Computed tomography assessment of lung volume changes after bronchial valve treatment.

The aim of the present study was to correlate clinical outcome measures following treatment with bronchial valves with regional lung volume. Computed tomography (CT) scan data from 57 subjects with severe emphysema were obtained from nine North American clinical trial sites. IBV(R) Valves (Spiration, Inc., Redmond, WA, USA) were placed to occlude segmental and subsegmental bronchi in right and left upper lobes using a flexible bronchoscope. Subjects completed a St George's Respiratory Questionnaire (SGRQ), pulmonary function test (PFT) and exercise capacity test. CT scans were analysed at baseline and at 1, 3 or 6 months after treatment to measure total and lobar lung density, volume and mass. Total lung volumes measured using CT were strongly correlated with PFT and did not change with treatment. However, the treated upper lobes significantly decreased in volume in 88% of the observations, by mean+/-sd 335+/-444 mL, or a decrease of 10.2% in the 6 month data. The untreated lobes had an 11.6% increase in volume. Changes in regional lung volume were associated with clinically meaningful improvements in SGRQ (-8.95+/-16.22), but not clinically meaningful PFT changes. The significant health status improvements reported by subjects following bilateral bronchial valve treatment are associated with regional lung volume changes and interlobar shift measured using computed tomography.

Comparative anatomy and histochemistry of human and canine latissimus dorsi muscle.

Gross and histologic studies of human and canine latissimus dorsi muscle were carried out to identify anatomic and histochemical properties that may be relevant to its use as a resource muscle, particularly for heart reconstruction. In both human and canine latissimus dorsi, three distinct muscle segments were observed, differing in direction of fibers, fiber characteristics, thickness, and blood supply. The entire canine latissimus dorsi could also be separated into superficial and deep layers, whereas only the anterolateral segment of human latissimus dorsi was separated further by the neurovascular bundle. Histochemical studies suggested significant differences between the ratios of fast to slow fibers in the superior and anterolateral segments of human muscle. Variation in size, weight, and shape within and between subjects demonstrates a need for careful evaluation of the potential resource muscle.

The significance of colloid osmotic pressure during induced hypothermia.

Colloid osmotic pressure (COP) during hypothermia with and without total circulatory arrest was evaluated in 20 adult mongrel dogs (average body weight = 18.6 kg). All animals were surface-cooled to 20 degrees C (rectal temperature) under halothane-diethyl ether azeotrope anesthesia and divided into 4 equal groups. In Groups I (non-arrest) and II (60 minute-arrest) 10% low molecular weight dextran (LMWD; 1 gm/kg = 10 ml/kg) was administered during cooling. Physiological saline (10 ml/kg) was given in Groups III (non-arrest) and IV (60 minute-arrest) during cooling. COP in LMWD groups increased significantly during cooling and was consistently higher than it was in the saline groups during rewarming. There were no significant differences in heart rate (HR), mean arterial pressure (MAP), central venous (CVP) and pulmonary artery wedge pressures (PAW) between the 4 groups during cooling. The increase in hematocrit (Hct) in animals that received saline was significant at the end of cooling and during rewarming. Hct was not significantly changed in Group I throughout the procedure, whereas in Group II (60 minute-arrest) it increased significantly during rewarming despite the administration of LMWD. Rewarming time in Group II was significantly shorter than in Group IV (144.2 +/- 9.6 min vs 193.2 +/- 32.6 min, respectively). We conclude that the administration of LMWD effectively reduces hemoconcentration and is also beneficial for maintaining better peripheral circulation.

Whole body protection during three hours of total circulatory arrest: an experimental study.

Survival following 3 hr of total circulatory arrest under profound hypothermic conditions was explored in 19 adult mongrel dogs. Thermoregulatory management included combined surface/perfusion hypothermia and azeotrope anesthesia in 95% O2/5% CO2. All animals were resuscitated and survived for at least 12 hr. During the last seven trials (Group II) the following principles were applied: uniform whole-body cooling where differences between rectal, esophageal, and pharyngeal temperatures averaged less than 1 degree C, induction of circulatory arrest at approximately 3 degrees C, constant lung inflation (10-12 cm H2O between 20 degrees C cooling and 20 degrees C rewarming, including the 3-hr arrest period) and ventilation assistance with positive end-expiratory pressure (4 cm H2O) after 20 degrees C rewarming, intraoperative maintenance of colloid osmotic pressure (COP) above 11 mm Hg, replacement of the cooling perfusate with a colloid-rich rewarming prime (COP = 15 mm Hg) and restoration of hemostasis with fresh whole blood transfusions. The application of these principles resulted in the long-term survival of five animals with four survivors displaying no clinically detectable neurological abnormalities. However, two animals developed optic impairment and one animal died from intusseption on the fourth postoperative day. Despite the improved results, it should also be noted that during pilot (Group I) studies (from which the aforementioned principles were derived) fatalities from complications attributed to systemic edema, central nervous system, or pulmonary or coagulation dysfunctions occurred in 9 out of 12 trials. We conclude that whole body protection following 3 hr of total circulatory arrest at a uniform temperature less than 5 degrees C can be successfully accomplished.

Patch closure of aortic annulus mycotic aneurysms.

Twenty-three patients with bacterial endocarditis and mycotic aneurysms of the aortic annulus were treated between 1978 and 1985. There were 18 men and 5 women ranging from 24 to 72 years old. All patients had congestive heart failure and positive blood cultures as a complication of the endocarditis and were in New York Heart Association (NYHA) Functional Class III or IV. The aneurysm complicated late prosthetic valve endocarditis in 7 patients and native valve endocarditis in 16. The most common infecting organisms were streptococci (12 patients) and staphylococci (7 patients). The noncoronary sinus was the most frequent site for aneurysm formation. Following debridement of the abscess cavity, the orifice of the aneurysm was closed with a patch of Dacron in 20 patients and autologous pericardium in 3. A prosthetic valve (18 bioprosthetic and 5 mechanical) was secured to the noninfected portion of the native annulus and to the patch at the level of annulus. There were 3 deaths, 1 perioperative and 2 late, each without evidence of residual infection or aortic insufficiency. There are 20 late survivors (87%). After a mean follow-up of 1 year, all patients are in NYHA Functional Class I. Patch closure of mycotic aneurysms involving the aortic annulus permits aggressive debridement of the abscess cavity and affords closure of the orifice without tension. The prosthetic valve can be seated at the level of the native annulus, thus avoiding complicated reconstructive procedures of the aortic root and coronary arteries. This technique is an effective alternative in selected cases of mycotic aneurysms involving the aortic annulus.

Simplified technique for pericardial patch of the right ventricular outflow tract.

Pericardial patching to enlarge the right ventricular outflow tract is often required in congenital cardiac surgery in lesions such as tetralogy of Fallot, pulmonary atresia, pulmonary stenosis, and pulmonary artery repair following removal of a palliative pulmonary artery band. A method of simplifying the attachment of the pericardial patch onto the right ventricular outflow tract is described.

Blood anesthetic levels during surface-induced deep hypothermia under halothane-diethyl ether azeotrope anesthesia.

Blood anesthetic concentration and clinical indicators related to anesthetic management during surface-induced deep hypothermia were determined in seven adult mongrel dogs. The azeotrope of halothane and diethyl ether was assayed by gas chromatography. Blood concentration of halothane ranged from a pre-cooling control of 0.74 vol % to 0.11 vol % at 20 degrees C rewarming; ether ranged from 0.06 vol % at 20 degrees C rewarming to 0.22 vol % at 35 degrees C rewarming. Administration of anesthetic was reduced during cooling because of the spontaneous decrease in mean arterial pressure and heart rate. After elective circulatory arrest was induced, anesthetic was not required until after cardiac resuscitation at about 22 degrees C rewarming. Initial clinical signs indicating a need to increase administration of anesthetic included spontaneous respiration and an increase in mean arterial pressure. Blood azeotrope concentration was significantly lower during rewarming than at comparable temperatures during cooling. We conclude that blood concentration of halothane and ether changes as a function of body temperature and that anesthetic demand may be diminished following total circulatory arrest.

Autotransplantation of skeletal muscle into myocardium.

In a series of 15 studies in dogs, sternocleidomastoid muscle was used to replace deficits created in left ventricular myocardium and sternohyoid muscle was used to replace portions of right myocardial wall. The five right ventricular autotransplants resulted in a 100% surgical success rate, with animals electively killed between 3 and 55 weeks after surgery. In 10 left ventricular studies excision of areas varying from 12 X 46 mm to 30 X 60 mm and incisions of from 40 mm to 70 mm in length were performed. Left ventricular studies resulted in a 60% surgical success rate, with clinically healthy animals being killed for study between 2 weeks and 50 weeks after surgery. Animals surviving the critical surgical recovery period showed no loss of weight or changes in activity. Gross findings at autopsy confirmed the viability of the skeletal muscle transplants. Borders were well healed and the grafted tissue was pliable. Histologic studies suggest that revascularization of skeletal muscle occurred from the myocardial side, and that there were healthy myocardial and skeletal muscle fibers at the junction, with evidence of regeneration.

The importance of appropriate concentrations of inspired carbon dioxide on induced hypothermia under halothane-ether azeotrope anesthesia.

Thirty adult mongrel dogs were divided into 3 equal groups and studied to define the optimal PCO2 level with azeotrope (halothane-diethyl ether) anesthesia under surface hypothermia (Groups I, II and III = F1CO2 0%, 5% and 10%, respectively). All animals were cooled to 18-20 degrees C and were subjected to 30 (Group I) or 60 minutes (Groups II and III) of total circulatory arrest. Group I animals had frequent arrhythmic episodes during cooling and postoperative motor disturbances occurred in 80% despite only 30 minutes of circulatory arrest. By contrast Group II animals were less arrhythmic during cooling; were easily resuscitated following 60 minutes of arrest and only 30% developed moderate reversible motor disturbances postoperatively. Hemodynamics were similar between Groups II and III during cooling but resuscitation using an F1CO2 of 10% (Group III) was extremely difficult and required massive cardiotonic support throughout rewarming. Furthermore, two dogs in Group III died within the first two postoperative days. However, none of the 8 survivors displayed neurological abnormalities. On balance, a ventilatory regimen utilizing 5% CO2 during surface-induced hypothermia under azeotrope anesthesia resulted in optimum intraoperative management and a satisfactory postoperative course and although some CNS disturbance (high-stepping gait) was noted, all animals recovered completely.

Prolongation of the safe interval of hypothermic circulatory arrest: 90 minutes.

Twenty-nine adult mongrel dogs were subjected to profound hypothermia and 90 minutes of total circulatory arrest. Pure surface (Group I) hypothermia and combined surface/perfusion techniques with bubble (Group II) and membrane (Group III) oxygenator systems were employed. Circulation was arrested at average esophageal temperatures of 18.4 degrees, 11.9 degrees and 8.5 degrees C in Groups I, II and III, respectively. Three animals in Group I failed to resuscitate. All survivors in the pure surface series developed postoperative gait (hypermetria) disturbances. One intraoperative death occurred in Group II and four of eight dogs arrested at esophageal temperatures above 10 degrees C but less than 15 degrees C developed motor disturbances during a three week neurologic evaluation period. Animals arrested below 10 degrees C (esophageal) did not display postoperative neurological abnormalities. Three dogs in Group III died from a hemorrhagic diathesis of uncertain etiology. None of the survivors (5) that were cooled and arrested below esophageal temperatures of 10 degrees C developed motor or sensory disturbances. We conclude that in the canine model the central nervous system can be protected for 90 minutes of total circulatory arrest at esophageal temperatures less than 10 degrees C.

Circulatory dynamics during surface-induced hypothermia under halothane-ether azeotrope anesthesia.

Circulatory dynamics during surface- induced deep hypothermia using the halothane-diethyl ether azeotrope in 100% oxygen (O2) without circulatory arrest and 95% O2 and 5% carbon dioxide (CO2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO2 than in animals given 100% O2 during cooling. Cardiac output in the 5% CO2 groups increased until 30 degrees C cooling and then gradually decreased to 29% of control at 20 degrees C. Cardiac output in the 100% O2 group progressively decreased to 16% of control at 20 degrees C cooling and was 51 to 77% of the output in the 5% CO2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O2 and had only doubled in the 5% CO2 groups at 20 degrees C during cooling. Hemodynamic variables in animals given 5% CO2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane-diethyl ether azeotrope in 95% O2 and 5% CO2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.

Boerhaave syndrome. Successful conservative management in three patients with late presentation.

Three patients with Boerhaave syndrome were successfully managed with nonoperative treatment. The diagnosis was delayed 5 days in one patient and 10 days in the other two. None of the patients appeared septic. Their conditions had been misdiagnosed as myocardial infarction, pneumonia and pulmonary embolism. Treatment consisted of intravenous hyperalimentation and administration of antacids and antibiotics. Cimetidine was also used in one patient. Two patients were discharged 14 days after diagnosis and the third on the 20th hospital day. Follow-up barium swallows showed complete healing in 2 months in all three patients. Conservative management of spontaneous esophageal perforation is feasible when (1) the perforation is already 5 days old, (2) there are no signs of severe sepsis, (3) esophageal barium study shows a wide-mouthed cavity draining freely back into the esophagus, and (4) the pleural space is not contaminated. When the diagnosis is made promptly, surgical therapy remains the treatment of choice, and patients managed conservatively who show signs of sepsis should be operated on without hesitation. Follow-up esophageal evaluation should be performed to confirm complete healing and to evaluate underlying disease.

Determination of cardiac output by thermodilution during hypothermia.

The thermodilution method for estimating cardiac output was compared with the electromagnetic flowmeter technique in 10 mongrel dogs at normothermia and during surface-induced deep hypothermia. Thermodilution curves obtained during cooling or rewarming must be corrected for the baseline drift caused by changing core temperature. At normothermia, the correlation coefficient between the two methods was 0.96 and the reproducibility of the thermodilution technique was 5 percent. Comparable correlation was present during hypothermia. Curves corrected for baseline drift resulted in significantly different output values from those derived from uncorrected curves (p < 0.05). The thermodilution method is valid at low body temperatures. Clinical confirmation of these results, particularly during open heart surgery in infants, is warranted.

Improved anesthesia for deep surface-induced hypothermia: the halothane-diethyl ether azeotrope.

The halothane-diethyl ether azeotrope was evaluated in dogs as the anesthetic agent for deep surface hypothermia with total circulatory arrest for open-heart operation. All 10 animals given azeotrope in 100% oxygen (O2) experienced atrial arrhythmias during cooling, and 1 had ventricular fibrillation prior to the completion of cooling at 18 degrees to 20 degrees C. After only 30 minutes' arrest, 8 of the 10 dogs had postoperative motor disturbances. Administering the azeotrope in 95% O2 and 5% carbon dioxide (CO2) yielded markedly improved results characterized by a rapid, smooth cooling course, easy resuscitation following circulatory arrest, and rapid rewarming, and 3 out of 10 dogs experienced mild motor disturbance after 60 minutes of circulatory arrest. This method, when compared with our standard method of ether in 100% O2, resulted in reduced blood lactates and a striking improvement in clinical status on the first postoperative morning. In limited clinical trials, infants undergoing repair of congenital cardiac defects have done well and responded as expected based on the laboratory experience. Since the results with the azeotrope in 95% O2 and 5% CO2 were at least as good as, and in several instances better than, those with the standard method employing either, the nonexplosive characteristic of the azeotrope warrants continued evaluation of this agent.

Use of athrombogenic tubing for perfusion rewarming following surface-induced deep hypothermia.

A method of heparinless, oxygenatorless, left heart bypass perfusion rewarming following surface hypothermia, with the use of a closed circuit with 130 ml. prime volume including heat exchanger, has been devised. The use of polyurethane-polyvinyl-graphite (PPG)-coated tubing has previously been reported. In this text, the use of an athrombogenic coating with cetyl-pyridinium chloride (CPC) as a regional heparin carrier was studied in dogs, comparing groups with PPG tubing and total systemic heparinization or plain polyvinyl tubing without systemic heparinization. Heparin compounded in the CPC coating eluted into the blood and caused mild transient whole-body heparinization during rewarming from 20 degrees to 25 degrees C., as evidenced by prolongation of the thrombin time. Alterations of hematologic parameters in all three groups were similar to those during surface rewarming except for those affected by heparinization. The left heart bypass method was found useful for hypothermic open-heart surgery when utilized with an athrombogenic surface coating or total body heparinization. It was concluded that the CPC coating is superior to the PPG coating since no cracking surface develops, it is translucent, and it provides a more effective athrombogenic surface.