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Biomedical subjects

A S Tomar

Publications and source records attributed to A S Tomar.

18 recordsLinked to original sources
PubMed2006

Length of insertion for pulmonary artery catheters to locate different cardiac chambers in patients undergoing cardiac surgery.

BACKGROUND: Although, guidelines related to length of insertion of a pulmonary artery catheter to reach a particular cardiac chamber are available, these are not backed by clinical studies. We measured the length of insertion of pulmonary artery catheters to locate the right ventricle, pulmonary artery and pulmonary capillary wedge positions in 300 adult patients undergoing elective cardiac surgery. METHODS: The pulmonary artery catheters were inserted using a standard technique through the right internal jugular vein. The right ventricle, pulmonary artery and wedge position of the catheter were confirmed by the characteristic waveforms, and the length of insertion to these points was measured. RESULTS: The right ventricle was reached at 24.6 (3) cm (95% CI 24.2-24.9 cm), pulmonary artery at 36 (4) cm (95% CI 35.6-36.5 cm) and wedge position at 42.8 (5.7) cm (95% CI 42.2-43.5 cm). The length of catheter to reach the right ventricle, pulmonary artery and wedge position was significantly more in patients undergoing valve surgery as compared with those undergoing coronary artery bypass grafting [26 (3.8) and 24 (2.5) cm; 38.5 (4.6) and 35 (3.2) cm; and 47.8 (6.9) and 41.2 (4.1) cm, respectively, P<0.001]. The length of insertion to reach pulmonary artery and pulmonary capillary wedge position was directly related to height of the patient (Pearson's correlation 0.157 and 0.15, respectively). CONCLUSIONS: We have provided the norms related to length of insertion of pulmonary artery catheter, which should be useful in accurate placement of the catheter and minimize complications related to coiling of the catheter.

Adolescent↗
PubMed2001

Comparison of the effects of a cell saver and low-dose aprotinin on blood loss and homologous blood usage in patients undergoing valve surgery.

OBJECTIVE: To compare 2 important techniques of blood conservation, use of a cell saver and low-dose aprotinin, in terms of blood loss and homologous blood usage in patients undergoing cardiac valve surgery. DESIGN: Prospective, randomized. SETTING: Tertiary care hospital. PARTICIPANTS: Sixty adult patients undergoing elective valve surgery. INTERVENTIONS: The patients were divided into 3 groups of 20 each. In group 1, aprotinin in the dose of 30,000 KIU/kg was added to the pump prime, with a further dose of 15,000 KIU/kg added at the end of each hour of cardiopulmonary bypass. In group 2, a cell-saver system was used to collect all blood at the operation site for processing in preparation for subsequent reinfusion. Group 3 patients acted as a control group and underwent routine management, which included collection of autologous blood during the pre-cardiopulmonary bypass period. A hemoglobin of <8 g/dL was considered as an indication for bank blood transfusion in the postoperative period. MEASUREMENTS AND MAIN RESULTS: The chest tube drainage was significantly less in group 1 compared with groups 2 and 3, with total drainage (median [interquartile range]) amounting to 250 mL [105 to 325 mL] vs. 700 mL [525 to 910 mL] in group 2 and 800 mL [650 to 880 mL] in group 3 (p < 0.001). The patients in groups 1 and 2 required significantly less bank blood (median [interquartile range]) as compared with group 3 (350 mL [0 to 525 mL], 350 mL [0 to 350 mL], and 1050 mL [875 to 1050 mL]; p < 0.001), respectively. Cell saver provided 410 +/- 130 mL of hemoconcentrated blood in group 2. The average preoperative hemoglobin concentration was 11.3 g/dL, and it was around 9 g/dL on the 7th postoperative day. The hemoglobin concentration at various stages during hospitalization in all 3 groups was similar. CONCLUSIONS: Low-dose aprotinin and a cell saver are effective and comparable methods of blood conservation. Aprotinin helps by decreasing the postoperative drainage, and a cell saver helps by making the patient's own blood available for transfusion.

Adult↗
PubMed1996

Balloon mitral commissurotomy: an intraoperative assessment.

OBJECTIVE: Advances in balloon catheter technology have revolutionized the management of obstructive cardiovascular diseases. For lesions like mitral stenosis, balloon commissurotomy has emerged as an alternative to surgical relief showing definite functional benefits in a few clinical trials, albeit with variable results. Such variability necessitated objective evaluation of the efficacy of balloon mitral commissurotomy. METHODS: The balloon mitral commissurotomy was carried out in 11 patients suffering from isolated mitral stenosis, under vision in a surgical setting. All patients were in NYHA class III/IV. Initially single balloon was used for mitral commissurotomy followed by double balloon, before completing the mitral valvotomy with surgical instruments whenever required. The commissural split was measured by firmly stretching the two commissures using nerve hooks and measuring the distance between the two hooks with the help of a caliper. Assessment of balloon dilation was made by calculating exact percentage of residual commissural split following balloon dilation as compared with completed mitral valvotomy. The exact percentage of commissural split was thus obtained by subtracting residual commissural split following balloon dilation from commissural split obtained after surgical open mitral valvotomy. RESULTS: Complete commissurotomy using the balloon technique was possible in two (18.2%) patients. In the remaining nine (81.8%) patients, balloon expansion provided only 50% to 80% of commissural split and required instrumental completion with good results. CONCLUSIONS: Balloon mitral commissurotomy, by virtue of its circumferential force, helps to develop a good cleavage and attains good hemodynamic improvement which may be life saving in critical mitral stenosis in selected group of patients with pliable mitral leaflets and minimal subvalvular pathology.

Adolescent↗
PubMed1996

Blood conservation in small adults undergoing valve surgery.

OBJECTIVES: A substantial reduction in transfusion requirements for cardiac surgical procedures has been reported. Many of these reports have been described in patients undergoing coronary artery bypass grafting. Patients suffering from rheumatic heart disease in India are usually small and also anemic. This study was conducted to assess blood conservation methods for cardiac valve surgery in this subset of patients. DESIGN: This was a prospective, randomized study. SETTING: The study was performed in a New Delhi tertiary care hospital, and the patients were referred from the northern states of India. PARTICIPANTS: One hundred fifty consecutive patients undergoing elective valve surgery using cardiopulmonary bypass were included. The mean age was 27.7 years and mean weight was 45.2 kg. INTERVENTIONS: The patients were divided into three groups of 50 each. Group 1 received autologous fresh blood donated before bypass, and both a cell saver and membrane oxygenator were used. The oxygenator contents at the end of perfusion were processed by cell saver. Group 2 patients were reinfused with autologous blood only, and group 3 was a control group. In groups 2 and 3, the blood that remained in the oxygenator at the conclusion of cardiopulmonary bypass was reinfused. A hematocrit of less than 25% was considered an indication for transfusion in the postoperative period. MEASUREMENTS AND MAIN RESULTS: The mean preoperative hematocrit was 35.5%. A mean of 361.1 mL of autologous blood was collected from group 1 and 303.3 mL from group 2. Group 1 required 15 units of bank blood, group 2, 90 units (p < 0.001), and group 3, 102 units (p < 0.001). Seventy-eight percent of group 1 patients did not receive any donor blood. There was no significant difference in chest tube drainage among the three groups. CONCLUSIONS: In this unique group of patients whose mean body weight was only 45 kg, autologous blood alone did not decrease blood bank requirements but when combined with a cell saver and membrane oxygenator greatly reduced the need for donor blood.

Adult↗
PubMed1995

Closed mitral valvotomy and elective ventilation in the postoperative period: effect of mild hypercarbia on right ventricular function.

OBJECTIVES: It is customary to extubate patients immediately after closed mitral valvotomy. These patients often have deranged respiratory function caused by chronic lung congestion. The left ventricular function may also be subnormal after valvotomy in some patients. Therefore, elective ventilation for some duration in the postoperative period can be beneficial to these patients. This work is an attempt to find whether elective ventilation should be preferred over immediate extubation in these patients. DESIGN: A prospective randomized study. SETTING: The study was performed in a tertiary care hospital, and the patients are referred from the northern states of India. PARTICIPANTS: One hundred patients undergoing elective closed mitral valvotomy were included in the initial part of the study. Ten more patients were studied to evaluate the effect of mild hypercarbia on right ventricular function after closed mitral valvotomy. INTERVENTIONS: One hundred patients were divided into two groups of 50 each. Group 1 consisted of patients in whom the neuromuscular blockade was reversed at the end of surgery with neostigmine and atropine and the trachea was extubated. In group 2, the residual neuromuscular paralysis was not reversed and the patients were electively ventilated in the postoperative period for an average duration of 5 hours and 29 minutes +/- 1 hour and 58 minutes. In all the patients in both the groups, electrocardiogram, direct arterial blood pressure, and oxygen saturation were continuously monitored, and arterial blood gases were measured intermittently throughout the study period. Because the results showed that there was mild hypercarbia, 30 minutes after extubation in group 1, 10 more patients were studied to evaluate the effect of mild hypercarbia on right ventricular function after surgery. Patients were ventilated after surgery (F1O2 = 1) to maintain normocarbia (PaCO238.6 +/- 3.4 mmHg). Mild hypercarbia PaCO251.5 +/- 3.7 mmHg) followed by normocarbia (PaCO2 40 +/- 2.5 mmHg) was induced by adjusting the ventilator rate with a constant tidal volume. Standard hemodynamic measurements were performed at each stage. MEASUREMENTS AND MAIN RESULTS: Although all the patients maintained satisfactory and stable hemodynamics in the postoperative period, the PaCO2 at the end of 30 minutes of extubation was significantly higher in group 1 (48.1 +/- 5.3 mmHg) as compared with group 2 (40.2 +/- 4.3 mmHg, p < 0.001). Mild hypercarbia significantly increased pulmonary vascular resistance (p < 0.01), mean pulmonary arterial pressure (p < 0.001), right ventricular stroke work (p < 0.01), right ventricular systolic pressure (p < 0.01), and right ventricular end-diastolic pressure (p < 0.001). The effect was not totally reversible with CO2 washout as all parameters except right ventricular end-diastolic pressure and pulmonary vascular resistance continued to remain significantly higher when normocarbia was restored. The significant changes in systemic hemodynamics produced by hypercarbia were increases in cardiac index, mean arterial pressure, and pulmonary capillary wedge pressure. CONCLUSIONS: Avoidance of even mild hypercarbia, therefore, appears advisable in the early postoperative period because of potential impedence to right ventricular ejection. Continuous monitoring of end-tidal CO2 and frequent blood gas analyses should be practiced, and elective ventilation should be considered in patients with long-standing disease and pulmonary hypertension.

Adolescent↗
PubMed1994

Myocardial depressant effect of nitrous oxide after valve surgery.

We have studied the cardiovascular effects of 50% nitrous oxide after cardiopulmonary bypass in 14 patients undergoing valve surgery. All patients received morphine as the principal anaesthetic. Nitrous oxide administration for 5 min caused a decrease in mean arterial pressure from 82 +/- 10 to 71 +/- 12.7 mmHg (P < 0.001), cardiac index (2.8 +/- 0.5 to 2.4 +/- 0.5 litres min-1 m-2, P < 0.01), heart rate (104 +/- 17 to 99 +/- 18 beats min-1, P < 0.05), left ventricular stroke work index (29.4 +/- 8.1 to 22 +/- 8.7 gm-m beat-1 mm-1, P < 0.001), stroke volume (45.3 +/- 11.6 to 40 +/- 12.8 ml beat-1, P < 0.05) and an increase in pulmonary vascular resistance from 106.4 +/- 53.9 to 143.9 +/- 81.0 dynes s cm-5 (P < 0.01) and right atrial pressure (1.42 +/- 2.09 to 1.71 +/- 2.21 mmHg, P < 0.05). There was no change in systemic vascular resistance. When nitrous oxide was discontinued all the parameters started to recover within 3 min. Mean arterial pressure returned to control value in 5 min, but cardiac index and pulmonary vascular resistance returned to control value in 10 min. Our results suggest a direct myocardial depression and that the use of nitrous oxide is not recommended immediately after valve surgery and cardiopulmonary bypass.

Adult↗
PubMedDate not supplied

Haemodynamic effects of leg raising in patients undergoing coronary artery bypass grafting.

Twenty patients undergoing elective coronary artery bypass grafting were studied prospectively to evaluate the haemodynamic effects of passive leg raising. The patients were divided into two groups: those having good left ventricular function with ejection fraction of 0.50 or more (group I, n = 10) and those having poor left ventricular function with ejection fraction of upto 0.35 (group II, n = 10). Morphine-based anaesthetic technique was used and standard haemodynamic measurements were obtained at following stages: (1) control--20 to 30 min after induction of anaesthesia; (2) one minute, and (3) five min after raising both the legs; (4) one min, and (5) five min after the legs were repositioned. In group I, heart rate decreased from 71 +/- 9 to 66 +/- 8 beats/min (p < 0.001) at stage 1 and persisted throughout the study period. This was accompanied by a decrease in cardiac index, although, the statistical significance was achieved at stage 3 and 4 only. The haemodynamic changes observed in group II were of more severe magnitude. The heart rate decreased from 90 +/- 13 to 84 +/- 13 beats/min at stage 1 (p < 0.05) and persisted throughout the study with maximum decrease of 14 percent occurring at stage 3. The cardiac index decreased significantly from 2.4 +/- 0.3 to 2.0 +/- 0.5 L/min/m2 (p < 0.05) at stage 1. This persisted throughout the study except that it recovered at stage 4. The maximum decrease in cardiac index (20%) occurred at stage 2. In addition, systemic vascular resistance increased significantly from 1458 +/- 255 to 1830 +/- 420 dyne.sec.cm-5 (p < 0.05) at stage 1 and persisted throughout the study period. We conclude that passive leg raising should be undertaken with caution in patients with coronary artery disease especially in those who have poor left ventricular function.

Aged↗
PubMedDate not supplied

Control of tachycardia and hypertension following coronary artery bypass graft surgery: efficacy and haemodynamic effects of esmolol.

Hypertension following coronary artery bypass grafting is not uncommon, especially in patients having good left ventricular function. It is often accompanied by tachycardia. The purpose of this study is to determine the efficacy of esmolol in the treatment of tachycardia and hypertension immediately following cardiopulmonary bypass and to study other haemodynamic effects of esmolol. Thirty patients undergoing elective [corrected] coronary artery bypass grafting were included in this prospective study. Morphine-based anaesthetic technique along-with standard bypass techniques were used in all the patients. The study was performed in the operating room about 30-45 minutes after the termination of cardiopulmonary bypass. Patients having a heart rate of more than 90 bpm and systolic blood pressure of more than 130 mm Hg without any inotropic support were included and randomly assigned to esmolol or control group. Esmolol was administered in a bolus dose of 500 micrograms/kg followed by infusion of upto 100 micrograms/kg/min. The patients in the control group were administered comparable volumes of normal saline. Baseline haemodynamic measurements were obtained just before the administration of esmolol or normal saline and were repeated after 5, 10, 15, 30 and 45 min. The baseline measurement in both the groups showed that patients were maintaining a state of hyperdynamic circulation with high systolic blood pressure (esmolol group 148 +/- 15 mm Hg, control group 140 +/- 8 mm Hg; p = NS), heart rate (esmolol group 128 +/- 17 bpm, control group 127 +/- 17 bpm; p = NS) and cardiac index (esmolol group 3.1 +/- 1 L/min/m2, control group 3.3 +/- 0.5 L/min/m2; p = NS). Esmolol decreased systolic blood pressure (p < 0.001), heart rate (p < 0.01) and cardiac index (p < 0.05) at five minutes. These changes persisted throughout the study period. The left ventricular stroke work index decreased at five minutes (p < 0.05) and remained so till 30 minutes. The maximum fall in heart rate (15%) and systolic blood pressure (16%) was observed at 45 minutes. There were no haemodynamic changes in the control group except that cardiac index, stroke volume and left ventricular stroke work index increased at five minutes. We conclude that esmolol lowers the indices of cardiovascular work in patients who demonstrated hyperdynamic circulation. This was achieved by decreasing the heart rate and systolic blood pressure which was accompanied by decrease in cardiac index and left ventricular stroke work index.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Cannulation of the internal jugular vein in patients undergoing open heart surgery.

A total of 476 internal jugular vein cannulations performed between June 1990 to August 1991 were prospectively evaluated. The patients' age ranged between ten days to 61 years. We achieved a high success rate of cannulation (97.9%). We describe the use of two single lumen catheters inserted through right internal jugular vein as an alternative to the popular multilumen catheters. We also suggest that low approach should be tried more often in children, if the central approach fails.

Adolescent↗
PubMedDate not supplied

Mechanical ventilation after open heart surgery.

One hundred adult patients, undergoing elective open heart surgery over a period of 4 months, were studied to assess the practice of ventilation in the post operative period. The anaesthetic technique employed used moderate doses of morphine, supplemented with halothane and a muscle relaxant. The decision to extubate was based on clinical assessment, and satisfactory blood gases following a 45 minute T-piece trial. The patients were ventilated for an average duration of 8 hours and 2 minutes and 59 out of 100 patients were extubated within 8 hours. Patients undergoing coronary artery bypass graft were ventilated for significantly longer durations (10 hours 28 minutes) (p < 0.05) and had significantly lower arterial oxygen tension (p < 0.01) 30 minutes after extubation, as compared with those undergoing valvular surgery. Also patients whose bypass time exceeded 2 hours had significantly longer extubation times (p < 0.05) as compared with those who had a bypass time less than 1 hour. T piece trial was found to be a satisfactory method of weaning in all the patients.

Adult↗
PubMedDate not supplied

Surgical management of cardiac myxomas.

Cardiac myxomas are rare cardiac lesions, though they are the commonest tumours of the heart. Seventeen cases of cardiac myxomas have been operated during the last one decade. Exertional dyspnoea, palpitation and chest pain were the main presenting symptoms. Echocardiographic assessment was the only definitive diagnostic investigation required prior to surgery. Early surgical excision was planned in all the cases. Irrespective of the exposure techniques, removal of the tumour with wide excision of its base was practised. There was one early death due to low cardiac output in a patient brought in a shock like state. Follow up study has revealed 14 patients in NYHA class I and two patients are having class II symptoms. Periodic echocardiographic follow up study has not revealed any recurrence till date. It is concluded that an early diagnosis and surgery gives excellent long term results in these cases.

Adult↗
PubMedDate not supplied

Blood conservation in valve surgery.

Blood utilization in 40 patients undergoing elective valve surgery was prospectively studied. The patients had valvular lesions of rheumatic origin with a mean age of 29.1 years and a mean preoperative hematocrit of 35.23 +/- 4.16. Blood was removed from all patients after induction of anesthesia and reinfused after bypass (mean 365.12 +/- 66.96 ml). Membrane oxygenator was used in all the patients. All discard suction was routed through a regionally heparinised collecting and processing system, and the resulting red cell concentrate was transfused. At the conclusion of bypass, all blood remaining in the pump oxygenator was also processed by cell saver and used for subsequent reinfusion. Normovolemic anemia was accepted in hemodynamically stable patients. Thirty two patients (80%) received no bank blood or blood products during their entire hospital course. A total of twelve units of whole blood was transfused into eight patients.

Adolescent↗