Resuscitation of severe thermal injury with hypertonic saline dextran: effects on peripheral and visceral edema in sheep.

Background: Edema of tissue not directly injured by heat is a common complication after resuscitation of burn shock. Hypertonic 7.5% NaCl 6% dextran (HSD) infusion reduces early fluid requirements in burn shock, but the effects of HSD on peripheral and visceral tissue edema are not well-defined.

beta-adrenergic desensitization after burn excision not affected by the use of epinephrine to limit blood loss.

Background: Burn patients have impaired myocardial function and decreased beta-adrenergic responsiveness. Further beta-adrenergic dysfunction from systemic absorption of topically administered epinephrine that is given to limit blood loss during burn excision could affect perioperative management. The authors evaluated the effect of topical epinephrine administration to patients during burn excision on the lymphocytic beta-adrenergic response.

New clinically relevant sheep model of severe respiratory failure secondary to combined smoke inhalation/cutaneous flame burn injury.

Objectives: To develop a predictable, dose-dependent, clinically relevant model of severe respiratory failure associated with a 40% total body surface area, full-thickness (third-degree) cutaneous flame burn and smoke inhalation injury in adult sheep.

Design: Model development.

Setting: Research laboratory.

Reduced ventilator pressure and improved P/F ratio during percutaneous arteriovenous carbon dioxide removal for severe respiratory failure.

Objective: To evaluate the effect of percutaneous arteriovenous carbon dioxide removal (AVCO2R) on ventilator pressures and P/F ratio in a clinically relevant large-animal model of severe respiratory failure.

Summary Background Data: AVCO2R was developed as a simple arteriovenous shunt with a commercially available low-resistance gas exchange device of sufficient surface area for near-total CO2 removal. With an AV shunt 10% to 15% of cardiac output, AVCO2R allows a reduction in ventilator airway pressures without hypercapnia or the complex circuitry and monitoring required for conventional ECMO.

Percutaneous extracorporeal arteriovenous CO2 removal for severe respiratory failure.

Background: In previous animal studies, arteriovenous CO2 removal (AVCO2R) achieved significant reduction in ventilator pressures and improvement in the Pao2 to fraction of inspired oxygen ratio during severe respiratory failure. For our initial clinical experience, 5 patients were approved for treatment of severe respiratory failure and CO2 retention to evaluate the feasibility and safety of percutaneous AVCO2R.

Methods: Patients were anticoagulated with heparin (activated clotting time, 260 to 300 seconds), underwent percutaneous femoral cannulation (10F to 12F arterial and 12F to 15F venous catheters), and then were connected to a low-resistance, 2.

Selective inhibition of inducible nitric oxide synthase: effects on hemodynamics and regional blood flow in healthy and septic sheep.

Objectives: To investigate the effects of S-ethylisothiourea (S-EITU) on hemodynamics, oxygen transport, and regional blood flow in healthy and septic sheep.

Design: Prospective, randomized, controlled experimental study with repeated measures.

Setting: Investigational intensive care unit at a university medical center.

Reduction in mortality in pediatric patients with inhalation injury with aerosolized heparin/N-acetylcystine [correction of acetylcystine] therapy.

Smoke-inhalation injury causes a destruction of the ciliated epithelium that lines the tracheobronchial tree. Casts produced from these cells, polymorphonuclear leukocytes and mucus, can cause upper-airway obstruction, contributing to pulmonary failure. We have reported that a combination of aerosolized heparin and a mucolytic agent, N-acetylcystine [corrected], can ameliorate cast formation and reduce pulmonary failure secondary to smoke inhalation.

Altered systemic organ blood flow after combined injury with burn and smoke inhalation.

Systemic organ blood flow was longitudinally determined with fluorescent microspheres after severe thermal injury in unanesthetized sheep. After chronic instrumentation, 20 sheep were subjected to combined injury with 40% body surface area third-degree burn and 48 breaths of cotton smoke insufflation. During the next 72 h of the experimental period, all animals were resuscitated with Ringer's lactate following the Parkland formula.

Effect of reduced bronchial circulation on lung fluid flux after smoke inhalation in sheep.

We determined the effect of reduced bronchial blood flow on lung fluid flux through changes in lung lymph flow, lung wet weight-to-dry weight (wet/dry) ratios, and pulmonary microvascular reflection coefficient (sigma). In the first of two surgical procedures, Merino ewes (n = 21) were surgically prepared for chronic study. Five to seven days later, in a second operation, the bronchial artery of the injection group (n = 7) was ligated, and 4 ml of 70% ethanol were injected into the bronchial artery to cause sclerosis of the airway circulation.

Total arteriovenous CO2 removal: simplifying extracorporeal support for respiratory failure.

Background: To reduce the complexity, complications, and cost of conventional extracorporeal membrane oxygenation, we have developed a technique of simplified arteriovenous extracorporeal CO2 removal (AVCO2R) with a low-resistance membrane gas exchanger for total CO2 removal to provide lung rest in the setting of severe respiratory failure.

Methods: We initially used AVCO2R in healthy animals to quantify the gas exchange capabilities of the system and establish ventilator management protocols for the subsequent studies of AVCO2R in a large animal model of respiratory failure secondary to a severe smoke inhalation injury.

Results: In healthy sheep the maximum spontaneous arteriovenous flow ranged from 1,350 to 1,500 mL/min, whereas CO2 removal plateaued at a blood flow of approximately 1,000 mL/min in which 112 +/- 3 mL/min CO2 was removed, allowing an 84% reduction in the minute ventilation of from 6.

Correction of blood pH attenuates changes in hemodynamics and organ blood flow during permissive hypercapnia.

Objectives: To determine whether changes in cardiac output, regional blood flow, and intracranial pressure during permissive hypercapnia are blood pH-dependent and can be attenuated by correction of intravascular acidemia.

Design: Prospective, controlled study.

Setting: Research laboratory.

Smoke inhalation causes a delayed increase in airway blood flow to primarily uninjured lung areas.

Objective: Single lung inhalation injury causes tissue damage to the contralateral lung. We therefore examined airway blood flow after smoke inhalation in chronic instrumented sheep to get further information about the underlying pathophysiology.

Design/patients: The right lung and lower trachea of 5 animals were smoke-exposed, while their left lung was air-insufflated using a split ventilation technique.

Development and current status of a new intracorporeal membrane oxygenator (IVOX).

The IVOX (intravascular oxygenator) is an intracorporeal, hollow-fibre membrane oxygenator and carbon dioxide (CO 2) removal device. The IVOX is surgically placed into the vena cava via a femoral or jugular venotomy. Oxygen (O 2) is pulled through the hollow fibres by a vacuum pump controlled by a flow meter.

Selective permeability changes in the lungs and airways of sheep after toxic smoke inhalation.

The effect of toxic smoke inhalation on selective microvascular sieving of macro-molecules and lymph protein flux was assessed in adult sheep to determine whether the time course of microvascular dysfunction differs between the lung and trachea. Protein flux across the lung increased sixfold 48 h after inhalation of the products of incomplete cotton combustion, whereas tracheal protein flux increased fivefold 8 h after exposure and returned to near base line 48 h after exposure. The lung and trachea selectively retained some sieving to three different protein macromolecules with molecular radii of 36, 54, and 123 A.