Accelerometry May be Superior to EMG for Early Evaluation of Vocal Cord Function After Nerve Injury in a Pig Model.

OBJECTIVE: Vocal cord (VC) movement has been demonstrated by the use of accelerometry (ACC) to decrease in parallel with the electromyographic amplitude (EMG) during ongoing traction injury to the recurrent laryngeal nerve (RLN). When RLN function recovers, discrepancies between EMG and VC movement have been reported in clinical and experimental studies. The present study was conducted to clarify the actual relationship between EMG and VC movement measured by ACC during nerve recovery. METHODS: EMG obtained by continuous nerve monitoring (C-IONM) was compared with ACC during traction injury to the RLN, and throughout 40-min nerve recovery. A three-axis linear accelerometer probe was attached to the VC, and ACC data were registered as described. Traction damage was applied to the RLN until there was a 70% amplitude decrease from baseline EMG, or until loss of signal (LOS), that is, EMG values ≤100 µV. RESULTS: Thirty-two RLN from 16 immature pigs were studied. Correlation between EMG and ACC were calculated during nerve injury and nerve recovery. The mean correlations were for the 70% and LOS group from start to end of traction: 0.82 (±0.17) and 0.87 (±0.17), respectively. Corresponding correlation coefficients during 40-min recovery was 0.50 (±0.48) in the 70% group and 0.53 (±0.33) in the LOS group. CONCLUSION: There is a high correlation between EMG and VC movement during nerve injury, and a moderate correlation during early nerve recovery. EMG recovery after RLN injury ensures sufficient VC function as assessed by ACC. LEVEL OF EVIDENCE: N/A Laryngoscope, 134:1485-1491, 2024.

Fluid filtration and vascular compliance during cardiopulmonary bypass: effects of two volatile anesthetics.

BACKGROUND: As intraoperative fluid accumulation may negatively impact post-operative organ function, strategies minimizing edema generation should be sought for. During general anesthesia, isoflurane in contrast to sevoflurane has been associated with increased fluid extravasation and edema generation. In this study, we tested sevoflurane against isoflurane with focus on vascular compliance and fluid shifts in an experimental cardiopulmonary bypass (CPB) model. METHODS: Sixteen pigs underwent 120 min of cardiopulmonary bypass with isoflurane or sevoflurane anesthesia. Net fluid balance, plasma volume, serum-electrolytes, serum-albumin, serum-protein, colloid osmotic pressures in plasma and interstitial fluid, hematocrit levels, and total tissue water content were recorded. Intra-abdominal and intracranial pressures were measured directly, and fluid extravasation rates were calculated. RESULTS: Fluid extravasation rate increased dramatically in both groups during initiation of cardiopulmonary bypass, with no group differences. The animals of the sevoflurane group needed significantly more fluid supplementation to maintain a constant reservoir volume in the CPB circuit during bypass. Plasma volumes prior to bypass were 56.5 ± 7.9 ml/kg (mean ± SD) and 58.7 ± 3.8 ml/kg in the isoflurane group and sevoflurane group, respectively. During bypass, plasma volumes in the isoflurane group decreased about 25%, and remained significantly lowered when compared to the sevoflurane group, where the values remained stable. CONCLUSIONS: No differences in fluid extravasation rates were observed between sevoflurane and isoflurane. The increased net fluid balance in the sevoflurane group during cardiopulmonary bypass was not associated with edema generation. Plasma volume was retained in the sevoflurane group, in contrast to the isoflurane group.

Dynamic evaluation of fluid shifts during normothermic and hypothermic cardiopulmonary bypass in piglets.

BACKGROUND: Edema, generalized overhydration and organ dysfunction commonly occur in patients undergoing open-heart surgery using cardiopulmonary bypass (CPB) and induced hypothermia. Activation of inflammatory reactions induced by contact between blood and foreign surfaces are commonly held responsible for the disturbances of fluid balance ("capillary leak syndrome"). We used an online technique to determine fluid shifts between the intravascular and the interstitial space during normothermic and hypothermic CPB. METHODS: Piglets were placed on CPB (fixed pump flow) via thoracotomy in general anesthesia. In the normothermic group (n=7), the core temperature was kept at 38 degrees C prior to and during 2 h on CPB, whereas in the hypothermic group (n=7) temperature was lowered to 28 degrees C during bypass. The CPB circuit was primed with acetated Ringer's solution. The blood level in the CPB circuit reservoir was held constant during bypass. Ringer's solution was added when fluid substitution was needed (falling blood level in the reservoir). In addition to invasive hemodynamic monitoring, fluid input and losses were accurately recorded. Inflammatory mediators or markers were not measured in this study. RESULTS: Cardiac output, s-electrolytes and arterial blood gases were similar in the two groups in the pre-bypass period. At start of CPB the blood level in the machine reservoir fell markedly in both groups, necessitating fluid supplementation and leading to a markedly reduced hematocrit. This extra fluid need was transient in the normothermic group, but persisted in the hypothermic animals. After 2 h of CPB the hypothermic animals had received 7 times more fluid as compared to the normothermic pigs. CONCLUSION: We found strong indications for a greater fluid extravasation during hypothermic CPB compared with normothermic CPB. The experimental model using the CPB-circuit reservoir as a fluid gauge gives us the opportunity to study further fluid volume shifts, its causes and potential ways to optimize fluid therapy protocols.

Complications and death after surgical treatment of small bowel obstruction: A 35-year institutional experience.

OBJECTIVE: To study factors influencing complications and death after operations for small bowel obstruction (SBO) using multifactorial statistical methods. SUMMARY BACKGROUND DATA: Death after surgery for SBO is believed to be influenced by factors such as old age, comorbidities, bowel gangrene, and delay in treatment. No studies have been reported in which adverse factors related to death and complications have been systematically investigated with modern statistical methods. METHODS: The authors studied retrospectively 877 patients who underwent 1,007 operations for SBO from 1961 to 1995. Patients with paralytic ileus, intussusception, and abdominal cancer were excluded. Odds ratios for death, complications, postoperative hospital stay, and strangulation were calculated by means of logistic regression analyses. RESULTS: Death and complication rates decreased during the study period. Old age, comorbidity, nonviable strangulation, and a treatment delay of more than 24 hours were significantly associated with an increased death rate. The rate of nonviable strangulation increased markedly with patient age. Major factors increasing the complication rate were old age, comorbidity, a treatment delay of more than 24 hours, and the need for repeat surgery. CONCLUSION: Death and complication rates after SBO decreased from 1961 to 1995. Major factors influencing the rates were age, comorbidity, nonviable strangulation, and treatment delay. Nonviable strangulation was more common in old patients.

p53 mutations in defined structural and functional domains are related to poor clinical outcome in non-small cell lung cancer patients.

The prognostic value of p53 status in non-small cell lung cancer has been investigated in 148 patients with clinical stage I-IIIB disease. Tumor tissues were examined for mutations in exons 4-9, with emphasis on defined structural and functional domains. Eighty-four mutations were detected in 83 (54%) of the patients. Eighty-eight percent of the mutations were within exons 5-8, and 12% of the mutations were within exons 4 and 9. Missense mutations occurred in 67% of the tumors, and 30% were null mutations (10% stop mutations, 15% frameshift mutations, and 5% splice site mutations). Patients with mutations in p53 had a significantly higher risk for lung cancer-related death and for death from all causes than those with wild-type p53 [hazard ratio (HR) = 2.09 and 95% confidence interval (CI) = 1.20-3.64 and HR = 1.69 and 95% CI = 1.06-2.70, respectively]. Mutations in p53 related to even still poorer lung cancer-related prognosis were found at the following locations: (a) exon 8 (HR = 3.5; 95% CI, 1.59-7.71)]; (b) the structural domains L2 + L3 (HR = 2.36; 95% CI, 1.18-4.74), and (c) codons involved in zinc binding (HR = 11.7; 95% CI, 3.56-38.69). Together, the biologically functional group of severe flexible mutants (codons 172, 173, 175, 176, 179, 181, 238, 245, and 267) and severe contact mutants (248, 282) were significantly related to shorter lung cancer-related survival (HR = 4.16; 95% CI, 1.93-8.97). Squamous cell carcinoma was the dominant histological type in tumors involved in poor prognosis in exon 8 (HR = 3.19; 95% CI, 1.07-9.45). These results indicate that mutations in defined structural and functional domains of p53 may be useful molecular biological markers for prognosis and treatment strategy in non-small cell lung cancer patients.

Surgical treatment of spontaneous pneumothorax by wedge resection without pleurodesis or pleurectomy.

OBJECTIVE: Evaluation of wedge resection of the lung without pleurodesis or pleurectomy as a method of surgical treatment for spontaneous pneumothorax in terms of complications, recurrence rate and postoperative complaints. METHODS: Retrospective study of 132 operations for spontaneous pneumothorax in 120 patients (84 men and 36 women: mean age 34 years, range 14-77) performed between 1974 and 1993. The mean observation time was 84 months (range 6-229) and a 100% follow-up rate of all survivors (97%) was achieved. RESULTS: The indications for surgery were recurrent pneumothorax (52%), persisting air leak during first episode (45%), or hemothorax (3%). Perioperative findings were single bullous disease (86%), 2-3 bullae (6%), diffuse bullous disease (5%) and no bullous disease in 3% of the cases. The overall complication rate was 16% (30-day mortality 1%, reoperation for postoperative bleeding 2%, bronchopneumonia 8%, new pneumothorax during hospital stay 5%). The late recurrence rate (operated lung) was 5%. All recurrences were successfully treated by drainage (n = 3), exsufflation (n = 1) or observation only (n = 3). Reoperation was not necessary. Thirty-seven percent of the patients had postoperative complaints which they associated with the operation. CONCLUSION: Lung resection without pleurodesis or pleurectomy is a simple, safe and effective method of the surgical treatment of spontaneous pneumothorax in terms of complications and recurrence rate in patients with limited bullous disease.

Morbidity, ability to swallow, and survival, after oesophagectomy for cancer of the oesophagus and cardia.

OBJECTIVE: To study survival, morbidity, and ability to swallow, after oesophagectomy for cancer of the oesophagus and cardia. DESIGN: Prospective open study. SETTING: University hospital, Norway. SUBJECTS: 83 patients, 38 with squamous cell carcinoma and 45 with adenocarcinoma of the oesophagus and cardia. INTERVENTIONS: Transhiatal (n = 51) and transthoracic (n = 32) oesophagectomy. Oesophageal replacement was by either stomach (n = 80) or colon (n = 3). Cervical anastomosis was used in all but 2. MAIN OUTCOME MEASURES: Early and late morbidity and mortality, length of stay in intensive care unit and in hospital, and survival analysis. RESULTS: 30 Day and in hospital mortality were 0 and 4% for transhiatal, and 6% and 9% for transthoracic, oesophagectomy. Complications included recurrent nerve palsy (n = 7), anastomotic leaks (n = 5), and chylothorax (n = 4). 17 Patients (22%) needed dilatations for stenosis of the anastomosis, and 71 (85%) of the patients left hospital within four weeks of operation. Survival analysis showed a 5 year survival rate of 33% for patients with adenocarcinoma operated on for cure and a 2 year survival of 28% for patients with squamous cell carcinoma. CONCLUSIONS: Oesophagectomy for cure is worthwhile as some patients are cured and most of the remainder have prolonged relief of their dysphagia. Palliative resections should not be done in patients with distant metastases or invasion of adjacent organs by the tumour because of long stay in hospital, appreciable morbidity, and short life expectancy.

Dilation of the internal mammary artery by external and intraluminal papaverine application.

Three methods for prevention of perioperative spasm of the internal mammary artery were compared in 78 patients undergoing coronary artery bypass grafting. In group 1, internal mammary artery pedicles were divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (1.5 mg/ml). In group 2, as in group 1 but before clamping, 2 ml of heparinized blood with 1.5 mg/ml papaverine added was injected into the vessel lumen. In group 3 treatment was as in group 2, but heparinized blood with papaverine was injected a second time just before extracorporeal bypass was begun. In a univariate analysis free flow from dilated internal mammary arteries was not significantly different among the groups (group 1, 58 ml/min; group 2, 82 ml/min; group 3, 68 ml/min; p < 0.1). When free flow from dilated internal mammary arteries was the dependent variable in a regression analysis, the use of intraluminal papaverine, high blood pressure during flow measurement, and high initial blood flow were predictors of high flow (all p < 0.01). Morphometric measurements on the resected distal portion of the dilated internal mammary arteries disclosed less folding of the internal elastic lamina and a larger luminal area in groups 2 and 3 compared with respective findings in group 1 (1.21 mm2 and 1.42 mm2 versus 0.77 mm2; p < 0.02). Mechanical vessel wall injury occurred in 8 of 52 internal mammary arteries treated with intraluminal papaverine. Intraluminal papaverine solution injected once or twice in addition to external papaverine exposure therefore provides a better blood flow rate and distal dilation than mere submersion in papaverine solution, but at a considerable risk of mechanical wall injury.

Long-term clinical performance of a central venous oxygen saturation sensor for rate adaptive cardiac pacing.

Rate adaptive ventricular pacemakers using central venous oxygen saturation (O2Sat) to control the pacing rate have been implanted in 14 patients (mean age 71 years), with a mean follow-up period of 44 months (range 2-63 months). In eight patients the pacemakers were replaced due to signs of battery depletion after an implant duration of 39-58 months. During bicycle exercise testing the O2Sat decreased on average from 61% +/- 4% at rest to 36% +/- 4% (P < 0.0001) at peak exercise, and the maximum pacing rate was 122 +/- 5 beats/min. The time delay until the O2Sat had dropped 10%, 65%, and 90% of the total reduction during exercise was 4.8 +/- 0.9 seconds, 39.8 +/- 3.8 seconds, and 71.3 +/- 7.5 seconds, respectively. The O2Sat decreased 9.4% +/- 2% (P < 0.005) from resting supine to resting sitting. Oxygen breathing increased the telemetered O2Sat from the pacemaker by 8.4% +/- 1% (P < 0.001). During follow-up the O2Sats were relatively stable in 50% of the patients, but demonstrated significant fluctuations in the others. At 1-year invasive follow-up O2Sat measured by the pacemaker decreased 22% +/- 2%, and in blood samples from the right ventricle 22% +/- 2% from rest to 3 minutes exercise at 25 watts. There was a significant correlation between O2Sat measured by the pacemaker and in blood samples from right ventricle (n = 105; r = 0.73; P < 0.001). In two patients the O2Sat dropped significantly during pneumonia. In another patient episodes of angina pectoris was associated with low O2Sat and a concomitant fast pacing rate.

p53 mutations in lung tumors: relationship to putative susceptibility markers for cancer.

We have screened 108 non-small cell lung tumors for mutational alterations in the p53 gene (exons 5 through 8) using polymerase chain reaction and denaturing gel electrophoresis techniques. Thirty-four cases (32%) had aberrant band migrations. The following DNA-sequencing step confirmed the mutations in all these samples. Seventy-six % of the mutations were found at G:C base pairs. Of all the mutations found, 29% were GC to AT, 29% GC to TA, 15% AT to GC, 12% GC to CG, and 3% AT to CG. The other mutations (12%) were deletions or insertions of one base pair. The frequency of p53 mutations among heavy smokers was higher than in nonsmokers (P = 0.047; odds ratio, 6.75; 95% confidence interval, 0.80-57). We examined p53 mutations in relation to genotypes of GSTmu1 and H-ras1. Our data showed that nearly all heavy smokers with transversion mutations were homozygous for the GSTmu1 null allele (10 of 11). The frequency of such mutations was significantly higher for patients with two null alleles (10 of 25) than for those with at least one allele intact (1 of 18) (P = 0.011; odds ratio, 11.33; 95% confidence interval, 1.29-99.3). This study indicated that rare alleles at the variable number of tandem repeats region flanking the H-ras protooncogene are negatively associated to the presence of p53 mutations in the tumors (P = 0.009).

Postoperative Doppler echocardiographic evaluation in different sizes of Medtronic-Hall, Biocor and Carpentier-Edwards S.A.V. prosthetic aortic valves.

Doppler echocardiography was performed on 108 patients 4-15 days after implantation of a Medtronic-Hall, Biocor or Carpentier-Edwards S.A.V. prosthetic aortic valve because of aortic stenosis. Significant correlation was found between the in vitro (maker-declared) and the Doppler-estimated effective prosthetic valve orifice area (r = 0.70, p < 0.01). Doppler-estimated prosthetic valve orifice area, but not transprosthetic blood velocities, discriminated between different sizes of Medtronic-Hall and Biocor valves. The effective orifice area in these valves was 57% of the in vitro area, but in Carpentier-Edwards valves it was only 43%. Transprosthetic blood velocity was inversely related to orifice area in men, but not in women, who also had longer duration of systole and better preservation of systolic left ventricular function. The data suggest that the effective prosthetic valve areas found in patients are significantly smaller than the experimental in vitro areas. Prosthesis size and type, anatomic and hemodynamic variables and gender are important in Doppler estimation of effective valve area.

Perforated peptic ulcer over 56 years. Time trends in patients and disease characteristics.

Perforated gastroduodenal ulcer was studied in 1483 patients in the Bergen area during the years 1935-90 to discover time trends in age and sex, disease characteristics, treatment, and outcome. The male:female ratio fell from 10:1 to 1.5:1, median age increased from 41 to 62 years. Most perforations were found in the duodenum in 1935-64, and in the pyloric and praepyloric area in 1965-90. There was a 10% occurrence of gastric ulcers throughout the study period. Ulcer site was related to age (more gastric and less duodenal perforations with increasing age) and sex (more pyloric and less duodenal ulcers among women). There were twice as many perforations in the evening compared with the early morning. The diurnal variation was more pronounced for duodenal and pyloric than for gastric and praepyloric perforations. Circadian and seasonal variation of ulcer perforation did not change during the 56 years studied. Treatment delay increased from median five hours to median nine hours. Infective complications and mortality fell with the introduction of antibiotics around 1950. General complications has increased in recent years because of the increase of elderly patients. Among patients who died, the proportion with associated disease rose from 27 to 85% during the study period.

Prognostic significance of p53 protein expression and DNA ploidy in surgically treated non-small cell lung carcinomas.

A series of 112 patients operated for non-small cell lung cancer was analyzed retrospectively. Nuclear suspensions were prepared from formalin-fixed, paraffin-embedded biopsies, and DNA content was measured simultaneously with p53 expression using flow cytometry. The expression of p53 protein was determined by the monoclonal antibody PAb 1801, which recognizes both wild-type (normal) and mutated forms of p53. By the level of p53 expression, four patient groups were statistically defined. Patients in the two groups with no detectable and extremely high p53 expression had a significantly better prognosis than patients in the two groups with moderately increased p53 expression. By logistic regression, p53 expression was found to be the single best predictor of 5 year survival. Patient age and tumor stage were less important prognostic factors. No difference in 5 year survival was observed between diploid and aneuploid tumors. We conclude that p53 is a useful prognostic predictor in low stage non-small cell lung carcinoma using the monoclonal antibody PAb 1801. The applicability of this antibody to archival material in flow cytometric analysis should allow a broad range of tumor types to be analyzed with respect to the prognostic significance of p53 overexpression.

[Treatment of ventricular tachyarrhythmias with an implantable pacemaker-cardioverter-defibrillator]. / Behandling av ventrikulaere takyarytmier med implanterbar pacemaker-kardioverter-defibrillator.

During the period from November 1989 to January 1992, 17 patients with ventricular tachyarrhythmias received an implantable pacemaker-cardioverter-defibrillator. The material consists of three female and 14 male patients with an age range of 13-66 years, mean 50.8 +/- 16.6 years. 13 patients had coronary artery disease, one cardiomyopathy, one a myocarditis sequela and two primary rhythm disorder. Four patients received epicardial and 13 endocardial electrode systems. The observation period varied from 4-30 months (april 1992), mean 15.2 +/- 8.8 months. 11 out of 17 patients (65%) experienced one or more episodes of tachyarrhythmias which was treated successfully with overdrive pacing (ramp or burst), cardioversion or defibrillation. One patient died of heart failure after an observation period of 13 months. His pacemaker-cardioverter-defibrillator had been activated more than 100 times. Two children, 13 and 15 years, were treated successfully for ventricular fibrillation four and five months after implantation of the device. The actual one year survival is 100%. Assuming that therapy with a device had not taken place, and that the six patients who experienced episodes of ventricular fibrillation died, the hypothetical probability of survival would have been 62.1 +/- 12.3%.

Dilation of the internal mammary artery by external papaverine application to the pedicle--an improved method.

Spasm of the internal mammary artery (IMA) during coronary bypass grafting may cause inadequate graft flow and makes accurate placement of sutures difficult. In addition, IMAs with poor intraoperative flow rates are more likely to occlude. In this study three methods for spasm prevention were compared in 51 patients undergoing coronary bypass surgery. In group 1, IMA pedicles were covered with a sponge soaked with papaverine solution (0.8 mg/ml of papaverine in 0.9% saline) and left intact distally, thus allowing continuous blood flow until used for bypass. In group 2, the IMAs were divided and clamped distally and the pedicle tucked into a papaverine-soaked sponge. In group 3, the IMAs were also divided distally, clamped, and placed under the upper sternum submerged in papaverine solution (0.8 mg/ml) inside a surgical glove. Free flow from the IMA was higher in group 3 than in groups 1 and 2 (60 ml/min vs. 44 and 30, respectively, P < 0.03). Morphometric measurements disclosed a larger luminal area and less folding of the internal elastic lamina in group 3 compared with groups 1 and 2 (0.73 mm2 vs 0.33 and 0.37, respectively, P < 0.03). Submersion in papaverine solution thus provides better procurement of IMA grafts than storage of the pedicle in a papaverine-soaked sponge.

Quantitation of biological tumor markers (p53, c-myc, Ki-67 and DNA ploidy) by multiparameter flow cytometry in non-small-cell lung cancer.

Fifteen primary non-small-cell lung carcinomas (8 adenocarcinomas and 7 squamous-cell carcinomas) were analyzed by multiparameter flow cytometry for their expression of p53 and c-myc proteins. In addition, the fraction of cells staining with the proliferation-associated antibody Ki-67 and DNA ploidy was determined. These 4 biological markers were analyzed in parallel samples from a single-cell suspension made from fresh, frozen biopsies. Thus, the internal relationship between these markers within each tumor-cell population was established. Three different anti-p53 antibodies were used: PAb 421, PAb 1801 and PAb 240. All 15 tumors were p53-positive with the antibodies PAb 1801 and PAb 240, whereas only 9 were positive as judged by the antibody PAb 421. This indicates that the choice of p53 antibody is not irrelevant. Ten tumors were c-myc-positive; 7 of these were adenocarcinomas. The c-myc-positive tumors had a significantly higher level of p53 expression, judged by PAb 1801 and PAb 240, than c-myc-negative tumors. For PAb 421, there was no difference. We did not find any correlation between Ki-67 staining and expression of p53 and c-myc proteins, either with DNA ploidy, S-phase fraction or histological type. Our study indicates that there might be an association between accumulation of p53 protein and c-myc over-expression in non-small-cell lung cancer, and that this in particular might apply to adenocarcinomas. Furthermore, we show that multiparameter flow cytometry is a powerful tool in the study of the relationship between different markers in a cell population.

Allele diversity of the H-ras-1 variable number of tandem repeats in Norwegian lung cancer patients.

We have examined restriction fragment length polymorphisms of the H-ras-1 gene in germ-line DNA from 214 lung cancer patients and 309 unaffected controls. When DNA samples were digested with MspI/HpaII, Southern blot analysis revealed at least 22 different alleles, grouped according to their frequencies as common, intermediate, and rare. The frequency of rare alleles in lung cancer patients (16/428) is significantly different (p = 0.002) from that in the control group (5/618). Individuals with rare alleles were found to be at 4.7-fold greater risk of lung cancer than those with no rare alleles.

Long term results after Nissen fundoplication and Belsey Mark IV operation in patients with reflux oesophagitis and stricture.

This retrospective study was undertaken to compare long term results of Nissen fundoplication and the Belsey Mark IV repair in patients with reflux oesophagitis and stricture between 1972 and 1987. 105 patients were operated on for reflux oesophagitis, and 43 of the patients had stricture. There was one postoperative death (after a Belsey Mark IV repair). The cumulative recurrence rate after the Nissen operation was 9%, all recurrences of oesophagitis occurring within the first two years. The cumulative recurrence after the Belsey repair was 37%. Only 15 of 32 patients treated with Nissen fundoplication for stricture needed dilatation after operation, and then only during the first two years. "Gas-bloat" occurred in 18% of the patients treated with Nissen fundoplication. We conclude that the Nissen fundoplication is a good operation for patients with severe reflux oesophagitis and for those with peptic strictures of the oesophagus. The Belsey Mark IV repair, however, cannot be recommended for patients with strictures.

Relationship between morphological signs of cell injury in myocardial ischaemia.

Morphological signs of severe ischaemic injury are well known. However, we still lack knowledge about how indices of milder injuries are related on a cellular level. In a previous study we have reported on the sequence of alterations across the border zone in cat hearts subjected to 3 h of coronary occlusion. In the present study, which elaborates that study, we have examined the relationship between morphological variables in serial sections of 220 myocytes within the border zone. In cells with intact sarcolemma and no chromatin changes, the fractional volume of cytoplasm has a bimodal distribution indicating cells with and without oedema. Whereas cells with focal disruptions of the sarcolemma have a moderate oedema, usually localized submembranously, cells with extensive sarcolemmal fragmentation have an extensive oedema. A mild oedema is seen before other signs of severe cell injury, even though more extensive oedema is closely associated with sarcolemmal fragmentation. The fractional volume of mitochondria was smaller, whereas the fractional volume of lipid droplets was larger in cells with oedema than in cells without oedema.

Respiratory gas exchange during treadmill exercise testing: reproducibility and comparison of different exercise protocols.

Ten subjects performed 4 maximal exercise tests to evaluate reproducibility and effects of treadmill inclination on submaximal and maximal oxygen consumption. They performed a standard Bruce protocol twice, and 1 protocol with progressive speed increase with constant, or without, inclination. At maximal exercise there was no significant difference between the protocols in oxygen consumption, respiratory gas exchange ratio, minute ventilation, plasma lactate, serum potassium or heart rate. Exercise time and treadmill distance were shorter than Bruce protocol with inclination, and considerably prolonged without. Reproducibility for Bruce protocol was good for group comparison of oxygen consumption throughout exercise. The individual variations for oxygen consumption were small at maximal exercise, but were considerable at rest and at the lowest exercise steps, this was slightly improved by analysing longer sampling time. Thus, measurement of oxygen consumption is reliable for group analysis, but interpretation must be careful in individuals unless maximal exercise is obtained. Treadmill inclination may be adjusted according to individual preferences.