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PubMed1976

Pneumothorax in the respiratory distress syndrome: incidence and effect on vital signs, blood gases, and pH.

We determined the incidence of pneumothorax in 295 infants (mean birthweight, 1,917 gm) with the respiratory distress syndrome (RDS) treated according to the same protocol. Fifty-five infants (mean birthweight, 1,594 gm) developed pneumothorax (incidence, 19%); incidence varied with severity of RDS and intensity of respiratory assistance. Pneumothorax occurred in 3.5% (2 of 58) of infants who received no assisted ventilation and in 11% (14 of 124) of infants who received continuous positive airway pressure (CPAP) as the only form of assisted ventilation; the difference between these two groups is not significant. Forty-nine infants initially treated with CPAP later required mechanical ventilation with positive end-expiratory pressure (PEEP). Pneumothorax occurred in 12 of the 49 (24%) and in 21 of 64 (33%) of those infants initially treated with PEEP; the incidence of pneumothorax for both these groups was significantly higher than for those treated with no assisted ventilation or CPAP only. To assess the value of frequent measurement of vital signs, blood gas tensions, and pH in the recognition of pneumothorax, we analyzed these variables by the cumulative sum statistical technique. We noted the following significant changes associated with pneumothorax: arterial blood pressure, heart rate, and respiratory rate decreased in 77% of cases; pulse pressure narrowed in 51% of cases; Po2 decreased in 17 of 20 cases in which ventilatory settings were constant for at least three hours prior to pneumothorax. However, pH and Pco2 showed consistent changes. Frequent measurements of vital signs and Po2 aid in the early diagnosis of pneumothorax.

Blood Pressure↗
PubMed1979

New parachute cuff and positive end-expiratory pressure to minimize tracheal injury and prevent aspiration.

A new parachute cuff has been tested in combination with a positive end-expiratory pressure (PEEP) on mongrel dogs. During positive-pressure ventilation the intracuff and intratracheal pressures showed synchronous, identical pressure variations, and therefore theoretically with this type of cuff the pressure against the tracheal wall would be minimal. The cuff provided a seal against gas leakage from the lungs throughout the entire test period, i.e., for up to 7 h. To avoid aspiration of mouth contents during the passive exhalation phase, different amounts of PEEP were tested. A PEEP of 4.0--8.0 cm H2O always produced a seal against a column of fluid in the mouth exerting a hydrostatic pressure of 5.4--8.8 cm H2O against the cuff. This seal was maintained during the whole test period. No difference in sealing capacity was found when the cuff was used with a normal respiratory frequency (20/min) and with high-frequency positive-pressure ventilation (60/min). When the PEEP is eliminated, e.g., when the respirator is disconnected for suction of the endotracheal tube, the sealing effect will be abolished. As the cuff extends up into the larynx there will be no pooling of fluid above the cuff. The risk of aspiration can therefore be diminished by suction of oral cavity before disconnecting the respirator. With the use of the pneumatic valve principle together with high-frequency positive-pressure ventilation, an open respirator system can produce a continuous PEEP, thereby preventing aspiration even during suctioning of the tracheal tube.

Animals↗
PubMed1978

Two early Danish respirators designed for prolonged artificial ventilation.

Two Danish respirators are described. The first one was made by August Krogh in 1931 and was based on the principles of the Drinker tank respirator. The original feature was a motor driven by water from an ordinary water tap. It was never widely used, most likely due to practical problems connected with nursing care, etc. The polio epidemic in Copenhagen in 1952 initiated the era of the IPPV-methods and gave rise to the construction of a great number of new respirators. Among the first of these was the Claus Bang respirator. Although it contained many modern features, it proved technically unreliable and was only used for 3-5 years.

Denmark↗
PubMed1977

Mandatory minute volume. A new concept in weaning from mechanical ventilation.

The new concept of mandatory minute volume (MMV) is described. The system provides a preset minute volume to the patient, who breathes spontaneously from it as much as he is able, the remainder being delivered to him via a ventilator. The necessary apparatus has been constructed and has the additional facility of PEEP and/or CPAP up to a level of 15 cmH2O pressure. With possible exceptions, the apparatus allows simpler and more direct control over the patient's PaCO2 than with the IMV system and it ensures, without adjustment, a constant minute volume of fresh gas breathed by the patient, despite minute-to-minute changes in his ability to breathe. Use of the system in conjunction with two commonly used ventilators is described. It should not be difficult to build the facility for MMV into new versions of artificial ventilators.

Humans↗
PubMed1977

Amyotrophic lateral sclerosis presenting with respiratory failure. Diaphragmatic paralysis and dependence on mechanical ventilation in two patients.

Described are two patients whose initial symptom was acute respiratory failure requiring mechanical ventilation. Initially, the cause of the respiratory failure in each patient was obscure, but diaphragmatic paralysis was subsequently demonstrated fluoroscopically in each case. Further neurologic evaluation then supported the diagnosis of amyotrophic lateral sclerosis. Postmortem examination corroborated this diagnosis.

Aged↗
PubMed1976

Renal function in experimental chronic hydronephrosis. V. Net acid excretion capacity in relation to renal pelvic volume after maximal loading with NH4Cl.

In 12 mongrel dogs intravenous loading with ammonium chloride (4 mmol NH4+/kg body weight) was performed before and 2-9 weeks after unilateral hydronephrosis had been produced by ligation of the ureter over an indwelling catheter. In an attempt to satisfy the demand for adequate, constant, alveolar ventilation a special respirator of the high-frequency positive-pressure ventilation (HFPPV) type was used. The acid-base status of the blood was determined before and after the loading and the acidification capacity of each kidney was assessed by measuring the amount of titratable acid and ammonium ions excreted in the urine. In the hydronephrotic kidney the excretion of both titratable acid and ammonium ions was statistically significantly reduced, both compared with the initial values in session I and compared with the healthy kidney in session II. After additional loading with ammonium chloride in session II, however, both kidneys increased their excretions to approximately similar extents. When the excretion was calculated per ml glomerular filtrate, no statistically significant changes were found between sessions I and II, either for the intact or the hydronephrotic kidney. The renal pelvic volume on the hydronephrotic side was measured and related to the reduction of the capacity of the kidney to excrete titratable acid and ammonium ions. No statistically significant correlation was obtained.

Acid-Base Equilibrium↗
PubMed1977

High-frequency positive-pressure ventilation (HFPPV) in neonates and infants during neuroleptal analgesia and routine plastic surgery, and in postoperative management.

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.

Adult↗
PubMed1978

[Surgical treatment of the flail chest (author's transl)].

Six patients with traumatic flail chest underwent surgical stabilization using a procedure introduced by Brunner, Hoffmeister and Koncz (2). Compared with internal stabilization by intermittend positive pressure respiration (IPPR), there are some advantages: Time of artificial respiration is shortened, early mobilization is possible, nursing is easier. The procedure is simple to do and is indicated in those patients, in whom longterm artificial respiration is not necessary for other reasons.

Adult↗
PubMed1978

Long term prognosis of infants with severe idiopathic respiratory distress syndrome. II. Cardio-pulmonary outcome.

75 out of 77 children surviving IRDS with the aid of intermittent positive pressure ventilation have been followed up by age 2.6-7.6 years together with 68 matched controls. The morbidity of lower respiratory tract illnesses was significantly higher in IRDS survivors than in controls affecting a total of 48%, half whom were admitted to hospital on at least on occasion. Only 3 IRDS survivors had pneumonias beyound their third year, however. One child suffered from a moderate stridor due to a partial laryngeal stenosis and one from some dyspnoea at function caused by broncho-pulmonary dysplasia. Thoracic X-ray changes were found significantly more often and more marked in IRDS survivors but on the whole the changes were discrete. Neither the occurrence of pneumonia nor X-ray changes in the IRDS survivors were statistically relatable to a number of neonatal or therapeutical characteristics. Measurements of heart volume, respiratory frequency, oxygen saturation and acid-base values did not differ between the groups. Ventilated IRDS survivors, even with some degree of radiographic demonstrable residua, thus seem to have a good long-term prognosis with regard to lung function, irrespective of a preliminary high morbidity of lower respiratory tract illnesses.

Acid-Base Equilibrium↗
PubMed1978

Lung tissue guanosine 3',5'-monophosphate: effects of ventilation and anesthesia.

In vivo levels of guanosine 3',5'-cyclic monophosphate (cGMP) in rat lung were measured by radioimmunoassay. The basal levels of this agent were found to change depending on the method of killing or anesthesia used. Lowest values were found after microwave irradiation to the head (10.2 fmol/mg wet wt). Values after pentobarbitol anesthesia, with or without atropine, were significantly higher (19-24 fmol/mg). In animals anesthetized with pentobarbital and ventilated at pressures of 7 cmH2O with no end-expiratory pressure, lung cGMP was 42-49 fmol/mg. Ventilation at higher pressures resulted in much higher levels of cGMP (20 cmH2O, 105 fmol/mg; 30 cmH2O, 233 fmol/mg). The response of cGMP to ventilation was not blocked by pretreatment of the animals with atropine. High-pressure ventilation was without effect on lung adenosine 3',5'-cyclic monophosphate.

Animals↗