bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulmonary Complications, Ventilation and Blood Gases after Upper Abdominal Surgery
Authors: Hansen G. , Drabløs P. A. , Steinert R.
Published: January 2009

Forty patients who underwent elective cholecystectomy were examined preoperatively and during the first postoperative week by physical examination, measurement of FVC and FEV1, arterial pH and blood gas analyses, and chest x‐ray. Postoperative pulmonary complications (p.p.c.) were detected in 30 (75%) of the patients. Simple auscultation was the most sensitive tool in discovering p.p.c., but 18 of the 30 patients with complications also had a pathological chest x‐ray.

Obesity, smoking, postoperative naso‐gastric tube and postoperative wound infection were predisposing factors for p.p.c. Six patients with preoperative pulmonary disease all had a progress in their lung pathology. There was no definite relationship of duration of anaesthesia or drainage of the abdominal wound to development of p.p.c.

The patients with p.p.c. showed a deeper and more prolonged fall in Pao2 postoperatively than the normal group. None of the normals showed an arterial Po2 below 70 mmHg in the postoperative course, while 63% of the p.p.c. group did.

FVC and FEV1 showed marked reductions from preoperative values on the first postoperative day, and then gradually increased to near preoperative values after 1 week. Arterial pH and Pco2, showed no definite changes during the postoperative course.
The Need for Fentanyl Supplementation of N2O‐O2Relaxant Anaesthesia in Chronic Alcoholics
Authors: Tammisto Tapani , Tigerstedt Irma
Published: January 2009

In order to find out how the need for analgesic supplementation during N2O‐O2‐relaxant anaesthesia is affected by chronic alcohol consumption, 82 patients with various known alcohol habits were anaesthetized for gastric or biliary surgery. Muscular relaxation was kept constant with the aid of a peripheral neurostimulator, and fentanyl was given in increments of 0.05‐0.1 mg for nociceptive symptoms during the anaesthesia.

For induction, alcoholics (annual consumption above 151 pure alcohol) needed significantly more thiopental/kg body weight than social drinkers (1–151 annually) or non‐alcoholics (< 11 annually), and excitative symptoms were more frequent in alcoholics. A positive correlation was found between fentanyl supplementation and alcohol consumption (r = 0.41), non‐alcoholics requiring on average 3.8 μ/kg/h of fentanyl, as compared with 6.4 μ/kg/h in alcoholics. This correlation was clearer than that found previously under similar conditions by the authors between halothane supplementation and alcohol consumption (r = 0.20). In both studies the correlation was partly due to the higher incidence of gastric surgery among alcoholics, since gastric surgery itself requires more supplementation. An analysis of the different symptoms pointing to the need for fentanyl supplementation revealed that the simultaneous occurrence of several symptoms and the prevalence of motor responses were more common in alcoholics. In one patient halothane had to be used as well. In other patients no special difficulties were observed, and none of the patients reported dreams or recollections. The results suggest that during N2O‐O2‐relaxant anaesthesia the demand for fentanyl supplementation is increased by about 70% in chronic alcoholics with a mean annual consumption of 31 1 pure alcohol.
The Pressure‐Flow Relations of the Canine Brain in Acute Mechanically Induced Arterial Hypertension at Different Levels of Cerebral Blood Flow
Authors: Ekström‐Jodal Barbro , Häggendal Egil , Linder Lars‐Erik , Nilsson Nils Johan
Published: January 2009

Cerebral pressure‐flow relations were studied in anaesthetized dogs during acute arterial hypertension, induced by compression of the thoracic aorta. In one group of animals steady state measurements were made with the radioactive gas elimination method. In another group the immediate changes of blood flow at a blood pressure change, as indicated by variations in the cerebral venous oxygen saturation, were studied with continuous oximetric analyses of the superior sagittal sinus blood. The initial blood flow was varied by variations of the arterial carbon dioxide tension or injections of papaverine. At low or normal blood flows auto‐regulation was efficient up to pressures around 180–200 mmHg, while at higher flows the upper autoregulatory pressure limit was found at lower blood pressures. Above the autoregulatory limit ‐ irrespective of the control flow level ‐ there was a rise in blood flow and a decrease in cerebrovascular resistance.
Arrhythmias During Halothane Anaesthesia II: The Influence of Atropine
Authors: Eikard Bent , Andersen Jens Rikardt
Published: January 2009

The effect of i.v. atropine premedication on cardiac rhythm was studied in healthy adult patients during thiopental‐N2O/O2‐halothane anesthesia without intubation. A higher incidence of arrhythmias was seen in younger patients in close relation to administration of atropine, but the overall incidence during anesthesia was identical in the atropine groups and the control groups. The most common arrhythmias were supraventricular ectopies. None of the ECG irregularities led to serious arrhythmias. No consistent changes in blood pressure were observed as the result of arrhythmias or changes in heart rate.

It is concluded that atropine should be reserved for situations where severe bradycardia and hypotensionoccur, or can be expected to occur, and not given automatically, since cardioacceleration which is inherent in its action may be injurious to patients with limited cardiac reserve.
Studies on Intra‐Pulmonary Gas Distribution in the Extremely Obese Influence of Anaesthesia and Artificial Ventilation with and without Positive End‐Expiratory Pressure
Authors: Hedenstierna Göran , Santesson Joakim
Published: January 2009

Intrapulmonary gas distribution was studied in 10 extremely obese patients: (1) during spontaneous breathing awake; (2) during anaesthesia with controlled ventilation and zero end‐expiratory pressure (ZEEP), and (3) as under (2) but with a positive end‐expiratory pressure of approximately 15 cmH2O (PEEP). Gas distribution was assessed quantitatively by means of a multiple‐breath nitrogen wash‐out technique and subsequent fractional analysis, which permitted the calculation of nitrogen wash‐out delay (NWOD). Gas distribution was also analyzed by means of a single‐breath nitrogen wash‐out in order to determine the slope of the “alveolar plateau.” Gas distribution was within normal limits during spontaneous breathing, judged from multiple‐breath as well as single‐breath wash‐out. With anaesthesia and ZEEP, NWOD was higher, indicating less efficient gas mixing, and the slope of the “alveolar plateau” was twice as steep as during spontaneous breathing. With PEEP, distribution of inspired gas improved (lowered NWOD and flatter slope). Theoretical considerations and clinical experiments led to the conclusion that uneven distribution in the anaesthetized obese is caused both by regional differences in the pulmonary time constants (as in obstructive lung disease) and by airway closure.
Halothane Anaesthesia and Suxamethonium II The Significance of Preoperative Gallamine Administration
Authors: Wisborg K. , Christensen V. , Viby‐Mogensen J.
Published: January 2009

Preoperative administration of gallamine was evaluated during inhalation anaesthesia with nitrous‐oxide and halothane with two administrations of suxamethonium 1 mg/kg body weight, 5 min apart.

Sixty healthy patients were randomly divided into three groups, and pre‐anaesthetic gallamine, 0.3, 0.4 or 0.5 mg/kg body weight, respectively, was administered intravenously 3 min before induction, according to the allocation. Just before induction of anaesthesia the patients were examined for signs and symptoms of partial curarization. After induction of anaesthesia by nitrous‐oxide‐oxygen‐halothane, suxamethonium 1 mg/kg was given intravenously. Exactly 5 min later the same dose was repeated. EGG was monitored continuously and serum potassium, Pao2 and Paco2 were measured at appropriate intervals.

It was found that none of the examined doses of gallamine gave any reliable protection against serious bradyarrhythmias after repeated doses of suxamethonium. Furthermore the higher doses of gallamine caused an unacceptably high frequency of patients with tachycardia and signs and symptoms of partial curarization.
Influence of Intravenously Administered Ephedrine on Splanchnic Haemodynamics and Clearance of Lidocaine
Authors: Wiklund L. , Tucker G. T. , Engberg G.
Published: January 2009

The effects of a 20 mg i.v. bolus of ephedrine sulphate on haemodynamics and plasma lidocaine concentrations were evaluated in eight volunteer subjects receiving a constant i.v. infusion of lidocaine HCI (2 or 4 mg min‐1). Injection of ephedrine caused a significant increase in mean arterial blood pressure, which preceded an elevation of heart rate by about 2 min. Cardiac output and hepatic blood flow, measured at 10 and 20 min after injection, were also increased significantly, while there was a decrease in total peripheral resistance and no change in splanchnic vascular resistance. There were no significant circulatory alterations over the same period in a control group of four subjects on receiving the lidocaine infusion. After ephedrine, the mean splanchnic extraction ratio of lidocaine fell from 0.76 to 0.66 at 10 min, then rose again to 0.71 at 20 min, and these changes were accompanied by a 9% increase in its splanchnic clearance. Extraction and clearance remained unchanged in the control group. The implications of these findings are considered in relation to the use of ephedrine to prevent or treat hypotension after peridural block with local anaesthetic agents.
Diazepam and Flunitrazepam as Induction Agents for Cardiac Surgical Operations
Authors: Clarke R. S. J. , Lyons S. M.
Published: January 2009

Diazepam and flunitrazepam were compared in equipotent doses as induction agents for premedicated patients having cardiac surgery. Both drugs caused a significant fall in arterial blood pressure, a rise in Paco2 and a fall in Pao2. There was no significant difference between the two drugs in onset time of anaesthesia, cardiovascular or respiratory depression, or quality of induction. There was also no significant difference from induction with thiopentone in these respects.

Diazepam, over a 0.2 to 0.6 mg/kg range of doses, showed no difference in toxicity, although induction was clinically smoother with the higher dose.
A Simple Method of Monitoring Carbon Dioxide Output in Anaesthetized Patients
Authors: Christensen K. Nørregaard
Published: January 2009

The mean CO2 output during anaesthesia in paralyzed patients can be monitored by continuous capnographic analysis of the total exhaled gases, the latter being mechanically integrated by pumice canisters. The gas is evacuated from the Hafnia A circuit via an ejector flowmeter. The results are not influenced by the flow rates employed.
Inadvertent Thoracic Duct Catheterization during Transjugular Central Venous Cannulation. A Case Report
Authors: Májek M. , Malatinsky J. , Kadlic T.
Published: January 2009

An aberrant placement of a central venous catheter into the upper part of the thoracic duct with loop formation in the left innominate vein was observed on catheterizing via the left internal jugular vein. The misplacement, which did not have any deleterious effects, was caused by the atypical insertion site of the thoracic duct at the dorsocaudal wall of the left innominate vein and, possibly, by its incompetent closing valve. The stiffness of the nylon catheter used may also have been a contributory factor.

The possible causes of this complication of central venous catheterization are discussed. The preferential use of the right internal jugular vein is stressed.
Evaluation of Impedance Cardiography during Anesthesia in Extremely Obese Patients
Authors: Rasmussen Jens Peter , Eriksen Jørgen , Andersen Jens
Published: January 2009

In three anesthetized markedly obese patients, non‐invasive stroke volumes (the transthoracic electrical impedance method) were compared to simultaneously obtained invasively measured stroke volumes (dye‐dilution method). Close correlations were obtained (r = 0.90‐0.98) between the two methods, although constant lower impedance stroke volumes were found in these patients when the values usually employed for the electrical resistivity of the blood (ζ) were used for calculation of the impedance stroke volume. No statistically significant difference (P> 0.10) between the two methods was found when a ζ of 175 ohm ζ cm was used for the calculations, or when the percentage changes in stroke volumes were analyzed.

The impedance method is safe and reliable; it also permits non‐invasive measurements of stroke volume during anesthesia in markedly obese patients.
Pulmonary Function in Obese Patients Scheduled for Jejuno‐Ileostomy
Authors: Andersen Jens , Rasmussen Jens Peter , Eriksen Jørgen
Published: January 2009

Preoperative pulmonary parameters were evaluated in 37 extremely obese but otherwise healthy patients. They were on average 100.9% overweight. X‐ray of the chest, electrocardiograms, and residual volume, vital capacity, total lung capacity, maximum breathing capacity, forced expired volume in 1 second, and related ratios were all within the normal range. The alveolar‐arterial oxygen gradient and the arterial carbon dioxide tension were also within the normal range. The only abnormal finding was a substantially reduced arterial oxygen tension.

It is suggested that the measurement of functional residual capacity, closing volume, and the slope of the alveolar plateau (phase III in the single breath nitrogen washout technique) might give more valuable information.
Measurement of Rapid Changes in Cardiac Stroke Volume. An Evaluation of the Impedance Cardiography Method
Authors: Secher N. J. , Thomsen A. , Arnsbo P.
Published: January 2009

One hundred and twenty‐nine simultaneous measurements were carried out on seven patients, 67 at rest and 62 during the Valsalva manoeuvre, in order to compare impedance cardiography with the thermodilution method, during rapid changes in cardiac stroke volume and pulmonary blood volume.

A coefficient of correlation of 0.86 was found following linear regression analysis of the whole material. Analysis of the individual patient showed that the mean coefficient of correlation was 0.94 (range 0.91–0.97), and that the slope of the regression lines was 0.41 to 1.82, and further that the mean intercept was 0.2 ml.

It is concluded that impedance cardiography can be employed for measuring the relative intraindividual changes in cardiac stroke volume during the Valsalva manoeuvre, and it is suggested that it may be of use in other situations, such as during haemorrhage or continuous positive pressure ventilation.
Comparison of the Analgesic Effects of Intravenous Nalbuphine and Pentazocine in Patients with Postoperative Pain
Authors: Tammisto T. , Tigerstedt I.
Published: January 2009

One hundred patients, who were in pain during the immediate postoperative period after upper abdominal operations, were included in this double‐blind, between‐patient, two‐dose study. During N2O‐O2‐halothane‐relaxant anaesthesia no analgesics were given. The patients received 0.07 mg/kg or 0.14 mg/kg of nalbuphine or 0.3 mg/kg or 0.6 mg/kg of pentazocine by intravenous injection. Pain and side effects were assessed for 4 h after administration of the test drug, or until the pain returned to the pre‐injection level, when a conventional analgesic was given. The onset of pain relief was similar and the peak effect occurred about half an hour after the injection after both drugs. On a milligram basis, nalbuphine seemed to be about three times as potent as pentazocine. The duration of action seemed to be slightly longer after nalbuphine, but 2 1/2 h after the injection the pain had returned to preinjection level in 2/3 of the patients, even after the higher doses of both drugs. Except for sleepiness, there were few side effects and they were similar after both drugs. No psychotomimetic effects were observed.
Parenteral Use of Diazepam in an Emulsion Formulation. A Clinical Study
Authors: Thorn‐Alquist Anne‐Marie
Published: January 2009

A recently described injection formulation for diazepam, consisting of an oil emulsion where the drug is dissolved in the oil phase, has been found to give a lessened degree of side reactions than commercially available preparations. This emulsion formulation was compared to Valium® inj. as premedication in patients undergoing operation for hernia or varices under epidural anaesthesia.

The effects, measured as the degree of drowsiness according to an arbitrary scale, were found to be equal for the two formulations. Neither was there any difference in blood concentrations in the two application groups, respectively, between the preparations used. The propylene glycol content of Valium inj. is said to cause a delayed release of the drug from the injection site after i.m. application, and this is briefly discussed, as well as the possibility of administering the diazepam emulsion continuously, diluted with Intralipid, without the risk of precipitation.
A Danish Cholinesterase Research Unit
Authors: Viby‐Mogensen J. , Hanel H. K.
Published: January 2009

The organisation and initial experiences of a Danish Cholinesterase Research Unit are presented.

The primary aim of the research unit is to provide a service for determining genotypes and activity of serum cholinesterase (acylcholine‐acyl‐hydrolase E.C. 3.1.1.8.) in patients suspected of having abnormal serum cholinesterase. Centralization of these investigations and use of a standard methodology have permitted the setting up of a central card index of families in Denmark with inherited abnormal serum cholinesterase.

During the first 3 years, a total of 967 individuals have been genotyped. Two hundred patients were referred to the centre following an episode of prolonged apnoea after suxamethonium. In addition, 723 relatives of these 200 patients have been investigated, and 513 warning cards have been issued. Forty‐four individuals were genotyped for reasons not related to prolonged apnoea.

Genetic variations of serum cholinesterase were identified with differential inhibition techniques using dibucaine, sodium fluoride, sodium chloride, succinyldicholine, and urea as inhibitors. It was found that no single inhibitor was able to differentiate between all known genotypes of locus E1. Inhibition of serum cholinesterase by urea, used together with the conventional dibucaine inhibition, gave results which compared favourably with the results obtained with the classical combination of dibucaine and fluoride inhibition. The results indicated that, at least in differentiation of rarer genotypes, urea inhibition may give valuable information not obtainable using fluoride inhibition.

The difficulties in deciding which patients should be issued with warning cards are discussed. It is pointed out that only through close cooperation with the local anaesthetists involved will it be possible to elucidate the connection between the rarer genotypes and suxamethonium sensitivity.
Hydrostatic Pulmonary Edema in the Cat. Effects on Pulmonary Blood and Water Volumes and on Lung Compliance
Authors: Hauge Anton , Bø Gunnar , Aarseth Petter
Published: January 2009

The effect on lung compliance of changes in intra‐ and extravascular volumes has been studied. Such changes were induced by inflation and deflation of a balloon placed in the left atrium in open‐chest cats. Blood constituents were labeled with isotopes, and tissue water content was found from the wet/dry weight ratio. When left atrial pressure (PLA) was elevated to a value not exceeding 32 mmHg (4.256 kPa), there was only a minute increase in tissue water volume, and we observed a reversible reduction in lung compliance related to the rise in lung blood volume. At higher PLA, a rapid rise occurred in extravascular fluid volume, with evidence of alveolar flooding. Earlier experiments have shown that, in isolated perfused lung, a situation of slow, steady increase in interstitial fluid can be created. This does not seem to be the case with lungsin situ:once the lymphatic drainage is unable to cope with transvascular fluid flow, an unstable situation is created. This rapidly leads to alveolar flooding and a fall in compliance in addition to that caused by a rise in blood volume. From our fluid and pressure determinations, we calculated a filtration coefficient (Kf) of 0.45 ml/100 g wet lung × cmH2O × h. This is within the range reported for sheep lungs. Observation of dynamic lung compliance cannot be used for detection of interstitial fluid accumulation. It appears, however, that in contrast to isolated lungs, this phase of edema‐formation rapidly leads to alveolar flooding.
Systemic and Regional Blood Flow During Epidural Anesthesia with Epinephrine in the Rhesus Monkey
Authors: Amory David W. , Sivarajan Murali , Lindbloom Leo E.
Published: January 2009

Hemodynamic and regional blood flow measurements were made in five rhesus monkeys before and 10, 20, 40 and 80 min after induction of high epidural anesthesia (T1) with lidocaine (1%) containing 1:200,000 epinephrine. Following induction of epidural anesthesia with epinephrine, there were significant decreases in heart rate, mean arterial pressure, cardiac output and myocardial and renal blood flow. The percentage of cardiac output received by the brain was significantly increased following epidural anesthesia with epinephrine, thus evidencing autoregulation to maintain cerebral blood flow. Vascular resistance in the lower extremity was significantly decreased during anesthesia, indicating arteriolar dilatation. Also, during anesthesia, the lungs received a significantly increased proportion of the microspheres, suggesting an increased peripheral arteriovenous shunting of microspheres due to the arteriolar dilatation.
The 600 Gram CO2 Absorption Canister: An Experimental Study
Authors: Jørgensen B. , Jørgensen S.
Published: January 2009

Model investigations were performed on a canister containing 600 g of Sodasorb indicator soda lime in a transparent lime compartment used in the Hafnia circle. The CO2 input was 300 ml per min. Carbon dioxide will be efficiently eliminated from the gas mixture conveyed to the patient connection in this system for at least 4 h, irrespective of the rate of fresh gas flow. There was proportionality between the fresh gas inflow and the duration of effective CO2 elimination. The relative efficacy of the CO2 absorption was investigated at different levels in the canister. The temperature in the axis of the lime compartment was 43–52° C, and the temperature of the gas mixture conveyed to the patient attachment 30–35° C.

The colour shift in the lime charge was a reliable indicator of the efficiency of CO2 elimination. The canister should be replaced when the colour shift has progressed to 2/3 of the lime charge.

The canister contains no disposable parts except for the lime charge. All the components of the circle system should be taken apart and cleaned after each anaesthesia.
Spinal Anesthesia with Bupivacaine and Tetracaine in Sheep
Authors: Adams H. Jack , Doherty Dan D.
Published: January 2009

Spinal anesthesia was performed in sheep in order to compare hyperbaric solutions of 0.375 and 0.75% bupivacaine and tetracaine. There was no significant difference between the two compounds in the duration of sensory analgesia in the anal regions nor, at 0.75%, in the time required for complete regression of the block. However, at 0.375% the duration of sensory analgesia and motor block in the hind limbs and the time required for complete regression were shorter with bupivacaine. In addition to exhibiting a higher incidence and a longer duration of motor block in the hind limbs, the sheep that received tetracaine were unable to stand on the hind limbs even after complete regression of block had occurred. Although further studies are required to establish the cause of this phenomenon, we suggest this may reflect a block of proprioceptor fibers.
The Effect on the Splanchnic Blood Flow and Cardiac Output of Various Carbon Dioxide Concentrations during Fluroxene (Fluoromar®) Anaesthesia An Animal Study
Authors: Juhl B. , Einer‐Jensen N.
Published: January 2009

Seven dogs premedicated with pethidine 10 mg/kg body weight, were anaesthetized with mebumal natrium 25 mg/kg body weight i.v. and gallamoni jodidum 80 mg, together with O2‐N2O in a ratio of 1 to 1. Thereafter four dogs were constantly hyperventilated and three constantly hypoventilated under stepwise increasing anaesthesia with fluoromar® (= fluroxene), up to 6% inspiratory concentration. A change was made between the groups at this fluoromar concentration, from hyper‐ to hypoventilation and vice versa, after which the fluoromar concentration was reduced stepwise to 0% inspiratory. During the course of this anaesthesia, the related values for flow, pressure and resistance in the systemic and splanchnic circulations were measured at fluoromar concentrations: 0–1 1/2–3‐6‐6‐3‐1 1/2‐0%.

The relative changes in the systemic circulation during increasing concentrations of fluoromar are independent of hypo‐ or hypercapnia, while the absolute magnitudes of the measured parameters are strongly dependent on the CO2 tensions. The hypercapnic dogs had the highest cardiac output, stroke volume and most rapid pulse, as well as the lowest peripheral resistance. The same group of dogs had the lowest liver blood flow and the greatest splanchnic resistance. The mean pressures in the aorta, right atrium and portal vein were not different between the groups.

A straight line dependence at 6% fluoromar, was demonstrated between cardiac index and Paco2: cardiac index (1‐min‐1‐m‐2) = 1.22 + 0.23 ± Paco2 (kPa), ((cardiac index (1‐min‐1‐m‐2) = 1.22 + 0.03 ± Paco2 (mmHg)), and peripheral resistance and Pao2: peripheral resistance (kPa 1‐1 min) = 12.85—0.5 ± Paco2 (kPa), ((peripheral resistance (dyn‐sec‐cm‐5 ± 10‐3) = 7.72‐0.04 ± Paco2 (mmHg)). The pressure in the portal vein appears to rise and the liver flow to fall with rising carbon dioxide tension, but the relationship is not significant.

In the latter half of the investigation only small changes were demonstrated which could be related to the falling concentration of fluoromar. These were slight rises in the mean pressure of the aorta and cardiac frequency, similar for both groups. In addition, a slight rise in the peripheral resistance and splanchnic resistance were observed in the hypocapnic group. No changes were seen in the cardiac output and liver flow in any of the groups during falling fluoromar concentrations. The absolute magnitude of the measured parameters in relation to the CO2 tension reflects the conditions in the first half of the investigation, but the difference between the groups is less pronounced. This was partly due to the smaller difference in Paco2 between the groups in this part of the investigation and partly due to the time and experimental course.
The Different Responses of the Hepatic Arterial Bed to Hypovolaemia and to Halothane Anaesthesia
Authors: Andreen Magna , Irestedt Lars , Zetterström Bengt
Published: January 2009

Ten dogs were subjected to a period of hypovolaemia (bleeding volume: 2% of body weight) and to a period of halothane anaesthesia (end‐tidal halothane concentration: 1%). Mean arterial blood pressure decreased to 79% of control value during hypovolaemia and to 58% of control value during halothane anaesthesia. Mean total peripheral and preportal vascular resistances increased during hypovolaemia and were unchanged during halothane. Mean hepatic arterial and portal venous blood flows decreased to 82% and 55% of control values, respectively, during hypovolaemia, and to 41% and 56% of control value, respectively, during exposure to halothane. Mean hepatic arterial resistance was unchanged during hypovolaemia, but increased during halothane. Mean hepatic oxygen consumption did not change significantly during hypovolaemia, but decreased during halothane anaesthesia, in spite of an increased extraction of oxygen from both the hepatic arterial and the portal venous blood. Possible mechanisms which may maintain oxygen supply to the liver by increasing the hepatic arterial fraction of total liver blood flow when portal venous blood flow is reduced are discussed. It is concluded that this mechanism is upset or inhibited during halothane anaesthesia.
Antagonism of Fentanyl with Naloxone during N2O+O2+ Halothane Anaesthesia
Authors: Tigerstedt Irma
Published: January 2009

To investigate the antagonistic effect of naloxone on fentanyl‐induced respiratory depression, 55 patients (randomly divided into various study and control groups) were studied during nitrous‐oxide‐oxygen‐halothane anaesthesia. Respiratory depression after 0.1 mg of fentanyl was totally reversed by 10 μg/kg of naloxone, measured as 100% restoration of spontaneous respiration, normal minute volumes and end‐tidal CO2, while 15 μg/kg of naloxone was needed to antagonize 0.2 mg of fentanyl. The respective control groups remained apnoeic. If no fentanyl had previously been administered, there was no difference in the respiratory behaviour of naloxone‐treated and control patients, which indicates that no unspecific analeptic effect of naloxone could be demonstrated. The circulatory changes after fentanyl were nearly reversed by naloxone, as has been found earlier with other narcotics.

Recovery from anaesthesia was scored from 0 to 10 (using a modification of Apgar scores for newborns), and somewhat higher mean scores were obtained with the naloxone‐treated patients than with their controls. However, higher postoperative pain scores were recorded in these patients as well as a higher incidence of nausea and vomiting.

The study demonstrates the dose‐relationships of fentanyl and naloxone for estimation of total antagonism; however, the use of naloxone for partial antagonism at the termination of anaesthesia cannot be based on these findings.
Naloxone as Narcotic Antagonist after Balanced Anaesthesia
Authors: Tigerstedt Irma
Published: January 2009

Different modes of naloxone administration were studied in 100 patients following N2O‐O2‐relaxant anaesthesia, where fentanyl was administered for analgesia according to a standardized dose schedule (mean 4.3 μg/kg/h). After reversal of muscular relaxation, the patients were randomly given naloxone—either 1.0 or 2.5 μg/kg i.v. or 2.5 or 5.0 μg/kg i.m., or none (control). Each group consisted of 20 patients.

Awakening was fastest after 2.5 μg/kg i.v. of naloxone (1.8 ± 0.1 min), the time being significantly shorter (P < 0.025) than in the control group (2.7 ± 0.4 min). After 15 min, the minute volume and frequency of respiration were significantly higher (P < 0.05) in all naloxone groups than in the control group. However, the arterialized venous Pco2 did not show significant differences during the recovery. It is therefore suggested that naloxone reversal may cause an increase in CO2 production. The immediate postoperative pain (score 0–3) was mildest in the control group (1.0 mean) and severest after 2.5 μg/kg i.v. of naloxone (1.8 mean); the difference was statistically significant (P < 0.05). The groups receiving 1.0 μg/kg i.v. and 2.5 μg/kg i.m. did not differ from each other (1.2 mean). Nausea and vomiting were reported more often after 5.0 μg/kg i.m. of naloxone than in the other groups. After moderate doses of fentanyl during balanced anaesthesia, routine use of naloxone does not seem to be necessary, but if rapid recovery is essential, 1.0 μg/kg i.v. or 2.5 μg/kg i.m. of naloxone may be recommended and these doses do not cause a higher incidence of side effects.
Epidural Block in Twin Labour and Delivery
Authors: Gullestad Signe , Sagen Norvald
Published: January 2009

In a clinical study, 28 twin mothers were provided with epidural block during labour and delivery. This group was compared to 24 twin mothers who received conventional analgesics throughout labour. General anaesthesia was administered when operative delivery was indicated in the control group.

In the epidural group, duration of labour was significantly prolonged. A delayed second stage of labour caused an increased number of operative vaginal deliveries.

Intra‐uterine asphyxia was not more frequent in the epidural group. Judged by the Apgar score and the neonatal course, there was no difference between the newborn in the two groups. Neither clinical evaluation, nor acid‐base investigations showed any difference between the condition of Twin I and Twin II in the epidural group.
Intubation of Newborns and Infants: A Solution to the Problem of Water Condensation
Authors: Pedersen Brynjolf
Published: January 2009

Treatment with humidified air in intubated newborns and infants is often complicated by the embarrassing problem of water condensation. This problem is solved by the humidification system described below, in which the tube delivering humidified air is surrounded by an Armaflex® ‐insulated spiral‐wire tube. Through the space between the two tubes, an adjustable air warmer delivers dry air at a temperature and flow rate such that the temperature of the humidified air in the delivery tube is maintained above its dew‐point temperature.
Physiologic Evaluation of the HFPPV Pneumatic Valve Principle and PEEP An Experimental Study
Authors: Borg Ulf , Lyttkens Leif , Nilsson Lars‐Göran , Sjöstrand Ulf
Published: January 2009

In experiments in dogs the ventilatory and circulatory conditions prevailing with the ventilatory pattern in high‐frequency positive‐pressure ventilation (HFPPV) were investigated with use of a pneumatic valve principle and a ventilator system of an “open” character. Keeping the gas input constant the importance of insufflation frequency and insufflation time and the reactions to various levels of positive end‐expiratory pressure (PEEP) were investigated in terms of changes in arterial pH, Pco2and Po2.

With the volumes of delivered gas kept constant, an increasing insufflation frequency from 60 to 100 per min gave a parallel decrease in tidal volume accompanied by lower maximum intratracheal pressures and a significant decrease in alveolar ventilation. Also taking into account the possibilities of inducing a suppression of the spontaneous respiration, higher ventilatory frequencies than 60 per min do not seem to introduce any further advantages.

Including the associated effects on cardiac output and venous admixture, the cardiopulmonary and circulatory parameters studied did not show any substantial changes with PEEP levels below 7.5–10 cm H2O. Thus the level of PEEP, which often is part of the ventilatory pattern in HFPPV, does not seem to have any untoward influence on the circulation (stroke volume, cardiac output, total peripheral vascular resistance) and oxygen transport (arterial oxygen content and oxygen flux) in normovolaemic dogs.
Long‐Term Treatment of Two Patients with Respiratory Insufficiency with IPPV/PEEP and HFPPV/PEEP
Authors: Bjerager Knud , Sjöstrand Ulf , Wattwil Magnus
Published: January 2009

The respiratory centre is a multi‐input system and positive‐pressure ventilation is known to interfere with respiratory control mechanisms. Further, in intermittent positive‐pressure ventilation (IPPV) the ventilatory pattern produced by the ventilator and the lung systems is known to influence pulmonary and cardiovascular functions. High‐frequency positive‐pressure ventilation (HFPPV) has been shown to eliminate respiration‐synchronous variations in blood pressure and blood flow, and at frequencies of 60 per min or more spontaneous breathing ceases almost instantaneously if adequate alveolar ventilation and arterial oxygenation are achieved. However, activation of other inputs to the respiratory centre, e.g. chemo‐receptor inputs, can induce spontaneous respiration during HFPPV. Consequently the balance between excitatory and inhibitory afferents is decisive for the patient's spontaneous respiratory efforts (discoordination) during artificial ventilation.

The balance between excitatory and inhibitory mechanisms during artificial ventilation is illustrated in two patients with pulmonary insufficiency. Both patients exhibited spontaneous respiratory efforts (discoordination) during ventilation with a “conventional” type of respirator (ventilatory frequency 20 per min) despite adequate alveolar ventilation, adequate arterial oxygenation and administration of sedatives and respiratory depressants. During HFPPV, at ventilatory frequencies of 60 per min or more, there was an inhibitory effect on spontaneous respiration, and with adequate alveolar ventilation and adequate arterial oxygenation (obtained at lower inspiratory airway pressures than with a “conventional” type of ventilation) it was possible to discontinue sedatives and respiratory depressants without discoordination occurring between the patient and the ventilator. However, in one of the patients, with decreasing pulmonary compliance and diminishing arterial oxygenation (due to increasing intrapulmonary shunting and cardiac decompensation), spontaneous respiratory efforts were present despite high ventilatory frequencies and administration of sedatives and respiratory depressants.

From experimental investigations reported elsewhere, this study in two patients and similar experience in other patients, it seems that it is easier to adapt a patient to a ventilator which has a negligible compression volume and which is set at a high frequency.
A Clinical Evaluation of High‐Frequency Positive‐Pressure Ventilation (HFPPV) in Laryngoscopy under General Anaesthesia
Authors: Eriksson Ivan , Sjöstrand Ulf
Published: January 2009

A technique for automatic ventilation during laryngoscopy under general anaesthesia was evaluated in a lung model and in 5 patients (3–57 y) submitted for routine laryngoscopy. This technique has been given the name laryngoscopy HFPPV and utilizes an insufflation frequency (f) of 60 per min and a relative insufflation time (t%) of 22%. Ventilation is given via a nasotracheal insufflation catheter.

Laryngoscopy HFPPV permits laryngeal surgery with a virtually unobstructed surgical field under complete muscular relaxation. The alveolar ventilation of the patient may be controlled by adjustment of the pressure of the anaesthetic gas mixture and there is no air entrainment through the larynx during insufflation. This makes possible use of O 2/N 2 O mixtures and the oxygenation of the patient may be controlled by adjustment of the oxygen concentration of the anaesthetic gas mixture. As there is a continuous upward gas flow through the larynx, blood or pieces of loose tissue are not sucked down into the trachea.

A simple ventilation nomogram for clinical use is proposed. Adequately used, this nomogram guarantees safe ventilation during laryngoscopy HFPPV. An FIO2 of 0.3–0.4 gives adequate arterial oxygenation.
High‐Frequency Positive‐Pressure Ventilation (HFPPV) in Neonates and Infants during Neuroleptal Analgesia and Routine Plastic Surgery, and in Postoperative Management
Authors: Heijman Lilian , Nilsson Lars‐Goran , Sjöstrand Ulf
Published: January 2009

The low pulmonary compliance, the high airway resistance and the “rapid” breathing pattern of neonatal and paediatric patients make it necessary to design special ventilators to match the pulmonary physiology of infants.

A ventilator system which also in small children has a negligible compression volume was evaluated in a lung model and during repair of cleft lip and palate in 16 patients under general anaesthesia and in two other infants during other operations. High‐frequency positive‐pressure ventilation (HFPPV) was given with an insufflation frequency (f) of 60 per min and a relative insufflation time (t%) of 32%. In addition, two neonates treated postoperatively with HFPPV are reported.

Despite the “open” character of the ventilator system both intra‐ and postoperative ventilation were uneventful in all patients. The arterial oxygenation was good in all cases, as judged from clinical signs or blood gas analyses. Postoperative ventilation required conventional clinical observation and intermittent analyses of blood.

HFPPV has been shown to depress, or abolish, spontaneous respiration via reflex mechanisms. In all patients in this investigation respiratory movements were absent at normo‐ or slight hyperventilation during HFPPV.
Pneumatic Systems Facilitating Treatment of Respiratory Insufficiency with Alternative Use of IPPV/PEEP, HFPPV/PEEP, CPPB or CPAP
Authors: Sjöstrand Ulf
Published: January 2009

Some respiratory, circulatory and clinical conditions are reviewed in connection with the use of ventilator systems for intermittent positive‐pressure ventilation at a normal frequency (IPPV‐nf). Intermittent positive‐pressure ventilation with considerably higher frequencies (IPPV‐hf) can, with an appropriate pressure and flow pattern (but at the cost of an increased dead space ventilation) provide adequate alveolar ventilation. The type of IPPV‐hf that has been given the name high‐frequency positive‐pressure ventilation (HFPPV) gives a ventilatory pressure/flow pattern that interferes less with circulatory function than IPPV‐nf. Furthermore, the ventilatory pattern of HFPPV has been found to have desirable respiratory and other systemic effects, making this form of artificial ventilation of clinical interest. However, before HFPPV could be considered sufficiently well developed for routine clinical use, further technical refinement and simplification were necessary and the technical, functional and clinical demands on systems for modern respiratory care are therefore discussed.

The ventilatory and circulatory implications of the ventilatory pressure/flow patterns generated in HFPPV have been investigated with previously described ventilator systems for HFPPV, and this has been the subject of separate reports.

Under conditions of high airway resistance and low compliance, volume‐controlled respirator systems are required for efficient artificial ventilation. Satisfactory volume‐controlled ventilation can, however, only be obtained by using systems with a small compressible volume and low internal compliance. Three ventilator systems satisfying these two criteria are described and with these prototype systems for volume‐controlled IPPV the ventilatory pressure/flow pattern of HFPPV may be obtained, i.e. volume‐controlled HFPPV is achieved. Further, these prototype systems are versatile in the respect that they are both able to give (a) volume‐controlled IPPV‐nf or IPPV‐hf (HFPPV), and (b) continuous positive‐pressure breathing in the neonate (CPAP) or in the adult (CPAP or CPPB).

One of the prototype systems has been developed for neonatal intensive care. It has been studied experimentally in a lung model and is used routinely for clinical treatment of neonatal respiratory distress; preliminary clinical reports have been presented previously. The other prototype systems presented have been developed according to the same principles for intensive respiratory care of adults, but they have not yet been used clinically.

The effects of the pressure/flow pattern of the ventilatory systems described in this communication—i.e. pressure/flow‐generated volume‐controlled HFPPV—has been studied in dog experiments and compared with the ventilatory pattern of a conventional respirator system and this will be the subject of subsequent articles.
The Influence of the Ventilatory Pattern on Ventilation, Circulation and Oxygen Transport during Continuous Positive‐Pressure Ventilation An Experimental Study
Authors: Eriksson Ivan , Jonzon Anders , Sedin Gunnar , Sjöstrand Ulf
Published: January 2009

In IPPV, the ventilatory pattern produced by the ventilator and the lung systems is known to influence pulmonary and cardiovascular functions. In this study on dogs the ventilatory pattern of a conventional respirator (Siemens‐Elema Servo Ventilator 900=SV‐900) constituted the norm for comparison with that produced by a system for volume‐controlled HFPPV. The experimental conditions were kept identical (pentobarbital anaesthesia and normoventilation, i.e. arterial PCO2=40 mm Hg, pH=7.4 and constant FIO2 of the inspired air).

At comparable alveolar ventilation the intratracheal peak and mean pressures were always higher during ventilation with SV‐900 than during HFPPV. The calculated alveolar oxygen partial pressure (PAO2) was almost identical with the two systems. The differences in arterial PCO2 and PO2 between SV‐900 and HFPPV were negligible when 30% O2 was used. The total peripheral resistance (TPR) was lower during ventilation with HFPPV, and although the cardiac output (CO) and stroke volume (SV) were greater during HFPPV, calculations of the tension‐time index (TTI) revealed no differences between the two ventilator systems. With 30% O2 the alveolo‐arterial PO2 difference (A‐aDO2) was smaller, the oxygen flux (OF) greater and the venous admixture lower during ventilation with HFPPV.

The lower TPR during ventilation with HFPPV in association with a higher cardiac output and improved tissue perfusion indicates that the ventilatory pattern in volume‐controlled HFPPV interferes less with the cardiovascular functions. Thus, HFPPV appears able to give better myocardial and circulatory efficiency.
Summary of Experimental and Clinical Features of High‐Frequency Positive‐Pressure Ventilation—HFPPV
Authors: Sjöstrand Ulf
Published: January 2009

In order to eliminate the respiration‐synchronous variations in blood pressure and heart rate a new method of artificial positive‐pressure ventilation was developed—high‐frequency positive‐pressure ventilation (HFPPV). Since 1967 this technique has been applied in various forms and under greatly differing technical and physiological conditions.

The ventilatory pattern in intermittent positive‐pressure ventilation (IPPV) is the result of the combined conditions created by the ventilator and the pulmonary systems and an obvious controversy between physics and physiology arises in the designing of ventilators to match the breathing patterns and pulmonary and cardiovascular physiology of patients with seriously impaired vital functions.

A summary is given of the different types of techniques and the physiological parameters, morphology and functions studied in HFPPV. In order to overcome the increased VD/VT ratio and to provide satisfactory alveolar ventilation in HFPPV, certain basic technical and functional characteristics must be inherent in the ventilator system used. For example in the patient circuit of ventilator systems for HFPPV of an “open” character and for volume‐controlled ventilation there is a negligible compression volume. In a ventilator system for volume‐controlled ventilation, which has a negligible compression volume, inspiration has a decelerating character and the roles of volume as a primary parameter and pressure as a secondary parameter should theoretically function in a desired manner.

The major characteristics of the ventilatory pattern of HFPPV are (a) a ventilatory frequency about three times as high as in conventional IPPV, (b) smaller tidal volumes and lower airway pressures than in conventional IPPV, (c) inspiratory flow (usually of a decelerating character) without an end‐inspiratory plateau, (d) positive intratracheal and negative intrapleural pressures throughout the ventilatory cycle (presumably with even and efficient pulmonary gas distribution), (e) less circulatory interference than in conventional IPPV and (f) reflex suppression of spontaneous respiratory rhythmicity at normoventilation. These functional characteristics of artificial ventilation would seem to be of decisive importance for the pulmonary and cardiovascular physiology of patients with seriously impaired vital functions.
Glomerular Filtration Rate during Enflurane Anaesthesia
Authors: Jensen B. H. , Ruhwald H. , Berthelsen P. , Bröchner‐Mortensen J.
Published: January 2009

Pre‐ and peroperative determination of glomerular filtration rate (GFR) was performed in 10 patients operated on during enflurane anaesthesia. The mean GFR decreased significantly by 21%. The decrease in GFR is of the same order of magnitude as that reported for most general anaesthetics.