Intubation
Intubation is a critical medical procedure involving the insertion of a flexible tube through the mouth or nose into the trachea (windpipe) to secure and maintain an open airway, thereby facilitating oxygenation, ventilation, and protection against aspiration.[1][2] This technique, most commonly performed as endotracheal intubation, is essential in emergency and critical care settings to support patients who cannot breathe adequately on their own due to respiratory failure, airway obstruction, or unconsciousness.[3] While it can also apply to other hollow organs like the stomach for purposes such as removing contents or delivering nutrition, the term predominantly refers to airway management in clinical practice.[1] The primary indications for intubation include hypoxemic respiratory failure, where oxygen levels remain low (PaO₂ <60 mmHg) despite supplemental oxygen, as seen in conditions like pneumonia, pulmonary edema, or acute respiratory distress syndrome (ARDS).[4][5] It is also indicated for hypercapnic respiratory failure involving elevated carbon dioxide (PaCO₂ >45 mmHg) with acidosis (pH <7.35), common in chronic obstructive pulmonary disease (COPD) exacerbations or severe asthma.[4] Additional scenarios encompass airway protection in patients with low Glasgow Coma Scale scores (≤8), such as those with head injuries, intoxication, or inability to clear secretions, as well as upper airway obstructions from tumors, angioedema, or trauma.[3][4] Relative indications may involve neuromuscular weakness, as in Guillain-Barré syndrome, or procedural needs during surgery or imaging where hemodynamic stability is at risk.[4] The procedure typically begins with pre-oxygenation using high-flow oxygen for at least three minutes to achieve an end-tidal oxygen concentration of approximately 90% while delivering high inspired oxygen fraction (FiO₂), followed by patient positioning in the "sniffing" posture to optimize airway alignment.[3] Rapid sequence intubation (RSI) is often employed in emergencies, involving administration of induction agents and paralytics, after which a laryngoscope—either direct or video-assisted—is used to visualize the vocal cords and guide the endotracheal tube (typically sized 7.0-8.0 mm for adults) beyond them into the trachea.[2][3] Placement is confirmed via end-tidal CO₂ monitoring, auscultation of breath sounds, and chest X-ray, with the tube's cuff inflated to prevent leaks and aspiration.[3] The tube is then connected to a ventilator or oxygen source to support breathing, and medications may be delivered directly through it.[1] Despite its life-saving potential, intubation carries risks including hypoxemia during the process, trauma to the teeth, lips, larynx, or trachea, and rare but serious complications like esophageal intubation, aspiration pneumonia, or tracheal perforation leading to lung collapse.[2][3] Cardiovascular effects, such as bradycardia from vagal stimulation, and infections are also possible, underscoring the need for skilled practitioners, sterile technique, and immediate post-procedure monitoring in a hospital setting.[3][2] Overall, successful intubation outcomes depend on the underlying condition, with ongoing advancements in video laryngoscopy improving success rates in difficult airways.[3]Overview and Fundamentals
Definition and Etymology
Intubation is a medical procedure involving the insertion of a flexible tube, typically an endotracheal tube, into the trachea through the mouth or nose to secure and maintain an open airway.[6] This intervention facilitates mechanical ventilation, delivers oxygen, and protects the lower airways from aspiration of gastric contents or secretions.[2] In clinical practice, it is performed under direct visualization or with assistive devices to ensure proper placement within the trachea, bypassing potential obstructions in the upper airway.[3] The term "intubation" derives from the Latin roots "in-" meaning "into" and "tubus" meaning "tube," reflecting the act of introducing a tubular device into a body structure.[7] Coined in the late 19th century, it first appeared in medical literature around 1885 in reference to treatments for conditions like croup, where tubes were inserted into the larynx to relieve airway obstruction.[8] While historically the term encompassed broader applications such as tube insertion into various organs—for instance, in early esophageal or laryngeal procedures—modern usage predominantly restricts "intubation" to airway management techniques involving the trachea.[3] This evolution underscores its specialization in respiratory care, distinguishing it from other tubular interventions like nasogastric or urinary catheterization.[9] As a cornerstone of airway management, intubation serves as a critical, often life-saving intervention in cases of respiratory failure, enabling positive pressure ventilation and hemodynamic stabilization when spontaneous breathing is inadequate.[10]Clinical Importance and Applications
Intubation plays a pivotal role in modern medicine by securing airway patency, which is essential for maintaining oxygenation and ventilation in patients unable to breathe adequately on their own.[3] This procedure enables the delivery of positive pressure ventilation, allowing mechanical support to inflate the lungs effectively during respiratory compromise.[11] Additionally, it facilitates suctioning of secretions to clear the airway and prevents aspiration of gastric contents or oral secretions in unconscious or obtunded patients, thereby reducing the risk of pneumonia and other complications.[12] These applications are critical in scenarios where spontaneous breathing is impaired, ensuring hemodynamic stability and organ perfusion.[9] The clinical significance of intubation extends across multiple specialties, including emergency medicine, where it is often performed to stabilize patients in acute distress; anesthesiology, for controlled airway management during surgical procedures; intensive care, to support prolonged ventilation in critically ill individuals; and trauma care, to address airway threats from injury.[13][14] In emergency settings, timely intubation can be lifesaving by optimizing oxygenation and preventing further deterioration.[15] Statistical data underscore its impact: in skilled hands, first-pass success rates for endotracheal intubation in respiratory arrest or cardiac arrest scenarios reach approximately 80-85%, with overall success exceeding 95% within two attempts, as of 2025.[16][17] Ethical considerations in intubation involve weighing its life-sustaining benefits against potential risks, particularly in vulnerable populations such as pediatric and geriatric patients. In pediatrics, the procedure must balance airway protection with the heightened risk of barotrauma from mechanical ventilation, which can lead to pneumothorax or other air leak syndromes due to smaller airway compliance.[18] Geriatric patients face amplified risks of complications like barotrauma or aspiration despite intubation, necessitating careful assessment of frailty and comorbidities to avoid undue harm.[19] Informed consent and discussions about do-not-intubate orders are crucial, ensuring decisions align with patient autonomy and overall prognosis while minimizing iatrogenic injury.[20]Historical Development
Early Innovations
The earliest documented references to airway management techniques resembling intubation appear in ancient medical texts. Around 400 BCE, Hippocratic writings described the use of oral tubes to alleviate airway obstruction, advocating for the insertion of a cannula through the mouth to facilitate breathing in cases of respiratory distress.[21] These methods, though rudimentary, represented an initial attempt to bypass upper airway blockages without surgical incision, drawing on observations of natural recovery processes in obstructed patients.[22] Significant progress occurred in the 19th century amid rising diphtheria epidemics, which necessitated innovative interventions for laryngeal obstruction. In 1878, Scottish surgeon William Macewen performed the first successful endotracheal intubation as an alternative to tracheotomy on a patient with laryngeal scalding, using a metal tube inserted orally under chloroform anesthesia to secure the airway during recovery.[22] This marked a milestone in elective intubation, demonstrating its potential as a less invasive alternative to tracheotomy for maintaining ventilation.[23] Shortly thereafter, in 1880, American physician Joseph O'Dwyer introduced a system of endotracheal tubes specifically for diphtheria treatment, involving the blind insertion of graduated metal tubes through the mouth to relieve glottic swelling in children.[24] Key developments in tube design further advanced these techniques. O'Dwyer's innovations included rigid metal laryngeal tubes of varying sizes, secured with silk threads and left in place for days to support breathing until the obstruction resolved; by 1895, these had become widely adopted for pediatric cases, reducing mortality from diphtheria-related asphyxia.[22] Early rigid metal tubes, such as those refined in the late 19th century, were typically straight and unyielding, allowing for temporary airway patency but requiring manual insertion without visualization aids.[25] Despite these breakthroughs, early intubation faced substantial challenges that curtailed widespread adoption. High infection rates plagued procedures, as antisepsis practices were not yet standardized, leading to frequent complications like mediastinitis in diphtheria patients.[22] Additionally, the lack of reliable anesthesia prior to the mid-19th century made insertions excruciating, particularly for conscious children, often resulting in procedural resistance and incomplete airway control.[26] These limitations confined intubation primarily to emergency settings for life-threatening obstructions, with success rates varying widely based on operator skill and patient condition.[22]Advancements in the 20th and 21st Centuries
In the early 20th century, significant progress in intubation materials and techniques emerged, building on rudimentary 19th-century methods. In the 1920s, British anesthetist Sir Ivan Whiteside Magill introduced flexible rubber endotracheal tubes, which allowed for safer and more adaptable insertion, particularly for nasal intubation, and developed specialized forceps to facilitate their placement.[27] This innovation marked a shift toward more precise and less traumatic airway management during surgery.[28] A pivotal advancement came in 1928 when American anesthesiologist Arthur E. Guedel developed the cuffed endotracheal tube, featuring an inflatable cuff that sealed the trachea to prevent aspiration of gastric contents and ensure positive pressure ventilation. This design greatly reduced complications in prolonged procedures and became a standard in anesthesia practice.[27] Following World War II, the 1940s and 1950s saw the widespread adoption of direct laryngoscopy, enhanced by specialized blades that improved visualization of the glottis. Robert A. Miller's straight laryngoscope blade, introduced in 1941, provided better elevation of the epiglottis for pediatric and certain adult intubations.[27] Concurrently, Robert R. Macintosh's curved blade, patented in 1943, allowed indirect lifting of the tongue and epiglottis, simplifying the procedure and increasing success rates in routine cases.[29] These tools standardized intubation training and application across medical settings.[28] Entering the 21st century, video laryngoscopy revolutionized difficult airway management by incorporating camera technology for enhanced glottic views. The GlideScope, the first commercially available video laryngoscope, was introduced in 2001 by Canadian inventor John Pacey, enabling real-time monitoring on a screen and improving first-attempt success rates in challenging scenarios by up to 20% compared to direct laryngoscopy.[30] This device, with its angled blade and digital imaging, reduced the need for excessive force and minimized cervical spine manipulation.[31] Recent years have integrated artificial intelligence (AI) into intubation devices, providing real-time feedback and predictive analytics to boost procedural efficiency. As of 2025, AI-assisted systems, such as those using deep learning for laryngoscope depth detection and robotic guidance, have demonstrated first-attempt success rates of 87-96% in emergency settings, representing improvements of 20-40% over traditional methods with minimal user training.[32][33] These tools analyze video feeds to alert on misalignment or predict difficult airways, enhancing safety in high-stakes environments like intensive care units.[34] The COVID-19 pandemic from 2020 to 2023 accelerated protocol refinements to address aerosol generation risks during intubation. Enhanced rapid sequence intubation (RSI) techniques, including preoxygenation without bag-mask ventilation and prioritized use of video laryngoscopes, minimized viral spread by reducing procedure duration and exposure time for healthcare workers.[35] Checklists and multidisciplinary algorithms further standardized these practices, lowering complication rates in infected patients while maintaining high success in emergency airway control.[36]Types of Intubation
Orotracheal Intubation
Orotracheal intubation is defined as the insertion of an endotracheal tube through the oral cavity into the trachea to secure the airway and facilitate mechanical ventilation, typically performed under direct visualization using a laryngoscope.[3] This method involves advancing the tube past the oral structures and through the vocal cords to position its distal end above the carina, ensuring proper placement within the trachea.[3] One key advantage of orotracheal intubation is its rapidity of placement, making it the preferred approach in emergency situations where quick airway control is essential.[37] Additionally, the oral route permits the use of larger diameter tubes compared to nasotracheal intubation, which enhances ventilation efficiency by reducing airway resistance and improving suctioning capabilities.[38] In brief, while nasotracheal intubation may be suitable for certain awake procedures, orotracheal intubation excels in scenarios requiring faster intervention.[37] Endotracheal tubes used in orotracheal intubation are typically sized 7.0 to 8.5 mm in internal diameter for adults, with 7.0 mm recommended for females and 8.0 mm for males to optimize airflow while minimizing trauma.[39] These tubes are commonly constructed from polyvinyl chloride (PVC) for its flexibility and durability, though silicone variants are also employed for their biocompatibility in prolonged use.[39][40] A high-volume, low-pressure inflatable cuff at the distal end is inflated with 10-20 ml of air to create a seal against the tracheal wall, preventing aspiration and enabling positive pressure ventilation while maintaining cuff pressure below 20 cm H2O to avoid mucosal ischemia.[39] Anatomically, orotracheal intubation requires careful navigation through the oral cavity, where the laryngoscope blade is inserted along the right side of the mouth to displace the tongue laterally and protect the teeth from damage.[3] The tube must then pass over the tongue and base of the epiglottis, with the blade used to elevate the epiglottis—either by placing a curved blade in the vallecula or a straight blade directly under the epiglottis—to expose and traverse the vocal cords without trauma.[3] This pathway demands alignment of the oral, pharyngeal, and laryngeal axes to ensure smooth advancement into the trachea.[3]Nasotracheal Intubation
Nasotracheal intubation is a technique that involves passing an endotracheal tube through one nostril, along the floor of the nasal cavity into the nasopharynx, and then advancing it through the glottis into the trachea to secure the airway.[41] This method is particularly suited for scenarios requiring prolonged mechanical ventilation, as it facilitates better oral access for feeding, oral hygiene, or surgical interventions compared to orotracheal intubation.[42] One key advantage of nasotracheal intubation is its superior tolerance in awake or lightly sedated patients, owing to the less invasive sensation relative to oral routes, making it preferable for certain elective procedures.[41] It is especially beneficial in ear, nose, and throat (ENT) surgeries, such as maxillofacial or dental operations, where unobstructed intraoral access is essential for the surgical field.[42] Additionally, when properly secured, nasotracheal tubes exhibit reduced movement and lower risk of dislodgement or trauma to oral structures like the lips and tongue.[43] However, this route carries unique risks, including epistaxis, which arises from trauma to the vascular nasal mucosa and occurs in approximately 18-77% of cases, though most episodes are mild and self-limiting.[44] Prolonged nasotracheal intubation also heightens the potential for sinusitis due to obstruction of paranasal sinus drainage, potentially leading to bacterial overgrowth and inflammation.[45] To accommodate the narrower nasal passage, nasotracheal tubes are adapted with smaller internal diameters, typically 6.0-6.5 mm for adult females and 6.5-7.0 mm for adult males, ensuring passage without excessive force.[46] These tubes often feature pre-curved tips, such as the Magill configuration, to facilitate navigation around anatomical bends in the nasopharynx, and are constructed from materials like polyvinyl chloride (PVC) or silicone for flexibility and reduced trauma.[42]Specialized Techniques (e.g., Fiberoptic and Retrograde)
Fiberoptic bronchoscopy is a specialized intubation technique that employs a flexible endoscope equipped with a camera and light source to visualize and navigate the airway, allowing for precise placement of the endotracheal tube, particularly in awake patients or scenarios requiring blind intubation. This method is especially valuable for managing difficult airways where direct visualization is challenging, such as in cases of limited mouth opening or cervical spine instability. In skilled practitioners, fiberoptic intubation achieves success rates ranging from 88% to 100%.[47] Retrograde intubation represents another advanced approach, involving the insertion of a guidewire through a puncture in the cricothyroid membrane and advancing it retrograde into the oropharynx or hypopharynx, followed by antegrade railroading of the endotracheal tube over the wire. This wire-guided method is indicated for anticipated difficult airways, including those with anatomical distortions that preclude standard oral or nasal routes. It serves as a reliable alternative when fiberoptic equipment is unavailable, though it is now infrequently used due to the prevalence of less invasive options.[48] Additional variants include lightwand intubation, which utilizes a lighted stylet to transilluminate the neck and guide tube placement via external light confirmation of tracheal entry, and bougie-assisted intubation, where a flexible, angled introducer (such as a gum elastic bougie) is first advanced through the vocal cords under partial visualization before railroading the tube. These techniques enhance success in partially obscured views and are often employed adjunctively in complex cases.[49][50] As of 2025, emerging robotic-assisted systems have introduced greater precision to these specialized methods, integrating automated guidance and haptic feedback to improve intubation success rates and operational efficiency in difficult airway scenarios. Such innovations are particularly beneficial for anatomical distortions caused by trauma or tumors, where traditional maneuvers may fail due to structural alterations.[51][52]Indications
Emergency Airway Management
Emergency intubation is a critical intervention in life-threatening scenarios where immediate airway securing is essential to prevent hypoxia and support vital functions. Common indications include cardiopulmonary arrest, in which endotracheal intubation facilitates effective ventilation during resuscitation efforts to improve oxygenation and circulation.[53] In severe trauma, intubation is urgently required for patients experiencing hypoxia, hypoventilation, or inability to protect the airway due to altered consciousness or injury, as these compromise respiratory stability and increase mortality risk.[14] Anaphylaxis often necessitates emergency intubation when severe laryngeal edema or angioedema causes upper airway obstruction, potentially leading to rapid respiratory failure if not addressed promptly.[54] Similarly, an obstructed airway from foreign body aspiration demands immediate intubation if basic removal maneuvers fail, to restore patency and prevent asphyxiation.[3] Clinical decision-making in these emergencies follows established algorithms, such as the American Heart Association's Advanced Cardiac Life Support (ACLS) guidelines, which recommend considering advanced airway placement like intubation during cardiac arrest after initial bag-mask ventilation, prioritizing minimal interruptions to chest compressions.[55] The 2020 ACLS updates emphasize waveform capnography for verifying tube placement and monitoring end-tidal CO2 (ETCO2) levels, with values below 10 mm Hg indicating poor perfusion and above 20 mm Hg correlating with higher rates of return of spontaneous circulation.[53] The 2025 AHA guidelines reinforce this focus on capnography as a key tool for assessing CPR quality and airway patency in real-time during resuscitation.[56] In "can't intubate, can't oxygenate" crises, the goal is rapid airway establishment within 2-3 minutes to avert irreversible hypoxic damage, often escalating to supraglottic devices or surgical access if intubation fails.[50] Special considerations apply to vulnerable populations to optimize outcomes. In pediatrics, emergency intubation requires smaller endotracheal tubes (e.g., uncuffed for children under 8 years) due to narrower airways and higher resistance, with anatomic differences like a larger tongue and cephalad larynx increasing difficulty and necessitating adjusted techniques.[57] For obstetric patients, rapid sequence intubation is prioritized to mitigate aspiration risk from delayed gastric emptying and relaxed lower esophageal sphincter, employing cricoid pressure and fast-acting agents to secure the airway swiftly in peripartum emergencies.[58] Unlike elective procedures in controlled settings, these acute situations demand immediate, high-stakes actions without extensive premedication.[59]Elective Procedures and Anesthesia
In elective procedures, intubation is commonly employed during general anesthesia for surgeries requiring airway protection and controlled ventilation, such as abdominal operations, where the risk of aspiration or respiratory compromise is heightened under general anesthesia.[3] This approach is also utilized in intensive care units (ICUs) for patients needing sedation and mechanical ventilation over extended periods, often due to conditions like severe pneumonia or post-operative recovery, allowing for stable oxygenation without the urgency of life-threatening scenarios. Unlike emergency airway management, elective intubation occurs in a controlled setting with prior patient optimization, enabling meticulous planning to enhance safety and outcomes. Standard protocols for elective intubation emphasize rapid sequence induction (RSI), a technique involving the simultaneous administration of an induction agent like etomidate, which provides rapid onset of unconsciousness with minimal hemodynamic effects, and a neuromuscular blocker such as succinylcholine to facilitate quick paralysis and tube insertion. Preoxygenation with 100% oxygen via a tight-fitting mask for at least three minutes is a critical step, extending the safe apnea period to approximately 8-10 minutes by denitrogenating the lungs and creating an oxygen reservoir, thereby reducing hypoxemia risk during the procedure. These premeditated strategies are tailored based on patient comorbidities, such as cardiovascular stability, to minimize physiological perturbations. The benefits of elective intubation in a controlled environment include significantly lower complication rates compared to emergent situations, with studies reporting first-attempt success rates exceeding 90% when performed by experienced anesthesiologists. Recent trends as of 2025 highlight the integration of opioid-sparing anesthesia techniques, incorporating multimodal analgesia with agents like dexmedetomidine or regional blocks, which reduce postoperative nausea, respiratory depression, and chronic pain risks while facilitating smoother extubation. Considerations for intubation duration distinguish short-term use, typically under 24 hours for most elective surgeries, from prolonged applications in the ICU, where weaning protocols involve gradual sedation reduction, spontaneous breathing trials, and multidisciplinary assessment to prevent ventilator-associated complications like pneumonia. For short-term cases, emphasis is placed on rapid recovery to expedite patient discharge, whereas prolonged intubation requires vigilant monitoring of cuff pressures and enteral nutrition to maintain airway integrity.Preparation and Equipment
Patient Evaluation and Premedication
Patient evaluation prior to intubation involves a systematic assessment to identify potential airway difficulties and optimize procedural safety. Key tools include the Mallampati score, which classifies airway visibility based on the oropharynx view with the patient seated and mouth open (Class I: full visibility of soft palate, fauces, uvula, and pillars; Class IV: only hard palate visible), aiding in predicting intubation challenges.[60] Thyromental distance, measured from the thyroid notch to the mentum, should ideally exceed 6 cm; distances less than 6.5 cm suggest increased risk of difficult laryngoscopy.[61] Neck mobility assessment, often via the 3-3-2 rule (three finger breadths from mentum to hyoid, three from hyoid to thyroid notch, two from thyroid to cricoid), evaluates extension and flexion to anticipate obstacles during alignment of airway axes.[62] These evaluations help predict difficult airways, which occur in approximately 6% of adult elective cases, though rates vary by setting and definition.[63] Premedication aims to reduce patient anxiety, suppress airway reflexes, and facilitate intubation while minimizing physiological stress. Sedatives such as propofol are commonly administered at 1.5-2.5 mg/kg intravenously for induction, providing rapid onset hypnosis but requiring caution due to potential hypotension.[64] Paralytics like rocuronium, dosed at 1-1.2 mg/kg, induce neuromuscular blockade for optimal glottic visualization, with effects lasting 30-60 minutes.[65] Analgesics, including fentanyl at 1-2 mcg/kg, attenuate sympathetic responses and pain during the procedure. In pediatric patients, atropine (0.02 mg/kg) is often used to reduce oral secretions and prevent vagally mediated bradycardia associated with intubation.[66] Airway management follows established algorithms to guide preparation and contingency planning. The 2022 American Society of Anesthesiologists (ASA) Practice Guidelines for Management of the Difficult Airway recommend comprehensive preprocedural assessment, including history review and physical examination, followed by formulation of primary and alternative strategies.[67] Recent 2025 updates from the Difficult Airway Society (DAS) and All India Difficult Airway Association (AIDAA) emphasize circular algorithms with interchangeability between devices for enhanced oxygenation strategies.[68] [69] These guidelines emphasize backup plans, such as supraglottic airway devices or surgical intervention like cricothyrotomy, for anticipated failures to ensure oxygenation.[70] Intubation is contraindicated in cases of complete upper airway obstruction where bag-mask ventilation or alternative oxygenation is impossible, as attempts may worsen the blockage or cause trauma.[10]Essential Tools and Devices
Intubation requires a standardized set of equipment to ensure safe and effective airway management, with core items centered on visualization, tube insertion, and secure placement. The primary tool is the laryngoscope, typically featuring a handle with a light source and an interchangeable blade, such as the Macintosh curved blade in sizes 3 or 4 for adult patients, which facilitates visualization of the glottis during direct laryngoscopy.[3] Endotracheal tubes (ETTs), sterile single-lumen polyvinyl chloride tubes with an inflatable high-volume, low-pressure cuff, are essential for securing the airway, often inserted with a malleable stylet to guide placement and a 10-mL syringe for cuff inflation to prevent air leaks.[39] These components form the foundation of routine intubation kits, as outlined in emergency and anesthesia guidelines.[10] Adjunct devices enhance procedural reliability, particularly in challenging scenarios. A bougie, or tracheal tube introducer, serves as a flexible guide to navigate difficult airways when direct visualization is limited.[3] Oral airways maintain pharyngeal patency and prevent tongue obstruction, while suction devices, including Yankauer catheters connected to wall or portable suction, clear secretions or blood to optimize the view.[71] In response to heightened infection control needs following the COVID-19 pandemic, disposable video laryngoscopes—such as single-use blade systems with integrated cameras—are increasingly adopted and recommended to reduce cross-contamination risks compared to reusable models without compromising glottic exposure.[72][73] Equipment selection accounts for patient demographics, with ETT internal diameters typically ranging from 7.0 to 7.5 mm for adult females and 8.0 to 8.5 mm for adult males to minimize resistance while avoiding trauma, and smaller sizes (e.g., 3.0-6.0 mm) for pediatrics based on age and weight formulas.[39] Sterilization protocols emphasize single-use disposables for blades, stylets, and certain laryngoscope components to prevent microbial transmission, aligning with updated post-COVID standards from health authorities that prioritize high-level disinfection or discard for semi-critical devices.[74][75] Ventilation support equipment, such as the bag-valve-mask (BVM) system, is integral for preoxygenation prior to intubation, delivering high-flow oxygen via a self-inflating reservoir bag and non-rebreather mask to denitrogenate the lungs and extend safe apnea time.[10] This setup, often including an oxygen source and PEEP valve, ensures hemodynamic stability during the procedure.[76]Procedure Techniques
Direct Laryngoscopy Method
Direct laryngoscopy remains a conventional technique for endotracheal intubation, involving the use of a laryngoscope to directly visualize the glottis and guide the endotracheal tube into the trachea. However, the Difficult Airway Society 2025 guidelines recommend video laryngoscopy as the first-line approach due to improved efficacy and safety.[77] This method relies on aligning the oral, pharyngeal, and tracheal axes to facilitate visualization and tube placement and continues to be used in various elective and emergency settings.[3] The procedure typically begins with rapid sequence induction (RSI) to optimize conditions for intubation. Preoxygenation with 100% oxygen for 3-5 minutes is followed by administration of an induction agent, such as propofol or etomidate, to achieve unconsciousness, and a neuromuscular blocking agent, like succinylcholine or rocuronium, to induce paralysis and relax the airway muscles. Cricoid pressure, known as the Sellick maneuver, may be applied selectively to occlude the esophagus and reduce aspiration risk, though its routine use is debated in current guidelines due to potential interference with visualization and ventilation; the 2025 American Heart Association guidelines recommend against it during cardiac arrest but acknowledge limited evidence for benefit in non-arrest scenarios.[3][78][79] The step-by-step technique emphasizes precise patient positioning and instrument manipulation:- Positioning: Place the patient in the sniffing position, with the neck flexed and head extended to align the external auditory meatus with the sternal notch, elevating the head 3-7 cm using a pillow if needed; this optimizes the line of sight to the glottis.[80][3]
- Mouth opening and blade insertion: Use the right hand in a scissor-like motion to open the mouth widely, then insert the laryngoscope blade along the right side of the mouth, sweeping the tongue to the left to avoid teeth damage.[80]
- Vocal cord visualization: Advance a curved Macintosh blade into the vallecula to lift the epiglottis indirectly, or a straight Miller blade directly over the epiglottis; apply steady upward pressure at a 45-degree angle along the handle to expose the vocal cords without rocking the blade.[3][80]
- Tube advancement: With the glottis visualized, insert a lubricated endotracheal tube (typically 7.5-8.0 mm internal diameter for adult males, 7.0-7.5 mm for females) to the right of the blade, passing it through the vocal cords; advance the tube to a depth of 21-23 cm at the lips for adults, inflate the cuff with 5-10 mL of air, and remove the stylet before connecting to a ventilator or bag.[3][80]