Pre-caesarean section haemoglobin: a worthless investigation.

Haemoglobin concentration is measured routinely before caesarean section in many obstetric units. It is also measured early in the third trimester in order to screen for anaemia. We investigated the hypothesis that when the haemoglobin concentration was normal in the early third trimester, a repeat measurement immediately before surgery at term provided no useful additional information. A total of 106 cases were studied of elective (n = 45) and emergency (n = 61) caesarean sections. In the majority of elective (28 of 45) and emergency (49 of 61) patients, the haemoglobin concentration rose by term. In a minority of elective (14 of 45) and emergency (12 of 61) patients, the haemoglobin concentration fell. The largest fall was by 1.3 g/dl and the lowest term value was 10.1 g/dl. In three elective patients, the concentration did not change. Peri-operative management at term may therefore be guided by the haemoglobin concentration measured early in the third trimester. There appears to be no clinically significant change in haemoglobin during this time and there are physiological changes in the circulation that explain this effect. Discontinuation of routine pre-operative haemoglobin concentration measurement could lead to a significant financial saving.

Comparison of epidural methadone with epidural diamorphine for analgesia following caesarean section.

Analgesia provided by either 5 mg diamorphine, or 5 mg methadone administered by the epidural route during elective caesarean section was compared in 40 women. The median time to further analgesia in the methadone group was 395 min, and 720 min in the diamorphine group, P = 0.0003. Linear analogue scores to assess pain were measured 2-hourly for 12 h, then again at 24 h postoperatively. Pain scores were significantly lower in the diamorphine group at 8 and 10 h. The median cumulative i.m. morphine dose administered during the first 24 h was 20 mg in the methadone group and 0 mg in the diamorphine group (P = 0.0005). Nausea and pruritus were common side effects in both groups. Continuous pulse oximetry data were available for 12 h post-operatively in 15 patients receiving methadone, and in 17 patients receiving diamorphine. One or more episodes of significant desaturation (< 90% for 30 s), occurred in three patients receiving methadone, and in nine patients receiving diamorphine. Desaturation to 90-92% occurred in a further three patients given epidural diamorphine, and in one further patient given epidural methadone.

Ligature versus purse string for surgical stapled anastomoses.

Intraluminal circular stapling in gastrointestinal surgery requires a purse string suture which secures the bowel around the anvil of the head of the stapling gun before firing. An alternative method of securing the bowel around the anvil is described.

Arterial oxygen saturation during induction of anaesthesia and laryngeal mask insertion: prospective evaluation of four techniques.

In a prospective, randomized study of 87 patients, we have compared the incidence of hypoxaemia during induction of anaesthesia with subsequent Laryngeal Mask Airway (LMA) insertion in healthy adults when four different techniques were used: one without supplementary oxygen, and three with supplementary oxygen. Twelve patients did not receive supplementary oxygen before LMA placement, 25 underwent partial denitrogenation by breathing oxygen from the start of injection of the induction agent, 25 underwent formal denitrogenation by breathing oxygen for 3 min, and 25 received five tidal volume breaths of oxygen by face mask using positive pressure immediately after induction of anaesthesia. Anaesthesia was induced with propofol 2.0 mg kg-1 and fentanyl 1 microgram kg-1. Additional propofol was given if required. Arterial oxygen saturation was measured by pulse oximetry. Desaturation occurred in 11 of 12 patients who did not receive supplementary oxygen, and in 19 of 25 patients who received manual ventilation with 100% oxygen after induction of anaesthesia before LMA insertion. Full denitrogenation and partial denitrogenation were equally successful in preventing desaturation. Failure to position the LMA successfully occurred in 3% of patients, and some difficulty was encountered in another 18%.

Amyloid tumour of the breast simulating carcinoma.

A case is presented of a 55-year old woman with longstanding rheumatoid arthritis who presented with a lump in her right breast and a markedly enlarged right axillary lymph node. Carcinoma of the breast with lymphadenopathy was diagnosed clinically, but excisional biopsy revealed an amyloid tumour of the breast and amyloid lymphadenopathy. Amyloid tumour of the breast is an infrequently reported lesion and the association of axillary lymphadenopathy has not been reported before. The literature is reviewed and the need for a tissue diagnosis prior to embarkation on specific therapy is emphasized.

The reliability of rates of glucose appearance in vivo calculated from single tracer injections.

The rate of appearance of unlabelled glucose was calculated from changes in plasma glucose specific radioactivity after a single intravenous injection of labelled glucose and compared with the actual constant infusion rate of unlabelled glucose into an anaesthetized dog with all sources of endogenous glucose production surgically removed. The mean steady-state rate of appearance of unlabelled glucose calculated from the area under the specific radioactivity versus time curve was 7% higher than the actual infusion rate (n = 4), but the difference was not statistically significant. The variability in the rate calculated in this manner was, however, greater than the variability we have reported with rates determined from a primed constant infusion of tracer. Using 15- to 60- or 60- to 120-min specific radioactivity data the mean rate of appearance of glucose, calculated on the assumption of a one-pool model for glucose turnover in vivo, was approximately 60% higher than the actual infusion rate. The results also indicate that it is possible to construct multi-pool models, but it is difficult to equate specific physiological events with the individual terms of the multi-experimental equation which describes the changes in plasma glucose specific radioactivity.

Glucose metabolism in man: responses to intravenous glucose infusion.

We have determined the effect of unlabeled glucose infusions, with and without added insulin, on glucose metabolism in normal male volunteers by means of the simultaneous primed-constant infusion of 6-3H and U-13C-glucose. Glucose kinetics were measured after 90 min of infusion. When steady state had been reached, endogenous glucose production (2.53 +/- .058 mg/kg . min, X +/- SEM) was suppressed at all rates of exogenous glucose tested (1, 2, and 4 mg/kg . min). The absolute degree of suppression was most marked (75%) at the highest rate of infusion, but the greatest degree of suppression, relative to infusion rate, was at the lowest infusion rate. The control of plasma glucose concentration during the glucose infusion was achieved primarily through regulation of endogenous Ra. The rate of uptake of glucose only increased during the 4 mg/kg . min infusion, even though there were significant elevations in the plasma glucose and insulin concentrations during the 2 mg/kg . min infusion as well. The glucose clearance rate increased only when sufficient insulin was infused with the 4 mg/kg . min glucose infusion to control the hyperglycemia that developed if no insulin was administered. Approximately 43% of the infused glucose was directly oxidized when the infusion rate was 1 or 2 mg/kg . min. That value fell to 32% when the infusion rate was increased to 4 mg/kg . min, regardless of whether insulin was infused or not.

Glucose kinetics and responsiveness to insulin in the rat injured by burn.

The are persistent alterations in glucose metabolism in the rat during the first week after a 20 per cent body surface area burn injury. The basal rate of endogenous glucose production is elevated, and it is not suppressed to a normal degree by an exogenous glucose infusion. The hormonre data suggest that increased glucagon levels are responsible for the elevated rate of gluconeogenesis both before and during an exogenous glucose infusion. Basal glucose uptake was also elevated after injury, and there was a normal increment in the glucose metabolic clearance rate during an exogenous glucose infusion. The increase in the glucose metabolic clearance rate relative to the increase in the insulin concentration was equivalent in the burn and control groups of rats. This indicated a normal responsiveness to insulin after injury. Because there was no impairment in the capacity to take up an exogenous glucose infusion, we would question the insulin resistance rationale for administering insulin to patients rendered hyperglycemic by glucose infusion.

Gastric mucosal lesions after burn injury: relationship to H+ back-diffusion and the microcirculation.

Rats were subjected to a 30% body surface area full-thickness burn. Two hours after injury, 93% of animals had gastric mucosal erosions. At 5 hours this increased to 100%, but at 24 and 72 hours, lesions were fewer and less severe. Histologic study suggested that lesions noted at 24 and 72 hours represented erosions formed earlier. No mucosal abnormalities were noted in control rats. A causal relationship between mucosal ischemia and the development of erosions is suggested by the presence of A-V shunts at 2 and 5 hours only. Significant increases in H+ back-diffusion and protein leakage into the gastric lumen at 2 and 5 hours also implicated changed mucosal permeability in the etiology of erosions. The return of H+ back-diffusion to control values at 24 and 72 hours, when lesions were still present, appears to contradict the theory that permeability changes are secondary to erosion formation.

Factors which influenced postoperative complications in patients with ulcerative colitis or Crohn's disease of the colon on corticosteroids.

A retrospective analysis was undertaken of the records of 107 patients with Crohn's disease of the colon or with ulcerative colitis who underwent 162 operations under steroid cover. The study revealed no correlation between steroid dosage and postoperative morbidity or mortality. The incidence of wound dehiscence and incisional hernia compared favourably with the reports of other unselected series of similar patients. Contamination did significantly influence results. Septic complications were more frequent when the operative field was contaminated and both delayed wound healing and mortality were related to this sepsis. A ;clean and dirty' technique was effective in controlling contamination during elective bowel division but preoperative bowel perforation and accidental entry into the lumen of the bowel during dissection were potentially avoidable sources of contamination. Primary healing of the perineal wound after proctocolectomy was seldom achieved in contaminated patients where a drain tube was brought out through the main perineal incision. When perineal sinuses or fistulae followed a proctocolectomy, patients with Crohn's disease had a significantly slower rate of healing than did patients with ulcerative colitis. However, there was no difference in the healing of abdominal wounds in relation to the primary pathology. Even abdominal incisions which were used on more than one occasion healed as well as those which were used for the first time. A prophylactic antibiotic regime of either ampicillin or tetracycline offered little protection against postoperative sepsis. The organisms which caused such infections were often insensitive to the two antibiotics.

Tracer priming the bicarbonate pool.

We have described a technique whereby the time necessary to reach an equilibrium enrichment of expired CO2 during a primed-constant infusion of [U-13C]glucose was shortened from 7 to 8 h to 1 hour or less. We applied the theory of the primed-constant infusion technique to the bicarbonate pool, with the "constant infusion" of labeled carbon dioxide originating from oxidation of the infused [13C]glucose rather than from a labeled infusion of bicarbonate.

The realiability of rates of glucose appearance in vivo calculated from constant tracer infusions.

The rate of appearance of unlabelled glucose was calculated from tracer data and compared with the actual rate of infusion of unlabelled glucose into a anaesthetized dog with all sources of endogenous glucose production surgically removed. The mean steady-state rate of appearance of unlabelled glucose calculated from the equilibrium specific radioactivity was insignificantly higher (0.3%) than the actual rate of infusion of unlabelled glucose (n = 6). During non-steady states, a time-variable volume of distribution of glucose (V) was necessary to predict the rate of appearance of unlabelled glucose correctly from the pool-dependent equation described by Steele [(1959) Ann. N.Y. Acad. Sci. 82, 420--430]. Rapid fluctuations in the rate of appearance of glucose could be predicted reasonably well by using a fixed value of V for 40ml/kg, but by using larger fixed values for V (100--160ml/kg) the rates were inaccurate. The pool-dependent two-radiactive-isotope technique described by Issekutz, Issekutz & Elahi [(1974) Can. J. Physiol. Pharmacol. 52, 215--224] predicted single-step increases in the rate of infusion of glucose reasonably accurately, but the Steele (1959) equation was better at predicting sequential changes in the rate of infusion of unlabelled glucose.

Fallibility of the intravenous glucose tolerance test as a measure of endogenous glucose turnover.

We have used hepatectomized, nephrectomized dogs receiving a constant infusion of unlabeled glucose as well as conscious, unrestrained guinea pigs in order to investigate the calculation of basal glucose kinetics from intravenous glucose tolerance tests (IVGTT). In the dogs, we were not able to determine the known rate of appearance (Ra) or disappearance (Rd) of glucose within 50% of the actual value by means of IVGTT. In the guinea pigs, we found that Ra calculated from IVGTT was 250% higher than Ra determined by means of the validated technique of the primed-constant infusion of 6-3H-glucose in tracer quantities. When live Escherichia coli were infused into the guinea pigs, the isotope-tracer technique revealed a 100% increase in Ra yet Ra appeared to be decreased by 80% when calculated by means of IVGTT. We concluded that basal glucose kinetics cannot be determined reliably from IVGTT, and that in certain pathologic conditions the direction of change in Ra and Rd from the basal state may be incorrectly predicted.