Patient Obesity Influences Pelvic Lift During Cup Insertion in Total Hip Arthroplasty Through a Lateral Transgluteal Approach in Supine Position

Background

Movement of the pelvis during implantation of total hip arthroplasty (THA) has a major influence on the positioning of the acetabular cup. Strong traction caused by retractors leads to iatrogenic pelvic lift and can thus be partly responsible for cup malpositioning. The objective of this study was to investigate such factors that influence pelvic lift.

Impact of impaired inspiratory muscle strength on dyspnea and walking capacity in sarcoidosis

BACKGROUND: Dyspnea and fatigue are frequent but poorly understood symptoms in sarcoidosis patients. This study was aimed at assessing the clinical impact of inspiratory muscle impairment on dyspnea and exercise tolerance. This is the first study using nonvolitional tests that are independent of the patient's cooperation and motivation in addition to volitional tests of inspiratory muscle strength in patients with sarcoidosis. METHODS: Peak maximal inspiratory mouth pressure (Pimaxpeak), maximal inspiratory pressure sustained for 1.0 s (Pimax1.0), twitch mouth pressure (TwPmo), lung function test results, blood gas measurements, 6-min walking distance (6MWD), and Borg dyspnea scale (BDS) scores were assessed in 24 male sarcoidosis patients and 24 healthy male control subjects matched for age and body mass index. RESULTS: Mean (+/- SD) Pimaxpeak (95.2 +/- 25.3% vs 124.6 +/- 23.4% predicted, respectively; p < 0.001) and Pimax1.0 (85.6 +/- 31.4% vs 125.8 +/- 26.8% predicted, respectively; p < 0.001) were lower in sarcoidosis patients compared to control subjects. TwPmo tended to be lower in sarcoidosis patients, and there were three patients who had TwPmo values of < 1.0 kPa, which is a strong indicator of inspiratory muscle weakness. The mean 6MWD was 582 +/- 97 m in sarcoidosis patients and 638 +/- 65 in control subjects (p = 0.025). The mean BDS score was higher in sarcoidosis patients (3.3 +/- 1.7 vs 0.2 +/- 0.5, respectively; p < 0.001). Compared to maximal inspiratory pressure, lung function parameters, and blood gas levels, TwPmo was the strongest predictor for 6MWD (r = 0.663; p = 0.003) and BDS score (r = 0.575; p = 0.012) in sarcoidosis patients following multiple linear regression analysis. CONCLUSIONS: Impairment of inspiratory muscle strength occurs in sarcoidosis patients, and has been suggested to be an important factor causing dyspnea and reduced walking capacity, but this is only reliably detectable when using nonvolitional tests of inspiratory muscle strength.     

Flow-dependent resistance of nasal masks used for non-invasive positive pressure ventilation

OBJECTIVE AND BACKGROUND: Endotracheal tube resistance is known to be flow-dependent and this understanding has improved the application of invasive ventilation. However, similar physiological studies on the interface between patients and non-invasive positive pressure ventilation (NPPV) have not been performed. Therefore, this study was aimed at investigating the resistance of nasal masks used for NPPV. METHODOLOGY: The flow-dependent pressure drop of the small (S), medium-small (MS) and medium (M) Contour Nasal Mask (Respironics Inc., Murrysville, PA, USA) was measured with and without a connecting tube (length 18 cm, internal diameter 1.5 cm) in a laboratory study. The resistance was calculated by Rohrer's equation using the standard least-squares-fit technique. The present study explicitly differentiated between the resistance of the nasal mask alone when measured against atmosphere and the additional resistance caused by the nasal mask when airtightly fitted to a model head (interaction with the face). RESULTS: Higher flow rates resulted in a non-linearly increasing pressure drop across the interface. This flow-dependent resistance of the S/MS/M mask was comparably low when not interacting with the face, but increased when interacting with the face. This flow-dependent resistance of the mask was several-fold higher when adding the connection tube and tended to be higher during expiration. CONCLUSION: There is a non-linear flow-dependent pressure drop across the nasal mask which is low and independent of its size, but increases when interacting with the face. The connecting tube is the major determinant of the resistance originating from facial appliances used for NPPV.     

High-Flow-Sauerstoff in der Therapie der akuten respiratorischen Insuffizienz

High-flow oxygen via nasal cannulas represents a new noninvasive treatment option for patients with hypoxemic respiratory failure. Here, a warmed and humidified air–oxygen mixture is delivered at a high-flow rate of 20–60 l/min and with a defined fraction of inspired oxygen (F_iO₂)_. High-flow oxygen is a further treatment option that is increasingly used next to conventional oxygen support and noninvasive positive pressure ventilation in the intensive care unit and is in focus of current research. Studies comparing high-flow oxygen and both conventional oxygen support and noninvasive positive-pressure ventilation in hypoxemic respiratory failure have suggested comparable treatment success and outcome. Furthermore, high-flow oxygen is reportedly better tolerated by patients with fewer side effects compared to conventional oxygen support and noninvasive positive-pressure ventilation.     

Isoproterenol, norepinephrine and phosphodiesterase inhibitors are blockers of the depressed fast Na+-system in ventricular muscle fibers

It is generally agreed that β-adrenergic transmitters do not influence the maximum rate of rise of action potentials of cardiac fibers with an intact fast Na⁺-system. Inhibitory effects of epinephrine have only been reported for a Mg-activated fast current [9]. Fibers with a depressed fast Na⁺-system have been studied under various experimental conditions, some of them mimicking infarct-like environments [1,5]. In some respects the depressed fast sodium-system reacts differently, e.g. recovery from inactivation [3], Ca²⁺-effects [10], TTX-influences [6] and susceptibility to antiarrhythmic drug influence [4].We have studied the influence of isoproterenol, norepinephrine and of phosphodiesterase inhibitors on the depressed fast Na⁺-system in guinea-pig papillary muscles and gained results which are completely different to those in fibers with intact fast Na⁺-system.     

Blood supply to the maxillary sinus relevant to sinus floor elevation procedures

The maxillary blood supply is essential for preserving the vitality of the affected maxillary region, integration of the grafting material, and wound healing such as following sinus floor elevation. Although it is well established that edentulous maxillae demonstrate a decreasing vascularity as bone resorption progresses, the vascular conditions relevant to sinus floor elevation procedures have not been investigated yet. This study deals with maxillary arteries relevant to sinus floor elevation surgery and examines the vascularization of the lateral maxilla after tooth loss. The vessels of the lateral maxilla of 18 maxillary specimens (10 male, 8 female, mean age 67 years) were prepared anatomically and the local main arteries, the number of macroscopically discernible branches and anastomoses, their calibers, and the distance between the caudal main branches and the alveolar ridge recorded. The lateral maxilla is supplied by branches of the posterior superior alveolar artery (PSAA) and the infraorbital artery (IOA) that form an anastomosis in the bony lateral antral wall, which also supplies the Schneiderian membrane. This intraosseous anastomosis was found in all of the specimens. Eight of 18 also showed an extraosseous anastomosis between PSAA and IOA, vestibular to the antral wall, giving off an average of 3 branches cranially and 5 branches caudally. The two anastomoses form a double arterial arcade to supply the lateral antral wall and, partly, the alveolar process. The PSAA had a mean caliber of 1.6 mm and exhibited an average of 2 endosseous and 1 extraosseous branches. The IOA had a mean diameter of 1.6 mm and showed an average of 1 endosseous and 3 extraosseous branches. The mean distance between the intraosseous anastomosis and the alveolar ridge was 19 mm in 2 defined measuring sites. Its mean length was 44.6 mm. The epiperiosteal vestibular anastomosis was situated further cranially at a mean distance of 23 to 26 mm from the alveolar ridge and had a mean length of 46 mm. The rather large caliber of the vessels supplying the lateral antral wall seems to be crucial to the fact that the periosteal blood supply is maintained even in severe maxillary atrophy and after complete disappearance of the centro-medullary vessels.     

Phase I clinical trial with desoxypeganine, a new cholinesterase and selective MAO-A inhibitor: tolerance and pharmacokinetics study of escalating single oral doses

Desoxypeganine (DOP) is a natural alkaloid that has been characterized as a cholinesterase inhibitor and a selective inhibitor of monoamine oxidase A. DOP has been investigated for its potential utility in the pharmacological treatment of alcohol abuse and as a smoking cessation aid. The aim of this clinical trial was to evaluate the tolerance and single-dose pharmacokinetic profile of DOP in healthy human volunteers. The study was an open-label, dose-escalation, phase I clinical trial involving the administration of increasing single oral doses of DOP (50, 100, 150 and 200 mg). The study was conducted according to the Declaration of Helsinki and Good Clinical Practice. Eighteen healthy adult volunteers (8 males and 10 females, age ranging 20-30 years) were recruited. DOP was administered sequentially, escalating in single doses of 50, 100, 150 and 200 mg in four experimental sessions with a washout period of at least 1 week between them. Progress to the next dose was allowed only if the previous dose was tolerated. Pharmacokinetic parameters were determined using noncompartmental methods. Clinical and analytical safety was assessed throughout the study, and QTc intervals were measured at regular intervals. The main pharmacokinetic parameters and renal excretion are described. No serious adverse events were registered, and none of the subjects discontinued the study because of lack of tolerance. All the adverse events recorded were mild to moderate and increased with the dose. The ECG measurements revealed that even at a higher dose, the QTc interval remained below the safety threshold. In summary, this first phase I study indicates that DOP has linear and dose-proportional pharmacokinetics, satisfactory oral bioavailability and plasma half-life and renal excretion. Also, DOP has shown an adequate safety profile that allows the continuation of clinical development.     

Clinical and histologic evaluation of an enamel matrix protein derivative combined with a bioactive glass for the treatment of intrabony periodontal defects in humans

The present study clinically and histologically evaluated healing of human intrabony defects following treatment with a combination of enamel matrix derivative (EMD) and bioactive glass (BG) or BG alone. Six patients displaying either combined one- and two-walled (five patients) or three-walled (one patient) intrabony defects around teeth scheduled for extraction were included. A notch was placed at the most apical extent of the calculus on the root surface to serve as a reference. Six months after surgery, the teeth or roots were extracted, together with some of their surrounding soft and hard tissues, and processed for histologic evaluation; a gain of clinical attachment was found in all cases. Healing in all three defects treated with EMD + BG was mainly characterized by new cementum with inserting collagen fibers and new periodontal ligament; most graft particles were surrounded by bone-like tissue, indicating ongoing mineralization. Treatment with BG resulted in epithelial down-growth and connective tissue encapsulation of the graft material in all three specimens. Reformation of cementum and periodontal ligament was observed in one of the specimens, limited to the most apical part of the defect. Formation of bone-like tissue around the graft particles was observed in only one of the three specimens treated with BG. Direct contact between the BG particles and root surface (cementum or dentin) was not observed in any of the six specimens. BG alone has low potential to facilitate periodontal regeneration. However, EMD + BG resulted in formation of new cementum with an associated periodontal ligament, as well as enhanced mineralization around the BG particles.     

Exercise in severe COPD: Is walking different from stair-climbing?

BACKGROUND: It remains unclear whether the 6-min walking test can predict performance during stair-climbing in severe COPD patients. The present study aimed to assess different pathophysiological changes between walking and stair-climbing in these patients. METHODS: Sixteen COPD patients (mean FEV1 33+/-13% predicted) underwent a 6-min walking test and performed stair-climbing (44 steps) in a randomized, cross-over design. Blood gases, blood lactate, lung function parameters, maximal inspiratory mouth, sniff nasal and twitch mouth pressures, blood pressure, heart rate, and Borg Dyspnea Scale (BDS) were measured before and after exercise. RESULTS: The median drop of PaO2 during walking (2.6 mmHg) and stair-climbing (2.4 mmHg) was comparable (p=0.93). However, stair-climbing caused more dyspnea (median BDS 6.5 vs. 5.5, p=0.01), a higher median blood lactate (1.1 vs. 0.3 mmol/l p<0.001), a more pronounced drop in mean pH (-0.05+/-0.02 vs. -0.03+/-0.03, p=0.02) and a higher increase in mean systolic blood pressure (27+/-11 vs. 13+/-16 mmHg; p=0.009). Stair-climbing, but not walking, caused prolonged lung hyperinflation (mean TLC difference 4.4+/-4.7% predicted, p=0.003). There was no relationship between the 6-min walking distance (314+/-104 m) and the time needed for stair-climbing (55+/-33 s), nor were there any differences in inspiratory muscle strength and heart rate. CONCLUSION: Although the drop of PaO2 was comparable, stair-climbing resulted in more prolonged hyperinflation of the lungs, higher blood lactate production and more dyspnea than walking. The walking distance was not related to the time needed to manage stair-climbing. Therefore, pathophysiological changes during the 6-min walking test do not anticipate those during stair-climbing in patients with severe COPD.