Table 2.
Comparison between traditional cigarettes and e-cigarettes
| Components | Traditional cigarettes | Electronic cigarettes |
|---|---|---|
| Major constituents | Nicotine | Nicotine |
| Carbon monoxide | Propylene glycol | |
| Nitrosamines | Glycerol | |
| Aromatic hydrocarbons | Flavoring | |
| Aldehydes | ||
| >4,000 Chemical compounds | ||
| Effects on inflammatory cells | Increase in inflammatory cytokines, such as IL-1 and TNF-alpha | No increase in WBC |
| Increase number and reactivity of neutrophils in the blood stream | Decreased density and viability of Kupffer cells | |
| Decrease in neutrophil and monocyte chemotaxis | Increase complement protein activation and deposition onto liver Kupffer cells | |
| Decrease in neutrophil and macrophage migration into wounded issue | Enhanced C1q receptor expression on Kupffer cells | |
| Decrease in neutrophil and macrophage oxidative burst and phagocytic activity, resulting in decreased ability to clear wounds of bacteria | Increase Kupffer cell cytokine release | |
| Increase in proteolytic enzymes (specifically MMP-8 and MMP-9) leading to increased collagen degradation and weaker wound strength | Enhanced hydrogen peroxide production due to increased xanthine oxidase and peroxidase activity | |
| ROS inhibit anti-proteases | Decreased epithelial cell, alveolar macrophage and neutrophil anti-microbial activity against staph aureus | |
| Upregulation of certain inflammatory markers and acute phase reactants | ||
| Some vapor extracts promote ROS formation | ||
| Effects on cellular proliferation and wound healing process | Reduced fibroblast proliferation | Enhanced epithelial cell death with exposure to vapor extract |
| Reduced pro-collagen (I and III) and collagen (I and III) synthesis | Decreased endothelial cell proliferation | |
| Reduced hydroxyproline accumulation | Increased DNA strand breaks in epithelial and squamous cell lines exposed to e-cigarette vapor, with or without nicotine | |
| Likely reduced endothelial angiogenesis | ||
| Reduced epidermal regeneration with thinner epidermis and stratum corneum and reduced epidermal barrier | ||
| Reduced levels of Vitamin C and E, with reduced ability to clear ROS and increased defective collagen synthesis | ||
| ROS contribute to increased destruction of cell membranes, endothelial dysfunction and cellular apoptosis | ||
| Effects on clotting cascade | Increase in platelet activation | Largely unknown |
| Increase circulating fibronectin | ||
| Overall increased propensity to form blood clots | ||
| Effects on blood vessels | Oxidative stress on endothelial cells | Cytotoxic to endothelial cells, whether or not vapor contains nicotine |
| Induces vasoconstriction | Morphologic alterations to endothelial cells, including disruptions to endothelial cell barrier and cell-to-cell contacts | |
| Inhibits endothelial-dependent vasodilation | ||
| Stimulates catecholamine release and adrenergic stimulation contributing to vasoconstriction | ||
| Effects on tissue oxygenation | Vasoconstriction induces hypoxia | Reduced cutaneous blood flow |
| Decreased subcutaneous blood flow | ||
| Decreased tissue oxygen tension | ||
| Increased lactate levels and anaerobic metabolism in tissue | ||
| Carbon monoxide shifts oxygen dissocation curve to the left and has 200 times higher affinity for hemoglobin, decreasing oxygen delivery to peripheral tissues | ||
| Cardiovascular effects | Accelerated atherosclerotic disease | Smokers switching to e-cigarettes with elevated systolic blood pressure at baseline demonstrate a decrease in systolic blood pressure after 1 year of smoking cessation with e-cigarette use |
| Increased risk of CAD and MI | ||
| Pulmonary effects | Increased risk of lung cancer | Increased dynamic airway resistance |
| Increased risk of COPD and other lung disorders | Increased expired NO | |
| Airway colonizer staph aureus demonstrates increased virulence, biofilm formation and enhanced invasion of host epithelial cells when exposed to vapor extract | ||
| Associated surgical complications | SSI | Increased distal skin flap necrosis in rats |
| Delayed wound healing | Largely unknown in humans | |
| Wound dehiscence | ||
| Incisional hernia | ||
| Skin flap necrosis | ||
| Tissue flap necrosis |
IL-1, interleukin 1; TNF-alpha, tumor necrosis factor-alpha; WBC, white blood cell; MMP, matrix metalloproteinase; ROS, reactive oxygen species; CAD, coronary artery disease; MI, myocardial infarction; COPD, chronic obstructive pulmonary disease; NO, nitric oxide; SSI, surgical site infection.