Children at high altitude have less nocturnal periodic breathing than adults.

Although children commonly travel to high altitudes, their respiratory adaptation to hypoxia remains elusive. Therefore, in the present study respiratory inductive plethysmography, pulse oximetry (S(p,O(2))) and end-tidal CO(2) tension (P(ET,CO(2))) were recorded in 20 pre-pubertal children (aged 9-12 yrs) and their fathers during 1 night in Zurich (490 m) and 2 nights at the Swiss Jungfrau-Joch research station (3,450 m) following ascent by train within <3 h. In children, mean+/-sd nocturnal S(p,O(2)) fell from 98+/-1% at 490 m to 85+/-4 and 86+/-4% at 3,450 m (nights 1 and 2, respectively); P(ET,CO(2)) decreased significantly from 37+/-6 to 32+/-3 and 33+/-4 mmHg (3,450 versus 490 m). In adults, changes in nocturnal S(p,O(2)) and P(ET,CO(2)) at 3,450 m were similar to those in children. Children spent less time in periodic breathing at 3,450 m during night 1 and 2 (8+/-11 and 9+/-13%, respectively) than adults (34+/-24 and 22+/-17%, respectively), and their apnoea threshold for CO(2) was lower compared with adults (27+/-2 and 30+/-2 mmHg, respectively, both nights). S(p,O(2)), P(ET,CO(2)) and time in periodic breathing at altitude were not correlated between children and their fathers. In conclusion, children revealed a similarly reduced nocturnal O(2) saturation and associated hyperventilation at high altitude as adults but their breathing pattern was more stable, possibly related to a lower apnoea threshold for CO(2).

Isradipine improves endothelium-dependent vasodilation in normotensive coronary artery disease patients with hypercholesterolemia.

OBJECTIVE: The dihydropyridine calcium antagonist isradipine has anti-atherosclerotic effects in animals and improves endothelium-mediated nitric oxide (NO)-dependent vasodilation in vitro. As improved endothelial function may be beneficial we investigated its effects in patients with a high likelihood of endothelial dysfunction. DESIGN: Thirty patients (two female, age 55.4 +/- 10.5 years) with known coronary artery disease and elevated (> 6 mmol/l) total cholesterol (cholesterol: mean 6.7 +/- 0.78 mmol/l) or a cholesterol/high density lipoproteins (HDL) ratio of > 5 not on lipid lowering therapy, participated in the study. Endothelial vasodilator function was assessed before and after double-blind, randomized administration of isradipine 5 mg/day or placebo for 3 months. METHODS: Endothelial function was assessed as forearm blood flow (FBF, venous occlusion plethysmography) responses to graded brachial artery infusions of acetylcholine (Ach), to the NO-synthase blocker NG-monomethyl-L-arginine (L-NMMA) and to the endothelium-independent vasodilator sodium nitroprusside (SNP). Blood pressure was measured either directly from the brachial arterial or by sphygmomanometer during clinic visits. RESULTS: Blood pressure was unchanged in both groups after 3 months (isradipine: 88.8 versus 92.1 mmHg; placebo: 81.0 versus 82.5 mmHg; NS) but cholesterol levels decreased similarly in both groups (isradipine: 6.7 versus 6.1 mmol/l, NS; placebo: 6.6 versus 5.9 mmol/l, P< 0.05). The vasodilator response to SNP and the decrease in FBF in response to blockade of NO synthesis by L-NMMA were unchanged in both groups. However, isradipine, but not placebo, enhanced the NO-dependent vasodilator response to Ach (P < 0.05). CONCLUSION: Isradipine improves acetylcholine-mediated vasodilation in hypercholesterolemic patients independent of changes in lipids or blood pressure.

Mechanisms of carvedilol action in human congestive heart failure.

The precise mechanism by which beta-adrenoceptor blockers exert their beneficial actions in patients with heart failure remains unclear. Several possibilities have been proposed, including heart rate reduction, beta2-adrenoceptor-mediated modulation of catecholamine release, antagonism of the receptor-mediated toxic actions of norepinephrine on the myocardium, and favorable effects on myocardial energetics. In the present study we evaluated the effect of 3 months of carvedilol therapy on hemodynamics, total systemic and cardiac norepinephrine spillover (isotope dilution method), and myocardial metabolism (myocardial oxygen consumption and carbon dioxide release) in 10 patients with severe congestive heart failure. Although carvedilol treatment was associated with a significant improvement in left ventricular ejection fraction (17+/-1% to 28+/-3%; P<0.01) and left ventricular stroke work (87+/-13 to 119+/-21 g. m per beat; P<0.05), this effect was unrelated to changes in total systemic or cardiac norepinephrine spillover. The rise in left ventricular stroke work was accompanied by a modest rise in myocardial oxygen consumption per beat (0.33+/-0.04 to 0.42+/-0.04; P=0.05), although contractile efficiency was unchanged. The favorable effects of carvedilol on ventricular function in the failing heart are not explained by alterations in norepinephrine release or by changes in myocardial contractile efficiency.

Rationale and perspective of endothelin-1 antagonism in acute heart failure.

A role of the potent and long-acting vasoconstrictor peptide endothelin (ET)- I in the pathophysiology of chronic human heart failure has been postulated, based upon indirect evidence such as elevated plasma ET-1 levels and their relationship to the degree of haemodynamic impairment. Acute heart failure shares many features of chronic heart failure, albeit in an exaggerated fashion. As both the mixed ETA/ETB-receptor antagonist bosentan and the selective ETA receptor antagonist BQ 123 acutely improved the haemodynamics of chronic heart failure patients, there seems to be good reason to believe that ET-1 receptor antagonism may also be of benefit in the setting of acute heart failure. However, appropriate trials will have to be performed to document the clinical benefit of such an approach. Finally, the question remains open as to whether mixed ET-1 receptor antagonists like bosentan will prove better, worse or equal to antagonists that block the ETA, receptor only.

[Long-term results of the surgical treatment in acute aortic valve endocarditis]. / Langzeitresultate der chirurgischen Behandlung der akuten Aortenklappenendokarditis.

Late results after surgery for acute infectious aortic endocarditis using allografts are compared with those achieved with bioprostheses or mechanical heart valves. Cryopreserved allografts were used in 74 (22%) and prosthetic heart valve in 262 out of 336 (78%) patients presenting acute aortic endocarditis. Prosthetic (p = 0.001) and destructive endocarditis (p = 0.001) were more frequent in patients receiving allografts. Mean follow-up time was 6.6 +/- 4 years (range, 3 to 28 years). The 30-day-mortality was 19% for allograft patients and 6% for those receiving prosthetic heart valves (p = 0.002). Early reoperation, postoperative renal failure and sepsis did not differ between groups. After 20 years, actuarial survival was 60% for mechanical heart valves, 44% for bioprosthesis and 38% for allografts (p = 0.003), reoperation was unnecessary in 52% of mechanical heart valves and 10% of bioprostheses and allografts (p = 0.0007). Acute infection at the time of operation (p = 0.0001), redo surgery (p = 0.0006), staphylococci (p = 0.0003), older age (p = 0.004) and mitral valve involvement (p = 0.004) were risk factors for late death, irrespective of preoperative antibiotic treatment and type of prosthesis used. A longer bypass and aortic cross-clamp time predicted early (p = 0.0001) and late survival (p = 0.0001), independently. Destructive aortic endocarditis has a poor long-term outcome irrespective of the use of allografts. Acute infection at the time of surgery predicted early and late death; however, surgery is indicated prior to secondary involvement of the mitral valve. The duration of preoperative antibiotic treatment did not affect outcome. A thorough surgical technique directly influences early and late survival.

[Timing of reoperation of degenerated aortic and mitral bioprostheses]. / Zeitpunkt der Reoperation bei degenerierten aortalen und mitralen Bioprothesen.

Reoperative surgery for degenerated aortic and mitral valve bioprostheses has a considerable mortality. This study compares life expectancy, mode of failure and predictors for emergency reoperation and reoperative mortality between degenerated aortic and mitral bioprostheses. A total of 265 bioprosthetic valve patients, 172 aortic and 93 mitral patients, were followed to assess the time period between first and redo valve replacement. Mean life expectancy for aortic bioprostheses was 10.4 +/- 4.3 (2 to 28.6) years, whereas it was 10.0 +/- 3.7 (0.9 to 20) years for mitral bioprostheses (group M). Emergency reoperation had to be performed in 31/172 group A (18%) and 16/93 group M (17%) patients. In group A, the reoperative mortality was 5.2%; it was 1.4% for elective and 22.6% for emergency reoperation (p < 0.0001; OR = 20.3). Reoperative mortality in group M patients was 5.4% and did not differ between elective and emergency surgery. Group A patients who died at reoperation had higher transvalvular gradients before the first operation (p = 0.007), received smaller sized bioprostheses (p = 0.03) and had a higher incidence of coronary artery disease (p = 0.001) and pulmonary artery hypertension (p = 0.009) acquired during the interval. Endocarditis being the reason for primary surgery (p = 0.004), postoperative pneumonia after the first procedure (p = 0.005), pulmonary artery hypertension (p = 0.0004), later recurrence of symptoms of valve degeneration (p = 0.04), acute onset of bioprosthetic regurgitation (p = 0.00002) and a lower left ventricular ejection fraction (p = 0.03) were risk factor for emergency surgery. There were no predictors of reoperative mortality identified in mitral valve patients. The life expectancy of aortic and mitral bioprostheses is acceptable even in a relatively young patient population (mean age 46 +/- 13 in group A and 45 +/- 12 years in group M patients). Patients with degenerated aortic bioprostheses undergoing emergency reoperation have an extraordinary high reoperative mortality. They can be identified as patients who had a history of endocarditis and higher transvalvular gradients prior to the first operation, who received smaller sized bioprostheses and acquired coronary artery disease and pulmonary artery hypertension during the interval. Thus, emergency reoperation is preventable, increasing overall life expectancy of patients with bioprostheses. There were no risk factors for reoperative mortality identified in bioprosthetic mitral valve patients.

[Long-term results after surgery for acute aortic endocarditis]. / Langzeitresultate der chirurgischen Behandlung der akuten Aortenklappenendokarditis.

Late results after surgery for acute infectious aortic endocarditis using allografts are compared with those achieved with bioprostheses or mechanical heart valves. Cryopreserved allografts were used in 74 (22 %) and prosthetic heart valve in 262 out of 336 (78 %) patients presenting acute aortic endocarditis. Prosthetic (p = 0.001) and destructive endocarditis (p = 0.001) were more frequent in patients receiving allografts. Mean follow-up time was 6.6 ± 4 years (range, 3 to 28 years). The 30-daymortality was 19 % for allograft patients and 6 % for those receiving prosthetic heart valves (p = 0.002). Early reoperation, postoperative renal failure and sepsis did not differ between groups. After 20 years, actuarial survival was 60 % for mechanical heart valves, 44 % for bioprosthesis and 38 % for allografts (p = 0.003), reoperation was unnecessary in 52 % of mechanical heart valves and 10 % of bioprostheses and allografts (p = 0.0007). Acute infection at the time of operation (p = 0.0001), redo surgery (p = 0.0006), staphylococci (p = 0.0003), older age (p = 0.004) and mitral valve involvement (p = 0.004) were risk factors for late death, irrespective of preoperative antibiotic treatment and type of prosthesis used. A longer bypass and aortic cross-clamp time predicted early (p = 0.0001) and late survival (p = 0.0001), independently. Destructive aortic endocarditis has a poor long-term outcome irrespective of the use of allografts. Acute infection at the time of surgery predicted early and late death; however, surgery is indicated prior to secondary involvement of the mitral valve. The duration of preoperative antibiotic treatment did not affect outcome. A thorough surgical technique directly influences early and late survival.

[Timing of reoperation of degenerated aortic and mitral bioprostheses]. / Zeitpunkt der Reoperation bei degenerierten aortalen und mitralen Bioprothesen.

Reoperative surgery for degenerated aortic and mitral valve bioprostheses has a considerable mortality. This study compares life expectancy, mode of failure and predictors for emergency reoperation and reoperative mortality between degenerated aortic and mitral bioprostheses. A total of 265 bioprosthetic valve patients, 172 aortic and 93 mitral patients, were followed to assess the time period between first and redo valve replacement. Mean life expectancy for aortic bioprostheses was 10.4 ± 4.3 (2 to 28.6) years, whereas it was 10.0 ± 3.7 (0.9 to 20) years for mitral bioprostheses (group M). Emergency reoperation had to be performed in 31/172 group A (18 %) and 16/93 group M (17 %) patients. In group A, the reoperative mortality was 5.2 %; it was 1.4 % for elective and 22.6 % for emergency reoperation (p < 0.0001; OR = 20.3). Reoperative mortality in group M patients was 5.4 % and did not differ between elective and emergency surgery. Group A patients who died at reoperation had higher transvalvular gradients before the first operation (p = 0.007), received smaller sized bioprostheses (p = 0.03) and had a higher incidence of coronary artery disease (p = 0.001) and pulmonary artery hypertension (p = 0.009) acquired during the interval. Endocarditis being the reason for primary surgery (p = 0.004), postoperative pneumonia after the first procedure (p = 0.005), pulmonary artery hypertension (p = 0.0004), later recurrence of symptoms of valve degeneration (p = 0.04), acute onset of bioprosthetic regurgitation (p = 0.00002) and a lower left ventricular ejection fraction (p = 0.03) were risk factor for emergency surgery. There were no predictors of reoperative mortality identified in mitral valve patients. The life expectancy of aortic and mitral bioprostheses is acceptable even in a relatively young patient population (mean age 46 ± 13 in group A and 45 ± 12 years in group M patients). Patients with degenerated aortic bioprostheses undergoing emergency reoperation have an extraordinary high reoperative mortality. They can be identified as patients who had a history of endocarditis and higher transvalvular gradients prior to the first operation, who received smaller sized bioprostheses and acquired coronary artery disease and pulmonary artery hypertension during the interval. Thus, emergency reoperation is preventable, increasing overall life expectancy of patients with bioprostheses. There were no risk factors for reoperative mortality identified in bioprosthetic mitral valve patients.

Reoperative surgery for degenerated aortic bioprostheses: predictors for emergency surgery and reoperative mortality.

OBJECTIVE: The long-term outcome of patients with aortic bioprosthetic valves could be improved by decreasing the reoperative mortality rate. METHODS: Predictors of emergency reoperation and reoperative mortality were identified retrospectively in 172 patients who had the first bioprosthetic aortic valve replacement between 1975 and 1988 (mean age 46+/-13 years) and were subjected to replacement of the degenerated bioprostheses between 1978 and 1997 (mean age 56+/-14 years). Emergency reoperation had to be performed in 31 patients (18%). RESULTS: The operative mortality was 5.2% (9/172), 22.6% for emergency (odds ratio 11.17; 95%-confidence limit 4.33-28.85) and 1.4% for elective replacement of the degenerated aortic bioprosthesis (P<0.0001; OR=20.3). Patients who died at reoperation had higher transvalvular gradients before the primary aortic valve replacement (P=0.007), received smaller bioprostheses at the first operation (P=0.03), had later recurrence of symptoms after the first aortic valve replacement (P=0.04), a higher pre-reoperative New York Heart Association (NYHA) class (P=0.02), and a higher incidence of coronary artery disease (P=0.001) and pulmonary artery hypertension (P=0.009). Endocarditis before the primary aortic valve replacement (P=0.004), postoperative pneumonia at the first operation (P=0.005), pulmonary hypertension (P=0.0004) acquired during the interval, later recurrence of symptoms (P=0.04) after the first operation, a lower ejection fraction at the time of reoperation (P=0.03) and acute onset of bioprosthetic regurgitation (P=0.00002) were predictors for emergency surgery. Higher transvalvular gradients at the primary aortic valve replacement (P=0. 006), coronary artery disease (P=0.003) acquired during the interval, the need for concomitant coronary artery revascularization (P=0. 001), sex (P=0.02) and size (P=0.05) and type of the bioprostheses used (P=0.007) were incremental predictors for reoperative mortality which were independent of emergency surgery. CONCLUSIONS: Elective replacement of failed aortic bioprostheses is safe. Patients undergoing emergency reoperation have a considerably higher mortality. They can be identified by a history of native aortic valve endocarditis, higher transvalvular gradients at primary aortic valve replacement, smaller bioprostheses, and pulmonary hypertension or coronary artery disease acquired during the interval. A failing bioprosthesis must be replaced at its first sign of dysfunction.

Cyclosporine A and control of vascular tone in the human forearm: influence of post-transplant hypertension.

OBJECTIVE: The use of cyclosporine A after organ transplantation is associated with a high incidence of hypertension, but the underlying mechanisms for this process are not clear. We investigated the effects of blockade of basal release of endothelial nitric oxide and the effects of endothelium-independent and -dependent vasodilators and vasoconstrictors in patients treated with cyclosporine A after heart transplantation. DESIGN: We measured blood pressure and forearm blood flow responses to brachial artery infusions of NG-monomethyl-L-arginine (L-NMMA), sodium nitroprusside, acetylcholine, norepinephrine and vasodilating and vasoconstricting doses of endothelin-1 in eight patients early (< 3 months) and in 11 patients late (> 18 months) after transplantation. RESULTS: Diastolic blood pressure was higher late after transplantation, but calculated forearm vascular resistance was lower (P < 0.01). Thus, increased forearm vascular resistance does not contribute to the increase in blood pressure. The vasoconstrictor response to L-NMMA was similar in both groups but a reduced endothelium-dependent vasodilator response to acetylcholine was seen late after transplantation. However, impaired smooth muscle responsiveness to nitric oxide may have contributed to this finding, since the response to sodium nitroprusside tended to be reduced. Vasoconstrictor responses to norepinephrine and endothelin-1 were comparable but no vasodilation was seen with low doses of endothelin-1 late compared with early after transplantation (P < 0.05). CONCLUSIONS: The findings in the forearm circulation question the concept of generalized increases in vasoconstrictor responses or a disturbance of tonic, basal release nitric oxide in the pathogenesis of cyclosporine-A-induced hypertension. Although the forearm vasodilator responses to the stimulation of endothelial nitric oxide production and release by acetylcholine, and to low doses of endothelin-1, were impaired, these findings could be explained by the increase in blood pressure rather than cyclosporine A itself.

Preoperative predictors of recurrent atrial fibrillation late after successful mitral valve reconstruction.

OBJECTIVE: Late outcome after mitral valve repair was examined to define preoperative predictors of recurrent atrial fibrillation late after successful mitral valve reconstruction. METHODS: One hundred and eighty-nine patients, 112 with preoperative sinus rhythm and 72 with preoperative chronic or intermittent atrial fibrillation, were followed for 12.2 +/- 10 years after valve repair. Clinic, hemodynamic end echocardiographic data were entered into Cox-regression and Kaplan-Meyer analysis to assess predictors for recurrent atrial fibrillation late after successful mitral valve repair. RESULTS: Univariate and multivariate predictors for recurrent atrial fibrillation late after successful mitral valve reconstruction were preoperative atrial fibrillation (P = 0.0001), preoperative antiarrhythmic drug treatment (P = 0.005), heart rate (P = 0.01), left ventricular ejection fraction (P = 0.01) and increased left ventricular posterior wall thickness (P = 0.05). Patients > 57.5 years with a mean pulmonary artery pressure > or =23 mm Hg and a history of preoperative antiarrhythmic drug treatment had an odds ratio of 53.33 (95% confidence limits 6.12-464.54) for atrial fibrillation late after successful mitral valve repair. CONCLUSION: Older patients with a history of atrial fibrillation, antiarrhythmic treatment or an elevated pulmonary artery pressure may present atrial fibrillation late after successful mitral valve repair. They could be considered for combined mitral valve reconstruction and surgery for atrial fibrillation even though sinus rhythm is present preoperatively.

Prognosis of medically treated patients referred for cardiac transplantation.

OBJECTIVES: To assess prognosis and factors influencing survival of transplant candidates in whom continued medial therapy was recommended in comparison to that of immediately listed patients. METHODS: Retrospective analysis of clinical, echocardiographic and hemodynamic data as related to survival or listing for transplantation of medically treated transplant candidates. PATIENTS: 160 patients considered 'too well' for cardiac transplantation and 133 patients immediately listed for transplantation. RESULTS: Forty-one of the medically treated patients deteriorated clinically and were listed after 10.7+/-12.3 months after initial evaluation. Mid-term prognosis (2 years) of patients never listed was comparable to that of immediately listed patients (74% vs. 70%) but long-term prognosis (5 years) was worse (41% vs. 54%, p<0.001). Cardiothoracic ratio and pulmonary capillary wedge pressure were independent predictors of survival (multivariate analysis) in patients whose NYHA class and physical working capacity improved and cardiothoracic ratio decreased significantly after adjustment of medical therapy. CONCLUSIONS: Mid-term prognosis of selected patients considered 'too well' for transplantation is comparable to patients immediately listed. Lower left ventricular filling pressures, smaller hearts on chest X-ray on initial evaluation, and improvement of symptoms during follow up may identify a subgroup of patients who do well on optimized therapy.

Extradural sensory rhizotomy in the management of chronic lumbar radiculopathy: a minimum 2-year follow-up study.

STUDY DESIGN: Fifty-one consecutive patients who underwent extradural sensory rhizotomy for chronic radiculopathy after lumbar surgery were reviewed retrospectively. OBJECTIVES: To determine the effectiveness of sensory rhizotomy in the management of chronic radiculopathy in patients selected by extensive imaging techniques and selective nerve root sheath injections. SUMMARY OF BACKGROUND DATA: Results of more central ablative procedures for chronic benign pain problems have been disappointing, with variable reports of pain relief. METHODS: Fifty-one patients were reviewed. All patients underwent extensive evaluation to exclude reversible structural lesions, and all had the diagnosis of chronic radiculopathy confirmed by results of clinical and electrophysiologic examination. Selective nerve root sheath injections under fluoroscopic guidance confirmed the symptomatic nature of the segments. All blocks were repeated at least once. All patients underwent selective sensory rhizotomy or, in some cases, complete rhizotomy. After rhizotomy, 37 patients were available to be observed at selected time intervals for a minimum of 2 years. Clinical results were determined by the presence or absence of pain relief (visual analog scale), sensory and motor deficits, narcotic analgesic usage, and the patient's estimation of the effectiveness of the procedure. RESULTS: At 6 months after surgery, all 51 patients and the outcomes of their surgery were available for review. Fifty-five percent of patients rated were believed to have good or excellent outcomes, whereas the remainder had poor or failed outcomes. For the minimum 2-year follow-up period (range, 2-4.2 years), 37 patients were available for review. At final follow-up examination only 19% of the patients maintained good or excellent outcomes. CONCLUSIONS: The results of the rhizotomy procedures deteriorated over time. Possible reasons for the failure, other than temporal deterioration, were anatomic factors and lack of specificity of diagnostic techniques, specifically selective nerve root sheath injection. At this point rhizotomy cannot be recommended with any confidence whatsoever in the setting of chronic lumbar radiculopathy after lumbar surgery.

[Pharmacologic therapy of severe heart failure]. / Die medikamentöse Therapie der schweren Herzinsuffizienz.

Improvement of symptoms and, accordingly, quality of life, as well as prolongation of life, are the objectives of drug therapy in congestive heart failure patients. Diuretics are most effective in relieving symptoms related to congestion, and angiotensin converting enzyme inhibitors improve exercise capacity, reduce the incidence of decompensations and hence hospitalizations, and prolong life. Angiotensin type-1 receptor antagonists also seem to improve survival, while digoxin improves symptoms and morbidity but not survival in patients in sinus rhythm. The value of prophylactic antiarrhythmic therapy with amiodarone and oral anticoagulation in the presence of sinus rhythm is not established, and the role of newer dihydropyridine calcium antagonists and betablockers is also not precisely defined. These agents should only be considered in selected cases after careful consideration of potential advantages and risks, and should usually be used as an addition to established therapy. Better understanding of the pathophysiology of congestive heart failure will lead to the development of new treatment concepts, the clinical relevance of which will have to be tested in appropriately designed clinical trials.

A taxonomy of chronic pain syndromes.

This article has had as its purpose the delineation of the complexity of the production of pain on an organic basis as opposed to any psychological amplification. The issues addressed apply directly to the problem of spinal pain. Classical nociception arising in the structures of the spine thus would include the application of mechanical and chemical stimuli to muscles, ligaments, apophyseal joint capsules, bone, and other structures with adequate innervation, particularly the anterior dura and its extensions. Disease and injury productive of direct nociception are well understood sources of spinal pain. Less well understood, but of at least equal importance in the spinal pain problem, are the activities within the central nervous system that control the transfer of nociceptive information to the higher centers. These activities account for some of the variability known to occur in the experience of pain. Further, the fact that the nervous system changes its activities in response to chronic pain, particularly that arising from damaged neural elements, is of paramount importance in understanding how chronic pain syndromes differ so greatly from simple nociceptive events. Insidious deafferentation ongoing in spinal nerve roots subject to chronic compression and fibrosis offers a fertile field for research into the origin of permanent pain in patients in whom application of accepted therapies does not result in relief. All of this material must be considered by the clinician who is challenged with analyzing spinal pain problems in patients.

Fusion rates in multilevel cervical spondylosis comparing allograft fibula with autograft fibula in 126 patients.

Surgical fusion results are presented from a retrospective study of 126 consecutive multilevel discectomy and vertebrectomy cases for spondylosis to evaluate fusion rates using autograft and allograft fibula strut graft for reconstruction. The nonunion rate was high in both groups: 27% of the autograft group and 41% of the allograft group. The nonunion rate increased with increasing numbers of motion segments fused. Age and sex were not significant factors.

Postoperative infections in spinal implants. Classification and analysis--a multicenter study.

A multicenter study was undertaken to analyze postoperative wound infections after posterior spinal instrumentation and fusion. The infection rate of these procedures has been documented in multiple reports. From these results, a classification scheme was developed that can guide therapy and determine the populations at risk. The patients were categorized according to two parameters, the first being the severity or type of infection, and the second being the host response or physiologic classification of the patient. This classification scheme is based on the clinical staging system for adult osteomyelitis developed by Cierny. The severity of infection is divided into three groups. Group 1 is a single-organism infection, either superficial or deep. Group 2 is a multiple-organism, deep infection. Group 3 is multiple organisms with myonecrosis. The host response, likewise, is divided into three classes. Class A is a host with normal systemic defenses, metabolic capabilities, and vascularity. Class B patients demonstrate local or multiple systemic diseases, including cigarette smoking. Class C requires an immunocompromised or severely malnourished host. Our data have demonstrated that single organisms, Group 1, generally can be dealt with by single irrigation and debridement, and closure over suction drainage tubes without the use of an inflow-irrigation system. The Group 2 patients, with multiple organisms and deep infection, required an average of three irrigation debridements. They have a higher percentage of successful closures with closed inflow-outflow suction irrigation systems when compared to simple suction drainage systems without constant inflow irrigation. Multiple-organism infections with myonecrosis, Group 3, are exceedingly difficult to manage, and portend a poor outcome. Patients without normal host defenses, Classes B and C, are at high risk for developing postoperative wound infection. Specifically, this study demonstrated that cigarette smoking may be a significant risk factor.

The failed posterior lumbar interbody fusion.

The problems presented by unsuccessful posterior lumbar interbody fusion (PLIF) have not been addressed. The cases of 12 patients who presented with failed PLIF were reviewed. Five patients were male and seven female (age range, 24-50 years; mean age, 40 years). All patients underwent at least one PLIF; many had undergone other procedures. A total of 37 procedures had been performed on the 12 patients. Chronic radiculopathy was present in all patients, as detected with electromyographic or nerve conduction velocity examination. At the time of reconstructive surgery, in the 11 patients in whom the canal was explored, all had extensive epidural fibrosis. Nine of the 12 patients had pseudarthrosis of the previous PLIF. Four patients had evidence of motion segment dysfunction at nearby levels: two had positive discograms adjacent to the PLIFs; one developed a facet syndrome at L5-S1, caudal to an L4-5 PLIF; and one demonstrated frank segmental instability at L2-3, cranial to a previous PLIF at L3-4. Twelve patients underwent a total of 22 procedures after referral. Eleven patients initially underwent decompression and fusion, and one patient underwent a sympathectomy. Seven patients underwent an additional 10 procedures, including repeat decompression, repair of pseudarthrosis, and implantation of an epidural analgesic pump system. After all surgical treatment, five patients rated their pain as improved. Seven patients were thought to have a solid fusion. The presence of a solid fusion did not correlate with satisfactory relief of pain (chi-square). Continued extremity pain was the predominant complaint of all the patients. Two shortcomings of the PLIF were evident.(ABSTRACT TRUNCATED AT 250 WORDS)

Reconstruction of failed lumbar surgery with narrow AO DCP plates for spinal arthrodesis.

Forty-five patients underwent surgical reconstruction with transpedicular fixation of the lumbar spine with narrow AO DCP plates. Preoperatively, all patients underwent spinal imaging with either magnetic resonance imaging, computed tomography, or myelogram as well as provocative discography to determine the location and the number of symptomatic segments. The minimum follow-up in this series was 2 years. The determination of solid posterior fusion in the presence of plate instrumentation was difficult. The patients in the series were classified as having 1) solid fusion; 2) radiographic flaws within the posterolateral fusion without implant failure; or 3) frank pseudarthrosis with implant failure. Thirty-six (80%) of the patients had a solid fusion, 9 of whom required an additional anterior interbody fusion to obtain symptom control. Twenty percent of the patients in the series had radiographic evidence of reabsorption without implant failure. Four patients in the series (8.8%) had screw breakage, three of which required anterior interbody fusions. The highest rate of reabsorption and pseudarthrosis implant failure was in the 12 patients who had three-level instrumentation; 33% of these patients required anterior interbody fusion to obtain a solid arthrodesis. The average preoperative pain scale was 8.9, and the average postoperative pain scale was a 3.3. Twenty-two patients in the series were cigarette smokers and had a slightly lower fusion rate than non-smokers. They did, however, have a higher use of narcotics after surgery. Forty percent of the patients in this series continued to have radiculopathy after their reconstruction. This study demonstrates the utility of transpedicular fixation in salvage lumbar surgery in obtaining a solid arthrodesis with a beneficial clinical result. Anterior interbody fusions are highly successful in the management of pseudarthrosis and implant failure after transpedicular instrumentation.

Reconstruction of the lumbar spine using AO DCP plate internal fixation.

Augmentation of lumbar spine fusion with internal fixation using pedicle screw systems has gained wide currency because it offers rigid stabilization to foster fusion healing. The AO DCP plate has been employed in Europe as a spinal implant with pedicle fixation using 6.5 mm, full-threaded cancellous bone screws with success. This report details the experience of using this device for lumbar spine fusion in a series of 46 North American patients with a mean follow-up of 1.25 years (range 1-2.5 years). Thirty-one patients had had prior lumbar spine surgery with poor outcomes, and 15 had had no prior surgery. All were treated surgically for lumbar degenerative disease with canal decompression, internal fixation with AO plates, and fusion with autologous bone grafting posterolaterally. Complications included two early and one delayed wound infection; five cases of screw loosening; three cases of screw breakage; and three cases of screw impingement upon a nerve. Results of surgery in 17 patients with failed interbody fusion included good to excellent pain relief in 59%, and solid fusion in 76%. In 14 patients with failed posterior surgery the good to excellent pain relief rate was 79%, and the fusion rate was 86%. In 15 patients undergoing primary surgery there was 89% good to excellent pain relief and a solid fusion rate of 87%. The benefits accruing from augmentation of the fusion with internal fixation using AO DCP plates are positive and justify its continued use. Complications encountered in the early experience have been significantly reduced in subsequent series, indicating the existence of a "learning curve" effect which would mandate specific training of spinal surgeons in the technique.