Propagation of a spherical shock in an inhomogeneous self-gravitating or nongravitating system

The propagation of a shock wave of finite strength due to an explosion into inhomogeneous nongravitating and self-gravitating systems has been considered, using similarity principles, supposing that the density varies as an inverse power of distance from the centre of explosion. A large number of systems, characterised by different density exponents and different adiabatic coefficients of the gas have been considered for different shock strengths. The numerical integration from the shock inward has been continued to the surface of singularity where density tends to infinity and which acts like a piston in the self-gravitating case and to the surface where the velocity gradient tends to infinity in the nongravitating case. The effect of variation of shock strength, density exponent and adiabatic coefficient on the location of these singularities and on the distribution of flow parameters behind the shock has been studied. The initial energy of the system and the manner of release of the explosion energy influence strongly the flow behind the shock. The results have been graphically depicted

Propagation of a spherical shock in an inhomogeneous self-gravitating or nongravitating system

The propagation of a shock wave of finite strength due to an explosion into inhomogeneous nongravitating and self-gravitating systems has been considered, using similarity principles, supposing that the density varies as an inverse power of distance from the centre of explosion. A large number of systems, characterised by different density exponents and different adiabatic coefficients of the gas have been considered for different shock strengths. The numerical integration from the shock inward has been continued to the surface of singularity where density tends to infinity and which acts like a piston in the self-gravitating case and to the surface where the velocity gradient tends to infinity in the nongravitating case. The effect of variation of shock strength, density exponent and adiabatic coefficient on the location of these singularities and on the distribution of flow parameters behind the shock has been studied. The initial energy of the system and the manner of release of the explosion energy influence strongly the flow behind the shock. The results have been graphically depicted

Hot climate and perioperative outcome in elderly patients

Background: It is well known that heat wave is a major cause of weather related mortality in extreme of ages. While auditing our hospital mortality record, we found higher surgical mortality in the months of summer season which inspired us to look into the impact of hot climate in elderly surgical patients. Materials and Methods: An observational prospective cohort study was undertaken to study the impact of hot climate on elderly (age > 60 yrs) surgical patients over one year when outside temperature was more than 20 o C. 98 elderly patients requiring general anaesthesia for surgery were enrolled. Patients were grouped on the basis of peak outdoor temperature with a cut off value of 30 o C. Group I- when peak outdoor temperature ranged between 20-30 o C (comfortable zone) and Group II - when peak outdoor temperature ranged above 30 o C. To reduce the bias, inclusion and exclusion criterion were defined. Meteorological factors, patient characteristics, surgical risk factors and other related data were noted. Data was analyzed using student\u2032s\u2032t\u2032 and z-test for statistical significance. Results: There were statistically significant complications and prolonged hospital stay in group II as compared to I (13.21\ub16.44 Vs 9.81\ub13.54 days, P value =0.01) on univariate analysis. High risk patients had more complications in hot weather. Stepwise multivariate regression analysis showed higher adverse impact of poor physical and cardiac status than hot climate. Conclusion: Hot and humid weather adversely affect the perioperative outcome in elderly surgical patients. Patients with poor reserves are at greater perioperative risk during hot and humid climate

Hot climate and perioperative outcome in elderly patients

Background: It is well known that heat wave is a major cause of weather related mortality in extreme of ages. While auditing our hospital mortality record, we found higher surgical mortality in the months of summer season which inspired us to look into the impact of hot climate in elderly surgical patients. Materials and Methods: An observational prospective cohort study was undertaken to study the impact of hot climate on elderly (age > 60 yrs) surgical patients over one year when outside temperature was more than 20 o C. 98 elderly patients requiring general anaesthesia for surgery were enrolled. Patients were grouped on the basis of peak outdoor temperature with a cut off value of 30 o C. Group I- when peak outdoor temperature ranged between 20-30 o C (comfortable zone) and Group II - when peak outdoor temperature ranged above 30 o C. To reduce the bias, inclusion and exclusion criterion were defined. Meteorological factors, patient characteristics, surgical risk factors and other related data were noted. Data was analyzed using student′s′t′ and z-test for statistical significance. Results: There were statistically significant complications and prolonged hospital stay in group II as compared to I (13.21±6.44 Vs 9.81±3.54 days, P value =0.01) on univariate analysis. High risk patients had more complications in hot weather. Stepwise multivariate regression analysis showed higher adverse impact of poor physical and cardiac status than hot climate. Conclusion: Hot and humid weather adversely affect the perioperative outcome in elderly surgical patients. Patients with poor reserves are at greater perioperative risk during hot and humid climate

Non-surgical pneumoperitoneum and pneumoretroperitoneum associated with mechanical ventilation

We present two rare cases of mechanical ventilation-associated barotrauma presenting with pneumoperitoneum and pneumoretroperitoneum separately. Pneumoperitoneum and pneumoretroperitoneum are not always associated with a hollow viscous perforation and can be seen due to barotrauma as a consequence of the Macklin effect

Effect of tranexamic acid on blood loss and transfusion requirement in total knee replacement in the Indian population: A case series

Context: Total knee replacement (TKR) is often carried out using a tourniquet to minimize intraoperative blood loss. However, its application enhances local fibrinolysis, resulting in excessive blood loss during the post-operative period. Fibrinolytic profile varies in different regions and races. Tranexamic acid has been shown to reduce post-operative blood loss and the need for transfusion in TKR. However, there is paucity of literature from the Indian population and the efficacy of the agent has not been tested in Indian patients undergoing TKR. Aims: Effect of tranexamic acid on blood loss in TKR surgery in the Indian population. Setting and Design: In this double-blinded study, 40 patients undergoing unilateral TKR were randomly divided into two groups. Methods: All patients were conducted under spinal anaesthesia using injection bupivacaine 0.5% heavy 12-15 mg. The treatment group received 10 mg/kg tranexamic acid, intravenous (IV), half an hour before deflation of the tourniquet, with a second dose of 2 mg/kg administered 3 hours after the first dose. The exact protocol was followed for the placebo group, except that normal saline was used instead of tranexamic acid. Blood loss, blood transfusion details and change in haemoglobin levels were noted. Statistical Analysis: Student′s paired ′t′ test was used in statistical analysis. Results: The mean post-operative blood loss in the tranexamic acid group was 272.5±122.5 ml (mean±SD), and 685±118.2 ml in the placebo group (P<0.001). The total blood loss was lower in the tranexamic acid group than in the placebo group (427.6 ml vs. 911.6 ml; P<0.001). The absolute number of blood transfusions and the number of patients who required transfusions were lower in the tranexamic acid group than in the placebo group. None of the patients had any side or adverse effect. Conclusions: Tranexamic acid significantly decreases post-operative blood loss and reduces the need for blood transfusion in patients undergoing TKR

Isquemia miocárdica silenciosa em pacientes submetidos à prostatectomia transuretral: comparação entre anestesia subaracnóidea e peridural Isquemia miocárdica silenciosa en pacientes sometidos a prostatectomia transuretral: comparación entre anestesia subaracnóidea y peridural Silent myocardial ischaemia in patients undergoing transurethral resection of prostate: comparison of spinal versus epidural anaesthesia

JUSTIFICATIVA E OBJETIVOS: A isquemia miocárdica silenciosa foi recentemente relacionada ao aumento de morbimortalidade cardíaca peri-operatória. Até 41% dos pacientes com doença coronariana conhecida ou fatores de risco cardíaco, submetidos à cirurgias não cardíacas, apresentaram isquemia peri-operatória. Vários autores compararam técnicas de anestesia regional e geral mas nenhum comparou o impacto de diferentes técnicas de anestesia no neuro-eixo na incidência e duração da isquemia miocárdica silenciosa. O objetivo deste estudo foi comparar duas técnicas diferentes de anestesia no neuro-eixo (subaracnóidea versus peridural) em pacientes idosos aleatoriamente selecionados e submetidos à prostatectomia transuretral. Optou-se por este grupo de pacientes idosos porque freqüentemente, apresentam doença coronariana silenciosa ou clinicamente aparente. Um outro fator importante que influenciou a escolha, foi a sobrecarga de volume e tremores causados pela prostatectomia transuretral nesses pacientes promovendo desequilíbrio entre consumo e oferta de oxigênio. MÉTODO: Participaram deste estudo 40 pacientes submetidos a prostatectomia transuretral, que foram estudados em relação à isquemia miocárdica silenciosa com a ajuda de um equipamento Holter. A monitorização iniciou-se 1 hora antes da cirurgia, prosseguiu durante a cirurgia e após pelas próximas 24 horas. Os dados do Holter foram analisados por um DSM modelo 300. RESULTADOS: A incidência geral de isquemia miocárdica silenciosa neste estudo foi de 30%. Não foi estabelecida nenhuma relação entre isquemia miocárdica silenciosa e o tipo de anestesia. A maior parte dos episódios de isquemia miocárdica ocorreu no período pré-operatório e não tiveram relação com alterações hemodinâmicas. No entanto, a incidência e a gravidade de isquemia miocárdica silenciosa foi mais alta em pacientes com altos escores de Detsky, hipertensão arterial e anemia. Nenhum paciente apresentou efeitos cardíacos adversos. CONCLUSÕES: O tipo de anestesia no neuro-eixo não influenciou a incidência de isquemia miocárdica silenciosa.JUSTIFICATIVA Y OBJETIVOS: La isquemia miocárdica silenciosa fue recientemente relacionada al aumento de morbi-mortalidad cardíaca peri-operatoria. Hasta 41% de los pacientes con enfermedad coronariana conocida o con factores de riesgo cardíaco, sometidos a cirurgías no cardíacas, presentan isquemia peri-operatoria. Varios autores compararon las técnicas de anestesia regional y general, más ninguno comparó el impacto de diferentes técnicas de anestesia del neuro-eixo en la incidencia y duración de la isquemia miocárdica silenciosa. El objetivo de este estudio fue la de comparar dos técnicas diferentes de anestesia en el neuro-eixo (subaracnóideo versus. peridural) en pacientes edosos aleatoriamente seleccionados y sometidos a prostatectomia transuretral. Optaou-se por pacientes idosos por frecuentemente presenta enfermedad coronariana silenciosa o aparente. Outro factor importante que influenció la escoja, fue la sobrecarga de volumen y tremores causados por prostatectomia transuretral en esos pacientes promovendo desequilibrio entre el consumo y oferta de oxígeno. MÉTODO: Participaron de este estudio 40 pacientes sometidos a prostatectomia, fueron estudiados en relación a la isquemia miocárdica silenciosa con la ayuda de un equipamiento Holter. La monitorización se inició 1 hora antes de la cirugía y prosiguió durante la misma y después por las próximas 24 horas. Los datos del Holter fueron analizados por un DSM modelo 300. RESULTADOS: La incidencia general de isquemia miocárdica silenciosa en este estudio fue de 30%. No fue establecida ninguna relación entre isquemia miocárdica silenciosa y tipo de anestesia. La mayor parte de los episodios de isquemia miocárdica ocurrió en el período pre-operatorio y no tuvieron relación con alteraciones hemodinámicas. No obstante, la incidencia y la gravidad de isquemia miocárdica silenciosa fue más alta en pacientes con altos contajes de Detsky, hipertensión arterial y anemia. Ningún paciente presentó efectos cardíacos adversos. CONCLUSIONES: El tipo de anestesia no influenció la incidencia de isquemia miocárdica silenciosa.BACKGROUND AND OBJECTIVES: In the recent past, silent myocardial ischaemia has been found to be associated with increased perioperative cardiac morbidity and mortality. As many as 41 % of patients with either known coronary artery disease or with cardiac risk factors, undergoing a non-cardiac surgery, develop perioperative ischaemia. Various authors have compared regional techniques with general Anaesthesia in selected groups but no one has compared the impact of different techniques of centroneuraxial block on incidence and duration of silent myocardial ischaemia. Thus we compared two different techniques of centroneuraxial block (Spinal versus Epidural block) in aged patients selected randomly undergoing TURP surgery. We took TURP patients as they belong to geriatric age group and often have silent or apparent coexistent coronary artery disease. Secondly, TURP surgery related volume overload and shivering in these patients lead to further oxygen demand supply mismatch. METHODS: Forty patients undergoing transurethral resection of prostate were monitored for perioperative silent myocardial ischaemia with the aid of a Holder device. Holter monitoring was started 1 hour prior to surgery and then continued during and after surgery the for next 24 hours. Holter data was analyzed using DSM model 300. RESULTS: The overall incidence of silent myocardial ischaemia in our study was 30%. No relationship could be established between silent myocardial ischaemia and type of centroneuraxial block. Most of the episodes of myocardial ischaemia occurred in preoperative period and, these had no correlation with hemodynamic fluctuations. However the incidence and load of silent myocardial ischaemia was higher in-patients with high Detsky scoring, hypertension and anaemia. None of the patient had any adverse cardiac outcome. CONCLUSIONS: Type of centroneuraxial block has no effect on incidence of silent myocardial ischaemia