Mm Hg Of Negative Pressure Research Articles

Manometric Intraocular Pressure Reduction with Negative Pressure Using Ocular Pressure Adjusting Pump Goggles

The Ocular Pressure Adjusting Pump is a novel, non-invasive and non-pharmacological intraocular pressure (IOP)-lowering device consisting of goggles attached to a negative pressure (NP) pump. This study aimed to determine the effect of negative pressure in Ocular Pressure Adjusting Pump goggles on IOP using continuous direct manometry. Prospective, single-arm, single center, basic physiological research trial. Adult patients undergoing cataract surgery. Direct manometry was performed via an anterior chamber cannula attached to an IOP sensor. This was placed just prior to each subject's previously scheduled cataract surgery. IOP was continuously monitored every 0.5 seconds through the following sequence of 30 seconds each: baseline IOP measurement, NP -10 mmHg, NP off, NP -20 mmHg, and NP off. IOP response to application of negative pressure. All seventeen subjects had a dose-dependent reduction in IOP, with a mean IOP decrease from 16.9 to 11.3 (33%) with -10 mmHg of NP and from 15.7 to 7.7 (51%) mmHg with -20 mmHg of NP. IOP returned to baseline for each cycle when NP was discontinued. There were no patients with increased IOP. Negative pressure with the Ocular Pressure Adjusting Pump results in a consistent dose-dependent reduction in IOP, with return to baseline IOP when NP is discontinued.

Traumatic Degloving Wounds Treated With Low Continuous Wall Suction Drainage: A Novel and Effective Technique to Prevent Recurrence.

Soft tissue degloving wounds overlying fractures present a technical surgical challenge and have a high rate of recurrence. Despite several current treatment methods, there remains a need for improved therapies to address this complex issue. The purpose of this study was to introduce a novel technique for managing soft tissue degloving wounds in the setting of fractures requiring operative fixation. Eleven consecutive patients with soft tissue degloving wounds overlying operatively managed fractures were treated with our novel technique for "dead space" elimination in the peri-operative period. The technique entails placing Jackson Pratt drain(s) within the degloving wound during operative debridement and placing them to low continuous wall suction postoperatively. This patient series shows that the application of 40 to 60 mm Hg of negative pressure allows for thorough drainage of the hemolymphatic fluid collection and elimination of dead space, allowing the delaminated tissue layers to heal together and preventing recurrence. [Orthopedics. 2023;46(4):e257-e263.].

A Prospective Randomized Study Comparing Manual and Wall Suction in the Performance of Bronchoalveolar Lavage

Background: Bronchoalveolar lavage (BAL) may be performed using a hand-held syringe or wall suction. Objectives: The aim was to study BAL volume and diagnostic yields based on BAL technique. Methods: A total of 220 consecutive patients undergoing BAL at our center were included. Manual aspiration was performed in 115 patients (group 1), and wall suction (<50 mm Hg of negative pressure) was used in 105 patients (group 2). All bronchoscopies were performed under conscious sedation applying topical anesthesia with lidocaine. Three 50-ml sterile saline aliquots were instilled in all patients. Results: The mean total amount of fluid recovered was 67 ± 20 ml in group 1 and 55 ± 22 ml in group 2 (p < 0.001). More patients in the manual aspiration group met American Thoracic Society criteria (recovery of ≥30% of instilled fluid) for an optimal BAL (81 vs. 59%; p < 0.001). The quantity of recovered fluid was also related to BAL location (p < 0.001) and radiologic findings (p = 0.002). Forty-eight (22%) BALs were diagnostic (23 in group 1 and 25 in group 2), including 37 positive bacterial cultures, 6 positive stains for Pneumocystis, and 5 cases of malignancy. No statistically significant difference in diagnostic yield was observed between the two groups. A BAL diagnosis was more likely in patients with certain radiologic (p = 0.033) and endoscopic findings (p = 0.001). When taking into account all bronchoscopic techniques performed during the procedure (e.g. biopsies, brushing, etc.), bronchoscopy was diagnostic in 37% of patients. Conclusions: Manual aspiration is superior to wall suction during BAL yielding a larger quantity of aspirate. Diagnostic yields are similar for both techniques.

Surgical Pearl: Use of the Vacutainer as a closed, active, surgical drain

J Am Acad Dermatol 2003;48:933-4.

Decreased cardiopulmonary baroreflex sensitivity in Chagas' heart disease.

No study has been performed on reflexes originating from receptors in the heart that might be involved in the pathological lesions of Chagas' heart disease. Our study was undertaken to analyze the role of cardiopulmonary reflex on cardiovascular control in Chagas' disease. We studied 14 patients with Chagas' disease without heart failure and 12 healthy matched volunteers. Central venous pressure, arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance were recorded during deactivation of cardiopulmonary receptors. By reducing central venous pressure by applying -10 and -15 mm Hg of negative pressure to the lower body, we observed (a) a similar decrease of central venous pressure in both groups; (b) a marked increase in forearm vascular resistance in the control group but a blunted increase in the Chagas' group; and (c) no significant changes in blood pressure and heart rate. To analyze cardiopulmonary and arterial receptors, we applied -40 mm Hg of lower-body negative pressure. As a consequence, (a) central venous pressure decreased similarly in both groups; (b) blood pressure was maintained in the control group, whereas in patients with Chagas' disease, a decrease in systolic and mean arterial pressure occurred; (c) heart rate increased in both groups; and (d) forearm vascular resistance increased significantly and similarly in both groups. Unloading of receptors with low levels of lower-body negative pressure did not increase forearm vascular resistance in patients with Chagas' disease, which suggests that the reflex mediated by cardiopulmonary receptors is impaired in patients with Chagas' disease without heart failure. Overall control of circulation appears to be compromised because patients did not maintain blood pressure under high levels of lower-body negative pressure.

Blood pressure responses to LBNP in nontrained and trained hypertensive rats

To study the influences of 16 wk of endurance training on the reflex regulation of resting blood pressure, nontrained (NT) and trained (T) female hypertensive rats (SHR) were subjected to conditions of lower body negative pressure (LBNP). Measurements of muscle cytochrome oxidase activity and run time to exhaustion indicated that the animals were endurance trained. The rats (NT = 6, T = 7) were tranquilized with 300-600 micrograms.kg-1 diazepam (IV) before heart rates and blood pressures were measured over a range of 2.5-10.0 mm Hg of negative pressure. When subjected to conditions of LBNP, the reflex tachycardia of the T group was greater than the NT at the lower (-2.5 and -5.0 mm Hg) negative pressures. Although arterial pressure declines were similar in both groups, the T group experienced significantly less of a decline in central venous pressure than the NT animals. When chlorisondamine was used as a ganglionic blocker (2.5 mg.kg-1, IV), the fall in CVP at 10 mm Hg negative pressure was greater for the NT group while the fall in the initial systemic arterial pressure was more for the T group. From these results we concluded that training had altered the interaction between cardiopulmonary and arterial baroreflexes in these hypertensive rats and a nonneural component had been altered such as cardiac function.

Pr VECPs related to ciliary perfusion pressure in primary open angle glaucoma. A study using contact lenses to compensate for refraction changes during artificially raised IOP.

Pr VECP studies in glaucoma patients with the IOP raised artificially by the suction cup method have recently been performed by several authors, who arrived at different results. The reason for those differences may be the changes employed. The refraction changes depend on the shape of the suction cup and the height of the artificial IOP raise. By using contact lenses and a suitably shaped suction cup refraction changes could be compensated for. Studies of the pr VECP with suction cup IOP elevation and simultaneous compensation for refraction changes by applying contact lenses were made on 17 patients with primary open angle glaucoma and 21 healthy volunteers. In healthy subjects pr VECP amplitudes were found unaltered or even slightly increased until 120 mmHg of negative pressure were reached in the cup. Beyond that range they dropped. Latencies remained unaltered over that range of negative pressures. Plotting the pr VECP amplitudes and latencies against ciliary perfusion pressure we obtained unaltered potentials over a range of ca. 20 mmHg, which we interpreted as autoregulative capacity. In the 17 glaucoma patients various degrees of impaired autoregulation were found corresponding to the progression of glaucoma damage.