Lessons learned from a randomised controlled study of perioperative beta blockade in high risk patients undergoing emergency surgery.

BACKGROUND: Perioperative beta blockade has been shown to reduce mortality after major elective surgery. The aim of this study was to determine whether it could reduce the rate of death and morbidity from cardiac complications in high risk patients undergoing emergency surgery. METHODS: Over a one-year interval all patients undergoing major non-elective orthopaedic or general surgery were screened to identify those at high risk of cardiac complications. Consenting, high risk patients were randomly allocated atenolol or placebo for seven days, commencing at anaesthetic induction. Deaths and cardiac complications within 30 days were recorded. RESULTS: Some 2351 patients had an emergency operation; 145 were at high risk and eligible for the study. Of 89 patients approached, 57 initially consented. Only 38 patients, however, completed the study protocol, 19 were withdrawn. Of those who completed the study, 5/20 patients in the placebo group and 3/18 in the treatment group died before hospital discharge (p=0.520). Four others in the placebo group and two in the atenolol group had post-operative non-fatal cardiac events (positive troponin T), p=0.311. CONCLUSIONS: This study of emergency surgery proved more difficult than similar trials in elective surgery. The final study groups were small and there were no significant differences in outcomes. A much larger study is required for a definitive answer.

A comparison of post mortem findings with post hoc estimated clinical diagnoses of patients who die in a United Kingdom intensive care unit.

OBJECTIVE: To determine the accuracy of clinical diagnosis compared to post mortem findings in intensive care patients. DESIGN: A retrospective and blinded review of medical records. SETTING: A nine-bed combined high dependency and intensive care unit in a district general hospital in Gloucester, England. PATIENTS AND PARTICIPANTS: Ninety-seven patients who died on the intensive care unit and subsequently underwent post mortem examination. RESULTS: Suspected cause of death and main clinical diagnoses were determined and compared with findings at post mortem examination. All patients in whom a discrepancy was found had their cases reviewed to determine the significance of the discrepancy using the Goldman classification of post mortem discrepancies. Between June 1996 and May 1999 there were 1718 admissions with 252 deaths (14.7%), where 102 post mortem examinations were performed (40.5%). Five patients were not studied. Of the 97 patients, 4 (4.1%) had Goldman I discrepancies and 19 (19.6%) had Goldman II discrepancies. Complete agreement between pre and post mortem diagnosis was found in 74 (76.3%). Discrepancies fell into four main groups; unrecognised haemorrhage (7 patients), myocardial infarction (5), thromboembolic disease (5) and infectious complications (4). CONCLUSIONS: This study reveals that in an intensive care unit important diagnostic discrepancies were found in 19.6% of patients who underwent a post mortem examination. In a fifth of these (4.1%), survival may have been adversely affected. Haemorrhage was the most commonly missed diagnosis. Despite technological advances in intensive care medicine the post mortem examination continues to have an important role in auditing clinical practice and diagnostic performance.

Haemodynamic effects of tracheally administered adrenaline in anaesthetised patients.

Ten patients undergoing arterial surgery in the leg received a combined general anaesthetic, which included muscle relaxation and intubation of the trachea, and a regional anaesthetic using a lumbar extradural catheter. The radial arterial pressure was measured. Adrenaline 0.1 micrograms.kg-1 was administered intravenously and the heart rate, arterial pressure and oxygen saturation were recorded every 15 s for 10 min. Adrenaline in 5 ml of saline was given into the trachea at 10 min intervals. The first was saline only, and successive injections contained 0.5 micrograms.kg-1, 1 microgram.kg-1, 2 micrograms.kg-1, and 3 micrograms.kg-1 of adrenaline. The mean maximum rise in systolic arterial pressure after adrenaline given intravenously was 30 (SD 11) mmHg, and 15 (SD 16) mmHg after the maximum dose of adrenaline given into the trachea (p < 0.05). The mean systolic arterial pressure was significantly increased between 45 s and 4.5 min after the adrenaline given intravenously, and 2 min after adrenaline given into the trachea. Of seven patients who received adrenaline 3 micrograms.kg-1 into the trachea, six had no noticeable effect and in the other patient, the increase in arterial pressure was less than 90% of the maximum rise after the adrenaline. We conclude that adrenaline given into the trachea is unreliable in humans with very large doses necessary in some patients to produce a clinically useful haemodynamic effect.

A survey of airway management during induction of general anaesthesia in obstetrics: are the recommendations in the confidential enquiries into maternal deaths being implemented?

Recommendations were made in the last two triennial reports on maternal deaths regarding airway management prior to obstetric general anaesthesia. Forty-four hospitals were surveyed to determine departmental practice. Our survey suggests that obstetric anaesthetic practice varies widely between departments and several of the recommendations in the above reports have yet to be implemented.

Comparison of i.v. and intra-tracheal administration of adrenaline.

Adrenaline is the single most important therapeutic agent used in advanced cardiac life support (ACLS). Ideally it should be given into a large central vein but the European Resuscitation Council, the American Heart Association and the Resuscitation Council (U.K.) advise that adrenaline may be given into the trachea if i.v. access is not available. We have studied the effects of intra-tracheal and i.v. adrenaline in 16 patients undergoing mechanical ventilation. Log dose-response curves were constructed for systolic arterial pressure and heart rate responses. Intra-tracheal doses of adrenaline up to 10 micrograms kg-1, approximately one-third of that recommended for resuscitation, had no effect on arterial pressure or heart rate, whereas adrenaline 0.1 microgram kg-1 i.v. produced a mean increase in systolic pressure of 24 mm Hg. The intra-tracheal doses recommended for resuscitation (2-3 mg) are likely to be ineffective and consideration should be given to abandoning the tracheal route for adrenaline in ACLS.

Overpressure isoflurane at caesarean section: a study of arterial isoflurane concentrations.

In this study we have measured arterial concentrations of isoflurane obtained during Caesarean section in two groups of patients. Patients in group 1 received 1% isoflurane throughout operation, whilst those in group 2 received 2% isoflurane for the first 5 min, 1.5% for the next 5 min and 0.8% thereafter. We found that arterial isoflurane concentrations were significantly greater in group 2 than in group 1 (ANOVA, P < 0.05). Isoflurane concentrations greater than 30 micrograms ml-1 were achieved rapidly in most patients in both groups, but there was a large scatter of results. The isoflurane concentration at which awareness or recall may occur is not known, but an "overpressure" technique as described for patients in group 2 may result in fewer patients being at risk of awareness.

Haemodynamic effects of tracheal compared with intravenous adrenaline.

If intravenous access is not available during cardiopulmonary resuscitation, tracheal administration of adrenaline 0.02 mg/kg, twice the intravenous dose, is recommended. In a randomised crossover study we investigated the haemodynamic effects of low doses of tracheal versus intravenous adrenaline. 12 anaesthetised patients having a hip replaced received one dose of adrenaline intravenously (0.1 microgram/kg) and the other tracheally (0.5 microgram/kg). There was a mean increase in systolic arterial pressure of 40.5 mm Hg (range 16-81) after the intravenous injection, with little effect on heart rate. Tracheal adrenaline had no effect on arterial pressure or heart rate. Thus low doses of tracheal adrenaline have no haemodynamic effects. We believe that the recommended tracheal dose of twice the intravenous dose is likely to be ineffective for the treatment of cardiac arrest. Animal studies suggest that a tracheal dose at least ten times the intravenous dose is required.

Caudal blockade for postoperative analgesia: a useful adjunct to intramuscular opiates following emergency lower leg orthopaedic surgery.

The efficacy of a single caudal epidural injection of bupivacaine 20 ml 0.5% following emergency orthopaedic surgery to the lower leg and ankle was investigated. Forty adult patients were studied, randomised to either the caudal or control group. The mean 24 hour postoperative papaveretum consumption was significantly reduced in the caudal group. Analogue pain scores as assessed in a double-blind manner were also significantly reduced in this group. The duration of analgesia after caudal blockade was approximately eight hours as estimated by the average time to the first dose of papaveretum. Our study demonstrates that caudal blockade represents an effective adjunct to intramuscular opiates following this type of surgery.

The Extensometer. Potential applications in anaesthesia and intensive care.

The Extensometer is a new device capable of continuous accurate measurement of length over convex surfaces with a rapid response rate. This makes it a powerful research tool and a useful clinical instrument, particularly in the field of respiratory monitoring. This paper describes the principles behind the device. The linearity of its response was demonstrated in laboratory tests and its ability to quantify abdominal and chest wall movement was assessed in anaesthetised patients. Potential applications in the field of ventilatory pattern analysis and respiratory monitoring in anaesthesia and intensive care are discussed.

Awake intubation: a new technique.

A 46-year-old male with a known history of difficult intubation presented for elective surgery. It was considered prudent to perform an awake intubation and a size 3 laryngeal mask was introduced under topical anesthesia. A gum elastic bougie was then passed, enabling the laryngeal mask to be removed and a tracheal tube to be inserted.

Experience with the laryngeal mask airway in two hundred patients.

Observations were recorded from two hundred consecutive insertions of the laryngeal mask airway (LMA). They were undertaken by 27 anaesthetists most of whom had no previous experience of its use. A clinically patent airway was obtained in 94% of patients and in the majority of these (76%) the LMA was positioned correctly at the first attempt. There were twelve cases of failed insertion. Nine of these were as a result of an inability to pass the LMA correctly into the hypopharynx while in the remaining three cases complete airway obstruction was reported. The insertion technique was easily acquired and trainee anaesthetists achieved a success rate of 84% for their first five attempts. Success with the LMA was related to experience: anaesthetists who had used the LMA over 15 times had no failures in 67 insertions. Twenty-two patients coughed and six developed mild laryngospasm at insertion. The incidence of postoperative sore throat was 8%.

Pain on injection of propofol: the effect of injectate temperature.

A double-blind, randomised clinical study was undertaken to compare the effect of temperature on the incidence and severity of the pain experienced on injection of propofol. The number of patients who experienced pain and the severity of the pain were reduced significantly when propofol was administered at a temperature of 4 degrees C. The efficacy of propofol as an induction agent appeared to remain unaltered.