European Journal of Cardiovascular Medicine

Endotracheal intubation is essential for airway management during anesthesia. Traditional laryngoscopy can cause hemodynamic changes (hypertension, tachycardia) and risks like myocardial ischemia and laryngeal injury. Postoperative issues include sore throat and hoarseness. Medications (e.g., beta blockers) can mitigate these effects but may have side effects. Non-pharmacological methods, like video laryngoscopy and fiberoptic intubation, are less invasive and reduce hemodynamic changes.

HYPOTHESIS

Fiberoptic intubation significantly reduces hemodynamic fluctuations and postoperative complications compared to conventional laryngoscopy. It is hypothesized that patients undergoing fiberoptic intubation will experience less increase in heart rate and blood pressure during the procedure and fewer complications such as sore throat and soft tissue trauma.

Objective

This study compared the efficacy, safety, and clinical outcomes of fiberoptic vs. conventional laryngoscopic intubation in elective surgery patients. Key factors evaluated included hemodynamic responses (heart rate, blood pressure), intubation time, and post-procedural complications. Hemodynamic changes were monitored to assess sympathetic stimulation, while intubation duration was compared. The study also assessed post-procedural complications to evaluate safety and outcomes for each method.

Study Design

This study compared intubation conditions, hemodynamic responses, and post-procedural complications between conventional laryngoscopic and fiber-optic bronchoscope intubation. A total of 200 patients were randomly assigned to two groups of 100. The study was registered with the Clinical Trial Registry of India (CTRI/2022/03/041442). Group A used the conventional Macintosh laryngoscope (Romsons Scientific & Surgical Pvt. Ltd., Agra, Uttar Pradesh, India), while Group B used a fiberoptic bronchoscope (Karl Storz GmbH & Co. KG,Tuttlingen, Germany), which allows indirect airway visualization with less soft tissue manipulation.

Setting

The study was conducted from January 2016 to December 2017 at Indraprastha Apollo Hospitals, New Delhi, with ethical approval and informed consent from all patients. Participants were ASA grade I or II, aged 18–45, and scheduled for elective surgeries requiring tracheal intubation. Exclusion criteria included difficult airway indicators (Mallampati score ≥ 3), obesity (BMI > 30), pediatric patients, pregnant women, and those with contraindications like maxillofacial trauma or cervical spine instability. Randomization was done using a concealed chit-box method, with group allocation revealed just before intubation to maintain blinding.

Procedure

All patients underwent a preoperative airway assessment using the Mallampati score, thyromental distance, neck circumference, and other parameters predicting difficult intubation. Standard fasting protocols were followed, and an 18G or 20G IV cannula was inserted. Baseline vital signs (HR, SBP, DBP, SpO2) were recorded. Patients were pre-medicated with fentanyl (2 mcg/kg) and induced with propofol (2 mg/kg). Neuromuscular blockade was achieved with atracurium (0.5 mg/kg) after confirming mask ventilation. All patients were ventilated with 100% oxygen and sevoflurane for three minutes before intubation. Depending on group allocation, intubation was performed using either a conventional laryngoscope (Group A) or a fiber-optic bronchoscope (Group B).

In Group A, intubation was done with a conventional Macintosh laryngoscope, directly visualizing the vocal cords. After passing the endotracheal tube through the cords, placement was confirmed with capnography. In Group B, fiberoptic intubation was performed using an Ovassapian airway, guiding the bronchoscope through the glottis. The endotracheal tube was advanced over the bronchoscope, and correct positioning was confirmed via capnography.

Parameters Assessed

Intubation time was defined as the duration from mask ventilation cessation to effective endotracheal tube ventilation, confirmed by capnography, providing an objective measure of technique efficiency.

Hemodynamic parameters (heart rate and blood pressure) were recorded at baseline, three minutes after induction, and at 1-minute intervals for five minutes post-intubation to analyze responses for each technique.

Post-procedural complications, including sore throat, soft tissue or dental injuries, bleeding, stridor, and hoarseness, were monitored in the post-anesthesia care unit and during a 24-hour follow-up to assess patient safety and comfort.

Statistical Analysis

Data were analyzed using SPSS version 23.0. Continuous variables were presented as mean ± standard deviation. Comparisons of continuous variables used Student’s t-test, while categorical data were analyzed with Chi-squared or Fisher’s exact test, as appropriate. Statistical significance was set at p < 0.05.

Demographics

The study included 200 patients, equally divided into two groups: Group A (100 patients with conventional laryngoscopic intubation) and Group B (100 patients with fiberoptic intubation). Demographic variables (age, gender, weight, height, BMI) were comparable between groups (p > 0.05). The mean age in Group A was 31.83 ± 7.8 years and in Group B was 31.23 ± 7.6 years. Gender distribution was similar: Group A had 53 females and 47 males, while Group B had 47 females and 53 males. Mean BMI was also similar (Group A: 23.26 ± 1.8, Group B: 23.22 ± 2.2, p = 0.08), indicating well-balanced groups. However, when comparing the intubation times, a notable difference emerged. The average time required for intubation was significantly longer in Group B (fiberoptic intubation) compared to Group A (conventional laryngoscopic intubation).

The difference in intubation time between the two groups was statistically significant (p < 0.01), with fiberoptic intubation taking about 6 seconds longer than conventional laryngoscopy [Table 1].

Table 1: Baseline Demographic and Clinical Characteristics of Study Groups

Hemodynamic Changes

Hemodynamic parameters (heart rate, systolic blood pressure, and diastolic blood pressure) were compared between conventional laryngoscopy (Group A) and fiberoptic intubation (Group B) at various time points before and after intubation [Table 2].

Table 2: Mean (SD) of Heart Rate, SBP, DBP and SPO2 before induction, after induction and at 5 subsequent minutes after intubation in both the groups

Heart Rate (HR):

Baseline HR was similar between the groups (Group A: 74.93 ± 11.8 bpm, Group B: 75.39 ± 8.9 bpm, p > 0.05). However, one minute post-intubation, HR rose significantly in Group A (95.74 ± 9.4 bpm) compared to Group B (80.99 ± 8.8 bpm, p < 0.05). This trend continued at three minutes (Group A: 92.19 ± 9.1 bpm, Group B: 80.33 ± 8.7 bpm, p < 0.05), indicating less sympathetic stimulation with fiberoptic intubation.

Systolic Blood Pressure (SBP):

Baseline SBP was similar (Group A: 125.46 ± 6.9 mmHg, Group B: 125.7 ± 6.6 mmHg, p > 0.05). One minute post-intubation, SBP increased more in Group A (135.52 ± 6.9 mmHg) than in Group B (114.57 ± 7.0 mmHg, p < 0.05). Five minutes post-intubation, SBP remained higher in Group A (123.69 ± 6.8 mmHg) compared to Group B (108.7 ± 18.2 mmHg, p < 0.05), suggesting more stable blood pressure with fiberoptic intubation.

Diastolic Blood Pressure (DBP):

Baseline DBP was comparable (Group A: 84.86 ± 6.3 mmHg, Group B: 85.24 ± 5.9 mmHg, p > 0.05). One minute post-intubation, DBP rose more in Group A (94.85 ± 6.3 mmHg) than in Group B (80.46 ± 5.7 mmHg, p < 0.05). At three minutes, DBP was still higher in Group A (88.06 ± 6.2 mmHg) compared to Group B (77.96 ± 5.7 mmHg, p < 0.05), further confirming less hemodynamic disturbance with fiberoptic intubation. Overall, these findings show that fiberoptic intubation results in fewer hemodynamic fluctuations than conventional laryngoscopy.

Post-procedural Complications

We found that hemodynamic responses, including changes in heart rate, systolic blood pressure, and diastolic blood pressure, were significantly lower in Group B (fiberoptic intubation) compared to Group A (conventional laryngoscopic intubation). This indicates that fiberoptic intubation may be associated with reduced sympathetic stimulation and greater hemodynamic stability during the intubation process.

Regarding oxygen saturation, the incidence of desaturation was the same in both groups, with 2 patients (2%) experiencing this complication. There was no statistically significant difference between the groups (p = 1.000), as shown in Table 3. However, sore throat was more common in Group A, where 11 patients (11%) reported this complication, compared to just 3 patients (3%) in Group B, reflecting a statistically significant difference (p = 0.024). After 24 hours, 3 patients (3%) in Group A still reported a sore throat, while no cases were observed in Group B, although this difference did not reach statistical significance (p = 0.080). A significant difference was observed in the occurrence of dental injury or soft tissue trauma, with 11 patients (11%) in Group A experiencing these complications, while no such cases were reported in Group B (p < 0.001). Other complications, including stridor, cough, and dysphonia, were noted in 1 patient (1%) in Group A and none in Group B, but this difference was not statistically significant (p = 0.317). These findings suggest that fiberoptic intubation may reduce the risk of post-procedural complications compared to conventional laryngoscopic intubation, thereby enhancing patient comfort and safety [Table 3].

Table 3: Comparison of Post-procedural Complications

Hemodynamic Changes

The study's findings align with previous research showing that conventional laryngoscopy causes pronounced hemodynamic responses, such as increased heart rate and blood pressure from airway stimulation. For instance, Aslam et al. found that conventional laryngoscopy produced more intense hemodynamic changes compared to fiber-optic bronchoscopy [1]. Similarly, Ali et al. demonstrated that laryngoscopy resulted in greater increases in mean arterial pressure and heart rate than fiber-optic techniques [2].

Intubation Time

The longer intubation time for fiberoptic intubation is supported by Ali et al., who noted it takes nearly twice as long as conventional laryngoscopy [2]. Adachi et al. also highlighted that fiberoptic techniques, despite being advanced, require more time due to the precision needed [3]. Shrestha et al. recommend fiber-optic intubation primarily for elective surgeries due to the importance of speed in emergencies [4].

Post-procedural Complications

Our study found fewer complications with fiberoptic intubation, including less sore throat and tissue trauma, consistent with Shrestha et al., who reported lower rates of postoperative sore throat and hoarseness with fiberoptic techniques [4]. Brzanov et al. similarly found fewer airway complications in the Airtraq group compared to conventional methods, supporting fiberoptic intubation as less traumatic [5].

Routine Use of Fiberoptic Intubation

Fiberoptic intubation enhances safety in elective surgeries by minimizing soft tissue and dental trauma. Arar showed that a modified bite block aids patients with limited neck mobility, making it preferable for difficult airways [6].

Hemodynamic Stability

This technique triggers a smaller sympathetic response than traditional methods. Ali et al. found fewer increases in blood pressure and heart rate, improving safety for cardiac patients [2]. Badiger et al. demonstrated that high-flow nasal oxygen optimises oxygenation and reduces desaturation risks [7].

Training and Learning Curve

The longer learning curve limits its use. Structured, simulation-based training improves proficiency. Binstadt et al. noted that simulator training enhanced emergency residents' skills [8], while Erb et al. found hands-on training with anesthetized patients led to high success rates [9].

Limitations of the Study

This study has several limitations. First, it was conducted in a controlled, elective surgery setting, which may not reflect the challenges of emergency intubations, where longer times could jeopardize patient safety. Second, the exclusion of complex patients (e.g., those with difficult airways or obesity) limits the generalizability of the findings to higher-risk populations. Lastly, variability in operator skill may have influenced the results, as differences in experience could affect intubation times and complication rates, reducing the applicability across different proficiency levels.

Future Directions

To better understand and apply fiberoptic intubation, further research is needed in several areas. First, studies should explore its effectiveness in patients with difficult airways, obesity, or conditions like obstructive sleep apnea. Vaez et al. identified morbid obesity as a key factor complicating intubation, suggesting fiberoptic techniques may need adaptation for these patients [10]. Wu et al. recommended supraglottic jet oxygenation and ventilation (SJOV) to improve oxygenation during fiberoptic intubation in challenging cases [11].

Research on fiberoptic intubation in emergency settings is also vital. While it has been life-saving in specific scenarios, as noted by Varghese et al. in oncological emergencies, more studies are needed to assess its use in various urgent situations [12]. Trimmel et al. stressed optimizing the technique for speed to reduce intubation times in critical conditions [13].

Finally, improved training programs are necessary due to the steep learning curve of fiberoptic intubation. Guglielmi et al. advocated for structured dummy training to build skill and confidence [14], and Binstadt et al. showed that simulation-based training enhances performance, highlighting the importance of hands-on experience [8].

The study shows fiberoptic intubation (FOI) provides better hemodynamic stability than conventional laryngoscopy, with less heart rate and blood pressure fluctuation post-intubation. FOI also leads to fewer postoperative complications, such as soft tissue trauma and sore throats, due to the flexible bronchoscope. However, FOI takes longer and has a steeper learning curve, which can be a limitation in emergencies. Despite this, its safety benefits often outweigh the longer duration. These findings are particularly relevant for cardiovascular patients, as FOI reduces heart rate and blood pressure variability, aiding recovery. FOI should be considered in routine anesthesia, as its benefits extend beyond difficult airways. The additional time in elective surgeries is justified by improved safety, and better training may further reduce procedure times.

Disclosures

Human subjects: Consent was obtained or waived by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

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