Post-suction recruitment manoeuvre restores lung function in healthy, anaesthetized pigs.

Endotracheal suction can cause partial lung collapse and hypoxia and alter lung mechanics. We investigated the effects of adding a recruitment manoeuvre directly after endotracheal suction to restore lung volume in volume-controlled ventilation and pressure-controlled ventilation modes. Five anaesthetized pigs were investigated. The effects of endotracheal suction with or without a recruitment manoeuvre were compared in random order. In volume-controlled ventilation, compliance decreased after suction from 33 +/- 5 to 26 +/- 6 ml x cmH2O(-1) (P<0.05), and 30 minutes later it remained decreased at 25 +/- 6 ml x cmH2O(-1). Venous admixture increased after suction from 5 +/- 2 to 8 +/- 4% (P<0.05), but had recovered at 30 minutes. In pressure-controlled ventilation, compliance decreased after suction from 34 +/- 3 to 25 +/- 7 ml x cmH2O(-1) (P<0.05), and 30 minutes later it remained decreased at 25 +/- 7 ml x cmH2O(-1). Venous admixture increased after suction from 5 +/- 2 to 13 +/- 7% (P<0.05), and had not recovered after 30 minutes, 10 +/- 4%. When a recruitment manoeuvre was applied directly after suction, no negative side-effects were registered in volume-controlled ventilation or pressure-controlled ventilation. We conclude that the impairment of lung mechanics and gas exchange induced by endotracheal suction can be prevented by a simple post-suction recruitment manoeuvre. Further studies are needed to identify a suitable suction recruitment manoeuvre in patients with diseased lungs.

The influence of distal runoff on patency of infrainguinal vein bypass grafts.

This retrospective study was conducted to analyze a new concept of evaluation of the effect of distal runoff on patency in infrainguinal bypass surgery for arterial insufficiency. Distal runoff was evaluated on postreconstruction angiograms in 191 limbs undergoing femoropopliteal and femorodistal reconstruction. Runoff was characterized as good, fair, or poor. Determination of graft patency was made by clinical examination, ankle-brachial index measurement, or duplex scanning at 1 month and thereafter at 6-month intervals. Cumulative patency rates were calculated according to the actuarial life table method. Patency rates in limbs with good runoff were better than in limbs with fair and poor runoff; at 6 months, patency rates were 88.2%, 70.9%, and 21.8%, respectively (p < 0.01). Similar patency rates were found for good runoff in femoropopliteal and femorodistal reconstructions (84.7% in femoropopliteal and 75% in femorodistal reconstructions) at 6 months. The authors conclude that this method of angiographic evaluation accurately predicts patency in infrainguinal bypass reconstructions.

A multivariate analysis of factors affecting patency of femoropopliteal and femorodistal bypass grafting.

BACKGROUND: The most important factors that determine the outcome after femoropopliteal and femorodistal arterial reconstruction are still controversial. This report analysis the factors that determine the early and late patency of distal arterial reconstruction. PATIENTS AND METHODS: A retrospective analysis of patency after femorodistal arterial reconstruction with a new method for evaluation of angiographic runoff was performed for 336 arterial reconstructions. The different pre-, per- and postoperative risk factors were analysed in a Cox proportional hazards model. RESULT: The patency was significantly better for vein grafts in comparison to composite grafts and prosthetic grafts. It was 74% for vein, 46% for composite and 43% for prosthetic reconstructions, respectively, at 12 months after arterial reconstruction. The cumulative life table patency rate in extremities with good, intermediate and poor runoff was 62, 30 and 10%, respectively at 36 months. The patency rates for extremities operated on for claudication was significantly better than for extremities operated on for critical ischaemia. The multivariate analysis of different factors in a Cox analysis revealed that only the status of distal runoff, the graft material and the site of the distal anastomosis independently and significantly influenced the patency rates. CONCLUSIONS: A new model for evaluation of distal runoff proved to predict the patency rate of femoropopliteal and femorodistal arterial reconstructions reasonably well in this retrospective analysis.

Influence of twist on vein and PTFE graft hemodynamics: an ex vivo experimental study.

OBJECTIVE: In an ex vivo infusion model, the effect of different factors affecting the critical level of twist in vein and PTFE grafts was analysed. SETTING: University Hospital, Department of Surgery. EXPERIMENTAL DESIGN: Saline perfusion of grafts with various diameter and length under constant high (90 ml/min) and low (50 ml/min) flow rates against various peripheral resistance was performed. MEASURES: The pressure changes in the grafts were measured at increasing increments of twisting. RESULTS: The critical level of twist appears to be dependent on the diameter, length, stretching, status of peripheral resistance, amount of volume flow and the type of graft material, varying between 90 to more than 360 degrees. In vein grafts critical twisting appeared earlier with a decrease in diameter, shortening in length, high peripheral resistance, high flow rate and stretching. PTFE grafts especially with external spiral support were resistant to twist. CONCLUSIONS: These data suggest that the critical level of graft twist is dependent upon multiple factors and moderate or even high grade twist with especially externally supported PTFE grafts regardless of length and long mobilized vein grafts do not lead to hemodynamic changes. On the other hand total cessation of flow occurs at lower degrees of twist in stretched, short vein grafts.

The use of below-knee percutaneous transluminal angioplasty in arterial occlusive disease causing chronic critical limb ischemia.

PURPOSE: To determine the efficacy, safety and long-term results of crural artery percutaneous transluminal angioplasty (PTA) in limbs with chronic critical limb ischemia (CLI). METHODS: Patients undergoing crural artery PTA due to CLI were followed at regular clinic visits with ankle brachial pressure index (ABPI) measurements. PTA of the crural arteries was attempted either alone (n = 39) or in combination with PTA of the superficial and/or popliteal artery (n = 55) in 86 limbs (82 patients and 94 procedures) presenting with CLI. The ages of patients ranged from 37 to 94 years (mean 72 years). The indications for PTA were rest pain in 10 and ulcer/gangrene in 84 limbs. RESULTS: A technically successful PTA with at least one crural level was achieved in 88% of cases (n = 83). Cumulative primary clinical success rates at 6, 12, 24, and 36 months were 55%, 51%, 36%, and 36%, respectively. Cumulative secondary clinical success and limb salvage rates at 36 months were 44% and 72%, respectively. CONCLUSION: PTA of the crural arteries might be considered the primary choice of treatment in patients with CLI and distal lesions with localized stenosis or segmental short occlusions.

Patterns of atherosclerotic occlusive disease of lower leg and pedal arteries in hypertensive patients undergoing infrainguinal bypass procedures.

OBJECTIVE: To analyse the atherosclerotic involvement of lower leg and foot arteries in patients undergoing infrainguinal bypass grafting. SETTING: Department of Surgery, University Hospital. PATIENTS: Among 282 limbs (267 patients), fifty limbs belonged to hypertensive nondiabetics (Group A), 39 to hypertensive diabetics (Group B), 129 to normotensive nondiabetics (Group C) and 64 to normotensive diabetics (Group D). INTERVENTIONS: Femoropopliteal or femorodistal bypass procedures. MEASURES: Intraoperative postreconstruction serial angiography of the lower leg and foot arteries. RESULTS: Occlusion rate of two or three lower leg arteries was significantly higher among diabetics (Group B 77% and Group D 73%, respectively) compared to nondiabetics (Group A 56% and Group D 51%, respectively). It was similar in diabetic patients with or without hypertension. The incidence of having both foot arches (dorsal and plantar arch) intact was significantly higher in nondiabetic patients with hypertension (Group A). Only 5.8% of these patients demonstrated both deficient or occluded foot arches compared to 18% in Group B and 31% in Group C and 20% in Group D. CONCLUSION: Hypertension does not seem to contribute to the extent and severity of lower leg and foot vessel involvement in patients undergoing infrainguinal bypass surgery.

A modified technique of ultrasonic triplex scanning of the lower extremity arteries.

This study was undertaken to evaluate the utility of a modified technique of triplex scanning of the lower extremity arteries in 20 subjects without any clinical signs of arterial disease. The distal aorta and iliac arteries were examined with the subject in supine position and lying slightly on the opposite side. By moderate compression of the probe towards the psoas muscle and directing it over the iliac arteries with slight medial retraction of the abdomen, satisfactory visualization of the common and external arteries with 7.5 MHz high resolution imaging and a 5.6 MHz doppler probe were obtained in 56 of 80 segments (70%). In obese individuals it was necessary to use 5 MHz probe for satisfactory scanning of the aortic bifurcation and common iliac arteries. The distal superficial femoral, popliteal and tibioperoneal trunk segments were examined with the patient prone and the knee slightly flexed. Peak systolic, early diastolic reverse and late diastolic forward flow velocities were studied together with measurement of the arterial diemeters, which demonstrated wide variations. This study suggests that satisfactory scanning of the iliac and femoropopliteal arteries with the described technique can be achieved in the majority of subjects with a superficial high resolution probe. The combination of 7.5 MHz two-dimensional imaging with a 5.6 MHz pulsed wave Doppler probe offers optimal information of these arteries in nonobese individuals.

Reduction of requirement for leg vascular surgery during long-term treatment of claudicant patients with ticlopidine: results from the Swedish Ticlopidine Multicentre Study (STIMS).

OBJECTIVE: To study the effect of long-term treatment of the platelet inhibitor ticlopidine as secondary prevention against the need of vascular surgery in patients with intermittent claudication. DESIGN: The Swedish Ticlopidine Multicentre Study (STIMS), was conducted in six medical and surgical clinics of university hospitals in Sweden. METHODS: 687 claudicants were randomised to ticlopidine 250 mg bd or placebo and vascular surgery events were recorded prospectively over a 7-year period. Cox proportional hazards models of risk for leg vascular surgery were constructed using drug treatment and 11 putative risk factors for vascular disease as covariates. Surgical event-free survivals were compared by Kaplan-Meier analysis. RESULTS: The overall rate of first operations was 2.4% per annum. More than half of these operations were in the aortoiliac region. One-quarter of patients operated during the period required further operations but amputation was rare. Ticlopidine treatment reduced the need for vascular reconstructive surgery by about half, both in intention-to-treat and on-treatment analyses (unadjusted relative risks 0.486, 95% CI 0.317-0.745; p < 0.001; 0.493, 95% CI 0.290-0.841: p < 0.01, respectively). In Cox model analysis only male sex was confirmed as a risk factor for surgery. Previous peripheral arterial surgery was the strongest predictor of the need for surgery. None of the risk factors examined interacted statistically with the effect of treatment with ticlopidine. CONCLUSION: In patients with intermittent claudication it seems possible to prevent the need for future vascular surgery by the use of platelet inhibition with ticlopidine.

Comparative analysis of patency, limb salvage and survival in diabetic and non-diabetic patients undergoing infrainguinal bypass surgery.

In 92 diabetic and 175 non-diabetic patients undergoing 336 femoropopliteal or femorodistal bypass procedures, 1- and 3-year cumulative life-table patency, limb salvage, and survival rates were comparatively analysed. The peroperative mortality rate was significantly higher in diabetic patients (5% compared to 1.4%, p < 0.001). The cumulative graft patency rates were 61% at 12 months and 46% at 36 months in diabetic patients compared to 64 and 52% in non-diabetic patients. Significantly better patency rates were observed in limbs with good runoff compared to limbs with poor runoff in both groups. The limb salvage rates at 3 years were 70% in diabetic patients and 62% in non-diabetic patients. The survival rate at 3 years was significantly lower in diabetic patients, 62% compared to 86% in non-diabetic patients. Diabetic patients with poor runoff demonstrated a significantly lower survival rate after 36 months compared to diabetic patients with good runoff (48% and 74%, respectively). The results of this study demonstrate that the early and intermediate patency and limb salvage rates are similar in diabetic and non-diabetic patients. On the other hand the survival rate in diabetic patients, especially in those with poor distal runoff, is significantly lower than non-diabetic patients.

Renal biopsy in children: indications, technique and efficacy in 119 consecutive cases.

Consecutive renal biopsies were performed on native kidneys in 109 children and adolescents, aged 0.1-19.8 (mean 9.9) years (119 biopsies). Bleeding diatheses were excluded or treated pre-operatively with intravenous desmopressin acetate. Biopsies were performed by a radiologist under ultrasound imaging, using an automated spring-loaded device allowing selection of the length of the needle movement and score size. Diagnostically adequate tissue was retrieved in 118 of 119 (99.2%) biopsy procedures; 24-h post-biopsy ultrasonography disclosed a small haematoma of the biopsied kidney in 26% of the cases. No correlation was seen between the occurrence of haematoma and (treated) prolonged bleeding time or a decrease in the haemoglobin level. No major complications occurred. Newly developed macroscopic haematuria was reported by 7% and micturition pain by 7% of patients. Painful body movements were reported by 37%. We conclude that the use of ultrasound imaging and an automated gunshot technique is a safe and efficient method for performing renal biopsies in paediatric patients.

The effect of postocclusion reactive hyperaemia, papaverine and nifedipine on duplex derived haemodynamic parameters of infrainguinal bypass grafts.

OBJECTIVES: The aim of the present study was to analyse the effects of various vasodilating stimuli on postoperative infrainguinal graft haemodynamics. DESIGN: Duplex derived haemodynamic parameters of infrainguinal bypass grafts were measured at rest and after postocclusion reactive hyperaemia, intraarterial papaverine (40 mgm) injection and peroral nifedipine (10 mg) administration. SETTING: Department of Surgery, University Hospital. MATERIALS: Twenty-nine patients with infrainguinal bypass grafts were studied by Duplex scanner after a median of 25 months postoperatively. CHIEF OUTCOME MEASURES: Peak systolic velocity (PSV), mean velocity (MV) and volume flow (VF) were measured at rest and after various stimuli. MAIN RESULTS: VF at rest increased from 125 +/- 16 ml/min (mean +/- S.E.M.) to 271 +/- 26 ml/min after papaverine administration and to 205 +/- 19 ml/min during reactive hyperaemia (p < 0.001). PSV, MV and VF increased significantly during postocclusion reactive hyperaemia and papaverine injection. After nifedipine administration VF increased to 154 +/- 21 ml/min after 30 min (p < 0.001) and there was a significant increase in MV (p < 0.05). CONCLUSIONS: Duplex derived flow measurement of infrainguinal bypass grafts can evaluate graft and limb haemodynamics in the postoperative period. Pharmacological manipulations, such as vasodilation, can influence the physiological runoff with subsequent increase in volume flow through the graft.

Duplex ultrasound scanning for diagnosis of aortoiliac and femoropopliteal arterial disease.

Forty patients with symptomatic aortoiliac and/or femoropopliteal occlusive arterial disease subjected to angiography were studied with duplex ultrasonography. The duplex scanning of the aortic, iliac, femoral and popliteal segments had a sensitivity of 93% in detecting significant stenoses and a specificity of 91%. The positive and negative predictive values were 75% and 98%, respectively. The sensitivity was relatively low in low-flow segments distal to total occlusions especially in patients with severe iliac disease and multiple distal femoropopliteal lesions. The results demonstrate the reliability of duplex scanning in detecting aortoiliac and femoropopliteal lesions.

Bypass grafting to the popliteal artery in limbs with occluded crural arteries.

Intraoperative completion angiograms of 47 femoropopliteal bypasses in limbs with occluded crural arteries were reviewed to identify the angiographic determinants of early outcome. Of 28 limbs in which the foot vessels were available for analysis, only 2 (7%) had an intact pedal circulation, and 18 limbs demonstrated no crural arteries suitable for distal reconstruction. The overall cumulative patency rate was 51% with a 76% limb salvage rate at 12 months. All seven grafts performed onto a popliteal artery segment of less than 8 cm occluded in the early period. The status of crural and foot arteries and the number of collaterals did not correlate well with early patency. Limbs with no patent crural artery that were analyzed in the poor angiographic runoff group, according to our previously reported classification, demonstrated relatively higher patency rates than the other subgroups with poor runoff. In cases where angiography demonstrates a poor runoff for distal revascularization, popliteal bypass with occluded crural arteries might achieve acceptable patency rates.

A simple infusion method for measurement of intraoperative peripheral vascular runoff resistance.

A simple infusion system to assess the status of distal runoff was investigated on both hindlimbs of five mongrel dogs. Infusion catheters were placed in the superficial femoral arteries and the origin of the lower leg arteries was exposed for anatomic manipulation of the distal runoff. Saline solution was infused through the superficial femoral arteries at 64, 129, and 193 cm levels to calculate volume flow and index of resistance to flow. The in vitro part of the study was undertaken to analyze the effect of different-size catheters on flow rates in a rigid undistensible model. In the hindlimb study the flow differed significantly between two- and one-vessel runoff status at 50 and 100 mm Hg infusion pressures. In the in vitro study, in contrast to the hindlimb study, index of resistance to flow values for different-size catheters remained almost unchanged as the infusion pressure increased, demonstrating the distensibility of the runoff bed in dogs. A preliminary clinical study in 13 patients undergoing infrainguinal bypass surgery demonstrated a good correlation between angiographic runoff evaluation and intraoperative flow values. Valuable information can be obtained about the status of the distal runoff by this simple infusion method, which might be used to improve the prediction of outcome of infrainguinal bypass surgery.

Natural history of patients with abdominal aortic aneurysm.

Factors determining the outcome for patients with abdominal aortic aneurysm (AAA) were analysed in a retrospective population-based study of 187 consecutively diagnosed AAAs at one hospital during a 9-year period. All aneurysms were diagnosed by ultrasound, and those cases that were not primarily operated upon, were followed by repeat ultrasound examinations. An expansion rate of more than 0.4 cm/year was seen in 27% of the aneurysms and a tendency towards a higher rate of expansion could be seen with larger lesions. The overall cumulative rupture rate was 12% at 5 years. For patients with small (less than 5 cm) aneurysms it was 2.5% at 7 years, and no aneurysm could definitively be shown to be smaller than 5 cm at the time of rupture. The rupture risk was significantly higher (28% at 3 years) for larger aneurysms (greater than or equal to 5 cm). The only reliable predictor for rupture was aneurysm size. The overall cumulative survival was 51% at 5 years. Patients with large aneurysms did not have a significantly shorter survival although a tendency for this to be the case was found. There was a significant difference between the proportion of deaths caused by aneurysm rupture in patients with small aneurysms when compared to those with large aneurysms, 5.5 and 53%, respectively. The expansion rate for AAA was highly individual and aneurysm diameter was the only recognisable predictor of rupture. The rupture rate for AAAs smaller than 5 cm was lower than previously reported.

Abdominal aortic aneurysm with perianeurysmal fibrosis: experience from 11 Swedish vascular centers.

Case records of 2026 patients operated on because of abdominal aortic aneurysms from 11 Swedish Vascular Centers were reviewed and revealed 98 cases (4.8%) of inflammatory abdominal aortic aneurysm. Also included in this case-control study was an analysis of a randomized group of 82 patients from the same centers who had noninflammatory abdominal aortic aneurysms. Four inflammatory aneurysms were ruptured, compared with 16 in the noninflammatory group (p less than 0.01). A higher proportion of patients with inflammatory abdominal aortic aneurysms had symptoms that led to radiographic investigations. The median erythrocyte sedimentation rate was 39 mm versus 19 mm (26% of patients with inflammatory abdominal aortic aneurysms had erythrocyte sedimentation rates greater than 50 mm; p less than 0.001), and the serum creatinine level was increased in 27 and 8 patients (p less than 0.01) in the inflammatory and noninflammatory groups, respectively. Preoperative investigations revealed ureteral obstruction in 19 patients with inflammatory abdominal aortic aneurysms, of whom 12 had preoperative nephrostomy or ureteral catheter placement. At operation, 20 additional patients exhibited fibrosis around one or both ureters. Although ureterolysis was performed in 19 patients, preoperative and postoperative creatinine levels did not differ between these patients and the conservatively treated ones. Duration of surgery (215 vs 218 minutes), intraoperative blood loss (2085 vs 2400 ml) and complications did not differ significantly between the groups. Overall operative (30-day) mortality was equal (11% vs 12%) but was increased for patients undergoing elective surgery for inflammatory abdominal aortic aneurysms (9% vs 0%; p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiographic criteria for prediction of early graft failure of secondary infrainguinal bypass surgery.

Complete intraoperative postreconstruction angiograms were obtained during 93 reoperations after failed femoropopliteal and femorodistal bypass grafts to evaluate the predictive value of a new method of angiographic runoff assessment. Good runoff was defined as patency of two or three lower leg arteries to the foot, or one patent vessel continuous with an intact anterior or posterior foot arch in femoropopliteal and proximal femorodistal bypasses, and integrity of both arches in low femorodistal bypasses. All other outflow patterns were considered poor. The cumulative 1-year patency rate was 61% with a 79% limb salvage rate after reoperations performed in limbs with good runoff. In reoperations with poor runoff, the patency rate was only 5% with a 22% limb salvage rate. In reoperations with good runoff, and 85% patency rate of vein grafts compared to 43% of prosthetic grafts clearly demonstrated the importance of graft material on early outcome. The improved prediction of early outcome with this new method of angiographic runoff evaluation might allow more rational management of patients with failed infrainguinal grafts.

A new method of angiographic runoff evaluation in femorodistal reconstructions. Significant correlation with early graft patency.

In 62 patients undergoing femorodistal bypass surgery, the foot vessel runoff was analyzed with a new grading system based on intraoperative postreconstruction serial angiography. The patients were divided into two groups according to the level of the distal anastomosis (proximal or low). Good runoff was defined as integrity of the anterior and/or posterior foot arch in proximal femorodistal grafts and integrity of both arches in low bypasses. In the proximal group, runoff was classified as poor when the arches were deficient or occluded, and in the low group, when only one arch was intact. The patency rate after 6 months was 81% in the good runoff group, whereas all grafts in patients with poor runoff were occluded. The new method allowed better prediction of the early outcome than does the primary and secondary pedal arch integrity concept.