Table 1: Studies about the incidence of Difficult Tracheal Intubation (DTI)

Study

No. of patients

Subjects

Diagnostic criteria for DTI

Type of Laryngoscope Blade

No. of Patients with Difficult intubation

Incidence of DTI (%)

Keith Rose et al. 1994 [28]

18.205

General population

Cormack and Lehane grade III or IV or 2 or more attempts

Macintosh

326

1.8

Keith Rose et al. 1996 [29]

3.325

General population

Cormack and Lehane grade III or IV

Macintosh

336

10.1

Keith Rose et al. 1996 [29]

3.325

General population

Three or more attempts

Macintosh

63

1.9

El-Ganzouri et al. 1996 [7]

10.507

General population

Cormack and Lehane grade III or IV

Macintosh and Miller

642

6.1

Arné et al, 1998 [20]

1.200

Surgery for ENT and general population

Unusualtechniquesperformed by twoAnesthesiologists

Macintosh

50

4.2

Adnet et al. 2001 [30]

1.171

General population

IDS more than 5

Macintosh

94

8

Iohom et al. 2002 [31]

212

General population

Cormack and Lehane grade III or IV

Macintosh

20

9

Gupta et al. 2003 [32]

372

Obstetric population

Cormack and Lehane grade III or IV

Macintosh

25

6.7

Ezri et al. 2003 [33]

1.472

Morbidly obese and non-obese

Cormack and Lehane grade III or IV

Macintosh

152

10.3

Combes et al. 2004 [34]

11.257

General population

More than two attempts

Macintosh

100

0.9

Cattano et al. 2004 [35]

1.956

General population

Cormack and Lehane grade III or IV or 3 or more attempts

Macintosh

28

1.4

Connelly et al. 2006 [11]

168.000

General population

Anesthesiologist discretion

Macintosh

446

0.26

Yildiz et al. 2007 [22]

1.674

General population

Cormack and Lehane grade III or IV

Macintosh

80

4.8

Tse et al. 2007 [36]

471

General population

Cormack and Lehane grade III or IV

Macintosh

61

13

Aftab et al. 2008 [37]

150

General population

No. of attempts+ Cormack and Lehane grade. Score more than 4

Macintosh

4

2.6

McDonnell et al. 2008 [38]

1.095

Obstetric population

More than one attempt

Macintosh

36

3.3

L’Hermite et al. 2009 [39]

1.024

General population

IDS more than 5

Macintosh

61

6

Kalezić et al. 2009 [40]

2.000

Tyroid surgery

Cormack and Lehane grade III or IV

Macintosh

110

5.5

Tao et al. 2012 [41]

2.158

Obstetric population

More than 3 attempts and/or additional techniques

Obstetric population

12

0.56