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Biomedical subjects

T Kolobow

Publications and source records attributed to T Kolobow.

106 records · Page 6Linked to original sources
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Cardiopulmonary bypass through peripheral cannulation with percutaneous decompression of the left heart in a model of severe myocardial failure.

Prolonged closed chest cardiopulmonary bypass for severe total biventricular myocardial dysfunction requires invasive decompression of the left heart. The authors have developed an elongated helical coil that is permanently attached to the distal 8-10 cm of a flow directed Swan-Ganz catheter. When properly positioned, the helical coil kept the pulmonary artery (PA) and the tricuspid valves open, and allowed closed chest retrograde decompression of the left heart. The authors have evaluated the merits of closed chest cardiopulmonary bypass with decompression of the left heart in this manner in four sheep subjected to 30 min of warm global myocardial ischemia, along with induced ventricular fibrillation. All sheep developed severe global myocardial failure, with no left ventricular (LV) ejection. The authors have shown that pulmonary blood flow during cardiopulmonary bypass was reversed from the left heart, across the lungs, and into the right heart. The wedge pressure never exceeded 12 mmHg at any time, attesting to good decompression during periods of total ventricular failure, during partial recovery with some LV ejection, and after good recovery of LV function, followed by weaning from bypass after 44, 67, and 78 h of such support. One sheep could not be weaned from bypass, even after 5 days of CPBP. Lung function in all sheep remained unimpaired throughout, and there was no wound bleeding. The authors conclude that in this model of total myocardial failure, and while on closed chest CPBP, at all times and with all degrees of myocardial dysfunction, excellent LV decompression with the helical coil catheter was attained.

Animals↗
PubMedDate not supplied

Low-frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV-ECCO2R): an experimental study.

We describe a new form of mechanical pulmonary ventilation, low-frequency positive pressure ventilation with extracorporeal CO2 removal (LEPPV-ECCO2R). In a series of animal studies the rate of mechanical ventilation was 0.66, 1, 2, and 4 min-1 at a tidal volume of 3, 10, and 15 ml kg-1. We were able to maintain normal blood gases and normal lung volumes and lung mechanics even at the lowest ventilator rate with tidal volumes of 10 or 15 ml kg-1. Each experiment lasted 7 hours. Our data suggest a possible new dimension in the management of a difficult patient on mechanical pulmonary ventilation.

Animals↗
PubMedDate not supplied

Dispersion-casting thin and ultrathin fabric-reinforced silicone rubber membrane for use in the membrane lung.

Pinholes in thin silicone rubber membrane have previously been traced to undispersed silica filer aggregates within the silicone rubber. This was overcome by centrifuging the dispersion to remove the aggregates prior to membrane fabrication. Thin (less than 75 mu) and ultra-thin (less than 25 mum) membrane could then be dispersion-cast. To facilitate handling and to increase mixing of blood in the membrane lung, it is often desirable to reinforce the silicone rubber membrane with fabric. Unfortunately, this process frequently introduces pinholes of its own. We have found than pinhole-free fabric-reinforced silicone rubber membrane can consistently be produced by the double-layer casting technique. First, the dispersion is cast onto aluminum foil, solvent evaporated, and partially cured. A second layer is next cast on top of it, followed by fabric. After solvent evaporation, final cure is under nitrogen using organic peroxide catalysts. This technique has permitted us to consistently cast strong pinhole-free membranes as thin as 9 mu.

Humans↗
PubMedDate not supplied

Long-term closed chest partial and total cardiopulmonary bypass by peripheral cannulation for severe right and/or left ventricular failure, including ventricular fibrillation. The use of a percutaneous spring in the pulmonary artery position to decompress the left heart.

The authors report that total cardiopulmonary bypass (CPBP) for severe heart failure can be safely maintained for several days through peripheral cannulation alone. In two healthy sheep under general anesthesia, the authors cannulated the right external jugular vein and the right subclavian artery. A special spring was attached to a 7F Swan-Ganz catheter and positioned at the level of the pulmonary artery (PA) valve, rendering it partially incompetent. The extracorporeal circuit included a venous reservoir, a roller pump, a membrane lung, and a blood pulsator set at 25 beats/min. Ventricular fibrillation was induced with 110 VAC. Extracorporeal blood flow was raised to 100-120 ml/kg min. Mechanical pulmonary ventilation was changed to 5% CO2 in room air. During bypass, the wedge pressure (WP) averaged 9-13 mmHg, PA pressure 7-13 mmHg, and central venous pressure 1-9 mmHg. After 38 and 48 hr respectively the hearts were defibrillated with DC shock. There was total heart failure with no ejection from right or left. We continued with TCPBP. The right heart recovered after 1 and 3 hr respectively. After 7 and 5 hr, respectively, there was some aortic ejection. By 11 and 4 hr, respectively, the sheep were off bypass and on room air, with return to baseline cardiac function. Throughout the recovery the WP averaged 4-8 mmHg. At autopsy, all hearts were soft and normal in appearance. Histologic examination of the lungs and the heart was unremarkable. The authors conclude that the PA spring readily decompressed the LV. Ventilating lungs with 5% CO2 in air during CPBP sustained excellent lung function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

A new ultrathin-walled, non-kinking, low-resistance endotracheal tube for neonatal use: preliminary studies of a new no-pressure cuff.

Using a new technology, the authors fabricated a series of ultrathin-walled, non-kinking, wire-reinforced polyurethane endotracheal (ET) tubes for use in the newborn, with a wall thickness of 0.2 mm from the smallest to the largest ET tubes (one-stage tubes), as well as two-stage ET tubes, with the tracheal section of smaller diameter than the oropharyngeal section. The wire reinforcement consisted of 0.1-mm x 0.5-mm stainless steel 304 flat wire; to impart crush-proof features, some ET tubes were reinforced with Nitinol (nickel-titanium shape-memory alloy) wire. Circular layers of highly pliable polyurethane film ("gills"), 0.025 mm thick, in series, were then incorporated onto the distal sections of the ET tubes to reduce potential air leakage (no-pressure cuff). In-vitro pressure-flow measurements showed a sixfold-to-ninefold decrease in airflow resistance for the two-stage ET tubes, compared with standard tubes. For example, a two-stage ET tube of the new design with the outside diameter of a standard 2.5-mm ET tube has the airflow resistance of a hypothetical conventional 4.2-mm ET tube, while a straight ET tube with a similar thin wall and the same outside diameter throughout (one-stage ET tube) has the resistance of an imputed 3.2-mm standard ET tube, or a twofold-to-threefold decrease in air flow resistance. When tested in a 4-kg rabbit, the air leak of the 2.5-mm two-stage ET tube with "gills" and the outside diameter of a standard 2.5-mm ET tube was much less than that of a standard 2.5-mm ET tube, and was similar to the air leak found with a 4.0-mm ET tube of conventional design (without cuff). The authors conclude that the new ET tubes have a greatly reduced air flow resistance compared with conventional ET tubes; they provide enhanced sealing from possible air leaks; they are non-kinking and crush-resistant; and they are crush-proof when used with Nitinol wire reinforcement.

Animals↗
PubMedDate not supplied

Rescue from pediatric ECMO with prolonged hybrid intratracheal pulmonary ventilation. A technique for reducing dead space ventilation and preventing ventilator induced lung injury.

Hybrid intratracheal pulmonary ventilation (h-ITPV) is a continuous flow ventilatory technique that uses a "reverse thruster" catheter to redirect the flow of gas away from the carina. We report here the use of h-ITPV in a pediatric patient with acute sickle cell chest syndrome who required venoarterial ECMO support because of refractory hypoxemic respiratory failure. Her ECMO course was complicated by air leaks, coagulopathy, cardiac tamponade, and necrotizing tracheobronchitis. She could be weaned from ECMO only by maintaining high pressure conventional ventilatory support. To prevent ventilator induced barotrauma, we initiated h-ITPV and weaned her from ECMO bypass. After 12 days of h-ITPV, with tidal volumes of 2-3 ml/kg at carinal peak inspiratory pressures of 25-30 cm H2O, the air leaks ceased and h-ITPV was discontinued. Dead space ventilation fraction (VD/VT) as low as 0.29 was achieved with this technique. Post-h-ITPV bronchoscopy displayed a dramatic resolution of the necrotizing tracheobronchitis. The patient survived and was discharged from the hospital. We conclude that the use of hybrid ITPV may facilitate weaning from ECMO to low pressure conventional ventilation and prevent the development of pulmonary barotrauma.

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