Sedation with target-controlled propofol infusion during shoulder surgery under interscalene brachial plexus block in the sitting position

BACKGROUND AND OBJECTIVE

The aim of this study was to assess target-controlled propofol infusion as a technique of sedation for shoulder surgery under interscalene brachial plexus block in the sitting position and to evaluate the effect of sedation on hypotensive/bradycardic events during this procedure.

METHODS

One hundred and forty patients undergoing elective shoulder surgery in the sitting position under interscalene brachial plexus block (with 30 mL of ropivacaine 0.75%) were prospectively enrolled. All patients were premedicated with hydroxyzine 1 mg kg(-1), none received beta-blockers. No patients were given atropine except for the patients who experienced a vasovagal event either during the block procedure or intravenous catheter placement. The target-controlled propofol infusion was started immediately after positioning the patient on the operating table. The initial target concentration was 1 microg mL(-1). The infusion rate was adjusted every 15 min by increasing or decreasing the target concentration by 0.2 microg mL(-1) steps to maintain the patient rousable to verbal commands (score of 3 on Wilson sedation scale). The following parameters were assessed: minimal, maximal, optimal target concentration, respiratory and haemodynamic parameters, total propofol dose, additional alfentanil needs, occurrence of hypotensive/bradycardic events, complications. Results are mean +/- SD. Statistical analysis used t-test and chi2-tests.

RESULTS

The optimal propofol target concentration was 0.8 mug mL(-1). No respiratory complications or conversion to general anaesthesia was reported. Two patients experienced transient and inconsequential intraoperative agitation. The incidence of hypotensive/bradycardic events during the procedure was 5.7% (eight patients).

CONCLUSION

Target-controlled propofol infusion (0.8-0.9 microg mL(-1)) following hydroxyzine premedication is a safe and effective technique for sedation when combined with interscalene brachial plexus block during shoulder surgery in the sitting position.

Analgesia after arthroscopic rotator cuff repair: subacromial versus interscalene continuous infusion of ropivacaine

OBJECTIVES

A continuous infusion of local anesthetic in the subacromial space has been shown to provide superior pain relief compared with placebo. This technique has been considered as an alternative to a continuous interscalene infusion. The aim of our study is to compare these 2 techniques for pain relief after arthroscopic rotator cuff repair.

METHODS

In a prospective randomized trial, 30 consecutive patients undergoing rotator cuff repair were included. An interscalene brachial plexus block was performed in all patients with mepivacaine 1.5% 30 mL. Then, 15 patients had an indwelling interscalene catheter inserted immediately after the block via a needle. Fifteen other patients had a subacromial catheter placed at the end of surgery by the surgeon. In both groups, a 2 mg/mL ropivacaine continuous infusion (5 mL/h) with PCA bolus (5 mL/30 min) was maintained for 48 hours. Pain was assessed in PACU and at 24 and 48 hours after surgery, at rest, and during passive motion. Total amount of oral morphine self-administered as rescue analgesia and cumulative 24-hour and 48-hour local anesthetic consumption were noted. Patient satisfaction and side effects were also noted.

RESULTS

Pain during motion in PACU (0 [0 to 60] v 40 [0 to 100] mm) and at 24 hours (10 [0 to 60] v 45 [20 to 100] mm), oral morphine (0 [0 to 6] v 3.5 [0 to 10] morphine capsules), and total amount of local anesthetic at 24 hours (122.5 [120 to 170] v 143 [129 to 250] mg) were lower in the continuous interscalene group. Local anesthetic side effects were less frequent in the continuous subacromial group. Satisfaction was comparable between groups.

CONCLUSION

After arthroscopic rotator cuff repair, continuous interscalene block provides better analgesia compared with continuous subacromial infusion but with an increased incidence of minor side effects.

Pleural effusion and chest pain after continuous interscalene brachial plexus block

OBJECTIVE

We describe a unique case of a patient who experienced atelectasis of the lower lobe of the left lung and pleural effusion manifested by chest pain after continuous interscalene brachial plexus block for postoperative analgesia.

CASE REPORT

A 45-year-old man with no respiratory disease was scheduled for left shoulder arthroscopy for rotator cuff repair under interscalene brachial plexus block and sedation. A continuous interscalene brachial plexus block provided postoperative analgesia. On the first postoperative day, the patient reported left-sided chest pain. The chest x-ray showed elevation of the left hemidiaphragm associated with a left lower lobe atelectasis and a minor pleural effusion. After catheter removal, clinical and radiologic signs resolved within few days without sequela.

CONCLUSION

If chest pain presents after interscalene brachial plexus block, early postoperative chest x-ray is recommended to rule out pneumothorax, atelectasis, and/or pleural effusion secondary to ipsilateral phrenic block.

Intrathecal morphine provides better postoperative analgesia than psoas compartment block after primary hip arthroplasty

PURPOSE

Intrathecal morphine and psoas compartment block represent two accepted techniques to provide postoperative analgesia after hip arthroplasty. We designed a prospective, randomized, single-blinded study to compare these two techniques.

METHODS

Patients scheduled for primary hip arthroplasty under general anesthesia were randomized to receive either an intrathecal administration of 0.1 mg morphine (Group I, n = 27) or a psoas compartment block with ropivacaine 0.475% 25 mL (Group II, n = 26). Pain scores, morphine consumption, associated side-effects were assessed for 48 hr postoperatively. In addition, patient's acceptance and satisfaction of the postoperative analgesic technique were also recorded.

RESULTS

During the first 24 hr, pain scores (3.3 +/- 9.6 mm vs 22.8 +/- 27.1 at H+6, 3.3 +/- 8.3 mm vs 25 +/- 26.7 mm at H+12, 7 +/- 14.9 mm vs 21.9 +/- 29 mm at H+18) and morphine consumption (0.56 +/- 2.12 mg vs 9.42 +/- 10.13 mg) were lower in Group I than in Group II. Urinary retention was the more frequent side-effect occurring in 37% of cases in Group I vs 11.5% in Group II (P < 0.05). No major complication occurred. Despite better analgesia provided by the use of intrathecal morphine, there was no difference in the satisfaction scores between groups.

CONCLUSION

0.1 mg intrathecal morphine administration provides better postoperative analgesia than single-shot psoas compartment block after primary hip arthroplasty.

Outpatient lower extremity infusions

The considerable development of ambulatory surgery has led to an increase in the number of lower extremity procedures performed in an outpatient setting. More recently, the availability of disposable pumps has allowed us to extend the indications of continuous nerve blocks for ambulatory post-operative pain management. Indications for lumbar plexus continuous blocks include anterior cruciate ligament (ACL) reconstruction and patella repairs as well as frozen knee, whereas continuous sciatic blocks are indicated for major foot and ankle surgery. Different modes of local anaesthetic administration have been applied, including the use of repeated bolus, continuous administration and, more recently, patient-controlled perineural infusions. This latter technique seems to be the preferred mode because it offers the advantage of tailoring the amount of local anaesthetics, mostly 0.2% ropivacaine, to the individual need and also maximizes the duration of infusion for a given volume of local anaesthetic. Although the preliminary reports indicate that lower extremity continuous blocks provide effective post-operative ambulatory analgesia and are safe, especially as a part of a multimodal approach, appropriate training in these techniques represents one of the most important limiting factors of the placement of perineural catheters. Additional research is required to determine the optimal conditions in which these techniques are indicated.

Blocks at the wrist provide effective anesthesia for carpal tunnel release

PURPOSE

Distal blocks are not recommended even for a short procedure when a tourniquet is used. This study was designed to evaluate the tolerance, effectiveness, patient acceptance and safety of distal blocks at the wrist.

METHODS

Consecutive patients (n=273, mean age 53 +/-15 yr) undergoing endoscopic carpal tunnel release with a pneumatic tourniquet were included in this study. The median nerve was blocked 6 cm above the wrist crease by injecting 10 mL of 2% lidocaine and 0.5% bupivacaine (v/v). The ulnar nerve was blocked by injecting 8 mL of the same anesthetic mixture below the flexor carpi ulnaris tendon 6 cm above the wrist crease. Finally, 2 mL of local anesthetic were infiltrated sc and laterally below the crease to block the musculocutaneous nerve. The intensity of the block was evaluated after five, ten and 20 min. In addition, pain associated with block performance and tolerance of the tourniquet were evaluated. Finally, neurological complications associated with this technique were investigated. Data are presented as means +/- SD.

RESULTS

At ten minutes after the block was performed, 9% and 32% of patients required an additional injection to complete the block in the median and ulnar territories, respectively. In more than 75% of patients, performance of the block was associated with either no or mild pain. The tourniquet was inflated for 12.6 +/- 5.4 min and was well tolerated in 99% of patients. Finally, neither transient nor permanent neurological deficit were recorded postoperatively.

CONCLUSION

Blocks at the wrist are effective, well accepted by the patient and safe when a pneumatic tourniquet is used for a short procedure.

A new anterior approach to the sciatic nerve block

BACKGROUND

Although several anterior approaches to sciatic nerve block have been described, they are used infrequently. The authors describe a new anterior approach that allows access to the sciatic nerve with the patient in the supine position.

METHOD

Sciatic nerve blocks were performed in 22 patients. A line was drawn between the inferior border of the anterosuperior iliac spine and the superior angle of the pubic symphysis tubercle. Next, a perpendicular line bisecting the initial line was drawn and extended 8 cm caudad. The needle was inserted perpendicularly to the skin, and the sciatic nerve was identified at a depth of 10.5 cm (9.5-13.5 cm; median and range) using a nerve stimulator and a 15-cm b-beveled insulated needle. After appropriate localization, either 30 ml mepivacaine, 1.5% (group 1 = knee arthroscopy; n = 16), or 15 ml mepivacaine, 1.5%, plus 15 ml ropivacaine, 0.75%, (group 2 = other procedures; n = 6) was injected.

RESULTS

Appropriate landmarks were determined within 1.3 min (0.5-2.0 min). The sciatic nerve was identified in all patients within 2.5 min (1.2-5 min), starting from the beginning of the appropriate landmark determination to the stimulation of its common peroneal nerve component in 13 cases and its tibial nerve component in 9 cases. A complete sensory block in the distribution of both the common peroneal nerve component and the tibial nerve component was obtained within 15 min (5-30 min). A shorter onset was observed in patients who received mepivacaine alone compared with those who received a mixture of mepivacaine plus ropivacaine (10 min [5-25 min] vs. 20 min [10-30 min]; P < 0.05). Recovery time was 4.6 h (2.5-5.5 h) after mepivacaine administration. The addition of ropivacaine produced a block of a much longer duration 13.8 h (5.2-23.6 h); P < 0.05. No complications were observed.

CONCLUSIONS

This approach represents an easy and reliable anterior technique for performing sciatic nerve blocks.

Clonidine does not impair redistribution hypothermia after the induction of anesthesia

Clonidine is commonly given for premedication, and it impairs normal thermoregulatory responses to warm and cold stimuli while depressing sympathetic tone. We studied the effect of premedication by clonidine on redistribution hypothermia induced by the induction of anesthesia. Sixteen ASA physical status I or II patients were randomly assigned to receive either clonidine 150 micrograms or a placebo. Anesthesia was induced 45 min later by thiopental, fentanyl, and vecuronium i.v. and was maintained by the administration of 0.6% isoflurane. We monitored central core (tympanic) temperature and skin surface temperatures at the forearm and the fingertip during the 2 h after the induction of anesthesia before surgery. We estimated skin blood flow at the level of the forearm by using laser Doppler during the same period. The core temperature decreased comparably in the two groups of patients, from 37.1 +/- 0.2 degrees C to 35.3 +/- 0.4 degrees C and from 37.1 +/- 0.2 degrees C to 35.5 +/- 0.3 degrees C in the clonidine and placebo groups, respectively. The forearm-fingertip surface temperature gradient decreased similarly in the two groups. There was no evidence of cutaneous vasoconstriction. The laser Doppler index at the fingertip increased similarly in the two groups, as did the forearm-fingertip temperature gradient. We conclude that premedication with clonidine does not significantly impair the profile of central hypothermia induced by heat redistribution after the induction of anesthesia.

IMPLICATIONS

The induction of general anesthesia is associated with redistribution hypothermia. This study shows that premedication with oral clonidine does not worsen the decrease in core temperature resulting from general anesthesia.

Infection risk and cost-effectiveness of commercial bags or glass bottles for total parenteral nutrition

OBJECTIVE

To determine whether the greater daily expense of administering total parenteral nutrition (TPN) via plastic bags changed once daily, compared to glass bottles changed thrice daily, could be offset by savings from a reduction in nosocomial infections.

DESIGN

The costs and potential benefits of commercially available TPN bags and TPN in glass containers were compared. Costs were computed from the viewpoint of the hospital, first in a general model and then for two specific examples, Crohn's disease and intensive-care unit (ICU) patients. The extra cost of using bags was $20 per day. The total cost of nosocomial bacteremia was estimated at $6,000. The monetary benefits of using TPN bags were $6,000XT, where XT was the percentage of nosocomial infections averted. We also considered that reduction in intravenous (IV)-line manipulation could reduce bacteremia-related mortality and computed a cost-per-life-saved ratio.

RESULTS

Modeling showed that TPN in bags could yield a net benefit when the absolute reduction in the daily risk of nosocomial bacteremia reached the threshold value of 0.3%. Such a reduction could not be attained in patients with Crohn's disease, and corresponded to a 50% to 60% reduction of infection rates in ICU patients. Varying the risk of mortality attributable to IV-line-related infection from 1% to 13% resulted in a cost effectiveness of using TPN bags ranging from $90,000 to $7,000 per life saved in ICU, assuming a two-thirds reduction in IV-line infections, and from $180,000 to $14,000 if the infection rate was reduced by one third.

CONCLUSION

The baseline cost-minimization analysis concluded that the extra cost of TPN bags was not justified by the extra savings. The cost-effectiveness analysis, however, found that the cost per life saved fell within the accepted range of public health interventions, provided a large fraction of infections are averted using TPN bags.

Clonidine increases the sweating threshold, but does not reduce the gain of sweating

We tested the hypothesis that clonidine produces a dose-dependent increase in the sweating threshold but does not reduce the gain of sweating. Six healthy male volunteers were evaluated, each on three separate days in random order. In one, saline was administered; in another, a 2-micrograms/kg bolus of clonidine was followed by an infusion at 2 micrograms.kg-1.h-1, and on a third day, a 4-micrograms/kg bolus was followed by an infusion at 4 micrograms.kg-1.h-1. Core temperature was measured at the tympanic membrane and mean skin temperature was determined from four sites. A chest sweating rate of 40 g.m-2.h-1 was considered significant. The core temperature triggering sweating, adjusted to a designated mean skin temperature of 34 degrees C, identified the threshold for this response. Gain was defined by the adjusted core temperature increase required to augment sweating from 100 to 300 g.m-2.h-1. degree C-1. Plasma clonidine concentrations were 0.8 +/- 0.1 and 1.6 +/- 0.2 ng/mL on the small- and large-dose days, respectively. Clonidine administration increased the sweating threshold approximately 0.4 degree C (P < 0.05), but the increase was comparable at each dose. The gain of sweating was approximately 0.2 degree C and was not influenced by clonidine administration. The thermoregulatory effects of clonidine thus resemble those of volatile anesthetics, opioids, and propofol. These data suggest that the antishivering effect of clonidine results from central thermoregulatory inhibition rather than a specific peripheral action on thermogenic muscular activity. Unlike other sedatives and anesthetics, the concentration-dependence of clonidine demonstrates a ceiling beyond which the administration of an additional drug fails to enhance the effect, suggesting that the thermoregulatory effect of clonidine may be limited, even at high plasma concentrations. The gain of sweating was well preserved indicating that this response remains effective in the presence of sedatives and anesthetics.

Bilateral massive adrenal haemorrhage complicating anaphylactic shock: a case report

A case of bilateral adrenal haemorrhage complicating anaphylactic shock is reported. Hypovolemic shock related to peritoneal haemorrhage was the main feature landing to laparotomy. Ultrasonographic examination was not contributive, but CT scan easily documented the adrenal haemorrhage and must be considered a valuable diagnostic tool when adrenal haemorrhage is suspected.

Laparoscopic cholecystectomy minimally impairs postoperative cardiorespiratory and muscle performance

Surgery elicits a subjective feeling of postoperative fatigue, at least partly related to an impairment in cardiorespiratory function and muscle performance. Laparoscopic surgery is reported to impair the patient's condition minimally. The aim of this study was to assess exercise performance in patients scheduled for elective laparoscopic cholecystectomy. Nine patients assessed as having American Society of Anesthesiologists (ASA) grade I were enrolled in the study. Subjective feelings of fatigue (measured on a visual analogue scale), and heart rate, systemic arterial pressure oxygen consumption and carbon dioxide production responses to graded exercise testing, were assessed before operation and on days 3 and 10 after operation. There were no significant differences in any of these measurements, at rest or during exercise, between the preoperative and postoperative values. Uncomplicated laparoscopic cholecystectomy does not impair postoperative cardiorespiratory and muscle performance or induce significant postoperative fatigue in patients with ASA I, allowing rapid recovery.

Systematic transesophageal echocardiography for detection of mediastinal lesions in patients with multiple injuries

A prospective study assessing the interest in and the results of systematic transesophageal echocardiography (TEE) examination in nonselected intubated multiple injury patients was carried out from January 1992 through June 1993. Seventy patients were included and divided into two groups according to the results of admission screening, including clinical examination, EKG, CK-MB and chest radiograph. Group 1 (60 patients) had abnormalities on initial screening, while group 2 (10 patients) had no symptom of thoracic or mediastinal injury. TEE was performed within 48 hours following admission and its results were compared with those of the initial screening. TEE usefulness was evaluated on a score grade from 0 (no interest) to 4 (outstanding interest). Myocardial contusion was suspected in 25 patients. TEE invalidated 18 suspected and found 5 unsuspected myocardial contusions. Pericardial effusion was suspected in only one case, while TEE documented 13 additional cases. A mediastinal enlargement was seen in 13 patients, but TEE invalidated aortic lesions in all these cases and made an unsuspected diagnosis of aortic tears. Eight cases of severe hypovolemia and seven cases of left ventricle dysfunction were detected by TEE. The score of interest showed that TEE allowed new interesting diagnoses in 70% of group I patients and in 33% of group II patients. TEE is of utmost importance in multiple injury patients, with or without any evidence of thoracic or mediastinal injury, providing a safe and rapid examination of the mediastinal structures and an evaluation of the hemodynamic status.