Circulatory arrest in late pregnancy: caesarean section a vital decision for both mother and child.

Circulatory arrest during pregnancy is extremely rare and there should be a well-planned strategy for its management in all hospitals. To consider the priority of the mother's life over the child's and an unwarranted pre-term delivery may lead to hesitancy and uncertainty and jeopardize both of them. In these situations, speed is a priority. Cardiopulmonary resuscitation should commence immediately. The anaesthesiologist should be well aware of the possible advantage of a caesarean section. Even if the obstetrician is responsible for the decision to perform the operation, the anaesthesiologist should strongly support the action. An 'emergency caesarean kit' with the essential surgical instruments should be immediately available in every labour ward and emergency department.

Reduction in the incidence of awareness using BIS monitoring.

BACKGROUND: Explicit recall (ER) is evident in approximately 0.2% of patients given general anaesthesia including muscle relaxants. This prospective study was performed to evaluate if cerebral monitoring using BIS to guide the conduction of anaesthesia could reduce this incidence significantly. PATIENTS AND METHODS: A prospective cohort of 4945 consecutive surgical patients requiring muscle relaxants and/or intubation were monitored with BIS and subsequently interviewed for ER on three occasions. BIS values between 40 and 60 were recommended. The results from the BIS-monitored group of patients was compared with a historical group of 7826 similar cases in a previous study when no cerebral monitoring was used. RESULTS: Two patients in the BIS-monitored group, 0.04%, had ER as compared with 0.18% in the control group (P < 0.038). Both BIS-monitored patients with ER were aware during intubation when they had high BIS values (> 60) for 4 min and more than 10 min, respectively. However, periods with high BIS = 4 min were also evident in other patients with no ER. Episodes with high BIS, 4 min or more, were found in 19% of the monitored patients during induction, and in 8% of cases during maintenance. CONCLUSIONS: The use of BIS monitoring during general anaesthesia requiring endotracheal intubation and/or muscle relaxants was associated with a significantly reduced incidence of awareness as compared with a historical control population.

Victims of awareness.

BACKGROUND: Intraoperative awareness with explicit recall may be followed by long-lasting mental symptoms. However, the average risk for developing mental sequelae after awareness, and the average severity and the duration of symptoms has not previously been illustrated in a consecutive series of awareness cases. METHODS: Nine patients among 18 consecutive, prospectively identified cases of intraoperative awareness with recall could be located after approximately 2 years and agreed to an interview about possible persisting problems. RESULTS: Four of the nine interviewed patients were still severely disabled due to psychiatric/psychological sequelae. All of these patients had experienced anxiety during the period of awareness, but only one had complained about pain. Another three patients had less severe, transient mental symptoms, although they could cope with these in daily life. Two patients denied any sequelae from their awareness episode. CONCLUSIONS: Up to 3 weeks after their unsuccessful anesthetic, repeated information and discussions had been offered. Despite the fact that all patients at that time claimed to be satisfied with this management, and eventually considered no further contacts necessary, this was obviously inaccurate. Therefore, professional psychiatric assessment, treatment and long-term follow-up should constitute standard practice for all patients who have experienced intraoperative awareness.

The use of platelet density and volume measurements to estimate the severity of pre-eclampsia.

BACKGROUND: This study evaluated whether it is possible to estimate the severity of pre-eclampsia through in vitro measurements of platelet and granulocyte parameters. EXPERIMENTAL PROTOCOL: Eighteen pre-eclamptic women in the third-trimester of pregnancy and 11 women in the third-trimester of normal pregnancies were included in the study. Three to 12 months after delivery, 15 patients with pre-eclampsia and all the subjects with normal pregnancies were re-examined. Before delivery, peak platelet density was determined using a specially designed apparatus. Before and 3-12 months after delivery the following were measured: platelet counts, mean platelet volume and neutrophil and monocyte counts. Furthermore, circulating P-selectin, interleukin-6 and myeloperoxidase were determined to estimate platelet, monocyte and granulocyte activities, respectively. RESULTS: Compared to their results after delivery, pre-eclamptic females demonstrated lower platelet counts (P < 0.001) and raised mean platelet volumes (P < 0.01). Both pre-eclamptic women (P < 0.01) and normal pregnancies (P < 0.05) demonstrated elevated soluble P-selectin at pregnancy. Then pre-eclamptic women had advanced neutrophil counts (P < 0.01) but normal pregnancies showed a similar phenomenon (P < 0.001). Interleukin-6 remained normal during pregnancy. Plasma myeloperoxidase levels were lower both in pre-eclampsia (P < 0.05) and in normal pregnancies (P < 0.001). In pre-eclampsia elevated blood pressure was related to higher mean platelet volumes (P < 0.05). Furthermore, a group of pre-eclamptic females whose platelets had disturbed density distribution displayed elevated mean platelet volumes (P < 0.01). CONCLUSIONS: The present work demonstrates considerable platelet alterations in pre-eclampsia. We failed to show granulocyte involvement in the pathogenesis of the disease. Severe pre-eclampsia is related to elevated mean platelet volumes. The latter parameter is associated with disturbed density distribution. It appears possible to estimate disease severity from measurements of platelet density and volume.

Awareness during anaesthesia: a prospective case study.

BACKGROUND: Patients who are given general anaesthesia are not guaranteed to remain unconscious during surgery. Knowledge about the effectiveness of current protective measures is scarce, as is our understanding of patients' responses to this complication. We did a prospective case study to assess conscious awareness during anaesthesia. METHODS: 11785 patients who had undergone general anaesthesia were interviewed for awareness on three occasions: before they left the post-anaesthesia care unit, and 1-3 days and 7-14 days after the operation. FINDINGS: We identified 18 cases of awareness and one case of inadvertent muscle blockade that had occurred before unconsciousness. Incidence of awareness was 0.18% in cases in which neuromuscular blocking drugs were used, and 0.10% in the absence of such drugs. 17 cases of awareness were identified at the final interview, but no more than 11 would have been detected if an interview had been done only when the patients left the post-anaesthesia care unit. Four non-paralysed patients recalled intraoperative events, but none had anxiety during wakefulness or had delayed neurotic symptoms. This finding contrasts with anaesthesia with muscle relaxants, during which 11 of 14 patients had pain, anxiety, or delayed neurotic symptoms. After repeated discussion and information, the delayed neurotic symptoms resolved within 3 weeks in all patients. Analysis of individual cases suggests that a reduced incidence of recall of intraoperative events would not be achieved by monitoring of end-tidal anaesthetic gas concentration or by more frequent use of benzodiazepines. INTERPRETATION: The inability to prevent awareness by conventional measures may advocate monitoring of cerebral activity by neurophysiological techniques. However, the sensitivity of such techniques is not known, and in the light of our findings, at least 861 patients would need to be monitored to avoid one patient from suffering due to awareness during relaxant anaesthesia.

Advances in pulse oximetry.

The interaction between light and tissue is the basis of pulse oximetry. This review focuses on the recent development of pulse oximetry, with special emphasis on the reflection oximetry utilized in fetal and cerebral oximetry.

The effects of midazolam and flumazenil on psychomotor function.

STUDY OBJECTIVE: To determine the effects of midazolam and its antagonism with flumazenil on psychomotor function as assessed by the perceptive accuracy test (PAT) and choice reaction time (CRT). DESIGN: Double-blind, cross-over, randomized, placebo-controlled study. SETTING: Department of Anaesthesiology, University Hospital, Linköping, Sweden. SUBJECTS: 11 healthy volunteers (6 females, 5 males, mean age 32 years). INTERVENTIONS: Midazolam 0.1 mg/kg (Group MH), midazolam 0.035 mg/kg (Group ML), or placebo (Group PL) were injected intravenously (IV) in a cross-over design. Flumazenil 0.5 mg was injected after 60 minutes. Plasma concentrations of midazolam were measured at 3, 30, 60 and 75 minutes. MEASUREMENTS AND MAIN RESULTS: Baseline values were first obtained on psychomotor tests including the PAT and CRT. These tests were then repeated 30 and 60 minutes after the IV injection of midazolam or placebo, and repeated 15 and 30 minutes following the injection of flumazenil. A dose-dependent effect of midazolam was seen on the PAT and CRT. Flumazenil completely reversed the psychomotor effects of midazolam in Group ML at 60 minutes but not in Group MH, and this action was clearly detected by the PAT. Psychomotor tests had returned to baseline values when the plasma concentration of midazolam was below 33 ng/ml. A marked inter-individual variation was seen on the PAT, CRT, and in the correlation between the plasma concentration and the results on the PAT. CONCLUSIONS: There was a dose-dependent deterioration in psychomotor performance in subjects given midazolam. The PAT was sensitive in the detection of these residual effects, but a large inter-individual variation in the psychomotor effects of midazolam was evident that could be due to pharmacodynamic and pharmacokinetic variability between individuals. Flumazenil in a dose of 0.5 mg IV completely reversed the effects of low-dose, but not high-dose, midazolam.

Anaesthesia for day-care arthroscopy. A comparison between desflurane and isoflurane.

A study was undertaken to compare desflurane- and isoflurane-based anaesthesia in patients undergoing day-care arthroscopic surgery. Anaesthesia was induced with propofol 2-3 mg.kg-1 and a laryngeal mask airway was inserted after loss of the eyelash reflex. Patients were then randomly divided into two groups to receive maintenance anaesthesia with either isoflurane or desflurane delivered in oxygen and nitrous oxide. Alfentanil was used as the analgesic during the operation. Early recovery was assessed by measurement of the times to eye opening, extubation and ability to give a date of birth. Psychomotor recovery was assessed by performance on the finger tapping and perceptive accuracy tests. Mood was evaluated using visual analogue mood scores and the mood adjective checklist. Discharge times were also measured. Early recovery was significantly quicker following desflurane anaesthesia but no differences between the groups were found in psychomotor tests. The mood adjective checklist showed that patients in the isoflurane group had a greater total mood score and were more calm than those in the desflurane group; this was particularly evident 2 h after anaesthesia. The discharge times were similar for the two groups. Desflurane is a satisfactory alternative to isoflurane for day care anaesthesia.

Assessment of recovery following day-case arthroscopy. A comparison between propofol and isoflurane-based anaesthesia.

Fifty healthy patients, aged 15-45 years, undergoing day-case arthroscopy, participated in a study to assess aspects of recovery and mood. Psychomotor tests, including the p-deletion test and the Trieger dot test, were performed pre-operatively and mood was measured using the mood adjective checklist. Anaesthesia in all patients was induced with propofol and a laryngeal mask airway was inserted immediately. All patients received alfentanil as the intra-operative analgesic. The patients were randomly allocated to receive one of two different regimens for maintenance of anaesthesia: propofol group--maintenance with an infusion of propofol 10 mg.kg-1.h-1 for 15 min followed by 6 mg.kg-1.h-1 and nitrous oxide and oxygen (bolus doses of propofol were given if anaesthesia was deemed to be light); isoflurane group--maintenance with isoflurane (inspired concentration 0.5-2.0%) in nitrous oxide and oxygen. Postoperatively, psychomotor tests were repeated every 30 min and mood was measured after 2 h and 24 h. Psychomotor recovery was quicker in the isoflurane group than the propofol group and had returned to baseline values in the isoflurane group by 60 min. The time to discharge was similar in both groups as was the incidence of side effects. There was no difference in mood scores between the groups either at the time of discharge or at 24 h. We conclude that psychomotor recovery is somewhat quicker when isoflurane-based anaesthesia is used for day-case arthroscopy, but other factors, including time to awakening, mood and time to discharge are similar for both techniques.

Pulse oximetry--clinical implications and recent technical developments.

The pulse oximeter has been shown to be a reliable monitor of arterial oxygen saturation and has therefore been recommended as mandatory monitoring for patients during anaesthesia and intensive care. In 1989 two review articles on pulse oximetry were published (1, 2) and two years ago Severinghaus and Kelleher summarized the literature between 1989 and October 1991 (3). Our aim is to focus the discussion on technical aspects and applications of pulse oximetry with special attention centered on recent developments. This review is consequently an update on pulse oximetry since the end of 1991, and the first on technically-based publications in the two last decades.

Changes in end-tidal carbon dioxide during gynecologic laparoscopy: spontaneous versus controlled ventilation.

STUDY OBJECTIVE: To study the changes in PETCO2 during spontaneous and controlled ventilation in patients undergoing gynecologic laparoscopy. DESIGN: Randomized, unblinded study. SETTING: Department of Gynecology, University Hospital, Linköping, Sweden; Central Hospital, Norrköping, Sweden. PATIENTS: Forty healthy patients undergoing gynecologic laparoscopy. INTERVENTIONS: Patients were divided into 4 groups: Group 1 breathed spontaneously via an endotracheal tube, while the other three groups underwent controlled ventilation to an initial PETCO2 of 3 kPa (22 mmHg) (Group 2), 4 kPa (30 mmHg) (Group 3), or 5 kPa (37 mmHg) (Group 4). MEASUREMENTS AND MAIN RESULTS: PETCO2 levels were measured at fixed time intervals. Arterial blood gas analyses were done to compare the difference between PETCO2 and PaCO2. In Group 1, PETCO2 increased soon after insufflation and remained above 6 kPa (44 mmHg) throughout the procedure. In Groups 2, 3, and 4, PETCO2 also rose after insufflation, and an initial PETCO2 of 4 kPa (30 mmHg) was ideal, as all PETCO2 values were less than 5.5 kPa (41 mmHg). Occasional episodes of arrhythmia were seen in Group 1. However, no major adverse effects were observed in any of the groups. CONCLUSIONS: In view of the high PETCO2 levels, spontaneous breathing should be avoided during gynecologic laparoscopy, and ventilation to an initial PETCO2 of 4 kPa (30 mmHg) is recommended during controlled ventilation.

Alfentanil or fentanyl during isoflurane-based anaesthesia for day-care knee arthroscopy?

Forty patients agreed to participate in a study to compare whether fentanyl or alfentanil used as analgesic is associated with quicker recovery following anaesthesia for outpatient arthroscopy procedure. Psychomotor tests including choice reaction time (CRT), perceptive accuracy test (PAT) and finger tapping test (FTT) were done prior to induction of anaesthesia with propofol (2-3 mg.kg-1). Patients were then divided into two groups: Group F (fentanyl) received 0.1 mg fentanyl prior to start of surgery and thereafter 0.05 mg every 30 min during the procedure. Group A (alfentanil) received 0.5 mg alfentanil prior to the onset of surgery and 0.25 mg every 15 min thereafter. Anaesthesia was then maintained using isoflurane (0.5-2%) in oxygen and air (FiO2 0.33) during spontaneous respiration with a face mask in a Bain's system. Psychomotor tests were repeated every 45 min postoperatively. Clinical recovery, visual analogue pain intensity score (VAS) and time to discharge home were also assessed by a nurse blind to the method used. Patients in Group A returned to baseline values on the FTT after 90 min while those in Group F did not return to baseline values until 135 min after the end of the operation. Clinical recovery and time to discharge home ("home ready") were also significantly longer in Group F. There was no difference in recovery as seen in the PAT and CRT between the groups. Also, there was no difference in the incidence of side effects and the pain intensity (VAS) scores were similar in the two groups at all time periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Out-patient surgery--a survey of anaesthesia care in a university hospital.

This study was done at the Linköping University Hospital, Sweden, to assess the quality of care given to patients undergoing outpatient anaesthesia. A questionnaire was given to all adult patients (> 15 years old) immediately on admission to the outpatients' surgical ward and the patients were asked to answer all the questions, if necessary with the help of an attending nurse. Another questionnaire was given to the patients in the post-operative ward immediately prior to their being discharged home. Analyses of results indicate that although most patients were satisfied with the care offered at the outpatient surgical unit, 50% requested, but were not given, anxiolytic premedication before the operation. A majority of these were women undergoing gynaecological operations. Twenty per cent of the patients complained of post-operative pain that was poorly managed. Drowsiness (12%), headache (10%), and sore throat (8%) were common complications following general anaesthesia. In contrast, patients who had regional or local anaesthesia had an extremely low incidence of complications. Almost one-third of the patients were discharged without a responsible person accompanying them home and 25% were alone at home during the first 24 hours. Of the patients who went home alone, most either walked, cycled or took the bus, but 4% actually drove home after the operation. In our opinion more stress should be laid on patient information before the operation and better methods to relieve preoperative anxiety should be used whenever indicated.(ABSTRACT TRUNCATED AT 250 WORDS)

Halothane-diethyl ether azeotrope anesthesia under primitive conditions: guidelines for neuromuscular blockade with vecuronium.

The dose-response relationship for vecuronium during anesthesia with the azeotropic mixture of halothane and diethyl ether (HE) (66 ml of halothane mixed with 34 ml of ether in the same bottle)/oxygen was compared with halothane/nitrous oxide/oxygen anesthesia. The HE is not explosive and has preserved many of the advantageous properties of diethyl ether, making it an attractive anesthetic drug under difficult circumstances such as war or civil disaster. If muscular relaxation is needed in military anesthesia, it is essential to use a short- to medium-acting compound that can be stored without refrigeration. Vecuronium bromide fulfills these criteria. The study was conducted on 20 young (mean 24 years, range 18-31), ASA I patients. Using adductor pollicis mechanomyography and a cumulative dose technique, individual dose-response curves for vecuronium were constructed. Care was taken to keep peripheral and core temperatures normal and the times of exposure to inhalational gases equal. The results were analyzed by the log-probit method. During HE anesthesia, ED50 for vecuronium was 22 +/- 2 micrograms kg-1 (mean +/- SE) and ED90 was 49 +/- 8 micrograms kg-1. During halothane/nitrous oxide anesthesia, ED50 for vecuronium was 18 +/- 2 micrograms kg-1 (mean +/- SE) and ED90 was 39 +/- 7 micrograms kg-1. The dose-response relationships for vecuronium were similar during HE anesthesia and halothane/nitrous oxide anesthesia.

Peroperative nitrous oxide does not influence recovery after laparoscopic cholecystectomy.

We have evaluated the effects of nitrous oxide on recovery following laparoscopic cholecystectomy in a prospective, randomised, double-blind study with 42 otherwise healthy patients. All patients received meperidine 1 mg/kg and atropine 6 micrograms/kg im for premedication, and anaesthesia was induced with fentanyl 2 micrograms/kg and thiopental 4-6 mg/kg. Succinylcholine was used for the intubation and muscle relaxation was achieved using vecuronium. Isoflurane with 70% nitrous oxide in oxygen and fentanyl was used for maintenance of anaesthesia in group I (n = 19), and isoflurane in air/oxygen and fentanyl in group II (n = 23). The postoperative ward staff and the surgeon evaluating the postoperative recovery were blinded to the anaesthetic technique. No differences were found in duration of operation and anaesthesia, need for postoperative analgesia or postoperative nausea treated medically. Recovery, judged by the Steward Coma Score, comprehension and collaboration, degree of sedation and orientation in time and space, was similar in the two groups. Postoperative hospital stay was 1 (1-4) day in the nitrous oxide group (median (10-90th percentiles) versus 2 (1-4) days in the air group. The time until patients were recovered, as judged by return to work and normal daily activities, was the same in the two groups: 8 (4-11) days in the nitrous oxide group and 8 (4-11) days in the air group. We conclude that nitrous oxide has no influence on recovery after laparoscopic cholecystectomy.

Maternal respiratory function following normal vaginal delivery.

Forced expiratory volume (FEV(1)) forced vital capacity (FVC), peak expiratory flow (PEF) and maximum expiratory pressure (P(E)max) were measured in 11 healthy women 2, 4, 8, 24, 48 and 72 hours after normal vaginal delivery and repeated after 6-8 weeks. There was a significant (P<0.05) reduction in the P(E)max up to 4 hours after delivery. In contrast, there was no significant reduction in FEV(1) or FVC at any of the time periods, and PEF showed a significant reduction only at 2 hours after delivery. This indicates that P(E)max is a more sensitive measure of respiratory muscle strength and that this is reduced for at least 4 hours after delivery. Any anaesthetic given during this period should take into consideration that the ability to cough effectively may be impaired.

Experimental evaluation of two new sensors for respiratory rate monitoring.

Visual observation was chosen as the reference method for measuring the respiratory rate in ten healthy volunteers. The new fibre-optic and acoustic sensors were simultaneously compared with capnography and transthoracic impedance plethysmography during normoventilation in the respiratory rate range of 6-24 breaths per minute and at a fixed respiratory rate of 13 breaths per minute. In addition a simulation of central apnoea was performed. All the measurements were recorded on an analogue tape recorder and a strip-chart recorder and analysed off line. The analyses of the recordings were performed by a person who was unable to see the monitoring systems. There was no discrepancy in the results of these methods. Each of the methods responded rapidly to an apnoeic event. The new fibre-optic and acoustic sensors correlate well with more traditional methods such as capnography and transthoracic impedance plethysmography for respiratory rate monitoring.

Accuracy of pulse oximetry at various haematocrits and during haemolysis in an in vitro model.

In situations in which it may be impossible and/or unethical to evaluate pulse oximetry in humans, an in vitro model with circulating blood may be a necessity. The main objective was to develop such an in vitro model and, in this model, validate the pulse oximetry technique at various haematocrit levels. The pulsating character of arterial blood flow in a tubing system was simulated by using a specially constructed pressure-regulated roller pump. The tubing system was designed to minimise damage to red blood cells. The pulse oximeter readings (SpO2) were compared with oxygen saturation analyses by a haemoximeter (SaO2). The pulse oximetry readings were recorded at various haematocrit levels and during haemolysis in the SaO2 range 60-100 per cent. At a haematocrit level of 41-44 per cent, there was no correlation between SaO2 and SpO2 readings. After diluting the blood with normal saline to a haematocrit of 10-11 per cent, a good correlation between SaO2 and SpO2 was found. Following haemolysis, the agreement between SaO2 and SpO2 was further improved. Using the developed in vitro model, the results indicate that the accuracy of a pulse oximeter may be dependent on the haematocrit level.