Biomedical subjects

F Lofaso

Publications and source records attributed to F Lofaso.

At least 91 records · Page 5Linked to original sources

PubMed1995

Expiratory muscle activity increases intrinsic positive end-expiratory pressure independently of dynamic hyperinflation in mechanically ventilated patients.

Intrinsic positive end-expiratory pressure (PEEPi) has usually been interpreted as suggesting dynamic hyperinflation, but expiratory muscle activity may also increase end-expiratory alveolar pressure without any additional increase in end-expiratory lung volume. The aim of this study was to assess the influence of expiratory muscle activity, which increases abdominal pressure during expiration and is followed by a sudden drop at end-expiration, on PEEPi measurement in mechanically ventilated patients. We studied eight tracheally intubated patients breathing in an assisted mode in whom expiratory muscle activity was present. PEEPi was measured from the fluctuations of esophageal pressure (Pes) while continuous recording of gastric pressure (Pga) and of changes in abdominal cross-sectional area assessed expiratory muscle activity. PEEPi was also measured by the airway occlusion method in one patient, and diaphragmatic electromyographic activity was recorded to determine the timing of inspiratory muscle activity in two patients. Varying the level of ventilatory support (pressure support level, peak flow rate, or PEEP level) induced increases in measured PEEPi from 6.7 +/- 3.4 to 13.2 +/- 5.9 cm H2O. Concomitantly, the expiratory rise in Pga increased from 3.1 +/- 2.7 to 8.6 +/- 5.0 cm H2O, and the abrupt decay in Pga observed at the end of expiration increased from 4.2 +/- 3.7 to 10.6 +/- 6.1 cm H2O. The drop in Pga and the drop in Pes at end-expiration were synchronous, and these changes, together with electromyographic measurements, were consistent with a concomitant relaxation of the expiratory muscles and activation of the inspiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Haemodynamics and gas exchange before and after coil embolization of pulmonary arteriovenous malformations.

A complete description of haemodynamics and gas exchange before and after percutaneous coil embolization of multiple pulmonary arteriovenous malformations is reported in a 45 year old woman with hereditary haemorrhagic telangiectasis (HHT). Before treatment, whilst the patient complained of severe dyspnoea during daily activities, an intrapulmonary shunt of 31% was measured (inert gas elimination technique), together with a cardiac output (thermodilution technique) of 12.4 L.min-1, resulting in a resting arterial oxygen tension (PaO2) of 8.53 kPa. Effective occlusion of all visible pulmonary malformations resulted in a rapid and major improvement in exercise tolerance, whilst resting PaO2 remained almost unchanged. A second investigation performed 4 months after treatment revealed a persistent intrapulmonary shunt of 19%, a cardiac output of 7.35 L.min-1, and a resting PaO2 of 10.53 kPa. We conclude that major increases in cardiac output largely contribute to the maintenance of PaO2 in patients with multiple pulmonary arteriovenous malformations and intrapulmonary shunt. The benefit of coil embolization is due both to an improvement in arterial oxygenation and a normalization of cardiac output.

Arteriovenous Malformations↗

PubMed1995

Comparative effects of pressure support ventilation and intermittent positive pressure breathing (IPPB) in non-intubated healthy subjects.

We compared the efficacy of three devices delivering assisted non-invasive ventilation with different working mechanisms, during room air breathing and during CO2-induced hyperventilation. In seven healthy volunteers, breathing pattern, respiratory muscle activity and comfort were assessed: during unassisted spontaneous breathing through a mouth-piece (SB); during assisted breathing with a device delivering inspiratory pressure support (IPS); and with two devices delivering intermittent positive pressure breathing (IPPB), the Monaghan 505 (IPPB1), and the CPU 1 ventilator (IPPB2). All three devices were set at 10 cmH2O of maximal pressure. During room air breathing, the work of breathing expressed as power, was significantly greater with the two IPPB devices than with the two other modes (IPPB1 and IPPB2 7.3 +/- 5.2 and 7.2 +/- 6.2 J.min-1, respectively, versus SB and IPS 2.4 +/- 0.7 and 2.3 +/- 3.3 J.min-1, respectively). The difference did not reach the statistical significance for the pressure-time product (PTP). Discomfort was also greater during the IPPB modes. During CO2-induced hyperventilation, considerable differences in power of breathing were found between the two IPPB devices and the other two modes. The PTP was also much higher with IPPB. Transdiaphragmatic pressure was significantly smaller during IPS than during the three other modes (IPS 18 +/- 2.6 cmH2O versus SB 22 +/- 2.6, IPPB1 32 +/- 5.2, and IPPB2: 28 +/- 5.2). Maximal discomfort was observed during the IPPB modes and was correlated with the magnitude of transdiaphragmatic pressure (r = 0.60). Despite similarities in their operational principles, IPS and IPPB had very different effects on respiratory muscle activity in healthy non-intubated subjects. IPPB machines not only failed to reduce patient's effort but also induced a significant level of extra work by comparison to spontaneous ventilation at ambient pressure. Great caution is, therefore, needed in the use of patient-triggered devices for non-intubated patients with acute respiratory failure.

Adult↗

PubMed1995

Evaluation of carbon dioxide rebreathing during pressure support ventilation with airway management system (BiPAP) devices.

The purpose of this study was to evaluate whether carbon dioxide (CO2) rebreathing occurs in acute respiratory failure patients ventilated using the standard airway management system (BiPAP pressure support ventilator; Respironics; Murrysville, Pa) with positive inspiratory airway pressure and a minimal level of positive end-expiratory pressure (PEEP) and whether any CO2 rebreathing may be efficiently prevented by the addition of a nonrebreathing valve to the BiPAP system circuit. In the first part of the study, the standard device was tested on a lung model with a nonrebreathing valve (BiPAP-NRV) and with the usual Whisper Swivel connector (BiPAP-uc). With the BiPAP-uc device, the resident volume of expired air in the inspiratory circuit at the end of expiration (RVEA) was 55% of the tidal volume (VT) when the inspiratory pressure was 10 cm H2O and the frequency was at 15 cycles per minute. The BiPAP-NRV device efficiently prevented CO2 rebreathing but resulted in a slight decrease in VT, which was due to a significant increase in external PEEP (2.4 vs 1.3 cm H2O) caused by the additional expiratory valve resistance. For similar reasons, both the pressure swing necessary to trigger pressure support and the imposed expiratory work were increased in the lung model when the nonrebreathing valve was used. In the second part of the study, seven patients weaned from mechanical ventilation were investigated using a randomized crossover design to compare three situations: pressure support ventilation with a conventional intensive care ventilator (CIPS), BiPAP system use, and BiPAP-NRV. When we compared the BiPAP system use with the other two systems, we observed no significant effect on blood gases but found significant increases in VT, minute ventilation, and work of breathing. These findings are experimental and are clinical evidence that significant CO2 rebreathing occurs with the standard BiPAP system. This drawback can be overcome by using a non-rebreathing valve, but only at the expense of greater expiratory resistance.

Adult↗

PubMed1994

[Survey of the quality of sleep during the perioperative period. Study of factors predisposing to insomnia].

In order to assess the quality of sleep in surgical patients the amount of self-rated postoperative insomnia and its predisposing factors, we conducted a three-fold questionnaire * survey in 176 consecutive patients undergoing elective orthopaedic, vascular or abdominal surgery. The first questionnaire was completed the day preceding surgery, the second at the day of discharge and the third two weeks later. This survey concerned the patient's general status, his usual sleep profile and factors which could interfere with sleep (hypnotics, pain, environmental factors) throughout the study period. It allowed quantification of these parameters and the assessment of their time-course. Perioperative insomnia appeared to be a long-lasting phenomenon which persisted after discharge. Factor analysis and multiple regression models showed that postoperative, self-rated insomnia was multifactorial and mainly explained by the amount of postoperative pain (p = 0.035).

Adult↗

PubMed1994

Respiratory response to inhaled CO2 during positive inspiratory pressure in humans.

To investigate ventilatory CO2 sensitivity during inspiratory pressure support (IPS), we administered inspiratory CO2 [fractional concn (FICO2) 0.01, 0.03, or 0.05] in eight normal subjects without (CTRL) or with (Pinsp) positive inspiratory airway pressure (5 or 10 cmH2O). At CTRL and low IPS, CO2 inhalation led to a significant increase in tidal volume (VT) with nearly identical slopes in the plot of VT vs. end-tidal PCO2. At the high IPS level, VT at FICO2 of 0 was significantly above the value at lower Pinsp and did not increase with CO2 unless FICO2 was elevated to > 0.03. There was very little effect of either Pinsp or FICO2 on respiratory frequency and respiratory timing. The data suggest that the CO2 sensitivity of ventilation is similar at low levels of IPS as during CTRL. However, at high levels of IPS, VT is determined largely by the passive inflation and, thus, independent of CO2. CO2 has to be elevated to increase the respiratory drive before VT becomes CO2 sensitive.

Administration, Inhalation↗

PubMed1994

Acoustic method to estimate the longitudinal area profile of endotracheal tubes.

A problem in mechanical ventilation is the accumulation of mucus secretions in the endotracheal tube (ETT), which tends to reduce the patent cross-sectional area. Here we characterized the extent and locus of the ETT obstruction using an acoustic reflection method recently modified to be applied at bedside. Experiments were conducted both in vivo in 10 intubated patients and in vitro in ETT with or without known constrictions of 1 to 3 mm over 5 cm, located at various distances from the ETT entry: 5, 10, 15, and 20 cm. Acoustic results were compared with the results obtained by an hydraulic reference method, which was the only method available to measure ETT obstruction in mechanically ventilated patients. In vivo acoustic results showed that area reductions were maximal near the tracheal extremity of the ETT, with a range from 2 to 36% (mean value 13 +/- 10%), when estimated relative to the area measured in an unused ETT of the same inner diameter (7 to 9 mm). Statistical analysis of the differences between acoustic reflection data and hydraulic data showed that the two methods did not differ significantly. In vitro acoustic results obtained in constricted ETT showed a highly significant correlation with the actual area (r = 0.97, p = 0.0001). Thus, reductions in ETT area may be detected, quantified, and located by the present acoustic reflection method, which therefore provides a means to avoid emergency extubation because of ETT obstruction.

Acoustics↗

PubMed1994

Prevalence of sleep-disordered breathing in patients on a heart transplant waiting list.

We investigated the prevalence of sleep-disordered breathing in 20 outpatients on a heart transplant waiting list. All were younger than 60 years and had severe stable cardiac failure with a cardiac index below 2.5 L/min/m2 and a left ventricular ejection fraction below 25%. Nine patients (45%) exhibited ten or more apneas and hypopneas per hour of sleep (apneic group). In all patients but one, apneas and hypopneas were predominantly of the central type and occurred during Cheyne-Stokes respiration. There were no statistically significant differences between the apneic and nonapneic groups of patients in terms of age (51 +/- 5 years vs 49 +/- 11), body mass index (24 +/- 4 kg/m2 vs 22 +/- 3), cardiac index (1.87 +/- 0.35 L/min/m2 vs 1.84 +/- 0.40), isotopic left ventricular ejection fraction (13 +/- 5 vs 12 +/- 3%), arterial blood gas, or pulmonary function tests. Hypnogram characteristics showed poorer sleep quality in the apneic group than in the nonapneic group, with a larger number of arousals; this difference was found both for arousals lasting more than 30 s (8 +/- 5/h vs 4 +/- 2) and for arousals lasting less than 30 s (18 +/- 16/h vs 5 +/- 6) and was associated with increased wakefulness after sleep onset in the apneic group (138 +/- 82 min vs 84 +/- 45). Arousals were strongly associated with hyperpneic phases of Cheyne-Stokes respiration. We conclude that sleep-disordered breathing is common in patients with end-stage heart disease and adversely affects the quality of sleep.

Cheyne-Stokes Respiration↗

PubMed1994

Changes in respiratory resistance to low dose carbachol inhalation and to pneumatic trouser inflation are correlated.

Inflation of the leg compartments of pneumatic trousers increases thoracic blood volume. The resultant response in respiratory impedence was investigated in nine normal volunteers, and compared with the response to increasing doses of inhaled carbachol. Respiratory impedance was measured by the forced oscillation technique (4-32 Hz), and respiratory resistance at zero frequency (R0) was extrapolated from linear regression analysis of resistive impedance versus frequency. The mean increase in R0 was 31% after inhalation of 125 micrograms carbachol, and 21% after inflation of pneumatic trousers. The percentage changes in R0 following pneumatic trouser inflation highly correlated those induced by inhalation of 125 micrograms carbachol (r = 0.98) Our data demonstrate that, even in normal subjects, pneumatic trouser inflation causes an increase in respiratory resistance, which can be predicted by the response to a low dose of carbachol. These results support the assumption that cholinergic agents might not only be bronchoconstrictors but also vasodilators of the bronchial vessels. At a low dose, the vasodilating action of carbachol could be the major factor involved in the respiratory response.

Adult↗

PubMed1994

Do turbines with servo-controlled speed improve continuous positive airway pressure generation?

Nasal continuous positive airway pressure (CPAP) devices with a servo-mechanism to control pressure have recently been developed. We evaluated six such devices and three conventional systems in terms of effectiveness in maintaining constant pressure. Machines were tested with pressure levels of 5, 10 and 15 cmH2O. Dynamic behaviour was evaluated: 1) by calculating the imposed work of breathing during simulated breath generated by a sinusoidal pump; and 2) by following the fall in pressure after a transient flow of 1 l.s-1. Quasi-static behaviour was evaluated by simulating a predetermined air leak. Under dynamic conditions, work of breathing was lowest with one conventional nasal CPAP device and three servo-controlled nasal CPAP devices; whereas, the highest levels of work of breathing were recorded with two servo-controlled nasal CPAP devices. The pressure-time response to a transient flow yielded similar results, with a significant inverse correlation between pressure values observed after 300 ms and imposed work of breathing during simulated breathing (r = -0.91). Under quasi-static conditions, microprocessor servo-controlled devices exhibited the best performance. These results suggest that microprocessor servo-controlled nasal CPAP devices are not always the best systems for maintaining constant airway pressure in dynamic situations. However, they are more effective in ensuring maintenance of the desired pressure in the event of an air leak at the mask.

Equipment Design↗

PubMed1994

Clinically relevant diaphragmatic dysfunction after cardiac operations.

Phrenic nerve injury and diaphragmatic dysfunction can be induced by cardiac operation. The clinical consequences are not well-established. We evaluated 13 consecutive patients over a 2-year period with unexplained and prolonged difficulties in weaning from mechanical ventilation. The mean time of measurement from the operation day was 31 +/- 19 days (range 8 to 78). With the same technique we also evaluated 12 control patients: four patients at day 1 after cardiac operation while they were still intubated; four normally convalescing patients at day 7 or 8 after cardiac operation; and four patients who required prolonged mechanical ventilation because of another identified cause after cardiac operation. Diaphragmatic function was evaluated at the bedside from esophageal and gastric pressure measurements. A low or negative ratio of gastric pressure swing to transdiaphragmatic pressure swing, indicative of diaphragm dysfunction, was found in all 13 patients (mean -0.39 +/- 0.64). The difference between the 13 patients and all control groups was found to be highly significant. Transdiaphragmatic pressure measured during a maximal voluntary inspiratory effort and transdiaphragmatic pressure measured during a short, sharp sniff were markedly diminished (28 +/- 18 cm H2O and 13 +/- 15 cm H2O, respectively) in the 13 patients, significantly different from values in the four control patients studied at day 7 or 8. Transdiaphragmatic pressure measured after magnetic stimulation in four patients was also markedly reduced (7 +/- 5 cm H2O) as compared with normal theoretic values. Aminophylline infusion had no effect on any of these parameters. In one of two patients evaluated a second time, about 5 weeks later, a marked improvement was observed. Estimating the prevalence of clinically relevant diaphragmatic dysfunction, we found it to be 0.5% when no topical cooling was used and 2.1% when iced slush with no insulation pad was added for myocardial protection (p < 0.005). The most striking finding was that the clinical course of the 13 patients was marked by severe intercurrent events, including cardiorespiratory arrest after early tracheal extubation in 5 patients, nosocomial pneumonia in 11, prolonged mechanical ventilation in all (58 +/- 41 days), and a fatal outcome in 3. We conclude that prolonged postoperative diaphragmatic dysfunction may cause severe life-threatening complications after cardiac operation and can be limited to some extent by avoiding the use of iced slush topical cooling of the heart.

Adult↗

PubMed1993

Frequency of mechanical ventilation and respiratory activity after double lung transplantation.

We investigated the contribution of pulmonary afferent nerve fibers to the control of inspiratory activity in awake humans. Eight double lung transplant outpatients and eight normal subjects were hyperventilated with a mechanical ventilator. Respiratory frequency was increased until no respiratory activity was detectable. Then, by either adding CO2 in the inspired gas or decreasing respiratory frequency, end-tidal PCO2 (PETCO2) was increased until inspiratory activity (i.e. change in inspiratory airway pressure peak and/or time profile) was detected. In normal subjects, PETCO2 threshold for inspiratory muscle recruitment was significantly lower when frequency was decreased than when CO2 was added (31.3 +/- 6.8 Torr vs. 38.2 +/- 8.1 Torr respectively, P < 0.005). This was not the case in the double lung transplant group (31.5 +/- 6.5 Torr vs. 32.9 +/- 5.8 Torr). These findings suggest that pulmonary afferent nerves have an inhibitory effect on inspiratory activity in humans.

Adult↗

PubMed1993

Assessment of the respiratory compliance in awake subjects using pressure support.

Pressure support (PS), a new mode of ventilatory assistance, is known to induce respiratory muscle relaxation. It was used to obtain reliable measurements of the compliance of the respiratory system (Crs) in awake subjects. PS was applied, through a mouthpiece, at four successive levels (0, 0.75, 1 and 1.25 kPa) to 30 healthy subjects. At the highest PS level, the subject's relaxation was obtained as assessed by a decrease in the occlusion pressure from 0.10 +/- 0.06 to 0.05 +/- 0.04 kPa, whereas the minute ventilation increased (from 7.5 +/- 1.5 to 13.8 +/- 3.3 l.min-1), and the end-tidal carbon dioxide tension (PCO2) decreased (from 5.0 +/- 0.4 to 3.2 +/- 0.5 kPa) below its apnoea threshold. In three subjects, respiratory muscle relaxation was confirmed by a fall in diaphragmatic electromyographic activity. Crs was calculated as the ratio of the tidal volume to the corresponding end-inspiratory airway pressure (i.e. PS level) since, at end inspiration, a zero-flow period was obtained. Crs was highly correlated (r = 0.77) to the height (Ht) of the subjects: Crs (l.kPa-1) = 3.56 x Ht (m) -4.86 (+/- 0.23), allowing normal values to be determined. In order to evaluate the applicability of the method to patients, Crs was measured in four patients with scoliosis, and was found to range from 45-82% of the predicted values. It is suggested that this simple method of Crs determination may be used to characterize various chest wall or pulmonary diseases.

Adult↗

PubMed1992

Respiratory response to positive and negative inspiratory pressure in humans.

To investigate the effect of positive or negative inspiratory pressure on respiration, eight subjects breathed, either without or with added external dead space (VD, 600 ml), through either added inspiratory laminar flow resistances (RES; peak inspiratory airway pressure, Pinsp, down to -9 cmH2O) or with inspiratory pressure support (IPS; Pinsp up to +10 cmH2O). IPS, triggered by the subject's inspiratory effort, provided positive airway pressure throughout inspiration, but allowed for attainment of the subject's own respiratory pattern. The following main results were obtained with IPS or RES relative to the control (no IPS, no RES): (1) with VD, IPS led to small, but significant, increases in tidal volume (VT), respiratory frequency (fR) and ventilation (VE), with no changes in inspiratory time (TI) or duty cycle (TI/TT). Mean inspiratory flow (VT/TI) increased, and mouth occlusion pressure 0.1 sec after onset of inspiration (P0.1) decreased significantly with IPS. The changes during RES were essentially in the opposite direction; (2) without VD, similar, but smaller effects were observed, and only the changes in VT/TI and P0.1 during IPS were significant; (3) highly significant decreases were observed during IPS in end-tidal PCO2 (PETCO2); on the average from 39.6 to 29.2 Torr without VD, and from 45.7 to 39.3 Torr with VD breathing. A small, but significant decrease in PETCO2 occurred also during RES with VD. We conclude that while resistive loading is nearly completely compensated with but small changes in PETCO2, inspiratory pressure support leads to marked hyperventilation, which is not effectively counteracted by central timing commands.

Adult↗

PubMed1992

Airway anesthesia during positive and negative inspiratory pressure breathing in man.

We have measured the effects of airway anesthesia (aerosolized 5% lidocaine) on the respiratory pattern during positive or negative inspiratory pressure in 8 resting subjects. The subjects breathed through a 600 ml dead space (peak inspiratory airway pressure, Paw = -2 cmH2O) without or with negative (approx. -5 or -10 cmH2O) or positive (approx. +5 or +10 cmH2O) inspiratory pressure, provided by a laminar flow resistance or a positive pressure source, respectively. Control measurements were performed before and after measurements with airway anesthesia. Measurements included tidal volume, respiratory frequency, ventilation, inspiratory and expiratory duration, occlusion pressure (P0.1) and end-tidal PCO2. None of the parameters measured was significantly altered by airway anesthesia, which was effective in suppressing the cough reflex. We conclude that information from lung afferents that are suppressed with the elimination of the cough reflex is not important for the breathing pattern during resting ventilation with elevated tidal volume (dead space load) and with positive or negative inspiratory pressure.

Adult↗

PubMed1992

Use of the Blasius resistance formula to estimate the effective diameter of endotracheal tubes.

To early detect mucus deposition in endotracheal tubes (ETT), we propose using a geometric, flow-independent parameter, i.e., diameter of the ETT, based on a precise knowledge of ETT flow regime, instead of using the classic flow-dependent ETT resistance based on the empirical, nonlinear Rohrer equation. From the estimated slope of -0.24 derived from Moody diagrams characterizing the pressure-flow relationship in ETT of various inner diameters (D), we first assessed that the Blasius resistance formula slope of -0.25 could be applied to adult-size ETT, meaning that flow remains fully developed, turbulent, and hydraulically smooth (0.5 L/s less than or equal to V less than or equal to 1.4 L/s). Insertion into the ETT of a pressure catheter (external diameter: d) to stimulate in vivo measurements did not modify these results, provided the hydraulic diameter, D* = D - d, was substituted for D in the Blasius formula. The Blasius formula was then used to determine, from in vitro pressure and flow measurements in ETT before intubation and in ETT lined with dry mucus secretions, the effective diameter, shown here to be highly correlated to the actual diameter measured by volumetric water displacement. The effective ETT diameter was measured in eight patients at different stages after oral or nasal intubation. Compared with the actual ETT diameter measured before insertion, the effective diameter was slightly reduced (2.6 +/- 2.5%) during the first week of intubation and was strongly reduced (12.2 +/- 2.8%) during the second week.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1990

Failure of the intracaval filter of Günther to prevent recurrence of pulmonary embolism--report of two cases.

Two out of nine patients in which inferior vena cava interruption was performed with a Günther filter developed a recurrent pulmonary embolism. In both cases, the filter had moved down and the anchoring legs had perforated the wall of the vena cava. The source of the pulmonary embolism was a clotted basket filter. Anticoagulation was given for two weeks in one patient and six months in the other after insertion of the filter, but it had been stopped before the thrombotic event leading to the recurrent pulmonary embolism. The formation of the thrombi had probably been caused by the migration of the filter and the subsequent perforation, which may have been facilitated by the cessation of the anticoagulation.

Adult↗

PubMedDate not supplied

[Ventilatory control in lung transplantation].

Heart/lung transplantation offers a unique opportunity for studying the role of pulmonary innervation on control of breathing. In heart/lung transplant patients the pattern of breathing has been found to remain unaffected at rest and when asleep. In contrast, CO2 breathing studies have yield conflicting results. In heart/lung transplant recipients with normal pulmonary function, the hypercapnic ventilatory response was not different from that seen in control subjects, whereas heart/lung transplant recipients with moderate restriction had a profound depression in the ventilatory response to CO2. These results suggested that pulmonary vagal afferent fibers may have a facilitating effect on the hypercapnic ventilatory response in patients with restriction. This result is in opposition with data from airway anesthesia studies. In studies of the effects of exercise in transplant patients, control of breathing was affected in the same way as in normal subjects with anesthetized airways: transplant patients had an appropriate level of ventilation with a disproportionate increase in tidal volume. In normal subjects after suppression of inspiratory activity by mechanical hyperventilation, hypercapnia at which inspiratory activity muscle recruitment appeared was lower when arterial CO2 was raised by decreasing ventilator ventilation rather than by adding CO2 in the inspiratory line. This was not the case in double lung transplant subjects. These findings suggest that pulmonary afferent nerves have an inhibitory effect on inspiratory activity in humans. In conclusion, pulmonary afferent play a negligible role in the control of breathing of human at rest but are important in regulating the pattern of ventilation during stress conditions and large tidal volume conditions.

Carbon Dioxide↗