Effect of age and repeated hyperbaric oxygen treatments on vagal tone.

OBJECTIVES: To evaluate the influence of repeated hyperbaric oxygen (HBO2) exposures and age on vagal response to hyperbaric oxygenation, and to evaluate the timing of changes in vagal activity during the treatments. STUDY DESIGN: Open, controlled, non-randomized study. METHODS: Heart rate variability of 23 patients with chronic osteomyelitis or radionecrosis of the jaw or reconstructive surgery of the facial region was studied during repeated treatments. During each treatment, the patients were exposed to HBO2 at 2.5 ATA and heart rate variability was measured using power spectral analysis before compression, three times at 2.5 ATA and during and after decompression. The patients were grouped according to age (Cut-off point 50 years). Statistical analysis was carried out using analysis of variance for repeated measurements. RESULTS: Repeated exposures did not change vagal response to hyperbaric oxygenation. Vagal activity measured by HF power increased significantly in both age groups during the HBO2 exposures but there were no significant difference between the groups in the response. However, the level of HF power was significantly higher in the subjects under 50 years old. Significant differences between consecutive measurements were related to pressure changes. CONCLUSIONS: Repeated therapeutic HBO2exposures are not causing permanent changes in vagal control of the heart. Vagal responsiveness to hyperbaric hyperoxia is preserved in advanced age.

Permanent in vitro growth is associated with poor prognosis in head and neck cancer.

OBJECTIVE: The propensity of head and neck carcinomas to grow in vitro and to form a permanent cell line varies. It is not known whether the outcome of patients whose cancer gives rise to permanent in vitro growth differs from that of patients whose cancer cells fail to grow in vitro. The purpose of this study was to find out whether tumor cell capability for in vitro growth is associated with prognosis in head and neck cancer. MATERIAL AND METHODS: The study group consisted of 30 patients treated for head and neck cancer at the University Central Hospital of Turku between 1987 and 1994, and whose tumor samples had produced a permanent cell line in our laboratory. A control group was selected from patients treated during the same time period and with the same protocols in the same department. The controls were selected on the basis of similar tumor localization, TNM status, histological grade, age, gender and general condition. Tumor samples from 14 of the 30 control patients were also cultured, but did not result in a permanent cell line. The median follow-up time was 54 months in the study group and 52 months in the control group. RESULTS: The 3-year survival rate of the patients whose cancer gave rise to in vitro growth was only 19%, compared to 68% among the controls (p = 0.001). In a multivariate analysis the propensity of cancer cells to grow in vitro had independent prognostic value, the relative risk of death (RR) being 1.95 (95% CI 1.11-3.42) when compared to cancers that did not produce a cell line. Of the other factors tested, only the primary tumor size (RR 1.75; 95% CI 0.97-3.16) and the blood hemoglobin level at diagnosis (RR 0.97; 95% CI 0.95-1.01) were possibly independently associated with survival. CONCLUSIONS: The results suggest that the capability of cancer cells for in vitro growth has prognostic significance in head and neck cancer, and that cancer cells that are able to survive and grow in in vitro conditions behave aggressively in vivo. The independence of cancer cells from the paracrine signals produced by the neighboring host cells may enhance cancer cell survival and the metastatic potential in vivo.

Effect of hypothermia on blood-flow responses in pedicled groin flaps in rats.

Cooling is widely used for preserving tissues such as kidneys before transplantation and for preserving extremities before replantation. Hypothermia has also been shown to be effective in the temporary storage of free flaps. However, in the intact living body, cooling can be damaging to tissue and the body system. We used a custom-designed clamping method (after flap elevation, occlusion and release of the flap-feeding artery) and continuous laser Doppler flowmetry to investigate the effects of hypothermia on blood flow and postocclusive reactive hyperaemia in the flaps. The animal model used was the partially elevated epigastric flap of adult Sprague-Dawley rats. In the hypothermia group (n=12), the core temperature and the flap temperature were allowed to fall during anaesthesia. At core temperatures of 34.58 degrees C and 338 degrees C and after rewarming of the rat, the feeding artery was occluded for 30 s and 120 s to observe the changes in blood flow and postocclusive reactive hyperaemia in the flap. In the control group (n=12), the core temperature was maintained at more than 378 degrees C throughout the experiment. To compare the flap blood-flow responses to occlusion of the femoral artery in the hypothermia group and the control group, the postocclusive reactive hyperaemia periods (i.e. blood flow above baseline after clamp release) were analysed. Statistical analysis of the responses showed that the magnitude (P=0.024), duration (P<0.001) and amplitude (i.e. peak flow) (P=0.037) of postocclusive reactive hyperaemia were significantly decreased in the hypothermia group. Our results suggest that hypothermia significantly decreases blood flow and postocclusive reactive hyperaemia in the rat epigastric flap. This may increase the risk of ischaemic flap complications unless rewarming is performed.

Repair of orbital floor fractures with bioactive glass implants.

PURPOSE: The ideal management of orbital floor fractures has been highly controversial. Many implants, both autogenous and alloplastic, have been used to span the defects. This study evaluated the use of bioactive glass implants (BAG-implant, S53P4; Abmin Technologies Ltd, Turku, Finland) for the repair of orbital floor defects caused by blunt facial trauma. PATIENTS AND METHODS: This retrospective review of 36 patients was carried out from 1995 to 1999. All patients were diagnosed with an orbital floor fracture or a large orbital blowout fracture. The BAG-implant was placed over the defect, using a subciliary or transconjunctival approach. No screw fixation was used when the implant was the correct size. Follow-up examination was done at 1 and 3 months after surgery. Twenty-eight (82%) of the patients were also seen at one-year follow-up (21 men and 7 women). RESULTS: The implants did not cause a foreign body reaction in the bone or soft tissue. There was no sign of resorption or infection, nor postoperative extrusion, hemorrhage, or displacement of the implant. Diplopia was seen preoperatively in 17 cases (61%) and postoperatively in 5 cases (18%). In 1 patient, the implant was removed 3 months after operation because of diplopia. Infraorbital nerve paresthesia was seen preoperatively in 9 patients (32%) and postoperatively in 5 patients (18%). The functional and cosmetic results were good at the 1-year follow-up. CONCLUSION: The BAG-implant is a well-tolerated material in orbital floor reconstruction. It provides a favorable environment for an uncomplicated healing process because it is bioactive and biocompatible and because it causes new bone formation.

Changes in blood flow in the partially elevated epigastric pedicled flap in response to occlusion of the femoral artery in rats.

In this study, the authors used a custom-designed clamping method and laser Doppler flowmetry to investigate the short-term autoregulatory patterns of blood flow (BF) in partially elevated pedicled epigastric flaps in rats (n=11). The femoral artery was clamped for 30, 60, 120 and 180 sec directly after flap elevation and 40 to 80 min after flap elevation. Changes during and after clamping indicate the functioning of autoregulatory factors in the vessels of the epigastric partially elevated flap. The longer the clamp ischemia is in a flap, the greater (p < 0.0001) is the need for a compensatory increase in BF and for a longer time (p < 0.0001) in the flap after clamp release. They compared the responses of BF directly after flap elevation with those 40 to 80 min after flap elevation. The results suggest a significant increase in the autoregulatory capacity of the pedicled partially elevated flap in measurements performed 40 to 80 min after flap elevation (p = 0.043). They conclude that the novel clamping method seems to be reliable when studying the short-term autoregulatory patterns of the epigastric partially elevated pedicled flap.

In vivo model for frontal sinus and calvarial bone defect obliteration with bioactive glass S53P4 and hydroxyapatite.

An in vivo model was developed to investigate the usability of a frontal sinus and a calvarial bone defect obliteration with bioactive glass S53P4 (BG) and hydroxyapatite (HA) granules. Roofs of 21 Elco rabbit frontal sinuses were drilled open from 4 separate holes using a standard method, and the sinuses, located in pairs, in frontal bone were filled with BG on one side and with HA on the other side. Two parallel posterior defects were covered with a pedicled periosteum flap, and 2 anterior defects with a free flap. The stability of materials, new bone, and connective tissue formation were observed with histomorphometry, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), and X-ray pictures at 1, 3, 6, and 12 months postoperatively. The results showed more rapid resorption of filling material (p = 0.019) and new bone formation (p = 0.0001) in the defects filled with BG than in the corresponding HA-filled defects studied by histomorphometry throughout the study. New bone formation and resorption of materials were faster in defects covered by a pedicled flap than by a free periosteum flap. The results were supported by SEM histomorphometric and radiologic analysis. Both bioactive materials studied were well tolerated in frontal sinuses and in calvarial bone defects. The experimental model showed the influence of early periosteum vascularization on accurate frontal sinus filling and the healing process in rabbit frontal sinuses.

Clinical follow-up method for frontal sinus obliteration with bioactive glass S53P4.

A clinical follow-up method was developed to investigate the behavior of a massive amount of bioactive glass S53P4 (BG) clinically used in frontal sinus obliteration. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and in a buffer containing tris-hydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned both wet in the solutions and dried by computer tomography (CT), and the scans were analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS-c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease of Hounsfield units (HUs) in ROI analysis (p < 0.0001). The level of HUs was lower with dried than with wet BG (p < 0.0001). The results were compared for clinical ROI analysis of patients with obliterated frontal sinuses up to 48 months and they were parallel. The follow-up method seems to indirectly reveal the behavior of BG and the healing process in the obliterated cavity.

Reconstruction of orbital floor fractures using bioactive glass.

INTRODUCTION: The management of orbital floor fractures continues to be debated. Bioactive glasses and glass-ceramics are in the new group of materials developed for the repair of bone defects which are beyond any innate healing capacity due to their size. OBJECTIVE: We compared the use of alloplastic implants (bioactive glass) with conventional autogenous grafts (cartilage--plus or minus Iyophilized dura) for the repair of orbital floor defects after trauma. MATERIAL AND METHODS: Twenty-eight patients having orbital floor fractures with persistent diplopia, enophthalmos, and/or infraorbital nerve paraesthesia were operated on from 1991 to 1995 at Turku University Central Hospital. Reconstruction was either with bioactive glass (S93P4) or autogenous cartilage implants. RESULTS: Postoperative tomograms in the 28 patients showed adequate maintenance of orbital and maxillary sinus volume without any evidence of resorption in either group. None of 14 patients in the study group had any evidence of dystopia or complications relating to implants follow-up. One had infraorbital nerve paraesthesia and another had entropion postoperatively. Among the 14 control subjects there were three cases of persistent diplopia, two of infraorbital nerve paraesthesia and one of enophthalmos. CONCLUSION: Bioactive glass implants are well-tolerated and seem to be a promising repair material for orbital floor fractures. Their use leads to less morbidity as no donor site operation is needed. Also it provides favourable healing as it is bioactive, biocompatible and causes new bone formation.

Experimental follow-up model for clinical frontal sinus obliteration with bioactive glass (S53P4).

Bioactive glass S53P4 (BG) is an osteoconductive allograft material. Since 1990, BG has been used in the obliteration of frontal sinuses in more than 30 consecutive patients. The patients have been monitored regularly with clinical examinations, computer tomography (CT) scans, laboratory tests and, in a few cases, biopsies have also been obtained. The material has been well tolerated and no loss of volume of obliteration material has been seen in the obliterated sinuses. However, in repeated CT monitoring and with Region of Interest (ROI) analysis, a decrease in the density of the obliteration material inside the frontal sinuses has been seen. In the present study, the clinical conditions after an obliteration operation were simulated and the behaviour of the BG in the obliterated area was observed. The aim was to study whether it is possible indirectly to estimate the resorption of a massive amount of BG with ROI analysis for monitoring the clinical success of the treatment. Thus two sizes of granules (0.63-0.8 mm and 0.8-1.0 mm) in eight separate BG amounts, weight 25 g, were tested in simulated body fluid (SBF) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG amounts were scanned with CT and the slices analysed using the ROI technique at 1, 3 and 6 months. The cumulative loss of Si and P in SBF was significant during the study (p < 0.0001) and it was stronger with smaller than with larger granules (p < 0.0001). This was shown correspondingly by the decrease of Hounsfield units (p < 0.0001) in ROI analysis. The method seems reliably to reveal the resorption of BG for clinical purposes.

Changes in blood flow in the epigastric free flap after microsurgical artery anastomoses in rats.

A number of clinical disorders of free vascularized flap are presumed to reflect insufficient blood flow (BF) or an inadequate range of vascular responsiveness. We compared the changes in BF in a pedicled and free epigastric flap, directly after and 90 min after performing microsurgical artery anastomoses. We used the clamping method and laser Doppler flowmetry in six Sprague-Dawley rats. The BF response curves shortly after re-anastomosing of the artery differ markedly from those in a pedicled flap model and curves registered 90 min after performing the anastomosis. We conclude that the clamping method is reliable and reproducible when studying the short-term autoregulatory BF patterns of epigastric pedicled and free flaps.

In vitro model for frontal sinus obliteration with bioactive glass S53P4.

An in vitro model was used to investigate the behavior of a massive frontal sinus obliteration with bioactive glass S53P4 (BG) for clinical purposes. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and a buffer containing trishydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned by computer tomography (CT) and the scans analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS -c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease in Hounsfield units (HU) by ROI analysis (p < 0.0001). In SBF-soaked BG masses, the CaP-layer occurred on the uppermost granules, and in TRIS-c.a at 3-6 months, on the granules in the center and lower parts. The decrease of HU seems to reveal indirectly the resorption of BG.

Effect of carbogen inhalation on peripheral tissue perfusion and oxygenation in patients suffering from sudden hearing loss.

The effects of repeated carbogen inhalation on peripheral tissue perfusion and oxygenation were assessed in 5 patients suffering from sudden hearing loss by means of continuously measured subcutaneous tissue oxygen and carbon dioxide tension, transcutaneous oxygen tension, laser Doppler red cell flux, and fingertip temperature. The subcutaneous oxygen tension increased clearly during the carbogen inhalation periods, and also, a smaller increase in subcutaneous carbon dioxide tension was simultaneously noticed. The changes in transcutaneous oxygen tension were even greater and the latency was shorter as compared with the subcutaneous gas tensions. The laser Doppler measurements showed no signs of vasoconstriction during the study. In conclusion, carbogen inhalation increases peripheral tissue oxygenation without microvascular vasoconstriction and with only a minor retention of carbon dioxide.

A modified protocol for early treatment of osteomyelitis and osteoradionecrosis of the mandible.

BACKGROUND: The treatment of osteoradionecrosis (ORN) and early chronic osteomyelitis (COM) of the mandible and maxilla is controversial. Hyperbaric oxygen (HBO) at two to three times the atmospheric pressure at sea level can result in tissue oxygen tension of almost 400 mmHg. Herewith HBO increases oxygen supply in hypoxic tissue, thus inducing fibroblastic proliferation and capillary formation. METHODS: From 1981 to 1991, we used a monoplace chamber and since 1992, we have also had a multiplace chamber for HBO treatment. Hyperbaric oxygen was given at 2.5-2.8 atmosphere absolute pressure (ATA) for 90-120 minutes, once per day. The patients had five to 10 preoperative and five to seven postoperative sessions. Surgical therapy consisted of decortication of the affected bone, subsequently covered with a free periosteal transplant from the tibia. RESULTS: Thirty-six patients with ORN and 33 with COM of the mandible and maxilla was treated with this protocol. The median follow-up time in this material is 34 months, with a minimum of 10 months. Thirty-six ORN patients (92%) and 26 COM patients (79%) have remained symptom-free after the first treatment period. Three failed ORN patients were successfully treated with a free microvascular flap. The seven failed COM patients have been retreated, and five of them have occasional clinical symptoms. CONCLUSIONS: Hyperbaric oxygen is a promising adjunct to surgery in the treatment of mandibular and maxillary ORN and COM. Using this protocol, the necessary HBO treatment sessions have been reduced from earlier protocols, without adverse effect on the outcome.

Obliteration of the frontal sinus cavity with bioactive glass.

BACKGROUND: Bioactive glass (BG) is a glass ceramic material. It has been used as surgical bone replacement material in ear and oral surgery, orthopedics, and dentistry. METHODS: Bioactive glass was used as obliteration material in a series of osteoplastic frontal sinus operations on 10 patients suffering from chronic frontal sinusitis, which other, more-conservative treatment modalities had failed to cure. RESULTS: Bioactive glass is easy to handle, and complete obliteration of all sinusal recesses and excavations is easily achieved. No adverse effects of the implant material have been seen over a mean follow-up period of 5.0 years. One patient with a local recurrent infection in the outer table of the sinus was reoperated on 5 months after primary surgery. Repeated postoperative computed tomographic scans analyzed by digital region-of-interest (ROI) selection showed no remarkable changes in the frontal sinus cavities but a slight, yearly decrease in the density of the occlusion material. Laboratory monitoring of patients and histopathologic examination of two postoperative biopsy specimens indicated that the material is well tolerated and stable. CONCLUSIONS: Bioactive glass is a promising and well-tolerated bone graft suitable for osteoplastic frontal sinus operations. Total accurate obliteration of the sinus is achieved with different sizes of granules and blocks. The results of the obliteration are maintained owing to the stability of the material.

Operative treatment of frontal sinusitis.

When the medical therapy fails trephination is the primary operation indicated in acute eroding sinusitis when drainage is necessary to avoid severe complications. In recent years also endoscopic transnasal surgery has been recommended for exenteration of the underlying disease in the ostiomeatal unit as well as for opening of the obstructed nasofrontal duct in acute phase of the disease. In Turku University Central Hospital endoscopic frontal sinus surgery is still reserved for cases with prolonged or delayed disease performed as a secondary operation after trephination and CT examination. Failures are common after these operations and both types of surgical treatment may be needed. Three percent of our patients developed a persistent chronic infection inside the frontal sinus. In these cases external osteoplastic approach is recommended. In these operations we have used bioactive glass as obliteration material with promising clinical results.

Microvascular free flaps in head and neck cancer surgery in Finland 1986-1995.

Microvascular free tissue transfer has in many cases replaced classic flap techniques and is now an established workhorse for head and neck reconstructions. In this retrospective study the over 300 patients, who had microvascular free flap reconstructions in head and neck cancer surgery in Finland during a 10-year period (1986-1995) were reviewed. The operations were performed in the University Hospitals by plastic surgeons, ENT specialists or maxillofacial surgeons. The cases consisted of defects resulting from resection of oral cavity tumors (63%), mid- or upper-face and skullbase tumors (20%) and hypopharyngo-esophageal tumors (17%). The series includes a wide range of flap types and analyses flap outcome and complications. A total of 313 cases was reconstructed by 317 flaps (forearm flaps 47%, latissimus dorsi flaps 19%, free jejunum or colon transfers 15%, free iliaca crest flaps 8% and other flaps 11%). Thrombosis of one of the vessels and haematoma were the most frequent causes of failure in microvascular free tissue transfer. A total flap necrosis occurred in 27 (8.5%) and a partial necrosis in 12 (4%) patients. The most reliable flap in terms of survival was the radial forearm flap. The ever-improving success of microvascular free tissue transfer has made it a useful procedure for head and neck reconstructions. There is also a growing need for microvascular team surgery in the field of head and neck cancer therapy.

Microvascular free tissue transfers after preoperative irradiation in head and neck reconstructions.

Surgical reconstruction of large head and neck tumors involves great problems. Preoperative irradiation increases the risk of postoperative complications. The use of microvascular free flaps has definitive advantages over conventional reconstruction techniques and permits immediate preoperative high-dose radiation therapy. Eighty-eight patients, 55 (62%) men and 33 (38%) women, with head and neck tumors underwent microvascular reconstruction at the Turku University Central Hospital in 1985-1995; 77 of them were irradiated before surgery. All irradiated patients underwent primary reconstruction. The preoperative radiation dose was 50-65 Gy. The free tissue transfer was successful in 77 (88%) of the 88 patients. The success rate was 87% in irradiated patients and 91% in nonirradiated patients. Free tissue transfers are suitable for one-stage reconstruction in selected patients such as those receiving high-dose preoperative irradiation. The transfer of microvascular free flaps to the head and neck has become the most common reconstruction method owing to its increasing success rates as well as its excellent esthetic and functional results.

The success rate of free flaps after preoperative irradiation in head and neck reconstruction.

BACKGROUND AND AIMS: The reconstructive treatment of large head and neck tumours involves serious problems. Preoperative irradiation increases the risk of postoperative complications. Microvascular free flaps offer definite advantages over conventional reconstruction techniques and permit immediate preoperative high-dose radiation therapy. MATERIAL AND METHODS: In 1985-1996, at the Turku University Central Hospital, 101 patients, 61 (60%) men and 40 (40%) women (age range 15-79 years, mean 61 years), with head and neck tumours, underwent microvascular reconstructions, and 90 of them were irradiated before surgery. All irradiated patients underwent primary reconstruction immediately after resection. The total irradiation dose was about 60 Gy, usual range 50 to 65 Gy. The patients were operated on 3 to 5 weeks after discontinuation of irradiation therapy. RESULTS: Of the whole material of 101 free flaps, 89 (88%) were transferred successfully. The success rate in irradiated patients was 88% and in nonirradiated patients 91%. Reoperation had to be performed within twelve hours in three cases, with good results. Only two hernias occurred as donor complications (2%). Two of the patients died postoperatively (2%). Partial flap necrosis occurred in five patients and five patients underwent another reconstruction using a new free flap or with conventional reconstruction techniques. CONCLUSIONS: Free flaps are often the only acceptable choice in extensive head and neck primary reconstructions after irradiation. Microvascular free tissue transfers to the head and neck after preoperative irradiation has become the accepted method of reconstruction as a result of increased success rates with superior aesthetic and functional results.