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Biomedical subjects

J P Barker

Publications and source records attributed to J P Barker.

14 recordsLinked to original sources
PubMed1997

Anaesthetic pollution. Potential sources, their identification and control.

Anaesthetic gases escape into the ambient air mainly from the anaesthetic breathing system but there are many other important sources of anaesthetic pollution. These include the filling of vaporisers, inhalational induction techniques, leaks around the patient's face mask, leaks from monitoring equipment and loose-fitting or perishing equipment. The control of substances hazardous to health (COSHH) regulations together with the recent implementation of the occupational exposure standards (OES) for anaesthetic gases require that any risk to health workers from anaesthetic exposure be assessed, control measures implemented, the environment monitored and OES not exceeded. The installation of costly scavenging equipment is believed to have reduced the levels of pollution in operating theatres, but several independent reports suggest that their use has not been wholly effective. Many sources of pollution remote from scavenging equipment may be responsible for the ineffective control of anaesthetic pollution. During an initial COSHH assessment in our hospital, using an infra-red analyser specifically designed for leak testing and background monitoring, we have identified several controllable sources of pollution. These included leaks from an ill-fitting face mask, loose connections in the anaesthetic breathing system, leaks from the laryngeal mask at the end of the operation and a leak of more than 5400 ppm N2O was found near the unscavenged gas outlet at the back of the multigas monitor. Leak testing, using infra-red analysers with their rapid response, has been recommended as an important aid in the identification of hidden sources of pollution, most of which we believe are amenable to control and remedy.

Air Pollutants, Occupational↗
PubMed1996

Postoperative morbidity following cataract surgery. A comparison of local and general anaesthesia.

Two hundred and thirty-one patients were questioned the day following their cataract surgery to ascertain the incidence of postoperative morbidity. One hundred and nineteen patients received local anaesthesia (LA) and 112 received general anaesthesia (GA). There was a significant difference in the incidence of nausea (21% in GA group, 3% in LA group, p < 0.01), sore throat (41% GA group, 3% LA group, p < 0.01), and bruising of the eye (15% GA group, 39% LA group, p < 0.01). There was no significant difference in the incidence of vomiting, headache, double vision, the severity of postoperative pain, or the need for analgesia. The time before the patients drank and ate postoperatively was significantly shorter in the local anaesthetic group (1.3 h and 1.8 h LA group, 4.1 h and 6.7 h GA group respectively, p < 0.01).

Aged↗
PubMed1995

Metabolic control of non-insulin-dependent diabetic patients undergoing cataract surgery: comparison of local and general anaesthesia.

We studied 40 elderly patients undergoing cataract surgery. Ten non-insulin-dependent diabetes mellitus (NIDDM) patients received standardized general anaesthesia, 10 NIDDM patients received local anaesthesia using retrobulbar block, 10 non-diabetic control patients received general anaesthesia and 10 non-diabetic controls received retrobulbar block. We measured sequential changes in blood glucose, lactate and beta-hydroxybutyrate, serum cortisol and insulin, and plasma non-esterified fatty acid concentrations until 4 h after operation. The results showed that in both general anaesthesia groups, NIDDM and control, blood glucose and serum cortisol concentrations increased significantly during surgery, before returning to normal by 4 h after operation; in both local anaesthesia groups, glucose and cortisol concentrations changed little during surgery. Serum insulin concentrations increased 30 min after operation to coincide with the peak of the glucose increase in the non-diabetic patients who received general anaesthesia, but no insulin response was seen in the diabetic general anaesthesia patients. Blood glucose and insulin concentrations increased in patients who received local anaesthesia (NIDDM and controls) when they ate after operation. The results show that cataract surgery under local anaesthesia provides improved metabolic control for the diabetic patient. Its use maintains glucose homeostasis, prevents the increases in cortisol and glucose which are seen under general anaesthesia and obviates the need for postoperative starvation.

Aged↗
PubMed1994

Retrobulbar block fails to prevent an increase in serum cortisol concentration on emergence from anaesthesia after cataract surgery.

We have studied 30 elderly patients undergoing cataract surgery, allocated randomly to receive general anesthesia, local anaesthesia by retrobulbar block or general anaesthesia combined with retrobulbar block given after induction. Retrobulbar block alone prevented the increases in circulating cortisol and glucose values which occurred in those patients receiving general anaesthesia alone. Retrobulbar block given after induction of general anaesthesia, however, suppressed the cortisol and glucose response during surgery, but did not prevent a marked increase in cortisol concentrations during the immediate postoperative period. The results suggest a hormonal response to emergence from anaesthesia which has hitherto been masked by the stress response to surgery itself.

Aged↗
PubMed1993

The metabolic and hormonal response to cataract surgery. A comparison between retrobulbar and peribulbar blockade.

We studied the metabolic and hormonal responses of 30 elderly patients undergoing routine cataract surgery who were allocated randomly to receive either general anaesthesia, or local anaesthesia by means of either retrobulbar or peribulbar blockade. Both forms of local anaesthesia successfully prevented the increases in circulating cortisol and glucose concentrations seen in those patients who received general anaesthesia, there being no significant differences between retrobulbar and peribulbar blockade. The results show that the newer, and now more commonly performed peribulbar block, confers the same metabolic and hormonal stability as seen with the more traditional retrobulbar block.

Aged↗
PubMed1991

Plasma catecholamine response to cataract surgery: a comparison between general and local anaesthesia.

We studied the plasma catecholamine, plasma glucose and cardiovascular responses to cataract surgery in 20 elderly patients allocated randomly to receive either general anaesthesia or local anaesthesia by retrobulbar block. Local anaesthesia prevented the increase in plasma noradrenaline, adrenaline and glucose concentrations found in those patients who received general anaesthesia and also improved cardiovascular stability. The results show the beneficial effects of local anaesthesia in preventing the hormonal, metabolic and cardiovascular changes found when cataract surgery is conducted under general anaesthesia.

Aged↗
PubMed1990

Local analgesia prevents the cortisol and glycaemic responses to cataract surgery.

We studied the metabolic and hormonal responses to cataract surgery in 18 elderly patients, allocated randomly to receive either general anaesthesia or local analgesia by means of a retrobulbar block. Local analgesia prevented the increases in circulating cortisol and glucose concentrations found in those patients who received general anaesthesia. The results show that complete afferent sensory block of the operative site inhibited endocrine and metabolic responses to ophthalmic surgery.

Aged↗
PubMed1984

Anaesthetic morbidity following caesarean section under epidural or general anaesthesia.

To find out whether morbidity in the first postoperative week is affected by type of anaesthetic technique, healthy patients who had caesarean sections under epidural anaesthesia were compared with those who were given a general anaesthetic. Epidural anaesthesia was associated with less pain (p less than 0.00001) and discomfort in the immediate postoperative period. By the second day fewer epidural patients had gastrointestinal stasis, pyrexia (p less than 0.05), and coughing (p less than 0.00001). Breastfeeding and mobilisation started earlier. Fewer mothers were coughing (p less than 0.005), had fever (p less than 0.01), or felt tired and depressed (p less than 0.005) by the sixth postoperative day after epidural caesarean section. The epidemiology of anaesthetic morbidity needs to be assessed in other surgical patients.

Anesthesia, Epidural↗
PubMed1983

Circannual changes in immune function.

Adrenocortical activity varies on a circannual basis with increased secretion in the winter and decreased secretion in the summer. One consequence of this variation is a circannual pattern in immune function. Adrenal corticosteroids, especially glucocorticoids, depress cellular immune function and seem to be more effective against T-suppressor cells. Thus, when adrenocortical activity is elevated, T-cell activity is depressed and B-cell activity is elevated. To the extent that T-cell "surveillance" is depressed in winter, there should be increased lymphoproliferative cancer risk during winter and in regions characterized by cold climates. This article presents data which suggest: (1) a winter, adrenal-corticoid induced, depression of T-cell function which is accompanied by elevated B-cell function; (2) elevated serum immunoglobulin levels in the winter; and (3) an inverse relationship between ambient temperature and serum immunoglobulin levels. The circannual pattern in immune function could help explain increased lymphoproliferative cancer risk, as a side effect of immunosuppression therapy during organ transplants, and as a function of latitude.

Adrenal Cortex Hormones↗
PubMed1983

Anaesthesia for caesarean section. A medical audit of junior anaesthetic staff practice.

This survey compared the safety of 261 healthy mothers of whom 170 received extradural and 91 general anaesthesia for Caesarean section. Anaesthetics were conducted in routine hospital practice by six anaesthetic registrars. Failed intubation occurred in one patient, awareness was reported by 12 patients following general anaesthesia and two patients had abnormal reactions to drugs. In contrast, the numerous complications that arose with extradural anaesthesia were less serious and easier to manage. Hypotension occurred in 11 patients, inadequacy of analgesia in 25 patients and a period of unawareness in 16 patients following sedation after delivery. Extradural block for Caesarean section is thus seen as safer than general anaesthesia when performed by the same group of anaesthetic trainees on healthy mothers.

Adult↗