Randomized Controlled Trial Investigating the Impact of High-Flow Nasal Cannula Oxygen Therapy on Patients Undergoing Robotic-Assisted Laparoscopic Rectal Cancer Surgery, with a Post-Extubation Atelectasis as a Complication

Figures & data

Figure 1 Division of the hemithorax into 6 segments for lung ultrasound examination.

Abbreviations: PL, parasternal line; AAL, anterior axillary line; PAL, posterior axillary line.

Figure 2 Lung ultrasound images with different scores. (A) Normal pattern “bat-sign” with A-lines parallel to the pleural line, score = 0; (B) ≥3 B lines arising from pleural line, score = 1; (C) Multiple subpleural consolidations separated by an irregular pleural line, score = 2; (D) Large-sized consolidation, score = 3. Arrow indicates corresponding pathologic findings of each figure.

Table 1 Demographic Data and Surgical Details

	Control Group (n=39)	HFNC Group (n=39)	P value
Age (year)	68.74 ± 6.84	67.95 ± 6.57	0.60
Gender (male/female)	22/17	23/16	0.82
ASA classification (I/II/III)	3/27/9	4/28/7	0.81
BMI (kg/m^2)	23.01 ± 3.03	22.56 ± 2.74	0.49
Operation time (min)	169.44 ± 39.31	175.10 ± 39.92	0.53
Anesthesia time (min)	206.44 ± 40.23	210.59 ± 46.10	0.67
Total fluid intake (mL)	2050(1850–2200)	2150(1900–2250)	0.15
Total urine output (mL)	450(350–550)	500(300–600)	0.59

Notes: Values are presented as mean ± standard deviation, number, or median (interquartile range).

Abbreviations: ASA, American Society of Anesthesiologists; BMI, Body Mass Index.

Figure 3 Flowchart of participants.

Table 2 Lung Ultrasound Measurements at Different Time Points

	Control Group (n=39)	HFNC Group (n=39)	P value
Upon tracheal extubation (T1)
Total LUS score	10 (7–13)	11(8–12)	0.87
Significant atelectasis	34 (87.18%)	35 (89.74%)	0.72
At discharge of PACU (T2)
Total LUS score	10 (8–12)	5 (3–8)^a	< 0.001
Significant atelectasis	32 (82.05%)	19 (48.72%)^b	0.002

Notes: Values are presented as median (interquartile range) or number (%). Total LUS score is the summation of 12 thoracic regions^’ lung ultrasound scores. Significant atelectasis was defined as a score of ≥ 2 in any region. ^aSignificant compared to total LUS score at T1 in HFNC group. ^bSignificant compared to the incidence of atelectasis at T1 in HFNC group.

Abbreviation: PACU, Post-anesthesia care unit.

Table 3 Postoperative Variables Between the Control and HFNC Groups

	Control Group (n=39)	HFNC Group (n=39)	P value
PACU stay (min)	60.38±13.22	58.67±10.22	0.52
Desaturation in PACU	6 (15.38%)	0 (0%)	0.03
Minimum SpO2 in PACU (%)	97 (95–98)	99 (98–99)	< 0.001
Postoperative pneumonia	4 (10.26%)	2 (5.13%)	0.67
Length of hospitalization (day)	10 (9–12)	10 (9–11)	0.37

Notes: Values are presented as mean ± standard deviation, number (%), or median (interquartile range). Desaturation was defined as a SpO₂ < 95%.