. Lalabekyan, B., Rennie, A. & Luoma, V. Principles of radiation safety for anaesthetists. BJA Education 25, 181–190 (2025). DOI: 10.1016/j.bjae.2025.01.005

Regional anesthesia, including spinal and epidural techniques, is widely used in surgical, orthopedic, and obstetric practice due to its benefits in pain control, muscle relaxation, and avoidance of general anesthesia. A critical step in the administration and monitoring of regional anesthesia is the accurate physical assessment of the block level. This ensures that the anesthesia has achieved the desired sensory and motor coverage, confirms the safety and effectiveness of the procedure, and helps detect complications such as an excessively high block or incomplete anesthesia.

Sensory block assessment is the primary physical assessment method used to determine the level of regional anesthesia. Several techniques are commonly used, each targeting specific nerve fibers responsible for sensation. One of the most frequently employed methods is temperature sensation testing. This involves applying a cold stimulus—such as an alcohol swab, ice cube, or ether-soaked gauze—to the skin and asking the patient to report changes in cold perception. The loss of cold sensation indicates blockade of small-diameter sensory fibers and offers a sensitive indication of anesthetic spread.

Another well-established method is the pinprick test, which involves gently pricking the skin with a blunt needle or safety pin. Patients are asked to differentiate between sharp and dull sensations across various dermatomal levels. This test targets the A-delta fibers that transmit pain and provides a reliable estimate of the block’s upper level. However, it is subjective and requires patient cooperation, which can sometimes limit its reliability. Light touch assessment is also used and involves stroking the skin with cotton wool or a gauze pad. It evaluates the larger A-beta fibers, which are usually the last to be blocked and the first to recover. Light touch testing is often used alongside other methods to confirm the full extent of the block.

Motor block assessment complements sensory testing, especially in procedures requiring muscle relaxation or when assessing a patient’s readiness for mobilization postoperatively. The most common tool for motor block evaluation is the Bromage scale. This scale ranges from full movement (grade 0) to complete inability to move the lower limbs (grade 3). Assessment is conducted by asking the patient to flex the knee, lift the leg, or wiggle the toes. Motor block assessment is especially important in labor analgesia and lower extremity surgeries to ensure adequate nerve involvement without unnecessarily compromising patient mobility.

In addition to these physical assessment methods for regional anesthesia, some clinicians assess autonomic blockade, which typically extends several dermatomes above the sensory block level. Though not routinely measured, it can provide important information about the depth of the block. Signs of sympathetic blockade include hypotension, bradycardia, and increased skin temperature in the affected dermatomes. Some studies have explored using infrared thermometers or thermographic imaging to assess changes in skin temperature as an indirect measure of sympathetic block. While promising, these methods are not yet standard practice due to cost, complexity, and variability in interpretation.

Accurate block assessment requires a combination of methods and an understanding of their limitations. Variability in patient response, communication barriers, and preexisting conditions such as neuropathy can affect the reliability of physical assessments. Furthermore, interobserver differences can lead to inconsistent evaluations unless clear protocols are followed. Despite these challenges, combining sensory, motor, and—when necessary—autonomic evaluations provides a more comprehensive and reliable picture of the anesthetic block.

References

1. Greene NM. Distribution of local anesthetic solutions within the subarachnoid space. Anesth Analg. 1985;64(7):715-730. PMID: 3893222.
2. Liu SS, McDonald SB. Current issues in spinal anesthesia. Anesthesiology. 2001;94(5):888-906. doi: 10.1097/00000542-200105000-00030.
3. Klide AM. Anatomy of the spinal cord and how the spinal cord is affected by local anesthetics and other drugs. Vet Clin North Am Small Anim Pract. 1992 Mar;22(2):413-6. doi: 10.1016/s0195-5616(92)50654-4.
4. Kitahata LM. Modes and sites of “analgesic” action of anesthetics on the spinal cord. Int Anesthesiol Clin. 1975 Spring;13(1):149-70. doi: 10.1097/00004311-197513010-00007.
5. Heavner JE. Jamming spinal sensory input: effects of anesthetic and analgesic drugs in the spinal cord dorsal horn. Pain. 1975 Sep;1(3):239-255. doi: 10.1016/0304-3959(75)90041-X.

A genicular nerve block is a minimally invasive procedure used to diagnose or treat chronic knee pain, particularly in cases where other treatments such as medications or physical therapy have not provided adequate relief. This technique targets the genicular nerves—small sensory nerves that transmit pain signals from the knee joint to the brain. By blocking these nerves, the procedure can reduce or eliminate pain, allowing for improved mobility and quality of life ¹.

The genicular nerve block is most commonly used for patients suffering from chronic osteoarthritis of the knee, especially those who are not candidates for knee replacement surgery. It is also used for individuals experiencing persistent post-surgical knee pain or pain following knee trauma. In some cases, the block is used as a diagnostic tool to determine whether a patient is likely to respond well to a longer-term treatment such as genicular nerve ablation ^2,3.

During the procedure, a healthcare provider injects a local anesthetic, often combined with a steroid, near the genicular nerves around the knee. Using fluoroscopy or ultrasound, the provider ensures that the needle is accurately placed; the injected anesthetic temporarily blocks the transmission of pain signals from the knee to the brain.

Genicular nerve blocks are typically performed by pain management specialists, anesthesiologists, or other physicians with specialized training. These providers have expertise in musculoskeletal and nervous system anatomy and the use of image-guided procedures for injections near nerves to ensure precision and safety. The procedure is typically carried out on an outpatient basis and takes less than half an hour. Most patients report only mild discomfort during the injections and can return home shortly afterward. Driving is usually not recommended immediately after the procedure, so arranging for transportation is advised ^1,4–6.

Many individuals experience significant pain relief within hours of the procedure. The duration of relief varies depending on the individual, but it typically lasts several days to a few weeks for diagnostic blocks. If the patient experiences meaningful relief, this can indicate that a more permanent treatment, such as radiofrequency ablation of the genicular nerves, may be effective. In such cases, the nerves are targeted with heat energy to disrupt pain signals more permanently ^4,7,8.

The genicular nerve block is considered safe, but like all medical procedures, it carries some risks. These include temporary soreness at the injection site, bleeding, infection, or allergic reaction to the medications used. Rarely, the procedure may not provide any pain relief, or the relief may be short-lived. Proper patient selection and imaging guidance significantly reduce the risk of complications ^1,9.

The genicular nerve block is an effective, low-risk option for diagnosing and managing chronic knee pain, especially for those seeking alternatives to surgery. When successful, it can lead to longer-term solutions and help restore a patient’s mobility, comfort, and quality of life.

References

1. Genicular Nerve Block. Cleveland Clinic https://my.clevelandclinic.org/health/treatments/24823-genicular-nerve-block.
2. OSC, O. Diagnostic Genicular Nerve Blocks for Knee Pain. Orthopaedic and Spine Center of Newport News https://www.osc-ortho.com/blog/diagnostic-genicular-nerve-blocks-for-knee-pain/ (2021).
3. Genicular Nerve Block | Pain Specialists of America. https://www.psadocs.com/services/genicular-nerve-block/.
4. Hasoon, J., Orhurhu, V. J. & Yazdi, C. Genicular Nerve Blocks for the Management of Chronic Knee Pain Related to Osteoarthritis – A Case Series. Orthop Rev (Pavia) 16, 126046. DOI: 10.52965/001c.126046
5. NYSORA. Genicular Nerve Blocks. NYSORA https://www.nysora.com/techniques/lower-extremity/nysora-com-genicular-nerve-blocks/ (2021).
6. Genicular Nerve Blocks – AOA Orthopedic Specialists. https://www.arlingtonortho.com/conditions/knee/genicular-nerve-blocks/ (2018).
7. Li, W., Xu, F., Chen, F., Cao, L. & Bao, X. Effect of Genicular Nerve Block (GNB) on Pain in Lesions of the Knee Joint: A Meta-Analysis of Randomized Controlled Trials. JPR 18, 511–522 (2025). DOI: 10.2147/JPR.S503937
8. Konya*, Z. Y., Akin Takmaz, S., Basar, H., Baltaci, B. & Babaoglu, G. Results of genicular nerve ablation by radiofrequency in osteoarthritis-related chronic refractory knee pain. Turk J Med Sci 50, 86–95 (2020). DOI: 10.3906/sag-1906-91
9. Ferguson MD, K. & Kalia MD, H., MPH, FIPP, FACPM. Complications of Genicular Nerve Blocks and Ablations. in Complications of Pain-Relieving Procedures 387–391 (John Wiley & Sons, Ltd, 2022). DOI: 10.1002/9781119757306.ch45.

Surgery start time can be influenced by a wide range of factors, from logistical challenges to clinical considerations. These variables can affect surgical efficiency, patient outcomes, and the overall functioning of healthcare systems. Understanding these factors is crucial for optimizing surgical schedules and ensuring timely, safe procedures.

One key factor influencing surgery start time is the patient’s preoperative preparation. Surgeons, anesthesiologists, and nurses must ensure that the patient is ready for surgery, which includes obtaining medical history, conducting laboratory tests, and confirming the patient is fasting, if necessary. Preoperative imaging and screenings are also vital, and delays in completing these tasks can push back start times. Last-minute changes in the patient’s condition, such as fluctuations in blood pressure or an allergic reaction to anesthesia, may also cause delays as the team aims to stabilize the patient ¹.

The coordination of the perioperative team is another significant factor. A typical team includes the surgeon, anesthesiologist, surgical nurses, and other specialists, all of whom must be present and prepared for the surgery. If any member of the team is delayed or unavailable, the surgery may be postponed. Delays can occur due to emergencies in other operating rooms, scheduling conflicts, or another procedure overrunning its scheduled time. Additionally, specialized surgeons or anesthesiologists may not always be available, especially for complex surgeries ^2–4.

The availability of operating rooms plays a critical role in surgery start times. Surgical facilities often have limited ORs, and scheduling conflicts can arise; surgeons may need to adjust start times to accommodate the availability of the OR. Delays may also occur if previous surgeries run over their allotted time or if the operating room requires extra cleaning or setup between procedures. In facilities with high patient volumes or specialized procedures, managing OR availability can be a complex challenge ^5,6.

In addition, anesthesia preparation and equipment setup are also crucial factors affecting surgery start time. The anesthesia team must ensure all medications and equipment are ready and functioning properly, including calibrating anesthesia machines and confirming drug dosages. Similarly, the surgical team must ensure that all required instruments and devices are sterile and ready for use. Delays in equipment availability or malfunctioning devices can significantly impact the start time, as can the need for additional preparation or sterilization of specific instruments ^7,8.

Patient-related factors also play an important role. These can include anxiety, mobility issues, or difficulties with anesthesia induction. For example, patients with anxiety may require additional time to be sedated or reassured before surgery. Those with complex medical histories may need more time for preparation or monitoring, which can cause delays. Ensuring that the patient is adequately prepared and comfortable is essential to a successful surgical outcome ^7,9.

Surgery start time is shaped by multiple factors, from preoperative preparation and team coordination to operating room availability and patient-specific needs. By understanding and managing these variables, healthcare providers can optimize surgical scheduling, leading to timely surgeries, better patient care, and more efficient healthcare delivery.

References

1. Meneveau, M. O. et al. Patient and Personnel Factors Affect Operating Room Start Times. Surgery 167, 390–395 (2020). DOI: 10.1016/j.surg.2019.08.011

2. Firde, M., Ayine, B., Mekete, G., Sisay, A. & Yetneberk, T. Root causes of first-case start time delays for elective surgical procedures: a prospective multicenter observational cohort study in Ethiopia. Patient Saf Surg 18, 23 (2024). DOI: 10.1186/s13037-024-00405-z

3. Cassera, M. A., Zheng, B., Martinec, D. V., Dunst, C. M. & Swanström, L. L. Surgical time independently affected by surgical team size. The American Journal of Surgery 198, 216–222 (2009). DOI: 10.1016/j.amjsurg.2008.10.016

4. Meyers, A. et al. Quantifying the impact of surgical teams on each stage of the operating room process. Front. Digit. Health 6, (2024). DOI: 10.3389/fdgth.2024.1455477

5. Hara, K. et al. Development of an estimation formula for preparation time of anesthesia induction and surgery accounting for clinical department factors in optimal surgery schedule management. Sci Rep 14, 25185 (2024). DOI: 10.1038/s41598-024-75631-7

6. Gupta, B., Agrawal, P., D’souza, N. & Soni, K. D. Start time delays in operating room: Different perspectives. Saudi J Anaesth 5, 286–288 (2011). DOI: 10.4103/1658-354X.84103

7. Al Amin, M., Baldacci, R. & Kayvanfar, V. A comprehensive review on operating room scheduling and optimization. Oper Res Int J 25, 3 (2024). DOI: 10.1007/s12351-024-00884-z

8. Sasano, N. et al. Time progression from the patient’s operating room entrance to incision: factors affecting anesthetic setup and surgical preparation times. J Anesth 23, 230–234 (2009). DOI: 10.1007/s00540-008-0713-4

9. Okeke, C. J. et al. Delay of Surgery Start Time: Experience in a Nigerian Teaching Hospital. Nigerian Journal of Surgery 26, 110 (2020). DOI: 10.4103/njs.NJS_61_19

Local anesthetics are essential pharmacological agents used in medical, surgical, and dental procedures to provide temporary loss of sensation while maintaining consciousness. Their administration must follow established guidelines regarding recommended doses to prevent systemic toxicity and adverse effects. The optimal dose and duration of action depend on the specific agent, route of administration, patient weight, metabolism, and whether a vasoconstrictor such as epinephrine is used to prolong efficacy. Clinicians must understand the maximum dose of local anesthesia that can be administered safely.

Bupivacaine, a long-acting agent used for local anesthesia, has a maximum recommended dose of 2.5 mg/kg without epinephrine and 3 mg/kg with epinephrine. Its prolonged duration of action, typically lasting between 3 to 9 hours, makes it ideal for procedures requiring extended pain relief. However, its cardiotoxicity at high doses remains a significant concern, as it has been associated with severe ventricular arrhythmias and cardiac arrest (1).

Lidocaine, one of the most commonly used local anesthetics, has a maximum recommended dose of 4.5 mg/kg without epinephrine and 7 mg/kg with epinephrine. It is characterized by a rapid onset of action and moderate duration, typically lasting 30 to 60 minutes when used for infiltration anesthesia, and up to 120 minutes when combined with epinephrine (2).

Mepivacaine, structurally similar to lidocaine, has a maximum recommended dose of 4.4 mg/kg without a vasoconstrictor and 6.6 mg/kg with levonordefrin. Its duration of action ranges from 45 to 90 minutes, making it a preferred choice for shorter dental and surgical procedures. Ropivacaine, a bupivacaine analog with reduced cardiotoxicity, has a maximum recommended dose of 3 mg/kg without epinephrine and 3.5 mg/kg with epinephrine. It provides prolonged analgesia with a lower risk of cardiac complications, making it ideal for epidural and peripheral nerve block procedures (3).

Procaine, one of the earliest synthetic local anesthetics, has a significantly higher maximum dose of 14 mg/kg due to its rapid hydrolysis by plasma esterases. Its short duration of action, typically 15 to 30 minutes, limits its use to minor procedures where prolonged anesthesia is unnecessary (4). Articaine, another common dental anesthetic, has a higher lipid solubility and rapid onset, allowing for effective pulpal anesthesia. Its maximum recommended dose is 7 mg/kg, and its duration of action is typically between 60 to 120 minutes when administered with epinephrine.

Toxicity from excessive doses of local anesthetic can lead to systemic complications, primarily affecting the central nervous system (CNS) and cardiovascular system. Early signs of toxicity include perioral numbness, tinnitus, dizziness, and muscle twitching. If untreated, toxicity may progress to seizures, respiratory depression, and cardiovascular collapse. The severity of these effects depends on factors such as the rate of systemic absorption, patient comorbidities, and concurrent drug interactions. Bupivacaine-induced cardiotoxicity is particularly difficult to manage due to its strong binding affinity to cardiac sodium channels. Recent advances in treatment, such as lipid emulsion therapy, have improved outcomes in cases of severe local anesthetic systemic toxicity (LAST), particularly with high-dose bupivacaine exposure (5).

Safe administration practices are critical to minimizing the risk of toxicity. Clinicians should use the lowest effective dose and administer the anesthetic gradually while monitoring for signs of intravascular injection. Aspiration prior to injection, slow administration, and proper patient positioning can reduce systemic absorption and decrease the likelihood of toxicity. In addition, advances in adjunct medications such as dexmedetomidine and clonidine have demonstrated efficacy in prolonging the duration of local anesthesia while reducing the required doses.

References

1. Rosenberg PH, Veering BT, Urmey WF. Maximum recommended doses of local anesthetics: a multifactorial concept. Reg Anesth Pain Med. 2004;29(6):564-524. doi:10.1016/j.rapm.2004.08.003
2. Moore PA, Hersh EV. Local anesthetics: pharmacology and toxicity. Dent Clin North Am. 2010;54(4):587-599. doi:10.1016/j.cden.2010.06.015
3. Yagiela JA. Local anesthetics. Anesth Prog. 1991;38(4-5):128-141.
4. Gunter JB. Benefit and risks of local anesthetics in infants and children. Paediatr Drugs. 2002;4(10):649-672. doi:10.2165/00128072-200204100-00003
5. Gitman M, Fettiplace MR, Weinberg GL, Neal JM, Barrington MJ. Local Anesthetic Systemic Toxicity: A Narrative Literature Review and Clinical Update on Prevention, Diagnosis, and Management. Plast Reconstr Surg. 2019;144(3):783-795. doi:10.1097/PRS.0000000000005989

When anesthesia providers administer anesthesia to relieve pain, relax and sedate patients, prevent movement during surgery, ensure that patients have no awareness or memory of procedures, or achieve a combination of those goals, anesthesia must be adjusted to the individual patient’s responses. Many factors affect how anesthesia affects different people, including differences associated with sex.

Sex, referring to the set of frequently consistent biological variables resulting from one’s chromosomal composition,¹ will be represented in dichotomy (i.e., “woman” or “man”) in this article. It is important to note that (1) at times, chromosomal composition and the resultant phenotype do not always match in a way consistent with typical patterns, (2) sexual chromosomal compositions are not limited to XX or XY, (3) sex and gender are separate concepts, the latter of which will not be addressed in this article, and (4) many prior scientific articles have conflated sex and gender; thus, this article will use only sex-based terms, though the data from which it is produced may have proxied gender for sex or vice versa.

Sexual dimorphism among humans extends to physiological differences that can affect the metabolism of volatile and intravenous anesthetics.² Some of these differences for women often include a smaller cardiac mass—estimated to be on average 15–30% smaller in women compared to men—lower lung volumes, a greater stress glucocorticoid response, and a greater sensitivity to baroreflex stimulation.²

Women on average have a greater volume of distribution for and clearance of the highly-lipophilic anesthetizing agent, propofol; therefore, greater doses are likely to be required for women when compared to men.³ Specifically, a 2003 study suggested that men might require a 30–40% reduction in the dose of propofol when compared to women.³

Additionally, for those who experience menstruation, progesterone, the predominant hormone during the luteal phase, can accentuate the effects of propofol through increases in cortical agonism of the gamma-aminobutyric acid type A (i.e., GABA-A) receptor functioning.^4,5 As such, one study demonstrated that propofol requirements for loss of eyelash reflex—an estimate of loss of consciousness—and time for bispectral index—a proprietary tool used for measuring the degree of consciousness—to reach 50 were found to be statistically significantly the least and shortest, respectively, for participants currently in the luteal phase. In other words, study participants in the luteal phase were more sensitive to propofol than participants in other menstrual phases.

Similar non-human animal studies have supported the existence of sex-mediated physiological differences in the metabolism of and response to volatile anesthesia. In a 2024 study using mice, researchers demonstrated that female mice regained consciousness and sentience more quickly following anesthetic exposure, demonstrated through observation of neuronal activity within sleep-promoting regions of the ventral hypothalamus.  Thus, it was discovered that female mice regain consciousness at a faster rate than their counterparts.⁶ This sexual dimorphism is hypothesized to be mediated by differential concentrations of testosterone, which produces increased sensitivity to anesthesia.⁶ The role of testosterone in increasing sensitivity to volatile anesthetics was further supported when the administration of letrozole, an aromatase inhibitor which prevents the conversion of testosterone to estrogens, diminished anesthetic sensitivity.⁶

Data suggest that physiological sex differences in humans extend to differing responses to volatile and intravenous anesthesia. On average, women tend to be more resistant to the sedating effects of anesthetics, largely mediated by a larger volume of distribution for lipophilic anesthetics, as well as by the estrogenic protective effects on the regions of the hypothalamus responsible for consciousness and awakening.

References

1. Johnson JL, Repta R. Sex and Gender: Beyond the Binaries. In: Designing and Conducting Gender, Sex, & Health Research. SAGE Publications, Inc.; 2012:17-38. doi:10.4135/9781452230610.n2

2. Filipescu D, Ştefan M. Sex and gender differences in anesthesia: Relevant also for perioperative safety? Best Pract Res Clin Anaesthesiol. 2021;35(1):141-153. doi:10.1016/j.bpa.2020.12.006

3. Pleym H, Spigset O, Kharasch ED, Dale O. Gender differences in drug effects: implications for anesthesiologists. Acta Anaesthesiol Scand. 2003;47(3):241-259. doi:10.1034/j.1399-6576.2003.00036.x

4. Bitran D, Purdy RH, Kellog CK. Anxiolytic effect of progesterone is associated with increases in cortical alloprenanolone and GABAA receptor function. Pharmacol Biochem Behav. 1993;45(2):423-428. doi:10.1016/0091-3057(93)90260-Z

5. Liu YW, Zuo W, Ye JH. Propofol stimulates noradrenalin-inhibited neurons in the ventrolateral preoptic nucleus by reducing GABAergic inhibition. Anesth Analg. 2013;117(2):358-363. doi:10.1213/ANE.0b013e318297366e

6. Wasilczuk AZ, Rinehart C, Aggarwal A, et al. Hormonal basis of sex differences in anesthetic sensitivity. Proc Natl Acad Sci. 2024;121(3):e2312913120. doi:10.1073/pnas.2312913120

Fiberoptic intubation (FOI) is a valuable technique for managing difficult airways in both anticipated and unanticipated scenarios. This method allows for direct visualization of the airway anatomy and precise placement of the endotracheal tube, making it particularly useful in patients with challenging airway characteristics. FOI can be performed on awake or anesthetized patients, with the awake technique being preferred for those with anticipated difficult airways. This article reviews the uses of fiberoptic intubation and the steps involved with the procedure.

The procedure begins with thorough patient preparation. Equipment, including the flexible fiberoptic bronchoscope, endotracheal tube, lubricant, and suction, is assembled. The patient is positioned either supine or seated, and standard airway and emergency equipment are made available. An antisialagogue, such as glycopyrrolate, may be administered if not contraindicated in order to reduce saliva flow. Supplemental oxygen is provided to ensure adequate oxygenation throughout the procedure.

Topical anesthesia is a crucial piece of the steps in fiberoptic intubation, especially for awake patients. This typically involves nebulizing lidocaine to anesthetize the oropharynx, applying lidocaine gel to the nasal passages if using a nasal approach, and spraying lidocaine to the posterior pharynx and larynx. Thorough topical anesthesia enhances patient comfort and cooperation during the procedure.

The actual intubation process involves several steps when using fiberoptic equipment. First, the bronchoscope is inserted through the nose or mouth. It is then carefully advanced while identifying anatomical landmarks. The vocal cords and tracheal rings are visualized, and additional local anesthetic may be sprayed through the scope as needed. The scope is passed through the vocal cords into the trachea, followed by advancing the endotracheal tube over the bronchoscope. Tube position is confirmed visually and with end-tidal CO2 monitoring. Finally, the bronchoscope is removed while holding the tube in place, and the tube is secured and connected to the ventilator.

FOI has various clinical applications. It is particularly useful in patients with limited mouth opening, cervical spine instability, airway tumors or masses, obesity with sleep apnea, and facial trauma or burns. The technique can be performed nasally or orally, with the nasal approach being advantageous in cases of large tongue, limited mouth opening, or when an unobstructed surgical field is beneficial.

While FOI is generally safe, it is not without potential complications. These may include difficulty navigating through secretions or blood, patient anxiety or intolerance of the procedure (in awake cases), equipment malfunction, and nasal bleeding when using the nasal approach. More serious complications, though rare, can include laryngospasm, bronchospasm, and oversedation leading to respiratory depression or airway obstruction. There is also a risk of trauma to airway structures and aspiration, particularly if laryngeal reflexes are compromised. Fiberoptic intubation is a highly useful tool for airway management but requires multiple steps, meaning that other techniques, such as direct laryngoscopy, may be preferred in straightforward cases.

The success of FOI relies on thorough preparation, appropriate patient selection, and skilled execution. As with any advanced airway technique, regular practice and ongoing education are crucial for maintaining proficiency. When the steps are performed correctly, fiberoptic intubation provides a safe and effective method for securing the airway in a wide range of clinical scenarios.

References

1. Collins SR, Blank RS. Fiberoptic intubation: an overview and update. Respir Care. 2014 Jun;59(6):865-78; discussion 878-80. doi: 10.4187/respcare.03012. PMID: 24891196.

2. Calder I. Murphy P. A fibre-optic endoscope used for nasal intubation. Anaesthesia 1967; 22: 489-91. Anaesthesia. 2010 Nov;65(11):1133-6. doi: 10.1111/j.1365-2044.2010.06535.x. PMID: 20946391.

3. Practice guidelines for management of the difficult airway. A report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 1993 Mar;78(3):597-602. PMID: 8457062.

4. Geffin B. Anesthesia and the “problem upper airway”. Int Anesthesiol Clin. 1990;28(2):106-114. PMID: 10604785.

5. Rosenberg PH, Heinonen J, Takasaki M. Lidocaine concentration in blood after topical anaesthesia of the upper respiratory tract. Acta Anaesthesiol Scand. 1980 Apr;24(2):125-8. doi: 10.1111/j.1399-6576.1980.tb01519.x. PMID: 7386144.

Anesthesiology is a critical branch of medicine focused on the relief of pain and the administration of anesthetics for surgeries, diagnostics, and therapeutic procedures. Many medical specialties rely on anesthesiology to ensure patient safety and optimal outcomes across diverse medical scenarios.

Surgery has a very close relationship with anesthesiology. Anesthesiologists manage the patient’s level of consciousness, pain, and vital functions during surgery, allowing surgeons to focus on the procedure itself. The anesthesiologist monitors the patient’s blood pressure, heart rate, oxygen levels, and other critical indicators. They also tailor anesthesia plans to meet the specific requirements of each surgery type, ensuring that the patient remains stable and comfortable from start to finish 1–3. Many different surgical specialties depend on anesthesiology.

In obstetrics, anesthesiologists play a significant role, particularly in pain management for labor and delivery. They frequently administer epidurals, a type of regional anesthesia that provides effective pain relief while allowing the mother to remain awake and responsive. Anesthesiologists are also essential in managing high-risk pregnancies or emergency situations that may require cesarean sections. In these cases, they ensure that the mother remains safe and pain-free during the procedure, while coordinating with obstetricians to facilitate a smooth delivery 4–6.

Cardiologists and anesthesiologists work together on a variety of non-surgical heart procedures. Anesthesiologists prepare patients for procedures like transesophageal echocardiograms or cardiac ablation by administering sedation or anesthesia and monitoring the heart’s response throughout the intervention 7,8.

Anesthesiologists frequently collaborate with gastroenterologists for diagnostic and therapeutic procedures, such as endoscopies, colonoscopies, and esophageal dilation. These procedures often require sedation to ensure patient comfort and cooperation, particularly in cases of anxiety or where movement needs to be minimized. Anesthesiologists assess each patient’s medical history and adjust the sedation plan based on individual needs, helping gastroenterologists perform these procedures effectively and safely 9,10.

The two specialties of anesthesiology and critical care are strongly related. Anesthesiologists are vital in intensive care units (ICUs), where they assist in managing patients with life-threatening conditions. Many anesthesiologists receive additional training in critical care, making them adept at handling ventilators, monitoring critical parameters, and providing sedation or pain relief to patients who require prolonged care. They work alongside pulmonologists, intensivists, and other ICU specialists, ensuring patients in critical condition receive the most effective and individualized care 11,12.

Anesthesiology is an interdisciplinary field that touches and collaborates with many different medical specialties. The skill set of anesthesiologists, which includes airway management, anesthesia and sedation, pain management, and rapid rescue interventions, is highly beneficial to many clinical situations.

References

1. Goyal, R. Surgeons and anesthesiologists: Need to communicate? J. Anaesthesiol.

Clin. Pharmacol. 29, 297 (2013). doi: 10.4103/0970-9185.117040

2. Cooper, J. B. Critical Role of the Surgeon–Anesthesiologist Relationship for Patient Safety. Anesthesiology 129, 402–405 (2018). doi: 10.1097/ALN.0000000000002324.

3. Anesthesiologist-Surgeon Relationships | Journal of Ethics | American Medical Association. https://journalofethics.ama-assn.org/issue/anesthesiologist-surgeon-relationships.

4. Toledano, R. D., Kodali, B.-S. & Camann, W. R. Anesthesia Drugs in the Obstetric and Gynecologic Practice. Rev. Obstet. Gynecol. 2, 93 (2009).

5. Apfelbaum, J. L. et al. Practice Guidelines for Obstetric AnesthesiaAn Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology. Anesthesiology 124, 270–300 (2016). doi: 10.1097/ALN.0000000000000935

6. Obstetric and Gynecologic Anesthesia | ScienceDirect. https://www.sciencedirect.com/book/9780323024204/obstetric-and-gynecologic-anesthesia.

7. Hayman, M., Forrest, P. & Kam, P. Anesthesia for interventional cardiology. J. Cardiothorac. Vasc. Anesth. 26, 134–147 (2012). DOI: 10.1053/j.jvca.2011.09.004

8. Society of Cardiovascular Anesthesiologists (SCA). https://scahq.org/.

9. Goudra, B. & Singh, P. M. Anesthesia for gastrointestinal endoscopy: A subspecialty in evolution? Saudi J. Anaesth. 9, 237 (2015). doi: 10.4103/1658-354X.154691

10. de Villiers, W. J. S. Anesthesiology and gastroenterology. Anesthesiol. Clin. 27, 57–70 (2009). doi: 10.1016/j.anclin.2008.10.007.

11. Bhattacharya, P. K., Nair, S. G., Kumar, N., Natarajan, P. & Chhanwal, H. Critical care as a career for anaesthesiologists. Indian J. Anaesth. 65, 48 (2021). doi: 10.4103/ija.IJA_1490_20

12. Hanson, C. W. et al. The Anesthesiologist in Critical Care MedicinePast, Present, and Future. Anesthesiology 95, 781–788 (2001). doi: 10.1097/00000542-200109000-00034.