Evaluation of the use of low-molecular-weight heparin for venous thromboembolism prophylaxis in medical patients

Background. Venous thromboembolism (VTE) complicates a significant proportion of medical admissions. As well as increasing patient morbidity, pulmonary embolism is one of the commonest preventable causes of in-hospital death. An increase in the use of pharmacological preventive measures has been advocated in recent years. South African (SA) and international guidelines have been published in an effort to promote the safe use of VTE prophylaxis.Objectives. To describe adherence to both local and international recommendations for VTE prophylaxis in an SA hospital with regard to appropriateness of the decision to prescribe or withhold low-molecular-weight heparin (LMWH), and to observe the practice of dose adjustment in special population groups.Methods. This was a prospective, observational study, and data were collected from consenting adults admitted to the medical wards. We assessed the patients’ VTE risk, bleeding risk and the presence of contraindications at the time of LMWH prescription as well as the dose prescribed, specifically taking into consideration adjustment for renal dysfunction and obesity.Results. Three hundred and fifty-two patients were enrolled, of whom 51.4% were male and 58.5% received LMWH. Primary outcomes. The appropriate overall decision according to both SA and international guidelines was made in 254 cases (72.2%). The inappropriate decision according to both guidelines was made in 79 cases (22.4%) and the appropriate decision according to one guideline only was made in 18 cases (5.1%), while 1 case (0.3%) was not categorised. Contraindications to VTE prophylaxis were present in 35 patients (9.9%), but 9 of these patients nevertheless received LMWH. An incorrect dose was prescribed in 36 cases (17.5%), the most common reason being an inappropriate reduction in the dose in mild renal dysfunction. Secondary outcomes. Other medications that may have increased bleeding risk were prescribed in 46 patients who received LMWH (22.3%). Mechanical prophylaxis was indicated in 25 (7.1%) of the total sample; however, none received this.Conclusions. Overall adherence to published guidelines for VTE prophylaxis has improved compared with other published reviews on the topic, but documentation of patients’ VTE risk in files is poor. Overuse in low-risk patients may be an unintended consequence of the widespread advocacy of LMWH use in hospital, highlighting the importance of adequate VTE risk stratification. Incorrect dosing in special population groups is an issue that needs to be addressed, as is non-utilisation of mechanical prophylaxis methods.

Time to thrombolysis and factors contributing to delays in patients presenting with ST-elevation myocardial infarction at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa

Background. Acute coronary syndrome is a public health burden both worldwide and in South Africa (SA). Guidelines recommend thrombolysis within 1 hour of symptom onset and 30 minutes of hospital arrival for patients with ST-elevation myocardial infarction (STEMI) in order to prevent morbidity and mortality. There is a paucity of data pertaining to the time between onset of chest pain and thrombolysis in STEMI patients in SA. Objectives. To elucidate the time to thrombolytic therapy, establish the reasons for treatment delays, and calculate the loss of benefit of thrombolysis associated with delays in treatment of patients presenting with STEMI at Chris Hani Baragwanath Academic Hospital (CHBAH), Johannesburg, SA. Method. A prospective observational study of 100 consecutive patients with STEMI was conducted at CHBAH (2021 - 2022). Results. The mean (standard deviation) age was 55.6 (11.6) years, with a male predominance (78%). Thrombolytic therapy was administered to 51 patients, with a median (interquartile range (IQR)) time to thrombolysis of 360 (258 - 768) minutes; 10 of the patients who received a thrombolytic (19.6%) did so within 30 minutes of arrival at the hospital. The median (IQR) time from symptom onset to calling for help was 60 (30 - 240) minutes, the median time from arrival of help to hospital arrival was 114 (48 - 468) minutes, and the median in-hospital delay to thrombolysis after arrival was 105 (45 - 240) minutes. Numerous reasons that led to delay in treatment were identified, but the most frequent was prehospital delays related to patient factors. Late presentation resulted in 26/49 patients (53.1%) not receiving thrombolytic therapy. Five patients died and 43 suffered from heart failure. Thirty per 1 000 participants could have been saved had they received thrombolytic therapy within 1 hour from the onset of chest pain. Conclusion. Prehospital and hospital-related factors played a significant role in delays to thrombolysis that led to increased morbidity and mortality of patients with STEMI

Pattern, Process, and Natural Disturbance in Vegetation

Natural disturbances have been traditionally defined in terms of major catastrophic events originating in the physical environment and, hence, have been regarded as exogenous agents of vegetation change. Problems with this view are: (1) there is a gradient from minor to major events rather than a uniquely definable set of major catastrophes for each kind of disturbance, and (2) some disturbances are initiated or promoted by the biotic component of the system. Floras are rich in disturbance-adapted species. Disturbances have probably exerted selective pressure in the evolution of species strategies. Heathland cyclic successions and gap-phase dynamics in forests have been viewed as endogenous patterns in vegetation. When death in older individuals imposes a rhythm on community reproduction, dynamics may indeed be the result of endogenous factors. However, documented cases of senescence in perennial plants are few and many cyclic successions and cases of gap-phase dynamics are initiated by physical factors. Forest dynamics range from those that are the result of individual tree senescence and fall, through those that are the result of blowdown of small groups of healthy trees, to those that are the result of large wind- storms which level hectares of forest. The effect of wind ranges from simple pruning of dead plant parts to widespread damage of living trees. Wind speed is probably inversely proportional to occurrence frequency. Disturbances vary continuously. There is a gradient from those community dynamics that are initiated by endogenous factors to those initiated by exogenous factors. Evolution has mediated between species and environment; disturbances are often caused by physical factors but the occurrence and outplay of disturbances may be a function of the state of the community as well