大手术中笑气的应用思考课件

1、大手术中笑气的应用思考Paul S. Mules, et al:Department of Anaesthesia and Perioperative MedicineMonash University, Melbourne, AUSTRALIAAnesthesiology 2007; 107:22131BackgroundNitrous oxide may irreversibly inhibit vitamin B12, which explains reports of megaloblastic(巨红细胞) anemia and neurologic toxicity with pro

2、longed administration, and a possible increased risk of teratogenicity(致畸), immunodeficiency, and impaired wound healing. Nitrous oxide increases plasma homocysteine(半胱氨酸) concentrations which may increase the risk of postoperative cardiovascular complications.Nitrous oxide impairs cerebral blood fl

3、owactivity coupling and worsens air space conditions and bowel distension.Nitrous oxide is a proven risk factor for postoperative nausea and vomiting.Nitrous oxide prevents the use of high inspired oxygen concentrations. Evaluate whether avoidance of nitrous oxide, an intervention that avoids potent

4、ial nitrous oxide toxicity and in addition allows an increase in the inspired oxygen fraction, could decrease the duration of hospital stay after surgery and reduce postoperative complications, nitrous oxide-free compared with a nitrous oxidebased anesthetic regimen in adult patients presenting for

5、major surgery. PurposeRandomly (using a computer-generated code, accessed via an automated telephone voice recognition service)blind (patients, surgeons, research staff conducting the postoperative follow-ups) multicenter (19 participating sites around the world)Groups: nitrous oxidefree anesthesia(

6、 a gas mixture of 80% oxygen with 20% nitrogen) and nitrous oxidebased anesthesia( a gas mixture of 70% nitrous oxide with 30% oxygen from after induction of anesthesia to completion of surgery)Adjustment for age, ASA physical status, duration of anes.Materials and MethodsIndexsThe primary endpoint:

7、 the duration of hospital stay defined as the duration from the start of surgery until actual hospital discharge.Duration of stay in ICU.Postoperative complications (Wound infection, Pneumonia, Fever, Pulmonary atelectasis, Pneumothorax, Severe nausea and vomiting, Myocardial infarction, stroke, awa

8、reness, Venous thromboembolism, Blood transfusion, Quality of recovery at 24 h after surgery, Death) occurring in the first 30 postoperative days.Preoperative demographic characteristics and details of patient medical and surgical history.ResultsResultsThe median duration of ICU stay was 1 day in ea

9、ch groupResultsPatients in the nitrous oxidefree group had a lower incidence of several postoperative complications, including severe nausea or vomiting, fever, wound infection, pneumonia, and atelectasis. Were less likely to have at least one major complication.Patients in the nitrous oxidefree gro

10、up had better quality of recovery scores than patients in the nitrous oxide group. And it was unaffected after adjustment for age, ASA, sex, etc. The incidence of severe nausea or vomiting within 24 h of surgery in our study was reduced from 23% in the nitrous oxide group to 10% in the nitrous oxide

11、free group.ResultsDiscussionsThe study did not observe a meaningful difference in duration of hospital stay between groups.Hospital stay can be affected by non-clinical factors and variable local practices. Some postoperative complications are transient or can be readily treated and so may not affec

12、t hospital stay.This view can be supported by figure 2, which indicates no apparent difference between groups within the first 7 days after surgery, but that a difference may exist in those staying longer than 7 days, possibly because of increased postoperative complications.The decreased risk of co

13、mplications in the nitrous oxidefree group of our study could be explained by avoidance of nitrous oxide and/or administration of high inspired oxygen concentrations.Nitrous oxide promotes absorption atelectasis in the lung as effectively as breathing 100% oxygen, and we found a higher rate of atele

14、ctasis in the nitrous oxide group.We found no evidence that oxygen concentration affected our main outcomes in the nitrous oxidefree group, but this exploratory analysis was limited by the small number (n=156) of patients receiving inspired oxygen concentration of less than 51%.DiscussionsOur study

15、found a marked reduction in the rate of severe nausea or vomiting in the first 24 h after surgery in the nitrous oxidefree group. We found that a nitrous oxidefree anesthetic was associated with less myocardial infarction and death, but these were not statistically significant. This could be a type

16、II error because our study was not of sufficient size.Inclusion of nitrous oxide allows a dose reduction of other hypnotic agents, but patients receiving a nitrous oxidefree anesthetic were eligible for discharge from the post anesthesia care unit slightly faster than those receiving nitrous oxide.

17、And we found that avoidance of nitrous oxide did not increases the risk of awareness.DiscussionsConclusionsAvoidance of nitrous oxide combined with supplementary oxygen in the gas mixture for anesthesia decreases the incidence of complications after major surgery but does not significantly affect duration of hospital stay. Whether the re