Recovery characteristics following induction of anaesthesia with a combination of thiopentone and propofol

Thoracic spinal anesthesia is safe for patients undergoing abdominal cancer surgery

AIM

A double-blinded randomized controlled study to compare discharge time and patient satisfaction between two groups of patients submitted to open surgeries for abdominal malignancies using segmental thoracic spinal or general anesthesia.

BACKGROUND

Open surgeries for abdominal malignancy are usually done under general anesthesia, but many patients with major medical problems sometimes can't tolerate such anesthesia. Regional anesthesia namely segmental thoracic spinal anesthesia may be beneficial in such patients.

MATERIALS AND METHODS

A total of 60 patients classified according to American Society of Anesthesiology (ASA) as class II or III undergoing surgeries for abdominal malignancy, like colonic or gastric carcinoma, divided into two groups, 30 patients each. Group G, received general anesthesia, Group S received a segmental (T9-T10 injection) thoracic spinal anesthesia with intrathecal injection of 2 ml of hyperbaric bupivacaine 0.5% (10 mg) and 20 ug fentanyl citrate. Intraoperative monitoring, postoperative pain, complications, recovery time, and patient satisfaction at follow-up were compared between the two groups.

RESULTS

Spinal anesthesia was performed easily in all 30 patients, although two patients complained of paraesthesiae, which responded to slight needle withdrawal. No patient required conversion to general anesthesia, six patients required midazolam for anxiety and six patients required phenylephrine and atropine for hypotension and bradycardia, recovery was uneventful and without sequelae. The two groups were comparable with respect to gender, age, weight, height, body mass index, ASA classification, preoperative oxygen saturation and preoperative respiratory rate and operative time.

CONCLUSION

This preliminary study has shown that segmental thoracic spinal anesthesia can be used successfully and effectively for open surgeries for abdominal malignancies by experienced anesthetists. It showed shorter postanesthesia care unit stay, better postoperative pain relief and patient satisfaction than general anesthesia.

The use of thiopentone/propofol admixture for laryngeal mask airway insertion

An admixture of thiopentone and propofol was evaluated against propofol for laryngeal mask airway (LMA) insertion. Eighty-one ASA 1 and 2 18- to 65-year-old patients, premedicated with 7.5 mg midazolam orally were assigned randomly to receive either propofol 1% or an admixture of thiopentone and propofol (1.25% and 0.5% respectively), both at a dose of 0.25 ml x kg(-1). Satisfactory conditions for insertion were achieved with the admixture, which was comparable to propofol (73% vs 85%, P>0.05). There was no statistical difference in the incidence or severity of gagging, coughing, inadequate jaw relaxation and laryngospasm. The incidence of hypotension was lower in the admixture group (51% vs 78%, P=0.02). The duration of apnoea was not different between the admixture and propofol group (mean 103s vs 109s respectively, P>0.05). We conclude that thiopentone/propofol admixture can be a suitable alternative to propofol for LMA insertion, producing less hypotension while allowing cost savings of up to 45%. An admixture of thiopentone and propofol (1.25% and 0.5% respectively) can produce suitable conditions compared to propofol 1%, for laryngeal mask insertion. In addition to cost containment, the admixture also produces less hypotension.

The use of propofol for its antiemetic effect: a survey of clinical practice in the United States

STUDY OBJECTIVES

To investigate the use of propofol by anesthesiologists for its antiemetic effect and to compare our findings with published evidence.

DESIGN

Anonymous survey of U.S. anesthesiologists.

SETTING

American Society of Anesthesiologists' annual meeting.

MEASUREMENTS AND MAIN RESULTS

One hundred fifty anesthesiologists were surveyed on how they use propofol to achieve an antiemetic effect. A large majority (84%) of the anesthesiologists surveyed stated they used propofol for its antiemetic effect: 63% of those used propofol for induction only for cases lasting <1 h to achieve an antiemetic effect. In addition 37% used a "sandwich" technique, using propofol at the beginning and end of a case for a similar purpose. There is evidence that the antiemetic effect of propofol is associated with a defined plasma concentration range; mean, 343 ng/mL (10-90% confidence intervals [CI] 200-600 ng/mL). Simulation data demonstrated that after propofol 2 mg/kg, its concentration will drop below 350 ng/mL at 32 min. After 2 mg/kg and 20 mg within 10 min of the end of surgery, its concentration will drop below 350 ng/mL by 7 min after the 20 mg bolus dose. This finding suggests that the plasma concentrations of propofol, when used in these cases, will be below the effective range of antiemetic effect.

CONCLUSIONS

Many anesthesiologists used propofol for its antiemetic effect. There is strong evidence for its antiemetic efficacy after anesthesia maintained by a propofol infusion and also for its use in the postanesthesia care unit (PACU). However, there is little evidence to support its use purely at induction of anesthesia or as part of a "sandwich" technique in an attempt to reduce postoperative nausea and vomiting. This is especially true in cases lasting longer than a few minutes.

Propofol-thiopentone admixture: recovery characteristics

We have investigated, in a prospective double-blind study, recovery from anaesthesia induced by two admixtures of propofol and thiopentone and compared it with a third group of patients who received propofol and lignocaine. Ninety unpremedicated ASA 1 or 2 patients scheduled for elective gynaecological laparoscopy as a daycase procedure were randomly allocated to receive one of three different mixtures for induction of anaesthesia as part of a standardized anaesthetic: Group P50: propofol 1% 10 ml/thiopentone 2.5% 10 ml, Group P75: propofol 1% 15 ml/thiopentone 2.5% 5 ml, Group P100: propofol 1% 20 ml/lignocaine 1% 4 ml. Recovery from anaesthesia was assessed for up to four hours post-induction by critical flicker fusion threshold and best post-box toy completion time. Comparison was made with preoperative baseline performance. There was no significant difference in postoperative recovery between the three groups with either assessment but no group returned to their mean preoperative performance levels within the first four hours post-induction. Nor was there any difference between the groups with respect to postoperative analgesia or anti-emetic administration. Utilizing the most sensitive end-point, a sample of nearly 1000 patients in each group would be required to confirm the observed difference with a power of 0.8 based on the data from this study. In comparison with lignocaine, the addition of thiopentone to propofol does not delay recovery from anaesthesia and does not increase postoperative analgesic or anti-emetic requirements.

Development and psychometric testing of a quality of recovery score after general anesthesia and surgery in adults

A variety of methods have been used to quantify aspects of recovery after anesthesia. Most are narrowly focused, are not patient-rated, and have not been validated. We therefore set out to develop a patient-rated quality of recovery score. We constructed a 61-item questionnaire that asked individuals (patients and relatives, medical and nursing staff; total n = 136) to rate various postoperative items describing features a patient may experience postoperatively. The most highly ranked items were included in a final nine-point index score, which we called the "QoR Score." We then studied two cohorts of surgical patients (n = 449). There was good convergent validity between the QoR Score and the visual analog scale score (rho = 0.55, P < 0.0001). Discriminant construct validity was supported by comparing resultant QoR Scores in patients undergoing day-stay, minor, and major surgery (P = 0.008), as well as a negative correlation with duration of hospital stay (rho = -0.20, P < 0.0001), and, using multivariate regression, demonstrating a significant negative relationship between QoR Score and female gender (P = 0.048) and older age (P = 0.041). There was also good interrater agreement (rho = 0.55, P < 0.0001), test-retest reliability (median rho = 0.61, P < 0.0001), and internal consistency (alpha = 0.57 and 0.90, P < 0.0001). There was a significant difference between the groups of patients recovering from major and minor surgery (P < 0.001). This study demonstrates that the QoR Score has good validity, reliability, and clinical acceptability in patients undergoing many types of surgery.

IMPLICATIONS

We set out to develop a patient-rated quality of recovery score (QoR) that could be used both as a measure of outcome in perioperative trials and for clinical audit. We first surveyed patients and staff to identify important aspects of recovery, then developed a nine-point QoR Score. This was then compared with other measures of postoperative outcome. We found that the QoR Score is a useful measure of recovery after anesthesia and surgery.

Propofol and thiopental in a 1:1 volume mixture is chemically stable

Propofol and thiopental have been used clinically in combination for induction of anesthesia. Studies suggest that this mixture has synergistic activity, recovery characteristics similar to propofol alone, and bactericidal effects on multiple organisms. It may therefore be both clinically useful and cost-effective. In this study, we examined the chemical stability of this mixture. We used high-performance liquid chromatography to quantify the concentration of both propofol and thiopental in a given sample. This technique allows the detection of loss in total drug mass and of the appearance of breakdown products resulting from drug interaction. Ten samples of a 1:1 mixture by volume were prepared and assayed at Time 0 and Days 1, 3, and 7. Half the samples were incubated at 23 degrees C and the rest were stored at 4 degrees C. Other mixtures were assayed before and after filtration at Time 0 and Days 1 and 7 after storage at 23 degrees C. The assay was able to measure accurately the quantity of drug present in the samples. There was no significant decrease in the quantities of either propofol or thiopental in the mixture over the 7-day period. We conclude that the 1:1 volume mixture of propofol and thiopental is chemically stable for 1 wk at room temperature.

IMPLICATIONS

A mixture of propofol and thiopental has been used to induce anesthesia. We investigated the chemical stability of this mixture using high-performance liquid chromatography and found it to be stable for at least 24 h.

Growth of microorganisms in propofol, thiopental, and a 1:1 mixture of propofol and thiopental

To assess and compare the growth of four microorganisms in solutions of intravenous anesthetics, known quanta of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans were inoculated into propofol, thiopental, a 1:1 mixture of propofol and thiopental, and normal saline. All microorganisms were taken from standard stock cultures and incubated for 24 h (48 h for C. albicans). Growth of microorganism in each drug was compared by counting the number of colony forming units (CFUs) grown from a subculture of each inoculated anesthetic at 0, 3, 6, 12, and 24 h. The study shows that propofol strongly supports the growth of E. coli and C. albicans but is bacteriostatic toward S. aureus and weakly bactericidal toward P. aeruginosa. In contrast, both thiopental and the 1:1 mixture of propofol and thiopental behaved differently, exhibiting markedly bactericidal properties toward E. coli, S. aureus, and P. aeruginosa and a bacteriostatic effect on C. albicans. This finding supports recommendations that a strict aseptic technique should be used when handling propofol and that the contents of an ampoule should be used within 6 h of aspirating. The measured high pH of both thiopental and the 1:1 mixture of propofol and thiopental compared to propofol alone suggests pH to be a major factor in determining whether a given drug will support microbial growth.