Intubation difficulties: definition and significance

Intubation difficulties are not uncommon. According to clinical reviews, the incidence of unexpected intubation difficulties ranges from 0.1 % to 10.1 % of all anaesthetic procedures. It is worth noting that, according to published studies, around 93 % of these cases cannot be predicted in advance. Even in well-planned procedures, there therefore remains a residual risk — a factor that is relevant from both a medical and a financial perspective.

Cormack and Lehane classification: Severity grades I to IV

Anaesthetists use the Classification according to Cormack and Lehane during laryngoscopy, to assess how clearly the glottis is visible. Grades III and IV are clinically regarded as difficult laryngoscopies. Experience has shown that these cases require a systematic approach following a step-by-step algorithm and the early use of aids.

Classification according to Cormack and Lehane (1984): The higher the grade, the more difficult the intubation. Grades I and II are considered uncomplicated, whilst grades III and IV require specialised techniques and experienced anaesthetists.

Degree	Visibility of the glottis	Clinical implications
Grade I	The vocal fold is fully visible	Intubation is possible without any problems
Grade II	Posterior parts of the glottis are visible	Possible; BURP manoeuvre if necessary
Grade III	Only the epiglottis is visible; the glottis is not visible	Difficult; video laryngoscopy or a guide rod required
Grade IV	No laryngeal structures visible	Very difficult: fibre-optic or surgical airway management

Modification according to Samsoon and Young

The modification proposed by Samsoon and Young supplements the original Cormack-Lehane classification by introducing a subdivision of Grade II. Grade IIa refers to a situation in which the posterior commissure of the glottis is still visible. Grade IIb is present when only the arytenoid cartilage remains visible. This distinction has practical value: clinically, Grade IIb is close to Grade III. It therefore justifies the early use of aids. The BURP manoeuvre – applying manual pressure to the thyroid cartilage (Backward, Upward, Rightward Pressure) – improves visibility in Grade II and III cases. It is considered the first line of treatment before more complex alternative procedures are employed.

Causes and risk factors

Intubation difficulties arise from a combination of anatomical factors, physical characteristics and pre-existing conditions. The RODS mnemonic provides a concise summary of the four most common predictors:

• R — Restricted mouth opening: limited mouth opening (interincisal distance of less than 3 cm)
• O — Obstruction: blockage of the upper airways caused by a tumour, haematoma or abscess
• D — Disrupted or distorted oropharynx: anatomical abnormalities in the throat and mouth
• S — Stiff cervical spine or lungs: restricted mobility of the cervical spine, e.g. due to spondylarthrosis

Anatomical and patient-specific risk factors in detail

Obesity increases the incidence of intubation difficulties to around 11 %; in patients of normal weight, this figure is around 7 %. Increased soft tissue in the neck restricts the view of the glottis and makes laryngoscopy more difficult.

The Mallampati score is regarded as another established predictor. In the Mallampati test, the patient opens their mouth wide and sticks out their tongue. The anaesthetist assesses how much of the pharyngeal structure is visible. Scores III and IV — in cases where the palatine tonsils or the posterior pharyngeal wall cannot be visualised — are associated with an increased likelihood of difficult laryngoscopy. Further anatomical risk factors:

• A short, thick neck with reduced mobility
• Receding chin (retrogenia)
• Previous radiotherapy or surgery in the head and neck region
• Pregnancy (changes in mucosal blood flow and anatomy)
• Well-known conditions such as rheumatoid arthritis with atlantoaxial instability
• Patients aged over 55 with degenerative changes in the cervical spine

The 3-3-2 rule supplements the risk assessment using finger measurements: the mouth must be open by at least 3 fingers’ width, there must be a gap of at least 3 fingers’ width between the chin and the hyoid bone, and at least 2 fingers’ width between the hyoid bone and the thyroid cartilage. If these distances fall below the minimum values, laryngoscopy is likely to be difficult.

How is a difficult airway managed?

The management of intubation difficulties follows a step-by-step approach in accordance with the guidelines issued by the German Society for Anaesthesiology and Intensive Care Medicine (DGAI). The approach makes a fundamental distinction between anticipated and unexpected airway difficulties.

Anticipated difficult airway: planning before anaesthesia

If pre-operative findings suggest that intubation may be difficult, the anaesthetist plans airway management before induction of anaesthesia. The standard procedure is the Fibre-optic intubation (FOI) whilst the patient is awake. The patient remains conscious throughout and breathes spontaneously. The anaesthetist numbs the mucous membranes with a local anaesthetic and inserts the flexible fibre-optic endoscope through the nose or mouth into the trachea. Only once the tube is securely in place is general anaesthesia administered.

Alternatively, there is the Video laryngoscopy is used. A miniaturised camera on the blade of the laryngoscope displays the glottis on a monitor — without the need for a direct line of sight between the mouth and the larynx. Video laryngoscopes have largely replaced direct laryngoscopy in cases where difficult airways are anticipated. They offer a significantly better view and have a shorter learning curve than the FOI.

Unexpectedly difficult airway: a structured approach

Unexpectedly difficult intubations occur without warning. They put the clinical team under time pressure. The DGAI algorithm sets out the following step-by-step procedure:

1. Optimisation of storage Raise the head to a „sniffing position“; if necessary, place a support under the shoulders of obese patients.
2. Another attempt using an improved technique BURP manoeuvre, spatula change (e.g. to a straight Miller spatula), guide rod in the tube.
3. Video laryngoscopy After two unsuccessful attempts, switch immediately to a video laryngoscope.
4. Supraglottic airway device Insertion of a laryngeal mask or a laryngeal tube to maintain airway patency and provide oxygenation for the patient.
5. Waking the patient Termination of anaesthesia unless there is an emergency indication. Planning a new procedure with an enhanced setup.
6. Surgical airway management Last resort in a CICO situation — cricothyroidotomy or emergency tracheotomy.

Pre-operative assessment: How anaesthetists identify risks at an early stage

Pre-operative risk assessment is the most effective tool for preventing unanticipated intubation difficulties. Anaesthetists systematically record all relevant findings during the pre-operative consultation. The following charts show which factors are assessed:

If the assessment indicates an increased risk, the anaesthetist prepares an extended set of instruments: several laryngoscope blades of various shapes, a video laryngoscope, guide rods, a laryngeal mask and, if necessary, the fibre-optic set. This pre-operative preparation of the „difficult airway trolley“ is standard practice in anaesthesia departments.

Anyone who has experienced intubation difficulties during previous operations should Anaesthesia card be documented. The anaesthesia record is a standardised document that records the degree of difficulty, the Cormack-Lehane score and the equipment used. In accordance with the DGAI’s recommendation, this record is given to the patient so that they can present it at any future procedure.

Implications for cosmetic surgery patients: medical risks and financial consequences

Cosmetic surgery is predominantly carried out under general anaesthesia. This means that, in principle, every patient is exposed to the risk of intubation difficulties — regardless of whether the procedure is liposuction, a nose job or a breast lift. Many patients underestimate both aspects of this risk: the medical and the financial.

Possible medical consequences of intubation difficulties

If intubation difficulties arise, the time taken to establish secure ventilation is prolonged. During this phase, there is a risk of hypoxia, i.e. a lack of oxygen in the blood. Other possible complications arising from repeated intubation attempts include:

• Lesions to the mucous membranes in the throat, larynx or trachea
• Aspiration of stomach contents into the lungs (aspiration pneumonia)
• Laryngospasm — a reflex spasm of the glottis
• Bronchospasm with difficulty breathing
• Damage to teeth or injuries to the lips and oral mucosa
• In exceptional cases: prolonged intensive care follow-up and ventilation

The vast majority of cases result in no lasting damage, as experienced anaesthetists follow a clear protocol. However, even intubation difficulties that are well managed can trigger medically necessary follow-up treatment — and thus incur significant follow-on costs.

Financial implications: Who pays if complications arise following cosmetic surgery?

In the case of elective cosmetic surgery paid for privately, statutory health insurance funds will only cover the costs of medically necessary follow-up treatment under certain conditions. If intubation complications arise following cosmetic surgery, health insurance funds may sometimes demand reimbursement of the costs they have paid.

In practical terms, this means that anyone who is placed on a ventilator in an intensive care unit on an unplanned basis due to intubation complications, or who requires revision surgery, will face significant costs. Insurance covering consequential costs can bridge this financial gap. 4beauty offers insurance cover for medically necessary treatments resulting from the insured procedure — regardless of whether the complication was foreseeable or not.

You can find information on the specific treatments and procedures covered by insurance in the Overview of all covered treatments. Frequently asked questions about the scope of cover are answered in the 4beauty’s FAQ section.

Frequently asked questions about intubation difficulties