A comparative study into the effects of venous and arterial blood on clot microstructure in critically unwell patients. Assessment of the diagnostic potential of a biomarker of haemostasis

Blood for coagulation analysis can be sampled from the arterial or venous system in intensive care units (ICU). The determination of clot microstructure and strength by fractal analysis (df) gives valuable information in a range of vascular haemostatic disease and sepsis. We aimed to determine if df could be measured equally and comparatively in arterial or venous blood, and 45 critically ill patients in an ICU were recruited. df was found to be readily measured in arterial blood with results comparable to those in venous blood and that add value of df as a potential marker of haemostasis in these patients.

The Impact of Patient Characteristics and Antiplatelet Regimes on Clot Microstructure in Patients Treated for ST Elevation Myocardial Infarction: Clot Microstructure can Evaluate Therapeutic Efficacy

BACKGROUND

Unfavourable clot microstructure is associated with adverse outcomes in ST elevation myocardial infarction (STEMI). We investigated the effect of comorbidities and anti-platelet treatment on clot microstructure in STEMI patients using fractal dimension (d_f), a novel biomarker of clot microstructure derived from the visco-elastic properties of whole blood.

METHODS

Patients with STEMI (n = 187) were recruited sequentially receiving aspirin with Clopidogrel (n = 157) then Ticagrelor (n = 30). Patient characteristics and blood for rheological analysis obtained. We quantified d_f using sequential frequency sweep tests to obtain the phase angle of the Gel Point which is synonymous with the clot microstructure.

RESULTS

Higher d_f was observed in males (1.755 ± 0.068) versus females (1.719 ± 0.061, p = .001), in patients with diabetes (1.786 ± 0.067 vs 1.743 ± 0.046, p < .001), hypertension (1.760 ± 0.065 vs 1.738 ± 0.069, p = .03) and previous MI (1.787 ± 0.073 vs 1.744 ± 0.066, p = .011) compared to without. Patients receiving Ticagrelor had lower d_f than those receiving Clopidogrel (1.708 ± 0.060 vs 1.755 ± 0.067, p < .001). Significant correlation with d_f was found with haematocrit (r = 0.331, p < .0001), low-density lipoprotein (LDL) (r = 0.155, p = .046) and fibrinogen (r = 0.182, p = .014). Following multiple regression analysis, diabetes, LDL, fibrinogen and haematocrit remained associated with higher d_f while treatment with Ticagrelor remained associated with lower d_f.

CONCLUSIONS

The biomarker d_f uniquely evaluates the effect of interactions between treatment and underlying disease on clot microstructure. STEMI patients with diabetes and elevated LDL had higher d_f, indicating denser clot. Ticagrelor resulted in a lower d_f than Clopidogrel signifying a less compact clot.

The effects of apixaban on clot characteristics in atrial fibrillation: A novel pharmacodynamic biomarker

Atrial fibrillation (AF) is a major risk factor for stroke. We aim to characterize AF patients and the effects of apixaban therapy in terms of clot microstructure using gel point analysis, a novel biomarker. Seventy-eight patients were included in the study, 50 Stroke with AF (AF-S), and 28 AF without stroke (AF). Pre- and post-anticoagulation samples were collected: gel point (GP) analysis was performed to obtain (i) TGP (the time taken to reach the GP or the clot formation time) and (ii) d_{f ,} the fractal dimension of the clot, a quantification of clot fibrin microstructure at the GP. At baseline, the AF-S group had a d_f  = 1.70 (±0.05) and TGP = 306 (±73 s). The AF group had a df = 1.70 ± 0.05 and TGP = 346 ± 78 s, showing a significantly shortened TGP in the stroke group (p = .008). For both groups, apixaban significantly prolonged TGP, p = .005, but resulted in no change in df. Apixaban prolonged clotting time while having no significant impact on the blood's ability to form stable clots (no change in d_f ). This indicates that apixaban provides protection from the formation of thrombi by reducing clotting kinetics.

The effect of the acute inflammatory response of burns and its treatment on clot characteristics and quality: A prospective case controlled study

INTRODUCTION

Burns are known to have an effect on coagulation in the early period after burn. Current coagulation tests have been criticised in acute burns due to their inherent limitations. This study aims to investigate the potential for a new quantitative functional biomarker of clot quality, fractal dimension, to identify changes in clot microstructure as a result of the burn inflammatory response and its treatment.

METHODS

A total of fifty-eight burn patients were included in this prospective case-controlled study. The control group (29 patients mean TBSA 1%), and case group (29 patients mean TBSA 30%) were compared at baseline and the case group investigated further over four time points (baseline, 12h, 24h and 5-7 days). Fractal analysis was performed, as well as current markers of coagulation, inflammatory markers and point-of-care tests, Thromboelastography and Multiplate analysis.

RESULTS

Fractal dimension did not differ between groups at admission (1.73±0.06 and 1.72±0.1), and fell within the healthy index normal range (1.74±0.7), suggesting a normal clot microstructure in the early period after burn. Fractal dimension significantly reduced from baseline over the first 24h following injury (1.59±0.03 p<0.005), indicating a significant reduction in mechanical clot strength and functionality consistent with a hypocoagulable state, not identified with other markers.

CONCLUSIONS

This is the first study to quantify the changes in clot microstructure following burn injury. This study confirms clot microstructure is significantly altered during the first 24h after burn, with the production of a weaker, more porous fibrin clot, consistent with a hypocoagulable state.

In vitro clot model to evaluate fibrin-thrombin effects on fractal dimension of incipient blood clot

INTRODUCTION

This aim of this study is to investigate the individual effects of varying concentrations of thrombin and fibrinogen on clot microstructure (characterised through the fractal dimension of the incipient clot network, df) and clot formation time (TGP) using a fibrin-thrombin clot model. df and TGP markers are measured using a haemorheological method that has already been investigated for whole blood.

METHODS

This is an in vitro study using three thrombin concentrations (0.1, 0.05 and 0.02 NIH/ml) and two fibrinogen concentrations (8 mg/ml and 12 mg/ml) to investigate a fibrin-thrombin clot model. The haemorheological changes were measured at the gel point using df and TGP.

RESULTS

Fractal dimension (df) increased with increasing concentrations of thrombin both at 8 mg/ml (1.60±0.024, 1.67±0.022, 1.74±0.079) and 12 mg/ml fibrinogen concentrations (1.63±0.02, 1.87±0.019, 1.95±0.014). On the other hand, TGP decreased for both 8 mg/ml (1089±265, 637±80, 223±22 seconds) and 12 mg/ml fibrinogen concentrations (2008±247, 776±20, 410±20 seconds). In contrast to previous studies investigating whole blood, TGP increased with higher fibrinogen levels.

CONCLUSIONS

The findings from this fibrin-thrombin clot model confirmed that df and TGP can detect changes in the incipient clot following manipulation of fibrinogen and thrombin concentration. df increases (indicating stronger clot) with higher concentrations of thrombin and fibrinogen. On the other hand, TGP decreased as expected with higher thrombin level but not with higher fibrinogen concentrations.

Linear rheology as a potential monitoring tool for sputum in patients with Chronic Obstructive Pulmonary Disease (COPD)

BACKGROUND

The rheological properties of sputum may influence lung function and become modified in disease.

OBJECTIVE

This study aimed to correlate the viscoelastic properties of sputum with clinical data on the severity of disease in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Sputum samples from COPD patients were investigated using rheology, simple mathematical modelling and Scanning Electron Microscopy (SEM). The samples were all collected from patients within two days of their admission to Prince Philip Hospital due to an exacerbation of their COPD. Oscillatory and creep rheological techniques were used to measure changes in viscoelastic properties at different frequencies over time.

RESULTS

COPD sputum was observed to behave as a viscoelastic solid at all frequencies studied. Comparing the rheology of exacerbated COPD sputum with healthy sputum (not diagnosed with a respiratory disease) revealed significant differences in response to oscillatory shear and creep-recovery experiments, which highlights the potential clinical benefits of better understanding sputum viscoelasticity. A common power law model G(t)=G0(tτ0)-m was successfully fitted to experimental rheology data over the range of frequencies studied.

CONCLUSIONS

A comparison between clinical data and the power law index m obtained from rheology, suggested that an important possible future application of this parameter is as a potential biomarker for COPD severity.

The 'clicky hip': to refer or not to refer?

Aims

The significance of the 'clicky hip' in neonatal and infant examination remains controversial with recent conflicting papers reigniting the debate. We aimed to quantify rates of developmental dysplasia of the hip (DDH) in babies referred with 'clicky hips' to our dedicated DDH clinic.

Patients and Methods

A three-year prospective cohort study was undertaken between 2014 and 2016 assessing the diagnosis and treatment outcomes of all children referred specifically with 'clicky hips' as the primary reason for referral to our dedicated DDH clinic. Depending on their age, they were all imaged with either ultrasound scan or radiographs.

Results

There were 69 'clicky hip' referrals over the three-year period. This represented 26.9% of the total 257 referrals received in that time. The mean age at presentation was 13.6 weeks (1 to 84). A total of 19 children (28%) referred as 'clicky hips' were noted to have hip abnormalities on ultrasound scan, including 15 with Graf Type II hips (7 bilateral), one Graf Type III hip, and three Graf Type IV hips. Of these, ten children were treated with a Pavlik harness, with two requiring subsequent closed reduction in theatre; one child was treated primarily with a closed reduction and adductor tenotomy. In total, 11 (15.9%) of the 69 'clicky hip' referrals required intervention with either harness or surgery.

Conclusion

Our study provides further evidence that the 'clicky hip' referral can represent an underlying diagnosis of DDH and should, in our opinion, always lead to further clinical and radiological assessment. In the absence of universal ultrasound screening, we would encourage individual units to carefully assess their own outcomes and protocols for 'clicky hip' referrals and tailor ongoing service provision to local populations and local referral practices. Cite this article: Bone Joint J 2018;100-B:1249-52.

Control of collagen gel mechanical properties through manipulation of gelation conditions near the sol-gel transition

The ability to control the mechanical properties of cell culture environments is known to influence cell morphology, motility, invasion and differentiation. The present work shows that it is possible to control the mechanical properties of collagen gels by manipulating gelation conditions near the sol gel transition. This manipulation is accomplished by performing gelation in two stages at different temperatures. The mechanical properties of the gel are found to be strongly dependent on the duration and temperature of the first stage. In the second stage the system is quickly depleted of free collagen which self assembles into a highly branched network characteristic of gelation at the higher temperature (37 °C). An important aspect of the present work is the use of advanced rheometric techniques to assess the transition point between viscoelastic liquid and viscoelastic solid behaviour which occurs upon establishment of a sample spanning network at the gel point. The gel time at the stage I temperature is found to indicate the minimum time that the gelling collagen sample must spend under stage I conditions before the two stage gelation procedure generates an enhancement of mechanical properties. Further, the Fractional Maxwell Model is found to provide an excellent description of the time-dependent mechanical properties of the mature collagen gels.

Effects of unidirectional flow shear stresses on the formation, fractal microstructure and rigidity of incipient whole blood clots and fibrin gels

Incipient clot formation in whole blood and fibrin gels was studied by the rheometric techniques of controlled stress parallel superposition (CSPS) and small amplitude oscillatory shear (SAOS). The effects of unidirectional shear stress on incipient clot microstructure, formation kinetics and elasticity are reported in terms of the fractal dimension (d_f) of the fibrin network, the gel network formation time (T_GP) and the shear elastic modulus, respectively. The results of this first haemorheological application of CSPS reveal the marked sensitivity of incipient clot microstructure to physiologically relevant levels of shear stress, these being an order of magnitude lower than have previously been studied by SAOS. CSPS tests revealed that exposure of forming clots to increasing levels of shear stress produces a corresponding elevation in d_f, consistent with the formation of tighter, more compact clot microstructures under unidirectional flow. A corresponding increase in shear elasticity was recorded. The scaling relationship established between shear elasticity and d_f for fibrin clots and whole blood confirms the fibrin network as the dominant microstructural component of the incipient clot in terms of its response to imposed stress. Supplementary studies of fibrin clot formation by rheometry and microscopy revealed the substantial additional network mass required to increase d_f and provide evidence to support the hypothesis that microstructural changes in blood clotted under unidirectional shear may be attributed to flow enhanced thrombin generation and activation. CSPS also identified a threshold value of unidirectional shear stress above which no incipient clot formation could be detected. CSPS was shown to be a valuable haemorheological tool for the study of the effects of physiological and pathological levels of shear on clot properties.

A new biomarker quantifies differences in clot microstructure in patients with venous thromboembolism

This study compared patients with venous thromboembolism (VTE) to non-VTE patients using a biomarker of clot microstructure (df ) and clot formation time (TGP ). df was the only marker that identified a significant difference (P < 0·001) between the VTE (n = 60) and non-VTE cohorts (n = 69). The 'abnormal' clot microstructures in the VTE patients suggests either inadequate response to anticoagulant therapy or the presence of a procoagulant state not detected by other markers of coagulation (i.e., International Normalized Ratio). Furthermore, elevated values of df in first time VTE patients who later develop a secondary event indicates that df may identify those at risk of recurrence.

Studies of whole blood coagulation by oscillatory shear, thromboelastography and free oscillation rheometry

We report studies of the coagulation of samples of whole human blood by oscillatory shear techniques, including Fourier Transform Mechanical Spectroscopy (FTMS). These techniques are used herein to identify the Gel Point of coagulating blood in terms of the Chambon-Winter Gel Point criterion which provides a rheometrical basis for detecting the establishment of an incipient clot. A comparison of the results of FTMS with those obtained from measurements involving a Thromboelastograph (TEG) and a Free Oscillation Rheometer (FOR) indicate that the latter techniques are not capable of detecting the incipient clot, whose establishment occurs several minutes prior to TEG or FOR-based assessments of clot formation time. The results of the present study suggest that FTMS is a useful tool in blood clotting research, being capable of providing a global coagulation profile in addition to detecting the instant of incipient clot formation.

Rheometry and associated techniques for blood coagulation studies

This review considers various rheometrical approaches that have been adopted to study blood coagulation, with special reference to the rheological assessment of clotting time and studies of the evolution of viscoelasticity during the course of fibrin polymerization and cross-linking. The significance of the Gel Point in blood coagulation studies is discussed as a common feature of many of these studies in that they attempt to detect a liquid-to-solid transition during coagulation. Coagulation studies based on various forms of complex shear modulus measurements are considered, the latter being based principally on controlled stress and controlled strain rheometers. Also considered are the long established technique of thromboelastography and several emerging techniques such as wave propagation measurements, free oscillation rheometry, quartz crystal microbalance measurements and surface plasmon resonance.

Comment on "The Brain of LB1, Homo floresiensis"

Endocast analysis of the brain Homo floresiensis by Falk et al. (Reports, 8 April 2005, p. 242) implies that the hominid is an insular dwarf derived from H. erectus, but its tiny cranial capacity cannot result from normal dwarfing. Consideration of more appropriate microcephalic syndromes and specimens supports the hypothesis of modern human microcephaly.

Rheometrical and computational studies of blood viscoelasticity during coagulation

The rheological behaviour of coagulating human blood has been measured using multiple strain wave frequencies. The results indicate that coagulating blood, prior to the point of incipient clot formation, can be modelled by a modified form of the Gross-Marvin 'ladder' model, and the benefits of such modeling for blood coagulation are discussed.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Indirect institutional revenue generated from an academic primary care clinical network

BACKGROUND AND OBJECTIVES

As the financial performances of US academic health centers have faltered under managed care and the Balanced Budget Act of 1997, increasing attention has been paid to the costs and benefits of operating primary care networks. This study examines the indirect revenues to a university hospital and faculty group practice that result from such a primary care network using a method of abstracting billing data.

METHODS

A primary care patient cohort was identified by selecting all patients who generated at least one charge in any of the 10 primary care clinics in the network over a 15-month period. All charges from the hospital and the faculty practice group for this cohort were then examined during a 6-month period, and the total charges generated in the primary care setting were compared with charges generated elsewhere in the health system.

RESULTS

The primary care patient cohort included 56,459 patients and generated a total of $7,243,312 in charges for primary care services, $43,559,741 of charges in the hospital billing system for non-primary care services, and $8,825,611 of charges for services from specialty faculty. This cohort accounted for 18.5% of the gross charges for hospital care and 17.6% of charges generated by the specialty physicians.

CONCLUSIONS

Using a simple and replicable methodology, this study estimates a substantial financial benefit to the hospital and specialty practices from a primary care network.

Bisphosphonates and nephrocalcinosis in a rabbit leg lengthening model: a histological and therapeutic comparison

We performed a comparison of the effects of two bisphosphonates, pamidronate and zoledronic acid, on regenerate bone mineral content in distraction osteogenesis in an immature rabbit model. Single dose zoledronic acid was found to be 18 times more potent at producing an increase in bone mineral content than pamidronate per mg/kg of drug infused at surgery. Histological examination of all rabbit kidneys was performed at trial completion. Nephrocalcinosis was identified in 14 of 20 kidneys of rabbits infused with pamidronate, but was not detected in the 20 kidneys of those rabbits infused with zoledronic acid. A further 20 kidneys from rabbits given a second dose of zoledronic acid were also found to be free of signs of nephrocalcinosis. Three of 40 control kidneys exhibited signs of nephrocalcinosis. The increased potency of zoledronic acid allowed us to give one-tenth the dose of pamidronate, with increased therapeutic efficacy and no evidence of nephrocalcinosis.

Perceived risks of conventional and organic produce: pesticides, pathogens, and natural toxins

Public risk perceptions and demand for safer food are important factors shaping agricultural production practices in the United States. Despite documented food safety concerns, little attempt has been made to elicit consumers' subjective risk judgments for a range of food safety hazards or to identify factors most predictive of perceived food safety risks. In this study, over 700 conventional and organic fresh produce buyers in the Boston area were surveyed for their perceived food safety risks. Survey results showed that consumers perceived relatively high risks associated with the consumption and production of conventionally grown produce compared with other public health hazards. For example, conventional and organic food buyers estimated the median annual fatality rate due to pesticide residues on conventionally grown food to be about 50 per million and 200 per million, respectively, which is similar in magnitude to the annual mortality risk from motor vehicle accidents in the United States. Over 90% of survey respondents also perceived a reduction in pesticide residue risk associated with substituting organically grown produce for conventionally grown produce, and nearly 50% perceived a risk reduction due to natural toxins and microbial pathogens. Multiple regression analyses indicate that only a few factors are consistently predictive of higher risk perceptions, including feelings of distrust toward regulatory agencies and the safety of the food supply. A variety of factors were found to be significant predictors of specific categories of food hazards, suggesting that consumers may view food safety risks as dissimilar from one another. Based on study findings, it is recommended that future agricultural policies and risk communication efforts utilize a comparative risk approach that targets a range of food safety hazards.

A 'safe' surgical technique for stabilisation of the sternoclavicular joint: a cadaveric and clinical study

In symptomatic patients with recurrent anterior sternoclavicular dislocation, surgery may be required to stabilise the joint. Posterior sternoclavicular dislocations may also require open reduction and stabilisation due to the complications that may arise. We present a new, 'safe' technique of surgical stabilisation of the sternoclavicular joint that is not technically demanding and does not require exposure of the first rib, as is often the case in other methods described. The repair was tested in cadavers before being employed in three patients and was found to be effective under both static and dynamic loading. The early clinical results prove encouraging.

A comparison of organic and conventional fresh produce buyers in the Boston area

Food safety concerns and the demand for organically grown produce have increased significantly in the United States over the last decade. Key differences in lifestyle characteristics, food safety attitudes and beliefs, perceived food safety risks, and valuation of health risk reductions between organic and conventional food buyers remain largely unknown, however. To better characterize how buyers of organic fresh produce differ from their conventional counterparts, over 700 food shoppers were sampled from ten major retail stores in the Boston area. Survey results show that self-reported organic buyers are more likely than conventional buyers to engage in a variety of health-promoting and environmentally friendly behaviors. Organic buyers are less trusting of federal food safety agencies than are conventional buyers, and perceive greater benefits associated with organically grown produce than do their conventional counterparts. Further, organic buyers have significantly higher risk perceptions than do conventional buyers for food safety hazards associated with conventionally grown produce. Compared to conventional buyers, organic produce buyers also perceive significant risk reductions associated with switching to organically grown produce and are willing to pay a higher price to reduce perceived food safety risks. Few sociodemographic differences between buyer types were observed, possibly due to how organic and conventional food stores were matched. Survey findings highlight the need for greater public education about a range of food safety issues and farming practices to ensure that consumers are making informed decisions in the marketplace.

Osteitis pubis and instability of the pubic symphysis. When nonoperative measures fail

Seven rugby players with osteitis pubis and vertical instability at the pubic symphysis were treated operatively after nonoperative treatment had failed to improve their symptoms. The vertical instability was diagnosed based on flamingo view radiographs showing greater than 2 mm of vertical displacement. The players had undergone at least 13 months of nonoperative therapy before surgery was considered. Operative treatment consisted of arthrodesis of the pubic symphysis by bone grafting supplemented by a compression plate. At a mean follow-up of 52.4 months, all patients were free of symptoms and flamingo views confirmed successful arthrodesis with no residual instability of the pubic symphysis. Based on our results with this procedure, we believe that arthrodesis of the pubic symphysis has a role in the treatment of osteitis pubis that is recalcitrant to nonoperative treatment. The combination of osteitis pubis and vertical pubis symphyseal instability may be the cause of failure of nonoperative treatment.

Avascular necrosis and the Aberdeen splint in developmental dysplasia of the hip

Between January 1987 and December 1988 there were 7575 births in the Swansea maternity unit. Of these 823 (10.9%) were considered to be at 'high risk' for developmental dysplasia of the hip (DDH). Static ultrasound examination was performed in each case and the results classified on the basis of the method of Graf. A total of 117 type III-IV hips in 83 infants was splinted using the Aberdeen splint. Radiographs of these hips were taken at six and 12 months. Hilgenreiner's measurements of the acetabular angle were made in all cases and the development of the femoral capital epiphysis was assessed by measuring the epiphyseal area. The effect of splintage on the acetabular angle and the epiphyseal area between the normal and abnormal splinted hips was compared. Radiographs of 16 normal infants (32 normal unsplinted hips) were used as a control group. This cohort has now been followed up for a minimum of nine years. There have been no complications as a result of splintage. The failure rate was 1.7% or 0.25 per 1000 live births. No statistical difference was found when comparing the effect of splintage on the acetabular angle and epiphyseal area between normal and abnormal splinted hips and normal unsplinted hips. Our study has shown that while the Aberdeen splint had a definite but small failure rate, it was safe in that it did not produce avascular necrosis. The current conventional view that a low rate of splintage is always best is therefore brought into question if the Aberdeen splint is chosen for the management of neonatal DDH.

Use of an elastic intramedullary nail in difficult humeral fractures

Debate continues over implant selection when surgical intervention is deemed necessary in the management of diaphyseal fractures of the humerus. We present a series of patients in which we used an elastic intramedullary nail to manage a variety of difficult humeral fractures and discuss the theoretical advantages which we feel this method offers.

Cavitation phenomena in water involving the reflection of ultrasound pulses from a free surface, or from flexible membranes

We report findings from studies of water subjected to tension by pulsed dynamic stressing which may have significance in the context of assessing the safety of biomedical applications of low-frequency ultrasound. When incident on bubbles near a free surface (or a flexible membrane), shockwaves generated by cavitation bubble collapse are found to lead to the production of liquid jets which are directed towards the surface. Tension pulses generated by reflection of these shockwaves at a free surface initiate, and propagate, the growth of further cavitation bubbles. Estimates of the tensile strength of water, Fc, from measurements of the velocity of these pulses suggest that Fc is far higher than has previously been reported for experiments involving the reflection of low-frequency ultrasound; and the estimate of Fc reported here considerably exceeds the values of tension thought to be generated by ultrasound in many biomedical applications.

Compartment pressure monitoring--current UK orthopaedic practice

Debate continues over the use of compartment pressure monitoring devices in the diagnosis of compartment syndrome. We present the results of a survey that was designed to explore this issue. The majority of UK trauma and orthopaedic surgeons surveyed advocate making the diagnosis of compartment syndrome by a combination of clinical acumen and compartment pressure measurements. Less than half of the trauma centres surveyed had pressure monitoring equipment available. There is marked variation in opinion regarding the threshold level for surgery when monitoring is applied.

Reflex inhibition of the quadriceps femoris muscle after injury or reconstruction of the anterior cruciate ligament

A burst-superimposition technique was used to assess the strength of the quadriceps femoris muscle in three groups of patients. Group 1 comprised twenty patients who had had a torn anterior cruciate ligament of the knee and had a reconstruction of the ligament one to six months after the injury. Group 2 comprised twelve patients who had had a torn anterior cruciate ligament for an average of three months (a subacute tear). Group 3 comprised eight patients who had had a torn anterior cruciate ligament for an average of two years (a chronic tear). The patients in Groups 2 and 3 had not had an operation for the torn ligament. The patients in Groups 1 and 3 had no evidence of failure of activation of the involved quadriceps, but nine of the twelve patients in Group 2 had reflex inhibition of contraction of the muscle.

Fatigability of human quadriceps femoris muscle following anterior cruciate ligament reconstruction

The responses of quadriceps femoris muscles to an electrically elicited fatigue test were recorded from both lower extremities of 18 patients who had recently undergone unilateral, anterior cruciate ligament reconstruction. The fatigue test consisted of 40 pps, 13-pulse electrical trains that were repeated once per second for 3 min. The intensity of stimulation was set for each extremity to produce 20% of the maximum voluntary isometric contraction of the uninvolved muscle. The uninvolved quadriceps femoris muscle showed a significantly greater rate of decline in force over the first minute than the involved muscle (0.803%.s-1 for uninvolved muscle vs 0.620%.s-1 for involved muscle). Similarly, the average forces produced over the last minute were significantly lower for the uninvolved than the involved quadriceps femoris muscle (uninvolved = 42.6%, involved = 50.4% of their original forces). These surprising results showed that the involved quadriceps femoris muscles were more endurant than the uninvolved muscles. It is suggested that the increases in endurance of the involved muscle may have been due, in part, to greater recruitment of Type I fibers with electrical stimulation or selective Type II fiber atrophy in the involved muscle.

Concurrent administration of albumin with total parenteral nutrition in sick newborn infants

The effects of concurrent administration of albumin with total parenteral nutrition were studied in 12 premature newborns (birth weight 1.26 +/- 0.1 kg [mean +/- SEM] and gestational age 30 +/- 0.8 weeks [mean +/- SEM]) compared with a control group of 12 premature newborns (birth weight 1.17 +/- 0.2 kg and gestational age 29 +/- 0.1 weeks) who received total parenteral nutrition. All newborns had a plasma albumin level below 3 g/dL and were in cardiorespiratory distress requiring assisted ventilation. Albumin supplementation of total parenteral nutrition resulted in a sustained increase in serum albumin concentration as well as increased mean arterial blood pressures in the study group. Slow albumin infusion had no observed effect on the severity of respiratory distress. Study group infants regained birth weight earlier than control group infants. These data suggest that the concurrent administration of albumin may be clinically beneficial in critically ill newborn infants.

Intracavity drainage for bullous, emphysematous lung disease: experience with the Brompton technique

Twenty two operations have been performed on 20 patients for the relief of symptoms due to bullous lung disease. Open intubation drainage of the bullae was used in all patients, the technique initially devised by Monaldi for the treatment of intrapulmonary tuberculous abscesses having been modified. Three patients died after surgery. Mortality was associated with low preoperative FEV1 (median 350 ml) and higher preoperative arterial carbon dioxide tension (PaCO2) (median 7.8 kPa). Symptomatic improvement was reported by 16 of the remaining 17 patients and was maintained over a median follow up period of 1.6 years. This was accompanied by objective improvement in lung function with a 22% median improvement in FEV1, an 11% median reduction in total lung capacity, and a 26% median reduction in residual volume. In one patient symptoms were unchanged after surgery. The technique described provides a simple method for decompressing bullae by means of a minimally invasive surgical procedure. It also allows for the treatment of further bullae at a later date by closed intubation under local anaesthetic. It has proved a suitable approach for all but those with the poorest lung function and is now our treatment of choice.

Fetal surgery: the social implications of medical and surgical treatment of the unborn child

Advances in microsurgery provide physicians with the opportunity to correct malformations of the fetus prior to birth. However, these techniques are being developed at a time when the legal status of the unborn is unclear and the rights of pregnant women to determine the nature of their care are not universally recognized. This paper examines some of the social implications of medical and surgical treatment of the fetus. In attempting to clarify the rights of pregnant women in relationship to the rights of the fetus, the authors examine the law related to abortion and the protection of the fetus after it has achieved viability. Ambiguities in the legal interpretations of viability, coupled with societal ambivalence over the rights of women have resulted in confusion. Several cases have been reported in which the courts overrode an otherwise competent woman's refusal of surgery in the interest of the unborn fetus. Thus, legal precedent exists for the judicial suspension of the rights of pregnant women to consent or refuse medical or surgical treatment. This trend in the law may reflect more conservative values regarding the rights of women. At the same time, the benefits to the fetus remains unexamined outside of a medical frame of reference.

Improving the care of asthmatic patients in general practice

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