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Weight gain during shoulder arthroscopy: a proxy for fluid absorption
38
Posters
•
Peripheral Nerve Blocks I
31. Weight gain during shoulder arthroscopy: a proxy for fluid absorption Sinha A Department of Anaesthesia, St Mary’s Hospital, London, United Kingdom Aims: To quantify the amount of saline absorbed by patients during arthroscopic shoulder surgery using weight gain during surgery as a proxy. Methods: Patients were weighed with an accurate electronic scale (linear response ⫾ 0.1kg within the range of adult weights). Patient weight was recorded immediately before and after arthroscopic shoulder surgery under interscalene block (n ⫽ 40). An FMS 4 pump was used. The surgeon determined the pump pressure. In calculating weight gain during surgery, account was taken of the weight of drugs, dressings and slings, and whether they were wet or not. No intravenous infusions were given. Data recorded included age, height, pump pressure, duration of surgery and operation. Statistical analysis was performed with t-tests and Pearson’s correlation coefficient where appropriate. Results: Patients gained a median [range] weight of 400 [40-2500] ml. There was no statistically significant difference between weight gain in patients who underwent gleno-humeral or sub-acromial procedures, or between patients operated upon by the two surgeons performing the operations. Weight gain was positively and significantly correlated with duration of surgery and with mean pump pressure. There was no correlation between weight gain (expressed as ml of saline absorbed per unit of the product of pressure and time: ml.mmHg-1.min-1) and patient height, weight or body mass index. However, there was a statistically significant correlation between weight gain and age (p ⬍ 0.05). Conclusions: The volume of fluid absorbed is unlikely to pose a threat to fit patients, however there is an incidence of complication with arthroscopic shoulder surgery.1 For the same pump pressure and duration of surgery, older patients will absorb more fluid from the pump system than younger patients. This, in combination with the known incidence of phrenic nerve paralysis with interscalene block, older patient is more prone to respiratory compromise and congestive cardiac failure.2 Thus, care should be exercised when performing prolonged procedures on these patients. Arthroscopic procedures on patients prone to congestive cardiac failure may not be appropriate training cases.
References 1. McFarland EG, O’Neill OR, Hsu CY. Complications of shoulder arthroscopy. South Orthop Assoc. 1997 Fall;6(3):190-196. 2. Kurt E, Guzeldemir ME. Interscalene brachial plexus block and pulmonary function. Can J Anaesth. 1999 Aug;46(8):808-809.
43. Influence of local anaesthetic concentration on quality of sensory and motor blockade after subclavian brachial plexus anaesthesia Barkas T General Hospital, Larissa, Greece Aim: Ropivacaine used for brachial plexus block provides effective motor and sensory blockade. Varying clinical dosage recommendations exist. We compared the behaviour of two different concentrations of Ropivacaine in a 30mL injection volume for subclavian (brachial) plexus block. Methods: 30 patients (ASA I-II, 么/乆; 15/15, Age 25-45, BW: 65-95 kg undergoing elective hand surgery were enrolled in the study after written informed consent. In all patients a subclavicular brachial plexus block was performed. Half of the patients (Group A, n1 ⫽ 15) received 30 ml Ropivacaine 0,375% whereas Group B patients (n2 ⫽ 15) received 30 ml Ropivacaine 0,5%. Standard Monitoring (HR, BP, SPO2) was applied. The two groups were compared for sufficiency of motor and sensory blockade by assessing muscle strength, two-point discrimination and constant-touch sensation. In case of insufficient blockade, additional intravenous sedation was administered. Results: Duration of surgery was comparable in both groups. No differences in oxygen saturation and hemodynamic variables were observed between the two groups. Patients in Group B presented with complete both motor and sensory blockade and no need for additional sedation was recorded. Patients in Group A presented with complete sensory blockade as well, however motor blockade was not satisfactory, thus making operating conditions occasionally problematic. Additional sedation with Remifentanyl 0,1 ␥/kg and 0,2 mg/kg Dormicum was administered. Conclusions: Local anaesthetic concentration is directly related to the success of blockade and thus to the improvement of surgical conditions. Although low concentrations produce sufficient sensory blockade, motor blockade may be insufficient. On the contrary the use of higher concentrations of local anaesthetic provides significantly better sensory and motoro blockade.
References 1. Krenn H, et al: Increasing the injection volume by dilution improves the onset of motor blockade, but not sensory blockade of ropivacaine for brachial plexus block. Eur J Anaesthesiol 2003;20(1):21-25.
Posters
•
Peripheral Nerve Blocks I
31. Weight gain during shoulder arthroscopy: a proxy for fluid absorption Sinha A Department of Anaesthesia, St Mary’s Hospital, London, United Kingdom Aims: To quantify the amount of saline absorbed by patients during arthroscopic shoulder surgery using weight gain during surgery as a proxy. Methods: Patients were weighed with an accurate electronic scale (linear response ⫾ 0.1kg within the range of adult weights). Patient weight was recorded immediately before and after arthroscopic shoulder surgery under interscalene block (n ⫽ 40). An FMS 4 pump was used. The surgeon determined the pump pressure. In calculating weight gain during surgery, account was taken of the weight of drugs, dressings and slings, and whether they were wet or not. No intravenous infusions were given. Data recorded included age, height, pump pressure, duration of surgery and operation. Statistical analysis was performed with t-tests and Pearson’s correlation coefficient where appropriate. Results: Patients gained a median [range] weight of 400 [40-2500] ml. There was no statistically significant difference between weight gain in patients who underwent gleno-humeral or sub-acromial procedures, or between patients operated upon by the two surgeons performing the operations. Weight gain was positively and significantly correlated with duration of surgery and with mean pump pressure. There was no correlation between weight gain (expressed as ml of saline absorbed per unit of the product of pressure and time: ml.mmHg-1.min-1) and patient height, weight or body mass index. However, there was a statistically significant correlation between weight gain and age (p ⬍ 0.05). Conclusions: The volume of fluid absorbed is unlikely to pose a threat to fit patients, however there is an incidence of complication with arthroscopic shoulder surgery.1 For the same pump pressure and duration of surgery, older patients will absorb more fluid from the pump system than younger patients. This, in combination with the known incidence of phrenic nerve paralysis with interscalene block, older patient is more prone to respiratory compromise and congestive cardiac failure.2 Thus, care should be exercised when performing prolonged procedures on these patients. Arthroscopic procedures on patients prone to congestive cardiac failure may not be appropriate training cases.
References 1. McFarland EG, O’Neill OR, Hsu CY. Complications of shoulder arthroscopy. South Orthop Assoc. 1997 Fall;6(3):190-196. 2. Kurt E, Guzeldemir ME. Interscalene brachial plexus block and pulmonary function. Can J Anaesth. 1999 Aug;46(8):808-809.
43. Influence of local anaesthetic concentration on quality of sensory and motor blockade after subclavian brachial plexus anaesthesia Barkas T General Hospital, Larissa, Greece Aim: Ropivacaine used for brachial plexus block provides effective motor and sensory blockade. Varying clinical dosage recommendations exist. We compared the behaviour of two different concentrations of Ropivacaine in a 30mL injection volume for subclavian (brachial) plexus block. Methods: 30 patients (ASA I-II, 么/乆; 15/15, Age 25-45, BW: 65-95 kg undergoing elective hand surgery were enrolled in the study after written informed consent. In all patients a subclavicular brachial plexus block was performed. Half of the patients (Group A, n1 ⫽ 15) received 30 ml Ropivacaine 0,375% whereas Group B patients (n2 ⫽ 15) received 30 ml Ropivacaine 0,5%. Standard Monitoring (HR, BP, SPO2) was applied. The two groups were compared for sufficiency of motor and sensory blockade by assessing muscle strength, two-point discrimination and constant-touch sensation. In case of insufficient blockade, additional intravenous sedation was administered. Results: Duration of surgery was comparable in both groups. No differences in oxygen saturation and hemodynamic variables were observed between the two groups. Patients in Group B presented with complete both motor and sensory blockade and no need for additional sedation was recorded. Patients in Group A presented with complete sensory blockade as well, however motor blockade was not satisfactory, thus making operating conditions occasionally problematic. Additional sedation with Remifentanyl 0,1 ␥/kg and 0,2 mg/kg Dormicum was administered. Conclusions: Local anaesthetic concentration is directly related to the success of blockade and thus to the improvement of surgical conditions. Although low concentrations produce sufficient sensory blockade, motor blockade may be insufficient. On the contrary the use of higher concentrations of local anaesthetic provides significantly better sensory and motoro blockade.
References 1. Krenn H, et al: Increasing the injection volume by dilution improves the onset of motor blockade, but not sensory blockade of ropivacaine for brachial plexus block. Eur J Anaesthesiol 2003;20(1):21-25.