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Biomedical subjects

Charles D Deakin

Publications and source records attributed to Charles D Deakin.

24 records · Page 2Linked to original sources
PubMed2004

The incidence and severity of cutaneous burns following external DC cardioversion.

INTRODUCTION: Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion, but the incidence and severity have never been quantified. MATERIALS AND METHODS: Two hours after elective DC cardioversion in 83 sequential patients, we measured skin temperature, erythema index, and minimum sensory and pain detection thresholds at paddle sites and control sites on the contralateral side. Visual analogue pain score (VAS) was recorded at 2 and 24h post-cardioversion. RESULTS: Values for areas over paddle sites were higher (P < 0.05) than control site for all variables measured at 2h. Eighty-four percent patients experienced some pain and 23% patients experienced moderate to severe pain as assessed by VAS. Burns were greater at the edge than the centre of sternal sites and greater at sternal than apical sites. There were positive correlations between transthoracic impedance (TTI) and total energy delivered (r(2) = 0.048; P = 0.04); total energy and pain at 2 h (r(2) = 0.38; P < 0.0001) and 24 h (r(2) = 0.23; P < 0.0001); and number of shocks and pain at 2 h (r(2) = 0.36; P < 0.0001) and 24 h (r(2) = 0.19; P < 0.0001). CONCLUSION: Elective DC cardioversion causes burns as measured by skin temperature, erythema index and sensory threshold to sharp touch. Pain experienced is related to the total energy and number of shocks delivered. To reduce burns, operators should apply optimal paddle force equally to both paddles, with the paddles applied so as to provide even contact along their edges. Burns may also be minimised by starting with lower energy shocks.

Adult↗
PubMed2004

External defibrillation in the left lateral position--a comparison of manual paddles with self-adhesive pads.

INTRODUCTION: Firm paddle force during defibrillation lowers transthoracic impedance (TTI) and increases transmyocardial current, increasing the chances of successful cardioversion. Current protocols recommend that if defibrillation using the anterior-apical (AA) paddle position fails, the anterior-posterior (AP) position should be used. This generally requires the patient to be placed in the left lateral position with the operator leaning over the patient. Avoiding physical contact with the patient during defibrillation subjectively makes application of firm paddle force difficult in the AP position. We compared TTI between the AA and AP positions and between manual paddles and self-adhesive pads to establish if the AP position precludes firm paddle force and to compare TTI between paddles and self-adhesive pads. METHODS: Twenty-one consecutive patients undergoing elective cardioversion (age 39-82) were studied. TTI was measured between pairs of manually held paddles and self-adhesive pads using AA placement with the patient supine, and AP placement with the patient left lateral position. RESULTS: Mean TTI using the AP electrode position was lower using manual paddles (66.5 Omega; 95% CI 60.2-72.9 Omega) than that using self-adhesive pads (92.1 Omega; 95% CI 81.5-102.7 Omega; 95% CI between the mean =15.8-35.5 Omega; P <0.0001). TTI was significantly less using the manual paddles compared with self-adhesive pads in both AA and AP positions (P <0.0001). CONCLUSION: Despite the subjective difficulties of defibrillating patients in the AP position whilst leaning over them, use of manual paddles achieves a lower TTI than that achieved with self-adhesive pads.

Adult↗
PubMed2004

Prehospital end-tidal carbon dioxide concentration and outcome in major trauma.

BACKGROUND: End-tidal carbon dioxide (Petco2) concentration is a marker of the pathophysiologic state because it is a reflection of cardiac output. Petco2 correlates with outcome after prehospital primary cardiac arrest, but association with outcome from prehospital trauma has not been established. METHODS: Between 1998 and 2001, Petco2 was recorded in 191 blunt trauma patients requiring prehospital intubation. Rapid sequence intubation was performed using suxamethonium (1 mg/kg) and etomidate (0.2-0.3 mg/kg). Initial Petco2 after endotracheal intubation (t0) and Petco2 at 20 minutes after endotracheal intubation (t20) were recorded, together with survival to discharge. RESULTS: Median Petco2 at t20 was 4.10 kPa in survivors and 3.50 kPa in nonsurvivors (95% confidence interval of difference between medians, 0.40 to 0.90 kPa; p < 0.0001). Petco2 at t20 was a better predictor of outcome than at t0. CONCLUSION: Only 5% patients with Petco2 < 3.25 kPa survived to discharge. Petco2 at t20 is of value in predicting outcome from major trauma.

Adolescent↗
PubMed2003

Is the orientation of the apical defibrillation paddle of importance during manual external defibrillation?

OBJECTIVE: Transthoracic impedance (TTI) is a factor determining the magnitude of the transmyocardial current during external defibrillation. Minimising TTI increases the chances of successful defibrillation. Most external defibrillation paddles are rectangular in shape and can, therefore, be placed in a transverse or longitudinal orientation. The apical paddle is often placed in a transverse orientation. This may theoretically result in a higher TTI than a longitudinal orientation because of poorer contact at the lateral paddle edges. We compared TTI with the apical paddle in both a transverse and longitudinal orientation. MATERIALS AND METHODS: Twenty sequential anaesthetised patients were studied. A pair of defibrillator paddles were instrumented to measure paddle force. TTI was recorded pre-operatively at end-expiration with the apical paddle in both longitudinal and transverse orientations. The sternal paddle was placed in a longitudinal orientation for all measurements. RESULTS: TTI decreased in both transverse and longitudinal orientations as paddle force increased. Transverse paddle orientation resulted in a significantly (P<0.01) higher TTI than longitudinal orientation at all paddle forces below 12 kg force. CONCLUSION: The longitudinal orientation of a rectangular defibrillation paddle provides a lower TTI than orientation horizontally.

Electric Countershock↗
PubMed2003

What is the optimal paddle force during paediatric external defibrillation?

INTRODUCTION: Transthoracic impedance (TTI) is a major determinant of transmyocardial current flow, and therefore, the success of defibrillation. European Resuscitation Council (ERC) paediatric guidelines recommend that 'firm' paddle force should be applied to the paddles during defibrillation. No study has yet established the optimal paddle force required to minimise TTI in children of different ages. METHODS: Eighty patients aged 10 weeks to 17 yrs undergoing general anaesthesia for routine surgery were studied. Using defibrillation paddles placed in an anterior-apical position, TTI (Omega) was measured for increasing values of force from 0.5 kgf (baseline) to 6.5 kgf. The optimal force, the force to achieve 95% of the overall reduction in TTI, was then determined. According to current guidelines, paediatric paddles (surface area 16 cm2) were used for infants (< or =10 kg) and adult paddles (82 cm2) for older children. Optimal force was then calculated for infants < or =10 kg, children >10 kg and < or =8 yrs and children 9-17 yrs age. RESULTS: Increasing paddle force from 0.5 kgf progressively decreased TTI. Optimal force using paediatric paddles was 2.9 kgf in infants. Optimal force using adult paddles was 5.1 kgf in children >10 kg but < or = 8 yrs and 5.3 kgf in children aged 9-17 yrs. CONCLUSIONS: Force is an important determinant of TTI and therefore, outcome of defibrillation. It is recommended that a minimum of 3 kgf be applied to paddles when defibrillating infants with paediatric paddles, and a minimum of 5 kgf be applied to all older children when adult paddles are used.

Adolescent↗