bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
Anaesthesia Induction and Lower Oesophageal Sphincter Pressure
Authors: Laitinen S. , Mokka R. E. M. , Valanne J. V. I. , Larmi T. K. I. 
Published: January 2009

The effects of some drugs generally used in premedication for and induction of anaesthesia on the lower oesophageal sphincter (LOS) pressure were investigated in 30 dogs, using the modern oesophageal manometric technique. In thiopental‐induced anaesthesia, a distinct pressure gradient was noted between the LOS and gastric pressure. Atropine eliminated this pressure gradient almost completely. Metoclopramide increased the LOS pressure significantly, and subsequent atropine administration was unable to bring it down. Metoclopramide administered after atropine was unable to elevate the LOS pressure reduced by atropine. Succinylcholine had no observable lasting effect on the LOS pressure.The present findings seem to indicate that of the drugs generally used in premedication for and induction of anaesthesia, atropine significantly reduces the LOS competence, thereby creating favourable conditions for gastro‐oesophageal reflux (GOR) and consequent postoperative pulmonary complications. Use of metoclopramide in premedication for or induction of anaesthesia to eliminate the depressant effect of atropine on the LOS pressure appears to be indicated.
Comparative Evaluation of Neuro‐Muscular Blockade after Pancuronium Administration in Patients with and without Renal Failure
Authors: Dhollander A. A. , Camu F. , Sanders M. 
Published: January 2009

Objective studies about the duration of action of pancuronium (PCM) in renal failure patients are scarce. This study was undertaken to obtain more complete information on spontaneous reversal from PCM‐induced neuromuscular block by monitoring the twitch height to full recovery in the absence of any potentiating agent. Thumb abduction was monitored by a deplacement transducer in end‐stage renal failure (ESRF) and in control patients without renal failure (RF) during neuroleptanalgesia after 0.04 mg/kg and 0.08 mg/kg PCM administration.In the small dosage series, the prolongation of action in ESRF becomes significant for the 75% recovery level (mean values ± s. e. mean:control: 42±7 min, ESRF: 71±10 min, P≤0.05). In the second series (0.08 mg/kg), the 50% recovery level is already significantly delayed in ESRF patients (control: 91±7 min, ESRF: 163±27 min, P≤0.05). The 100% twitch height recovery is obtained with 0.04 mg/kg PCM within 65 f 7 min for patients without RF and within 103±9 min in ESRF patients (P≤0.01). For the 0.08 mg/kg PCM dose, these figures are, respectively, 139±9 min and 214±20 min (P≤0.01).The prolongation of PCM action in ESRF is in agreement with the pharmacokinetics of the drug. Large dosages of PCM must be avoided in ESRF patients because it delays spontaneous full recovery for too long.
Concentration and Elimination of Anaesthetic Gases in Recovery Rooms
Authors: Berner Ole 
Published: January 2009

The investigation includes the measurement of the N2O‐concentration in the recovery rooms of three hospitals with different room ventilation systems. The amount of ventilation determines the elimination of the gas exhaled by the patients and, therefore, is related to the number of patients in the recovery rooms.The investigation has shown that non‐recirculating room ventilation of 500 m3/ pt./hour in recovery rooms gives personnel the same protection against inhalation of anaesthetic gases as is afforded to personnel in operating theatres with scavenging equipment.
The Effect of Halothane Anesthesia on Heart Function During Normovolemia and Hypovolemia in the Dog
Authors: Ahlgren F. Ingemar H. 
Published: January 2009

The effects of halothane anesthesia on coronary circulation and cardiac work were studied in normovolemic and hypovolemic dogs, with the aid of the radioactive microsphere technique.During normovolemia, halothane depressed the heart rate, cardiac output, arterial mean blood pressure and left ventricular work, with a simultaneous decrease in the coronary blood flow. During moderate hypovolemia, the arterial blood pressure was reduced as well as the coronary blood flow; whereas during hemorrhagic hypotension (severe hypovolemia), the arterial blood pressure was slightly increased and the coronary blood flow was unchanged with a reduced heart rate and increased stroke volume.
Cardiovascular Effects of Local Adrenaline Infiltration During Halothane Anaesthesia and Adrenergic Beta‐Receptor Blockade in Man
Authors: Pöntinen P. J. 
Published: January 2009

Adrenergic beta‐receptor blocking agents, alprenolol, propranolol and practolol were given as a prophylactic measure to patients undergoing middle‐ear microsurgery where adrenaline was deliberately infiltrated during halothane‐N2O/O2anaesthesia.These three beta blockers did not differ in their action on heart rate, arterial blood pressure, right ventricular pressure, CVP or peripheral pulse wave in equipotent doses, which were 0.04 mg/kg for alprenolol and propranolol and 0.4 mg/kg for practolol in this study. Atropine caused a highly significant increase in heart rate in the spontaneously ventilating group and maintained blood pressure at higher levels, although the latter difference was not significant.Alprenolol and propranolol offered partial protection for over 40 min against adrenaline‐induced arrhythmias. Occasionally occurring tachyarrhythmias were easily terminated with a further dose of a beta blocker.The effective half‐life of practolol was less than 15 min and doses up to 0.4 mg/kg were unable to prevent arrhythmias during adrenaline challenge.
Peroperative Haemorrhage and Epidural Anaesthesia in Major Abdominal Surgery A Retrospective Study
Authors: Jensen Mogens , Stokke Dag 
Published: January 2009

The peroperative blood loss during resection of the colon, abdominal‐perineal excision of the rectum and cystectomy, according to the method of Bricker, was studied from anaesthetic reports. The period under study was 18 months.A total of 97 patients were divided into two main groups according to the type of anaesthesia (general anaesthesia and general anaesthesia combined with epidural analgesia), as well as into sub‐groups according to the type of operation.An evaluation was made of the blood loss, peroperative mean arterial blood pressure and the duration of the operation.In contrast to reports published earlier on other types of operation, we have been unable to demonstrate a significant reduction in the blood loss of patients given general anaesthesia plus epidural analgesia, despite a lower mean arterial blood pressure during the operation.We ignored any possible postoperative beneficial effect of epidural anaesthesia.
Acute Effects of Furosemide and Mannitol on Renal Function in the Early Postoperative Period
Authors: Järnberg Per‐Olof , Eklund Jan , Granberg Per‐Ola 
Published: January 2009

The effects of furosemide and mannitol on renal function in the immediate postoperative period were studied in 16 patients, who had undergone upper abdominal surgery under neurolept anaesthesia. Renal function was studied preoperatively and during the first postoperative hour with a standard clearance technique. The patients were then randomly given furosemide, 1 mg/kg b.w., or mannitol, 0.5 g/kg b.w. Renal function was further investigated during the following 6 h in periods of varying duration. The injection of furosemide caused an initial increase of renal plasma flow (RPF), while glomerular filtration rate (GFR) decreased. Striking increases of urine flow, fractional sodium, fractional chloride and fractional osmolal excretion were found. These increases reached maximum levels during the second 20‐min clearance period after the injection. Fractional free water reabsorption decreased and during the first 20‐min clearance period it changed into free water clearance. These changes had reached or nearly reached the preoperative control levels after 6 h.The infusion of mannitol caused an initial rise in RPF, while GFR remained stable. Increases were found in urine flow, fractional sodium, fractional chloride, fractional osmolal excretions and fractional free water reabsorption. The changes reached maximum levels during the first 20‐min control period and then gradually returned to the preoperative control levels.Mannitol did not impair GFR and had a milder effect on renal function than furosemide. The losses of sodium and water were much smaller in the mannitol group than in the furosemide group. It is therefore concluded that mannitol should be used as the diuretic of choice in the treatment of postoperative oliguria in patients without known cardiovascular disease associated with increased preload and/or left ventricular insufficiency.