The polio epidemic in Copenhagen in 1952--and how the anaesthetist came out of the operating room.
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Anesthesiology↗
Biomedical subjects
J B Löfström
Publications and source records attributed to J B Löfström.
Influence of intrathecal morphine and naloxone intervention on postoperative ventilatory regulation in elderly patients.
Thirty elderly patients undergoing major hip surgery under spinal analgesia were randomly allocated in a double-blind manner into three groups. The aim was to evaluate the influence of intrathecal morphine and postoperative naloxone infusion on the regulation of ventilation. The Bupivacaine Group received spinal analgesia with 20 mg bupivacaine intrathecally. The Morphine Group received spinal analgesia with 20 mg bupivacaine + 0.3 mg morphine intrathecally. The Naloxone Group received spinal analgesia with 20 mg bupivacaine + 0.3 mg morphine intrathecally + postoperative naloxone infusion intravenously (1 microgram/kg/h over 12 h, 0.25 micrograms/kg/h over the next 12 h). Evaluation of resting ventilation and the ventilatory responses to hypercarbia and hypoxaemia was made on three occasions: before surgery, and 8, and 24 h after the intrathecal injection. Intrathecal morphine had no significant effect on ventilatory regulation in elderly patients undergoing major hip surgery performed under bupivacaine spinal analgesia. Postoperative administration of opioids or sedatives after intrathecal morphine as well as postoperative blood loss associated with a fall in blood pressure appeared to increase the risk of developing respiratory depression. Naloxone infusion seemed to reduce the risk of developing respiratory depression. Furthermore, one third of the elderly had a poor response to hypoxaemia before surgery.
Aged↗
Effect of intradermal injection of saline or a local anaesthetic agent on skin blood flow--a methodological study in man.
The influence of intradermal needle insertion and fluid injection on skin blood flow was investigated using laser Doppler flowmetry. Seventeen healthy, young male volunteers participated. Four test sites on each forearm (volar surface) were used in a randomized, double-blind study. Recordings were made at 20, 40, 60 and in Group III also at 90 min after needle insertion or intradermal injection. In Group I (n = 6) different volumes of saline (0.05, 0.1, 0.2, 0.3 and 0.5 ml) were injected, producing an increase in flow, there being no differences between the various volumes. In Group II (n = 4) needle insertions were made using different needle sizes (20 G, 23 G and 30 G), the larger ones being impractical to use. Increases in flow were seen, and were somewhat higher for the larger needles. Group III (n = 12) was studied regarding the effects of three local anaesthetic agents on skin blood flow (0.1 ml, 30 G needle). Injection of bupivacaine 0.75% produced a marked increase in flow, similar to lidocaine 1% but apparently longer lasting. Bupivacaine 0.25% caused less increase in flow, similar to the flow seen with saline. Injections of ropivacaine 0.75% and 0.25%, i.e. in clinical concentrations, caused a decrease in blood flow, this being most marked after 0.25%, indicating a unique flow-decreasing effect of this new local anaesthetic drug.
Adult↗
The test dose in regional anaesthesia.
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Accident Prevention↗
Vagal and sympathetic activity during spinal analgesia.
Indices of vagal and sympathetic activity were studied in 30 elderly males, to elucidate their possible roles in causing hypotension during spinal analgesia. The technique of spinal analgesia and the regimen of intravenous fluids were standardised. An index of vagal activity was derived from the degree of heart rate variation (successive RR interval change) on ECG recordings. Sympathetic activity was evaluated by changes in the skin conductance (SCR) of 15 patients. Analgesia to pinprick reached a median dermatome level of T5-6 (range T2-T10) by 15 min. Hypotension was correlated with the level of analgesia, and was more likely when spinal analgesia was higher than T5. There was no correlation between vagal activity and the degree of hypotension. The depression of skin conductance responses was not correlated with the degree of hypotension nor with vagal activity. Vagal efferent activity, measured at the heart, does not seem to play a causative role in hypotension occurring during spinal analgesia.
Aged↗
A new method for studying the ventilatory response in patients.
A method for clinical studies of the ventilatory response to carbon dioxide and to hypoxaemia in patients is described. The main parameters with this method are respiratory frequency, tidal volume, minute volume, timing, and drive. The ventilation of volunteers was not affected while breathing air through the designed apparatus. The response to carbon dioxide and to hypoxaemia in volunteers was reproducible and similar to what has previously been described. Our method proved suitable to test the ventilatory responses in patients with varying degrees of impaired ventilation-perfusion ratios and thus also in patients with a low PaO2. Our method has a higher accuracy than earlier methods.
Adult↗
Nerve block in pancreatic pain.
Pain from pancreatic cancer is, in most cases, both severe and debilitating. Large doses of morphine are sometimes not tolerated or accepted by the patient, and are often ineffective. It has been claimed that "coeliac plexus block is the simplest, most effective and least hazardous" means of palliation (49, 59); we think that this is true, and that coeliac plexus block should be considered more often than it is today, and at an earlier stage. Only in rare cases should pain from pancreatitis be treated with a nerve block.
Abdominal Pain↗
[Upper airway obstruction and anesthesia--on warning signals illustrated by some cases reported to the Swedish Medical Responsibility Board].
Upper airway obstruction (e.g., epiglottitis, Ludwig's angina, or laryngeal tumour) can be a serious and life-threatening condition. The patient is asphyxiated, tired and prone to sudden apnoea and/or cardiovascular collapse. In using i.v. anaesthesia and muscle relaxation (e.g., by means of succinylcholine), the anaesthetist is taking a chance, and relying on being able to intubate the patient. Such an approach may lead to the patient's death, however, should the anaesthetist be unable to secure a free airway for artificial ventilation or to intubate the patient. Clinical symptoms are described as is the pathophysiology of upper airway obstruction. Preparatory intubation, while the patient is conscious, would seem to be the safest procedure to use in such cases.
Airway Obstruction↗
Should oxygen be administered after laparoscopy in healthy patients?
This study aimed to assess the oxygen flow necessary to maintain satisfactory oxygen saturation when administered via a nasopharyngeal catheter. Oxygen saturation was displayed by a pulse oximeter and/or measured in arterial blood samples. Thirty-six healthy women scheduled for elective diagnostic laparoscopy were anaesthetized using thiopentone, fentanyl and O2/N2O. Atracurium was used as relaxant which was reversed with atropine and neostigmine. Arterial samples were obtained prior to anaesthesia, on arrival in the postoperative ward and 1 h postoperatively. Oxygen saturation was monitored postoperatively using a pulse oximeter. The patients were randomly divided into three groups which received either no oxygen, 2 l O2/min or 4 l O2/min. On arrival in the postoperative ward 15% of the patients were below the normal limit of O2 saturation (94%). In patients receiving 2 l or 4 l O2, oxygen saturation was well above normal values. In patients receiving no oxygen, two had low oxygen saturation (92% and 93%). Comparing saturation values obtained in arterial samples with values measured with pulse oximetry gave r = 0.79. It is concluded that all patients should be given oxygen in the immediate postoperative period. Increasing oxygen flow from 2 to 4 l/min had no major effect on oxygen saturation. These results were obtained in healthy patients following minor abdominal surgery.
Adult↗
Experience with vecuronium during long-lasting surgery.
Our knowledge of the possible cumulative properties of vecuronium is limited. Previous studies have shown a tendency towards an increased duration of effect, a slightly prolonged recovery time, as well as an increased variation in duration of effect. We have studied 15 patients scheduled for middle-ear surgery. During i.v. N2O-O2 anaesthesia the twitch response of the adductor pollicis muscle was recorded after supramaximal stimulation of the ulnar nerve at the wrist. Prior to tracheal intubation a bolus dose of vecuronium was given (0.08 mg/kg body weight). During surgery supplementary doses of 0.02 mg/kg body weight were given at a train-of-four (TOF) ratio of 0.25. The duration of effect (DUR-IT-25) and recovery time from a TOF ratio of 0.10 to 0.25 (Recovery-IT-10-25) were recorded. When comparing 10 iteration doses, the mean DUR-IT-25 in the 15 patients studied showed only minor variations (n.s.). Each patient had a near constant interval between the iteration doses; however, a noteworthy variation between individuals was found. Recovery-IT-10-25 was 250 +/- 80 (mean +/- s.d.) 240 +/- 80 and 260 +/- 80 s comparing the second, sixth and tenth iteration doses, respectively. In conclusion, the duration of effect varied considerably between patients. Each patient showed, however, a near constant iteration interval and a recovery time with only small variations. This indicates that cumulation is unlikely to exist following repetitive administration of vecuronium of 0.02 mg/kg body weight.
Adolescent↗
Striated muscle tissue oxygenation and lactate levels during normo-, hyper- and hypocapnia. A study in the rabbit.
The relationship between striated muscle tissue oxygenation during hyper- and hypocapnia, and lactate levels and venous pO2 (pvO2) was studied in a rabbit model. Seven rabbits were ventilated with constant volume during ether anesthesia, and arterial pCO2 (paCO2) was varied by addition of CO2. Muscle tissue oxygenation was measured with a multichannel electrode on the striated muscle surface, the results presented as oxygen pressure distributions (OPD:s). The principal result during hypercapnia (paCO2 9.9 kPa) was a tendency toward increased mean oxygen pressure (ptxO2) of the OPD; OPD shape was normal in 5/7 runs. Arterial lactates (aLa) decreased. During duplicate hypocapnia to paCO2 2.9 and 2.8 kPa ptxO2 decreased, but only in 4/14 runs were tissue oxygen pressures (ptO2) below 0.6 kPa found. OPD shape was scattered in 6/14 runs indicating disturbance in regulation of tissue oxygenation (but without signs of hypoxia). An increase in aLa was found, as well as a decrease in arterio-venous lactate difference (avDLa). Lacking direct blood flow measurements, these two results could not be interpreted as increased lactate efflux per se. Muscle lactates (mLa) were high but, on average, not higher than a control group. A decrease in pvO2 was seen during hypocapnia. Subgrouping OPD:s according to shape and presence of low ptO2 values did, however, suggest that lactate was released in cases with low ptO2 values: a covariation was seen in runs with low oxygen pressures between high arterial and muscle lactates, decreased avDLa and pvO2; runs with scattered OPD:s had only intermediately high lactates and low avDLa and pvO2 when compared to normally shaped OPD:s. In this study, hypercapnia influenced striated muscle tissue oxygenation only to a minor degree while hypocapnia influenced it more but not as much as expected. Only when low oxygen pressures were present in the OPD:s were there indications of peripheral lactate release.
Animals↗
Sympathetic activity and haemodynamic variables during spinal analgesia in man.
At present there is a lack of information concerning haemodynamic changes related to the degree of sympathetic blockade during spinal analgesia. In this investigation, involving 36 patients, changes in haemodynamic parameters were studied in 30 patients receiving spinal analgesia and in six patients having "sham spinal" analgesia. Three local anaesthetic solutions were used: bupivacaine without and with glucose and tetracaine with glucose. Skin conductance responses were used to evaluate changes in provoked sympathetic activity. It was found, as in previous studies, that a complete block of sympathetic activity in the foot was seen in only 60% of patients with an average analgesic level of T4. A partial sympathetic blockade was registered up to and above the level of analgesia. In 25/30 cases only minor alterations in cardiac output, heart rate, stroke volume, mean arterial pressure and systemic vascular resistance were seen in spinal analgesia whose level reached on average T4-5. In five cases in whom analgesia reached T4-3, mean arterial pressure fell greater than or equal to 30% with a well-preserved cardiac output, but with complete sympathetic blockade up to T5 and in two cases also in the hand. Only minor differences were observed between the different anaesthetic solutions.
Analgesia↗
A study of halothane-diethyl ether azeotrope and the Oxford miniature vaporizer.
The performances of an Oxford miniature vaporizer (OMV) and a Fluotec Mark III vaporizer filled with an azeotropic mixture of halothane and diethyl ether were studied. Gas concentrations were estimated using an EMMA gas analyser and a MIRAN spectrophotometer. Calibration tables for both vaporizers were derived. In a small clinical series with air as the carrier gas, to which a small amount of oxygen was added, the azeotrope was found to be a satisfactory anaesthetic agent, giving a short awakening time and an almost pain-free postoperative course.
Anesthesia, Inhalation↗
Skin conductance responses during spinal analgesia.
Skin conductance responses (SCR, "sympatho-galvanic reflex") were measured before and during spinal analgesia in 17 patients scheduled for transurethral surgery. Responses were provoked by standardized electrical stimulation over the clavicle opposite to the recording side; alternatively, a short deep breath, pinching, verbal stimuli or sharp sounds were used. Measuring sites (two electrodes 6 cm apart) were the hand, levels T5, T9, T12-L1 and the foot. Spinal analgesia reached a median cephalad level of T4 (mean T4, range +/- 3 segments) 20-25 min after injection. SCR was markedly depressed in the foot in 15 of 17 patients, at T12-L1 in 12 of 17, at T9 in 10 of 17, at T5 in 9 of 16 and in the hand in 6 of 17. Total abolition of the SCR in the foot was accomplished in only seven cases and sympathetic activity reappeared long before regression of analgesia or motor blockade was observed. In four cases of five with an analgesic level T1-T2, the SCR was preserved in the hand. No consistent correlation between blood pressure change and SCR-change was seen. The conclusion from this study is that preganglionic sympathetic B-fibres are more difficult to block than A-fibres during spinal analgesia. The duration of sympathetic blockade was far shorter than analgesia and motor blockade. Thus, sympathetic blockade during spinal analgesia seems to be far less extensive than that described in the literature.
Aged↗
Partial curarization in the postoperative period.
Forty-eight patients subjected to elective surgery were randomly selected for evaluation of neuromuscular transmission in the postoperative period. All patients were anaesthetized with thiopentone, nitrous oxide, fentanyl and pancuronium. On arrival in the postoperative ward, alertness, ability to sustain head lift and the train-of-four (TOF) ratio were estimated. Twenty-five percent of the patients had a markedly impaired neuromuscular transmission which was not acceptable from a clinical standpoint. The given dose of pancuronium was not excessively high and a fairly long time had elapsed between reversal and TOF-ratio measurement. There was a poor correlation between TOF ratio and ability to sustain head lift. The study indicates that residual curarization is a not uncommon fact which clinically is hard to assess. The only wat to avoid residual curarization seems to be to monitor the neuromuscular transmission during anaesthesia.
Adult↗
Can the "sympatho-galvanic reflex" (skin conductance response) be used to evaluate the extent of sympathetic block in spinal analgesia?
The skin conductance response (SCR) (the "sympatho-galvanic reflex") was studied in volunteers and in a few patients undergoing spinal analgesia. Electrical stimulation over the clavicle, breath-holding during inspiration, a short, deep breath and a sharp sound provoked a marked change in conductance not only in the hand and foot but also in dermatomes T5, T9, T12-L1. Thus, the SC response can be used to study sympathetic activity not only in the hand and foot, but also on the chest and abdomen. Electrical stimulation over the clavicle or a short, deep breath were the best means of provoking SC responses in patients receiving spinal analgesia. This restricted pilot study indicates that skin conductance response is maintained at dermatome levels far below anaesthetised levels during spinal analgesia, and a larger study is now under way to investigate these results further.
Abdomen↗
Lung uptake of lidocaine in man as influenced by anaesthesia, mepivacaine infusion or lung insufficiency.
Pulmonary uptake of lidocaine was investigated in patients before surgery, and aimed at elucidating the influence of general anaesthesia, the presence of another local anaesthetic agent in the blood, or the possible impact of lung insufficiency. When the lung uptake of lidocaine, injected as a bolus together with indocyanine green dye, was calculated as uptake at 95% pass of the dye, there were no statistically significant differences between the four groups. When the extraction in each of the arterial blood samples was calculated on the basis of the relation between relative concentrations, there were statistically significant differences, with a general tendency towards higher extraction of lidocaine in the awake, healthy volunteers, not given mepivacaine, compared to the other groups. In the group in whom mepivacaine was infused, the arterial concentration of mepivacaine increased transiently after the injection of lidocaine. This probably reflects a displacement of mepivacaine from binding sites for both agents. From this study, it is postulated that the ability of the pulmonary circulation to clear the blood of lidocaine is high, and that it is not affected markedly by those situations studied in the present investigation.
Adult↗
Portable emergency ventilators. A lung model study.
The ventilatory performance of four portable emergency ventilators (Logic 07, Motivus, Oxylog and Pneupac II) was tested on a lung model. The model consisted of one common (tracheal) tube, two separate (bronchial) tubes in which different obstructions could be applied, and two glass jars filled with water to suitable compliances. Dialled volume was compared to measured volume. The gas distribution produced by the different ventilators was also studied. It was found that all four ventilators could distribute gas to the lungs. The ventilators Logic 07 and Oxylog had acceptable relationships between dialled and measured volume/frequency and they also produced a good final distribution.
Airway Obstruction↗