1

Introduction

General anesthesia is administered to obstetric patients with an incidence of 1–2% for non-obstetric procedures [ ] and up to 6 % for caesarean deliveries [ ]. Difficult airways pose a significant risk of mortality due to intubation complications, accounting for over half of anesthetic-related deaths related to airway issues [ ]. This highlights the need to review and refine the techniques used by anesthesiologists. Increased difficulty in obstetric airway management is primarily attributed to physiological factors, such as reduced Functional Residual Capacity [ ], anatomical factors, including fluid retention, airway edema [ ], neck anatomical variations, and a shift in Mallampati (MP) scores to MP III and IV [ , ]. Failed intubation and inadequate oxygenation can lead to death, emphasizing the importance of proper organization, judgment, and oxygenation during general anesthesia, with a mortality rate of approximately one death per 90 failed intubations [ ].

Concerns regarding managing obstetric airways frequently involve a perceived lack of competency among residents and junior staff [ ]. Due to the preponderant indication of neuraxial anesthesia in this group of patients, and considering that airway management is mainly performed in emergencies, most practitioners have few training opportunities in the management of the airway of these patients to acquire sufficient experience [ ].

Guidelines have been developed to manage difficult airways, including maintaining oxygenation and managing failed intubation or oxygenation cases [ ]. The 2015 Difficult Airway Society’s updated guidelines recognized the efficacy of video laryngoscopy for difficult intubation cases and recommended training and access to such devices for all anesthetists [ ]. The Canadian Airway Focus Group also recommends video laryngoscopy for tracheal intubation in general and obstetric patients, citing reduced complications and improved success rates [ ]. Randomized controlled trials comparing video laryngoscopy to direct laryngoscopy in the general population surgical patients with predicted difficult airways have reported improvements in laryngeal view and frequency of successful intubations [ ]. Therefore, substantial evidence exists in the general population to support the utility of video laryngoscopy in reducing failed intubation risk and complications associated with intubation [ ].

Similar recommendations for video laryngoscopy have been extended to obstetric anesthesia. The Difficult Airway Society and the Obstetric Anaesthetists’ Association recommend the universal adoption of video laryngoscopy for general obstetric anesthesia cases, consistent with their recommendations for the general population. However, it should be noted that these recommendations are primarily based on expert advice, and evidence within the obstetric population is still lacking [ ].

In early 2015, Scott-Brown and Russell published a review on video laryngoscopes and the obstetric airway [ ]. This review discussed the types of video laryngoscopes available at that time use of these devices on the non-obstetric and obstetric population. The review had only a brief literature review on the obstetric population as, at the time, only case reports, one observation study, and one randomized clinical trial had been published on the topic. Since then, other studies have been published, generating a more comprehensive picture of the use of video laryngoscopes in the obstetric population. Video laryngoscopy has been established as an important tool for managing airways since 2015, with some experts advocating its use as the primary option in pregnant patients. This scenario sets the stage for a revised narrative review on the topic.

The objective of this narrative review was to provide an analysis of the literature regarding the performance and efficacy of video laryngoscopy in obstetric patients. This review aims to summarize the current evidence on using video laryngoscopy as a tool for airway management in the obstetric population, including its benefits, limitations, and potential impact on patient outcomes. Additionally, this review sought to identify gaps in knowledge, areas for further research, and recommendations for the widespread adoption of video laryngoscopy in obstetric anesthesia. This review aimed to enhance clinical practices and improve patient safety in obstetric airway management by exploring the evolving role of video laryngoscopy in obstetrics.

2

Methods

3

Review of literature

Video laryngoscopy has been used since 2001, with early evidence to suggest its efficacy in difficult airways or failed intubation attempts in the general population [ ]. Scott-Brown and Russell commented on several contributing factors to increased difficult airways in obstetric patients, including anatomical factors such as weight gain and fluid retention during pregnancy, as well as acute airway changes during labor and delivery [ , ]. Advancements in guidelines have also been made to better manage patients with difficult airways and to provide emergent airway management and oxygenation during intubation attempts. However, the authors pointed out the limitations of using only a supraglottic airway device to rescue difficult airways and suggested the use of alternative laryngoscopes, such as a video laryngoscope. Improvements include better glottis visualization, increased success rate in patients with predicted difficult airways, and availability as a rescue technique [ , ]. Limitations included potentially increased time to intubate, a larger diameter of the laryngoscopy device causing potential trauma to the mucosa, and the training required to gain proficiency in using this new laryngoscope [ , ]. A scarcity of evidence, particularly in the obstetric population, makes video laryngoscopy still an area of investigation for its role as either a primary means to intubate or as a rescue following failed intubation attempts in obstetric patients [ ].

Aziz et al. published an observational retrospective study on obstetric patients undergoing general anesthesia cases. The authors reviewed both devices’ use and effectiveness during three years on their institution’s obstetric floor. They reported that out of 180 total intubations measured over this time period, video laryngoscopy’s first attempt was successful in 18 out of 18 intubation events [ ]. Conversely, direct laryngoscopy had a lower first-attempt success rate: 157 out of 163 intubations. One failed direct laryngoscopy intubation was subsequently rescued by video laryngoscopy. The authors interpreted their findings to support an adequate laryngeal view by using both direct and video laryngoscopes. Additionally, the authors supported the pre-emptive use of video laryngoscopy in patients with predicted difficulty in intubation, including a higher MP score, lower mouth opening distance, or short thyromental distance.

Arici et al. [ ] compared the McGrath series 5 video laryngoscope to the Macintosh direct laryngoscope in a randomized controlled study with 80 obstetric patients undergoing elective caesarean sections. All intubations were performed by an experienced anesthesiologist with a 100 % success rate on the first attempt. Furthermore, all surgeries were completed without complications, and no palatoglossal arch or dental injuries occurred. The time to intubation with video laryngoscopy was significantly longer than that with direct laryngoscopy, whereas the percentage of glottic opening was significantly higher with video laryngoscopy.

A randomized controlled trial by Amini and Shakib [ ] examined 70 obstetric patients undergoing elective caesarean section and compared intubation using a direct laryngoscope with intubation using a video laryngoscope. The study found modest benefits of video laryngoscopy in terms of hemodynamic factors within the first 3 min following intubation and no difference in the fourth and fifth minutes. Additionally, there were no significant differences in time to intubation, sore throat incidence, or neonatal APGAR scores between the two groups.

Krom et al. performed systematic reviews on studies comparing the effectiveness of video laryngoscopy in obstetric patients compared to other anesthetic methods in category-1 caesarean section in patients with anticipated difficult tracheal intubation [ ]. This study was performed following The Obstetric Anesthetist’s Association and The Difficult Airway Society guidelines, which endorsed the availability of video laryngoscopy in all obstetric cases [ ]. Previous investigations have also suggested that video laryngoscopy should replace awake fiberoptic intubation in difficult airway situations [ , , ]. The authors commented on the importance of timely intervention, which is a potential disadvantage for spinal anesthesia or flexible scope intubation. General anesthesia plus rapid sequence induction using a video laryngoscope was compared to awake flexible scope intubation plus general anesthesia and spinal anesthesia. After performing a systematic review of each option, the authors reported that general anesthesia plus rapid sequence induction would provide a faster induction time than the other two methods, with an estimated risk of failed airway control after rapid sequence induction of 21 per 100,000 cases. The authors interpreted the use of video laryngoscopy in anticipated difficult airways to be a suitable option for obstetric patients undergoing a category-1 caesarean section with a small yet significant risk of death.

In obstetric anesthesia cases, there is additional concern regarding the time to intubation, which may be prolonged when using a novel laryngoscope as part of the intubation process. Blajic et al. performed a randomized controlled trial in 180 obstetric patients undergoing elective and urgent caesarean section, comparing the efficacy of two video laryngoscopes (C-MAC and King Vision) as well as a direct laryngoscope [ ]. There were no significant differences between any treatment group in terms of time to intubate, nor was there any significant change in the difficulty of intubation. The authors concluded that video laryngoscopy was a suitable primary device for intubation in obstetric patients.

Toker et al. performed a randomized controlled trial in 100 patients to compare direct laryngoscopy versus video laryngoscopy for obstetric patients undergoing elective caesarean section requiring general anesthesia [ ]. The authors were interested in investigating the time to intubate and glottis visualization during intubation. Video laryngoscopy in this sample population produced significantly faster intubation time than direct laryngoscopy, along with a significantly improved glottic view, as measured by Cormack-Lehane and percentage of glottic opening (POGO) grading. The hemodynamic response to intubation, a secondary outcome of the study, was also significantly reduced by video laryngoscopy, as shown by a lower mean arterial pressure and heart rate following intubation compared to direct laryngoscopy. The authors interpreted these favourable outcomes in terms of video laryngoscopy being able to better navigate the anatomical and physiological changes that occur during pregnancy that would otherwise complicate intubation.

A recent meta-analysis was performed by Howle et al. to assess whether video laryngoscopy provided any significant benefit compared to direct laryngoscopy in obstetric patients [ ]. Case reports analyzed by the authors suggest improved glottis visualization and greater success in patients with difficult airways. Cross-sectional studies assessing difficult intubation have demonstrated success when video laryngoscopy was used as a rescue technique. A simulation trial with anesthetists randomly assigned to video or direct laryngoscopy showed an increased rate of successful intubation in simulated difficult obstetric airways when video laryngoscopy was used. Randomized controlled trials showed no significant difference between direct and video laryngoscopes for the first-attempt success rate or time to intubation. In contrast to previous studies, there was no difference in the perceived difficulty of intubation or hemodynamic changes following intubation. However, the authors recognize that the study was underpowered, as only 417 intubations were included, and a minimum of 800 would be needed to attain statistical significance. The authors commented on promising cases of video laryngoscopy being successfully used in recognized difficult airways and as a rescue technique following failed direct laryngoscopy intubation.

Zasso et al. [ ] performed a single-center retrospective review analyzing caesarean sections performed under general anesthesia in a before-after Coronavirus Disease-2019 pandemic period. They were able to analyze data from 153 patients in the before period from January 2018 to February 2020 and 137 in the after period from March 2020 to March 2022. The study aimed to compare the utilization rate of video laryngoscopy versus direct laryngoscopy as the primary device for intubation before and after COVID-19 as the primary outcome. Additionally, the authors collected the first-pass success, Cormack-Lehane view, and perceived difficult intubation as secondary outcomes. The retrospective review observed a substantial increase in the use of video laryngoscopy compared with direct laryngoscopy in their sample size. Regardless of the increased utilization of video laryngoscopy during the pandemic, the study was not able to show significant difference in the first-pass success. The study also reported better glottic visualization and more perceived difficulty for intubation with video laryngoscopy. The authors concluded that the pandemic triggered a significant increase in the use of Video Laryngoscopy.

The most recent randomized, double-blind clinical trial was performed in 2024 by Honarmand et al. [ ]. The study recruited 90 patients for caesarean section under general anesthesia. The patients were divided into two groups consisting of intubation performed using direct laryngoscopy or video laryngoscopy (GlideScope®). The study collected hemodynamic parameters such as systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, saturation of peripheral oxygen, time-to-intubation and the number of intubation attempts. As a result, this study found no statistical significance in the hemodynamic parameters after 10 min of laryngoscopy. However, the time-to-intubation was significantly higher in the direct laryngoscopy group, and the frequency of success on the first intubation attempt in the video laryngoscopy group was significantly higher. The authors concluded that the video laryngoscopy technique is a better choice for conducting laryngoscopy with more success in intubation.

4

Which type and blade of video laryngoscope should be used?

Video laryngoscopes constitute a heterogeneous group of devices. They widely vary in terms of types of blades. Blades can be hyperangulated or follow a standard shape (i.e. Macintosh blade) and can be channelled or non-channelled. Channelled blades help direct the tube to the larynx, while non-channelled ones need to be used with a device to direct the tube, such as a stylet. As can be seen in Table 1 , our review showed that this variety was reproduced in the studies. Only one study compared a channelled blade (Blajic et al. [ ]). This might represent a decrease in the use of this type of blade. Regarding angulation of the blade, some studies investigated standard-shaped blades, while others studied hyperangulated blades. Such heterogenicity and the small number of patients studied in each blade shape prevent the authors from drawing any conclusions in terms of which blade is the best approach for obstetric airway management based on the literature.

Table 1

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