U. Aromaa

Transient radicular irritation after spinal anesthesia induced with hyperbaric solutions of cerebrospinal fluid-diluted lidocaine 50 mg/ml or mepivacaine 40 mg/ml or bupivacaine 5 mg/ml

Background: Transient radicular irritation (TRI) is common after spinal anesthesia induced with hyperbaric lidocaine 50 mg/ml. The purpose of this study was to determine the incidence of TRI after spinal anesthesia with hyperbaric lidocaine 50 mg/ ml diluted with cerebrospinal fluid (CSF) 1:1 and hyperbaric mepivacaine 40 mg/ml and hyperbaric bupivacaine 5 mg/ml.

Venous Complications After Intravenous Injection of Diazepam, Flunitrazepam, Thiopentone and Etomidate

The Occurrence of phlebitis, thrombosis, and thrombophlebitis after intravenous premedication with diazepam (0.15 mg/kg) dissolved in propylene glycol (Valium®) or in polyethylene glycol (Diapam®) or flunitrazepam (0.0125 mg/kg), and after intravenous induction of balanced general anaesthesia with thiopentone (4.0 mg/kg) or etomidate (0.3 mg/kg) was studied on the 7th and 14th postoperative days in 115 patients undergoing short‐stay varicose vein surgery. Venous complications occurred most frequently after etomidate (43% at 14 days), thiopentone (23% at 14 days), and Valium (21 % at 7 days). Diapam caused fewer venous sequelae (9% at 14 days) than Valium (18 % at 14 days), but the smallest number of complications were noticed after flunitrazepam (8% at 7 days and none at 14 days). Venous sequelae were more severe and more extended after thiopentone and after etomidate than those after the diazepam preparations. It is concluded that venous complications after flunitrazepam premedication were mild and infrequent and that the incidence of such complications was unacceptably high after etomidate induction.

Double-blind comparison of transdermal scopolamine, droperidol and placebo against postoperative nausea and vomiting

Since transdermal scopolamine (TS) seems effective against seasickness, we compared its antiemetic effect with intravenous droperidol (DHBP), our routine antidote for postoperative emesis. Ninety–six female patients (ASA I–II) scheduled for short–stay surgery were randomly allocated to three study groups after giving their informed consent. The three groups were as follows: TS adhesive, delivering 140 μg initially and 5 μg/h thereafter + placebo 0.5 ml i.v. 5 min before the end of surgery; transdermal placebo adhesive preoperativcly + DHBP 0.5 ml (1.25 mg) i.v. 5 min before the end of surgery; transdermal placebo+ 0.5 ml placebo i.v. as indicated above. Oxycodone i.m. and glycopyrrolate i.v. were given for premedication together with the test adhesive. Anaesthesia was induced with thiopental and maintained with nitrous oxide and oxygen, enflurane, vecuronium and fentanyl. Neostigmine and glycopyrrolate were administered for reversal. In the recovery room no differences in nausea or vomiting were observed between the groups. Sedation was significantly more marked (P < 0.15–0.0001) after DHBP than after either TS or the placebo. An additional 1.25 mg DHBP was required in 28% of the patients given TS compared with 13% of those given DHBP and 6%, of those given the placebo (P <0.05). During the following 24 h nausea was reported more by the placebo patients (25) than by those on TS (20) or DHBP (15) (P <0.05). However, actual vomiting on the ward did not differ between the groups. Visual disturbances were more frequent after TS (P <0.01). We conclude that prophylactic transdermal scopolamine does not diminish postoperative emetic sequelae.

Verification of the position of a central venous catheter by intra‐atrial ECG. When does this method fail?

The purpose of this study was to determine why intra‐atrial ECG tracing for checking the position of a central venous catheter fails in certain patients. Three hundred and fifty prospective and consecutive patients scheduled for central venous catheterization using various puncture sites and techniques were investigated. The catheters were 20 cm in length. After its introduction, the catheter was connected to an Alphacard® (Sterimed, Saarbrücken) for the intra‐atrial ECG tracing. The method failed in 29 patients, of whom nine had manifest myocardial pathology. In two patients the catheter looped, while in the remaining 18 the catheter proved to be too short. In these 18 patients, the cannulation was mainly performed via the external jugular vein and/or from the left side. Most of the patients were elderly males, and 11 of the 18 patients showed radiological signs of pulmonary emphysema. In such individuals it is advisable to use a catheter longer than 20 cm.

Difficulties with tooth protectors in endotracheal intubation

The suitability of three tooth protectors for routine use during endotracheal intubation was studied in 300 consecutive patients undergoing elective operations under general anaesthesia. The main disadvantages of the protectors were lack of space and the consequent difficulty of guiding the endotracheal tube into the larynx, and poor visibility, especially when the Camo® protector was used. These difficulties could be avoided in most cases by cutting off the right angle of the Camo protector. The less experienced anaesthesiologists especially had difficulties with the protectors: 20% of patients in the Camo group were considered impossible to intubate unless the protector was removed. The silicone inlay of the Camo protector melts and becomes adhesive at body temperature, which makes its prolonged use hazardous. Two patients lost a maxillary incisor despite the proper use of a protector (Denex®). Thus the use of a tooth protector alone does not guarantee avoidance of dental trauma. Better results could be obtained by improving the design of the protectors and by careful pre–anaesthetic dental examination.

The claims of compensation for awareness with recall during general anaesthesia in Finland

Background: Awareness during anaesthesia has been estimated to occur in 0.2%‐0.4% of patients undergoing general surgery. In Finland, according to the Patient Injury Act, compensation is paid for an injury caused by medical treatment. We have analysed the claims for compensation involving awareness under anaesthesia filed between May, 1987 and December, 1993.

Epinephrine added to a lumbar epidural infusion of a small-dose ropivacaine-fentanyl mixture after arterial bypass surgery of the lower extremities

Background:  The addition of epinephrine (2 µg·ml−1) to a thoracic epidural infusion of an opioid‐local anesthetic mixture improves analgesia. Here, we studied whether epinephrine could improve analgesia also at lumbar level, when added to an epidural infusion of a low‐dose ropivacaine‐fentanyl mixture after arterial bypass surgery of the legs.

The Role of Thiopental and Fentanyl in the Production of Balanced Anaesthesia

In order to clarify the interactions between various doses of thiopental and fentanyl in producing “balanced anaesthesia”, their effects on consciousness, superficial nociception, and respiration and circulation were studied during N2O f O2 inhalation in connection with the induction of anaesthesia. Altogether 60 patients were studied; the drug combinations used were thiopental 5 mg/kg (TPs), thiopental 3 mg/kg (TP,), thiopental 3 mg/kg and fentany1 0.5 μg/kg (TP3Fo5), thiopental 2 mg/kg and fentanyl I pg/kg (TPPFI), thiopental 1 mg/kg and fentanyl 2 μg/kg (TP1F2), and fentanyl 3 μg/kg (F3). Five minutes after the i.v. supplementation of N2O+ O2 anaesthesia, the depth of anaesthesia and analgesia (antinociception) were evaluated from the eyelid reflex and by pinching an inguinal skin fold. Cardiorespiratory parameters were measured during this study period at 1 ‐min intervals.

Ranitidine and prevention of pulmonary aspiration syndrome

Thirty‐seven patients undergoing elective abdominal surgery (excluding gastric operations) received either ranitidine 300 mg or placebo orally at 10 p. m. in the evening preceding surgery in a double‐blind randomised study. The mean time interval between this oral premedication and induction of anaesthesia was 12 h. When compared to placebo, ranitidine decreased significantly (P<0.05) the amount of gastric juice, and none of the ranitidine‐treated patients had an increased risk of acid pulmonary aspiration (pH below 2.5 and volume over 25 ml), while four patients in the control group had an increased risk (21%). The mean ranitidine blood level was 237 ng/ml at the time of induction of anaesthesia. It is concluded that in elective abdominal surgery ranitidine included in the premedication is likely to decrease the risk for acid pulmonary aspiration.

The Role of Halothane and Fentanyl in the Production of Balanced Anaesthesia

The aim of the study was to quantitate the degree of respiratory depression when tolerance of superficial nociception and of an endotracheal tube was achieved by supplementing N2O + O2 anaesthesia either with halothane alone or with halothane in combination with fentanyl. Eighty‐four patients, matched into sewn groups, were studied after induction of anaesthesia with thiopental (4 mg/kg) and suxamethonium (3 mg/kg) using the following supplementation: 0.8, 0.6, 0.4% halothane alone or 0.4, 0.2, 0% halothane with 0.5‐2 μg/kg fentanyl. After 10 min administration of the anaesthetic mixture using manual intermittent positive pressure ventilation (IPPV) (end‐tidal CO2 c. 5.5%), IPPV was discontinued and spontaneous respiration allowed to return. When the end‐tidal Co2 had stabilized, samples for blood gas analysis were taken and superfirial antinociception was tested by pinching an inguinal skin fold. Supplementation of an N2O + O2 mixture with 0.8% halothane without fentanyl or with 0.4% halothane with 0.5 μg/kg fentanyl seemed to come closest to the optimum in producing tolerance of an endotracheal tube and of superficial nociception (in about 85% of cases) with an increase in PCO2 to only 7 kPa.