Computer-assisted quantitative upper airway analysis following modified uvulopalatal flap and lateral pharyngoplasty for obstructive sleep apnoea: a prospective case-controlled study

OBJECTIVES

  The study aims to perform static and dynamic quantitative assessment of the anatomical changes of the upper airway before and after modified uvulopalatal flap and lateral pharyngoplasty and comparison of the improvement in airway dimensions, collapsibility and extent of normalisation to that of control patients.

DESIGN

  Prospective case-controlled study.

SETTING

  Computer-assisted quantitative measurement is used to compare upper airway parameters before and after modified uvulopalatal flap and lateral pharyngoplasty in patients with obstructive sleep apnoea (OSA).

PARTICIPANTS

  Patients with obstructive sleep apnoea diagnosed on sleep study and failed positive airway pressure therapy.

MAIN OUTCOME MEASURES

  Sleep study results, upper airway parameters and symptom score following surgery and its comparison to normal patients to assess the degree and extent of normalisation.

RESULTS

  Thirty-five study and 32 control subjects were recruited and completed the study. All the retropalatal airway dimensions like area, transverse diameter, longitudinal diameter and collapsibility showed statistically significant improvement following surgery. The success rate of this surgery is 43% (15 of 35) overall, 58% (14 of 24) for patients with isolated palatal obstruction and only 9% (1 of 11) for patients with multi-level obstruction. Comparing obstructive sleep apnoea to the control subjects, there are obvious and logical differences in their biostatistics, sleep study parameters and airway dimensions. The postoperative obstructive sleep apnoea retropalatal longitudinal diameter has a higher tendency of normalising to be comparable to those of control patients.

CONCLUSIONS

  Modified uvulopalatal flap and lateral pharyngoplasty is an effective surgical technique for the treatment of obstructive sleep apnoea. The surgery increases the resting retropalatal dimensions and reduces the retropalatal collapsibility.

10th Yahya Cohen Memorial Lecture: Clinical predictors in obstructive sleep apnoea patients with computer-assisted quantitative videoendoscopic upper airway analysis

AIM

To identify the clinical predictors and assist surgeons in their clinical management of obstructive sleep apnoea (OSA) - a prospective study with a new approach to analyse the static and dynamic upper airway morphology between patients with OSA and normal subjects. To introduce a new method of assessment for surgical outcome.

MATERIALS AND METHODS

Quantitative computer-assisted videoendoscopy (validated with upper airway magnetic resonance imaging) was performed in 49 (43 males, 6 females) patients with OSA and compared with 39 (22 males, 17 females) controls (apnoea-hypopnoea index <5). Absolute cross-sectional areas, transverse and longitudinal diameters at the retro-palatal and retro-lingual levels were measured during end of quiet respiration and during Mueller's manoeuvre in the erect and supine positions, allowing us to study static and dynamic morphology (collapsibility) of the upper airway. We analysed 3744 parameters.

RESULTS

In males, retro-palatal and retro-lingual areas during Mueller's manoeuvre in the supine position of 0.7981 cm2 [receiver operating characteristics (ROC) = 0.9284, positive predictive value (PPV) = 86.05%, negative predictive value (NPV) = 84.62%] and 2.0648 cm2 (ROC = 0.8183, PPV = 76%, NPV = 83.33%), respectively, were found to be good predictors/ cut-off values for OSA. Retro-palatal area measured in the supine position during Mueller's manoeuvre (AS1M) and collapsibility of retro-palatal area in the supine position calculated (CAS1) were found to have significant correlations with severity of OSA. In females, areas measured during Mueller's manoeuvre in the supine position of 0.522 cm2 at retropalatal level (ROC = 1, 100% PPV and NPV) and transverse diameter at retro-lingual level during erect Mueller's manoeuvre of 1.1843 cm (ROC = 0.9056, PPV = 100%, NPV = 83.33%) were found to be predictive. All measurements at the retro-palatal level and in the supine position had higher predictability. Area measurements obtained during Muller's manoeuvre were more predictive (ROC >0.9910) than resting measurements (ROC >0.8371). Several gender and anatomical-site specific formulas with excellent predictability (ROC close or equal to 1) were also devised. Examples of surgical outcome assessment were introduced.

CONCLUSION

Upper airway Mueller's studies are predictive and useful (independent samples t-test/Mann Whitney U test, ROC) in identifying patients with OSA. With these gender and anatomical-site specific OSA predictors/formulas and this innovative clinical method, we hope to assist other surgeons with quantitative clinical diagnosis, assessment, surgical planning and outcome assessment tools for OSA patients.

Clinical predictors in obstructive sleep apnoea patients with calibrated cephalometric analysis - a new approach1

AIM

Utilization of a new method to accurately quantify differences in cephalometric parameters between obstructive sleep apnoea (OSA) and normal patients, and to identify good predictors for OSA. To illustrate the ethnic differences in cephalometry.

METHOD

This prospective study involves 106 South-east Asians. A calibrated catheter is inserted into the upper airway during standard cephalometry to obtain the precise magnification and allow exact measurement of anatomical parameters of cephalometry in both erect and supine positions.

RESULTS

The OSA patients have longer lower-facial length, narrower skull base, shorter and receding mandible, smaller posterior airway space (PAS), narrower retropalatal space, longer and thicker soft palate, smaller hard and soft palate angles longer tongue length and more inferiorly displaced hyoid. For the palatal level, retropalatal distance of 11.2 mm cut-off/predictive value for male (receiver operating characteristics (ROC) = 0.8414 with PPV = 77.46, NPV = 90.00) and 5.5 mm for female (ROC = 0.9180 with PPV = 100.00, NPV = 84.21) at erect position were selected. For retrolingual level, erect PAS of 10.1 mm cut-off/predictive value for male (ROC = 0.7000 with PPV = 78.38, NPV = 37.78), 5.3 mm for female (ROC = 0.7227 with PPV = 75.00, NPV = 75.00) were selected. Our study showed that South-east Asians have different cephalometric values compared with White people, Black people and Hispanics.

CONCLUSION

This new method of cephalometry using a calibrated catheter provides an accurate and simple method of obtaining precise cephalometric measurements. There is no cephalometric data on OSA from South-east Asia available. These results suggested that surgeons managing OSA patients and using cephalometry as a diagnostic method should have a set of normative and OSA cephalometric values that apply to their local populations.