Sitting pressure and perfusion of buttock skin in paraplegic and tetraplegic patients, and in healthy subjects: a comparative study.

The distribution of sitting pressure and ability to respond with reactive hyperaemia were studied in a group of paraplegic and tetraplegic patients (n = 8) with spinal cord lesions and healthy controls (n = 10) using a pressure sensitive plate and laser Doppler perfusion imager. The results show that the mean sitting pressure of the patients was 9.9 N/cm2 (left) and 11.7 N/cm2 (right) compared with 3.5 N/cm2 (left) and 3.6 N/cm2 (right) in controls. The differences were significant on both the left (p < 0.01) and right (p < 0.05) sides. The maximum pressure in patients was 42.9 N/cm2 (left) and 48.7 N/cm2 (right), and in controls 12.0 N/cm2 (left) and 12.9 (right) (p < 0.01). Both groups showed a reduction in skin perfusion in the seat area during sitting compared with unloaded resting, and in the controls it was significantly increased (p < 0.001 on both sides) during the reactive hyperaemic phase immediately after sitting. Compared with the preload values, the patients showed a similar but slightly weaker picture significant on the right side (p < 0.05), but not on the left. The hyperaemia was not uniformly distributed, but occurred where the pressure was greater than 2 N/cm2. There was no correlation between the amount of reactive hyperaemia and absolute values of sitting pressures. We conclude that tetraplegic and paraplegic patients have significantly higher sitting pressures than normal controls, and that the hyperaemic response in the buttock region in the upright position after pressure load is slightly weaker in the patients, which could be of importance for the development of decubitus ulcers.     

Perfusion of the skin of the buttocks in paraplegic and tetraplegic patients, and in healthy subjects after a short and long load.

In patients with spinal cord injuries (n=8) and healthy controls (n=8) the hyperaemic response in the buttock skin after sitting on a hard surface was studied using a laser Doppler perfusion imager. They sat for three minutes (short load), or 15 minutes (long load). An exponential mathematical function was used to compare the mean perfusion during the observed interval. The results showed that preloading perfusion is significantly higher among patients than healthy subjects. In both groups, the microcirculation of the skin increased significantly after loading, and peak perfusion was significantly lower after the short load. The mean perfusion was higher among the patients after both loadings, which suggests that there was stronger ischaemic provocation. The main outcome was that there was a dose-response relation between duration of loading and intensity of reactive hyperaemia, and that patients with spinal cord injuries have greater perfusion before and after loading than healthy controls.     

Common femoral artery volume flow in peripheral vascular disease

Common femoral artery volume flow was measured at rest and during postocclusive reactive hyperaemia in 80 normal subjects and 67 patients with radiological evidence of occlusive peripheral vascular disease. At rest, means(s.d.) common femoral artery volume flow in normal subjects (344(135) ml/min) and all patients with peripheral vascular disease (401(168) ml/min) was not significantly different. During postocclusive reactive hyperaemia, mean(s.d.) peak flow was significantly higher in normal subjects (1951(438) ml/min) than in patients with peripheral vascular disease (996(457) ml/min) (P less than 0.01). Common femoral artery volume flow in patients with critical ischaemia and intermittent claudication did not differ at rest but mean(s.d.) peak flow in patients with critical ischaemia (697(276) ml/min) was significantly lower than in claudicants (1131(447) ml/min) (P less than 0.01). Mean(s.d.) resting common femoral artery volume flow in limbs with femoropopliteal disease (457(185) ml/min) was significantly greater than that in limbs with occlusion of the aortoiliac segment (308(130) ml/min) (P less than 0.01). However, this difference did not persist during postocclusive reactive hyperaemia. A hyperaemic index, calculated from the hyperaemic responses to below knee and whole limb ischaemia, was used to quantify segmental perfusion during postocclusive reactive hyperaemia. The mean(s.d.) value in normal subjects, 46(9) per cent, and in those with aortoiliac disease, 52(12) per cent, indicated approximately equal perfusion of the above and below knee limb segments. In those with femoropopliteal disease the mean(s.d.) hyperaemic index was 17(13) per cent, revealing relative hypoperfusion of the below knee segment.     

Evaluation of posttraumatic vasospasm, hyperaemia, and autoregulation by transcranial colour-coded duplex sonography

Serial transcranial colour-coded duplex sonography (TCCS) was performed on 24 adult patients with severe head injury (GCS 8 or less). Flow velocities were obtained from the middle cerebral artery (MCA) and extracranial internal carotid artery (EICA). An autoregulation study was done using the transient hyperaemic response test, evidence of vasospasm (V-MCA greater than 100 cm/s and Lindegaard ratio more than 3) was found in nine patients (37%). Two of these developed non-contusion-related infarction and two others contusion-related infarction. This was significant (p < 0.05). Vasospasm started around day 2, reaching maximum around day 4 and persisting until the second week. Vasospasm was significantly associated with a poor outcome (p < 0.05). There was no correlation between the extent of SAH as seen on CT and vasospasm. Evidence of hyperaemia were observed in two patients (8%) and impaired autoregulation in seven patients (29%). Impaired autoregulation was significantly associated with development of hyperaemia (p < 0.05). TCCS studies permit a non-invasive evaluation of cerebral haemodynamics that will help in the management of head injured patients.     

Unstable baseline blood pressure in chronic tetraplegia

STUDY DESIGN: Case-control. OBJECTIVE: Tetraplegic patients are subject to episodes of autonomic dysreflexia and postural hypotension. It is suggested that these patients sustain, in addition, unstable baseline blood pressure (BP) that is independent of symptoms and body position. METHODS: BP monitoring was conducted in 10 tetraplegic patients, motor and sensory complete (American Spinal Injury Association (ASIA) A) (Group A), and five paraplegic at T8-T10 levels, ASIA A (Group B). A SpaceLabs automatically inflating pneumatic cuff recorded arm pressures at 10-30 min intervals in the daytime, sitting position and at 30 min intervals in the night-time, recumbent position. Group mean arterial pressure (MAP) and MAP standard deviation (MAP variation) for sitting and recumbent positions were compared. RESULTS: Sitting the MAP for Group A was less than that of Group B; 87+/-9 versus 108+/-7 mmHg, P<0.01. However, MAP variability for Group A was greater than for Group B; 17+/-4 (20% of MAP) versus 13+/-2 mmHg (12% of MAP), P=0.04. In the recumbent position, the MAP for Group A was similar to that for Group B; 87+/-13 versus 97+/-7 mmHg, P=0.16. However, MAP variability for Group A remained higher than for Group B; 13+/-3 (20% of MAP) versus 8+/-2 mmHg (8% of MAP), P=0.02. CONCLUSION: Tetraplegic patients demonstrate unstable BP in either the sitting or recumbent position compared with low thoracic paraplegic patients.     

Laser Doppler flowmetry in evaluation of skin post-ischaemic reactive hyperaemia. A study in healthy volunteers and atherosclerotic patients

Laser Doppler flowmetry (LDF) was used to evaluate skin post-ischaemic reactive hyperaemia. Four groups of subjects were examined: healthy young and elderly controls (groups A and B) and patients with intermittent claudication or critical ischaemia (groups C and D). The occlusion tourniquet was placed just proximal to the patella, and measurements were performed on the toe pulp (study 1) and leg skin (study 2). The hyperaemic response on both pulp and leg skin was delayed, diminished and prolonged in claudicators compared with controls. On the toe pulp most patients with critical ischaemia had no hyperaemic response at all, indicating that the local vasodilatory capacity was exhausted at rest. The time from tourniquet deflation to pulp peak hyperaemia was the parameter that most clearly separated between the groups [Group A: 21.5 secs (median), group B: 17 secs, group C: 73 secs and group D: greater than 300 secs]. The time from tourniquet deflation to the first increase in flux is probably dependent on hemodynamic factors in the large extremity vessels, and it is possible that this parameter could be used to define levels of hemodynamic significant stenosis in patients with lower limb atherosclerosis. The results also indicate that laser Doppler flowmetry performed during stress testing may be of value in determining appropriate amputation levels.     

Urorectodynamics in patients with colonic inertia

Sixteen female patients with colonic inertia and 12 control women underwent manometric evaluation of their bladder and rectal cavities. After subcutaneous injection of 0.035 mg./Kg. bethanechol, bladder intraluminal pressure increased by over 15 cm. water in 5 patients (31 per cent) and in none of the control group maximal pressure after injection was 11.5 ± 1.6 cm. H₂O ($\text{X}$ ± SE) in patients and 8.5 ± 1 in controls (p < 0.025). The intraluminal rectal pressure reached 23 ± 4 cm. H₂O in patients and only 11.9 ± 1.4 in controls (p < 0.0025). Time taken to reach a peak pressure was faster in patients both in bladder (17.4 ± 0.7 vs. 19.8 ± 1.2 minutes; p < 0.01) and in the rectum (14.6 ± 0.8 vs. 16.3 ± 1.2; p < 0.025). These findings and the clinical presentation suggest an autonomic neuropathic lesion in this group of patients.     

Factors associated with sleep apnea in men with spinal cord injury: a population-based case-control study

OBJECTIVE: To characterize a population of spinal cord injury (SCI) patients with sleep apnea, and to determine associated factors and comorbidities. STUDY DESIGN: Population-based retrospective case-control study. SUBJECTS: 584 male patients served by a Veterans Affairs SCI service. MEASURES: Medical records were reviewed for sleep apnea diagnosis, demographic information, neurologic characteristics, and treatments received. Sleep study reports were not available to determine the nature of abnormal respiratory events (ie central, obstructive, hypoventilation). For each case with tetraplegia, a control tetraplegic subject without sleep apnea diagnosis was selected. RESULTS: We identified 53 subjects with diagnosed sleep apnea: 42 tetraplegic, 11 paraplegic. This represented 14.9% of all tetraplegic and 3.7% of all paraplegic patients in the population (P<0.0001 for comparison of tetraplegic and paraplegic proportions). In tetraplegic subjects, sleep apnea was associated with obesity and more rostral motor level, but not with ASIA Impairment Scale. Medical comorbidities associated with sleep apnea in non-SCI patients, such as hypertension, were more common in case subjects. Less than half of case subjects were receiving some form of treatment. For motor-complete tetraplegics, long-term positive airway pressure treatment was less common with motor level C5 and above compared to C6 and below. CONCLUSION: In this population, sleep apnea has been frequently diagnosed, particularly in tetraplegic subjects. The true prevalence is likely to be considerably higher, since this study considered only previously diagnosed cases. Sleep apnea was associated with obesity and higher neurologic level, but not ASIA Impairment Scale. Medical comorbidities were more frequent in this group, and treatment acceptance was poor with higher level motor-complete injuries. Since the type of sleep apnea (central or obstructive) was not distinguished, we cannot comment on the prevalence and associations based on specific types of sleep apnea.     

Hemodynamic responses to intrapleural insufflation with hemipulmonary collapse

Background: The hemodynamic effects of carbon dioxide (CO2) insufflation with hemipulmonary collapse were studied in consecutive thoracoscopic harvests of the left or right internal mammary artery (IMA), which were used for video-assisted coronary artery bypass grafting. Methods: Thirty-eight patients (30 male, eight female) with a mean age of 69.5 ± 11.5 years were selected, and 33 left and five right IMA were harvested thoracoscopically. After hemipulmonary collapse was established by single-lung ventilation, low-flow (2-3 L/min) CO2 was delivered at a constant intrapleural pressure of 8-10 mmHg. Using electrocardiography, a radial arterial catheter, a Swan-Ganz catheter, and transesophageal echocardiography, we obtained values for seven hemodynamic variables. Baseline data were collected during bilateral lung ventilation. Each variable was then measured during hemipulmonary collapse and insufflation. The significance of any changes was established with Student's t-test after correcting for baseline differences. Results: Insufflation facilitated IMA harvest by expanding the pleural space between the anterior chest wall and heart. Mean insufflation times were 40.8 ± 12.2 min on the left and 33.5 ± 8.5 min on the right. Significant increases from the baseline values were observed in the mean central venous pressure (L:4.7-9.0 mmHg, R: 5.1-14.0 mmHg, p < 0.05), the pulmonary arterial pressure (L: 11.3-17.3 mmHg, R: 12.1-19.9 mmHg, p < 0.05), and the pulmonary capillary wedge pressure (L: 7.2-10.5 mmHg, R: 6.5-10.0 mmHg, p < 0.05). On the right, but not on the left, slight decreases were noted in the mean arterial pressure and cardiac index (71.3-62.6 mmHg, 2.01-1.76 L • min-1 • m-2, p < 0.05). Conclusions: The hemodynamic effect resulting from one-lung collapse plus low-flow CO2 insufflation at 8-10 mmHg for 30-40 min is mild in both hemithoraces, although the impact is greater on the right.     

Differential effect of spinal cord injury and functional impairment on human brain activation

Reorganization of human brain function after spinal cord injury (SCI) has been shown in electrophysiological studies. However, it is less clear how far changes of brain activation in SCI patients are influenced by the extent of SCI (neuronal lesion) or the consequent functional impairment. Positron emission tomography ([15O]-H2O-PET) was performed during an unilateral hand movement in SCI patients and healthy subjects. SCI patients with paraplegia and normal hand function were compared to tetraplegic patients with impaired hand movements. Intergroup comparison between paraplegic patients and healthy subjects showed an increased activation of contralateral sensorimotor cortex (SMC), contralateral thalamus, ipsilateral superior parietal lobe, and bilateral cerebellum. In contrast to this, tetraplegic patients with impaired upper limb function revealed only a significant activation of supplementary motor area (SMA). Correlational analysis in the tetraplegic patients showed that the strength of hand movement was related to the activation of contralateral SMC. However, the severity of upper limb sensorimotor deficit was related to a reduced activation of contralateral SMA and ipsilateral cerebellum. The findings suggest that in paraplegic patients with normal hand function the spinal neuronal lesion itself induces a reorganization of brain activation unrelated to upper limb function. Compared to this, in tetraplegic patients changes of brain activation are related to the impaired upper limb function. Therefore, in patients with SCI a differential impact of spinal lesion and functional impairment on brain activation can be shown. The effect of impaired afferent feedback and/or increased compensatory use of non-impaired limbs in SCI patients needs further evaluation.     

Ultrasonographic assessment of quadriceps and patellar tendon thicknesses in patients with patellofemoral pain syndrome

ObjectiveThe aim of this study was to compare ultrasonographically measured quadriceps and patellar tendon thicknesses between Patellofemoral Pain Syndrome (PFPS) patients and age- and gender-matched healthy controls.MethodsAmong patients who presented to physical therapy and rehabilitation outpatient clinic in January–December 2016, 61 volunteers (28 men and 33 women; mean age: 30.79 ± 6.55 years) who were eligible considering the inclusion and exclusion criteria were enrolled. 30 were diagnosed with PFPS, and the remaining were age- and gender-matched healthy volunteers. Mean age was 30.03 ± 5.67 years in healthy subjects and 45.2% were of male gender. The patient group had mean age of 31.57 ± 7.37 years and 46.7% of the patients were male. Q angles were measured at standing, supine and sitting positions. Patellar and femoral tendon thicknesses and areas were measured ultrasonographically. Kujala questionnaire were used to evaluate the functional status of the participants.ResultsNo significant difference was detected between groups regarding profession, educational background, and body mass indices (BMI) (p > 0.05). Q angle values were significantly higher in the patient group when compared to controls at standing (17.03 ± 3.84 vs. 13.87 ± 1.75°, p < 0.001), supine (16.20 ± 3.74 vs. 13.45 ± 1.79°, p = 0.001) and sitting (16.50 ± 3.28 vs. 13.71 ± 1.72°, p < 0.001) positions. Kujala score was significantly lower in the PFPS group when compared to controls (70.57 ± 8.37 vs. 98.58 ± 2.05, p < 0.001). Patellar (0.39 ± 0.08 vs. 0.32 ± 0.05 cm, p < 0.001) and quadriceps (0.64 ± 0.10 vs. 0.52 ± 0.09 cm, p < 0.001) tendon thicknesses were significantly higher in the PFPS group when compared to controls. There was no significant difference between groups regarding patellar tendon areas (p > 0.05). Patellar tendon thickness values of ≥0.35 cm were found to have 66.7% sensitivity and 67.7% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.771, 95% confidence interval: 0.655–0.887, p < 0.001). Quadriceps tendon thickness values of ≥0.54 cm were found to have 80% sensitivity and 71% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.824, 95% confidence interval: 0.710–0.939, p < 0.001). In PFPS patients, quadriceps tendon thickness had significant positive correlation with age (r = 0.405, p = 0.027) and BMI (r = 0.450, p = 0.013); and significant negative correlation with Kujala score (r = ?0.441, p = 0.015). In the multivariate regression analysis, quadriceps tendon thickness was independently associated with the presence of PFPS (Exp (B): 3.089, 95% confidence interval: 1.344–7.100, p = 0.008).ConclusionOur study demonstrates that ultrasonographically measured patellar and quadriceps tendon thicknesses are significantly higher in subjects with PFPS and particularly, quadriceps tendon thickness may be used for the diagnosis.Level of EvidenceLevel III, Therapeutic Study.     

Toe flexor forces in dancers and non-dancers

Toe flexor force (hallux and second toe) was determined in the right and left feet of 24 dancers and 29 non-dancers (sitting and standing positions) using a commercially-available pressure sensor connected to a voltmeter. For the hallux and second toe combined (all trials combined), average toe flexor force was slightly greater for dancers than non-dancers (dancers, 7 +/- 4 N; non-dancers, 6 +/- 4 N; P<0.049). For dancers and non-dancers combined (all trials), the average toe flexor force of the hallux was more than twice that of the second toe (hallux, 9 +/- 4 N; 2nd toe, 4 +/- 1 N; P<0.0001); average toe flexor force was slightly greater in standing than sitting positions (standing, 7 +/- 4 N; sitting, 6 +/- 3 N; P<0.0001); and the average toe flexor force was slightly greater for the right than left foot (right, 7 +/- 4 N; left, 6 +/- 4 N; P<0.012). The average toe flexor force was greatest for the first repetition and slightly decreased for the second and third repetitions (first repetition, 7 +/- 4 N; second and third repetitions each, 6 +/- 4 N; P<0.0013). Toe flexor force measurement may potentially be applicable to clinical practice as a guide to rehabilitation after injury or as a screening parameter for readiness to advance dance or other athletic training, performance, or competition.     

Assessment of the physiological importance of iliac artery stenosis by laser Doppler flowmetry in pigs.

OBJECTIVE--To test the hypothesis that a curve with two peak values (double hump) recorded by laser Doppler flowmetry over the skin of the lower limb during postocclusive hyperaemia reflects pathological vascular resistance in the aortoiliac segment. DESIGN--Open study. MATERIAL--Six Norwegian Landrace pigs. INTERVENTION--Arterial stenoses were induced in the external iliac arteries. MAIN OUTCOME MEASURES--Presence of double humped laser Doppler curves, relative decrease in laser Doppler flux between the two peaks, and time taken to reach peak hyperaemic flux. RESULTS--Double humped curves were seen only when arterial stenoses were present. The relative decrease in laser Doppler flux between the two peaks, and the time to reach peak hyperaemic flux were related to the blood pressure gradient (mmHg) at the stenosis (r = 0.88 and 0.83, p less than 0.0001). The laser Doppler curve pattern can be explained by similar dynamic changes in arterial blood pressure distal to the tourniquet during hyperaemia. CONCLUSION--These results confirm the hypothesis, and suggest that laser Doppler flowmetry recordings of postocclusive hyperaemia may be a non-invasive way of assessing the condition of the iliac artery.     

Anal pressures in hemorrhoids and anal fissure

Maximal anal pressures have been measured after proctoscopy in 145 patients with hemorrhoids, 48 patients with anal fissure, and 78 asymptomatic control subjects. Anal pressures in patients with hemorrhoids (106 ± 40 cm H₂O) and anal fissure (130 ± 43 cm H₂O) were very significantly higher than those of controls (88 ± 34 cm H₂O) (p < 0.001). Because patients with anal fissure have high anal pressures, these patients should benefit from manual dilatation of the anus or lateral subcutaneous sphincterotomy; however, only young male patients with hemorrhoids have anal pressures that are significantly higher than age- and sex-matched controls. Digital assessment and the two finger test are unreliable indicators of high anal pressure. These results indicate that measurement of anal pressure is useful in assessing the suitability of manual dilatation or sphincterotomy in the treatment of hemorrhoids.     

Contrast echocardiography and transcranial Doppler sonography for detection of a patent foramen ovale

We report the case of a patient, in whom a patent foramen ovale was detected. For the detection of a patent foramen ovale simulation of Valsalva's manoeuvre with a positive airway pressure of 20 cm H2O was applied. Change of ventilation manoeuvre by ventilation with positive airway pressure of 35/30/15 cm H2O at a tidal volume of 1200 ml make a distinct increase in passage of contrast medium from the right to the left atrium. These findings were detected by contrast transesophageal echocardiography and indirectly by transcranial Doppler sonography and were reproducible. This may stress the importance of preoperative screening of patent foramen ovale in patients to be operated on in the sitting position. Contrast echocardiography and the ventilatory manoeuvre with high airway pressure and PEEP might increase the detection rate of patent foramen ovale with a right to left shunt during general anaesthesia.     

Gait analysis in patients operated on for sacrococcygeal teratoma

Background

Long-term follow-up of sacrococcygeal teratoma (SCT) is well established; however, little is known about the effects of extensive surgery in the pelvic and perineal region, which involves disruption of muscles providing maximal support in normal walking.

Methods

Thirteen patients operated on at birth for SCT with extensive muscle dissection underwent gait studies with a Vicon 3-D motion analysis system with 6 cameras. Results were compared with 15 age-matched controls. Statistical analysis was performed with Mann-Whitney test; correlations were sought with Spearman’s correlation coefficient.

Results

All subjects were independent ambulators, and no statistically significant differences were seen in walking velocity and stride length. However, in all patients, toe-off occurred earlier (at 58% ± 1.82% of stride length) than controls (at 65.5% ± 0.52%; P < .05). On kinetics, all patients exhibited, on both limbs, a significant reduction of hip extensory moment (−0.11 ± 0.11 left; −0.16 ± 0.15 right v 1.19 ± 0.08 Newtonmeter/kg; P < .05) and of ankle dorsi/plantar moment (−0.07 ± 0.09 right; −0.08 ± 0.16 v −0.15 ± 0.05 Nm/kg, p < 0.05). Knee power was also significantly reduced (0.44 ± 0.55 right, 0.63 ± 0.45 left v 0.04 ± 0.05 W/kg), whereas ankle power was increased (3 ± 1.5 right; 2.8 ± 0.9 left v 1.97 ± 0.2 W/kg; P < .05). No statistically significant correlation was found between tumor size and either muscle power generation or flexory/extensory moments.

Conclusions

Patients operated on for SCT exhibit nearly normal gait patterns. However, this normal pattern is accompanied by abnormal kinetics of some ambulatory muscles, and the extent of these abnormalities appears to be independent of tumor size. A careful follow-up is warranted to verify if such modifications are stable or progress over the years, thereby impairing ambulatory potential or leading to early arthrosis.     

Cholinergic bronchomotor tone and airway caliber in tetraplegic patients

STUDY DESIGN: Case-control study. OBJECTIVES: To evaluate the resting airway caliber in subjects with tetraplegia; to define the participation of cholinergic innervation in this condition; and to determine if baclofen modifies this pattern. SETTING: A rehabilitation hospital, Brasília, Brazil. METHODS: We studied 18 tetraplegic patients, with complete motor loss between C4 and C8, and 18 healthy control subjects by measuring airway conductance, before and after inhaled ipratropium bromide. RESULTS: At baseline, the pulmonary function parameters revealed mild-to-moderate restrictive impairment in tetraplegic patients as defined by decreases in total lung capacity and predicted percent of slow vital capacity. The average baseline specific airway conductance (sGaw) was less in tetraplegic patients (0.25+/-0.11) than in the control group (0.41+/-0.10 l/s/cm H(2)O) (P<0.0001). All patients had improved post-bronchodilator sGaw >or=40% compared with only four of the 18 controls (P<0.001). The average increase for tetraplegic patients was 235% (+/-93) versus 25% (+/-24) for controls (P<0.0001). Analysis of variance for repeated measurements showed significant difference in sGaw between the control and spinal cord injury (SCI) groups (P<0.0001) following bronchodilator challenge, but found no difference for total gas volume. No difference for mean basal sGaw and bronchodilator challenge was encountered comparing tetraplegic patients using baclofen to those not using it. CONCLUSIONS: Cervical SCI patients have a reduced baseline conductance compared to controls. Marked improvement occurs after an inhaled anticholinergic drug. This behavior was not affected by the use of baclofen. The study adds support to the hypothesis of an increased cholinergic bronchomotor tone in tetraplegic patients.     

Intraaortic balloon pumping improves hemodynamics and right ventricular efficiency in acute ischemic right ventricular failure

Background

Left ventricular unloading has a potentially deleterious effect in right ventricular failure as a result of altered septal interplay. However, a positive effect of an intraaortic balloon pump during right ventricular failure has been suggested. We investigated the impact of intraaortic balloon pumping on hemodynamics and both left and right ventricular function in an experimental model of isolated right ventricular failure.

Methods

Sixteen anesthetized pigs (25 to 34 kg) were used in an in vivo model. Pressure-conductance catheters assessed right and left ventricular pressure-volume relationships. Acute right ventricular failure was induced by right coronary microembolization, and led to severely impaired right ventricular function, reduced cardiac output and arterial pressure, and an increased pulmonary vascular resistance and pulmonary arterial elastance. Animals were then randomized to balloon pump or control groups and evaluated with respect to hemodynamics and ventricular function after 1 hour.

Results

Intraaortic balloon pumping did not alter right or left ventricular contractility. However, balloon pump-treated animals had significantly improved cardiac output (+18% ± 18% versus −6% ± 7%; p = 0.003) and mean arterial pressure (+36% ± 30% versus −7% ± 14%; p = 0.004) compared with controls. Animals in the balloon pump group had lower pulmonary vascular resistance (795 ± 63 versus 912 ± 259 dynes · sec · cm⁻⁵; p < 0.01) and pulmonary arterial elastance (1.14 ± 0.20 versus 1.69 ± 0.65 mm Hg/mL; p < 0.01), and increased stroke volume (22.3 ± 4.7 versus 17.9 ± 4.7 mL; p = 0.016). Right ventricular efficiency was also improved in the balloon pump group (stroke work per pressure-volume area = 0.60 ± 0.14 versus 0.41 ± 0.12; p < 0.01).

Conclusions

Intraaortic balloon pump support does not alter right or left ventricular function in acute right ventricular failure. However, arterial pressure, cardiac output, and right ventricular efficiency are improved, possibly because of a balloon pump-induced reduction in pulmonary arterial resistance.     

A comparison of colour duplex ultrasonography, papaverine testing and common femoral Doppler waveform analysis for assessment of the aortoiliac arteries.

OBJECTIVE: to study the "accuracy" of aortoiliac colour duplex ultrasonography. Design: prospective study. SETTING: vascular laboratory, University Hospital. METHODS: a total of 25 aortoiliac stenoses were studied in 23 patients. For each iliac segment, colour duplex ultrasound, papaverine testing, hyperaemic common femoral Doppler waveform analysis and hyperaemic testing using a thigh pressure cuff were performed. A velocity ratio of two was used to indicate a significant 50% diameter-reducing stenosis, but the velocity differences across stenoses as well as various characteristics of the hyyperaemic common femoral waveform were also studied. Retrospective receiver-operator characteristics and Kappa values were used for analysis. RESULTS: the Kappa agreement between ultrasonography and papaverine testing was 0.12 using peak systolic velocity ratios and 0.8 using hyperaemic peak systolic velocity differences. Hyperaemic common femoral pulsatility (PI) and resistance index (RI) both gained a Kappa level of 0.60. The reactive hyperaemia produced by a thigh cuff was more pronounced than that produced by papaverine. CONCLUSION: although the velocity ratio did not appear to perform well against the papaverine test, its apparent over-sensitivity calls into question the sensitivity of papaverine testing itself. The hyperaemic velocity difference at the stenosis or the hyperaemic PI or RI at common femoral level appear useful, non-invasive indicators of significant aortoiliac arterial disease.     

Contribution of D-Dimer determination in the exclusion of deep venous thrombosis in spinal cord injury patients.

Deep vein thrombosis (DVT) is a common complication of paraplegia despite prophylactic anticoagulant therapy. The diagnosis relies primarily on ultrasonography or phlebography; these investigations are difficult, expensive and can be time-consuming in paraplegic patients. STUDY DESIGN: To evaluate the usefulness of coagulation activation markers in excluding a diagnosis of DVT, D-Dimers, thrombin-antithrombin complexes, prothrombin fragments (F1+2) and activated factor VIIa. OBJECTIVES: To improve the diagnosis of deep venous thrombosis in paraplegic patients. SETTING: This collaborative work was done at Raymond Poincaré Hospital, Garches, France. METHODS: To evaluate the usefulness of coagulation activation markers in excluding a diagnosis of DVT, D-Dimers (D-Di), thrombin-antithrombin (TAT) complexes, prothrombin fragments (F1+2) and activated factor VIIa (FVIIa), were determined in a prospective study of 67 consecutive patients with paraplegia or tetraplegia. Doppler ultrasonography and/or phlebography of the lower limbs and D-Di, TAT, F1+2 level determination were systematically done in each patient at admission to our rehabilitation unit. RESULTS: Despite prophylactic low molecular weight heparin therapy, six of the 67 patients developed DVT diagnosed by radiologic explorations. D-Di levels measured by a reference ELISA (Asserachrom D-Di, Diagnostica Stago) or a new rapid automated turbidimetric test (STA-Liatest D-Di) were greater than 500 ng/ml in all DVT patients and in 40 non-DVT patients, of whom most had urinary tract infections, osteomas, or pressure sores. D-Di values were normal in only 21/67 patients (31%). The negative predictive value of D-Di in our study was 100% since all DVT patients had D-Di values greater than 500 ng/ml. TAT and F1+2 levels were not correlated with D-Di levels but also had a negative predictive value of 100%. Comparison of D-Di levels obtained using the two tests showed that results of the reference ELISA were closely correlated to those of the new rapid automated turbidimetric. TAT, F1+2, and factor VIIa are not useful for measuring hypercoagulability in paraplegic or tetraplegic patients since no rapid tests for determining these parameters are available. CONCLUSION: D-Di levels determined using an ELISA or a new rapid automated turbidimetric test have a good negative predictive value for DVT in paraplegic or tetraplegic patients and may reduce the need for Doppler ultrasonography and/or phlebography by 31%.