The hormonal, physiologic, and anatomic changes of pregnancy have a number of significant anesthetic implications, including the potential for difficulties and failures in tracheal intubation.1 Recent advances in airway management algorithms, education, and devices (e.g. laryngeal mask airway, videolaryngoscopy instruments) have significantly reduced the morbidity and mortality associated with obstetric airway instrumentation and ventilation.2,3 Case fatality rates during general anesthesia for cesarean delivery in the United States decreased from 16.8 per million in 1991 to 1996 to 6.5 per million in 1997 to 2002.4 Confidential enquiries into maternal deaths in the United Kingdom observed a similar reduction in airway-related maternal deaths from 16 deaths in 1976 to 1978 to 6 deaths in 2000 to 2002.5
However, before these developments within the last 2 decades, obstetric anesthesiologists had few alternatives when performing direct laryngoscopy, mostly confined to the use of a different blade type (e.g., Miller or Macintosh) or size. In the late 1970s, Sanjay Datta, MBBS, developed a short laryngoscope handle to assist in the intubation of parturients. In this manuscript, we will chronicle the genesis and associated historical context of the Datta short laryngoscope handle.
After receiving his medical degree from the University of Calicut Medical School (Kozhikode, India), Dr. Datta matriculated to the Manchester Royal Infirmary (Manchester, United Kingdom) as an anesthesia registrar and later to McGill University (Quebec, Canada) as a research fellow in regional and obstetric anesthesia. In 1974, Dr. Datta was hired as an obstetric anesthesiologist at the Boston-Lying in Hospital (which would become the Brigham and Women’s Hospital in 1980), and in 1988, he became the Director of Obstetric Anesthesia. As a researcher, Dr. Datta observed a number of similarities, as well as differences, in the practice of obstetric anesthesia in Boston when compared with his prior experiences in Manchester and Montreal.
First, the incidence of cesarean deliveries appeared to be increasing, most dramatically within North America. From 1970 to 1978, the cesarean birth rate in the United States increased almost 3-fold, from 5.5% to 15.2%.6 This change was consistent with the practice at the Brigham and Women’s Hospital, where the primary and repeat cesarean delivery rates were 14% and 10% in 1981,7 as well as in all geographic regions of the United States, regardless of type of hospital, neonatal birth weight, or reimbursement sources.8–10 Similar increases were observed in Canada, where the cesarean delivery rate increased from 7.5% in 1972 to 13.9% in 1979.11 By contrast, in much of Europe, cesarean delivery rates remained in the single digits; at the National Maternity Hospital in Dublin, the cesarean delivery rate varied between 4% and 5% from 1965 to 1980.12
Second, cesarean deliveries were commonly performed under general anesthesia, and in some hospitals, this form of anesthesia was undergoing an increase in the frequency of use. A report from the Charlotte Memorial Hospital, North Carolina, indicated that in 1964, the anesthetic management for cesarean delivery consisted of general anesthesia 45% and spinal anesthesia 45%, with the remaining occurring under local infiltration.8 By 1974, the rates for general anesthesia at the same institution had increased to 88% of all cases, with only 11% being performed under spinal anesthesia and 1% under local infiltration. Similarly, a survey of maternity hospitals conducted in the United Kingdom revealed that 77% of cesarean deliveries were performed under general anesthesia in 1982.13
Although a growing recognition that infants born from mothers who underwent general anesthesia were more depressed than those born under regional anesthesia14 prompted a reduction in general anesthesia use, particularly at training institutions, the rates remained high. In a 1975 survey of 39 obstetric anesthesia training programs within the United States, Hicks et al.15 observed that 43% of cases were performed under general anesthesia, with the remainder under epidural anesthesia (32%), spinal anesthesia (24%), and local infiltration (1%). In 1979, Drs. Datta and Alper16 reported similar rates at the Brigham and Women’s Hospital with cesarean deliveries being performed under general (38%), epidural (26%), and spinal (36%) anesthesia. At the Winnipeg Women’s Hospital in Canada, the use of general anesthesia for cesarean delivery decreased from 32.9% of cases in 1975 to 12% in 1983.17
The continued application of general anesthesia for cesarean delivery likely persisted due to comfort with its use and concerns regarding regional anesthesia. In the 1960s and 1970s, cyclopropane, a nonpungent anesthetic drug that could be administered with a high percentage of oxygen, was an ideal drug for rapid mask inhalation and maintenance of anesthesia in the parturient.18 By contrast, in 1962 at 1 large labor and delivery unit within the United States, spinal anesthesia-induced hypotension was reported to occur in 24% of cesarean deliveries.8 Another U.S. survey performed in 1973 revealed that although anesthesiologists preferred regional over general anesthesia for obstetric cases, they were hesitant to use it because of lack of expertise.19 In addition, epidural labor analgesia, which offered the possibility for convenient and rapid conversion to cesarean delivery anesthesia, was not in widespread use. A survey performed in 1975 from the Winnipeg Women’s Hospital in Canada showed a 6% rate of epidural labor analgesia.16 A 1981 survey of obstetricians and anesthesiologists in the United States observed a 16% rate of epidural labor analgesia use,20 which was similar to the 17% rate reported in a survey conducted in the United Kingdom for the years 1982 to 1986.21 Finally, the absence of “in-house” or “on-call” anesthesia providers restricted access to regional labor analgesia. In 1981, although 62% of tertiary hospitals in the United States had an anesthesia provider assigned full time to labor and delivery, this occurred in only 3% to 6% of primary and secondary care centers.22 The range of epidural labor analgesia use can vary widely, even today, by geographic location, patient and provider beliefs, and availability of staff and resources.
Third, Dr. Datta perceived that parturients within North America had a higher body mass index (BMI) than in the United Kingdom. In nonpregnant patients in the 1970s, the incidence of obesity (BMI ≥30) was 14.1% and 12.7% of the population in the United States and Canada, respectively, as reported in the United States Center for Disease Control’s report23 and the Canadian Health Survey.24 By contrast, in the United Kingdom, the 1970s data from the National Obesity Observatory reported an incidence of obesity of <8%.25
Although a number of factors may have played a role in the increasing BMI in non-obstetric patients, the weight gain observed in parturients appears to have been promoted within the United States. Initially, significant weight gain was a cause for concern; in 1966, Williams Obstetrics, the major obstetrics textbook, stated: “excessive weight gain in pregnancy is highly undesirable for several reasons and it is essential to curtail the increment in gain to 12.5 kg at most or preferably to 6.8 kg.”26 However, a subsequent review in 1970 of the scientific evidence by the National Academy of Sciences concluded that the usual practice of restricting maternal weight gain was associated with increased risk of low birth weight. Therefore, the National Academy of Sciences committee on maternal nutrition increased the formal recommendation for pregnancy weight gain to 9 to 11.4 kg.27 When Dr. Datta arrived in Boston in the mid-1970s, these new weight gain recommendations were being realized (Fig. 1).
The implications of obesity on anesthetic management, and specifically intubation, were appreciated. Indeed, a meeting of the Royal Society of Medicine in 1968 opened with the concept that too many maternal deaths were due to anesthesia, and that obesity increased the risk: “endotracheal intubation could be extremely difficult in a fat woman…”29 A review on maternal deaths in Michigan from 1972 to 1984 revealed that unsuccessful tracheal intubation was one of the leading causes of death during that time;30 the majority of deaths were in individuals who were obese or undergoing general anesthesia for emergency cesarean delivery.
In addition to these obesity-related concerns, Dr. Datta also observed that the distribution of weight gain associated with pregnancy appeared to increase the risks of providing general anesthesia. Engorgement of the soft tissues of the oropharynx and enlargement of breast tissue during pregnancy appeared to make introducing the laryngoscope blade more difficult. Knowledge of the anatomical changes of pregnancy and the resultant increase in intubation difficulty were just beginning to be more fully appreciated when Dr. Datta developed his new handle. A postpartum “death by asphyxia” in an obese woman from an intubation failure reported in 1976 implicated the presence of anatomic “technical difficulties” and “limited professional skills” as the cause for demise.31 Another report from 1980 indicated 3 accounts of difficult intubation stemming from the laryngeal edema resulting from “strenuous bearing down efforts in the second stage of labor” and the generalized edema present in severe preeclampsia.32
The American Society of Anesthesiology closed claims database in the 1970s observed that maternal deaths were involved in 30% of all obstetrics claims, most stemming from difficulty with intubation or ventilation. In 1985, experiences within a busy maternity unit allowed the estimation that failed intubation was approximately 8 times higher in the obstetrical patients than among non-obstetrical patients, and the incidence of fatal failed intubation was 13 times higher in the obstetric population.33 While Dr. Datta did not personally experience any cases of maternal mortality related to failure of airway instrumentation or intubation during pregnancy, the persistent difficulties related to direct laryngoscopy led him to evaluate ways in which the laryngoscope itself could be altered.
A New Tool
The initial insertion of a laryngoscope during pregnancy can be difficult given the anterior expansion of the chest cavity34 and the increase in breast tissue, which can often advance in a cephalad direction while positioning for general anesthesia. Even when the laryngoscope is inserted with the handle directed to the right, the anatomic limitations presented by the chest wall and breasts could still be an impediment to rotation and manipulation of the laryngoscope. Dr. Datta believed these limitations could be minimized in 2 ways: one solution was to increase the angle between the laryngoscope handle and the blade. However, anesthesiologists were trained and comfortable with a handle/blade angle of 90°;35 moreover, increasing this angle could potentially create more dental trauma if the blade and handle were rotated to lift the tip of the laryngoscope blade. A second solution was to retain the 90° angle but to shorten the handle; this was the method pursued.
Dr. Datta sought the assistance of John Briwa, a talented and clever anesthesia technician. After much trial and error, Briwa adeptly cutoff the majority of a penlight laryngoscope handle and slipped it into the barrel of a 20-mL syringe long enough to hold a 4.05-V battery. A small wire was connected from the negative end of the battery to the light source, and 2 small screws with epoxy glue were used to hold the device together.36
A standard laryngoscope handle is approximately 6¼ in in length; Dr. Datta’s handle was shorter, at 4¼ in. The new modified short laryngoscope handle appeared to increase the ease and success of intubation in pregnant women for Dr. Datta and his colleagues; however, robust, standardized comparisons were not performed because of the limited number of prototypes. In hopes of sharing the invention, Dr. Datta entered an exclusive verbal agreement with the Foregger Company. Unfortunately, the company was focused on the development of a new anesthesia machine at the time, and the device was neither manufactured nor patented. In hopes of having the new device developed, Dr. Datta published news of the invention,33 and a number of anesthesia equipment companies began manufacturing their own versions of the short laryngoscope handle; several companies increased the diameter of the short handle to accommodate a larger battery (“C” or “R14” battery) and potentially increase the ease and security of the grip (Fig. 2). The requirement for smaller batteries with lower total voltage likely was the most observed disadvantage of the handle; Tousignant and Tessler36 indicated that compared with the regular sized handle, the short-handle laryngoscope produces a lower intensity light, thereby being a potential impediment to intubation.
A Lasting Impact
There are no nationally representative data with which to study trends in gestational weight gain within the United States.37 However, the prevalence of obesity among American women of childbearing age has more than doubled since 1976, so we can likely infer that the high BMI parturient will become increasingly common.33
Although there are more airway management devices and options, with even greater acceptance of laryngeal mask airway use for cesarean delivery,38,39 endotracheal intubation with laryngoscopy using conventional handles and blades remains a primary method of intubation for airway management for cesarean delivery. Recently, a prospective crossover study compared the effectiveness of a standard long-handle laryngoscope versus a short-handle laryngoscope on ease of intubation among individuals wearing protective sports equipment.40 The investigators found the use of the short-handle laryngoscope easier for physicians needing to intubate players on the field, wearing protective equipment while in-line cervical spine immobilization was maintained. Similarly, for the parturient, interference with the insertion and manipulation of the laryngeal blade during direct laryngoscopy occurs through physically present obstructions,41 which could be minimized by the use of a short laryngoscope handle (Fig. 3, A and B).
The short laryngoscope handle design, as introduced by Sanjay Datta, MBBS, has been produced by a number of manufacturers worldwide,42 has been clinically accepted throughout a spectrum of medical specialties, and is found in emergency airway carts, anesthesia carts, and operating rooms around the world.42 Too often, the story behind the development of a device and the complimentary historical context are not shared; we offer this recounting as a historical footnote and a method of inspiring others who desire to develop other devices, which ultimately may benefit the management and care of the obstetric patient and their offspring.
Name: Laura Y. Chang, MD.
Contribution: This author interviewed the original developer of the short-handle laryngoscope and prepared the manuscript.
Attestation: Laura Y. Chang has approved the final manuscript and attests to the integrity of the original data and the analysis reported in this manuscript.
Name: Lawrence C. Tsen, MD.
Contribution: This author edited the manuscript and is the corresponding author.
Attestation: Lawrence C. Tsen has approved the final manuscript and attests to the integrity of the original data and the analysis reported in this manuscript and is the archival author.
This manuscript was handled by: Steven L. Shafer, MD.
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