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PubMed1995

Gold-tip laser sleeve for a bare fiber.

A gold-tip laser sleeve for a bare laser fiber has been used for Nd:YAG laser irradiation of the prostate in both the canine model and a pilot clinical series. In the animal model, irradiation was undertaken using the Ablaser catheter through an open suprapubic cystotomy, and the procedure was monitored by video endoscopy via a perineal urethrostomy. Intraprostatic heating profiles were determined using real-time interstitial thermometry. As long as no carbonization occurred, irradiation with higher wattage resulted in higher intraprostatic temperatures. The "popcorn effect" caused a superficial temperature reduction but did not alter the ability of thermal conduction to heat deeper in the prostate. A small series of patients has been treated, with good results.

Aged↗
PubMed1997

Thermal ablation of canine prostate using interstitial temperature self-regulating seeds: new treatment for prostate cancer.

An interstitial temperature self-regulating implantable thermal seed for ablation of the prostate was investigated for the treatment of cancer. The technique is analogous to brachytherapy implants with three important advantages: highly localized temperatures may reduce complications, the thermal seed can be activated for retreatment at any point in time, and the seeds pose no radiation hazard to the clinical staff. Thermal seeds were implanted in the left lobe of the prostates in four dogs; the right lobe was a control to evaluate undesired heating outside the seed array. Linear-array thermometry probes were placed in both lobes, and the induction field for heating the implants was activated for 1 hour. After treatment, biopsies were taken from both lobes at 4-hour intervals up to 28 hours to evaluate thermal damage and thermotolerance as measured by expression of heat shock protein (hsp) 70. Only 5 minutes was required to heat the left lobe to 45 degrees to 55 degrees C. The maximum and minimum cumulative equivalent minutes at 43 degrees C (CEM43) thermal doses in the treated lobe were 174 and 4.4 hours, respectively; less than a 1-minute CEM43 was observed in the control lobe. Elevated hsp70 expression was detected in tissue of the treated lobe between 12 and 24 hours after treatment; minimal increases occurred in the control lobe. The thermal seed system was effective at heating the prostatic volume without damage to normal tissues outside the implant array, and subsequent treatments were simplified in comparison with other hyperthermia devices. Expression of hsp70 implies that retreatment of the prostate at intervals as short as 48 to 72 hours may avoid thermotolerance making weekly treatment an appropriate regimen.

Animals↗
PubMed2000

Relation between intraprostatic temperature and clinical outcome in microwave thermotherapy.

PURPOSE: The study was designed to explore the relation between prostatic temperature and the clinical outcome of transurethral microwave thermotherapy (TUMT). PATIENTS AND METHODS: Forty-nine patients with symptomatic benign prostatic hyperplasia (BPH) were treated. Baseline evaluation included Madsen score, flowmetry, and pressure-flow study. Two fiberoptic thermosensors were placed in the prostate targeted to the region 10 and 20 mm below the bladder neck and 5 to 15 mm lateral to the prostatic urethra. The TUMT was carried out using either the low-energy (2.0) or high-energy (2.5) Prostasoft program. Follow-up was at 6, 12, and 26 weeks. RESULTS: A moderate correlation between intraprostatic temperatures and energy output (r = 0.409; P < or = 0.046) and prostate volume (r = 0.303; P < or = 0.0424) was observed. Outlet obstruction was associated with higher temperatures (obstructed 49.6+/-5.8 v unobstructed 46.1+/-4.2 degrees C; P < or = 0.033). A significant relation between temperature and clinical outcome was found. Patients with intraprostatic temperatures <46 degrees, 46-50 degrees, and < or = 50 degrees C had significant differences in Madsen score change (-50%, -68% and -86%) and in maximum flow rate (+26%, +32%, and +48%). Patients with temperatures >50 degrees C had a significant improvement in obstruction status (86% to 18%). A slight worsening in voiding dynamics was observed in patients with temperatures <50 degrees C. CONCLUSION: A significant relation exists between intraprostatic temperatures achieved during TUMT and the clinical outcome. Temperatures in excess of 50 degrees C seem to be associated with a greater improvement in lower urinary tract symptoms and bladder outlet obstruction. These data provide a sound rationale for monitoring intraprostatic temperatures and developing invasive thermometry feedback mechanisms for thermal treatments of BPH.

Aged↗
PubMed2002

Heating the patient: a promising approach?

There is a clear rationale for using hyperthermia in cancer treatment. Treatment at temperatures between 40 and 44 degrees C is cytotoxic for cells in an environment with a low pO(2) and low pH, conditions that are found specifically within tumour tissue, due to insufficient blood perfusion. Under such conditions radiotherapy is less effective, and systemically applied cytotoxic agents will reach such areas in lower concentrations than in well perfused areas. Therefore, the addition of hyperthermia to radiotherapy or chemotherapy will result in at least an additive effect. Furthermore, the effects of both radiotherapy and many drugs are enhanced at an increased temperature. Hyperthermia can be applied by several methods: local hyperthermia by external or internal energy sources, regional hyperthermia by perfusion of organs or limbs, or by irrigation of body cavities, and whole body hyperthermia. The use of hyperthermia alone has resulted in complete overall response rates of 13%. The clinical value of hyperthermia in addition to other treatment modalities has been shown in randomised trials. Significant improvement in clinical outcome has been demonstrated for tumours of the head and neck, breast, brain, bladder, cervix, rectum, lung, oesophagus, vulva and vagina, and also for melanoma. Additional hyperthermia resulted in remarkably higher (complete) response rates, accompanied by improved local tumour control rates, better palliative effects and/or better overall survival rates. Generally, when combined with radiotherapy, no increase in radiation toxicity could be demonstrated. Whether toxicity from chemotherapy is enhanced depends on sequence of the two modalities, and on which tissues are heated. Toxicity from hyperthermia cannot always be avoided, but is usually of limited clinical relevance. Recent developments include improvements in heating techniques and thermometry, development of hyperthermia treatment planning models, studies on heat shock proteins and an effect on anti-cancer immune responses, drug targeting to tumours, bone marrow purging, combination with drugs targeting tumour vasculature, and the role of hyperthermia in gene therapy. The clinical results achieved to date have confirmed the expectations raised by results from experimental studies. These findings justify using hyperthermia as part of standard treatment in tumour sites for which its efficacy has been proven and, furthermore, to initiate new studies with other tumours. Hyperthermia is certainly a promising approach and deserves more attention than it has received until now.

Antineoplastic Agents↗
PubMed2001

Vascular abnormalities in reflex sympathetic dystrophy (CRPS I): mechanisms and diagnostic value.

Complex regional pain syndrome type I (CRPS I, formerly known as reflex sympathetic dystrophy) is a painful neuropathic disorder that develops after trauma affecting the limbs without overt nerve injury. Clinical features are spontaneous pain, hyperalgesia, impairment of motor function, swelling, changes in sweating, and vascular abnormalities. In this study, the pathophysiological mechanisms of vascular abnormalities were investigated. Furthermore, the incidence, sensitivity and specificity of side differences in skin temperature were defined in order to distinguish patients with definite CRPS I from patients with extremity pain of other origin. In 25 CRPS I patients and two control groups (20 healthy subjects and 15 patients with other types of extremity pain), cutaneous sympathetic vasoconstrictor activity was altered tonically by the use of controlled thermoregulation. Whole-body temperature changes were induced with a thermal suit in which cold or hot water circulated. The vascular reflex response (skin blood flow, laser Doppler flowmetry, skin temperature, infrared thermometry) was analysed to quantify sympathetic outflow. Measurements were performed during a complete thermoregulatory cycle, i.e. during the entire spectrum of sympathetic vasoconstrictor activity from high (whole-body cooling) to low sympathetic activity (whole-body warming). Venous noradrenalin levels were determined bilaterally in five CRPS patients. (i) Three distinct vascular regulation patterns were identified related to the duration of the disorder. In the "warm" (acute) type of regulation, the affected limb was warmer and perfusion values were higher than in the contralateral limb during the entire spectrum of sympathetic activity. In the "intermediate" type of regulation the limb was either warmer or colder. In the "cold" (chronic) type of regulation, skin temperature and perfusion values were lower on the affected side during the entire spectrum of sympathetic vasoconstrictor activity. (ii) Noradrenalin levels were lower on the affected side, even in chronic patients with considerable cutaneous vasoconstriction. (iii) Temperature and blood flow differences between the two sides were dynamic and most prominent at a high to medium level of vasoconstrictor activity. (iv) In both control groups, there were only minor side differences in flow and temperature. In conclusion, it is suggested that, in CRPS I, unilateral inhibition of sympathetic vasoconstrictor neurones leads to a warmer affected limb in the acute stage. Secondary changes in neurovascular transmission may lead to vasoconstriction and cold skin in chronic CRPS I, whereas sympathetic activity is still depressed. Vascular abnormalities are dynamic. The maximal skin temperature difference that occurs during the thermoregulatory cycle distinguishes CRPS I from other extremity pain syndromes with high sensitivity and specificity.

Adult↗
PubMed2004

Irrigation scheduling: advantages and pitfalls of plant-based methods.

This paper reviews the various methods available for irrigation scheduling, contrasting traditional water-balance and soil moisture-based approaches with those based on sensing of the plant response to water deficits. The main plant-based methods for irrigation scheduling, including those based on direct or indirect measurement of plant water status and those based on plant physiological responses to drought, are outlined and evaluated. Specific plant-based methods include the use of dendrometry, fruit gauges, and other tissue water content sensors, while measurements of growth, sap flow, and stomatal conductance are also outlined. Recent advances, especially in the use of infrared thermometry and thermography for the study of stomatal conductance changes, are highlighted. The relative suitabilities of different approaches for specific crop and climatic situations are discussed, with the aim of indicating the strengths and weaknesses of different approaches, and highlighting their suitability over different spatial and temporal scales. The potential of soil- and plant-based systems for automated irrigation control using various scheduling techniques is also discussed.

Agriculture↗
PubMed1990

Initial results of phase I/II interstitial thermoradiotherapy for primary advanced and local recurrent tumors.

Since January 1986 in a phase I/II study, 45 lesions (30 head and neck, 11 pelvic, and 4 other lesions) in 44 patients (24 men, 20 women; age 18-81 years) received a combination of interstitial Ir-192 radiotherapy (IRT) and interstitial 915 MHz MW hyperthermia (IHT) supplemented by external radiation (ERT). In June 1989, evaluation was performed for lesions with minimum follow-up (FU) of 6 months and FU periods between 6 and 39 months (mean: 16 months, SD +/- 9). The tumors comprised 21 advanced primary (AP) lesions without prior ERT, 18 local recurrent (LR) and 6 local metastatic (LM) lesions with variable prior treatment modes; 24 lesions had received prior ERT between 40 and 70 Gy, 23 chemotherapy and 30 prior surgery. The mean dimensions of 42 lesions were 4.5 X 4.0 X 3.0 (cm3) with tumor volumes ranging from 12 to 135 cm3 (mean: 54 cm3, SD +/- 35); 3 lesions had extensive tumor volumes greater than 225 cm3. IHT was applied immediately prior to and/or after low-dose Ir-192 IRT (20-30 Gy) for 60 min at temperatures between 41 and 44 degrees C. ERT (40-50 Gy) was always given for AP and LM lesions, but variably applied for previously irradiated LR lesions, thereby avoiding the cumulative radiation dose exceeding 110 Gy per site. IRT doses ranged from 17-48 Gy (mean: 26.8 Gy, SD +/- 8) at a dose rate of 25-70 cGy/h (mean: 42 cGy/h, SD +/- 12). Thirty-three lesions received additional ERT of 30-56 Gy (mean: 46.5 Gy, SD +/- 9). Total radiation dose (IRT + ERT dose) ranged from 31 to 82 Gy (mean: 61 Gy, SD +/- 18). The hyperthermia systems of Lund/Buchler 4010 and Clini-Therm Mark VI/IX with thermistor or fiber-optic thermometry devices were employed. Initial response at 3 months FU showed 31 (69%) lesions complete response (CR), 10 (22%) partial response (PR), and 4 (9%) no change (NC). Long-term response of 30 lesions at 12 months FU revealed a total of 27 (90%) with local control (LC) and 3 (10%) in-field recurrences. Six patients died prior to 12 months FU, three with LC and three with progressive disease. So far 10 (22%) patients have developed distant metastases. Acute side-effects occurred in 15 lesions (33%) resulting in 12 (27%) long-term complications with 3 lesions (7%) requiring surgery.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Randomized phase III study comparing irradiation and hyperthermia with irradiation alone in superficial measurable tumors. Final report by the Radiation Therapy Oncology Group.

A total of 307 patients with superficial measurable tumors were registered on a Radiation Therapy Oncology Group (RTOG) protocol involving fractionated radiation therapy, either alone or followed immediately by hyperthermia (42.5 degrees C, 45-60 min). Overall complete response (CR) was observed in 30% of the lesions treated with radiotherapy (RT) and 32% of those receiving RT and heat. Response was found to be significantly related to both maximum tumor diameter (less than 3 or greater than or equal to 3 cm) and site/histology (breast/adenocarcinoma, head and neck/squamous, or other site/histologies). In tumors less than 3 cm in diameter in the breast, trunk, and extremities, a better CR rate was noted with irradiation and heat (62 and 67%) than with irradiation alone (40 and 0%). However, in the head and neck there was only minimal difference in CR with irradiation alone or combined with hyperthermia (50 vs 38%). In lesions less than 3 cm treated with irradiation and heat, there was improved local control. In lesions greater than 3 cm, there was no difference in local control between the two treatment arms. The higher response rate in patients with smaller lesions (less than 3 cm) may be explained by the fact that these tumors are easier to heat. Problems in correlating tumor response with quality of heating include less than optimal heating in larger lesions and the limited ability of current thermometry to map the temperature distribution in a tumor. Acute and late toxicities in both treatment arms were comparable, except for an overall 30% incidence of thermal blisters in the heated tumors.

Adenocarcinoma↗
PubMed1995

Thermoradiotherapy for brain tumors. Three cases of recurrent malignant astrocytoma and review of clinical experience.

Three patients with symptomatic, recurrent supratentorial malignant astrocytoma were retreated with combined interstitial iridium-192 brachytherapy (RT) and hyperthermia (HT): 50 Gy at 50 cGy/h was delivered 10 mm outside the computed tomography (CT) enhancement border through stereotactically placed plastic tubes, and 915-MHz microwave antenna heating was done for 60 min within 30 min either before or after irradiation. Invasive thermometry data were obtained from the tumor and adjacent brain tissue. The patients tolerated the treatment well and two thirds improved. All patients developed cerebral edema, one also developed scalp infection, and another patient developed meningeal infection. Exceeding the expectancy without treatment, overall survival was 7, 12, and 15 months. On autopsy, two of the patients' brains revealed no active tumor in the treated regions, but one displayed tumor in untreated parts. The HT-RT treatment was very effective, but the original tumor extent was not apparent by the CT imaging technique. A postimplant resection approach may be advisable to minimize postimplant edema. Our data are in agreement with the available literature on more than 400 patients. However, our aim of extending survival decisively could not be realized.

Adult↗
PubMed1997

Influence of thermoregulatory vasomotion and ambient temperature variation on the accuracy of core-temperature estimates by cutaneous liquid-crystal thermometers.

BACKGROUND: Recently, liquid crystal skin-surface thermometers have become popular for intraoperative temperature monitoring. Three situations during which cutaneous liquid-crystal thermometry may poorly estimate core temperature were monitored: (1) anesthetic induction with consequent core-to-peripheral redistribution of body heat, (2) thermoregulatory vasomotion associated with sweating (precapillary dilation) and shivering (minimal capillary flow), and (3) ambient temperature variation over the clinical range from 18-26 degrees C. METHODS: The core-to-forehead and core-to-neck temperature difference was measured using liquid-crystal thermometers having an approximately 2 degrees C offset. Differences exceeding 0.5 degree C (a 1 degree C) temperature range) were a priori deemed potentially clinically important. Seven volunteers participated in each protocol. First, core-to-peripheral redistribution of body heat was produced by inducing propofol/desflurane anesthesia; anesthesia was then maintained for 1 h with desflurane. Second, vasodilation was produced by warming unanesthetized volunteers sufficiently to produce sweating; intense vasoconstriction was similarly produced by cooling the volunteers sufficiently to produce shivering. Third, a canopy was positioned to enclose the head, neck, and upper chest of unanesthetized volunteers. Air within the canopy was randomly set to 18, 20, 22, 24, and 26 degrees C. RESULTS: Redistribution of body heat accompanying induction of anesthesia had little effect on the core-to-forehead skin temperature difference. However, the core-to-neck skin temperature gradient decreased approximately 0.6 degree C in the hour after induction of anesthesia. Vasomotion associated with shivering and mild sweating altered the core-to-skin temperature difference only a few tenths of a degree centigrade. The absolute value of the core-to-forehead temperature difference exceeded 0.5 degree C during approximately 35% of the measurements, but the difference rarely exceeded 1 degree C. The core-to-neck temperature difference typically exceeded 0.5 degree C and frequently exceeded 1 degree C. Each 1 degree C increase in ambient temperature decreased the core-to-fore-head and core-to-neck skin temperature differences by less than 0.2 degree C. CONCLUSIONS: Forehead skin temperatures were better than neck skin temperature at estimating core temperature. Core-to-neck temperature differences frequently exceeded 1 degree C (a 2 degrees C range), whereas two thirds of the core-to-forehead differences were within 0.5 degree C. The core-to-skin temperature differences were, however, only slightly altered by inducing anesthesia, vasomotor action, and typical intraoperative changes in ambient temperature.

Adult↗
PubMed1987

Direct anastomotic assessment for postoperative microvascular monitoring.

An experimental comparison of two techniques for direct monitoring of anastomoses postoperatively is presented. Arterial differential temperature measurements indicated arterial occlusion (n = 24) in island flaps by mean temperature decreases in the affected artery of 0.5 degrees = C, but temperature changes in cases of venous occlusion (n = 17) were small (mean, 0.2 degrees C), inconsistent, and not of predictive value. The technique did not distinguish success (n = 4) from failure (n = 2) in experimental free flaps, and occlusion of deep arteries produced little or no change in the arterial wall temperature. In contrast, an implanted ultrasound Doppler probe reliably indicated arterial and venous occlusion in island flaps (n = 10), because in both circumstances the mean arterial Doppler signal invariably decreased to 0. The two could be distinguished between by changes in Doppler sound and instantaneous signal. In experimental free flaps, success (n = 10) was clearly distinguished from failure (n = 3) by characteristic patterns of Doppler sound and signal. Arterial differential thermometry had serious limitations, but implanted ultrasound Doppler showed great potential as a postoperative monitor applicable to all microvascular procedures.

Anastomosis, Surgical↗
PubMed1994

Laboratory findings in reflex sympathetic dystrophy: a preliminary report.

OBJECTIVE: The purpose of our study was to compare sudomotor and vasomotor indices in patients with clinical reflex sympathetic dystrophy. DESIGN: Vasomotor tone was determined by measuring skin blood flow with laser Doppler flowmeters and skin temperature by infrared thermometry. Resting and evoked sweat output was measured with the quantitative sudomotor axon reflex test. Control values were determined from studies on 223 normal subjects. SETTING: The setting was a tertiary/academic medical center. PATIENTS: There were 12 patients with clinical reflex sympathetic dystrophy in an extremity. MAIN OUTCOME MEASURES: These were skin vasomotor tone and evoked sweat output. RESULTS: Resting sweat output asymmetry was seen in 67% of patients, quantitative sudomotor axon reflex test asymmetry was seen in 75%, and vasomotor changes in 80%. When sudomotor and vasomotor indices were combined, abnormalities were seen in all patients. CONCLUSIONS: Laboratory quantitation of autonomic indices enhances the clinical evaluation of patients with reflex sympathetic dystrophy.

Adolescent↗
PubMed1993

Comparison of ear-based, bladder, oral, and axillary methods for core temperature measurement.

OBJECTIVE: To determine the accuracy and repeatability of ear-based, bladder, oral, and axillary temperature methods. DESIGN: Prospective, descriptive comparison of the accuracy of four temperature methods in relation to pulmonary artery temperature and the repeatability of each method. SETTING: Critical care units of a university teaching hospital. PATIENTS: Convenience sample of 38 adult patients with indwelling pulmonary artery thermistor catheters. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ear-based estimates of core temperature with an infrared thermometer and pulmonary artery, bladder, oral, and axillary temperatures with thermistor-based instruments were made every 20 mins for 4 hrs. Mean offsets (+/- SD) from pulmonary artery temperature for each method were as follows: ear-based 0.07 +/- 0.41 degrees C; bladder 0.03 +/- 0.23 degrees C; oral 0.05 +/- 0.26 degrees C; and axillary -0.68 +/- 0.57 degrees C. The accuracy of each method varied with the level of pulmonary artery temperature. Repeated measurements with all four methods had mean SD values within +/- 0.2 degrees C. CONCLUSIONS: Infrared ear thermometry provided a relatively close estimate of pulmonary artery core temperature, although with more variability than bladder or oral methods, while axillary readings were substantially lower than the pulmonary artery temperature and highly variable.

Adult↗
PubMed1989

An automated dosimetry system for microwave and thermal exposure of biological samples in vitro.

A waveguide exposure system with automated sample temperature measurement is described. This system provides on-line determination of the temperature profile over time of biological samples in vitro. It allows automated computation of the specific absorption rate determined from heating/cooling curves, uses minimally-perturbing thermometry, is biocompatible and can be used for measurements of both microwave and conventional heating.

Electronic Data Processing↗
PubMedDate not supplied

Laboratory and hospital testing of new infrared tympanic thermometers.

A patented approach to infrared thermometry based on the use of a standard pyrosensor has resulted in the development of two new infrared tympanic thermometers, one for professional use, the other for home use. Both were tested to evaluate accuracy in the laboratory and to evaluate equivalence to standards, correlation to standards, and precision in human subjects. Accuracy was found to be well within ASTM standards on both models. Mean ear temperatures were 0.2 degrees C below oral and 0.7 degrees C below bladder temperature. Correlations between ear and oral and ear and bladder temperatures were r = .77 to .84. Repeatability in the same ear was very high at r = .95 (left) and .97 (right). Reproducibility between left and right ear ranged from r = .89 to .92.

Equipment Design↗
PubMed1991

Interstitial irradiation and hyperthermia for the treatment of recurrent malignant brain tumors.

Between June 1987 and June 1989, 29 recurrent malignant gliomas or recurrent solitary brain metastases in 28 patients were treated in a Phase I study of interstitial irradiation and hyperthermia. Patient age ranged from 18 to 65 years, and the Karnofsky Performance Status scores ranged from 40 to 90%. There were 13 glioblastomas, 10 anaplastic astrocytomas, 3 melanomas, and 3 adenocarcinomas. Catheters were implanted stereotactically after computed tomography-based preplanning. Hyperthermia was administered before and after brachytherapy, using one to six 2450- or 915-MHz helical coil microwave antennas and one to three multisensor fiberoptic thermometry probes. The goal was to heat as much of the tumor as possible to 42.5 degrees C for 30 minutes. Within 30 minutes after the first hyperthermia treatment, implant catheters were afterloaded with high-activity iodine-125 seeds delivering tumor doses of 32.6 to 61.0 Gy. Most patients had no sensation of heating. Complications included seizures in 5 patients, reversible neurological changes in 9 patients, a scalp burn in 1, and infections in 3. Of 28 evaluable 2-month follow-up scans, 11 showed definite improvement in the radiological appearance of the tumor, 4 were slightly improved, 7 were stable, and 6 showed tumor progression. Ten patients underwent reoperation for persistent tumor and/or necrosis. Eleven of 28 patients are alive 40 to 97 weeks after treatment. Thirteen patients died of a brain tumor, 2 died of extracranial melanoma metastases, 1 died of new brain melanoma metastases, and 1 died of a pulmonary embolus. The median survival was 55 weeks overall. Median survival has not yet been reached for the anaplastic astrocytoma subgroup. We conclude that interstitial brain hyperthermia using helical coil microwave antennas is technically feasible. The level of toxicity is acceptable, and the computed tomographic response rate is encouraging.

Adenocarcinoma↗
PubMed1984

Monitors for the cutaneous microcirculation.

Scientific evidence is not yet sufficient to justify a large expenditure on equipment simply for clinical monitoring. Despite reservations about reliability, thermometry certainly appears the most cost-effective technique. It is of particular value in monitoring digits. Since these are end organs, spurious information arising because of heat conducted from deep tissues is eliminated, and multiple digits are easily monitored simultaneously. Implantable systems providing direct information relating to the condition of a microanastomosis may eventually prove more versatile and effective clinically than externally applied techniques, although the physiological information which they provide is limited.

Blood Flow Velocity↗
PubMed1996

The effect of cigarette smoking on the survival of free vascularized and pedicled epigastric flaps in the rat.

Microsurgeons suspect that cigarette smoking reduces the survival of free vascularized flaps and replantations, but this has never been proven. This experimental study investigates the effect of smoking on free-flap survival. A fasciocutaneous epigastric flap was used in 30 rats as a free flap and in 30 rats as a pedicled flap. Of each group, 10 rats were smoked 6 weeks before and 2 weeks after surgery, 10 rats were smoked only 6 weeks before surgery, and 10 rats underwent the sham smoking procedure. Also, a distally based dorsal skin flap was cut in all rats, representing a random vascularized flap. Vitality and size of both flaps and patency of the vascular anastomoses were assessed 14 days after surgery. The epigastric flaps were monitored by laser Doppler flowmetry and thermometry during the experiment. Survival of the free vascularized epigastric flaps was significantly lower in smoking rats. All pedicled flaps except one survived. The epigastric flaps only necrosed or survived completely, exactly correlating to the patency of the vascular anastomoses. The mean surviving area of the dorsal flaps was best for nonsmoking rats, worse for only preoperatively smoking rats, and worst for preoperatively and postoperatively smoking rats. The differences were statistically significant. Postoperative laser Doppler flow differed significantly between surviving and dying flaps, affirming the value of laser Doppler flow monitoring in microvascular surgery. In conclusion, this study proves that smoking of cigarettes is detrimental to the survival of free vascularized flaps.

Anastomosis, Surgical↗