Management and outcomes of axial isolated distal deep vein thrombosis at North Shore Hospital, New Zealand: a retrospective audit.

BACKGROUND: It is standard of care to treat proximal vein deep vein thrombosis (DVT) for a minimum of 3 months. Conversely, management of isolated distal DVT (IDDVT) is controversial, with options including observation and repeat ultrasound scan within 1 week to detect and anticoagulate those with proximal propagation, or anticoagulation for periods of up to 3 months. AIM: The aim was to assess the rates of proximal propagation and venous thromboembolism (VTE) recurrence within 3 months of diagnosis of IDDVT, and to examine how the duration of treatment might influence this. METHODS: Study patients were identified by retrospective audit of data from the North Shore Hospital VTE database. All patients presenting with established axial vein distal DVT from July 2007 to June 2012 were included. A 6-week treatment duration cut-off was used to separate the treatment arms (<6 weeks vs 6 weeks vs >6 weeks), and Fisher's exact or Pearson's Chi-squared tests were used to assess between-group comparisons. RESULTS: Five hundred and seven patients were included in the study, mean age 59.7 years; 53% female. There were three cases of proximal propagation, all occurring in those receiving <6 weeks treatment. There were six VTE recurrences, three in the <6 week and three in the ≥6 week treatment groups respectively. Malignancy was the only significant predictor of VTE recurrence (P = 0.001). CONCLUSION: A 6-week duration of anticoagulation appears to be an effective and safe treatment for isolated axial distal DVT, with low rates of VTE recurrence and proximal propagation.

Management and outcomes of single subsegmental pulmonary embolus: a retrospective audit at North Shore Hospital, New Zealand.

BACKGROUND: It is unknown whether filling defects in subsegmental arteries on multidetector computed tomography pulmonary angiography correlate with clinically relevant subsegmental pulmonary embolism (PE) on pulmonary angiography. Current guidelines do not differentiate between PE in segmental and subsegmental vessels, and many patients receive at least 3 months anticoagulation. The strategy employed at North Shore Hospital in haemodynamically stable patients with single subsegmental PE is to perform bilateral lower leg compression ultrasound (CUS). Anticoagulation is withheld if CUS is negative; a bilateral CUS is repeated in 7-10 days. AIM: The aim of this retrospective audit was to ensure our current management strategy is safe. METHODS: All diagnoses of single subsegmental PE between June 2005 and June 2013 were included. The primary outcome was the rate of venous thromboembolism (VTE) recurrence within 3 months of single subsegmental PE diagnosis. Secondary outcomes were rates of major/minor bleeding and all-cause mortality. RESULTS: Thirty-two patients were included - 20 were treated with anticoagulation; 12 were managed with observation/serial bilateral lower limb CUS. None of the patients in either group had VTE recurrence by 3 months. No bleeding episodes were observed in the observation group; there was a 10% major bleeding rate (n = 2) in the treatment group. One death occurred in each group, neither of which was attributed to VTE. CONCLUSION: Withholding anticoagulation in patients with single subsegmental PE and negative serial bilateral CUS appears to be a safe and effective management strategy, with a low risk of VTE recurrence.

Incidence of venous thromboembolism in different ethnic groups: a regional direct comparison study.

BACKGROUND: There are few studies that directly compare the variation in incidence of venous thromboembolism (VTE) according to ethnicity. OBJECTIVE: The aim of this study was to compare the rates of VTE, deep venous thrombosis (DVT) and pulmonary embolism (PE) among different ethnic groups. METHOD: The cases diagnosed with VTE, DVT and PE for a period between March 2004 and June 2009 were identified through the hospital-based database system. The 2006 New Zealand Census data were used to calculate the rate of diagnosis. RESULTS: The observed annual incidence of VTE during this period was 81.6 per 100000 population. The relative risks of VTE when comparing European subjects with Maori, Pacific Island and Asian subjects after age standardization were 1.98 (95% confidence interval [CI], 1.63-2.41), 3.22 (95% CI, 2.60-3.99) and 4.02 (95% CI, 3.34-4.84), respectively. Relative risks of DVT after age standardization when comparing European subjects with Maori, Pacific Island and Asian subjects, were 2.14 (95% CI, 1.72-2.66), 3.20 (95% CI, 2.46-4.17) and 4.75 (95% CI, 3.80-5.94), respectively. Indirect age standardization was used for comparison of the diagnosis of PE. The ratio between the calculated expected number of cases and the actual number of cases was 1.32 (95% CI, 0.89-1.75) for Maori subjects, 2.96 (95% CI, 1.89-4.03) for Pacific Islanders and 3.89 (95% CI, 3.00-4.78) for Asians. CONCLUSION: Europeans have a significantly higher incidence of VTE compared with Maori, Pacific Island and Asian populations.

How do we manage venous thromboembolism in pregnancy? A retrospective review of the practice of diagnosing and managing pregnancy-related venous thromboembolism at two major hospitals in Australia and New Zealand.

BACKGROUND: North American and European literature suggest that the incidence rate for pregnancy-related thromboembolism (VTE) ranges from 0.5 to 2 per 1000 pregnancies. However, there is a paucity of data regarding pregnancy-related VTE in Australia and New Zealand. AIMS: To define the epidemiology, management and adverse effects of pregnancy-related VTE in Australia and New Zealand. METHOD: Retrospective chart review of pregnant patients with objectively diagnosed pregnancy-related VTE at Monash Medical Centre and the North Shore Hospital from January 2007 to March 2011. RESULTS: Sixty women with VTE were identified, 31 and 29 in the antepartum and post-partum period respectively. VTE occurred as early as 8 weeks of gestation. There was a trend towards higher proportion of PE in the postpartum period. Most antenatal patients were started on enoxaparin and dosed according to weight at diagnosis. A wide variability in maintenance dosing strategies was observed. Three (5%, 95% CI: 1% to 14%) patients suffered major bleeds, all occurring post-partum. Recurrences occurred in two post-partum patients who received a truncated course of enoxaparin for distal deep-vein thrombosis. Although more women had an induction of labour, this did not translate into an increased Caesarean section rate. CONCLUSION: The epidemiology of pregnancy-related VTE is similar to that of other developed countries. All three bleeding events occurred in the immediate post-partum setting, highlighting the need for caution at this critical time. VTE recurrences occurred in those women with post-partum distal deep-vein thrombosis treated with an abbreviated course of enoxaparin.

A simplified approach to estimating the maximal lactate steady state.

The exercise intensity associated with an elevated but stable blood lactate (HLa) concentration during constant load work (the maximal steady state, MSS) has received attention as a candidate for the "optimal" exercise intensity for endurance training. Identification of MSS ordinarily demands direct measurement of HLa or respiratory metabolism. The purpose of this study was to test the ability of heart rate (HR) to identify MSS during steady state exercise, similar to that used in conventional exercise prescription. Trained runners (n = 9) and cyclists (n = 12) performed incremental and steady state exercise. MSS was defined as the highest intensity in which blood lactate concentration increased < 1.0 mM from minutes 10 to 30. The next higher intensity workbout completed was defined as > MSS. HR models related to the presence or absence of steady state conditions were developed from the upper 95% confidence interval of MSS and the lower 95% confidence interval of > MSS. Cross validation of the model to predict MSS was performed using 21 running and 45 cycling exercise bouts in a separate group. Using the MSS upper 95% confidence interval model 84% and 76% of workbouts were correctly predicted in cyclists and runners, respectively. Using the > MSS lower 95% confidence interval model, 76% and 81% of workbouts were correctly predicted in cyclists and runners, respectively. Prediction errors tended to incorrectly predict non-steady state conditions when steady state had occurred (16/26) (62%). We conclude that use of these simple HR models may predict MSS with sufficient accuracy to be useful when direct HLa measurement is not available.

Plasma free and sulfoconjugated catecholamines during sustained exercise.

Previous research established a relationship between circulating sulfoconjugated norepinephrine (NE-SO4) and oxygen consumption at various exercise intensities. In this study, the stability of the NE-SO4 response was examined during sustained exercise at a constant relative intensity. Seven trained men bicycled at 78 +/- 3% of their maximal O2 consumption for 28 min and then rested on the ergometer for a comparable duration. After a 30-min rest, plasma samples were collected through an indwelling catheter at 7-min intervals during the exercise and recovery periods. Free NE and epinephrine increased sixfold during exercise. These changes were accompanied by increases in sulfoconjugated catecholamines, but only NE-SO4 achieved statistical significance (rest, 712 +/- 602; exercise, 1,329 +/- 1,163 pg/ml). This occurred at three collection periods (14, 21, and 28 min). Approximately 35, 52, and 95% of NE, epinephrine, and dopamine, respectively, existed as sulfoconjugated during exercise. Subject variation was present in the sulfoconjugated catecholamine response that could not be attributed to corresponding differences in circulating free catecholamine release. These findings implicate blood flow as a factor in the sulfoconjugation of NE, but not epinephrine or dopamine.