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Biomedical subjects

B S Allen

Publications and source records attributed to B S Allen.

At least 19 recordsLinked to original sources
PubMed2001

Antibiotic susceptibilities among recent clinical isolates of Haemophilus influenzae and Moraxella catarrhalis from fifteen countries.

Between July 1998 and July 1999, 3,060 Haemophilus influenzae and 1,486 Moraxella catarrhalis strains were isolated in 31 centers in 15 countries in order to determine their antimicrobial susceptibilities and the presence of beta-lactamase production in Haemophilus influenzae. Overall 17.1% of the Haemophilus influenzae isolates were beta-lactamase positive, while more than 95% were susceptible to amoxicillin/clavulanate, cefaclor, loracarbef, cefuroxime, azithromycin and ciprofloxacin. Eleven (0.3%) isolates were beta-lactamase positive and ampicillin resistant and 7 (0.2%) isolates were ciprofloxacin resistant. The minimum inhibitory concentrations for 90% of the isolates tested were lowest for ciprofloxacin (0.03) and highest for cefprozil (8) against Moraxella catarrhalis.

Anti-Bacterial Agents↗
PubMed2001

Antimicrobial susceptibilities of clinical isolates of Haemophilus influenzae and Moraxella catarrhalis collected during 1999-2000 from 13 countries.

OBJECTIVE: To determine antimicrobial activity against Haemophilus influenzae and Moraxella catarrhalis. METHODS: A central laboratory performed NCCLS susceptibility testing for all isolates and beta-lactamase and capsular serotype determinations for H. influenzae. RESULTS: A total of 2712 H. influenzae and 1079 M. catarrhalis were collected. H. influenzae susceptibilities were >90% for amoxicillin/clavulanate, cefaclor, loracarbef, cefprozil, cefuroxime, ciprofloxacin, azithromycin and clarithromycin and were <80% for trimethoprim/sulfamethoxazole and ampicillin. 19.3% were beta-lactamase positive. The most common serotype was type-b (5.6%); 86.1% were nontypeable. M. catarrhalis had MIC90 within therapeutic range for all antimicrobials except ampicillin. CONCLUSION: The conclusion of the study is that antimicrobials, except ampicillin and trimethoprim/sulfamethoxazole, remain good empiric choices against H. influenzae and M. catarrhalis.

Adolescent↗
PubMed2001

Pediatric myocardial protection: an overview.

This article describes the experimental infrastructure and subsequent successful clinical application of a comprehensive bypass and cardioplegic strategy that limits intraoperative injury and improves postoperative outcomes in pediatric patients. The infant heart is at high risk of damage from poor protection because of preoperative hypertrophy, cyanosis, and ischemia. The background factors of vulnerability to damage caused by cyanosis and ischemia are discussed, together with studies of the infrastructure of strategies to use normoxia versus hyperoxia as bypass starts, white blood cell filtration, warm induction and reperfusion with substrate enhancements, multidose blood cardioplegia, and an integrated approach to allow ischemia only when vision is needed in pediatric surgeries. Data on cardioplegic management, including reducing calcium, increasing magnesium, and reducing perfusion pressure are shown, as used during this technique. These principles were applied to a consecutive series of 567 patients at the Heart Institute for Children and University of Illinois hospital over a 2-year period. Included also were 72 patients with hypoplastic left heart over a 4-year period with this myocardial management strategy. Application of these concepts may improve the safety of protection in infant hearts.

Animals↗
PubMed2001

Hypoxia, reoxygenation and the role of systemic leukodepletion in pediatric heart surgery.

As cardiopulmonary bypass (CPB) in infants and neonates is becoming more frequent, the technical performance of these operations for congenital heart disease has made significant progress. However, little research has been carried out into the conduct of CBP in producing myocardial and pulmonary dysfunction. Postoperative organ dysfunction is a problem, particularly for cyanotic infants. This paper examines the experimental and clinical experience of injury brought about by abrupt reoxygenation of the hypoxic, or cyanotic, heart. The modalities of gradual reoxygenation and leukodepletion in limiting this injury are examined, leading to the conclusion that injury can be reduced and possibly ameliorated by changes in intraoperative management during CBP in children with cyanotic disease.

Animals↗
PubMed2000

The role of cardioplegia induction temperature and amino acid enrichment in neonatal myocardial protection.

BACKGROUND: Warm cardioplegic induction improves the ischemically "stressed" adult heart. However, it is rarely used in infants, despite the fact that many newborn hearts are stressed by other factors such as hypoxia. The need for amino acids as well as their mechanism of action has also not been studied. METHODS: We first assessed the role of cardioplegic induction temperature in 10 nonhypoxic neonatal piglets undergoing 70 minutes of multidose blood cardioplegic arrest. Five piglets (group 1) received a cold (4 degrees C) induction, and 5 (group 2) a warm (37 degrees C) induction. Twenty-six other piglets underwent ventilator hypoxia (fraction of inspired oxygen, 8% to 10%) for 60 minutes before cardiopulmonary bypass (stress). Six piglets (group 3) then underwent 70 minutes of cardiopulmonary bypass without ischemia (hypoxia controls), and 20 underwent 70 minutes of cardioplegic arrest. Five of these (group 4) received cold cardioplegic induction, and 15 received warm induction; in 5 of these (group 5), the warm cardioplegic solution contained amino acids, in 5 others (group 6), it was unsupplemented, and in the remaining 5 (group 7), nitroglycerin was added to determine the role of vasodilation. Myocardial function was assessed by pressure-volume loops (expressed as a percent of control), and coronary vascular resistance was measured with cardioplegic infusions. RESULTS: In nonhypoxic (normal) piglets, cold (group 1) and warm (group 2) induction completely preserved systolic function (end-systolic elastance, 100% versus 104%) and preload recruitable stroke work (100% versus 102%), with minimal increase in diastolic compliance (162% versus 156%). Hypoxia-reoxygenation alone (group 3) depressed systolic function (end-systolic elastance, 51%+/-2%) and preload recruitable stroke work (54%+/-3%), and raised diastolic stiffness (260%+/-15%). The detrimental effects of reoxygenation persisted (unchanged from reoxygenation alone) with cold induction (group 4) or warm induction without amino acids (groups 6 and 7). In contrast, warm induction with amino acids (group 5) restored systolic function (end-systolic elastance, 105%+/-3%; p < 0.001 versus groups 3, 4, 6, and 7) and preload recruitable stroke work (103%+/-2%; p < 0.001 versus groups 3, 4, 6, and 7), and decreased diastolic stiffness (154%+/-7%; p < 0.001 versus groups 3, 4, 6, and 7). However, there was no difference in myocardial oxygen consumption in hypoxic hearts receiving a warm induction (6.9 versus 6.5 versus 7.3 mL/g per 5 minutes) (groups 5, 6, 7), and coronary vascular resistance was lowest with nitroglycerin (group 7). CONCLUSIONS: Cardioplegic induction can be given either warm or cold in nonhypoxic neonatal hearts. In contrast, only warm induction with amino acids repairs the hypoxic injury, but the primary mechanism of action is not related to increased metabolic activity or vasodilation.

Adenosine↗
PubMed2000

Reducing postischemic reperfusion damage in neonates using a terminal warm substrate-enriched blood cardioplegic reperfusate.

BACKGROUND: In adult cardiac operations, a warm cardioplegic reperfusate ("hot shot") before removing the aortic cross-clamp improves postbypass myocardial function and metabolic recovery. This modality, however, is rarely used in infants, despite the fact that postbypass cardiac dysfunction remains problematic, especially in cyanotic ("stressed") patients. METHODS: To produce stress, 15 neonatal piglets underwent 60 minutes of ventilator hypoxia (fraction of inspired oxygen, 8% to 10%). All piglets then received similar protection with multidose cold blood cardioplegic solution during 70 minutes of arrest and were separated into three groups to examine the role of a warm reperfusate as well as possible augmentation by aspartate and glutamate enrichment. In 5 piglets (group 1), the cross-clamp was simply removed; in 5 (group 2), an unsupplemented warm blood cardioplegic reperfusate was given; and in 5 (group 3), the warm reperfusate was enriched with aspartate and glutamate. Myocardial function was assessed using pressure-volume loops and expressed as a percentage of control. RESULTS: Compared with hearts receiving reperfusion with unmodified blood (group 1), a warm unsupplemented cardioplegic reperfusate (group 2) slightly improved systolic contractility (end-systolic elastance, 41% versus 50%; p < 0.05 versus group 1) and preload recruitable stroke work (41% versus 52%; p < 0.05 versus group 1), reduced diastolic stiffness (263% versus 245%; p < 0.05 versus group 1), and increased adenosine triphosphate (10.7 versus 11.9 microg/g tissue, p < 0.05 versus group 1). However, if aspartate and glutamate was included in the warm reperfusate (group 3), there was complete recovery of systolic function (end-systolic elastance, 105%+/-3%; p < 0.001 versus all groups) and preload recruitable stroke work (103%+/-2%; p < 0.001 versus all groups), a minimal rise in diastolic stiffness (154%+/-7%; p < 0.001 versus all groups), and preservation of adenosine triphosphate (15.5+/-0.5 microg/g; p < 0.001 versus all groups). CONCLUSIONS: A warm cardioplegic reperfusate helps reduce the reperfusion injury, resulting in improved myocardial function and metabolic recovery in hypoxic (stressed) neonatal hearts, and this effect is maximized if the reperfusate is enriched with aspartate and glutamate, which completely preserves myocardial function.

Adenosine Triphosphate↗
PubMed2000

Lowering reperfusion pressure reduces the injury after pulmonary ischemia.

BACKGROUND: Controlled reperfusion with a modified solution limits pulmonary injury following ischemia. Our initial studies infused this modified reperfusate at a pressure of 40 to 50 mm Hg to insure distribution. However, perhaps a lower pressure, which is closer to the normal physiologic pressure in the lung, would improve results by decreasing sheer stress. METHODS: Fifteen adult pigs underwent 2 hours of lung ischemia by clamping the left bronchus and pulmonary artery. Five (group 1) then underwent uncontrolled reperfusion by removing the vascular clamps and allowing unmodified blood to reperfuse the lung at a pulmonary artery pressure of 20 to 30 mm Hg. The other 10 pigs underwent controlled reperfusion by mixing blood from the femoral artery with a crystalloid solution, and infusing this modified reperfusate into the ischemic lung through the pulmonary artery for 10 minutes before removing the arterial clamp. In 5 (group 2), the modified solution was infused at a pressure of 40 to 50 mm Hg, and in 5 (group 3) 20 to 30 mm Hg. Lung function was assessed 60 minutes after reperfusion and expressed as percentage of control. RESULTS: Compared to uncontrolled reperfusion (group 1), controlled reperfusion at a pressure of 40 to 50 mm Hg (group 2) significantly improved postreperfusion pulmonary compliance (77% versus 86%; p<0.001 versus group 1), and arterial/alveolar ratio (a/A) ratio (27% versus 52%; p<0.001 versus group 1); as well as decreased pulmonary vascular resistance (PVR) (198% versus 154%; p<0.001 versus group 1), lung water (84.3% versus 83.5%; p<0.001 versus group 1), and myeloperoxidase (0.35 versus 0.23 optical density/min/mg protein). Reducing the pressure of the modified reperfusate to 20 to 30 mm Hg further improved postreperfusion compliance (92%+/-1%; p<0.001 versus groups 1 and 2) and a/A ratio (76%+/-1%; p<0.001 versus groups 1 and 2); and lowered PVR (133%+/-2%; p<0.001 versus groups 1 and 2), lung water (82.7%+/-0.1%; p<0.001 versus groups 1 and 2), and myeloperoxidase (0.16%+/-0.01%; p<0.001 versus groups 1 and 2). CONCLUSIONS: After 2 hours of pulmonary ischemia, a severe lung injury occurs following uncontrolled reperfusion, controlled reperfusion with a modified solution reduces this reperfusion injury, and lowering the pressure of the modified reperfusate to more physiologic levels (20 to 30 mm Hg) further reduces the reperfusion injury improving pulmonary function.

Animals↗
PubMed2000

Modification of the subclavian patch aortoplasty for repair of aortic coarctation in neonates and infants.

BACKGROUND: Coarctation repair in neonates or small infants, using a subclavian patch, has a relatively high risk of restenosis, especially if complicated by the presence of a short subclavian artery or long coarctation segment. We introduce a technical modification that facilitates the use of a subclavian flap, and decreases the restenosis rate in this subgroup of patients. It consists of a side-to-side transverse aortic anastomosis at the level of the coarctation, which widens the coarctation segment, shortens the isthmus, and pulls the distal end of the aortotomy proximally, allowing a tension-free subclavian flap aortoplasty. METHODS: Fifty-three consecutive neonates or infants less than 18 weeks old, with complex coarctation, underwent repair using this technique. Mean age was 26+/-3 days and 36 patients (68%) were less than 28 days old. Weights ranged from 1.4 to 6.4 kg (mean 3.4+/-0.2 kg), and 26 patients had other cardiac anomalies. Preoperative gradient by Doppler measurement ranged from 25 to 90 mm Hg (mean 49+/-2 mm Hg). RESULTS: Mean aortic cross-clamp time was 27+/-1 minutes (range 19 to 34 minutes). There were no deaths or surgical complications. Follow-up echocardiogram 4 to 52 months postoperatively (mean 25+/-2 months) demonstrated no significant pressure gradient (less than 20 mm Hg) in 51 of 53 patients (96%), and a significant gradient in 2 patients (4%), which was subsequently corrected with balloon angioplasty. CONCLUSIONS: The technical modification described shortens the isthmus, and thus allows for a longer aortotomy distal to the area of coarctation resulting in a tension-free repair especially in patients with a short subclavian artery. It also widens the area of coarctation, and as a result leads to a lower early recoarctation rate in this high-risk group. With increasing emphasis on the need for a longer aortotomy to prevent restenosis, this modification will have increasing application, especially in the neonatal population.

Aortic Coarctation↗
PubMed2000

In vitro activities of LY333328 and comparative agents against nosocomial gram-positive pathogens collected in a 1997 global surveillance study.

The in vitro activity of LY333328 was evaluated for 1,479 nosocomial gram-positive pathogens isolated in 12 countries during 1997. LY333328 MICs at which 90% of the isolates tested were inhibited for Enterococcus faecalis (n = 351), Enterococcus faecium (n = 100), Staphylococcus aureus (n = 593), coagulase-negative Staphylococcus species (n = 325), and Streptococcus pneumoniae (n = 110) were 1, 1, 2, 2, and 0.015 microg/ml, respectively. LY333328 demonstrated potent activity against isolates of vancomycin-resistant enterococci, oxacillin-resistant staphylococci, and penicillin-resistant pneumococci.

Anti-Bacterial Agents↗
PubMed2000

Assessment of the susceptibility of Streptococcus pneumoniae to cefaclor and loracarbef in 13 countries.

Between July 1998 and July 1999, 2,644 clinical isolates of Streptococcus pneumoniae were collected from 27 study centers in 13 countries and their susceptibilities to penicillin, cefaclor and loracarbef were determined by E-test" (AB BIODISK, Solna, Sweden). Overall, 96.3% of isolates were penicillin-susceptible (79.8%) or -intermediate (16.6%) (MIC, < or = 1 microg/ml). Rates of penicillin-resistant S. pneumoniae isolation varied widely and were highest in the study centers tested in New Zealand (10.9%), Canada (10.0%), Mexico (9.1%) and the United States (5.1%). Low rates of penicillin-resistance were found in the study centers tested in Russia (0%), Turkey (0%), Brazil (0.5%), Germany (0.6%), Philippines (1.6%), Italy (2.1%), United Kingdom (2.3%), Australia (3.0%) and Poland (3.1%). Using recently published NCCLS interpretative breakpoints (M100-S10, 2000), 87.2% (median) of all isolates tested were cefaclor-susceptible and 87.8% (median) of all isolates tested were loracarbef-susceptible. Of the penicillin-susceptible S. pneumoniae isolates, 99.5% were susceptible to both cefaclor and loracarbef. Susceptibility to cefaclor and loracarbef was also retained by 30.8% and 32.9% of penicillin-intermediate isolates, respectively. These findings are in contrast to recent publications reporting lower cefaclor and loracarbef activities using non-validated interpretative criteria. In conclusion, rates of penicillin resistance among recent clinical isolates of pneumococci remain low in many centers worldwide. Cefaclor and loracarbef demonstrated excellent in vitro activity against recent clinical isolates of penicillin-susceptible and many isolates of penicillin-intermediate S. pneumoniae.

Cefaclor↗
PubMed2000

Oral antimicrobial susceptibilities of Streptococcus pyogenes recently isolated in five countries.

Between July 1998 and July 1999 1050 clinical isolates of Streptococcus pyogenes were collected from 11 study centres in five countries. Isolates were shipped to a co-ordinating laboratory for NCCLS specified broth microdilution susceptibility testing for penicillin, cefaclor, azithromycin, clarithromycin, erythromycin and roxithromycin. All 1050 isolates of S. pyogenes tested were susceptible to penicillin (MIC < or = 0.12 microgram/ml) and cefaclor (MIC < or = 0.25 microgram/ml). Azithromycin, clarithromycin and erythromycin resistance rates were 15.9%, 15.4% and 15.8%, respectively. MIC90S for penicillin, cefaclor, azithromycin, clarithromycin, erythromycin, and roxithromycin were 0.015, 0.12, > 4, 8, > 1 and 16 micrograms/ml, respectively. Macrolide (erythromycin) resistance rates were highest in study centres in Italy (31.0%) and Spain (26.6%). Lower macrolide resistance rates were identified in study centres in Turkey (4.8%), France (3.8%), and Sweden (3.7%). In conclusion, the isolates of S. pyogenes tested were universally susceptible to beta-lactam antibiotics such as penicillin and cefaclor, while resistance to macrolides was significant and ranged from 3.2% to 31%.

Anti-Bacterial Agents↗
PubMed1999

Superiority of magnesium cardioplegia in neonatal myocardial protection.

BACKGROUND: We have shown that magnesium can offset the detrimental effects of normocalcemic cardioplegia in hypoxic neonatal hearts. It is not known, however, whether magnesium offers any additional benefit when used in conjunction with hypocalcemic cardioplegia. METHODS: Twenty neonatal piglets underwent 60 minutes of ventilator hypoxia (FiO2 8% to 10%) followed by 20 minutes of normothermic ischemia on cardiopulmonary bypass (hypoxic-ischemic stress). They then underwent 70 minutes of multidose blood cardioplegic arrest. Five (Group 1), received a hypocalcemic (Ca+2 0.2 to 0.4 mM/L) cardiologic solution without magnesium, whereas in 10, magnesium was added at either a low dose (5 to 6 mEq/L, Group 2) or high dose (10 to 12 mEq/L, Group 3). In the last 5 (Group 4), magnesium (10 to 12 mEq/L) was added to a normocalcemic cardioplegic solution. Function was assessed using pressure volume loops and expressed as percentage of control. RESULTS: Compared to hypocalcemia cardioplegic solution without magnesium (Group 1), both high- and low-dose magnesium enrichment (Groups 2 and 3) improved myocardial protection resulting in complete return of systolic (40% vs 101% vs 102%) (p < 0.001 vs Groups 2 and 3) and global myocardial function (39% vs 102% vs 101%) (p < 0.001 vs Groups 2 and 3), and reduced diastolic stiffness (267% vs 158% vs 154%) (p < 0.001 vs Groups 2 and 3). Conversely, even high-dose magnesium supplementation could not offset the detrimental effects of normocalcemic cardioplegia resulting in depressed systolic (End Systolic Elastance [EES] 41%+/-1%) (p < 0.001 vs Groups 2 and 3) and global myocardial function (40%+/-1%) (p < 0.001 vs Groups 2 and 3), and a marked rise in diastolic stiffness (258%+/-5%) (p < 0.001 vs Groups 2 and 3). Hypocalcemic magnesium cardioplegia has now been used successfully in 247 adult and pediatric patients. CONCLUSIONS: Magnesium enrichment of hypocalcemic cardioplegic solutions improves myocardial protection resulting in complete functional preservation. However, magnesium cannot prevent the detrimental effects of normocalcemic cardioplegia when the heart is severely stressed. This study, therefore, strongly supports using both a hypocalcemic cardioplegic solution and magnesium supplementation as their benefits are additive.

Adenosine Diphosphate↗
PubMed1999

Dose dependency of L-arginine in neonatal myocardial protection: the nitric oxide paradox.

OBJECTIVES: Recent experimental studies have suggested that enriching cardioplegic solution with L-arginine improves myocardial protection by increasing nitric oxide production. Nitric oxide, however, also generates the toxic oxygen-derived free radical peroxynitrite; thus these beneficial effects may be dose dependent, especially in vulnerable (stressed) hearts. METHODS: Fifteen neonatal piglets underwent 60 minutes of ventilator hypoxia (inspired oxygen fraction 8%-10%) followed by 20 minutes of normothermic ischemia on cardiopulmonary bypass (stress). They were then protected for 70 minutes with multiple doses of blood cardioplegic solution. In 5 (group 1), the cardioplegic solution contained no L-arginine, in 5 (group 2), it was enriched with a 4 mmol/L concentration of L-arginine, and in 5 (group 3), a 10 mmol/L concentration of L-arginine. Myocardial function was assessed by means of pressure volume loops and expressed as a percentage of control, and coronary vascular resistance and conjugated diene production were measured during infusions of cardioplegic solution. RESULTS: Compared with the protection afforded by blood cardioplegic solution without L-arginine (group 1), the addition of a 4 mmol/L concentration of L-arginine (group 2) significantly improved myocardial protection, resulting in complete return of systolic function (end-systolic elastance 38% vs 100%; P <.001 vs 4 mmol/L L-arginine) and preload recruitable stroke work (40% vs 100%; P <. 001 vs 4 mmol/L L-arginine); minimal increase in diastolic stiffness (239% vs 158%; P <.001 vs 4 mmol/L L-arginine); and lower coronary vascular resistance, conjugated diene production, and myeloperoxidase activity (P <.001 vs 4 mmol/L L-arginine in each case). Conversely, supplementing the cardioplegic solution with a 10 mmol/L dose of L-arginine (group 3) negated these beneficial effects, resulting in depressed systolic function (end-systolic elastance 41% +/- 2%; P <.001 vs 4 mmol/L L-arginine) and preload recruitable stroke work (40% +/- 2%; P <.001 vs 4 mmol/L L-arginine); increased diastolic stiffness (246% +/- 7%; P <.001 vs 4 mmol/L L-arginine); and higher conjugated diene production, myeloperoxidase activity, and coronary vascular resistance (P <.001 vs 4 mmol/L L-arginine in each case). CONCLUSIONS: Enriching cardioplegic solution with a 4 mmol/L concentration of L-arginine significantly improves myocardial protection by reducing oxygen-derived free radical formation by white blood cells, thus preserving vascular and myocardial function. However, these beneficial effects are dose dependent because 10 mmol/L concentrations of L-arginine increase oxygen-derived free radical production, resulting in vascular and myocardial dysfunction.

Animals↗
PubMed1999

L-arginine, prostaglandin, and white cell filtration equally improve myocardial protection in stressed neonatal hearts.

OBJECTIVES: L-Arginine may improve cardioplegic protection by increasing nitric oxide production. However, L-arginine may also be detrimental because it generates the free radical peroxynitrite. It would, therefore, be advantageous if the benefits of L-arginine could be achieved by another means. METHODS: Twenty neonatal piglets underwent 60 minutes of ventilator hypoxia (inspired oxygen fraction 8%-10%) followed by 20 minutes of ischemia on cardiopulmonary bypass (stress) and were then protected for 70 minutes with multiple doses of blood cardioplegic solution. In 5 piglets (group 1), the cardioplegic solution was not modified; in 5 (group 2), low-dose L-arginine (4 mmol/L) was added; in 5 (group 3), prostaglandin E(1) (alprostadil, 4 microgram/L) was added; and in 5 (group 4), the cardioplegic solution was passed through a leukodepleting filter. Myocardial function was assessed by pressure volume loops and expressed as percentage of control, and coronary vascular resistance was measured with each cardioplegic infusion. RESULTS: Unmodified blood cardioplegic solution (group 1) was unable to protect the severely stressed myocardium, resulting in depressed systolic function (39% +/- 1%) and preload recruitable stroke work (40% +/- 1%), increased diastolic stiffness (239% +/- 3%), and high conjugated diene production, myeloperoxidase activity, and coronary vascular resistance. In contrast, cardioplegic solutions modified with L-arginine, prostaglandin E(1), or leukodepletion, resuscitated the stressed myocardium, resulting in complete return of systolic function (100% vs 101% vs 101%; P <.001 vs group 1) and preload recruitable stroke work (100% vs 101% vs 101%; P <.001 vs group 1), minimal increase in diastolic stiffness (160% vs 162% vs 160%; P <. 001 vs group 1), and lowered conjugated diene production, myeloperoxidase activity, and coronary vascular resistance (P <.001 vs group 1 for each). CONCLUSIONS: (1) Unmodified blood cardioplegic solution is unable to protect the severely stressed myocardium. (2) L-Arginine, prostaglandin E(1), and leukocyte filtration all improve myocardial protection equally and appear to work by limiting a white blood cell-mediated injury. This reduces oxygen-derived free radical formation, maintains vascular function, and restores functional recovery. Since L-arginine may be detrimental, surgeons should consider using prostaglandin E(1) and/or a leukocyte filter instead.

Alprostadil↗
PubMed1999

Cefaclor af versus amoxycillin/clavulanate in acute bacterial exacerbations of chronic bronchitis: a randomised multicentre study.

Cefaclor and amoxycillin/clavulanate are active against Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis and Staphylococcus aureus--pathogens commonly associated with acute exacerbations of chronic bronchitis (AECB). This randomised, parallel-group, single-blind, multicentre study investigated the comparative efficacy and safety of 7-day treatment regimens of cefaclor AF (750 mg b.d. [n = 73]) and amoxycillin/clavulanate (875/125 mg b.d. [n = 72]) in AECB. A favourable clinical response was obtained in 95.9% of patients on cefaclor AF and 97.2% of patients on amoxycillin/clavulanate. There were no statistically significant differences between the groups for improvement in clinical response measured by pulmonary peak expiratory flow (PPEF), or for common symptoms associated with AECB. Both agents were well tolerated, with no statistically significant differences in overall safety; however, nausea and vomiting, and abdominal pain, the most frequently occurring adverse events in the amoxycillin/clavulanate group, were not reported in the cefaclor group. In conclusion, cefaclor AF and amoxycillin/clavulanate have similar efficacy and safety profiles in the treatment of AECB.

Adult↗
PubMed1998

Combined coronary bypass and liver transplantation: technical considerations.

Combined coronary artery bypass grafting and orthotopic liver transplantation was carried out successfully in a 58-year-old man with angina pectoris and end-stage liver disease. To date, only 2 similar cases have been documented worldwide whereby the transplantation was performed either during cardiopulmonary bypass or with femoral-to-axillary venovenous bypass initiated at the termination of cardiopulmonary bypass. In this report we describe our experience with a simplified one-exposure approach for the combined operation using cardiopulmonary bypass in tandem with percutaneous femoral-to-right atrial venovenous bypass.

Angina Pectoris↗
PubMed1998

Controlled reperfusion prevents pulmonary injury after 24 hours of lung preservation.

BACKGROUND: Posttransplantation lung reperfusion injury continues to be a major problem. We have shown that controlling the initial period of reperfusion limits this injury after 2 hours of warm lung ischemia. The effectiveness of this modality, however, is unknown after longer periods of cold ischemia, which more closely mimics the clinical situation. METHODS: After baseline measurements, 10 pigs had the left lung flushed with a modified Euro-Collins solution, explanted, stored at 4 degrees C for 24 hours, and transplanted into 10 other pigs. Five (group 1) underwent uncontrolled reperfusion created by removal of the vascular clamps after implantation of the new left lung, mimicking the clinical situation. The other five (group 2) underwent controlled reperfusion, which we performed by taking blood from the femoral artery, mixing it with a crystalloid solution (using a mixer heater) to make the blood hyperosmolar, alkalotic, and substrate-enriched, and pumping it through a leukocyte-depleting filter into the transplanted lung for 10 minutes at a pressure of 20 to 30 mm Hg before removing the pulmonary artery clamp. The right pulmonary artery and bronchus were then ligated, and left lung function was assessed each hour for 4 hours and compared with baseline. RESULTS: Controlled reperfusion (group 2) minimized the reperfusion injury, preserving posttransplant pulmonary compliance (92% +/- 1% versus 68% +/- 1%; p < 0.001), reducing the rise in pulmonary vascular resistance (27% +/- 2% versus 166% +/- 3%; p < 0.001), improving oxygenation (PO2, 425 +/- 14 versus 82 +/- 11 mm Hg; p < 0.001), and lowering myeloperoxidase activity (0.22 +/- 0.02 versus 0.45 +/- 0.02 deltaOD/mg protein per minute; p < 0.001) and tissue edema (83.0% +/- 0.3% versus 84.9% +/- 0.3%; p < 0.001) compared with uncontrolled reperfusion, which resulted in an injury so severe that 3 of 5 pigs died before the 4-hour measurements. CONCLUSIONS: After 24 hours of cold ischemia uncontrolled reperfusion results in a severe pulmonary reperfusion injury. This injury is almost completely avoided by controlling the composition (modified solution and white blood cell filter) and conditions (pressure) of the reperfusion. Because this experiment mimics the clinical situation, it suggests surgeons should begin to use this modality to limit reperfusion injury after lung transplantation.

Animals↗