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Biomedical subjects

M K Karmakar

Publications and source records attributed to M K Karmakar.

At least 19 recordsLinked to original sources
PubMed2007

Decision analysis.

Explore the source record for details and available documents.

Decision Support Techniques↗
PubMed2006

Dynamic airflow limitation after topical anaesthesia of the upper airway.

This prospective before-and-after observational study investigated the effect of upper airway anaesthesia on dynamic airflow. Six consenting ASA 1 adults, all authors of this study, underwent a series of spirometric measurements before and after topical anaesthesia of the upper airway using lignocaine. Peak inspiratory flow rate, forced inspiratory flow between 25% and 75% of the maximum inhaled volume, forced expiratory volume at 1 second, and forced vital capacity in the supine and sitting positions were measured. The measured inspiratory parameters were significantly reduced after lignocaine topical anaesthesia of the upper airway. Expiratory flow parameters were not affected. We conclude that topical anaesthesia of the upper airway leads to dynamic inspiratory airflow limitation.

Administration, Topical↗
PubMed2005

Central apnoea after balanced general anaesthesia that included dexmedetomidine.

Dexmedetomidine is an alpha(2)-adrenoreceptor agonist that, in spite of its potent sedative, amnesic, and analgesic properties, has minimal respiratory depressant effect. Even at doses adequate for general anaesthesia, it does not cause central apnoea. Thus, it has been claimed that "combining alpha(2)-agonists with opiate narcotics or non-steroidal anti-inflammatory drugs can enhance the analgesic efficacy without increasing the respiratory depressant effect of the latter" and "the combination of alpha(2)-adrenoceptor agonists with opioids does not lead to further ventilatory depression". We present a case of central apnoea after general anaesthesia that included opioids and dexmedetomidine, and remind the readers that in susceptible patients, dexmedetomidine may cause life-threatening respiratory depression through potentiation of co-administered central nervous system depressants.

Adrenergic alpha-Agonists↗
PubMed2005

Accuracy of central venous pressure monitoring during simultaneous continuous infusion through the same catheter.

Continuous central pressure monitoring and simultaneous continuous infusion via the same central venous catheter are sometimes necessary. Based on theoretical calculations and experimental measurements, we have determined that pressure monitoring is essentially unaffected if the continuous infusion rate is 50 ml.h(-1) or less for an adult and a paediatric central catheter. At rates > 200 ml.h(-1), the central venous pressure is exaggerated by up to 4 mmHg and 8 mmHg for the adult and paediatric catheters, respectively.

Adult↗
PubMed2004

Right thoracic paravertebral analgesia for hepatectomy.

Haemostatic deficiencies, common among cirrhotic patients, may deteriorate further after hepatectomy, increasing the bleeding risk associated with the use of thoracic epidural analgesia. We describe two patients who enjoyed immediate post-operative tracheal extubation and satisfactory analgesia using mainly right thoracic paravertebral analgesia after right lobe hepatectomy.

Analgesia, Epidural↗
PubMed2002

The margin of safety associated with the use of cuffed paediatric tracheal tubes.

There is increasing interest in the use of cuffed paediatric tracheal tubes, these tubes have a number of advantages and disadvantages. One disadvantage is the decreased margin of safety associated with the use of cuffed tracheal tubes. When using an uncuffed tube, the margin of safety is approximately the length of the trachea, however, for a cuffed tube, this margin is reduced and is the length of the trachea minus the distance between the proximal edge of the cuff and the and the tip of the tube. We have found that, compared with traditional uncuffed tubes, cuffed tubes may be associated with a reduced margin of safety of approximately 50% or more.

Age Factors↗
PubMed2002

Local anaesthesia outside the operating room.

An increasing number of minor surgical procedures are performed under local anaesthesia in clinical settings outside the operating room, where monitoring and resuscitation equipment--as well as personnel skilled in resuscitation--may not be readily available. Serious adverse effects and even fatalities may result from the use of local anaesthetic agents, arising from a variety of causes such as systemic toxicity, allergy, vasovagal syncope, and reaction to additives present in the local anaesthetic. This article briefly reviews the pharmacology of local anaesthetic agents, and describes various techniques commonly used for local anaesthesia, with special emphasis on safety. Clinical features of toxicity, and its differential diagnosis and management, are also discussed.

Anesthesia, Local↗
PubMed2001

Ipsilateral thoraco-lumbar anaesthesia and paravertebral spread after low thoracic paravertebral injection.

We report ipsilateral thoraco-lumbar anaesthesia and paravertebral spread of contrast after injection through a thoracic paravertebral catheter that was placed at the right T8-9 spinal level for pain management in a patient with multiple fractured ribs. We review the literature and describe the subendothoracic fascial communication between the thoracic paravertebral space and the retroperitoneal lumbar paravertebral region, which we propose, is the anatomical basis for ipsilateral thoraco-lumbar anaesthesia and paravertebral spread of contrast in our patient.

Extravasation of Diagnostic and Therapeutic Materi↗
PubMed2000

Thoracic paravertebral block: radiological evidence of contralateral spread anterior to the vertebral bodies.

We report contralateral spread of contrast medium anterior to the vertebral bodies after injection of contrast through a thoracic paravertebral catheter that was used to manage pain in a patient with multiple fractured ribs. We review the literature and propose that the anatomical basis for this observation is spread in the extrapleural compartment of the thoracic paravertebral space along the subserous fascial plane.

Aged↗
PubMed1999

A study to determine the optimum dose of metaraminol required to increase blood pressure by 25% during subarachnoid anaesthesia.

We studied dosage optimization for metaraminol when managing hypotension during subarachnoid anaesthesia. Twenty patients aged 53 to 84 years, were recruited. Non-invasive blood pressure (BP) and heart rate were recorded one-minutely. A series of four i.v. metaraminol boluses (0.25 to 1.0 mg per 50 kg adult) were administered. From individual patient time plots of BP predicted dosages for a 25% elevation in BP were estimated. Dose-related elevations in systolic BP [mean (SD)] occurred following dosages of 0.5 mg [25 (11)%] and 1.0 mg [50 (23)%]. Similar elevations occurred in mean and diastolic BP. Overall estimated dosage (median) to produce a 25% elevation in systolic BP was 0.5 mg (per 50 kg adult). However, individual patient responses varied (10-90th centiles = 0.23 to 0.80 mg). Thus, we now recommend a starting dose of 0.25 mg, increasing to 0.5 mg if necessary, to treat hypotension (25% decrease in systolic BP) during subarachnoid anaesthesia.

Aged↗
PubMed1997

Bilateral continuous paravertebral block used for postoperative analgesia in an infant having bilateral thoracotomy.

We describe the successful postoperative pain management in an 11-month-old infant who underwent bilateral thoracotomy, using continuous infusions of bupivacaine into two directly placed paravertebral catheters. Haemodynamic parameters and pain scores were measured 1-2 h for 60 h while the infusions were continued and, intermittently, blood samples were taken for subsequent measurement of serum bupivacaine concentrations. The technique provided effective pain relief and the infant required no other analgesia postoperatively. There were no adverse haemodynamic consequences or complications relating to either catheter placement or drug infusions. Serum concentrations of bupivacaine remained below toxic levels throughout the study period, though accumulation did occur.

Analgesia↗