Influence of controlled hypotension versus normotension on amount of blood loss during breast reduction.

SUMMARY: Controlled hypotension employed during surgical procedures results in a beneficial reduction in blood loss during the operation. Breast reduction is a common cosmetic surgical procedure. Yet, in the Netherlands, controlled hypotension is not standard during breast reduction procedures, and in fact is only occasionally employed. Our research aimed to establish a set of guidelines which would outline the application of controlled hypotension during breast reduction surgery. The set up of the study was prospective. The patients were randomised into two groups. In the test group, controlled hypotension with an average of 30% reduction in systolic tension was established during the first operative phase. For the control group, normotension was maintained during the entire procedure. The blood loss in the test group (n=23; mean 318 cc) was reduced by 54.1% compared to control (n=28; mean 598 cc), and this difference was significant. A significant positive correlation was also found between blood loss and total incision time. An overall complication rate of 5.1% was observed; however, there was no significant difference between the two groups. A trend in favour of hypotension does suggest it may also help reduce postoperative complications. Our data indicate that a reduction in blood loss of more than 50% can be achieved by employing controlled hypotension in the first operative phase of breast reduction. A reduction in systolic pressure of 20-25% with the use of nitroprusside is sufficient to achieve this reduced blood loss.

Long-term postoperative cognitive dysfunction in the elderly ISPOCD1 study. ISPOCD investigators. International Study of Post-Operative Cognitive Dysfunction.

BACKGROUND: Long-term postoperative cognitive dysfunction may occur in the elderly. Age may be a risk factor and hypoxaemia and arterial hypotension causative factors. We investigated these hypotheses in an international multicentre study. METHODS: 1218 patients aged at least 60 years completed neuropsychological tests before and 1 week and 3 months after major non-cardiac surgery. We measured oxygen saturation by continuous pulse oximetry before surgery and throughout the day of and the first 3 nights after surgery. We recorded blood pressure every 3 min by oscillometry during the operation and every 15-30 min for the rest of that day and night. We identified postoperative cognitive dysfunction with neuropsychological tests compared with controls recruited from the UK (n=176) and the same countries as study centres (n=145). FINDINGS: Postoperative cognitive dysfunction was present in 266 (25.8% [95% CI 23.1-28.5]) of patients 1 week after surgery and in 94 (9.9% [8.1-12.0]) 3 months after surgery, compared with 3.4% and 2.8%, respectively, of UK controls (p<0.0001 and p=0.0037, respectively). Increasing age and duration of anaesthesia, little education, a second operation, postoperative infections, and respiratory complications were risk factors for early postoperative cognitive dysfunction, but only age was a risk factor for late postoperative cognitive dysfunction. Hypoxaemia and hypotension were not significant risk factors at any time. INTERPRETATION: Our findings have implications for studies of the causes of cognitive decline and, in clinical practice, for the information given to patients before surgery.

Elective orthopedic surgery, a model for the study of cytokine activation and regulation.

Induction and downregulation of cytokine production occurs after contact with various inflammatory stimuli. To elucidate the early events after a physical stressor, we studied these processes in 13 patients undergoing elective total hip replacement surgery. In these patients we followed the plasma concentrations of tumour necrosis factor alpha (TNF), interleukin 1beta (IL-1beta), IL-6 and IL-1 receptor antagonist (IL-1Ra), mRNA for these cytokines in peripheral blood cells (PBCs), and the lipopolysaccharide(LPS)-stimulated ex vivo production of these cytokines in whole blood cultures (WBCs). Plasma TNF and IL-1beta were not affected by the surgical procedure, although IL-1beta mRNA levels in PBCs increased significantly. Plasma IL-6 and IL-1Ra increased from 2 to 3 h post-incision onwards. The LPS-induced ex vivo production in WBCs of TNF, IL-1beta and IL-6 decreased from 2 h post-incision; that of IL-1Ra increased. Downregulation of TNF production was not associated with lower TNF-mRNA suggesting post-transcriptional regulatory processes. In contrast, downregulation of IL-1beta production was associated with significantly lower IL-1beta mRNA, suggesting both post-transcriptional and transcriptional mechanisms. Remarkably, the increase of plasma IL-6 occurred when the IL-6 production ex-vivo in WBCs was maximally downregulated. This suggests that other immunocompetent cells and not PBCs are the source for plasma IL-6 and that the IL-6 production in those other cells might be regulated differentially.

Monitoring during cryosurgery of bone tumors.

BACKGROUND: Cryosurgery is used in orthopaedic oncology as adjuvant treatment after intralesional excision of bone tumors to induce cell death at and beyond the surgical margin. Monitoring freeze/thaw cycles during cryosurgery is beneficial in controlling a cryosurgical procedure and in preventing an unwarranted local extent of the freeze. METHOD: We conducted a study of 15 cryosurgical procedures with the use of a protocolized temperature measuring system wit peroperative graphic visualization. RESULTS: Using a liquid nitrogen spray, intralesional temperatures of -150 degrees C were achieved, which are, according to the literature, associated with cell death. Extralesional temperature measurements showed no sub-zero temperatures of surrounding important tissues. CONCLUSIONS: Temperature recordings in and outside the lesion during cryosurgery in orthopaedic oncology are of importance to monitor the freeze/thaw cycles and are helpful in facilitating an effective cryosurgical procedure and in controlling the extent of the freeze, avoiding local complications.

Venous gas embolism during cryosurgery for bone tumors.

Cryosurgery using liquid nitrogen is a method for treating benign- and low-malignant skeletal tumors. The advantage of preserving the supportive function of bone should be compared to the risk for its complications; postoperative fracture is well known, but less so the occurrence of intraoperative venous gas embolism. This paper describes 17 patients: 2 patients who had serious hemodynamic complications during cryosurgery and a study of 15 patients in whom end-tidal N2 tension was measured in an attempt to investigate the clinical incidence of venous gas embolism during cryosurgery. In the 15 cases analyzed, we did not detect any exhaled N2 during cryosurgery.

Spinal monitoring during vertebral column surgery under continuous alfentanil infusion.

An anaesthetic technique for surgical procedures on the vertebral column is described consisting of a continuous infusion of a short acting opioid, alfentanil, and a muscle relaxant, vecuronium, in combination with positive pressure ventilation using a nitrous oxide/oxygen mixture. It is shown that the two standard forms of spinal monitoring, wake-up testing and somatosensory cortical evoked potentials, can be employed effectively using this anaesthetic technique. Wake-up testing was performed in 23 patients. Average wake-up time was 10 min (SD 3.7 min). Evoked responses suitable for spinal monitoring could be obtained in 60 of 61 patients.

Pharmacokinetics of alfentanil during and after a fixed rate infusion.

Twenty-nine patients (age range 14-81 yr) undergoing orthopaedic surgery received alfentanil 100 micrograms kg-1 given as two i.v. boluses followed by a fixed rate infusion of 1 micrograms kg-1 min-1 for 44-445 min. Additional 1-mg bolus doses of alfentanil were administered as required. Plasma samples were assayed for alfentanil using radioimmunoassay. Pharmacokinetic parameters were estimated by a model-independent approach and by curve-fitting. Regression analysis showed no statistical relationship between T 1/2 beta, Cl or Vd and the duration of the infusion, total dose or body weight. We found no significant correlation between age and T 1/2 beta of alfentanil for patients younger than 40 yr. For patients older than 40 yr, T 1/2 beta increased linearly with age. There was no significant decrease in Cl with age, although the lower values for Cl (100-200 ml min-1) were generally found in subjects older than 60 yr. The present study demonstrated that a 100-micrograms kg-1 loading dose and a 1-micrograms kg-1 min-1 infusion may be appropriate for analgesia in general surgical procedures.

Clinical experience with a fixed rate of alfentanil infusion.

Twenty-seven patients received an alfentanil loading dose of 100 micrograms kg-1 in two 50-micrograms aliquots followed by a fixed rate infusion of 1 microgram kg-1 min-1. At clinical signs of response to surgical stimulus, an alfentanil dose of 1 mg was added. Patients were ventilated with a N2O/O2 mixture. Muscle relaxation was achieved with a vecuronium infusion. No other drugs were given during the procedure. Major orthopaedic or maxillo-facial surgery patients were studied. The duration of infusion was from 2-7 h (mean of 3.9 +/- 1.6 h SD). In 25 of 27 cases the anaesthesia was considered adequate and stable. A mean of two additional doses per patient were needed in 25 patients, with a range of zero to four doses in the group. This study supports the view that after an appropriate loading dose a fixed-rate infusion of alfentanil at 1 microgram kg-1 min-1 can be given for up to 7 h to provide satisfactory stable analgesia without undue post-operative ventilatory depression or prolonged recovery in the majority of cases.

Lack of effects of emulsified propofol ('Diprivan') on vecuronium pharmacodynamics--preliminary results in man.

The possible interaction between vecuronium and propofol or thiopentone has been investigated. Cumulative dose response curves for vecuronium and the pharmacodynamic variables measured were similar with both anaesthetic agents. Patients were intubated following the topical application of lignocaine to the larynx and before the administration of vecuronium. A greater degree of relaxation of the vocal cords was noted in patients anaesthetized with propofol.

Etomidate anaesthesia in patients with cirrhosis of the liver: pharmacokinetic data.

Five patients undergoing endoscopic injection of oesophageal varices were anaesthetised with etomidate 0.2 mg/kg followed by an infusion at a rate of 20 micrograms/kg/minute. Fentanyl 100-200 micrograms was also given intravenously and the patients' lungs were ventilated with oxygen in air. The postinfusion plasma etomidate concentration was described by a three compartment model with a mean half-life of 540 minutes (SEM 66.9) and volume of distribution of 8.9 litres/kg (SEM 0.6). Clearance was 12.7 ml/kg/minute (SEM 2.3). Compared to results in the literature obtained from normal patients, these cirrhotic patients had normal clearance rates, but the distribution volume and elimination half-life were twice as great. This suggests that cirrhotic patients metabolise etomidate normally, but the volume of distribution is doubled, thus resulting in prolonged elimination half-lives.

Nitrous oxide influences pattern EP estimate of visual acuity.

The effect of nitrous oxide (N2O) inhalation on the pattern EP with the onset and disappearance of checkerboard patterns was studied in four healthy volunteers. Checkerboards with checks ranging from 2 to 55 min of arc were presented to subjects sedated at various levels. Under the highest level introduced, 60% N2O, fixation of the pattern was still adequate. The major consistent changes in the pattern onset EP under N2O inhalation are (a) preferential attenuation of the response to small checks and (b) an increase of the response amplitude to large checks. The change in the amplitude versus check-size curve under N2O inhalation restricts the assessment of visual acuity on the basis of the pattern EP. In patients sedated with N2O, EP methods can be used only as a gross indicant of visual acuity.

A pharmacodynamic model for pancuronium.

It has been demonstrated that a simple two-compartment kinetic model may account for the changes in plasma concentration of pancuronium after i.v. administration. However, it can be shown that this simple model does not account satisfactory for the observed changes in muscle twitch response. By the addition of a receptor (biophase) compartment, twitch response can be reconciled with model behavior and the characteristics resemble those predicted by animal studies. The complete model is applied to the problem of total renal failure, and shows that patients with this condition are likely to be marginally resistant to small doses of pancuronium, with a normal rate of recovery. However, larger doses are likely to result in delayed recovery, the duration of effect increasing in a dose-dependent manner.