Using the prone position could help to combat the development of fast hypoxia in some patients with COVID-19.

The world is facing an explosive COVID-19 pandemic. Some cases rapidly develop deteriorating lung function, which causes deep hypoxaemia and requires urgent treatment. Many centres have started treating patients in the prone position, and oxygenation has improved considerably in some cases.

Atrial natriuretic peptide attenuation of renal ischemia-reperfusion injury after major surgery.

Background: Ischemia-reperfusion (I/R) injury is one of the most important pathologic processes causing acute kidney injury. Human atrial natriuretic peptide (hANP) has various effects, including renal protection. The purpose of the present work was to study the effects of intrarenal angiotensin II (Ang II) and investigate the potential of hANP to prevent kidney injury.

Postoperative regional distribution of pulmonary ventilation and perfusion in infants with congenital diaphragmatic hernia.

Background/purpose: Advances in management of patients with congenital diaphragmatic hernia (CDH) have improved mortality rates but with a risk of increased pulmonary morbidity. The prognosis for CDH survivors remains difficult to predict owing to the lack of adequate methods. We used single photon emission computed tomography (SPECT) to measure the regional distribution of ventilation and perfusion in CDH infants to quantify the degree of lung function impairment and relate it to neonatal clinical disease severity.

Inhalation anesthesia increases V/Q regional heterogeneity during spontaneous breathing in healthy subjects.

Background: The underlying mechanism for the increased alveolar-arterial oxygen tension difference resulting from almost all forms of general anesthesia is unknown. We hypothesized that inhalation anesthesia influences the intrapulmonary distribution of ventilation (V) and perfusion (Q), leading to less advantageous V/Q matching.

Methods: Ten healthy volunteers were studied in supine position on two separate occasions, once awake and once during mild anesthesia (sevoflurane inhalation) with maintained spontaneous breathing.

Positive end-expiratory pressure redistributes regional blood flow and ventilation differently in supine and prone humans.

Background: Animal studies have demonstrated an interaction between posture and the effect of positive end-expiratory pressure (PEEP) on regional ventilation and lung blood flow. The aim of this study was to explore this interaction in humans.

Methods: Regional lung blood flow and ventilation were compared between mechanical ventilation with and without PEEP in the supine and prone postures.

Lung ventilation and perfusion in prone and supine postures with reference to anesthetized and mechanically ventilated healthy volunteers.

Background: The literature on ventilation (V) and lung perfusion (Q) distributions during general anesthesia and controlled mechanical ventilation in supine and prone position is contradictory. The authors aimed to investigate whether V, Q, and ventilation to perfusion ratio (V/Q ratio) matching in anesthetized and mechanically ventilated volunteers are gravity dependent irrespective of posture.

Methods: Seven healthy volunteers were studied at two different occasions during general anesthesia and controlled mechanical ventilation.

Nasal nitric oxide and regulation of human pulmonary blood flow in the upright position.

There are a number of evidences suggesting that lung perfusion distribution is under active regulation and determined by several factors in addition to gravity. In this work, we hypothesised that autoinhalation of nitric oxide (NO), produced in the human nasal airways, may be one important factor regulating human lung perfusion distribution in the upright position. In 15 healthy volunteers, we used single-photon emission computed tomography technique and two tracers (99mTc and 113mIn) labeled with human macroaggregated albumin to assess pulmonary blood flow distribution.

Regional lung blood flow and ventilation in upright humans studied with quantitative SPECT.

We used quantitative Single Photon Emission Computed Tomography (SPECT) to study the effect of the upright posture on regional lung blood flow and ventilation. Nine (upright) plus seven (prone and supine) healthy volunteers were studied awake, breathing spontaneously. Regional blood flow and ventilation were marked in sitting upright, supine and prone postures using (113m)In-labeled macroaggregates and inhaled Technegas ((99m)Tc); both remain fixed in the lung after administration.

Oxygen and life on earth: an anesthesiologist's views on oxygen evolution, discovery, sensing, and utilization.

The advent of oxygenic photosynthesis and the accumulation of oxygen in our atmosphere opened up new possibilities for the development of life on Earth. The availability of oxygen, the most capable electron acceptor on our planet, allowed the development of highly efficient energy production from oxidative phosphorylation, which shaped the evolutionary development of aerobic life forms from the first multicellular organisms to the vertebrates.

A technique for lung ventilation-perfusion SPECT in neonates and infants.

Background: Single photon emission tomography (SPECT) of the lung is a well-established non-invasive technique for quantitative assessment of regional lung ventilation and perfusion distribution in children and in adults. However, its application in neonates as well as infants has been scarce because of several practical limitations, such as the trade off between image quality and restricted effective radiation doses and the lack of suitable inhalations agents and administration techniques.

Methods: In this paper, a new technique for quantitative regional lung SPECT based on a passive Technegas administration procedure is described and clinically applied.

Pronounced depression by propofol on carotid body response to CO2 and K+-induced carotid body activation.

Propofol is a commonly used anesthetic agent, and it attenuates hypoxic ventilatory response in humans. Propofol reduce in vivo and in vitro carotid body responses to hypoxia as well as to nicotine in experimental animals. In the present study we examined the effects of propofol on carotid body responses to hypercapnia and K(+)-induced carotid body activation and compared these effects with hypoxia in an in vitro rabbit carotid body preparation.

Posture primarily affects lung tissue distribution with minor effect on blood flow and ventilation.

We used quantitative single photon emission computed tomography to estimate the proportion of the observed redistribution of blood flow and ventilation that is due to lung tissue shift with a change in posture. Seven healthy volunteers were studied awake, breathing spontaneously. Regional blood flow and ventilation were marked using radiotracers that remain fixed in the lung after administration.

A novel molecule with peripheral opioid properties: the effects on hypercarbic and hypoxic ventilation at steady-state compared with morphine and placebo.

Frakefamide (FF), is a new peripherally acting mu-opioid receptor agonist. The aim of this double-blind, randomized, double-dummy, four-way, crossover study was to investigate FF effects on hypercarbic and hypoxic ventilation at steady-state after a 6-h infusion. We compared the effect with 2 clinical doses of morphine (M-small and M-large) and placebo in 12 healthy men.

Effects of neuromuscular blocking agents on central respiratory chemosensitivity in newborn rats.

Neuromuscular blocking agents suppress central respiratory activity through their inhibitory effects on preinspiratory neurons and the synaptic drive from preinspiratory neurons to inspiratory neurons. Central CO2-chemosensitive areas, which partly consist of CO2-excited neurons, in the rostral ventrolateral medulla are thought to provide tonic drive to the central respiratory network and involve cholinergic mechanisms, which led us to hypothesize that neuromuscular blocking agents can inhibit CO2-excited neurons and attenuate respiratory CO2 responsiveness. To test this hypothesis, we used isolated brainstem-spinal cord preparations from newborn rats.

Paradoxical redistribution of pulmonary blood flow in prone and supine humans exposed to hypergravity.

We hypothesized that exposure to hypergravity in the supine and prone postures causes a redistribution of pulmonary blood flow to dependent lung regions. Four normal subjects were exposed to hypergravity by use of a human centrifuge. Regional lung perfusion was estimated by single-photon-emission computed tomography (SPECT) after administration of (99m)Tc-labeled albumin macroaggregates during normal and three times normal gravity conditions in the supine and prone postures.

Therapeutic efficacy by recombinant human granulocyte/monocyte-colony stimulating factor on mucositis occurring in patients with oral and oropharynx tumors treated with curative radiotherapy: a multicenter open randomized phase III study.

Background: Previous studies suggested granulocyte-macrophage-colony stimulating factor (GM-CSF) might be beneficial for radiotherapy-induced mucositis. This trial examined the efficacy of GM-CSF in reducing mucositis of the oral cavity and/or oropharynx compared with conventional treatment.

Methods: Mucositis, documented by a five-grade scale, was defined in patients with tumors of the head-neck.

A novel molecule (frakefamide) with peripheral opioid properties: the effects on resting ventilation compared with morphine and placebo.

In animal models frakefamide (FF) is a potent analgesic that acts as a peripheral active mu-selective receptor agonist. In this double-blind, randomized, double dummy four-way crossover study in 12 healthy male subjects, we investigated the effects on resting ventilation of FF and 2 dose levels of morphine compared with placebo. Each drug was infused for 6 h.

Effect of propofol on carotid body chemosensitivity and cholinergic chemotransduction.

Background: Propofol decreases the acute hypoxic ventilatory response in humans and depresses in vivo carotid body chemosensitivity. The mechanisms behind this impaired oxygen sensing and signaling are not understood. Cholinergic transmission is involved in oxygen signaling, and because general anesthetics such as propofol have affinity to neuronal nicotinic acetylcholine receptors, the authors hypothesized that propofol depresses carotid body chemosensitivity and cholinergic signaling.

Neuromuscular blocking agents block carotid body neuronal nicotinic acetylcholine receptors.

Neuromuscular blocking agents predominantly block muscle type nicotinic acetylcholine receptors as opposed to the neuronal type. However, there is growing evidence that neuromuscular blocking agents have affinity to some neuronal nicotinic acetylcholine receptors. The carotid body chemoreceptor as the essential oxygen-sensing cell, relies on cholinergic signalling.

Inhibitory effects of halothane on the thermogenic pathway in brown adipocytes: localization to adenylyl cyclase and mitochondrial fatty acid oxidation.

Volatile anesthetics such as halothane efficiently inhibit nonshivering thermogenesis as well as the cellular manifestation of that phenomenon: norepinephrine-induced respiration in brown adipocytes. To identify the molecular site(s) of action of such anesthetics, we have examined the effect of halothane on the sequential intracellular steps from the interaction of norepinephrine with isolated brown adipocytes to the stimulation of mitochondrial respiration (=thermogenesis). We did not identify an inhibition at the level of the adrenergic receptors, but a first site of inhibition was identified as the generation of cAMP by adenylyl cyclase; this led to inhibition of norepinephrine-induced expression of the uncoupling protein-1 (UCP1) gene and reduced norepinephrine-induced lipolysis as secondary effects.

Regulation of regional lung perfusion by nitric oxide.

Improved oxygenation has previously been shown in patients with acute lung injury when ventilated in prone position. We hypothesized that this was due to higher regional production of nitric oxide in dorsocaudal lung regions. We measured nitric oxide synthase mRNA expression and nitric oxide production by citrulline assay in ventral and dorsal lung tissue from patients.