Delta PP Research Articles

Hallux Valgus Interphalangeus Measurement: Comparison of the Two Radiographic Methods

Category: Midfoot/Forefoot Introduction/Purpose: To determine the reliability of Delta PP (difference in medial and lateral proximal phalanx wall length) compared to HIA (hallux interphalangeal angle) in the assessment of HVI (hallux valgus interphalangeus) in both pre and postoperative radiographs. Methods: This was a retrospective observational study of 186 feet with hallux valgus. The number of cases required to adequately power the study was 128. Preoperative and postoperative hallux alignment were evaluated by two different radiological parameters, Delta PP and HIA. Inter-observer variability was assessed independently by two authors and compared using a intraclass correlation coefficient. Results: The intra-class correlation coefficient was more than 0.8 for all parameters, thus both HIA and Delta PP measurement provide reliable and reproducible data. Mean HIA significantly increased following surgical correction of hallux valgus. In comparison, the mean Delta PP decreased after correction. This postoperative increase in HIA indicates that pre-operative HIA underestimates the magnitude of HVI and therefore is an inaccurate tool for measuring HVI's contribution to the TVDH (total valgus deformity of the hallux) and to preoperative planning. However, the Delta PP was a greater determinant of the phalanx deformity's contribution to the TVDH. Conclusion: The outcome of our study shows that both HIA and Delta PP are reproducible when assessing the hallux valgus interphalangeus deformity, however, Delta PP quantifies the amount of correction obtained more precisely. The additional benefit of measuring the Delta PP is that it allows for accurate planning in determining the dimensions of the medial based wedge of the Akin osteotomy that needs to be resected.

Hallux Valgus Interphalangeus Measurement: Comparison of the 2 Radiographic Methods.

To determine the reliability of Delta PP (difference in medial and lateral proximal phalanx wall length) compared with HIA (hallux interphalangeal angle) in the assessment of HVI (hallux valgus interphalangeus) in both preoperative and postoperative radiographs. This was a retrospective observational study of 186 feet with hallux valgus. The number of cases required to adequately power the study was 128. Preoperative and postoperative hallux alignment were evaluated by 2 different radiological parameters, Delta PP and HIA. Interobserver variability was assessed independently by 2 authors and compared using a intraclass correlation coefficient. The intraclass correlation coefficient was more than 0.8 for all parameters, thus both HIA and Delta PP measurement provide reliable and reproducible data. Mean HIA significantly increased following surgical correction of hallux valgus. In comparison, the mean Delta PP decreased after correction. This postoperative increase in HIA indicates that preoperative HIA underestimates the magnitude of HVI and therefore is an inaccurate tool for measuring HVI's contribution to the TVDH (total valgus deformity of the hallux) and to preoperative planning. However, the Delta PP was a greater determinant of the phalanx deformity's contribution to the TVDH. The outcome of our study shows that both HIA and Delta PP are reproducible when assessing the HVI deformity; however, Delta PP quantifies the amount of correction obtained more precisely. The additional benefit of measuring the Delta PP is that it allows for accurate planning in determining the dimensions of the medial-based wedge of the Akin osteotomy that needs to be resected. Level 4.

Effect of pneumoperitoneum on dynamic variables of fluid responsiveness (Delta PP and PVI) during Trendelenburg position.

Background and Aims:Pulse pressure variation (ΔPP) is considered as one of the best predictors of fluid responsiveness in patients under mechanical ventilation. Pleth Variability Index (PVI) has been proposed as a noninvasive alternative. However, pneumoperitoneum has been recently suggested as a limitation to their interpretation. The aim of this study was to compare changes in ΔPP and PVI related to autotransfusion associated with a Trendelenburg maneuver before and during pneumoperitoneum.Methods:50 patients undergoing elective abdominal laparoscopic surgery were enrolled in this prospective observational study. All patients were equipped with an invasive radial artery catheter and a PVI probe. After obtaining a stable signal with both ΔPP and PVI, baseline values were recorded, before and after head-down tilts of 10°, with or without abdominal insufflation (10-12 mmHg). All measurements were made before any fluid challenge under standardized anaesthesia, while patients were paralyzed and mechanically ventilated with 8 mL/kg tidal volume.Results:Changes in ΔPP and PVI associated with the Trendelenburg maneuver before and after insufflation of the pneumoperitoneum were significantly different (P < 0.001). In baseline conditions, the Trendelenburg maneuver was associated with a significant decrease in heart rate while mean arterial pressure remained unchanged. Both ΔPP and PVI decreased. After insufflation of the pneumoperitoneum, the Trendelenburg maneuver was associated with a significant decrease in heart rate and ΔPP and an increase in mean arterial pressure while PVI remained unchanged.Conclusion:Pneumoperitoneum did not alter the response of ΔPP to autotransfusion associated with the Trendelenburg maneuver, which was not the case for the PVI. This latter decreased during Trendelenburg maneuver performed alone and remained unchanged during Trendelenburg maneuver performed after insufflation of the pneumoperitoneum.

Radiographic Analysis Between Two Commonly Used Measurements for Hallux Valgus Interphalangeus

Category:BunionIntroduction/Purpose:There is an increasing recognition of the contribution of hallux valgus interphalangeus (HVI) to the total deformity seen in hallux vallux valgus. The most commonly assessed radiological parameter is the hallux interphalangeus angle (HIA). Our aim in this study was to assess the reliability of the difference in medial and lateral proximal phalanx wall length (delta PP) in the assessment of hallux valgus interphalangeus in both the pre-operative and post-operative radiographs compared with the HIA.Methods:All patients undergoing scarf osteotomy for hallux valgus correction at our institution over a nine-month period were included. 40 feet in 36 patients were evaluated. Standard AP weight bearing radiographs preoperative and at 6 weeks post-surgery were evaluated by 2 independent observers. The standard PACS angular measurement tools were used for all measurements. The HIA and delta PP were measured along with hallux valgus angle (HVA) and intermetatarsal angle (IMA). Delta PP was calculated as the medial side length of the medial proximal phalanx minus the lateral side length of the proximal phalanx. SPSS 21 was used for statistical evaluation. Two-way random single measure intra-class correlation coefficient (ICC) was calculated to assess the interobserver agreement.Results:33 female and 3 male patients were assessed. The mean age was 58 years (range 26-80 years). 18 patients underwent an Akin osteotomy. Pre-operative mean HVA 33 degrees, IMA 15 degrees, HIA 4 degrees and delta PP 1.64 mm. Post-operative mean HVA 17 degrees, IMA 9 degrees, HIA 7 degrees and delta PP 1.03 mm. In the sub group that underwent an Akin osteotomy the HIA increased from 5.2 degrees to 8.8 degrees in contrast to the delta PP that reduced from 2.04 to 0.26 mm.Pre-operatively the inter observer agreement using ICC was HVA 0.74, IMA 0.82, HIA 0.65 and Delta PP 0.70. Postoperatively the interobserver agreement was HVA 0.71, IMA 0.55, HIA 0.57 and Delta PP 0.64.Conclusion:The delta PP was more reliable than the HIA, with an improved interclass agreement on both pre and post- operative radiographs. The mean post-operative HIA increased, this was also present in the group where an akin osteotomy had been performed. In contrast the delta PP reduced. We feel pronation of the toe may alter the radiographic measures for HVI assessment and affect the validity of the HIA measurements, however the delta PP reliability was less affected.Pre-operative radiographs had greater interobserver agreement across all measures than postoperative radiographs, which may reflect difficulties in determining the bony landmarks for measurement following surgery.

Effect of the pneumoperitoneum on dynamic variables Delta PP and PVI during Trendelenburg position

Effect of the pneumoperitoneum on dynamic variables Delta PP and PVI during Trendelenburg position

Central venous pressure measurements improve the accuracy of leg raising-induced change in pulse pressure to predict fluid responsiveness

Passive leg raising (PLR) is a maneuver performed to test the cardiac Frank-Starling mechanism. We assessed the influence of PLR-induced changes in preload on the performance of PLR-induced change in pulse pressure (Delta(PLR)PP) and cardiac output (Delta(PLR)CO) for fluid responsiveness prediction. Sedated, nonarrhythmic patients with persistent shock were included in this prospective multicenter study. Cardiac output and pulse pressure were measured at baseline (patient supine), during PLR (lower limbs lifted to 45 degrees) and after 500-ml volume expansion. Patients were classified as responders or not. In the whole population (n = 102), the area under the receiver-operating characteristic curve (AUC) was 0.76 for Delta(PLR)PP and was higher for Delta(PLR)CO (0.89)(p < 0.05), but likelihood ratios were close to 1. In patients with a PLR-induced increase in central venous pressure (CVP) of at least 2 mmHg (n = 49), Delta(PLR)PP and Delta(PLR)CO disclosed higher AUCs than in the rest of the population (0.91 vs. 0.66 and 0.98 vs. 0.83; p < 0.05); positive/negative likelihood ratios were 9.3/0.14 (8% cutoff level) and 30/0.07 (7% cutoff level), respectively. A PLR-induced change in CVP > or =2 mmHg was required to allow clinical usefulness of PLR-derived indices. In this situation, Delta(PLR)PP performed well for predicting fluid responsiveness in deeply sedated patients.

Simplified Method to Measure Respiratory-Related Changes in Arterial Pulse Pressure in Patients Receiving Mechanical Ventilation

Measuring respiratory-related changes in arterial pulse pressure is useful to guide fluid expansion in hemodynamically compromised patients. In the absence of automation, this can be uneasy in clinical practice. The objective of this study was to test an alternative approach (expiratory pause) that should be easier to apply. Prospective observational study comparing two measurement methods of a biological variable. Seventeen patients receiving mechanical ventilation without spontaneous respiratory activity, with an arterial indwelling catheter, exhibiting respiratory-related fluctuations in arterial pressure. Ten-bed respiratory ICU in a 2,000-bed university hospital. Analysis of clinically gathered data without specific experimental intervention. Determinations of the change in arterial pulse pressure observed during ventilatory cycling (Delta Pp,dyn) ["dynamic"] and change in arterial pulse pressure observed during expiratory pauses (Delta Pp,stat) ["static"] were performed to assess respiratory mechanics, and comparison of the two sets of data (correlation, Bland and Altman, Passing and Bablok regression). Delta Pp,dyn and Delta Pp,stat were strongly correlated (R = 0.964; 95% confidence interval, 0.917 to 0.987; p < 0.0001), with a good level of agreement (mean difference, 0.016; lower limit of agreement, - 0.087; upper limit, 0.120) and no systematic difference. Measuring respiratory-related Delta Pp,stat provides data that seem interchangeable with Delta Pp,dyn, providing an easy means to routinely obtain this information.

Predicting Fluid Responsiveness in ICU Patients: A Critical Analysis of the Evidence

To identify and critically review the published peer-reviewed, English-language studies investigating predictive factors of fluid responsiveness in ICU patients.Studies were collected by doing a search in MEDLINE (from 1966) and scanning the reference lists of the articles. Studies were selected according to the following criteria: volume expansion performed in critically ill patients, patients classified in two groups (responders and nonresponders) according to the effects of volume expansion on stroke volume or on cardiac output, and comparison of responder and nonresponder patients' characteristics before volume expansion.Twelve studies were analyzed in which the parameters tested were as follows: (1) static indicators of cardiac preload (right atrial pressure [RAP], pulmonary artery occlusion pressure [PAOP], right ventricular end-diastolic volume [RVEDV], and left ventricular end-diastolic area [LVEDA]); and (2) dynamic parameters (inspiratory decrease in RAP [Delta RAP], expiratory decrease in arterial systolic pressure [Delta down], respiratory changes in pulse pressure [Delta PP], and respiratory changes in aortic blood velocity [Delta Vpeak]). Before fluid infusion, RAP, PAOP, RVEDV, and LVEDA were not significantly lower in responders than in nonresponders in three of five studies, in seven of nine studies, in four of six studies, and in one of three studies, respectively. When a significant difference was found, no threshold value could discriminate responders and nonresponders. Before fluid infusion, Delta RAP, Delta down, Delta PP, and Delta Vpeak were significantly higher in responders, and a threshold value predicted fluid responsiveness with high positive (77 to 95%) and negative (81 to 100%) predictive values.Dynamic parameters should be used preferentially to static parameters to predict fluid responsiveness in ICU patients.

Functional and desensitizing effects of the novel synthetic vanilloid-like agent 12-phenylacetate 13-acetate 20-homovanillate (PPAHV) in the perfused rat hindlimb.

1. In the present study, the effects of the novel vanilloid agonist, 12-phenylacetate 13-acetate 20-homovanillate (PPAHV), on oxygen consumption (VO(2)) and vascular resistance (perfusion pressure, PP) were investigated in the constant flow, perfused rat hindlimb. The acute desensitizing properties of this novel synthetic agent were also examined. 2. Maximum stimulation of VO(2) was produced by 0.2 microM PPAHV (delta VO(2), 0.83+/-0.06 micromol g(-1) h(-1)) and was accompanied by mild vasoconstriction (increase in PP; 8.0+/-1.1 mmHg). The highest concentration of PPAHV tested (2 microM) caused inhibition of VO(2) (delta VO(2), -2.73+/-0.51 micromol g(-1) h(-1)) and strong vasoconstriction (delta PP, 42.0+/-1.2 mmHg). 3. Capsazepine (10 microM) caused a parallel shift to the right of both VO(2) and PP concentration-response curves for PPAHV (pK(b)=5.00), indicative of competitive binding to vanilloid receptors. 4. The stimulation of VO(2) produced by 0.2 microM PPAHV decreased, but was not completely abolished, after repeated infusion of PPAHV (change in VO(2), first infusion, 0.66+/-0.18 micromol g(-1) h(-1); sixth infusion, 0.29+/-0. 08 micromol g(-1) h(-1), P<0.05), an acute tachyphylactic response not previously seen with the repeated infusion of other vanilloid analogues. Conversely, the PP response to repeated PPAHV infusion increased (delta PP, first infusion, 5.8+/-0.7 mmHg; sixth infusion, 9.0+/-0.6 mmHg, P<0.05). 5. In conclusion, PPAHV produces vasoconstriction and a biphasic effect on VO(2) in the perfused rat hindlimb very similar to that induced by naturally occurring vanilloids. Both effects are blocked by the competitive antagonist capsazepine. Since, the metabolic response to low concentrations of PPAHV (stimulation of VO(2)) undergoes tachyphylaxis, the present data suggest that PPAHV desensitizes putative vanilloid receptors in the hindlimb.

Polyurethane foam sheets for relieving pressure from diabetic neuropathic plantar ulcers: a pilot study

INTRODUCTION: Lesions of the diabetic neuropathic foot are mainly caused by pressure in anatomically altered areas. This leads to hyperkeratosis, skin disruption and finally to ulcerations that can progress to underlying bone. Therapy for plantar neuropathic ulcerations in diabetic patients involves relieving pressure from ulcerated areas to allow re-epithelialization. Traditional methods, such as casts, orthoses and special shoes, are not well tolerated by patients. OBJECTIVE: To test whether polyurethane foam sheets, regularly used for dressing neuropathic ulcers of the diabetic foot, may also play a role in pressure relieving, we conducted a pilot study in a group of neuropathic diabetic outpatients. METHODS: Ten diabetic patients with non-complicated neuropathic plantar ulcerations were consecutively selected among the attenders of our diabetic foot clinic. The patients underwent careful debridement of the ulcerated area and elimination of perilesional hyperkeratosis. The ulcers were then covered with semipermeable film to allow measurements to be made. An evaluation of static and dynamic plantar pressure was then performed with F-SCAN, specialized software that analyses data collected from two 960-LED insoles (one for each foot). Static plantar pressures were acquired after patients had stood still on both feet for 15 s, while dynamic pressures were measured after walking for 2 min. The same evaluations were performed after positioning over and around the ulcers a double layer of polyurethane foam sheeting (Allevyn Adhesive) tailored to adapt to the conformation of the foot. The following parameters were then evaluated: peak pressure (PP: kPa); areas of peak pressure (APP:cm 2 ); time of application of peak pressure (TPP:s). RESULTS: The PP was significantly lower after application of the polyurethane sheeting (P<0.01), while the APP significantly increased (P<0.001). No significant differences were observed for TPP. Differences in PP (Delta PP) and in APP (Delta APP) were then calculated: Delta PP significantly inversely correlated with Delta APP, both in static and in dynamic conditions (P<0.001). CONCLUSION: Polyurethane foam sheets proved to be effective in reducing plantar pressures in neuropathic feet, probably because of an increased area of pressure distribution. Further studies are necessary to verify whether the use of this material could actually reduce the healing time of neuropathic ulcers in diabetic patients. (J Dermatol Treat (2000) 11:39–42)

Effect of ischaemic preconditioning on vascular dysfunction induced by ischaemia and reperfusion in rat hindquarters.

The aim of this study was to examine the effect of ischaemia on vascular responses to endothelium-dependent and endothelium-independent vasodilators and on vasoconstrictor responses. Furthermore, the ability of preconditioning to prevent ischaemia-induced changes in vascular reactivity was examined in the rat hindquarters. The abdominal aortae of anaesthetized rats were cannulated for hindquarters perfusion with Krebs bicarbonate solution containing phenylephrine to induce vasoconstrictor tone. Responses of the hindquarters to endothelium-dependent and endothelium-independent vasodilators were examined. Hindquarters responses to neuronal release of the vasodilator acetylcholine (ACh) induced by peri-aortic nerve stimulation were also examined. Ischaemia with 2 h aortic occlusion prior to Krebs perfusion attenuated vasodilator responses to the neuronal release of ACh [10 Hz; decrease in perfusion pressure (delta PP) control: -18(s.e.m. 3) mmHg, Ischaemic: -13(3) mmHg], exogenous ACh [10 ng; delta PP control: -22(2) mmHg, ischaemic: -17(2) mmHg] and carbachol [1.0 micrograms; delta PP control: -21(3) mmHg, ischaemic: -12(3) mmHg]. Responses to other endothelium-dependent vasodilators bradykinin and histamine or the endothelium-independent vasodilator, sodium nitroprusside, were not impaired by ischaemia. Similarly vasoconstriction to noradrenaline and serotonin was not affected. Ischaemia preceded by preconditioning with 5 min aortic occlusion and 10 min reperfusion prevented impairment of vasodilatation to nerve stimulation [1.0 micrograms; delta PP preconditioned: -24 (3) preconditioned: -20(1) mmHg], ACh [10 ng; delta PP preconditioned: -22(1) mmHG] and carbachol [1.0 micrograms; delta PP preconditioned: -24(3) mmHG]caused by ischaemia. These data indicate that hindquarters ischaemia causes selective impairment of dilator responses to muscarinic agonists and ischaemic preconditioning prevents that impairment.

Nicardipine Inhibits the Endothelin-1-Induced Constriction of Systemic Capacitance and Resistance Vessels

We estimated the effects of intravenous injection of endothelin-1 (ET-1; 400 pmol/kg) on the systemic capacitance and resistance vessels in anesthetized mongrel dogs by measuring changes in the mean circulatory pressure (MCP) and total peripheral resistance (TPR), respectively. In addition, the present study investigated the inhibiting action of nicardipine (NIC; 10 micrograms/kg bolus injection followed by 1.0-2.0 micrograms/kg/min continuous infusion) against the vasoconstrictor action of ET-1. We examined the effects of ET-1 (30 to 1,000 pmol/0.1 ml) on the femoral arterial system by measuring the percent changes in the perfusion pressure (% delta PP) of the femoral artery perfused with a constant flow, and investigated the effect of NIC on the vasoconstrictor action of ET-1 in this preparation. We obtained the following results: (a) Intravenous injection of ET-1 raised both TPR and MCP. However, in the presence of NIC, ET-1 raised TPR without influencing MCP. (b) Intra-arterial injection of ET-1 caused a dose-dependent increase in % delta PP. NIC shifted the dose-response curve of ET-1 for % delta PP to the right in a parallel fashion.

Theoretical model of ventricular interdependence: pericardial effects

One ventricle can influence the filling characteristics of the opposite ventricle directly through the myocardium and indirectly through the pericardium. Based on definitions of compliances and volumes, we developed a theoretical analysis that indicated that the magnitude of interdependence was related to the relative compliances of the left and right ventricular free walls, septum, and pericardium. This analysis was verified in postmortem canine hearts. Balloons were inserted into each ventricle, and left ventricle pressure (delta Pl) and volume (delta Vl) changes caused by increasing right ventricular pressure (delta Pr) and volume (delta Vr) or pericardial pressure (delta Pp) were recorded. For delta Pl/delta Pr, delta Pl/delta Pp, delta Pl/delta Vr, delta Vl/delta Pr, delta Vl/delta Pp, and delta Vl/delta Vr measurements, the standard error of estimates was small and the predicted and measured values were significantly related (P less than 0.05); the values were 0.88 +/- 0.16, 0.87 +/- 0.17, 0.93 +/- 0.05, 0.95 +/- 0.09, 0.96 +/- 0.05, and 0.96 +/- 0.04, respectively. These coupling coefficients (delta Pl/delta Pr, delta Pl/delta Pp, etc.) a direct measurement of interdependence, indicated that pericardial-to-ventricular coupling is greater than ventricular-ventricular coupling (delta Pl/delta Pp greater than delta Pl/delta Pr, 0.91 +/- 0.09 vs. 0.23 +/- 0.09, P less than 0.01; delta Vl/delta Pp greater than delta Vl/delta Pr, -1.04 +/- 0.35 vs. -0.19 +/- 0.05, P less than 0.05). This study, by developing a theoretical analysis and by direct measurements, provides a better understanding of ventricular interdependence and may help to predict effects of cardiac tamponade and constrictive pericarditis on ventricular interdependence.

Augmentation of pulmonary blood flow after right ventricular bypass

We have studied pulmonary hemodynamics after right ventricular bypass in dogs. Manipulations of pulmonary vascular resistance and transpulmonary blood pressure difference (delta Pp) made it possible to increase pulmonary blood flow. Decreasing resistance by raising arterial pH from 7.25 to 7.38 increased flow by 24.9%. Infusion of homologous blood to increase right atrial pressure from 10 to 30 mm Hg lowered resistance 41.5% and raised flow 183%. Left ventricular bypass (left atrium to aorta) lowered left atrial pressure, increased arteriovenous pressure gradient by 41.4%, and raised flow 32.8%. These experiments support earlier clinical observations of the importance of low pulmonary vascular resistance and of good left ventricular function both in selection of patients and in postoperative management after right ventricular bypass. Attention to the principles we discuss may permit right ventricular bypass operation in some patients who would not be operable by current criteria.

Role of the small intestine and gastric antrum in pancreatic polypeptide release

Gastrointestinal peptides have been proposed to play an important role in the pancreatic polypeptide response to a meal. These studies examine the role of the small intestine and gastric antrum in pancreatic polypeptide release in unanesthetized dogs. Intestinal perfusion with 5% liver extract in seven dogs resulted in a significant increase (P less than 0.05) in serum pancreatic polypeptide concentration (mean delta PP = 35.0 +/- 10.5 pM). Antrectomy without truncal vagotomy in four of these dogs significantly inhibited (P less than 0.05) this response. In five other dogs, antrectomy inhibited the pancreatic polypeptide response to an ingested meat meal by 81.9 +/- 4.5% (P less than 0.01). To further delineate the mechanism by which antrectomy inhibits pancreatic polypeptide release, the pancreatic polypeptide response to a meal was measured in four dogs before and after selective antral denervation. Antral denervation inhibited pancreatic polypeptide release to a degree similar (81.5 +/- 13.4%) to that previously observed after antrectomy. These studies have demonstrated an intestinal phase of pancreatic polypeptide release. They also suggest that antrectomy exerts its inhibitory effect on pancreatic polypeptide release by partially denervating the pancreas.