Over a 10-year period of being a solo anesthesiologist at a surgery center, I innovated a system of airway management for patients under deep sedation/total IV anesthesia (TIVA). It made use of a unique nasal continuous positive airway pressure (CPAP) interface connected to a circle circuit system incorporating a CPAP machine and monitored by a pretracheal stethoscope in the suprasternal notch.
It worked very well. Afterward I became an assistant professor in an academic program where I might promote my innovation and become famous. I was delusional: My patented interface could be trimmed to size with clippers, but I was advised that this trimming would not appeal to more sophisticated practitioners! After several wrong turns in the redesign process, money ran out. At that point I was old and frustrated; and so, I retired.
In a short time, I missed the work. In addition, my extravagant spending on prototypes, lawyers and gourmet dining drove me to find a part-time job. After starting at a new surgery center, I was informed by the manager that a nationwide shortage of propofol was imminent and that I needed to find another way to induce general anesthesia.1 Sodium thiopental (Pentothal), meanwhile, had been removed from the market because of its use in capital punishment!2 This added to my perplexity because, without thinking much about what it might be called, I had, in effect, become totally devoted to those anesthetic strategies commonly known as “balanced,” “multimodal” or “TIVA” for most of my career of 40-plus years.3 I reserved volatile agents for children and equated the newer agents with the older agents from my training in 1970.
In my mind, halothane and methoxyflurane (Penthrane) were to be avoided whenever possible. Nevertheless, when used out of necessity, sevoflurane and isoflurane with mask induction always worked very well in children.4,5 And so, why not treat adults like children?
Timid at first, I soon observed that mask inductions with sevoflurane and nitrous oxide were even quicker and easier in adults.6 I found sevoflurane in higher concentrations—doses that I would have instinctively avoided in the past—to be gently suppressing to the heart and blood pressure, both of which responded nicely to the usual remedies.7 The switch to isoflurane for maintenance was less suppressing, less expensive, less metabolized, and it wore off almost as quickly.
To start, the circuit was pre-charged with 8% sevoflurane in a 50/50 mixture of nitrous oxide and oxygen. I then used a mask and generated CPAP by increasing gas flows as high as needed to keep the reservoir bag distended and the airway open. This was confirmed by a pretracheal stethoscope. The stethoscope was absolutely necessary because excess gas is discharged through the mouth and not necessarily through the circuit, where carbon dioxide would usually be detected. I never needed an airway to maintain patency, and the patient was deep enough within a few minutes to insert a laryngeal mask airway into the pharynx or the tip of a curved blade into the vallecula to visualize the vocal cords.
Topical anesthesia from a laryngotracheal topical anesthesia kit prior to the insertion of an endotracheal tube (ET tube) causes a short-lived laryngospasm but facilitates quiet breathing for the remainder of the anesthetic. Moreover, if the anesthesia is deepened and the respirations are controlled, adequate relaxation without the need of a muscle relaxant can be obtained for most outpatient procedures. I never have to suction secretions, neither at the beginning nor the end, because I insert and remove all devices under anesthesia that is deep enough to avoid that. CPAP is applied immediately during emergence to maintain patency for the few minutes that it may take for pharyngeal muscle tone to re-form the upper airway.
To fill in the gaps in the description of my current practice, let me add:
Just before entering the OR, I give a mixture of midazolam and small preemptive doses of antiemetics mixed with an anticholinergic. Patients are very cooperative and usually have no recollection of the actual induction.
No narcotics are used during anesthesia. If the anesthesia needs to be deepened, the vaporizer is dialed up to the max and the flow rates increased to flush in the highest concentration. This is comparable to administering something intravenously. Patients emerge quickly, and nausea does not occur except very rarely when a narcotic is given in the PACU without a preemptive boost of an antiemetic.
I rarely give anything intravenously during an inhalational anesthetic, other than vasopressors. I use a muscle relaxant—but never succinylcholine—only to prevent an obturator jerk during a TUR-BT (transurethral resection of a bladder tumor).8
Personal Experiences
I know that the foregoing description is replete with absolute statements, and that the reader might reject pronouncements that say or imply “always” or “never.” However, I know what works well in my hands. And I wish to be as emphatic as those lesser experienced experts who must cite studies to prove their bias. In fact, due to my age and my solo years in practice, I have more personal experience than most with the practical aspects of inhalational anesthesia and airway management.
As a toddler in the 1940s, I had three surgeries under ether anesthesia, with spontaneous respirations and no ET tube. The first two surgeries were an inguinal hernia repair and an appendectomy by Dr. “Button-Hole” Cox, who was so renowned for his tiny incisions that no one can today recall his real name. Then came a tonsillectomy done on a kitchen table in the basement office of my family doctor’s home. This became my earliest and most vivid memory: being held down by two big guys while Dr. Nicholson dropped ether onto a gauze-covered tea strainer held over my face. Thank goodness midazolam was not available at the time or I would have no nostalgia to share!
I was the firstborn. My parents calmed down after me, and none of my eight siblings ever had anesthesia during their childhood. This is reflected in their higher IQs and gives credence to the detrimental effect of volatile anesthetics on the brain.
During my anesthesia residency, I was one of the last residents privileged to administer ether to children undergoing a tonsillectomy. We finessed induction by using halothane in the induction room. Then, when the child was deep enough, we would rush to the OR and insufflate ether through an “ether hook” placed at the corner of the mouth. The surgeons insisted that an ET tube would be in their way as they used “stick ties” (a ligature on the end of a right angle clamp) to control the bleeding. Once underway, my job was to assist with a tonsil-tip suction. It was very messy. Nevertheless, we didn’t worry about breathing or aspiration because the dramatic sputtering and coughing constantly reassured us that the patient’s own self-defenses were very functional under surgical anesthesia.
Shortly after finishing my pediatric rotation, electrocautery came into vogue. Sadly, the stick tie was abandoned, and ether became a full-blown fire hazard. Halothane through a “halothane hook” could have been used, but it would have been tricky and expensive.
The quicker transitions between Guedel’s stages of anesthesia probably could be monitored with the newer volatile anesthetics, if one could find a patient not under the influence of oral and IV medications. Nevertheless, I still monitor the eye signs. I have also observed that:
- the vomiting reflex disappears early on;
- the laryngeal reflex remains with spontaneous respirations down to deep levels of anesthesia;
- CPAP opposes reflux8; and
- continuous stethoscope monitoring of the upper airway is the earliest detector of potential aspiration9 and the need for suction.
Keep in mind that ether, with its preservation of respirations and protective airway reflexes, has been used safely in recent years for emergency cesarean deliveries in third-world countries.10 It can be manufactured simply and affordably by a local apothecary and administered by new obstetrics trainees. One limiting factor to its wider use is the lack of experienced anesthesiologists to teach the method.11,12
I relate none of the significant anesthesia complications that I have witnessed during my lengthy career to the use of sevoflurane and isoflurane.13 Rather, all of my bad experiences are associated with combinations of IV medications.14
My statistics are obviously skewed. Nevertheless, there is a reason that rapid sequence inductions were originally called “crash” inductions,15 and there is no professional terror greater than hearing, “can’t intubate, can’t ventilate!”16 Yet, when the stomach has not been distended and pressurized by too vigorous an attempt to bag the paralyzed patient, I have observed how infrequently stomach contents appear in the pharynx after a smoothly successful rapid sequence intubation.
One might wonder whether it is always worth it to take away the patient’s own very effective self-defense mechanisms in a risky attempt to control a crisis that might not materialize. Likewise, one might question the dictum to never start an emergency inhalational anesthetic without, first, establishing IV access.17 Times have changed: In the 1940s, general practitioners carried ether in their doctor’s bag just in case a victim needed to be painlessly extracted from a car accident. Are we now too sophisticated to use the earliest and most basic tools of our profession: the inhalational induction and maintenance of anesthesia?
In Conclusion
Especially in adult patients, every anesthesia provider should be proficient with total inhalational induction and maintenance of anesthesia.18,19 A standard face mask can be used or an anesthesia-specific nasal CPAP mask, which is now commercially available.20 The techniques are slightly different but well worth mastering. Also, continuous monitoring of upper airway breath sounds works where the carbon dioxide monitor fails.21
The short video demonstrates a new technique of mask induction of anesthesia.
In any case, an optimized inhalational anesthetic in the adult patient has unique advantages and should be considered as a worthy option alongside balanced, multimodal or TIVA methods.
Dr. Noble reported that he no longer has any relevant financial disclosures. Editor’s note: The views expressed in this article belong to the author and do not necessarily reflect those of the publication.
References
- Hvisdas C, Lordan A, Pizzi LT, et al. US propofol drug shortages: a review of the problem and stakeholder analysis. Am Health Drug Benefits. 2013;6(4):171-175.
- ASA statement on sodium thiopental’s removal from the market [press release]. January 21, 2011. www.asahq.org/ about-asa/ newsroom/ news-releases/ 2011/ 01/ asa-statement-on-thiopental-removal-from-the-market. Accessed April 2, 2019.
- Brown EN, Pavone KJ, Naranjo M. Multimodal general anesthesia: theory and practice. Anesth Analg. 2018;127(5):1246-1258.
- Bovill JG. Inhalation anaesthesia: from diethyl ether to xeon. Handb Exp Pharmacol. 2008;(182):121-142.
- Zielinska M, Holtby H, Wolf A. Pro-con debate: intravenous vs inhalation induction of anesthesia in children. Paediatr Anaesth.2011;21(2):159-168.
- Van den Berg AA, Chitty DA, Jones RD, et al. Intravenous or inhaled induction of anesthesia in adults? An audit of preoperative patient preferences. Anesth Analg. 2005;100(5):1422-1424.
- Sato J, Saito T, Takahashi T, et al. Sevoflurane and nitrous oxide anaesthesia suppresses heart rate variabilities during deliberate hypotension. Eur J Anaesthesiol. 2001;18(12):805-810.
- Kerr P, Shoenut P, Millar T, et al. Nasal CPAP reduces gastroesophageal reflux in obstructive sleep apnea syndrome. Chest. 1992;101(6):1539-1544.
- Guedel AE. Stages of anesthesia and re-classification of the signs of anesthesia. Anesth Analg. 1927;6(4):157-162.
- Maltby JR, Malla DS, Dangol H. Open drop ether anaesthesia for caesarean section: a review of 420 cases in Nepal. Can Anaesth Soc J. 1986;33(5):651-656.
- Chang CY, Goldstein E, Agarwal N, et al. Ether in the developing world: rethinking an abandoned agent. BMC Anesthesiol. 2015;15:149.
- Schaut DJ, Khona R, Gross JB. Sevoflurane inhalation induction for emergency cesarean section in a parturient with no intravenous access. Anesthesiology. 1997;86(6):1392-1394.
- McClelland SH, Hardman JG. Inhalational induction of anaesthesia in adults: time for a breath of fresh air? Anaesthesia. 2007;62(11):1087-1089.
- O’Rourke M, Schmidt ES, Metry JE, et al. Delayed respiratory depression secondary to opioid overdose after multimodal analgesia with transverse abdominis plane blocks in postanesthesia care unit: a case report. A A Pract. 2018;10(7):182-184.
- Woodbridge PD. “Crash induction” for tracheal intubation. JAMA. 1967;202(8):845.
- Troop C. Difficult intubation in the obese patient. APSF Newsletter. 2005;20(4):83.
- Schaut DJ, Khona R, Gross JB. Sevoflurane inhalation induction for emergency cesarean section in a parturient with no intravenous access. Anesthesiology. 1997;86(6):1392-1394.
- Smith TE, Elliott WG. Routine inhaled induction in adults: a safe practice? Anesth Analg. 2006;102(2):646-647.
- Muzi M, Robinson BJ, Ebert TJ, et al. Induction of anesthesia and tracheal intubation with sevoflurane in adults. Anesthesiology. 1996;85(3):536-543.
- Cataldo SH, Mondal S, Lester LC, et al. Using the SuperNO2VA device on a patient with a known difficult airway: a case report facilitating fiberoptic intubation and postoperative nasal positive pressure. A A Pract. 2019;12(5):160-164.
- Martinez MJ, Siegelman L. The new era of pretracheal/precordial stethoscopes. Pediatr Dent. 1999;21(7):455-457.