Results of 1236 endoscopic carpal tunnel release procedures using the Brown technique.

In a series of 1236 patients who underwent endoscopic carpal tunnel releases using the two-portal Brown technique, the results were favorable in 98%, the failure rate was 2%, the instance of iatrogenic injury was 0.08% (one tendon injury), and the overall complication rate was 0.97%. The patients had resolution of carpal tunnel syndrome symptoms in an average of 14 days and returned to work in an average of 15 days. Recurrence rate to date has been 2%, with the longest follow-up of 30 months. These results indicate that this is a safe and efficacious method of treatment for patients with carpal tunnel syndrome who require surgery.

The relationship between timing of repair of disruptions and subsequent aneurysm formation in laser-assisted microvascular anastomoses.

In this study we investigated the effects of duration of bleeding after laser-assisted microvascular anastomoses and the amount of laser energy used to control bleeding on aneurysm formation. Eighty femoral arteries were exposed in 40 Sprague-Dawley rats anesthetized with chloral hydrate. The arteries were transected and then anastomosed end-to-end with three nylon stay sutures followed by irradiation of the vessels with energy from a CO2 laser. The laser power was kept at 90 mW, and each of three segments between stay sutures was exposed for 6 seconds to continuous laser energy. If anastomotic disruption (defined as bleeding after completion of the anastomosis) occurred, it was controlled with pressure over the disrupted site for 10, 25, or 40 seconds. Disruptions were required with exposure to additional laser energy for either 6 (group 1) or 12 seconds (group 2). The anastomoses were inspected at 21 days postoperatively to assess patency and aneurysm formation. Twenty-six of 80 vessels (32%) were anastomosed without the occurrence of disruptions: these 26 vessels had a 100 per cent patency rate and did not develop aneurysms. In group 1, the incidence of redisruption following a primary disruption was the same irrespective of duration of bleeding (4/8, 3/6, and 3/6 for 10-, 25-, and 40-seconds bleeding time, respectively P = NS). Similarly, there was no difference in the incidence of aneurysm formation in this group (0/8, 2/6, and 2/6 for 10, 25, and 40", respectively, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of seroma formation after dissection of musculocutaneous flaps.

Dissection of musculocutaneous flaps is uniformly followed by the formation of seroma if drains are not used. Drains can be colonized and form deep tissue infection if left in place for a long time. In this study we investigated whether talc poudrage could prevent the formation of seroma following dissection of the latissimus dorsi muscle in a canine model. Twelve mongrel dogs were randomized into two groups. Group 1 (n = 6) underwent dissection of the left latissimus dorsi muscle which was rotated as a pedicle flap into the left chest through a second intercostal space thoracotomy. The wound was closed in layers without drains. Group 2 (n = 6) had the same procedure, but before closure of the wound, USP talc was applied to the tissues. All animals received cefazolin (500 mg) Q8h for 48 hours perioperatively. Animals were followed for 1-5 months. Wounds with fluctuation were aspirated as many times as necessary and the amount of fluid was recorded. All Group 1 animals developed seromas, in contrast, only one animal in group 2 had a seroma. There was a significant difference in the amount of fluid aspirated for each animal between the two groups (280 +/- 80 in group 1 vs 25 +/- 25 ml in group 2, P < 0.05). The total amount of fluid drained in group 1 was 1730 ml, whereas only 150 ml was aspirated in group 2. Group 1 animals required a total of 11 aspirations to control seromas, in contrast, only one aspiration was needed in group 2. No abscess was identified at postmortem in either group. Based on the results of this study we conclude that talc poudrage can be safely used to minimize seroma formation after dissection of musculocutaneous flaps.

A multimodality approach lengthens warm ischemic time during aortic cross-clamping.

To evaluate the effects of exsanguination, cerebrospinal fluid drainage (CSFD), steroids alone and in conjunction with CSFD on spinal cord perfusion pressure (SCPP), and neurological outcome following 70 min of normothermic spinal cord ischemia, we monitored proximal (Px BP) and distal (Ds BP) aortic blood pressure, cerebrospinal fluid pressure, and somatosensory evoked potentials (SEP) in 29 mongrel dogs. In all animals Px BP during aortic cross-clamping was controlled with partial exsanguination (40-50% circulating blood volume). Dogs were randomized into four groups (gp): gp 1 (n = 6) control; gp 2 (n = 8) steroids only (methylprednisolone 30 mg/Kg 10 min before aortic occlusion and 4 hr later); gp 3 (n = 8) CSFD only; gp 4 (n = 7) steroids and CSFD. Partial exsanguination effectively controlled Px BP during aortic cross-clamping in all groups. After the statistically significant decrease from preclamp values, mean Px BP did not differ among groups (78.9, 81.2, 80.5, and 80.3 mm Hg, respectively, P greater than 0.05). Mean Ds BP decreased from systemic values to 12.6, 16.8, 16.7, and 17 mm Hg, respectively, after aortic occlusion (P less than 0.05); these values did not differ from one another. CSFP did not change significantly from its baseline value while the aorta was cross-clamped in gp 1; CSFP was significantly reduced to 6.2 mm Hg in gp 2, steroid-treated animals (P less than 0.05 vs gp 1); a further significant reduction in CSFP was noted in gp 3 and 4 undergoing CSFD (0.07 and 0.67 mm Hg, respectively, P less than 0.05 vs gp 1 and 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute limited normovolemic hemodilution can be safely used in a malnourished model.

This study investigates the effects of acute limited normovolemic hemodilution (ALNH) on intestinal healing in a malnourished animal model. Twenty rabbits were randomized into three Groups: Group 1 = control; Group 2 = ALNH (removal 35% blood volume and maintenance of normovolemia with 3:1 crystalloid infusion) followed by retransfusion (RT) after small bowel anastomosis (ANA). Group 3 had a restricted diet for 3 weeks preoperatively to cause a 15 percent to 20 percent weight loss. A six cm segment of small bowel (SB) was resected and anastomosed (ANA) in all animals. Blood pressure (BP), transserosal oxygen tension (TsPao2), hematocrit (Hct), colloid oncotic pressure (COP), wet-to-dry weight ratios (WW/DW), hydroxyproline (OH-Pro) content, and tensile strength (TS) of the ANA and a segment of adjacent SB were determined. BP did not change from baseline (BL) in Group 2 during ALNH; however, it rose significantly after RT (P less than 0.05). BP decreased significantly during ALNH in Group 3 (P less than 0.05) and did not rise above baseline after RT. There was no significant change in TsPao2 from BL within groups during the experiment. The Hct and COP decreased significantly after ALNH in Groups 2 and 3 after ALNH compared to BL (P less than 0.05). After RT the Hct and COP increased and by Day 8 the Hct had risen to BL values in Group 3 but not in Group 2 (P less than 0.05), whereas COP values were not significantly different from BL in either group. There was no difference in WW/DW or TS between or among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Pericardiotomy improves left ventricular compliance during sepsis-induced pulmonary artery hypertension.

Sepsis-induced pulmonary artery hypertension (SIPAH) causes an increase in right ventricular (RV) afterload, dilatation of the RV, leftward shift of the interventricular septum (IVS), and therefore decreases left ventricular compliance (LVC). This study was designed to evaluate the role of pericardiotomy during SIPAH as an alternative to vasodilators (which cause a detrimental increase in shunt fraction) to improve LVC. Systemic and pulmonary hemodynamics, pulmonary function, RV, and LVC were acquired at baseline (BL), during SIPAH with closed pericardium (PAHCP) and after opening the pericardium (PAHOP). Systemic hemodynamics and pulmonary function did not change significantly during the experiment. The infusion of live bacteria induced a significant rise in mean pulmonary artery pressure from 16 +/- 5.3 at BL to 36.8 +/- 3.3 and 35.0 +/- 6.4 mm Hg during PAHCP and PAHOP, respectively, (P less than 0.05). Pulmonary vascular resistance index and right ventricular stroke work index (RVSWI) displayed a similar rise in response to SIPAH (P less than 0.05 vs BL). Pericardiotomy did not affect pulmonary hemodynamics or RVSWI. Right ventricular contractility did not increase following pulmonary hypertension while the pericardium was closed (440 +/- 78 vs 410 +/- 125, P less than 0.05); however, it rose, although not significantly, to 615 +/- 326 after pericardiotomy. RV time tension index displayed a rise during SIPAH with the pericardium intact and returned to baseline values after pericardiotomy; however, these changes were not significant. RVC did not change significantly throughout the experiment. In contrast, LVC decreased significantly after SIPAH and significantly improved after pericardiotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal mammary coronary artery anastomosis by CO2 laser: an acute experimental study.

This study was designed to determine the feasibility of anastomosing the internal mammary artery (IMA) and coronary artery with a carbon dioxide laser in a canine model. Twenty-two mongrel dogs were randomly assigned to two groups: group I (n = 11) underwent laser-assisted vascular anastomosis (LAVA) of the left IMA to the left anterior descending (LAD) coronary artery, whereas in group II (n = 11) the anastomosis was done with the conventional technique (handsewn). Laser methodology was used to micro-weld vessels utilizing a power of 200 mW with a spot size of 500 mu, producing an effective power density of 102 W/cm2 and energy fluence of 9,172 joules/cm2 in a continuous mode at a distance of 2 cm. The short-term patency rate, measured at 2 hours after completion of the anastomosis, was 100% in both groups. The time required to perform the LAVA in group I was significantly shorter than group II (6.27 +/- 0.47 vs 11.6 +/- 0.67 min, p less than 0.05). The mean anastomotic bursting pressure in group I was significantly lower compared to group II (348 +/- 8 vs 402 +/- 9 mmHg, p less than 0.05). Histologic evaluation of all vessels showed moderate thermal injury of the adventitia and media in the laser group. Scanning electron microscopy exhibited a smooth anastomotic area in group I, whereas endothelial and perianastomotic changes with multiple needle craters occurred in group II (conventional anastomosis).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of arachidonic acid metabolites in oleic acid induced pulmonary injury in a canine model. Effect of ketoconazole (thromboxane synthetase inhibitor).

This study was designed to investigate the effects of ketoconazole, a thromboxane synthetase inhibitor, on pulmonary and systemic hemodynamics and pulmonary function in experimental respiratory distress syndrome. Pulmonary artery infusion of oleic acid (PAIOA), 0.1 ml/kg, was used to cause lung injury. Ten dogs were randomized into two groups (Gps): Gp I (n = 5) acted as control, whereas Gp II (n = 5) were treated with IV ketoconazole (2.5 mg/kg bolus then 10 mg/kg/hour for 2.5 hours). Hemodynamics, extravascular lung water (EVLW), serum levels of PGE2, and TxB2 were obtained at baseline (BL) and at 30-minute intervals for 2.5 hours (T30-T150). After 30 minutes of PAIOA the mean arterial pressure (MAP) decreased significantly in both Gps (131 +/- 17 vs. 88 +/- 9 mmHg Gp 1, 119 +/- 9 vs. 79 +/- 8 mmHg Gp II, P less than 0.05); however, while MAP returned to BL values in Gp II, it remained significantly lower throughout the experimental interval in Gp I. Mean pulmonary artery pressure (MAP) was not significantly affected by PAIOA in either Gp, while pulmonary vascular resistance increased significantly from BL at T120 in Gp II. Pulmonary function measured by partial pressure of arterial O2 (PaO2) and extravascular lung water (EVLW) were significantly affected by PAIOA. There was a significant decrease in PaO2 (66 +/- 6 vs. 96 +/- 8 mmHg, Gp I and 60 +/- 7 vs. 100 +/- 6 mmHg, Gp II) as well as an increase in EVLW (604 +/- 61 vs. 135 +/- 9 ml, Gp I and 641 +/- 110 vs. 117 +/- 18 ml, Gp II) in both Gps.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid drainage and steroids provide better spinal cord protection during aortic cross-clamping than does either treatment alone.

We investigated whether intravenous methylprednisolone (30 mg/kg) before 30 minutes of aortic cross-clamping and after 4 hours could enhance the effects of cerebrospinal fluid drainage on spinal cord perfusion pressure and postoperative paraplegia when proximal blood pressure was controlled with sodium nitroprusside and partial exsanguination. Dogs were randomized into three groups: group 1 (n = 6), control; group 2 (n = 7), steroids; and group 3 (n = 6), steroids with cerebrospinal fluid drainage. During aortic cross-clamping, blood pressure proximal to the clamp decreased significantly in each group compared with baseline (p less than 0.05), but did not differ among groups (group 1 = 82.2, group 2 = 82.1, group 3 = 86.6 mm Hg, p greater than 0.05). Mean distal pressure decreased from systemic values to 8.4, 8.5, and 3.7 mm Hg, respectively, after aortic cross-clamping (p less than 0.05); these values did not differ from one another (p greater than 0.05). During aortic cross-clamping, cerebrospinal fluid pressure in groups 1 and 2 did not differ significantly compared with baseline (12.2 versus 8.2, 14.2 versus 10.7 mm Hg, p greater than 0.05), whereas in group 3 the baseline cerebral spinal fluid pressure of 10.7 mm Hg decreased to 0.4 mm Hg (p less than 0.05). Spinal cord perfusion pressure in group 3 was significantly higher than in groups 1 and 2 (3.3 versus -3.9 and -5.7 mm Hg, p less than 0.05), but did not differ between groups 1 and 2 (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sodium nitroprusside on spinal cord perfusion and paraplegia during aortic cross-clamping.

To evaluate the effects of sodium nitroprusside (SNP) on hemodynamics, cerebrospinal fluid dynamics, and neurological outcome after 30 minutes of thoracic aortic occlusion, we monitored proximal and distal blood pressure, cerebrospinal fluid pressure, spinal cord blood flow, and somatosensory evoked potentials. In group 1 (n = 6), no attempts were made to control proximal hypertension, whereas in group 2 (n = 6), proximal blood pressure was controlled with intravenous infusion of SNP. There was no significant difference in proximal or distal blood pressure or cerebrospinal fluid pressure between the two groups at baseline. During the crossclamp interval, the mean proximal aortic pressure rose from 108 +/- 21 to 146 +/- 14 mm Hg (p less than 0.001) in the control group, whereas the mean blood pressure in the SNP group was maintained at 99.8 +/- 12 mm Hg (p = not significant compared with baseline blood pressure). Mean distal aortic pressure decreased from systemic values to 23 +/- 7 mm Hg in control animals and to 11 +/- 5 mm Hg in the SNP group (p less than 0.005). In the latter group, cerebrospinal fluid pressure increased significantly from 10.6 +/- 1.9 to 20.1 +/- 5.5 mm Hg (p less than 0.005). In animals receiving SNP, spinal cord blood flow was decreased in the lower spinal cord segments and increased in the upper cord segments. When compared with controls, this difference did not reach significance.(ABSTRACT TRUNCATED AT 250 WORDS)