Tehran University Medical Journal

Background: The major responsibility of an anesthesiologist is to provide adequate respiration for the patient. The most vital element in providing functional respiration is the airway. No anesthetic is safe unless diligent efforts are devoted to maintaining an intact functional airway. Difficult intubation had been classified into four grades, according to the view obtainable at laryngoscopy by Cormack and Lehane in 1984. This grading system has been in use to evaluate and manage those patients with difficult airway by anesthesiologists. In clinical state, grades III and IV are quite rare, so the need for a modified Cormack and Lehane grading system was felt. The use of a modified Cormack-Lehane scoring system of laryngoscopic views during direct laryngoscopy, was previously examined in the Western population. Koh and his co-workers had examined this modified Cormack and Lehane grading system in Asian population in a study in Singapore General Hospital. The aim of this study was to investigate this scoring system in Iranian patients.

Methods: In a cross sectional study, a modified version of the Cormack and Lehane grading system was evaluated in 300 patients requiring tracheal intubation. In the modified system, grade II (only part of the glottis is visible) was divided into IIa (part of the cords is visible) and IIb (only the arytenoids or the very posterior origin of the cords are visible). Difficult intubation was defined as requiring more than one laryngoscopy or the use of special equipments.

Results: Sixty eight patients (22.7%) were scored as grade IIa and 32 (7.7%) as grade IIb. The prevalence of difficult intubation in grade IIb was significantly higher than patients in group IIa (47.8% vs. 2.9% respectively, Fisher's exact test, p= 0.001)

Conclusion: The modified grading system provides more information than the original Cormack and Lehane system.

Background: The risk of atherosclerosis and cancer is high in hemodialysis (HD) patients. There is evidence that HD causes oxidative stress. However, the causative factors of oxidative stress are unknown. It has been suggested that HD imposes an additional oxidative stress on patients with chronic renal failure by activation of granulocytes on dialyzer membranes resulting in an imbalance between oxidants and antioxidants. In this regard, a number of reports, either measuring specific analytes or enzymes, or estimating the total antioxidant activity of the plasma have given contradictory and inconclusive results. To investigate the oxidative stress status in Iranian HD patients, in this study, we evaluated GSH and FRAP levels along with Ca and pH in the blood of these patients.

Methods: Along with 20 healthy age and gender matched control subjects, 24 patients underwent dialysis, three times per week, for four hours in each session. Before and after dialysis, blood was taken for biochemical and liver function tests and to evaluate oxidative stress markers and measure Ca and pH levels.

Results: There was a significant decrease in FRAP and GSH levels after dialysis compared to those before treatment. Dialysis caused an increase in pH and Ca levels compared to levels in control subjects after dialysis.

Conclusion: In general, before dialysis, there is a balance between oxidants and antioxidants however, due to higher levels of oxidants as well as the possible binding of antioxidants to the dialyzer membrane during dialysis, an imbalance occurs. The instability in the balance of oxidants and antioxidants may be the major cause of cellular oxidative damage found in HD patients. This study indicates that there is a significant level of oxidative stress in renal chronic patients and this stress is augmented by dialysis. Antioxidant therapy should be considered in these patients.

Normal 0 false false false EN-GB X-NONE AR-SA MicrosoftInternetExplorer4 Background: The ability of a specific test to predict a difficult intubation is decreased by the variability of definitions of difficult intubation/laryngoscopy. The Mallampati classification system is a widely utilized approach for evaluating patients in the preoperative setting. Zero class of Mallampati is a new class of airway view that to add to the four modified Mallampati classes. This study estimates the incidence of class zero airway and determines the ability of Mallampati score, age and sex on the prediction of the larangoscopy grade.
Methods: This is a cross sectional study in which 376 patients aged 7-18 years and A.S.A physical status I or II were enrolled. They were scheduled for surgery under general anesthesia All the airway assessments were done in the sitting position, with the patient's head in neutral position, mouth fully open, tongue fully extended and without phonation. After induction of general anesthesia, laryngoscopy grade was assessed in sniffing position using the Cormak & Lehame grading scale.
Results: Class zero airways occurred in 0.3% of patients, and the patients with class zero airway had a grade I laryngoscopy. 49.5% of patient had class I, 37.2% class II, 13% of patient had class III and there found no patient with class IV airway. Grade II and III laryngoscopy were more frequent in females than in males but this correlation was not statistically significant. 
Conclusions: Assessment of airway by Mallampati scoring system and attention to the age can be an important factor in the prediction of high laryngoscopy grade.

Normal 0 false false false EN-GB X-NONE AR-SA MicrosoftInternetExplorer4 Background: The prediction of the probability of difficult intubation and the associated problems before Induction of anesthesia could be lifesaving. The aim of this study was the investigation of association between the stage of thyroid cartilage prominency and laryngoscopic view for predicting the difficult intubation.
Methods: Five hundred and thirty five patients aged 18-60 years old, with prominent thyroid cartilage, "Adam's apple", enrolled in a cross -sectional study based on the stage of "Adam's apple" and the relationship with laryngoscopic view. After induction of anesthesia, laryngoscopy performed and laryngoscopic view of larynx was recorded, and analyzed according to Modified Cormackand Lehane's Scoring.
Results: No significant association between laryngoscopic view and thyroid cartilage prominency staging was observed. There was no significant relationship in females and aged under 50 y.o. The relationship in males with poor correlation coefficient was significant. The results are as follows: [male :(p=0.028, r=-0.096), Female: (p=0.821, r=0.082), <50 yrs: (p=0.87, r=0.007) no significant association for age decades and thyroid cartilage prominency stages, were observed. In ages above 50 y.o, difference was significant. Thirty patients had a laryngoscopic view in which the tracheal rings were visible just bellow the vocal cords.
Conclusions: As the increased age was related to laryngoscopic view and thyroid cartilage prominency stage it seems that there is relationship between ages over 50 y.o and difficulty of laryngoscopic view or intubation. With the observation of a view different from the grade I Cormack and Lehane's scoring, we named it the "stage Ia" that the tracheal rings are visible bellow the vocal cords during laryngoscopy.