Hyperbaric oxygen therapy suppresses hypoxia and reoxygenation injury to retinal pigment epithelial cells through activating peroxisome proliferator activator receptor-alpha signalling.

Retinal ischemia followed by reperfusion (IR) is a common cause of many ocular disorders, such as age-related macular degeneration (AMD), which leads to blindness in the elderly population, and proper therapies remain unavailable. Retinal pigment epithelial (RPE) cell death is a hallmark of AMD. Hyperbaric oxygen (HBO) therapy can improve IR tissue survival by inducing ischemic preconditioning responses. We conducted an in vitro study to examine the effects of HBO preconditioning on oxygen-glucose deprivation (OGD)-induced IR-injured RPE cells. RPE cells were treated with HBO (100% O2 at 3 atmospheres absolute for 90 min) once a day for three consecutive days before retinal IR onset. Compared with normal cells, the IR-injured RPE cells had lower cell viability, lower peroxisome proliferator activator receptor-alpha (PPAR-α) expression, more severe oxidation status, higher blood-retinal barrier disruption and more elevated apoptosis and autophagy rates. HBO preconditioning increased PPAR-α expression, improved cell viability, decreased oxidative stress, blood-retinal barrier disruption and cellular apoptosis and autophagy. A specific PPAR-α antagonist, GW6471, antagonized all the protective effects of HBO preconditioning in IR-injured RPE cells. Combining these observations, HBO therapy can reverse OGD-induced RPE cell injury by activating PPAR-α signalling.

Hyperbaric oxygen preconditioning normalizes scrotal temperature, sperm quality, testicular structure, and erectile function in adult male rats subjected to exertional heat injury.

Testicular hyperthermia has been noted in men who work in high ambient temperatures. Scrotal temperatures above the normal range caused germ cell loss in the testes and resulted in male subfertility. In adult male rats, exercising at a higher environmental temperature (36 °C with relative humidity of 50%, 52 min) caused exertional heat stroke (EHS) characterized by scrotal hyperthermia, impaired sperm quality, dysmorphology in testes, prostates and bladders, and erectile dysfunction. Here, we aim to ascertain whether hyperbaric oxygen preconditioning (HBOP: 100% O2 at 2.0 atm absolute [ATA] for 2 h daily for 14 days consequently before the onset of EHS) is able to prevent the problem of EHS-induced sterility, testes, prostates, and bladders dysmorphology and erectile dysfunction. At the end of exertional heat stress compared to normobaric air (NBA or non-HBOP) rats, the HBOP rats exhibited lower body core temperature (40 °C vs. 43 °C), lower scrotal temperature (34 °C vs. 36 °C), lower neurological severity scores (2.8 vs. 5.8), higher erectile ability, (5984 mmHg-sec vs. 3788 mmHg-sec), higher plasma testosterone (6.8 ng/mL vs. 3.5 ng/mL), lower plasma follicle stimulating hormone (196.3 mIU/mL vs. 513.8 mIU/mL), lower plasma luteinizing hormone (131 IU/L vs. 189 IU/L), lower plasma adrenocorticotropic hormone (5136 pg/mL vs. 6129 pg/mL), lower plasma corticosterone (0.56 ng/mL vs. 1.18 ng/mL), lower sperm loss and lower values of histopathological scores for epididymis, testis, seminal vesicle, prostate, and bladder. Our data suggest that HBOP reduces body core and scrotal hyperthermia and improves sperm loss, testis/prostate/bladder dysmorphology, and erectile dysfunction after EHS in rats.

Quality improvements of antimicrobial prophylaxis in coronary artery bypass grafting.

BACKGROUND: Although the principles of antibiotics prophylaxis are well established, more than 60% of hospitals that joined the international quality indicator project failed to discontinue the use of prophylactic antibiotics within 24h after coronary artery bypass grafting (CABG). Our specific aims are to disseminate the gain obtained from breakthrough series model in knee arthroplasty and abdominal hysterectomy to increase the rate of prophylactic duration not longer than 24h in patients with CABG. METHODS: The control and intervention groups enrolled 55 and 78 patients with CABG before and after the project. Measurements were prophylactic interval and duration, surgical site infection, hospital and antibiotics costs. Two strategies were developed. The key cardiac surgeon was invited to attend quality improvement activities. Knowledge and rationale of medical quality indicators would thus be communicated. Secondly, we proposed a regional symposium in which a level of competition was subconsciously established, and practitioners would present their level of compliance. RESULTS: Instances of prophylactic interval within 1h prior to incision were significantly increased from 66.7% to 97.4%. Rates of prophylactic duration less than 24h were significantly increased from 2.8% to 66.1%. The average hospital cost was reduced by 16.4%, and antibiotics cost was reduced by 91.8%. No significant changes in surgical site infection within 30 d of CABG were observed. CONCLUSIONS: We successfully disseminated the gain of breakthrough project in improving antimicrobial prophylaxis to CABG. By implementing this model, we are able to optimize the timing and duration of antimicrobial prophylaxis in patients with CABG to a level above worldwide average.

Nonparallel cutaneous microcirculatory responses to pharmacologic alterations of systemic arterial pressure in rats.

Both hypotension and hypertension aggravate the damage of reperfusion injury after reconstructive microsurgery. The purpose of this study is to establish a theoretical guide for postoperative blood pressure control in optimizing the cutaneous perfusion and flap survival. Systemic arterial pressure was altered by the intravenous infusion of saline, sodium nitroprusside, phentolamine, and phenylephrine in thirty-two 280-350 g anesthetized Sprague Dawley rats. Power spectral analysis of systemic arterial pressure (SAP) and laser Doppler flowmetry (flux) of epigastric skin were used to reveal the blood pressure and cutaneous blood flow variabilities. Nonparallel responses of cutaneous perfusion and blood pressure were found. The baseline SAP and flux were 126.0 +/- 1.4 mmHg and 57.2 +/- 1.8 au, respectively. Sodium nitroprusside and phentolamine significantly decreased the SAP (71.1 +/- 2.7 and 70.5 +/- 1.5 mmHg, P < 0.0001). However, the corresponding responses in cutaneous perfusion were opposite (56.2 +/- 3.1 au, P = 0.7389 and 36.2 +/- 2.3 au, P < 0.0001). Phenylephrine significantly increased the SAP (171.7 +/- 3.0 mmHg, P < 0.0001) but the flux of epigastric skin was decreased (44.4 +/- 2.6 au, P < 0.0001). Phentolamine and phenylephrine showed negative effects on the systemic cardiac and vascular sympathetic modulations. Sodium nitroprusside had a trend in increasing systemic vasomotor activity. We suggested not using vasoconstrictors in treating intra and postoperative hypotension associated with free flap transfer. Nitric oxide donors are superior to alpha-adrenoceptor antagonists in preserving the cutaneous flap perfusion when treating postoperative hypertension.

Power spectral analysis of perfusion signals on free radial forearm flap transplantation in humans.

Forearm cutaneous perfusion is an established in vivo model in many clinical and basic researches to explore the peripheral circulation. The aim of our study is to characterize the dynamic properties of regional microcirculation after simultaneous denervation and revascularization in free forearm flap transplantations. Serial changes in laser Doppler flow and cutaneous temperature were measured during 14 forearm flap transplantations. Digitalized perfusion data were relayed for power spectral analysis based on the fast Fourier transform. Real time heart rate variability was measured to verify the influence of systemic autonomic nervous modulations. The basal flow expressed a threefold to fourfold increase, from 20.31 +/- 3.25 to 73.79 +/- 11.78 PU, after the transplantation. Frequency domain analysis of cutaneous blood flow variability showed significantly increased high frequency (0.15-0.4 Hz, 55.14% +/- 3.31% to 65.31% +/- 2.78%, P = 0.0035) and decreased very low frequency (0.003-0.04 Hz, 18.61% +/- 2.70% to 9.25% +/- 1.38%, P = 0.0049) power fraction after flap transfer. Simultaneous denervation and revascularization of forearm flaps increased the regional blood flow significantly that was caused by increased high frequency and decreased very low frequency fractional contributions in dynamic regulation of regional cutaneous microcirculation. They are associated with the sympathetic denervation and reactive hyperemia, respectively.

Experience with elastic rubber bands for the tie-over dressing in skin graft.

We derived a dressing using elastic rubber bands to tie over the skin graft. This is a simple, easy to perform, timesaving, inexpensive and reliable method for applying pressure over the skin graft compared with traditional methods. Between September 2002 and August 2004, we have used the present dressing technique in 35 patients with 36 grafts in various parts of the body. We chose this method, because of some anatomic areas, such as back, and buttock, which are frequently quite difficult to maintain pressure dressings in place, minimal movement can cause the skin graft to dislodge. The elastic rubber bands, rather than threads, are used as tie-over. Such a dressing permits expansion and contraction, providing a dynamic quality in the most difficult anatomic locations. The patient group consisted of 23 males and 12 females. The age ranged from 34 to 82 years (mean 52.4 years). Defect size ranged from 3x2.5 to 30x20 cm2 (mean 11.2x7.0 cm2 in size). The average follow-up was 5.8 months (range: 1-12 months). Among the 36 grafts in our study, all grafts except four showed good to excellent results. The mean graft successful rate is 88%. With our procedure no hematoma formation or shearing force (except one case) occurred in this group of patients during the phase of revascularization, there was, hence, good fixation of the graft by the "tie-over" dressing using elastic rubber bands compared with conventional tie-over dressing, especially in skin grafts of the back site of body and at large graft area. However, it is not suitable for the potentially infectious granulation beds, especially near joint area.

Unilateral gracilis myofasciocutaneous advancement flap for single stage reconstruction of scrotal and perineal defects.

BACKGROUND: Extensive defects of the perineal area, with exposure of the testes, are difficult to reconstruct. Numerous reconstruction methods are available, but few provide us with an aesthetically acceptable, thin and pliable cover. The gracilis myocutaneous flap had the disadvantage of an unreliable skin paddle since McCraw's original description. Our method of using a longitudinally orientated gracilis myofasciocutaneous flap with wide incorporation of the perigracilis fascia, provided us a large reliable cutaneous territory and allowed us to repair extensive perineal defects in one single operation. METHODS: Eight patients treated for Fournier's gangrene between 2003 and 2005 were enrolled in the study. All patients underwent early, aggressive surgical debridement followed by surgical reconstruction with a gracilis myofasciocutaneous flap. RESULTS: The size of the defect ranged from 12 cm x 7 cm to 30 cm x 15 cm. Diverting colostomy was performed in six of the eight patients. All patients recuperated well with good coverage of the defects. No wound dehiscence due to excessive tension was seen. Haematoma developed in one patient. One patient developed an abscess in the distal part of the donor thigh three months after the initial flap coverage. CONCLUSION: Gracilis myofasciocutaneous advancement flap provides a good cover for the perineal defect with testicular exposure. It is technically easy and has favourable functional and aesthetic results. It allows the surgeon the ability to reconstruct the perineal and scrotal defects in one single stage.

Time course of cardiovascular neural regulation during programmed 20-sec apnea in rats.

OBJECTIVES: Long-term hypoxia results in hemodynamic breakdown in patients in the intensive care unit; however, intermittent hypoxia causes hypertension in individuals with sleep apnea. The objective of this study was to explore the sequential cardiovascular neural alterations in response to acute hypoxic apnea. DESIGN: The authors conducted a prospective, randomized animal study. SETTING: The study was conducted in a university animal laboratory. METHODS: A programmable apnea model was developed in anesthetized rats, in which a 20-sec period of apnea was produced and subsequently divided into the early (2.0 to 7.9 secs), middle (8.0 to 13.9 secs), and late apneic phases (14.0 to 19.9 secs) and immediate reventilatory phase (20.0 to 25.9 secs). RESULTS: Evident hypoxia developed during 20-sec apnea. Arterial pressure increased in the early apneic phase and returned to control level in the middle phase. Significant hypotension developed in the late apneic phase and deteriorated in the reventilatory phase. Interbeat interval increased mildly along the apneic event. The increase of pressure in the early and middle phases was inhibited by propranolol (1.0 mg/kg intravenously [iv]) but was provoked by phentolamine (2.5 mg/kg iv). The decrease of pressure in the late and reventilatory phases was reversed, at least in part, by phentolamine. Atropine (0.5 mg/kg iv) did not produce discernible effects in the arterial pressure. The increase of interbeat interval was suppressed by propranolol. Power spectral analysis of arterial pressure variability demonstrated significant increases of the low-frequency (sympathetic vasomotor activity) and normalized high-frequency (cardiac sympathetic modulation) power after reventilation. CONCLUSION: Although the sympathetic activity is excited during and after a hypoxic apnea, the immediate pressor effect is related to an inotropic response of cardiac sympathetic regulation, whereas the negative chronotropic and subsequent depressor effect is associated with a failure in the cardiovascular response to sympathetic excitation.

Secondary free-tissue reconstruction for metachronous tumors of the head and neck: techniques, results, and outcomes.

Malignancies of the head and neck are not uncommon in the Far East due to the habit of betel-nut chewing. The development of a second primary neoplasm is a constant fear for those who have had successful treatment of a primary cancer. A total of 82 patients, treated with microvascular reconstruction after surgical resection of head and neck cancer, were studied retrospectively. Twenty-one patients who had repeated reconstructive microsurgery for a second primary head and neck malignancy were enrolled as the study group. Sixty-one patients treated for the first-diagnosed malignancy were considered as the control group. There were no statistical differences between the two groups, either in terms of operation time, hospital stay, successful rate, or complication rate. The results show that, if required, one should not hesitate to repeat the free-tissue transfer after ablating a second primary neoplasm.

Reconstruction of trunk defects with bilobed myocutaneous flap.

This study describes the use of the bilobed myocutaneous (MC) flap for reconstruction of trunk defect. The authors employ this flap because it offers a greater flexibility in the use of available tissue than many other local conventional flaps, is easy to design, safe to elevate, and causes minimal donor-site morbidity. The bilobed MC flaps are based on their main muscular pedicle. The standard bilobed flaps are generally based on a random pattern blood supply, which were restricted to rigid length-to-width ratios to ensure viability. They are usually indicated in the repair of small defects of the nose, and scalp. When we want to apply to reconstruct on the larger trunk defect, especially for the potential to cause life-threatening complications, the bilobed M-C flap might be considered for reconstruction to decrease the potential risk of the complications.

The "Sun window" - a simple and effective alternative to the use of background contrast material during microvascular anastomosis.

A new and simple alternative method, the "Sun window," is introduced for creating a comfortable environment while doing microvascular anastomoses. A prospective randomized study, analyzing the anastomosis time for 34 free radial forearm flaps, was conducted to validate the effectiveness of this method. The time required for doing anastomoses with and without a "Sun window" are 8.74 +/- 1.46 and 10.36 +/- 1.20, respectively, p < 0.01. The results demonstrated that the "Sun window" is an effective method for promoting the patency rate and accuracy of microvascular anastomosis.

Is dextran infusion as an antithrombotic agent necessary in microvascular reconstruction of the upper aerodigestive tract?

Patent microvascular anastomoses are mandatory for a successful free tissue transfer. Dextran 40 is widely used by reconstructive microsurgeons in conjunction with free tissue transfer, to prevent flap loss. Unfortunately, dextran-induced adverse reactions, such as anaphylactoid reactions, adult respiratory distress syndrome, cardiac overload, hemorrhage, and renal damage, remain the major risks in routine use of dextran 40. The authors retrospectively analyzed the patency rates of 55 microvascular tissue transfers of a single microsurgeon after tumor ablation of malignancies of the upper aerodigestive tract between August, 1997 and March, 2001. The patency rates of free flap reconstructions were 96 percent for the dextran-infusion group and 100 percent for the dextran-free group. There was no statistically significant difference between the patency rates of these two groups. The results showed that the routine use of dextran as an antithrombotic agent is not necessary in microvascular reconstruction. The disadvantages of dextran infusion can be effectively prevented.