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Biomedical subjects

Theodor Kolobow

Publications and source records attributed to Theodor Kolobow.

10 recordsLinked to original sources
PubMed2006

The Mucus Slurper: A novel tracheal tube that requires no tracheal tube suctioning. A preliminary report.

OBJECTIVE: The buildup of mucus within the endotracheal tube (ETT) progressively reduces its internal volume. We devised the Mucus Slurper as an integral part of the tracheal tube to aspirate all mucus automatically at its distal tip. DESIGN AND SETTING: In vitro, and in vivo studies in sheep at the National Institutes of Health, NHLBI, PCCMB. SUBJECTS: Six sheep, sedated, paralyzed, and mechanically ventilated INTERVENTIONS: We evaluated the Mucus Slurper in vitro, and we evaluated its efficacy and safety in three healthy sheep during 24 h on volume-controlled mechanical ventilation in comparison to three sheep managed with open tracheal tube suctioning. MEASUREMENTS AND RESULTS: In vitro: with the Mucus Slurper connected to a source of vacuum of 450-500 mmHg the total volume of a single suction lasting 0.1, 0.2, and 0.3 s was, respectively, 75.4 +/- 7.9, 114.5 +/- 4.6, and 143.4 +/- 8.7 ml; with the measured vacuum within the lumen of the Mucus Slurper ring of 37 cmH2O. In vivo: during mechanical ventilation we aspirated through the Mucus Slurper 13.4 +/- 3.3 cc mucus/24 h. During the course of single aspiration the Mucus Slurper never affected the level of applied PEEP. The tracheal tube was free of tracheal secretions in the Mucus Slurper group while thin secretions were found within the ETT in the control group. CONCLUSION: The Mucus Slurper is a novel device designed to keep the tracheal tube and proximal trachea free of mucus. In studies in sheep lasting 24 h the Mucus Slurper was safe and prevented all mucus accumulation within the ETT.

Animals↗
PubMed2006

Antibacterial-coated tracheal tubes cleaned with the Mucus Shaver : a novel method to retain long-term bactericidal activity of coated tracheal tubes.

OBJECTIVE: To assess the long-term benefit from antibacterial coatings of the tracheal tube (ETT), and to keep clean the lumen of the ETT. DESIGN: Experimental animal study. SETTING: USA National Institutes of Health. SUBJECTS: Twelve sheep. INTERVENTIONS: Twelve ETTs were internally dip-coated with a silver-sulfadiazine in polyurethane. We developed a concentric inflatable silicone rubber "razor", the Mucus Shaver (MS), to shave the ETT lumen free of mucus. In a single pass, we cleaned all mucus from the internal surface of the ETT. CONTROL GROUP: Five intubated sheep were mechanically ventilated for 72 h. The ETT was suctioned every 6 h. STUDY GROUP: Six sheep were intubated and mechanically ventilated for 72 h. The ETT was suctioned and cleaned with the MS every 6 h. An additional sheep was intubated and mechanically ventilated for 168 h. Bacteriologic studies and scanning electron microscopy were performed to assess bacterial colonization and thickness of secretions on the internal surface of the ETT. MEASUREMENTS AND MAIN RESULTS: In the control group, the ETT was always heavily colonized: median debris thickness was 380 microm, range 270-550 microm. In the study group, there was no colonization and no secretions in the ETT, except for three ETT that were colonized solely at the very tip. CONCLUSIONS: Silver-based coating of ETT cleaned with the MS every 6 h significantly reduces accumulation of mucus/secretion and bacterial growth within the ETT following 72 h of mechanical ventilation.

Animals↗
PubMed2004

Endotracheal tubes coated with antiseptics decrease bacterial colonization of the ventilator circuits, lungs, and endotracheal tube.

BACKGROUND: Formation of a bacterial biofilm within the endotracheal tube (ETT) after tracheal intubation is rapid and represents a ready source of lung bacterial colonization. The authors investigated bacterial colonization of the ventilator circuit, the ETT, and the lungs when the ETT was coated with silver-sulfadiazine and chlorhexidine in polyurethane, using no bacterial/viral filter attached to the ETT. METHODS: Sixteen sheep were randomized into two groups. Eight sheep were intubated with a standard ETT (control group), and eight were intubated with a coated ETT (study group). Animals were mechanically ventilated for 24 h. At autopsy, the authors sampled the trachea, bronchi, lobar parenchyma, and ETT for quantitative bacterial cultures. Qualitative bacterial cultures were obtained from the filter, humidifier, inspiratory and expiratory lines, and water trap. ETTs were analyzed with light microscopy, scanning electron microscopy, and laser scanning confocal microscopy. RESULTS: In the control group, all eight ETTs were heavily colonized (10(5)-10(8) colony-forming units [cfu]/g), forming a thick biofilm. The ventilator circuit was always colonized. Pathogenic bacteria colonized the trachea and the lungs in five of eight sheep (up to 10(9) cfu/g). In the study group, seven of eight ETTs and their ventilator circuits showed no growth, with absence of a biofilm; one ETT and the respective ventilator circuit showed low bacterial growth (10(3)-10(4) cfu/g). The trachea was colonized in three sheep, although lungs and bronchi showed no bacterial growth, except for one bronchus in one sheep. CONCLUSIONS: Coated ETTs induced a nonsignificant reduction of the tracheal colonization, eliminated (seven of eight) or reduced (one of eight) bacterial colonization of the ETT and ventilator circuits, and prevented lung bacterial colonization.

Animals↗
PubMed2004

Evaluation of continuous aspiration of subglottic secretion in an in vivo study.

OBJECTIVE: Continuous aspiration of subglottic secretions (CASS) is believed to lower the incidence of ventilator-associated pneumonia. Animal studies to establish safety and efficacy of CASS have not been conducted. DESIGN: Prospective randomized animal study. SETTING: Animal-research facility at the U.S. National Institutes of Health. SUBJECTS: Twenty-two sheep. INTERVENTIONS: Sheep were randomized into three groups. In group C (control), eight sheep were kept prone, intubated with a standard endotracheal tube (ETT), and mechanically ventilated for 72 hrs with head and ETT elevated at an angle of 30 degrees. In group CASS-HU (CASS, head up), seven sheep were managed as group C and intubated with a Hi-Lo Evac, Mallinckrodt ETT (CASS suction kept at < or =20 mm Hg). In group CASS-HD (CASS, head down), seven sheep were kept prone with CASS, and the ETT and trachea were horizontal to promote spontaneous drainage of mucus from the ETT. MEASUREMENTS AND RESULTS: The lower respiratory tract in the CASS-HU group was heavily colonized in all seven sheep (median 4.6 x 10(9), range, 1.5 x 10(8) to 7.9 x 10(9) colony-forming units/g), with a reduction of lung bacterial colonization compared with the C group (p = .05). In group CASS-HD, the lower respiratory tract was not colonized in six of seven sheep. One sheep showed low levels of bacterial growth (median, 0; range, 0-2.2 x 10(5)). At autopsy, in all 14 sheep with CASS, we found tracheal mucosal injury of different degrees of severity at the level of the suction port of the ETT. CONCLUSIONS: In group CASS-HU, regardless of finding a marginal decrease of the bacterial colonization of the lower airways, there was pervasive trachea-bronchial-lung bacterial colonization. Second, there was minimal, or absent, bacterial colonization when the orientation of the CASS ETT was at, or just below, horizontal. Third, there was widespread injury to tracheal mucosa/submucosa from the use of CASS. Note that results of studies conducted in an animal model are always difficult to extrapolate to the clinical practice due to anatomical and functional differences.

Animals↗
PubMed2004

Ultrathin-wall, two-stage, twin endotracheal tube: a tracheal tube with minimal resistance and minimal dead space for use in newborn and infant patients.

OBJECTIVE: To design and fabricate crush-proof polyurethane tracheal tubes for the newborn with the lowest resistance, least dead space, and thinnest wall. DESIGN: Test and evaluation of a novel, low-resistance, and low-dead-space tracheal tube for newborns. SETTING: National Institutes of Health Research Laboratory. INTERVENTIONS: The short orotracheal portion of the tracheal tube was fabricated of polyurethane, reinforced with flat nickel-titanium shape-memory alloy (Nitinol) to render the tube crush-proof, of a wall thickness about one half of a standard tracheal tube. To the oral part of the tracheal tube, which is the sole dead-space, we attached a Y piece. We connected to one arm of the Y a nonreinforced (inspiratory) tube of larger internal diameter, and a similar tube (expiratory) to the other. MEASUREMENTS AND RESULTS: The computed air flow resistance, as derived from the pressure/flow curves, is about one half to one third the resistance of a comparable standard tracheal tube at flow rates up to 8 L/min, with a tubing, connector, and adapter dead space three to seven times smaller, depending on the tracheal tube connector piece, the ventilator tube connector piece, and size of the tracheal tube. CONCLUSIONS: The novel tracheal tube design has a resistance to gas flow one half to one third that of a standard tracheal tube and a dead-space volume three to seven times lower, including tubing and connector dead space. In addition, it offers a means for potential accurate, continuous online monitoring of expiratory oxygen and Co(2) concentration and gas flow, in both the inspiratory and the expiratory lines, without contributing to dead-space ventilation or gas flow resistance.

Alloys↗
PubMed2003

Lethal systemic capillary leak syndrome associated with severe ventilator-induced lung injury: an experimental study.

OBJECTIVE: We report the evolution of severe ventilator-induced lung injury associated with lethal systemic capillary leak syndrome, when sheep were ventilated at a peak inspiratory pressure of 50 cm H2O, at a respiratory rate of 8 breaths.min, with an inspiratory time of 2.5 secs. DESIGN: A prospective laboratory animal study. SETTING: Experimental animal research laboratory. SUBJECTS: Mixed breed sheep. INTERVENTIONS: Sheep were anesthetized, paralyzed, and mechanically ventilated. MEASUREMENTS AND MAIN RESULTS: This sheep model was characterized by a rapidly evolving massive anasarca, hemoconcentration, cardiac dysfunction, multiple system organ failure, and severe ventilator-induced lung injury. Cardiovascular changes and profound hemoconcentration developed within 6 hrs from the start of mechanical ventilation, along with a major decline in pulmonary compliance and deterioration in arterial blood gases. When total static lung compliance decreased to 0.15 mL (cm H2O)(-1) x kg(-1) (7-30 hrs), the sheep were randomized to two groups. Group I received high (recruitive) positive end-expiratory pressure (9-20 cm H2O), adjusted as needed; group II received low (supportive) positive end-expiratory pressure (2-6 cm H2O). Sheep in both groups progressively deteriorated and died with cardiocirculatory failure and multiple system organ failure within 12-24 hrs from start of treatment. CONCLUSIONS: This model of lethal systemic capillary leak syndrome with multiple system organ failure differs greatly from our previous sheep model of acute ventilator-induced lung injury in which sheep were ventilated with a peak inspiratory pressure of 50 cm H2O, a respiratory rate of 4 breaths x min(-1), and an inspiratory time of 1.35 secs, without inducing capillary leak syndrome. The mere change of respiratory rate from 4 to 8 breaths x min(-1), with a near doubling of the inspiratory time to 2.5 secs, although maintaining eucapnia, resulted in lethal systemic capillary leak syndrome and multiple system organ failure with both gross and microscopic pathology of lungs greatly different from our previous model of mechanical ventilation-induced acute respiratory distress syndrome.

Animals↗
PubMed2003

Glottic-modulated lung ventilation during continuous transtracheal gas insufflation: an experimental study.

We investigated a new method of pulmonary ventilation that included a minitracheostomy, a reverse thrust catheter to deliver continuous flow of gas to the carina, and a threshold valve to avoid lung overinflation. In six lightly sedated healthy sheep, at a continuous flow of 5, 10, or 15 L/min and a threshold valve of 5, 10, 15, or 20 cm H(2)O, we observed a novel respiratory pattern that was characterized either by active lung inflation followed by passive and prolonged inspiratory hold (mixed pattern) or by an absence of all active inspiratory effort and only passive inflation of the lungs (passive pattern). We correlated airway pressure changes with direct visualization of the glottic opening through a fiberoptic bronchoscope. We measured airway pressures at the level of the carina, the subglottic level, and in the pleural space, and respiratory events were monitored through inductive plethysmography. An increase in continuous flow, threshold valve, or both resulted in 1) an increase in glottic breathing; 2) a decrease in respiratory rate, with a decrease in inspiratory pleural pressure excursion; or 3) an increased inspiratory/expiratory ratio and mean airway pressure. During transtracheal gas insufflation, as in this study, a novel respiratory pattern evolved that was modulated by the glottis, accompanied by a decreased effort of breathing; coughing and swallowing remained, and vocalization remained unimpaired.

Airway Resistance↗