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Transurethral thermotherapy of the prostate is a sixty minute, non-surgical, minimally invasive procedure that administers up to 60 watts of microwave energy to the central zone of the prostate as a treatment of symptoms of benign prostate hyperplasia (BPH). The microwave delivery system allows application of microwave energy to the central zone causing coagulation necrosis of the tissue while preserving the urethral lining with a circulating coolant. This procedure results in an improvement in urinary symptoms over time as this tissue is sloughed, resorbed, and retracted in size.
Thermotherapy was introduced in the United States in 1991 during FDA clinical trials and since approval has been an increasingly accepted alternative to the "gold standard" transurethral resection of the prostate (TURP). The concept of thermotherapy, along with other nonsurgical treatments such as interstitial laser therapy and transurethral needle ablation (TUNA), evolved in part due to the need for less invasive treatment for a condition with low morbidity and rare mortality. BPH may negatively affect a manís quality of life, which is often what causes him to seek treatment. However, it has a variable natural history. Progression occurs in less than a third of patients. The remaining patients have symptoms that either remain stable or actually improve over time without treatment (Roberts & Blute, in press). Complications such as urinary retention and renal insufficiency are relatively uncommon if left untreated (Kirby & McConnell, 1997). This lack of significant morbidity related to BPH has fueled the quest to find less invasive procedures than the TURP.
Transurethral thermotherapy is a single sixty minute session that can be performed in an office, clinic or mobile unit without intravenous sedation, or spinal or general anesthesia, thereby reducing complications and treatment costs. Clinical trials for thermotherapy have suggested this technology can provide a safe, well-tolerated, and effective treatment for symptoms of BPH (Blute, Patterson, Segura, Hellerstein & Tomera, 1994; Blute, Tomera, Hellerstein, McKiel, Lynch, Regan, & Sankey, 1993; Ramsey, Miller & Parsons, 1997; Larson, Blute, Bruskewitz, Mayer, Ugarte & Utz, 1998). Pain or discomfort management during thermotherapy, reported descriptively in these clinical trials, ranges from intraurethral lidocaine only to intravenous sedoanalgesia. Patient comfort management practices in the clinical setting continue to be disparate and dependent on the treatment environment.
The prostate gland consists of a central gland, peripheral gland and transition zone which is adjacent to the urethra and approximates the central gland. The transition zone is the area where BPH usually develops. The prostate grows under the influence of the testosterone metabolite, dihydrotestosterone. The metabolite stimulates growth factors and creates an imbalance with the simultaneous decreased production of transforming growth factor beta, which is responsible for apoptosis, or normal, programmed cell death. This process results in the stromal and epithelial hyperplasia seen in BPH (Kirby & McConnell, 1997). The hyperplasia is comprised of smooth muscle and connective tissue as well as glandular tissue. Stimulation of the alpha 1-adrenoceptors of the prostate smooth muscle cells by noradrenaline will result in an increase in prostate tone, which is also a component of BPH (Kirby et al., 1997). Transurethral thermotherapy is designed to reduce the volume or bulk of the transition zone of the prostate. It may also decrease the tone of the prostate by destroying alpha adrenoreceptors. This factor is important because the symptoms experienced by the patient may not always be directly correlated with an increase in prostate size. Both the tone and the bulk of the prostate can be responsible for urinary obstructive symptoms. Patients may present with urinary obstructive symptoms without any objective evidence of obstruction, or may have objective obstruction or benign prostate growth, but no symptoms (Roberts & Blute, in press).
Transurethral thermotherapy of the prostate is administered through a urethral catheter which embodies a helical microwave antenna, thermometry, and a lumen to allow continuous circulation of chilled sterile water around the antenna throughout the procedure. The principle mechanism of thermotherapy is the focus of adequate microwave energy to ablate the transition zone of the prostate without damaging the surrounding tissue of the urethral sphincter, bladder, rectum and urethra (Blute, 1996). The circulating coolant contributes to the maintenance of a urethral temperature in a safe temperature range, around 40° C. This temperature is well below 45° C., the threshold of human perception of pain and the point at which cell death occurs (Cleland & Gebhart, 1997). During thermotherapy, the central gland of the prostate is heated to a temperature of >45° C for approximately one hour, inducing cell death by coagulation necrosis (Larson, Bostwick & Corica, 1996). As an additional safety measure, rectal thermosensors employed during thermotherapy will cause microwave power shutdown in the presence of rectal temperatures above the preset threshold of 42.5° C. Larson, Collins & Corica (1998) found the preferential heating pattern of the dipolar antenna employed by one brand of thermotherapy device allows adequate interstitial temperatures of the prostate without significant changes in the rectal temperatures. In this study of interstitial temperature mapping of the prostate for 22 patients during thermotherapy, marked increases in intraprostatic temperatures as high as 80° C. were observed with very little elevation in the urethral or rectal temperatures (Larson et al., 1998).
Most complications of thermotherapy are transitory but include acute urinary retention, urinary tract infection, hematuria, dysuria, hematospermia, acute incontinence, rectal or urethral discomfort, and worsening of urinary symptoms. Patients can expect improved urination approximately four to six weeks after thermotherapy.
Although catheter design and temperature settings contribute to treatment tolerability, patients will voice complaints of discomfort such as a burning or stinging sensation at the tip of the penis, a sense of urgency, occasional bladder spasms, rectal fullness, or a vague, diffuse heaviness or pressure in the pelvic area. At times, patients will appear restless, but are unable to describe actual discomfort. These complaints usually begin within 15-20 minutes after the initiation of microwave power at 20 to 25 watts of microwave power, peak approximately 30 minutes into the therapy when the urethral temperature reaches 38.5 degrees C., and vanish when microwave power is terminated, without residual discomfort. Maximum discomfort as reported by the patient rarely endures for the entire therapy, but will occur early in therapy and last for 10-15 minutes. As the thermotherapy begins to actually cause tissue destruction, it is possible to reduce microwave power while maintaining an adequate or therapeutic temperature in the prostate of 55-80 degrees C. In most cases, the patient will find the treatment tolerable and will hesitate to actually label the sensation as "pain". On rare occasions, the treatment may need to be aborted for patient intolerance. Equally rare is the vasovagal reaction and associated bradycardia, which has occurred in response to discomfort in some patients. In all cases, the bradycardia resolved spontaneously as discomfort lessened.
The introduction of a nonsurgical procedure for BPH into the predominantly surgical setting of urology has raised questions and concerns regarding appropriate management of procedural pain and discomfort for a sixty minute procedure performed in the absence of anesthesia. Most centers treat in response to the patientís report of pain as well as through methods customary to the treatment setting. Though thermotherapy is administered by the urologist, the urology nurse plays a vital role in patient comfort management. The urology nurse is present throughout the procedure and is usually the person responsible for assessment and intervention for pain during thermotherapy. Pharmacological measures have included a range of medications, with intraurethral lidocaine gel used universally.
Pharmacological pain management during clinical trials was reported descriptively. Ramsey, Miller & Parsons (1997) reported 44% of their patients received intravenous sedation, 13% received an oral anxiolytic, 3% received an antispasmodic, and 25% received a nonsteroidal anti-inflammatory, either orally or intramuscularly. In the United States, 60% of patients received a nonsteroidal anti-inflammatory, 16% received an oral anxiolytic, and 35% received intravenous sedation or analgesia. An antispasmodic was used in 25% of patients (Larson, Blute, Bruskewitz, Mayer, Ugarte & Utz, 1998). The effectiveness of these pain measures was not reported. Durben Peterson, Hanson, Patterson, & Blute (1996) reported that for 34 patients, treated at Mayo Clinic during the United States IDE clinical trials of the Urologix T3 device with minimal pharmacological intervention (12 patients received an oral nonsteroidal anti-inflammatory), 21 % reported maximum discomfort was mild, 47 % moderate, and 32 % severe. No patient felt the pain was intolerable. In no cases was the patient discomfort treatment limiting. In most cases (74%), the maximum discomfort occurred early in treatment.
Two single blind randomized trials for pain management during thermotherapy have been reported. Cormio, Bloem, Laduc & DeBruyne (1994) randomized 83 patients to either a pre-emptive analgesic alone or in combination with an anxiolytic agent. Though the average pain score using the visual analogue scale was not statistically different between groups, when these scores were categorized into classes of good, fair and poor treatment tolerance, the differences between groups for good and fair tolerance was statistically significant. The authors concluded anxiety is the treatment-limiting factor in thermotherapy.
A second trial by Djavan, Shariat, Schafer & Marberger (1998) compared intravenous sedoanalgesia to intravenous saline in 45 patients during therapy and found no significant differences in peak visual analog scale scores between groups, measured at 2.0 and 2.2 respectively on a scale from 0-10. These authors concluded thermotherapy may be administered safely without intravenous sedoanalgesia, but did not speculate as to whether anxiety was a factor in treatment tolerance. All patients may have benefited by a reduced anxiety level due to the placebo effect of the intravenous method of administration, which may have then led to a decreased pain perception.
Differences between pain assessment and management across clinical settings may be due to patient comfort measures implemented by some centers to reduce patient anxiety. The range of treatment settings from small office examination rooms to hospital suites will, itself, impact the comfort management. Management of anxiety is very likely a major component of pain management during thermotherapy. Briggs (1995) reported that anxiety is a complex concept that is divided into two categories, anxiety state and anxiety trait. It is the anxiety state that can be affected prior to procedures with teaching and support measures. Volcier (1975) found four factors that correlated to increased pain during hospital procedures. These factors were loss of independence, lack of information, threat of severe illness, and problems with medication. Durben Peterson, Hanson, Patterson, & Blute (1996) reported the use of informal distraction and relaxation techniques such as music, conversation, reading material and the presence of a significant other during the procedure as effective patient management techniques which may have allowed them to perform all treatments with very little pharmacological intervention. Distraction techniques that require light patient concentration, such as a short video, are often effective. One center uses a comfortable recliner, which provides back support and less restricted leg movements. In this position, the patient may feel less vulnerable and more involved in his treatment, also improving tolerability. Physical comfort measures include a cool cloth on the patientís forehead, sips of water, dimming of lights, and cushioning of the knees during therapy. Thorough patient education, through face to face interaction with the urologist and urology nurses, and review of treatment brochures and videotapes, has been reported as a method of relieving anxiety (Durben Peterson et al., 1996). Patient teaching is most effective when performed at an appropriate level of comprehension. Anxiety levels are affected by the patientís perception of caregiver confidence in the performance of this procedure. The treatment setting alone can be anxiety producing and patients may be more comfortable and relaxed in a quiet office than they would have been in a brightly lit, sterile, bustling hospital environment (Durben Peterson et al., 1996). Manipulation of the environment to induce calm is often very effective as stress reduction in other physically distressing events such as childbirth. The effect of comfort measures afforded by nursing personnel during this therapy cannot be overlooked and warrants further investigation as to whether these measures can truly manage a patientís anxiety and pain perception during treatment with or without adjuvant pharmacologic management.
Thermotherapy has emerged as a promising treatment alternative for benign prostate
hyperplasia for which continued investigation into appropriate pain management is
imperative. Patients who are active, generally healthy and very involved in their
health care will seek minimally invasive treatments like thermotherapy, with few
complications and no post treatment restrictions. Patients seeking alternative treatment
are often very well informed and have expectations beyond past generations in wanting
health care that can be administered without medication. Administration of this treatment
in an anesthesia free environment will sometimes pose the situation where the typical
pain management used is inadequate for a particular patient. It is difficult to identify
these patients prior to treatment to institute more aggressive pre-emptive pharmacological
management. For some of these patients, treatment may need to be aborted. Yet, the
problem of the significant variability in pain management for most patients may be
reduced by establishing standard recommendations for this procedure, which can be
identified through further clinical research of pain management. Future studies should
identify both pharmacological and nonpharmacologic measures that are effective in
reducing pain and anxiety during treatment. Continued experience with this technology
by growing numbers of urology personnel will also contribute to the body of knowledge
regarding importance of implementing comfort measures as well as pharmacological
measures for this therapy.
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Manuscript submitted for publication.
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