V. Leroy Young

Prevention of Perioperative Hypothermia in Plastic Surgery

While inadvertent perioperative hypothermia has received serious attention in many surgical specialties, few discussions of hypothermia have been published in the plastic surgery literature. This article reviews the physiology of thermoregulation, describes how both general and regional anesthesia alter the normal thermoregulatory mechanisms, indicates risk factors particularly associated with hypothermia, and discusses the most effective current methods for maintaining normothermia. Hypothermia is typically defined as a core body temperature of </=36 degrees C (</=96.8 degrees F), though patient outcomes are reportedly better when a temperature of >/=36.5 degrees C is maintained. Unless preventive measures are instituted, inadvertent hypothermia occurs in 50% to 90% of surgical patients, even those undergoing relatively short procedures lasting one to one-and-a-half hours. During either general or regional anesthesia, a patients natural behavioral and autonomic responses to cold are unavailable or impaired, and the combination of general and neuraxial anesthesia produces the highest risk for inadvertent perioperative hypothermia. Unless hypothermia is prevented, the restoration of normothermia can take more than 4 hours once anesthesia is stopped. Consequences of hypothermia are serious and affect surgical outcomes in plastic surgery patients. Potential complications include morbid cardiac events, coagulation disorders and blood loss, increased incidence of surgical wound infection, postoperative shivering, longer hospital stays, and increased costs associated with surgery. Measures for preventing hypothermia are emphasized in this article, especially those proven most effective in prospective and controlled clinical studies. Perhaps the most important step in maintaining normothermia is to prewarm patients in the preoperative area with forced-air heating systems. Intraoperative warming with forced-air and fluid warming are also essential. Other strategies include maintaining an ambient operating room temperature of approximately 73 degrees F (22.8 degrees C), covering as much of the body surface as possible, and aggressively treating postoperative shivering. None of these measures can be adequately employed unless a patients core body temperature is monitored throughout the perioperative period. Prevention of perioperative hypothermia is neither difficult nor expensive. Proper preventive measures can reduce the risk of complications and adverse outcomes, and eliminate hours of needless pain and misery for our patients.

Biodurability of retrieved silicone gel breast implants.

This study analyzed the shells of single-lumen silicone gel breast implants within the general context of device durability in vivo. The investigation included the major types of gel-filled implants that were manufactured in the United States in a 30-year period. The implants analyzed were Cronin seamed (two explants and one control), Silastic 0 and Silastic I (18 explants and seven controls), and Silastic II (22 explants and 43 controls). The biodurability of the explants was investigated with measurements of the mechanical and chemical properties of the various types of silicone gel control and explanted shells, with implantation times ranging from 3 months to 32 years. The shell properties measured for the controls and explants included the stress-strain relationships, tensile strength, elongation, tear resistance, moduli, cross-link density, and amount of extractable material in the shell. In addition, the mechanical properties of shells that had been extracted with hexane were analyzed for both explants and control implants. The silicone gel explants investigated in this study included some of the oldest explants of the various major types that have been tested to date. For assessment of long-term implantation effects, the data obtained in this study were combined with all known data from other institutions on the various major types of gel implants. The study also addressed the failure mechanisms associated with silicone gel breast implants. The results of the study demonstrated that silicone gel implants have remained intact for 32 years in vivo and that degradation of the shell mechanical and chemical properties is not a primary mechanism for silicone gel breast implant failure.

Variability in the properties of silicone gel breast implants.

Several generations of silicone gel breast implants have been produced by implant manufacturers. The primary material usually viewed as the base material in the manufacture of implants is polydimethylsiloxane. Polymeric reactions are notorious for their variability and nonuniformity. The elastomer used in different types of implants can have vastly different properties. Furthermore, the material properties associated with a particular type of implant can vary considerably from one lot to the next. Considering the various designs, styles, and manufacturing techniques associated with silicone gel implants, knowledge of the original properties of the implants before implantation is important in determining the effects of aging in vivo. This study was conducted to investigate differences in key mechanical and chemical properties of silicone gel breast implant materials. The two types of implants chosen for analysis were Silastic I and Silastic II control implants. Material property data were determined for both types of controls and significant differences were found in their values. Lot‐to‐lot variability was also investigated and found to be significant. (Plast. Reconstr. Surg. 108: 647, 2001.)

In vivo aging characteristics of silicone gel breast implants compared to lot-matched controls.

&NA; A study was conducted to investigate the effect of in vivo aging on the physical, mechanical, and chemical properties of Silastic II gel‐filled breast implants. In the study, the properties of 16 Silastic II gel‐filled explants (retrieved from eight patients), with in vivo duration times ranging from 4 months to 13 years, were compared with lot‐matched control (unimplanted) samples. Tensile and tear strength properties were measured for both explant and control shells by using identical testing protocols. The tensile strength properties of shells, which were extracted with hexane to remove noncross‐linked silicones, were also measured. Swelling measurements were used to determine the average molecular weight between cross‐links (or entanglements). In addition, scanning electron microscopy was applied in the comparison of the morphological features of the explants and their lotmatched controls. The results of the study suggest that the silicone polymer used to fabricate the shells does not undergo appreciable degradation for up to 13 years in vivo. The study represents an investigation of the worlds largest known inventory of explanted breast implants with lot‐matched controls. (Plast. Reconstr. Surg. 109: 1927, 2002.)

Scanning electron microscopy characterization of surgical instrument damage to breast implants.

In this article, mechanisms of breast‐implant failure caused by surgical instruments commonly used to perform implantation, breast biopsies, needle localization procedures, cyst aspirations, and explantation are described. Failure was artificially induced in breast‐implant shells using various types of surgical instruments, including scalpels, suture needles, hypodermic needles, hemostats, and Adson forceps. Field‐emission scanning electron microscopy (SEM) was used to document the morphology of the failure sites produced by these instruments. Micrographs were used to categorize failure according to a specific type of surgical instrument. SEM micrographs were also obtained on explants that failed in situ, and the morphology of the corresponding failure sites was examined. The study was designed to document a range of failure mechanisms associated with gel‐filled, saline‐filled, double‐lumen (saline‐gel), and soybean oil‐filled implants. The results of the study also demonstrate that SEM can often be used to determine the cause of breast‐implant failure. (Plast. Reconstr. Surg. 108: 52, 2001.)

Medical mineralogy as a new challenge to the geologist; silicates in human mammary tissue?

Abstract Medical questions surrounding the toxicity of “silica” and other silicon-containing materials introduced into the body can be answered only through use of microanalytical techniques that provide chemical and structural analyses of microscopic and submicroscopic particles. A useful approach to the study of minerals and other foreign substances associated with silicone breast implants is to use polarized-light optical microscopy to pinpoint the materials of interest in the tissue and to follow that observation with analysis by Raman spectroscopy. Silicone breast implants contain both the organic polymer silicone and particles of amorphous silica. We studied the breast tissue from six women who had silicone breast implants and from three controls who never had implants to address questions about post-implant alteration, such as to “crystalline SiO2.” Optical analysis of the mammary tissue sections revealed a variety of birefringent and non-birefringent, non-cellular materials. Raman spectroscopic analyses of those substances identified many similar materials in tissue from women with and without silicone implants: calcite, apatite, starch, lipid, and β-carotene. We also spectroscopically identified silicone (only in breast tissue from patients recognized to have had ruptured implants) and paraffin (only in one sample that had been embedded in paraffin and subsequently “deparaffinized”). In tissue sections of 5 μm thickness (standard thickness of pathology sections), it is impossible to detect optically the birefringence of quartz (or any other form of crystalline SiO2), even though it may be possible to image such thin crystalline SiO2 grains in polarized light due to light-scattering phenomena. Moreover, neither crystalline nor amorphous silica was identified by Raman spectroscopy in the tissue sections. Review of the pathology literature on such materialsbased issues as silicosis and calcification revealed some misapplication of the optical microscopy term “birefringence” and misleading identifications of minerals in tissue sections. Our conclusion is that useful collaborations can be developed between (1) pathologists who observe foreign materials in tissue sections and understand the medical context of their findings and (2) mineralogists who routinely use optical, chemical, and structural analyses to characterize micrometer-sized crystalline materials and who understand materials properties.

Analysis of Two Dow Corning Breast Implants Removed After 28 Years of Implantation

A pair of intact silicone gel breast implants that had been implanted for 28 years was analyzed after surgical removal in 1997 because of severe capsular contracture and heavily calcified capsules. The implants, manufactured by Dow Corning Corporation, were seamless, teardrop-shaped Cronin style (Silastic® 0) with Dacron® fixation patches. To determine the effects of long-term implantation, the material properties of tensile strength, elongation, tear resistance, 200% modulus, 400% modulus, and cross-link density were measured and found to be within the minimum-to-maximum range of properties for control implants of this type. This analysis indicates there was little or no large-scale material degradation of the elastomer shells after 28 years of implantation. Scanning electron microscopy examination of the shells was also performed and revealed that one implant wall had a defect caused by a scalpel cut accidentally induced at the time of explantation. The other explant had a very small area containing an unusual abrasion pattern of unknown origin. Otherwise, the surface structure of the 28-year-old explants showed no significant signs of wear, abrasion, or other indications of elastomer degradation. It may be true that breast implants are more likely to fail over time. However, our analysis of these implants indicates that these particular silicone shells showed no significant degradation after 28 years of implantation.

Initial Results From an Online Breast Augmentation Survey

BACKGROUND Data have been lacking to answer many questions raised in the clinical literature and by the US Food and Drug Administration with regard to patient satisfaction with breast implants, informed consent, the impact of augmentation on quality of life, repeat operations, and other issues related to breast augmentation. OBJECTIVE The authors conducted an online survey of women with and without breast implants to collect data on key issues related to breast augmentation. METHODS A survey including 177 questions was posted on the Web site www.implantinfo.com for 6 months, from August 2001 to February 2002. The survey was aimed at women who had undergone augmentation and those who were considering augmentation but had not yet undergone surgery. The raw data were analyzed by Data Harbor (Chicago, IL), an independent data management and technology development company with experience in managing large, complex medical databases. RESULTS The survey was completed by 4011 women, including 2273 who had received breast implants and 1738 who were considering augmentation. Among the key findings: More than half of the women who had undergone breast augmentation and those who were considering the procedure thought about the decision for at least 3 years before proceeding. Most women who underwent breast augmentation (88%) were satisfied with the results, and 93% said they would recommend the procedure to friends or family members. Nearly all women who received implants thought the surgery improved their overall appearance (92%) and self-confidence (82%) but said it did not result in significant changes in their marriage/dating activities, careers, or social lives. At least 92% said their surgeons had answered their questions and listened to their concerns, and more than 75% said they remembered being informed of the risks of surgery. The percentage of women with breast pain was greater among women with implants than among those without. However, other physical symptoms, such as those associated with rheumatologic diseases, were more common among women considering augmentation. Respondents with implants did not smoke at levels higher than comparable women in the general population and were not major consumers of alcohol. CONCLUSIONS The Online Breast Augmentation Survey provides a wealth of previously unavailable data on women who have undergone or who are considering breast augmentation. The data indicate that women consider breast augmentation carefully, that they are well informed by their physicians before surgery, and that they are generally happy with the results.

DMSO: Applications in Plastic Surgery

The authors point out that dimethyl sulfoxide (DMSO) increases tissue perfusion and may effectively treat or prevent ischemia in flaps. They recommend application of topical DMSO every 4 to 6 hours, until blood flow improves, to areas that show signs of ischemia or less than adequate perfusion. Other potential cosmetic surgery uses of DMSO include areas of skin care, pain relief, and treatment of keloids.

The Physics of Suction-Assisted Lipoplasty

BACKGROUND Some medical equipment manufacturers and surgeons have asserted that certain types of cannulas and other components of liposuction systems enhance the efficiency of fat aspiration. OBJECTIVE A laboratory experiment was designed to evaluate the effect of each component of a standard liposuction system on the rate of fat aspiration. A clinical investigation of the effectiveness of a vented (Turbo) cannula versus that of a standard cannula was also undertaken. METHODS The equipment used for the experiment included cannulas of varying lengths and diameters, provided with different tip geometries, suction tubes of 2 diameters, graduated canisters, and a vacuum pump. Applesauce was used as a simulated aspirant because its consistency appears similar to that of a mixture of fat and infiltrate. The time required to aspirate 1500 mL of material, with the pump set at maximum vacuum and the temperature and barometric pressure held constant, was measured. RESULTS Aspiration rates for the laboratory experiment with Becker, Keel Cobra Accelerator III, and Mercedes tip geometries were similar. In general, clinical aspiration rates were significantly lower than the laboratory rates. A higher aspiration rate was obtained with the vented Turbo cannula than with the conventional cannula. CONCLUSIONS Cannula-tip geometry has a minimal effect on the rate of aspiration; however, use of a tip less than 4 mm in diameter can cause clogging with fibrous tissue and significantly decrease the rate of aspiration. Aspiration is directly proportional to cannula and suction-tubing diameter and inversely proportional to cannula and suction-tubing length. Vented cannulas can enhance aspirate flow and efficiency. Further research is needed to investigate the significance of the fat fragmentation process and the development of fluids to simulate infiltrate/fat solutions in laboratory experiments.