Biomedical subjects

P K S Lu

Publications and source records attributed to P K S Lu.

4 recordsLinked to original sources

PubMed2005

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

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.

Adult↗

PubMed2005

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.

Adult↗

PubMed2004

Quantitative computer-assisted digital-imaging upper airway analysis for obstructive sleep apnoea.

This was a prospective study of a new objective method which quantitatively analyses the upper airways in patients with obstructive sleep apnoea (OSA). Video-nasopharyngoscopic examinations of the upper airways of 45 patients were carried out with an endoscopic calibrator. Images of the upper airway during quiet respiration and Mueller's manoeuvre in erect and supine positions were digitized by computer to generate the actual dimensions of obstructive sites. Measurements by the new method were validated by comparing 90 pairs of videoendoscopic images with upper airway magnetic resonance imaging (MRI) measurements at two identical levels. Quantitative precision is 100% for the retropalatal level and 95.6% for the retrolingual level with a tolerance of 0.5 cm(2) between the two methods. The absolute mean of the difference between the two methods of measurement is 0.08 cm(2) at the retropalatal level and 0.18 cm(2) at the retrolingual level. The agreement between the digital-imaging videoendoscopic and MRI measurements was 93.3% for the retropalatal level and 95.6% for the retrolingual level. Quantitative computer-assisted digital imaging is a reliable, cost-effective clinical method of upper airway evaluation in OSA patients. This method allows us to examine the dynamic and static morphology objectively, measure surgical outcomes of upper airway, opening up new avenues for OSA management.

Body Mass Index↗

PubMed2002

Microbiology of chronic suppurative otitis media in Singapore.

The objective of the study was to study the microflora and the antibiograms of patients with chronic suppurative otitis media (CSOM) in Singapore. Ninety patients with CSOM were prospectively studied. They had chronic ear discharge and had not received antibiotics for the previous five days. Swabs were taken, and cultured for bacteria. Antibiotic testing was done using modified Kirby Bauer disk diffusion method. In addition to the usual antibiotics, the three most common topically available antibiotics (chloramphenicol, gentamicin and neomycin) were tested. There were 135 positive cultures for organisms from the 90 patients. The most common causal organisms isolated were Pseudomonas aeruginosa (33.3%) and Staphylococcus aureus (33.3%) followed by coagulase negative Staphylococcus (21.1%). Fungi accounted for 8.8% of isolates while 6.6% were anaerobes. Of the three antibiotics commonly available as topical eardrops, gentamicin has the highest susceptibility rate (82.6%), followed by neomycin (67.8%) and chloramphenicol (62.8%).

Adolescent↗