Injecting subcutaneous saline to bring arterial depth from < @ mm to @ to @ mm significantly shortened catheterization time ( P = @ ) , and improved the success rate in the first-attempt ( saline injection -LSB- @ % -RSB- vs < @ mm -LSB- @ % -RSB- , P < @ ) , and the overall attempt ( saline injection -LSB- @ % -RSB- vs < @ mm -LSB- @ % -RSB- , P = @ ) .