Biological evaluation of a mechanical ventilator that operates by controlling an automated manual resuscitator. A descriptive study in swine

The Covid-19 outbreak challenged health systems around the world to design and implement cost-effective devices produced locally to meet the increased demand of mechanical ventilators worldwide. This study evaluates the physiological responses of healthy swine maintained under volume- or pressure-controlled mechanical ventilation by a mechanical ventilator implemented to bring life-support by automating a resuscitation bag and closely controlling ventilatory parameters. Physiological parameters were monitored in eight sedated animals (t₀) prior to inducing deep anaesthesia, and during the next six hours of mechanical ventilation (t₁-₇). Hemodynamic conditions were monitored periodically using a portable gas analyser machine (i.e. BEecf, carbonate, SaO₂, lactate, pH, PaO₂, PaCO₂) and a capnometer (i.e. ETCO₂). Electrocardiogram, echocardiography and lung ultrasonography were performed to detect in vivo alterations in these vital organs and pathological findings from necropsy were reported. The mechanical ventilator properly controlled physiological levels of blood biochemistry such as oxygenation parameters (PaO₂, PaCO₂, SaO₂, ETCO₂), acid-base equilibrium (pH, carbonate, BEecf), and perfusion of tissues (lactate levels). In addition, histopathological analysis showed no evidence of acute tissue damage in lung, heart, liver, kidney, or brain. All animals were able to breathe spontaneously after undergoing mechanical ventilation. These preclinical data, supports the biological safety of the medical device to move forward to further evaluation in clinical studies.

Acquired immune deficiency syndrome. A surgical perspective

Eighty-nine lymph node biopsies were performed on 82 patients with lymphadenopathy, immunosuppression, and possible acquired immune deficiency syndrome. The 21 patients with diagnoses of lymphoma or Kaposi's sarcoma were older, had more sexual contacts, and were sexually active for more years than patients with benign diagnoses. Cytomegalovirus and Epstein-Barr viral titers were elevated in both groups but were not significantly different in the benign and malignant groups. Skin flora were cultured from lymph node tissue in 24.7% of the patients. Two patients (2.5%) had wound infections with the same bacterium present in the lymph node culture, while 66 patients initially had two different benign pathologic patterns. Fifty-six patients had explosive follicular hyperplasia, and ten had follicular involution. Four of the patients with follicular involution and one with follicular hyperplasia subsequently had malignant tumors.

Generalized lymphadenopathy in homosexual men

The cases of 90 homosexual or bisexual men with generalized lymphadenopathy were studied by epidemiologic, clinical, pathologic, immunologic, and genetic methods. The patients ranged in age from 20 to 52 years and had histories of multiple sexually transmitted diseases and both recreational and prescription drug use. Histologically, their lymph nodes showed three patterns: explosive follicular hyperplasia; follicular involution with expansion of the paracortical area; and a mixed pattern of follicular hyperplasia and follicular involution in the same lymph node. The frequency of HLA-DR5 was significantly increased in these patients (p less than 0.005) compared with that in controls. All patients had impaired cell-mediated immunity. Opportunistic infections, lymphomas, or Kaposi's sarcoma subsequently developed in 15 patients who had had severe immune dysfunction for the previous 3 to 13 months. We suggest that generalized lymphadenopathy is part of the spectrum of a disorder manifested by acquired immunodeficiency, opportunistic infections, Kaposi's sarcoma, and malignant lymphomas.