Lars Tue Sørensen

Abstinence from smoking reduces incisional wound infection: A randomized controlled trial

Objective Clinical studies show that the incidence of postoperative wound complications is higher in smokers than nonsmokers. In this study, we evaluated the effect of abstinence from smoking on incisional wound infection. Methods Seventy-eight healthy subjects (48 smokers and 30 never-smokers) were included in the study and followed for 15 weeks. In the first week of the study, the smokers smoked 20 cigarettes per day. Subsequently, they were randomized to continuous smoking, abstinence with transdermal nicotine patch (25 mg per day), or abstinence with placebo patch. At the end of the first week and 4, 8, and 12 weeks after randomization, incisional wounds were made lateral to the sacrum to excise punch biopsy wounds. At the same time identical wounds were made in 6 never-smokers. In 24 never-smokers a wound was made once. All wounds were followed for 2 weeks for development of wound complications. Results A total of 228 wounds were evaluated. In smokers the wound infection rate was 12% (11 of 93 wounds) compared with 2% (1 of 48 wounds) in never-smokers (P <0.05). Wound infections were significantly fewer in abstinent smokers compared with continuous smokers after 4, 8, and 12 weeks after randomization. No difference between transdermal nicotine patch and placebo was found. Conclusions Smokers have a higher wound infection rate than never-smokers and 4 weeks of abstinence from smoking reduces the incidence of wound infections.

Wound healing and infection in surgery. The clinical impact of smoking and smoking cessation: a systematic review and meta-analysis

OBJECTIVES To clarify the evidence on smoking and postoperative healing complications across surgical specialties and to determine the impact of perioperative smoking cessation intervention. DATA SOURCES Cohort studies and randomized controlled trials. STUDY SELECTION Selected studies were identified through electronic databases (CENTRAL, MEDLINE, and EMBASE) and by hand searching. DATA EXTRACTION Multiple data on study characteristics were extracted. Risk of bias was assessed by means of the Newcastle-Ottawa Scale and Jadad score. Healing outcome was classified as necrosis, healing delay and dehiscence, surgical site infection, wound complications, hernia, and lack of fistula or bone healing. Mantel-Haenszel and inverse variance methods for meta-analysis (fixed- and random-effects models) were used. DATA SYNTHESIS Smokers and nonsmokers were compared in 140 cohort studies including 479,150 patients. The pooled adjusted odds ratios (95% CI) were 3.60 (2.62-4.93) for necrosis, 2.07 (1.53-2.81) for healing delay and dehiscence, 1.79 (1.57-2.04) for surgical site infection, 2.27 (1.82-2.84) for wound complications, 2.07 (1.23-3.47) for hernia, and 2.44 (1.66-3.58) for lack of fistula or bone healing. Former smokers and patients who never smoked were compared in 24 studies including 47,764 patients, and former smokers and current smokers were compared in 20 studies including 40,629 patients. The pooled unadjusted odds ratios were 1.30 (1.07-1.59) and 0.69 (0.56-0.85), respectively, for healing complications combined. In 4 randomized controlled trials, smoking cessation intervention reduced surgical site infections (odds ratio, 0.43 [95% CI, 0.21-0.85]), but not other healing complications (0.51 [0.22-1.19]). CONCLUSIONS Postoperative healing complications occur significantly more often in smokers compared with nonsmokers and in former smokers compared with those who never smoked. Perioperative smoking cessation intervention reduces surgical site infections, but not other healing complications.

Risk Factors for Tissue and Wound Complications in Gastrointestinal Surgery

Background:Surgical site infections and disruption of sutured tissue are frequent complications following surgery. We aimed to assess risk factors predictive of tissue and wound complications in open gastrointestinal surgery. Methods:Data from 4855 unselected patients undergoing open gastrointestinal surgery from 1995 through 1998 were recorded in a clinical database and validated. The database embraced variables related to patient history, preoperative clinical condition, operative findings and severity, and the surgeons training. Variables predictive of surgical site infection and dehiscence of sutured tissue within 30 days after surgery were assessed by multiple logistic regression analysis. Results:Following elective operation, the incidence of tissue and wound complications was 6% compared with 16% in emergency surgery (P < 0.001). These complications resulted in prolonged hospitalization in 50% of the patients and a 3-fold higher risk of reoperation but not increased mortality. Factors associated with complications following elective operations were smoking, comorbidity, and perioperative blood loss. Following emergency operations, male gender, peritonitis, and multiple operations were predictors of complications. Irrespective of elective or emergency surgery, the type of operation was a predictor of complications. Conclusion:Factors known to affect the process of tissue and wound healing are independently associated with tissue and wound complications following gastrointestinal surgery.

Smoking is a risk factor for recurrence of groin hernia.

Studies of connective tissue from patients with inguinal hernia have shown that smoking may be associated with hernia formation due to a defective connective tissue metabolism. Whether smoking is a risk factor for recurrence, too, was examined in this study. From December 1990 through December 1995, 649 patients underwent hernia repair as open sutured repair (Cooper ligament or abdominal ring repair) or as open mesh repair. Five hundred forty-four eligible patients were evaluated for recurrence 2 years postoperatively. Association between recurrence and 17 patient-, disease-, and intraoperative variables were analyzed by multiple logistic regression. The results showed that smoking was significantly and independently associated with recurrence compared to nonsmoking [odds ratio (OR = 2.22; 95% confidence interval (95% CI) = 1.19–4.15)]. Open sutured repair compared to open mesh repair was the most significant predictor for recurrence (OR = 7.23; 95% CI = 3.01–17.37). Surprisingly, local anesthesia was associated with a higher risk of recurrence compared to general anesthesia (OR = 2.44; 95% CI = 1.19–5.09). Potential confounders and other risk factors for hernia recurrence such as age, alcohol consumption, previous surgery, and anatomical characteristics of the hernia were adjusted for in the analysis. In conclusion, smoking is an important risk factor for recurrence of groin hernia, presumably due to an abnormal connective tissue metabolism in smokers.

Short-term pre-operative smoking cessation intervention does not affect postoperative complications in colorectal surgery: a randomized clinical trial.

Background  Smokers have a higher risk of complicated tissue and wound healing after surgery than nonsmokers. We tested the hypothesis that short‐term pre‐operative cessation of smoking in colorectal surgery decreases the incidence of postoperative tissue and wound complications.

Acute effects of nicotine and smoking on blood flow, tissue oxygen, and aerobe metabolism of the skin and subcutis.

BACKGROUND Nicotine released from tobacco smoke causing reduction in blood flow has been suggested as causative for postoperative wound complications in smokers, but the mechanism remains unknown. MATERIALS AND METHODS In eight healthy male smokers and eight ex-smokers, the cutaneous and subcutaneous blood flow (QBF, SqBF) was assessed by Laser Doppler and 133Xe clearance. Tissue oxygen tension (TO(2)) was measured by a LICOX O(2)-electrode. Tissue glucose and lactate (Tgluc, Tlact) were assessed by microdialysis. The parameters were studied after intravenous infusion of 1.0 mg nicotine, smoking of one cigarette, arterial occlusion, and reperfusion. RESULTS Nicotine infusion decreased SqBF from 4.2 +/- 2.0 to 3.1 +/- 1.2 mL/100 g tissue/min (P < 0.01), whereas QBF was 21.7 +/- 8.6 and 22.7 +/- 9.6 Arbitrary Units (AU), respectively (P = 0.21). TO(2) increased from 49.3 +/- 12.0 to 53.9 +/- 12.0 mm Hg (P = 0.01). Tgluc and Tlact remained unaffected. Smoking decreased SqBF from 4.2 +/- 2.0 to 2.7 +/- 1.2 mL/100 g tissue/min (P < 0.01). QBF decreased from 23.4 +/- 9.2 to 20.3 +/- 7.4 AU (P < 0.01), and TO(2) decreased from 53.9 +/- 12.0 to 48.4 +/- 11.1 mm Hg (P < 0.01). Following smoking, Tgluc decreased from 0.7 +/- 0.1 to 0.6 +/- 0.1 ng/mL (P < 0.01), and Tlact increased from 0.2 +/- 0.1 to 0.3 +/- 0.2 ng/mL (P < 0.01). The observed alterations were similar in smokers and ex-smokers. CONCLUSIONS Nicotine has a limited vasoactive effect in the skin and subcutis unlikely to be explained by smoking, which distinctly decreases tissue blood flow, oxygen tension, and aerobe metabolism independent of smoking status.

Connective tissue alteration in abdominal wall hernia.

The aetiology and pathogenesis of abdominal wall hernia formation is complex. Optimal treatment of hernias depends on a full understanding of the pathophysiological mechanisms involved in their formation. The aim of this study was to review the literature on specific collagen alterations in abdominal wall hernia formation.

Laparoscopic surgery compared with open surgery decreases surgical site infection in obese patients: a systematic review and meta-analysis.

Objective:To compare surgical site infections rate in obese patients after laparoscopic surgery with open general abdominal surgery. Background:In mixed surgical populations, surgical site infections are fewer in laparoscopic surgery than in open surgery. It is not clear if this is also the case for obese patients, who have a higher risk of surgical site infections than nonobese patients. Methods:MEDLINE, Embase, and The Cochrane library (CENTRAL) were searched systematically for studies on laparoscopic surgery compared with open abdominal surgery. Randomized controlled trials (RCTs) and observational studies reporting surgical site infection in groups of obese patients (body mass index ≥ 30) were included. Separate meta-analyses with a fixed effects model for RCTs and a random effects model for observational studies were performed. Methodological quality of the included studies was assessed according to the Cochrane method and the Newcastle-Ottawa Scale. Results:Eight RCTs and 36 observational studies on bariatric and nonbariatric surgery were identified. Meta-analyses of RCTs and observational studies showed a significantly lower surgical site infection rate after laparoscopic surgery (OR = 0.19; 95% CI [0.08-0.45]; P = 0.0002 and OR = 0.33; 95% CI [0.26-0.42]; P = 0.00001). Sensitivity analyses to assess the impact of selection and detection bias confirmed the significant estimates with acceptable heterogeneity. No publication bias was present for the observational studies. Conclusions:Laparoscopic surgery in obese patients reduces surgical site infection rate by 70%–80% compared with open surgery across general abdominal surgical procedures. Future efforts should be focused on further development of laparoscopic surgery for the growing obese population.

Effect of lifestyle, gender and age on collagen formation and degradation

Historically, inappropriate lifestyle with an inadequate dietary intake of vitamin C has been associated with poor wound healing as a clinical manifestation of scurvy. In modern times, clinical evidence produced over the past few decades indicates that a modern lifestyle factor, such as smoking, together with biologic characteristics, like old age and male gender, are risk factors for abdominal wall hernia and recurrence. The pathologic pathways for these clinical observations are unclear. Yet, evidence from animal and human studies suggests that these exogenous and endogenous factors may have a negative impact on collagen metabolism, enhancing degradation and impairing formation.

Transdermal nicotine patch enhances type I collagen synthesis in abstinent smokers

Cigarette smokers deposit less collagen, expressed as hydroxyproline, in granulation tissue than nonsmokers. We studied the effect of abstinence from smoking and transdermal nicotine patches on deposition of hydroxyproline, proline, type I procollagen, and total proteins. Fifty‐four healthy smokers were studied during 10 days of smoking and again from days 10 to 20 following smoking cessation. After the first 10 days of abstinence they were randomized to double‐blind treatment with transdermal nicotine patches of 25 mg/day or placebo for a period of 10 days. During this period and during smoking, an expanded polytetrafluoroethylene tube was implanted into the subcutis. Following removal of the implant, total amino acids and peptides were extracted. Hydroxyproline and proline were analyzed by high‐pressure liguid chromatography, type I procollagen was analyzed by enzyme‐linked immunoassay, and total proteins were determined colorimetrically. In the 39 subjects who complied with the study protocol, abstinence from smoking did not affect the deposition of hydroxyproline, proline, type I procollagen, or total protein in the implants. During abstinence, the type I procollagen level increased by 18% in the transdermal nicotine patches group and decreased by 10% in the placebo group (p<0.05). We conclude that 20 days of abstinence from smoking does not affect collagen deposition in granulation tissue. However, in abstinent smokers, transdermal nicotine patches appears to increase type I collagen synthesis.