[Density-mask spiral computed tomography in patients who are candidates for a lung-volume-reduction intervention: a preliminary study]

PURPOSE

To investigate the usefulness of helical CT with multiplanar reconstructions and density mask in emphysematous patients candidate for lung volume reduction surgery (LVRS), in order to assess the feasibility of surgery and for surgical planning.

MATERIAL AND METHODS

Twenty emphysematous patients (5 women and 15 men; age range: 55-67 years, mean: 61) candidate for LVRS were submitted to isotope perfusion scanning, chest radiography during maximal inspiration and expiration and Helical CT with the low volume contrast technique, multiplanar reconstructions and density mask.

RESULTS

Only 8 of the 20 patients examined were submitted to LVRS. They had irregular distribution of emphysema at isotope perfusion scanning and density mask CT. Surgery consisted in an atypical resection of the upper lobe portions which appeared most damage with both techniques. Six of the remaining 12 nonsurgical patients were excluded because of homogeneous distribution of emphysema at both CT and perfusion scanning, which was incompatible with surgery. Lung transplant was considered for 4 of these patients, but only 2 of them actually received it. Three patients were excluded from LVRS because of excessive diaphragm excursion during expiration at chest radiography and of multiple confluent areas of emphysema in both lung at CT and perfusion scanning. One patient with a large area of emphysema in the right upper lobe at CT and perfusion scanning was excluded due to associated severe interstitial disease. Another patient with emphysema mainly involving the lower lobes, as clearly depicted with both techniques, was excluded because the emphysema was secondary to alpha 1-antitrypsin deficiency, a condition known to have a less favorable surgical outcome. Finally, one patient was excluded due to a previous upper transverse laryngectomy, although CT and perfusion scanning patterns were compatible with surgery.

CONCLUSIONS

In our opinion, density mask helical CT yields more accurate and clearer images than perfusion scanning, and allows the patients candidate for surgery to undergo a single examination to evaluate the extent and distribution of emphysema and to detect other possible pathological conditions. Though ours was a small series, the results suggest that perfusion scanning be integrated with density mask helical CT, the latter a very important technique for surgical planning.

Secondary pulmonary hypertension does not adversely affect outcome after single lung transplantation

OBJECTIVE

Primary and secondary pulmonary hypertension have been associated with poor outcomes after single lung transplantation. Some groups advocate double lung transplantation and the routine use of cardiopulmonary bypass during transplantation in this population. However, the optimal procedure for these patients remains controversial. The goal of our study was to determine the safety of single lung transplantation without cardiopulmonary bypass in patients with secondary pulmonary hypertension.

METHODS

We retrospectively reviewed 76 consecutive patients with pulmonary parenchymal disease who underwent single lung transplantation from 1992 to 1998. Recipients were stratified according to preoperative mean pulmonary artery pressure. Secondary pulmonary hypertension was defined as parenchymal lung disease with a preoperative mean pulmonary artery pressure of 30 mm Hg or more. Patients with primary pulmonary hypertension or Eisenmenger's syndrome were excluded from analysis.

RESULTS

Eighteen of 76 patients had secondary pulmonary hypertension. No patient with secondary pulmonary hypertension required cardiopulmonary bypass, whereas 1 patient without pulmonary hypertension required bypass. After the operation, no significant differences were seen in lung injury as measured by chest radiograph score and PaO(2)/FIO(2) ratio, the requirement for inhaled nitric oxide, the length of mechanical ventilation, the intensive care unit or hospital length of stay, and 30-day survival. There were no differences in the forced expiratory volume in 1 second or 6-minute walk at 1 year, or the incidence of rejection, infection, or bronchiolitis obliterans syndrome greater than grade 2. Survival at 1, 2, and 4 years after transplantation was 86%, 79%, and 65%, respectively, in the low pulmonary artery pressure group and 81%, 81%, and 61%, respectively, in the group with secondary pulmonary hypertension (P >.2).

CONCLUSION

We found that patients with pulmonary parenchymal disease and concomitant secondary pulmonary hypertension had successful outcomes as measured by early and late allograft function and appear to have acceptable long-term survival after single lung transplantation. Our results do not support the routine use of cardiopulmonary bypass or double lung transplantation for patients with this disorder.

Severe pulmonary hypertension in histiocytosis X

Diminished exercise capacity in advanced pulmonary histiocytosis X does not appear to be related to ventilatory limitation but may be related to pulmonary vascular dysfunction. Pulmonary hemodynamics and respiratory function were studied in 21 consecutive patients with advanced pulmonary histiocytosis X, and compared with parameters of patients with other severe chronic lung diseases (29 patients with chronic obstructive pulmonary disease and 14 patients with idiopathic pulmonary fibrosis). All patients with pulmonary histiocytosis X displayed severe pulmonary hypertension: mean pulmonary arterial pressure, 59 +/- 4 mm Hg; cardiac index, 2.6 +/- 0.8 L/min/m(2); and total vascular pulmonary resistance, 25 +/- 3 IU/m(2) (p < 0.05, as compared with patients with other chronic lung diseases). Pa(O(2)) was similar in the three groups, whereas FEV(1) was lower in patients with other chronic lung diseases (p < 0.05). In contrast to other chronic lung diseases, the degree of pulmonary hypertension was not related to variables of pulmonary function in pulmonary histiocytosis X. Histopathology was available for 12 patients with pulmonary histiocytosis X and revealed proliferative vasculopathy involving muscular arteries and veins, with prominent venular involvement. Two consecutive lung samples (taken before and after the occurrence of pulmonary hypertension) were available for six patients with pulmonary histiocytosis X, and showed that pulmonary vasculopathy worsened, whereas parenchymal and bronchiolar lesions remained relatively unchanged. These results indicate that pulmonary hypertension in pulmonary histiocytosis X might be related to an intrinsic pulmonary vascular disease, in which the pulmonary circulation is involved independent of small airway and lung parenchyma injury.

Evidence-based preoperative evaluation of candidates for thoracotomy

All patients considered for thoracotomy should have preoperative spirometry. Patients meeting the criteria outlined below should also have quantitative radionuclide perfusion scanning. Patients felt to be at high risk on the basis of predicted postoperative FEV1 should be considered for exercise assessment. If exercise assessment is performed, an MVO2 of < 10-15 mL/kg/min or a predicted postoperative MVO2 < 10 mL/kg/min identifies a patient at very high risk for complications and mortality. Limited available data support the use of preoperative risk indices to identify patients at high risk (See Table 4). Lung volume reduction surgery may provide new approaches in selected patients with significant obstructive lung disease and concomitant lung cancer.

Neural drive to the diaphragm after lung volume reduction surgery

STUDY OBJECTIVES

The aim of this study was to investigate prospectively the changes in neural drive to the diaphragm in the first year after lung volume reduction surgery (LVRS) in patients with COPD.

PATIENTS AND METHODS

In 14 patients with severe emphysema (mean +/- SD; age, 53.7 +/- 8.3 years; FEV(1), 0.64 +/- 0. 18 L; residual volume [RV], 5.33 +/- 1.25 L; PaO(2), 62.3 +/- 9.0 mm Hg; PaCO(2), 39.0 +/- 6.0 mm Hg), we assessed lung function, arterial blood gases, maximal exercise capacity (Wmax), and oxygen uptake (f1.gif" BORDER="0">O(2)max); intrinsic positive end-expiratory pressure (PEEPi); diaphragmatic strength (transdiaphragmatic pressure, Pdisniff) and endurance capacity (tlim); central diaphragmatic drive assessed by root mean square analysis of the esophageal electromyogram (rmsdia); and isotime dyspnea during loaded breathing tests (BS).

RESULTS

Despite a significant increase (expressed as a percentage of baseline) in FEV(1) (40.6%) and a decrease in RV (30.0%) and PEEPi (75.7%) 1 month after LVRS, the improvements in Wmax (31.2%) and f1.gif" BORDER="0">O(2)max (13.7%); Pdisniff (25.4%) and tlim (64.9%); rmsdia (34.6%); and BS (21.7%) did not reach statistical significance (p < 0.05) until 6 months after LVRS. Arterial blood gases did not change significantly. Significant correlations were found between decrease in rmsdia and changes in PEEPi (r = 0.69), Wmax (r = -0.56), Pdisniff (r = -0.65), tlim (r = -0.59), and BS (r = 0.71) 6 months after LVRS.

CONCLUSIONS

Our results show that LVRS is able to increase the efficacy of the respiratory pump and by this way reduce ventilatory drive and respiratory effort sensation.

[Pediatric day surgery of the respiratory tract--indications and prioritization]

Ear, Nose and Throat (ENT) procedures are the most common types of surgery in children and include adenoidectomy, tonsillectomy, myringotomy, ventilation tube insertion or combinations of these. In order to study disease profile and routines for referral and treatment in outpatient otolaryngologic surgery, data were collected from 178 children operated consecutively during a six-week period in 1998. Median time from referral to surgery was less than four months. The majority of children operated for recurrent acute otitis media, tonsillitis or upper respiratory infections had suffered from the disease for 12 months or less. Obstructive symptoms were registered in 18% of these children. Most patients were referred to the hospital by specialists in otolaryngology or paediatric medicine. Surgery was more common in male than female-children, and median age at the time of surgery was 4.2 years. There was an equal distribution of middle ear and pharyngeal surgery.

Age-related changes in the epiglottis causing failure of nasal continuous positive airway pressure therapy

At 65 years of age, a former coal miner, now 72-years-old, developed a progressive loss of concentration with daytime sleepiness and sleep disturbances. Work-up in pneumological and medical sleep centres resulted in diagnosis of chronic obstructive pulmonary disease (COPD), borderline obstructive sleep apnoea syndrome and, later, upper airway resistance syndrome. In addition, there was evidence of reduced efficiency of sleep. Neither the initial administration of theophylline nor the later use at night of hyperbaric respiration led to improvement in the patient's symptoms. Instead, the patient developed loud snoring, as well as the inability to sleep while in a lying position. At age 71 years, otorhinolaryngological examination resulted in findings of age-related changes in the epiglottis, that completely blocked the hypopharynx upon inspiration. Polysomnography, which was possible only in a half-seated position, revealed reduction in deep sleep, with a maximum oxygen saturation of 77 per cent at an apnoea-hypopnoea index (AHI) of 4.8. Partial resection of the epiglottis with laser surgery resulted in complete improvement of diurnal drowsiness and reduced stamina. Sleeping in a supine position again became possible. Polysomnography revealed normalization of sleep architecture, but unchanged, low efficiency of sleep. This case underscores the importance of an interdisciplinary approach to the treatment of sleep-related breathing disorders.

Symptom experiences of lung transplant recipients: comparisons across gender, pretransplantation diagnosis, and type of transplantation

PURPOSES

To investigate symptom experiences of patients who have single and bilateral-sequential lung transplantation and to determine whether differences exist according to gender, pretransplantation diagnosis, and type of transplantation procedure.

DESIGN AND METHODS

In the context of a descriptive, comparative survey design, surviving recipients of single and bilateral-sequential lung transplants (n = 56) were mailed a symptom frequency and distress questionnaire. The response rate was 85.7% (n = 48). The average time since the recipients' lung transplantations was 1.5 +/- 0.7 years.

RESULTS

Recipients of lung transplants reported that several symptoms (eg, muscle weakness, shortness of breath with activity, and changed appearance) were both frequently occurring and quite distressing. Other symptoms were identified as being distressing, but not frequently occurring, or vice versa. Significant (P <.05) differences were found for symptom experiences among pretransplant diagnostic groups and between genders and types of transplant procedures.

CONCLUSIONS

These findings elucidate the symptom experiences of recipients of lung transplants and suggest that subgroup differences exist. The data provide a basis for strengthening patient and family education and for developing symptom management strategies. Further investigation of the symptom experiences of the recipients of lung transplants is needed, especially in relation to subgroups.

Dobutamine stress echocardiography for the preoperative evaluation of patients undergoing lung volume reduction surgery

BACKGROUND

Lung volume reduction surgery has been proposed as a bridge to lung transplantation and as definitive therapy for advanced chronic obstructive lung disease. However, patient selection criteria and optimal preoperative assessment have not been clearly defined.

OBJECTIVE

We investigated the feasibility, safety, and value of dobutamine stress echocardiography as a predictor of major early cardiac events in patients who underwent lung volume reduction surgery.

METHODS

The study population consisted of 46 patients (21 men and 25 women, mean age 59 +/- 9 years) who underwent dobutamine stress echocardiography (maximum dose 40 microg. kg(-1). min(-1) plus atropine if needed) 180 days or less before lung volume reduction surgery. Adverse cardiac events were prospectively defined and tabulated during hospitalization after the operation and at subsequent outpatient visits.

RESULTS

Dobutamine stress echocardiography was interpretable in 45 of 46 (98%) patients. There were no adverse events during testing. The studies revealed normal left ventricular systolic function at rest in all patients and normal right ventricular function in all patients but one. Thirteen patients had right ventricular enlargement. Estimated right ventricular systolic pressure was mildly elevated (>40 mm Hg) in 5 patients. Four patients (9%) had stress tests positive for ischemia. There were no perioperative deaths. Follow-up was available for 44 of 45 patients at a duration of 20.0 +/- 7.0 months. Two major adverse cardiac events occurred in the same patient in whom the results of dobutamine stress echocardiography were positive for ischemia (positive predictive value 25%, 95% confidence interval 0% to 83%; negative predictive value 100%, 95% confidence interval 90 to 100%).

CONCLUSION

Despite end-stage chronic obstructive lung disease and poor ultrasound windows, dobutamine stress echocardiography is feasible and safe in patients undergoing evaluation for lung volume reduction surgery. It yields important information on right and left ventricular function and has an excellent negative predictive value for early and late adverse cardiac events.

Lung volume reduction surgery (LVRS) for chronic obstructive pulmonary disease (COPD) with underlying severe emphysema

BACKGROUND

Lung volume reduction surgery (LVRS) has recently re-emerged as a surgical option for the treatment of end stage chronic obstructive pulmonary disease (COPD) due to underlying severe emphysema. Advocates of LVRS claim that it represents a significant breakthrough in the management of this challenging group of patients while sceptics point to uncertainty about the effectiveness of the operation.

METHODS

A systematic review was conducted of the evidence on the effects of LVRS in patients with end stage COPD secondary to severe emphysema.

RESULTS

The most rigorous evidence on the effectiveness of LVRS came from case series. Seventy five potentially relevant studies were identified and 19 individual series met the methodological criteria for inclusion. The pattern of results was consistent across individual studies despite a significant degree of clinical heterogeneity. Significant short term benefits occurred across a range of outcomes which appeared to continue into the longer term. Physiological improvements were matched by functional and subjective improvements. Early mortality rates were low and late mortality rates compared favourably with those of the general COPD population. However, the entire research base for the intervention is subject to the limitations of study designs without parallel control groups.

CONCLUSIONS

LVRS appears to represent a promising option in the management of patients with severe end stage emphysema. However, until the results of ongoing clinical trials are available, the considerable uncertainty that exists around the effectiveness and cost effectiveness of the procedure will remain.

Hyperacute rejection of a pulmonary allograft. Immediate clinical and pathologic findings

The clinical and pathologic findings seen in hyperacute rejection are well documented in renal and cardiac allografts. We describe the second case of hyperacute rejection in a pulmonary allograft and detail the immediate clinicopathologic findings. The patient underwent a single lung transplant for severe COPD with postoperative course complicated by acute rejection and graft failure. Eleven days later, the patient underwent a second transplant with intra-operative course complicated by rapid pulmonary edema and copious production of frothy, pink fluid from the bronchial orifice of the allograft followed by death within four hours of anastomoses. Intraoperative biopsy and autopsy demonstrated platelet/fibrin thrombi, marked interstitial neutrophilia, alveolar edema, and antibody deposition on the endothelial surface and vasculature walls. Prior to the first transplant, the patient's serum had 0% panel reactive antibody and was crossmatch compatible with the first allograft. The patient's serum prior to the second transplant contained cross-reacting antibodies to the donor's B and T lymphocytes. The immediate clinical findings in this case are similar to the findings in a previously reported case. This report is the first documentation of the immediate pathologic features of hyperacute rejection in a lung allograft which are similar to those seen with other organ allografts.

The effects of adenoid hypertrophy and subsequent adenoidectomy on pediatric nasal airway resistance

To investigate how adenoid hypertrophy and subsequent adenoidectomy affect pediatric airway resistance, we developed a prospective controlled study. Fifty children, aged 3 to 12 years, diagnosed with adenoid hypertrophy and selected for adenoidectomy, preoperatively had their nasal airway resistance assessed by active anterior rhinomanometry. Twenty-five of these children were subsequently followed up postoperatively, undergoing nasal resistance evaluations at 1 month, 3 months, 6 months, and 12 months. Another 25 children, without chronic upper airway obstruction symptoms, were enrolled as a control group, and their airway resistance was assessed in the same fashion. We concluded that the children selected for adenoidectomy, compared to the control group and before surgery, had mean resistance values up to two- to threefold higher, in both untreated and decongested nose states. Surgery was found to dramatically reduce airway resistance, but only in children under the age of seven. However, the postoperative values still tended to remain higher than the control subjects results. If in a significant number of children the operation failed in completely resolving their complaints, no pre-operative rhinomanometric pattern could be found to specifically relate to a complete surgical success.

Intralobar lung sequestration with systemic coronary arterial supply

Pulmonary sequestration is a rare anomaly. An accurate pre-operative evaluation of its vascular supply is essential for the surgeon's operative approach. We describe here an intrapulmonary sequestration with vascular arterial supply via the left circumflex and the right coronary artery. This case demonstrates that if aortography is unrevealing, then a coronary source should be considered in the preoperative search for the arterial supply to a pulmonary sequestration. Moreover, pulmonary sequestration should be listed in the differential diagnosis of aberrant coronary arteries.

Surgical treatment of chronic obstructive pulmonary disease

Over the past several decades, a number of surgical techniques have been developed for the treatment of chronic obstructive pulmonary disease. Many of these procedures have been abandoned because of lack of efficacy and/or high morbidity and mortality. At the present time, lung transplantation, reduction pneumoplasty for giant bullous emphysema, and lung volume reduction surgery are being performed in a number of centers. Data concerning the effectiveness of these procedures is accumulating and will ultimately need careful analysis to determine long-term outcomes in this group of patients.

Recombinant human growth hormone for reconditioning of respiratory muscle after lung volume reduction surgery

OBJECTIVE

To investigate the effects of recombinant human growth hormone (rHGH) as a "rescue treatment" in an end-stage chronic obstructive pulmonary disease patient after prolonged weaning failure.

DESIGN

Descriptive case report.

SETTING

Fifteen-bed intensive care unit in a university hospital.

PATIENT

A 62-year-old man with end-stage chronic obstructive pulmonary disease and pulmonary emphysema after lung reduction surgery and prolonged weaning failure after long-term mechanical ventilation.

INTERVENTIONS

After 42 days of unsuccessful weaning from the respirator, rHGH (27 IU/day, 0.3 IU/kg body weight/day) was administered for 20 days through a subcutaneous injection in addition to standard intensive care.

MEASUREMENTS AND MAIN RESULTS

In addition to daily routine laboratory studies, the visceral proteins prealbumin, retinol-binding protein, and transferrin, and nitrogen balance were measured twice a week, as were the thyroid hormones triiodothyronine, thyroxine, and thyroid-stimulating hormone, plasma insulin levels, and the insulin-like growth factor (IGF)-1 binding proteins IGF-BP1 and IGF-BP3. IGF-1 was measured from day 1 to day 4 of rHGH administration. Nutritional support was guided by indirect calorimetry. Additionally, weaning variables such as peak expiratory flow rate and expiratory tidal volume were measured noninvasively. T-piece weaning trials were carried out daily until respiratory muscle fatigue occurred. IGF-1 increased in response to rHGH stimulation, from 103 to 230 microg/mL, within 4 days. The carrier protein IGF-BP3 increased from 126 to 283 mg/L at the end of the study period, and the inhibiting IGF-BP1 decreased initially from 19 to 14 mg/L and then increased until the end of the study to 31 mg/L. Nitrogen balance increased initially from 4.6 to 13.6 g/24 hrs and thereafter decreased until the end of rHGH treatment to 8.3 g/24 hrs. Resting energy expenditure increased from 1800 to 2300 kcal/24 hrs. Peak expiratory flow rate increased from 0.69 to 0.88 L/sec. The expiratory tidal volume showed a slight increase during the study period during the daily decrease of pressure support on the ventilator setting. Respiratory muscular strength increased beginning 10 days after rHGH therapy was started. From this point, T-piece weaning trials could be prolonged almost daily. The patient was extubated successfully on postoperative day 75.

CONCLUSIONS

This case report shows that after a prolonged catabolic state and long-term mechanical ventilation, administration of rHGH not only enhances the response of protein metabolism but improves respiratory muscular strength. Therefore, it may reduce the duration of mechanical ventilation in selected patients.

[Chronic obstructive pulmonary disease and lung transplants: results in Spain]

OBJECTIVE

To determine the outcome of lung transplantation in patients with chronic obstructive pulmonary disease (COPD) in Spain.

METHODS

In all COPD patients transplanted at four Spanish hospitals over a period of seven years, we studied actuarial survival rates retrospectively using the Kaplan Meier test in relation to demographic characteristics, type of transplant, underlying disease, lung function evolution in terms of forced vital capacity (FVC), maximum expiratory flow in 1 second (FEV1) and gasometric evolution (PaO2 and PaCO2).

RESULTS

Seventy-four transplants were performed in COPD patients over a five-year period. Mean age was 47 +/- 7 years (26-61) and 77% of the patients were men. A diagnosis of emphysema was made in 58%, alpha-1 antitrypsin deficiency emphysema in 14% and chronic bronchitis in 28%. The likelihood of survival was 75% for the first year, 63% for two years and 41% for the third year. Lung function and blood gases improved significantly by the third month after transplantation: FVC was 1677 +/- 637 ml before transplantation and 2631 +/- 670 ml afterwards; FEV1 was 585 +/- 189 ml before transplantation and 2118 +/- 673 ml afterwards (p < 0.001). Double lung transplants achieved significantly greater improvement in function variables than did single-lung transplants (FVC 2843 +/- 681 ml and FEV1 2543 +/- 620 ml by the third month in DLT patients versus FVC 2402 +/- 587 ml and FEV1 1659 +/- 350 ml for SLT), with no significant differences in blood gases after the two types of transplant. Half the sing-lung transplant patients developed hyperinflation of the native lung and reached maximum lung function values, which tended to be lower than those for patients who did not experience this complication (FEV1 1638 +/- 349 ml versus 1930 +/- 307 ml, p = 0.051).

CONCLUSIONS

First-year mortality in patients with COPD undergoing lung transplantation in Spain is similar to that described in the International Transplant Registry. We found no differences between double- and single-lung transplant patients. Functional change is good for both types of transplantation, although this aspect of outcome is significantly better when two lungs are transplanted.

Initial experience with two sequential anterolateral thoracotomies for bilateral lung transplantation

BACKGROUND

Bilateral transsternal thoracotomy (clamshell incision) is the standard approach used for bilateral sequential lung transplantation (BLTX). The morbidity of this large incision can be considerable. Two separate sequential anterolateral thoracotomies represent a less invasive approach.

METHODS

The value of this approach was investigated in a prospective series of 13 consecutive patients with the underlying diagnosis of COPD or cystic fibrosis (group A). Results were compared to 8 consecutive patients with similar indications who had undergone BLTX via clamshell incision during the last year prior to this new technique (group B).

RESULTS

No intraoperative complications occurred in either group. The difference between the cold ischemic time of the 1st and 2nd transplanted lung was comparable between the 2 groups (81 min+/-17 min in group A vs 79 min+/-14 min in group B, p = 0.783). Postoperative restriction was significantly less in the group operated through 2 separate thoracotomies, as proven by the vital capacity in the first spirometry performed during the 3rd postoperative week (VC group A 55%+/-16% predicted vs 41%+/-11% predicted in group B; p = 0.043).

CONCLUSION

The bilateral sequential anterolateral thoracotomy represents a safe and less invasive approach for BLTX in patients with large chest volumes. It minimizes the operative trauma, improves postoperative functional recovery and prevents the potential spread of unilateral complications to the other pleural cavity.

Lung volume reduction surgery combined with cardiac interventions

OBJECTIVE

Postoperative course and functional outcome were evaluated in patients who underwent lung volume reduction surgery (LVRS) or in combination with valve replacement (VR), percutaneous transluminal coronary angioplasty (PTCA), placement of a stent, or coronary artery bypass grafting (CABG).

METHODS

Patients with severe bronchial obstruction and hyperinflation due to pulmonary emphysema were evaluated for lung volume reduction surgery. Cardiac disorders were screened by history and physical examination and assessed by coronary angiography. Nine patients were accepted for LVRS in combination with an intervention for coronary artery disease (CAD). In addition, three patients with valve disease and severe emphysema were accepted for valve replacement (two aortic-, one mitral valve) only in combination with LVRS. Functional results over the first 6 months were analysed.

RESULTS

Pulmonary function testing demonstrates a significant improvement in postoperative FEV1 in patients who underwent LVRS combined with an intervention for CAD. This was reflected in reduction of overinflation (residual volume/total lung capacity (RV/TLC)), and improvement in the 12-min walking distance and dyspnea. Median hospital stay was 15 days (10-33). One patient in the CAD group died due to pulmonary edema on day 2 postoperatively. One of the three patients who underwent valve replacement and LVRS died on day 14 postoperatively following intestinal infarction. Both survivors improved in pulmonary function, dyspnea score and exercise capacity. Complications in all 12 patients included pneumothorax (n = 2), hematothorax (n = 1) and urosepsis (n = 1).

CONCLUSION

Functional improvement after LVRS in patients with CAD is equal to patients without CAD. Mortality in patients who underwent LVRS after PTCA or CABG was comparable to patients without CAD. LVRS enables valve replacement in selected patients with severe emphysema otherwise inoperable.

Relationship between resting hypercapnia and physiologic parameters before and after lung volume reduction surgery in severe chronic obstructive pulmonary disease

Patients with severe chronic obstructive pulmonary disease (COPD) have varying degrees of hypercapnia. Recent studies have demonstrated inconsistent effects of lung volume reduction surgery (LVRS) on PaCO2; however, most series have excluded patients with moderate to severe hypercapnia. In addition, no study has examined the mechanisms responsible for the reduction in PaCO2 post-LVRS. We obtained spirometry, body plethysmography, diffusion capacity, respiratory muscle strength, 6-min walk test, and incremental symptom-limited maximal exercise data in 33 consecutive patients pre- and 3 to 6 mo post-LVRS, and explored the relationship between changes in PaCO2 and changes in the measured physiologic variables. All patients underwent bilateral LVRS via median sternotomy and stapling resection by the same cardiothoracic surgeon. Patients were 57 +/- 8 yr of age with severe COPD, hyperinflation, and air trapping (FEV1, 0.73 +/- 0.2 L; TLC, 7.3 +/- 1.6 L; residual volume [RV], 4.8 +/- 1.4 L), and moderate resting hypercapnia (PaCO2, 44 +/- 7 mm Hg; range, 32 to 56 mm Hg). Post-LVRS, PaCO2 decreased by 4% (PaCO2 pre 44 +/- 7 mm Hg, PaCO2 post 42 +/- 5 mm Hg; p = 0.003). Patients with higher baseline values of PaCO2 had the greatest reduction in PaCO2 post-LVRS (r = -0.61, p < 0.001). Significant correlations existed between reduction in PaCO2 and changes in FEV1 (r = -0.56; p = 0.0007), maximal inspiratory pressure (PImax) (r = -0.46; p = 0.009), diffusing capacity of the lungs for carbon monoxide (DLCO) (r = -0.47; p = 0.008), and RV/TLC (r = 0.41; p = 0. 02). Correlation existed also between reduction in PaCO2 and breathing pattern at maximal exercise: maximal minute ventilation (V Emax) (r = -0.47; p = 0.009), and tidal volume (VT) (r = -0.40; p = 0.02). The changes in PaCO2 post-LVRS showed marked intersubject variability. We conclude that LVRS, by reducing hyperinflation, air trapping, and improving respiratory muscle function, enables the lung and chest wall to act more effectively as a pump, thereby increasing alveolar ventilation and reducing baseline resting PaCO2. In addition, patients with higher baseline levels of PaCO2 demonstrate the greatest reduction in PaCO2 post-LVRS, and should not be excluded from receiving LVRS.

[Evaluation of surgical risk in patients with COPD]

In this overview general risk factors for postoperative complications are discussed with special reference to pulmonary complications, which frequently occur in patients with chronic obstructive pulmonary disease (COPD). In a second part the functional evaluation of lung resection candidates is presented. Pulmonary complications are the most frequent cause of postoperative morbidity and mortality. Risk factors include: underlying respiratory disease, especially COPD, current smoking, duration of anaesthesia, type of surgical procedure (upper abdominal or thoracic surgery), age and obesity. The preoperative evaluation of patients at risk is discussed. For non-thoracic surgery preoperative pulmonary function testing and a preoperative chest radiograph are indicated for high-risk patients only, whereas they are mandatory for all lung resection candidates. There are no cut-off values in pulmonary function testing which would preclude non-thoracic surgical procedures. In patients with COPD, laparascopic procedures are recommended; and regional or epidural anaesthesia have less adverse effects on pulmonary function than general anaesthesia. Prevention of postoperative pulmonary complications includes smoking cessation at least eight weeks before surgery, and, if indicated preoperative treatment with antibiotics, beta2-agonists, steroids (steroid-trial) and intensive perioperative chest physiotherapy (incentive spirometry). The functional reserves of lung resection candidates is assessed with an algorithm based on the forced expiratory volume in one second (FEV1), the transfer factor of the lung for carbon monoxide (DLCO), and the maximal oxygen uptake on exercise (VO2max). In critical patients additional split function studies are necessary to estimate the remaining pulmonary function depending on the extent of resection.

Effect of lung volume reduction surgery on diaphragm length in severe chronic obstructive pulmonary disease

Lung volume reduction surgery (LVRS) has been suggested as improving respiratory mechanics in patients with severe chronic obstructive pulmonary disease (COPD). We hypothesized that LVRS might lengthen the diaphragm, increase its area of apposition with the chest wall, and thereby improve its mechanical function. To determine the effect of bilateral LVRS on diaphragm length, we measured diaphragm length at TLC, using plain chest roentgenograms (CXRs), in 25 patients (11 males and 14 females) before LVRS and 3 to 6 mo after LVRS. A subgroup of seven patients (reference data) also had diaphragm length measurements made with CXRs, using films made within a year before their presurgical evaluation. Right hemidiaphragm silhouette length (PADL) and the length of the most vertically oriented portion of the right hemidiaphragm muscle (VDML) were measured. Diaphragm dome height was determined from the: (1) distance between the dome and transverse diameter at the manubrium; and (2) highest point of the dome referenced horizontally to the vertebral column. Patients also underwent spirometry, measurements of lung volumes and diffusion capacity, an incremental symptom-limited maximum exercise test, and measurements of 6 min walk distance (6MWD) and transdiaphragmatic pressures during maximum static inspiratory efforts (Pdimax sniff) and bilateral supramaximal electrophrenic twitch stimulation (Pditwitch) both before and 3 mo after LVRS. Patients were 58 +/- 8 yr of age, with severe COPD and hyperinflation (FEV1 = 0.68 +/- 0.23 L, FVC = 2.56 +/- 7.3 L, and TLC = 143 +/- 22% predicted). Following LVRS, PADL increased by 4% (from 13.9 +/- 1.9 cm to 14.5 +/- 1.7 cm; p = 0.02), VDML increased by 44% (from 2.08 +/- 1.5 cm to 3.00 +/- 1.6 cm, p = 0.01), and diaphragm dome height increased by more than 10%. In contrast, diaphragm lengths were similar in subjects with CXRs made before LVRS and within 1 yr before evaluation. The increase in diaphragm length correlated directly with postoperative reductions in TLC and RV, and also with increases in transdiaphragmatic pressure with maximal sniff (Pdimax sniff), maximal oxygen consumption (V O2max), maximal minute ventilation (V Emax), and maximum voluntary ventilation following LVRS. We conclude that LVRS leads to a significant increase in diaphragm length, especially in the area of apposition of the diaphragm with the rib cage. Diaphragm lengthening after LVRS is most likely the result of a reduction in lung volume. Increases in diaphragm length after LVRS correlate with postoperative improvements in diaphragm strength, exercise capacity, and maximum voluntary ventilation.

Persistent increases of BAL neutrophils as a predictor of mortality following lung transplant

STUDY OBJECTIVES

To evaluate whether findings from surveillance bronchoscopy predict survival following lung transplantation.

DESIGN

Retrospective review and analysis of 498 bronchoscopies with transbronchial biopsy (TBB) and BAL performed in 34 patients after lung transplantation.

SETTING

University-based, tertiary referral medical center.

PATIENTS

Thirty-four patients after lung transplantation. The mean age at transplantation was 49+/-9 years; 20 (59%) were female. Twenty-four (71%) underwent single and 10 (29%) underwent bilateral lung transplantation. The most common pretransplantation diagnostic groups were emphysema/COPD without concomitant alpha1-antiprotease deficiency (n = 13) and other obstructive disease processes (n = 10).

INTERVENTIONS

Over follow-up, subjects underwent multiple bronchoscopies with TBB and BAL. The median number per subject was 15 (25 to 75% range 13 to 17).

MEASUREMENTS AND RESULTS

We calculated the overall median BAL WBCs and median percent neutrophils (polymorphonuclear leukocytes [PMNs]) among all of the BALs performed for each subject. We then calculated the mean +/- SD of those median values. We used Cox proportionate hazards to assess mortality risk. The median overall follow-up observation period for the cohort was 560 days. There were 11 deaths during this period. Twenty-four subjects (71%) had acute rejection (AR) grades 2 to 4 (mild to severe), and nine (27%) had obliterative bronchiolitis (OB) diagnosed by TBB at any point. The mean value for BAL WBCs was 366+/-145 x 10(3) per milliliter; for percentage PMNs, the mean was 7+/-10%. Adjusting for age, gender, single vs bilateral lung transplantation, pretransplantation diagnostic group, presence of AR, presence of OB, BAL WBC concentration, and lymphocyte CD4/CD8 ratio, PMN percent was a significant predictor of mortality (p = 0.02).

CONCLUSIONS

Ongoing inflammation manifested by an increased percentage PMNs over repeated bronchoscopies predicts mortality following lung transplantation. Biopsy data alone may be insufficient to identify posttransplantation patients at risk of poor outcome.

Airway obstruction and perioperative complications in smokers undergoing abdominal surgery

BACKGROUND

The goal of this study was to determine whether airway obstruction determined by preoperative spirometry predicts perioperative complications in smokers undergoing abdominal surgery whose treatment is managed according to current clinical practice.

METHODS

A pulmonary function database identified patients undergoing abdominal surgery who met the following criteria for airway obstruction (n = 135): a forced expiratory volume less than 40% of predicted normal value, a forced expiratory volume:forced vital capacity ratio less than the lower limit of predicted normal, a smoking history of more than 20 pack-years, and an age older than 35 yr. A group of patients without airway obstruction (n = 135) was matched for gender, surgical site (upper vs. lower abdominal), smoking history, and age. Medical records were reviewed by an abstractor to identify perioperative complications that occurred within 30 days after surgery.

RESULTS

The forced expiratory volume values were 0.9+/-0.21 (mean +/- SD) and 2.9+/-0.61 in patients with and without airway obstruction, respectively. When analyzed by conditional logistic regression using the 1:1 matched-pairs feature, including age, pack-year smoking history, site of incision, and current smoking status as covariates, in patients with airway obstruction bronchospasm was more likely to develop (odds ratio, 6.9 [95% confidence interval, 1.2 to 38.4]) but the patients were not more likely to need prolonged endotracheal intubation (odds ratio, 1.1 [95% confidence interval, 0.4 to 3.2]). They were also no more likely to need prolonged intensive care admission or readmission. The frequency of other complications was less than 5%.

CONCLUSION

When other factors were considered, preoperative airway obstruction predicted the occurrence of bronchospasm, but not prolonged endotracheal intubation, in smokers undergoing abdominal surgery who are treated according to current clinical practices.

[Chronic heart or lung disease and psychosocial stress]

Ten boys and 15 girls below the age of 16, were referred to the National Hospital in Norway for evaluation for heart or lung transplantation 1990-97. 24 of the children and their families went through a thorough psychosocial assessment in order to assess the supportive measures the children and their families might need for coping with stress during the evaluation and the follow-up period. The patients were divided into three diagnostic groups: Two had cystic fibrosis and one an obstructive lung disease, heart-lung group, eight had congenital heart disease and 13 cardiomyopathy. 15 children were accepted for transplantation and placed on the waiting list. The others were rejected for medical reasons. Seven children (29%) filled the criteria for a psychiatric diagnosis (six anxiety disorders and one depression). Five others had considerable anxiety symptoms. The cardiomyopathy group had fewer problems than the heart-lung and congenital heart disease groups. The study shows that families with children suffering from life-threatening disease live with a great deal of stress and are in need of help and support. Many families are either not aware of their rights or too exhausted to seek help.

Improvements in lung function, exercise, and quality of life in hypercapnic COPD patients after lung volume reduction surgery

STUDY OBJECTIVE

To determine the impact of preoperative resting hypercapnia on patient outcome after bilateral lung volume reduction surgery (LVRS).

METHODS

We prospectively examined morbidity, mortality, quality of life (QOL), and physiologic outcome, including spirometry, gas exchange, and exercise performance in 15 patients with severe emphysema and a resting PaCO2 of > 45 mm Hg (group 1), and compared the results with those from 31 patients with a PaCO2 of < 45 mm Hg (group 2).

RESULTS

All preoperative physiologic and QOL indices were more impaired in the hypercapnic patients than in the eucapnic patients. The hypercapnic patients exhibited a lower preoperative FEV1, a lower diffusing capacity of the lung for carbon monoxide, a lower ratio of PaO2 to the fraction of inspired oxygen, a lower 6-min walk distance, and higher oxygen requirements. However, after surgery both groups exhibited improvements in FVC (group 1, p < 0.01; group 2, p < 0.001), FEV1 (group 1, p=0.04; group 2, p < 0.001), total lung capacity (TLC; group 1, p=0.02; group 2, p < 0.001), residual volume (RV; group 1, p=0.002; group 2, p < 0.001), RV/TLC ratio (group 1, p=0.03; group 2, p < 0.001), PaCO2 (group 1, p=0.002; group 2, p=0.02), 6-min walk distance (group 1, p=0.005; group 2, p < 0.001), oxygen consumption at peak exercise (group 1, p=0.02; group 2, p=0.02), total exercise time (group 1, p=0.02; group 2, p=0.02), and the perceived overall QOL scores (group 1, p=0.001; group 2, p < 0.001). However, because the magnitude of improvement was similar in both groups, and the hypercapnic group was more impaired, the spirometry, lung volumes, and 6-min walk distance remained significantly lower post-LVRS in the hypercapnic patients. There was no difference in mortality between the groups (p=0.9).

CONCLUSIONS

Patients with moderate to severe resting hypercapnia exhibit significant improvements in spirometry, gas exchange, perceived QOL, and exercise performance after bilateral LVRS. The maximal achievable improvements in postoperative lung function are related to preoperative level of function; however, the magnitude of improvement can be expected to be similar to patients with lower resting PaCO2 levels. Patients should not be excluded from LVRS based solely on the presence of resting hypercapnia. The long-term benefit of LVRS in hypercapnic patient remains to be determined.

Pulmonary rehabilitation and self-care after ambulatory surgery

Over 30 million Americans are living with chronic lung disease in the United States. The long-term ongoing care required by these individuals is a major contributor to American health care costs. Clinicians caring for persons with chronic respiratory disease are faced with minimal time in which to prepare patients for adequate self-care abilities. Often times, the clinician may assume that all of the "bases have been covered." In reality, it is because this assumption is made that persons with chronic respiratory disease are often not receiving the full breadth of information that they need to increase their self-care abilities and optimize their quality of life. This article prepares the perianesthesia clinician to ensure that the important tenets of self-care information are addressed for the person with overt and/or underlying chronic respiratory disease.

Determinants of abnormal maximum oxygen uptake after lung transplantation for chronic obstructive pulmonary disease

BACKGROUND

Single lung transplantation for chronic obstructive pulmonary disease relieves a ventilatory limit to incremental exercise, but maximum oxygen uptake remains abnormal. The purpose of this study was to define the relative contributions of Fick principle variables to abnormal aerobic capacity after lung transplantation.

METHODS

Twelve paired incremental cardiopulmonary exercise test results obtained before and 3 to 6 months after single lung transplantation for chronic obstructive pulmonary disease were compared.

RESULTS

Maximum workload nearly doubled after operation (42.5+/-4.2 vs 25.5+/-4.7 watts, P < .05). Peak exercise minute ventilation increased (32.8+/-3.3 vs 21+/-2.4 L/min, n = 11, P < .05), but maximum oxygen uptake remained markedly abnormal after transplantation (46.6%+/-4.4% vs 32.1%+/-2.9% predicted, P < .05, n = 8). Peak exercise cardiac output was normal (11.0+/-1.4 L/min, 89% predicted), but arterial-mixed venous oxygen content difference at peak exercise was only half of normal (7.2+/-0.61 mL/dL), as a result in part of the failure of mixed venous oxygen saturation to fall normally (peak exercise SvO2 = 49.8%+/-2.8%).

CONCLUSIONS

Lung transplantation for chronic obstructive pulmonary disease relieves a ventilatory limit to exercise, but maximum aerobic capacity remains abnormal, in part because of abnormal systemic O2 extraction.

[Role of surgery in the treatment of obstructive respiratory insufficiency]

Within 15 years, the prognosis of chronic obstructive respiratory failure has been deeply modified by advances in surgical treatment. In case of emphysema, lung volume reduction permits an improvement in the functional status in a significant number of patients, at least for several years. Moreover, lung transplantation, mainly single lung transplantation, provide currently an actuarial survival rate of 50% at five years.

Limitations of radionuclide angiographic assessment of left ventricular systolic function before lung transplantation

To evaluate the influence of increased right ventricular afterload on radionuclide assessment of the left ventricular ejection fraction (LVEF), we compared the preoperative and postoperative value of isotopic LVEF in 11 patients who underwent lung transplantation and had a preoperative LVEF value below 55% (normal value: 68 +/- 8%). The underlying disease conditions were obstructive lung disease (n = 7) and pulmonary fibrosis (n = 4). The transplantation procedure was unilateral in 10 patients and bilateral in one. The mean value of isotopic LVEF prior to transplantation was 51 +/- 3% (range: 49% to 55%). At 42 +/- 13 mo postoperatively, isotopic LVEF increased significantly, to 65 +/- 10% (p = 0.001), suggesting that intrinsic left ventricular systolic function was in fact normal in these patients. We hypothesize that the low preoperative isotopic LEVF was not related to intrinsic dysfunction of the left ventricle, but rather to right ventricular pressure overload, leading to bulging of the interventricular septum into the left ventricle and to subsequent geometric distortion of the left ventricle. We conclude that isotopic LVEF may underestimate intrinsic left-ventricular systolic function in patients with severe chronic lung disease. Candidates for lung transplantation should not be rejected on the basis of a low isotopic LVEF, provided echocardiographic examination does show apparently normal left ventricular contraction.

Effects of isoflurane on oxygenation during one-lung ventilation in pulmonary emphysema patients

BACKGROUND

Hypoxic pulmonary vasoconstriction has an important role in human one-lung ventilation (OLV) in the lateral decubitus position under general anesthesia. During OLV, inhalational anesthesia may inhibit hypoxic pulmonary vasoconstriction and the decrease in arterial oxygenation. We studied the effect of isoflurane administration on arterial oxygen tension in chronic obstructive pulmonary disease patients.

METHODS

Ten patients who had thoracoscopic laser ablation of bullous emphysema were studied. Patients received 2% isoflurane in oxygen from induction until the first 20 min of OLV in the lateral decubitus position, then were switched to 1% isoflurane lasting 20 min and next were switched to 0.5% isoflurane lasting 20 min. After each 20-min inhalation, pulmonary and hemodynamic parameters were measured. The given concentrations for isoflurane were merely vapor meter concentrations.

RESULTS

PaO2/FIO2, Qs/Qt respiratory rate peak inspiratory pressure and PaCO2 showed no significant changes at each point of isoflurane. Expiratory tidal volume significantly decreased (P < 0.05) with 0.5% isoflurane compared to that with 2% isoflurane. Cardiac output, mean arterial pressure, mean pulmonary arterial pressure, systemic vascular resistance and pulmonary vascular resistance showed no significant changes at each point of isoflurane.

CONCLUSIONS

In patients with pulmonary emphysema, arterial oxygenation is not affected by low isoflurane concentration during OLV in the lateral decubitus position.

[Persistent pulmonary opacification as a sequela of portopulmonary shunt in portal vein thrombosis]

Portopulmonary venous anastomosis are a very rare complication of chronic liver diseases. We report on a patient with a cryptogenic liver cirrhosis and thrombosis of the portal vein who underwent antibiotic treatment because of recurrent pneumonias several times. Although treated successfully a pulmonal infiltrate persisted in further radiologic controls. By means of a velocity-encoded MRI a portopulmonary shunt of 30% of the cardiac output was assured. An operative correction with a distal splenorenal shunt was performed successfully. Former reports of portopulmonary anastomoses complicating chronic liver disease never were hemodynamically relevant. In the presented case, a portopulmonary anastomosis lead to recurrent pneumonias and a restrictive ventilatory disorder.

Lung transplantation

Although we have not yet obtained the survival results that have been observed in heart and renal transplantation, the survival rate in lung transplantation is improving. Because the lung is the only organ that is continuously exposed to the environment after transplantation, infection continues to be the major cause of early and late morbidity and mortality. Bronchiolitis obliterans, the second most common cause of late morbidity and mortality, is a progressive and currently untreatable condition resulting in lung dysfunction. The cause of this condition after transplantation is likely multifactorial and related to processes that result in allograft lung injury, such as rejection, bacterial infection, and cytomegalovirus infection. Future improvement in intermediate and long-term survival after lung transplantation will largely depend on prevention and long-term control of infection and subclinical rejection.

Lobectomy improves ventilatory function in selected patients with severe COPD

BACKGROUND

Patients often undergo limited resection instead of lobectomy for non-small cell lung cancer because of a low preoperative forced expiratory volume in 1 second (FEV1). Our goal is to define criteria that will preoperatively identify a group of patients who will not lose further function after lobectomy.

METHODS

Patients who underwent lobectomy with a preoperative FEV1 of less than 80% of predicted were retrospectively identified. Data collected included preoperative and postoperative pulmonary function tests, age, sex, the lobe resected, and preoperative ventilation-perfusion scan result.

RESULTS

Thirty-two patients were included in this study. The median preoperative FEV1 was 60% of predicted (1.65 L) and the mean change in FEV1 was a loss of 7.8% after lobectomy. The patients were divided into two groups. Group 1 (n = 13) had a preoperative FEV1 of less than or equal to 60% of predicted (median, 49%; 1.35 L) combined with an FEV1 to forced vital capacity ratio of less than or equal to 0.6. Group 2 (n = 19) includes all other patients (median preoperative FEV1, 69% of predicted; 1.87 L). The mean changes in FEV1 after lobectomy were +3.7% and -15.7% for groups 1 and 2, respectively (p < 0.005). A chronic obstructive pulmonary disease index was defined and then calculated for each patient. The relationship between this index and the change in FEV1 after lobectomy for all 32 patients appears linear (r = -0.43; p = 0.015).

CONCLUSIONS

Patients with a very low preoperative FEV1 and FEV1 to forced vital capacity ratio are less likely to lose ventilatory function after lobectomy and may actually improve it.

Primary graft failure following lung transplantation

STUDY OBJECTIVES

To determine the incidence of primary graft failure (PGF) following lung transplantation, assess possible risk factors, and characterize its effect on outcomes.

METHODS

Retrospective review of 100 consecutive patients undergoing lung transplantation at the University of Pennsylvania Medical Center. Fifteen patients meeting diagnostic criteria for PGF (PGF+ group) were compared with 85 patients without this complication (PGF- group).

RESULTS

The incidence of PGF was 15%. There was no significant difference in age, sex, underlying pulmonary disease, preoperative pulmonary artery systolic pressure, type of transplant, allograft ischemic times, use of cardiopulmonary bypass, or use of postoperative prostaglandin E1 infusion between the PGF+ and PGF- groups. Induction therapy with antilymphocyte globulin was used less frequently in the PGF+ group (p<0.005). Duration of mechanical ventilatory support was 36+/-43 days vs 4+/-6 days for the PGF+ and PGF- groups, respectively (p<0.0001). Hospital stay was significantly longer in the PGF+ group, averaging 75+/-105 days, compared with 27+/-38 days in the PGF group (p<0.005). One-year actuarial survival for the PGF+ group was only 40% compared with 69% for the PGF- group (p<0.005). Five of the six PGF+ survivors were ambulatory by 1 year; three were completely independent while two continued to require assistance with activities of daily living. Six-minute walk test distance among the ambulatory patients averaged 883+/-463 feet (range, 200 to 1,223 feet) compared with 1513+/-424 feet for the PGF- group (p<0.005). Among the subset of survivors who underwent single lung transplantation for COPD, the mean percent predicted FEV1 at 1 year was 43% for the PGF+ group and 55% for the PGF- groups, but this difference was not statistically significant.

CONCLUSIONS

PGF is a devastating postoperative complication, occurring in 15% of patients in the current series, and it is associated with a high mortality rate, lengthy hospitalization, and protracted and often compromised recovery among survivors.

Effect of lung volume reduction surgery in a rabbit model of bullous lung disease

Clinical use of staple lung volume reduction surgery (LVRS) has proliferated for treatment of emphysema despite limited data regarding efficacy or optimal techniques. Recent studies in animal models of obstructive lung disease describe the decrease in lung compliance and increase in airway support as mechanisms of an improvement in pulmonary functions analogous to human data. We describe contrasting results in an animal model of bullous lung disease with a mixed but predominantly restrictive pattern of lung disease. Mixed restrictive and bullous lung disease was induced in 17 New Zealand white rabbits with i.v. Sephadex beads and endotracheally instilled carrageenan. Unilateral stapled lung volume reduction surgery was performed at 5 weeks postinduction of emphysema on the right lower lobe by lateral thoracotomy using a pediatric stapler. Static trans-pleural pressures were measured at 60, 40, and 20 cm3 inflation at preinduction (baseline), pre- and postoperatively, and 1 week postoperatively in anesthetized animals. Lungs were then harvested en bloc and examined histopathologically. The effects of volume reduction surgery on static lung compliance, lung conductance, and forced expiratory flows (FEF) were assessed. Five weeks after induction of lung disease, the animals had no significant change in static compliance and forced expiratory volume in 0.5 s (FEV0.5) or lung conductance compared to baseline. Immediately following LVRS, the animals showed a significant decrease in static compliance, FEV0.5, and conductance. One week postoperatively, compliance increased to approximately baseline levels along with a slight increase in FEFs and conductance toward preoperative levels. Histology examination revealed restrictive and bullous lung disease. Thus, we have demonstrated the feasibility of using an animal model for evaluation of volume reduction therapy for restrictive-obstructive lung disease. Physiologically, this model showed decrease conductance and decreased forced expiratory flows following lung volume reduction despite increased recoil. This is in contrast to increased conductance and flows seen in humans with severe emphysema following surgery and suggests that current criteria excluding patients with a significant restrictive component to their lung disease from LVRS surgery may be justified.