Prediction of difficult tracheal intubation in ICU patients using MACOCHA score

Endotracheal intubation is a commonly performed procedure in the intensive care unit (ICU) for patients requiring ventilatory support. Non-elective intubation of critically ill patients in ICU is associated with a high rate of peri-procedural morbidity and mortality (1). A critical situation may be caused by lack of operator skills or patient factors such as shock, acidosis, hypoxemia due to acute respiratory failure and loss of consciousness causing a high risk for aspiration which requires rapid establishment of secured airways (2).

A large number of tests and scores such as LEMON, Wilson score, and mandibular protrusion test have been used for assessment of airway for patient requiring general anesthesia with endotracheal intubation. However only test available for assessing airway in ICU patients requiring mask ventilation and endotracheal intubation is MACOCHA score developed by De Jong (3) is one test used for ICU patients.

Seven clinical items available in the ICU were identified as independent risk factors for difficult intubation and constituted the MACOCHA score established by de Jong. The ‘MACOCHA’ score calculation includes patient characteristics: Mallampati score III or IV, Apnea syndrome (obstructive), Cervical spine limitation, Opening mouth < 3cm, Coma, Hypoxia, Anesthesiologist nontrained.Higher score levels particularly at the maximum levels (12 points) were associated with extremely difficult intubation and complications (3).

In ICU patients Mallampati score alone is less effective than MACOCHA score to predict difficult intubation. Two factors specific to ICU patients were recognized in this study and are included in the score: severe hypoxemia before intubation and coma (Glasgow score 8 as a reason for intubation). Severe hypoxemia as a risk factor can be explained by a shortness of time to be adequately prepared for the intubation and perhaps by increased stress for physicians performing the procedure. Likewise, patients intubated for coma often present increased oropharyngeal secretions, limiting view of the glottis.

The MACOCHA score is highly reliable tool to identify those patients in whom the failure rate of non-anaesthesiologist was 100%. It is a convincing finding that a definitive failure seems to be predictable. The MACOCHA score is a simple tool, which can be performed within a very short time period and seems to be superior to Mallampati classification(2). Early identification of risk factors for difficult intubation could allow for anticipation and preparation of adequate material, use of an alternative intubation strategy, and call on additional assistance before intubation and thus reduce morbidity.

Difficult intubation was defined as three or more laryngoscopic attempts to place the endotracheal tube into the trachea or as lasting more than 10 minutes using conventional laryngoscopy (4). The MACOCHA score enables patients at risk of difficult intubation to be identified and further reduce the incidence of difficult intubations and related complications (5).

Most of the patients in ICU may need endotracheal intubation because of hypoxia caused by acute respiratory failure and/or loss of consciousness due to neurological cause, and cardiogenic or septic shock. Neither the reason of admission nor the underlying reasons for Endotracheal intubation is predictors for difficult airway management. All patients in ICU requiring endotracheal intubation and mechanical ventilation will be included in the study.

Macocha Score grading will be compared with laryngeal view during direct laryngoscopy. The Cormack-Lehane classification is a grading system commonly used to describe laryngeal view during direct laryngoscopy. With this scale, a grade I view connotes a full view of the entire glottic aperture, grade II represents a partial glottic view, grade III represents visualization of the epiglottis only, and grade IV represents inability to visualize even the epiglottis