ANATOMY OF VASCULAR LESIONS
The vascular concerns that the dermatology nurse or nurse practitioner are most likely to see range considerably in size and construct. Each class of lesion varies in the diameter, configuration, and density of vessels involved. Location and severity also varies from patient to patient, and all of these factors must be included in the treatment assessment. The following is a summary of lesions commonly considered amenable to treatment with a vascular laser, either solely or in combination with medical treatment, the latter of which is beyond the scope of this article.
Rosacea
Rosacea is a common and challenging condition to treat as it is dynamic and progressive. Different classification systems have been used to categorize the multifactorial presentation of this complex condition. The discussion of vascular laser treatment is most relevant to the most predominant subtype, erythematotelangiectatic rosacea. Characterized by episodes of facial flushing, it involves primarily the central face-cheeks, nose, chin, and to a lesser extent, forehead. Triggers may include heat, temperature changes, alcohol, stress, strong emotion, and spicy foods (Crawford, Pelle, & James, 2004). Over time, select vessels become permanently dilated so the individual has a persistent "ruddy" complexion. Patients present with a spectrum of vessel sizes-from small vessels that coalesce to create a generalized pinkness to large telangiectasias that are visible to the naked eye. At its worst, the condition presents as a flagrant network of visible blood vessels in some or all areas of the central face on a background of erythema. Some patients note an unpleasant burning or tingling sensation during a flare.
It is important to inform patients that laser therapy has no impact on the underlying and still not fully understood mechanism of flushing. Laser therapy is meant to reduce redness and visible vessels. The physical destruction of vessels not only improves appearance but also can improve symptoms to the extent that it lessens the number of vessels dilating in response to flushing triggers. This provides only temporary relief of the condition, however, and over a period of years, patients will likely require maintenance treatment. For many patients with the condition, the prospect of any type of treatment that will minimize their facial redness is worth pursuing (Figure 1).
Spider Nevi
These are focal clusters of dilated vessels that radiate outward from a central, larger arteriole. They generally appear on the face, neck, and sometimes, the chest. Their presence may be associated with cirrhosis, especially alcoholic cirrhosis, or excessive estrogen levels but also occurs in approximately 15% of patients, including children, who have no underlying health issues. Although harmless, their red color and solitary presence on the face make them a conspicuous cosmetic annoyance to many patients (Goldsmith, Katz, Gilchrest, Leffell, & Wolff, 2012).
Venous Lakes
These small, elevated lesions with a dark-purple, almost blue color are found predominantly on the lips and, sometimes, the ears or face of older adults (see Figure 2). They are composed of dilated veins, either singularly or in a cluster of such vessels, that appear as one papule on gross examination (Kelly & Baker, 2012).
Port Wine Stains (PWS)
Also known as nevus flammeus, PWS are congenital capillary malformations that occur in approximately 0.3% of all newborn infants (Jasim & Handley, 2007). They come in virtually all shapes, sizes, and densities. They can occur anywhere on the body but are most common on the head and neck, where they are of particular cosmetic concern to parents and the socially aware patient. These pink to dark-red macules consist of a dense network of dilated capillaries in the superficial papillary and upper reticular dermis (Figure 3). If not treated, the involved skin can become thickened and even form nodules (Wall, 2007).
Cherry Angiomas
Cherry angiomas are round papules that may grow to several millimeters in size and are predominantly found on the trunk and extremities with increasing age. They are benign and generally asymptomatic, although larger ones may bleed with trauma (North & Kincannon, 2012).
Other Lesions With Vascular Involvement
Lasers may play an adjunct role in many other conditions that have a vascular component such as keratosis pilaris rubra, poikiloderma of Civatte, acne scars, striae, and surgical scars. These presentations all have unique textural issues that may be addressed by methods beyond the scope of this article. However, to the extent that laser treatment can reduce the conspicuous redness of these conditions, it is invaluable.
BASIC LASER CONCEPTS
Familiarity with the above lesions is essential for the nurse practitioner ordering treatment and for the nurse following prescribed parameters. This becomes evident after a review of the basic technical components of laser mechanics.
The cornerstone concept of vascular laser technology is that of "selective photothermolysis," which Kim, Roher, and Geronemus (2005) succinctly define as "the ability to target a specific chromophore in the skin without damaging surrounding structures through the selection of proper wavelength, pulse duration and fluence" (p. 11).
Oxyhemoglobin is the operative chromophore in all vascular lesions (Kim et al., 2005). Science has shown that hemoglobin preferentially absorbs light energy to a maximum degree at the wavelengths, in nanometers (nm), of 418, 542, and 577 nm and has a smaller peak between 700 and 1100 nm. Lasers relevant to vascular treatments are designed to emit wavelengths within the range of these peaks. When hemoglobin absorbs light energy, the resulting heat is transmitted to the encasing vessel, causing intravascular coagulation and contraction of collagen (Wall, 2007). Macrophages gradually dispose of the nonviable tissue so the vessels no longer fill with blood.
As light waves pass through the skin, some are scattered in various directions as they encounter different skin molecules, thus lessening the energy delivered to the target. Longer wavelengths scatter less and therefore penetrate deeper into the skin compared with shorter wavelengths (Barlow & Hruza, 2005).
If hemoglobin were the only chromophore in the skin, vascular treatments would certainly be more straightforward. However, water and melanin molecules also act as light absorbers. Ross and Paithankar aptly describe the melanin-dense epidermis as the "innocent bystander" of laser treatments intended for deeper vascular lesions (p. 128). As the laser light passes through the skin, absorption by melanin can cause the unwanted side effect of hyperpigmentation and surface injury, especially with shorter wavelengths. Current lasers contain integrated cooling systems that coordinate with the laser pulse to minimize epidermal damage without impeding the laser itself (Ross & Paithankar, 2005). Still, patients with dark skin types and especially those with tendency toward hyperpigmentation should be treated conservatively and cautiously.
Types of Lasers
There are several types of lasers that play a role in treating vascular lesions, and the laser technician would benefit from being familiar with the basic properties of each. Perhaps, the most pertinent is the flashlamp-pumped pulsed dye laser (PDL), which emits wavelengths of 585 or 595 nm depending on the manufacturer (Kim et al., 2005). These have been purposely developed based on the principle of selective photothermolysis to optimize treatment of vascular lesions.
Another technology is the neodymium:yttrium-aluminum-garnet laser, which emits a wavelength of 1064 nm and can be manipulated to halve the wavelength to 532 nm. Both wavelengths correspond to hemoglobin absorption peaks mentioned (Kim et al., 2005). Although the 1064 nm is less absorptive than those emitted by the PDL, the enhanced depth of penetration can play a role in treating deeper, recalcitrant vessels that may comprise a component of many common presentations such as PWS, telangiectasias, and hemangiomas. Similarly, the alexandrite laser, which emits light at 755 nm, is not the first choice for most vascular lesions because hemoglobin suboptimally absorbs light at this wavelength. However, it may play a role for deeper vessels that are better reached by this relatively long wavelength (Srinivas & Kumaresan, 2011; Wall, 2007).
Finally, intense pulsed light (IPL), which is technically not a laser, can be an important tool in treating vascular lesions. IPL functions per the principles of selective photothermolysis, but in a less precise way. Rather than emitting a solitary wavelength, IPL systems produce a spectrum of wavelengths from 500 to 1200 nm and come with a series of filters to manipulate exposure of wavelengths based on skin type and lesion characteristics (Srinivas & Kumaresan, 2011). Unlike laser systems, the IPL delivery device is placed directly onto the skin. The author's experience is primarily with the 595-nm PDL and the IPL system, and these will therefore be the focus of this article.
Laser Variables
Given a fixed wavelength (or spectrum of wavelengths in the case of IPL), there is a set of three parameters that the laser technician can manipulate to tailor treatment to a particular lesion. Fluence is the level of energy unleashed onto the skin and is measured in joules per square centimeters (J/cm2); the pulse width is the time in which a given fluence is delivered and is measured in milliseconds (ms). Finally, the spot size refers to the diameter of the circular delivery aperture and is measured in millimeters (mm). Smaller spot sizes tend to cause more scatter of light and therefore deliver less energy compared with larger spot sizes (Srinivas & Kumaresan, 2011).
Once heated to a maximum level, a vessel will cool as heat dissipates to the surrounding tissues. The time it takes to lose approximately 50% of that peak temperature is called the thermal relaxation time (TRT; Bencini, Tourlaki, De Giorgi, & Galimberti, 2012). TRT is a function of vessel diameter, such that the larger the vessel, the longer the TRT. Theoretically, optimal vessel damage occurs when the pulse width is about equal to the TRT: Any longer and excess heat will incur damage to nearby structures; any less and the vessel itself will not receive enough heat to induce the desired end point of coagulation (Kim et al., 2005). Comparable to boiling a cup of water versus a full bathtub, at a fixed output of heat (analogous to fluence), the former will take much less time before it releases heat energy into the surrounds in the form of steam; the larger volume will require much more.
Thus, when determining what treatment parameters to use, the first step is to consider the anatomy of the lesion and the average size of the vessel structures involved. This will help determine the appropriate pulse width to use. Likewise, optimal fluence levels correlate to the size of the vessel to be treated. The parameters typically used to treat venous lakes (Figure 2) and PWS (Figure 3) exemplify this concept. The PWS, composed of many fine vessels with small diameters, would best be treated with a 595-nm PDL system at relatively short pulse widths of 1.5 or even 0.45 ms (other levels are 3, 6, 10, 20, and 40 ms). The pictured lesion is relatively light and required three treatments. A darker, denser lesion would require several more, depending on the patient's goals.
At the other end of the spectrum is the venous lake, which was treated with a comparatively long pulse width of 20 ms, a spot size of 10 mm, and a fluence of 15 J/cm2. This significantly reduced the lesion, but a second treatment at 10 ms, 10-mm spot, and 15 J/cm2 was required to achieve complete clearance.
The same general principle applies to the IPL system, although the figures are on a different scale. Illustrating this is the patient with rosacea in Figure 1. In this case, the visible telangiectasias were treated with a 560-nm filter, a relatively long pulse width of 20 ms, and a fluence of 25 J/cm2. In contrast, the fine vessels comprising the underlying erythema were treated with the same filter at a shorter pulse width of 10 ms and lesser fluence of 16 J/cm2.
Clinical Application
Familiarity with the anatomy of vascular lesions and technical understanding of laser/tissue interaction are basic requirements to treat the vascular patient. They are the building blocks on which the laser nurse adds assessment of intratreatment response to finesse treatment parameters according to the goals that have been established between the patient and the practitioner.
Fortunately, response to treatment is easily assessed as it is immediate and visually apparent. Depending on the parameters used, skin response with the PDL laser will fall somewhere along a spectrum: from no response or slight pinkness at one end, increasingly intense erythema in the middle and dark purpura at the extreme. Shorter pulse widths tend to cause purpura, and indeed, this is the optimal end point for effective treatment of PWS with PDL. This will be seen as a deep purple mark immediately after a pulse.
For other conditions with fine erythema, such as the erythema of rosacea or keratosis pilaris rubra, treatment at a purpuric level is also ideal. However, it may take 10 days to 2 weeks for purpuric discoloration to clear, and most patients cannot afford the downtime socially and/or professionally. In these cases, improvement can still be achieved at subpurpuric levels but with more treatments. Clinically, the subpurpuric threshold can be appreciated immediately after delivering a pulse as an almost-imperceptible dusky gray color in the shape of the circular spot aperture. The grayish color can be fleeting or last a few seconds before the skin flushes with erythema. This subpurpuric level is generally achieved with pulse widths in the middle range, depending on the fluence.
For telangiectasias, coagulation of the vessels is marked by an instantaneous change from red to a gray/black outline. Smaller vessels may be seen as a gray/purple outline before disappearing into a background of erythema. Larger vessels will turn dark purple upon coagulation and remain so for varying lengths of time measured in seconds. If they are seen to revascularize quickly, the fluence is probably too low. Ideally, the vessel will remain purple for 10 seconds or more. The longer the intravascular coagulation time, the better chance of permanent removal. Similarly, venous lakes and cherry angiomas should remain purple if treated effectively (Figure 4). If telangiectasias do not appear to coagulate with a given fluence, the operator may either increase the fluence or employ the technique of "pulse stacking." By delivering two pulses in rapid succession, the vessels are first damaged and then coagulated by the additive heat from the second pulse.
The novice laser operator will want to review the manufacturer's treatment guidelines and titrate up from conservative doses until experience allows for more fluent decision making. Taking the time to do test spots using a series of pulse widths and fluences is an invaluable investment for the new operator and certainly for the trusting patient. (Candela Corporation, 2005).
Patient Preparation
Proper assessment of the lesion and a firm grasp of appropriate treatment parameters are not only essential from a clinical perspective but also for reassuring the patient before embarking on what is often an emotional and anxiety-provoking process. The practitioner's authoritative explanation of the procedure, in terms appropriate to the patient's level of understanding, is foremost in instilling confidence.
Many patients are justifiably curious as to how the technology works. A simple analogy of a bucket filled with rocks and sponges and covered with fine netting may be used to help patients relate to the process. Water poured into the bucket will pass easily through the net without tearing. Similarly, laser light passes through the stratum corneum, treating the target vessels without rupturing the skin. Most patients intuitively understand that, because of their natural properties, the sponge will absorb the water, whereas the rocks will not. Such is the behavior of light, which is absorbed by the blood in the vessels while the surrounding skin remains unaffected. Patients are often put at ease by the fact that they will not have open sores; female patients are also happy to know that they can therefore apply makeup soon after the treatment to conceal the aftereffects.
Informed consent, including possible risks, side effects, expected outcomes, the expected course of healing, and projected course of treatment should all be reviewed. Small, superficial lesions like the spider nevus (Figure 5) or cherry angiomas may clear with one treatment, but most conditions involving diffuse erythema will realistically require two to three sessions for adequate suppression. PWS can take eight or more sessions to lighten, and full clearance is often not possible. Treatments are typically repeated 4-6 weeks apart.
Side Effects
In the case of vascular laser treatment, many side effects such as swelling, erythema, and various degrees of purpura are in fact inherent to the goal of inducing tissue damage. The patient should be made fully aware of these anticipated outcomes as well as the rare but possible unwanted side effects of infection, scarring, hyperpigmentation, or hypopigmentation. These complications are very rare with the advent of PDL lasers, whose target selectivity and surface cooling system allow for much more refined vascular treatment than in the past (Tanzi, Lupton, & Alster, 2003).
Safety
Obviously, the safety of the patient and operator is of utmost importance. Anyone operating a laser should complete a certified laser safety course. For the purposes of this article, the fundamental precaution deserving mention is that of eye safety. Laser light can be potentially damaging to eye structures. It is essential that patients' eyes are covered and that the operator have eyewear that protects against the specific wavelengths emitted by the machine being used (Candela Corporation, 2005).
Pain
The issue of intraprocedural pain is of enough concern to warrant extra discussion. "Does it hurt?" is perhaps the most common question patients ask during the consultation process. Laser therapy involves intense heat energy delivered in a concentrated time frame-discomfort is to be expected. Each patient's perception, emotional state, and pain threshold will vary considerably. The laser pulse is often described as a "rubber band snapping," but many patients might argue this is a gross understatement, especially given that a treatment session can require up to several hundred pulses. The sensation of a laser pulse is unique unto itself; patients are not likely to have had any similar experience to which they can refer as mental preparation. The combined prospect of exposing oneself to an unfamiliar and painful sensation while vulnerably blindfolded with eye shields can create a great deal of anticipatory anxiety.
The effective laser nurse will prepare the patient for the prospect of discomfort with empathy and reassurance (see Table 1) as well as a repertoire of options for pain control. On this subject, the literature seems notably sparse. Research to date has primarily focused on laser mechanics and little on the patient experience. The ideal analgesia should be effective, be easy to administer, and have no or very mild potential side effects. Cold air is one such modality and should be considered a basic component of any laser program. Patients can hold the nozzle and direct it where needed during the procedure. The cool air counteracts some of the painful heat sensation while giving the patient a distraction and sense of control.
Pharmacological options include topical agents, anxiolytics, and oral analgesics (Kilmer, 2005). Topical lidocaine, prilocaine, and tetracaine in different concentrations and bases are available for use before treatment. Presumably, oral analgesics would play a role in prophylactic analgesia, but there are no controlled studies comparing different agents or the effectiveness of individual agents at various fluence thresholds. As lasers become more widely available and their use becomes more common, this should be an area of more study in an effort to improve the patient experience.
Anecdotally, the clinic of this author has had some success using the inhaled analgesic methoxyflurane (Penthrox) for patients who are either highly anxious and/or find vascular laser treatments prohibitively painful. It is indicated for pain relief in conscious, hemodynamically stable patients, and although it can cause drowsiness, patients are able to self-administer the vapor via a handheld device while undergoing the laser treatment. The device comes with 3 mL of drug, which provides enough analgesia for the average treatment session. It has a quick onset of about 10 inhalations, and the effects begin to wear off within minutes of ceasing to inhale the drug. The major contraindications relevant to the outpatient population are renal or liver impairment/failure, hypersensitivity to the drug, and malignant hyperthermia (Medical Developments International, 2012).
Conclusions
Successful treatment of vascular lesions requires a firm grasp of the technical concepts coupled with attentive clinical assessment before, during, and after therapy. Whether prescribing treatment parameters or applying the parameters set by a supervisor, the laser nurse has a responsibility to his or her patients to understand the rationale behind dosing levels. This understanding increases the operator's confidence, enhances communication between supervisors and operators, and allows the laser professional to accurately answer the inevitable patient questions about how laser technology can treat vascular lesions. As knowledge and experience deepen, the laser nurse can look forward to a great sense of satisfaction from helping patients resolve their cosmetic concerns.
REFERENCES