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PubMed2000

Acid-base equilibrium during capnoretroperitoneoscopic nephrectomy in patients with end-stage renal failure: a preliminary report.

We have studied the acid-base equilibrium in 12 patients with end-stage renal failure (ESRF) during capnoretroperitoneoscopic nephrectomy. Bupivacaine (12 mL, 0.375%) and morphine (2mg) were given in the lumbar epidural space, and fentanyl (0.5 microg kg(-1)) and midazolam (50 microg kg(-1)) were given intravenously. Anaesthesia was induced by thiopental, maintained with halothane carried by oxygen enriched air (inspired oxygen fraction = 0.35), and ventilation was achieved with a tidal volume of 10 mL kg(-1) at a rate of 12 min(-1). This procedure resulted in a mild degree of respiratory acidosis that was cleared within 60 min. We conclude that capnoretroperitoneoscopic nephrectomy can be performed in patients with end-stage renal failure with minimal transient respiratory acidosis that can be avoided by increased ventilation.

Acid-Base Equilibrium↗
PubMed1991

Acid-base status affects gas exchange in canine oleic acid pulmonary edema.

The effects of acidosis and alkalosis on pulmonary gas exchange were studied in 32 pentobarbital sodium-anesthetized intact dogs after induction of oleic acid (0.06 ml/kg) pulmonary edema. Gas exchange was assessed at constant ventilation and constant cardiac output, by venous admixture calculations and by intrapulmonary shunt measurements using the sulfur hexafluoride (SF6) method. Metabolic acidosis (pH 7.20) and alkalosis (pH 7.60) were induced with HCl and Carbicarb (isosmolar Na2CO3 and NaHCO3), respectively. Hypercapnia was induced by adding inspiratory CO2, whereas pH was allowed to change (respiratory acidosis, pH 7.20) or maintained constant (isolated hypercapnia). Mean intrapulmonary shunt and pulmonary arterial minus wedge pressure difference, respectively, changed from 44 to 33% (P less than 0.05) and from 9 to 10 mmHg (P greater than 0.05) in metabolic acidosis, from 44 to 62% (P less than 0.001) and from 12 to 8 mmHg (P less than 0.01) in metabolic alkalosis, from 40 to 42% (P greater than 0.05) and from 13 to 16 mmHg (P less than 0.05) in respiratory acidosis, from 42 to 52% (P less than 0.05) and from 8 to 12 mmHg (P less than 0.01) in isolated hypercapnia. These results indicate that acidosis, alkalosis, and hypercapnia markedly influence pulmonary gas exchange and/or pulmonary hemodynamics in dogs with oleic acid pulmonary edema.

Acidosis↗
PubMed2001

[The effect of nocturnal oxygen therapy in patients with sleep apnea syndrome and chronic airflow limitation].

Oxygen therapy for patients with sleep apnea-hypopnea syndrome (SAHS) usually causes significant side effects. The aim of this study was to assess the effect of short-term nocturnal oxygen therapy in patients with SAHS and chronic obstructive pulmonary disease. Ten patients with diagnoses of SAHS were enrolled. The patients' mean age was 63 (10) years, mean apnea-hypopnea index (AHI) was 58 +/- 17, mean FVC was 59 +/- 8% of reference and mean FEV1 was 40 +/- 14% of reference. Using a random, single blind design, two polysomnographic studies were performed on two consecutive nights. Oxygen was administered on one night at a mean flow rate of 1.3 +/- 04 l/min and on the other night air was administered at the same rate. Arterial blood gases were analyzed at the end of each study. Oxygen administration improved nocturnal hypoxia and reduced the AHI, which was 40 +/- 20 with oxygen and 58 +/- 17 with air (p < 0.005). Improvement was achieved at the expense of a reduction in the number of hypopneic episodes. No significant differences were observed in apneic episodes and only a slight increase in the duration of hypopneic episodes was observed (21 +/- 7 s with air and 27 +/- 8 s with oxygen [p < 0.01]). Neither quality of sleep nor heart rate changed. Slight respiratory acidosis was observed in 50% of the patients. In conclusion, nocturnal oxygen administration in patients with SAHS and COPD improved nocturnal hypoxia and reduced the total number of respiratory events. However, in these patients oxygen should be administered with care, even when the rate of flow is low, given the tendency for pCO2 and respiratory acidosis to increase.

Humans↗
PubMed2005

Effect of hypercapnia on changes in blood pH, plasma lactate and ammonia due to exercise.

The present study examined the effects of hypercapnia on changes in blood pH, plasma lactate and ammonia due to exhaustive exercise. Six male subjects underwent exercise of increasing intensity until exhaustion: (1) breathing air = MAX (maximal exercise), or (2) under hypercapnia (HC: 21% O(2), 6% CO(2)) that had been maintained from 60 min before to 30 min after exercise = HC; and (3) exercise of the same intensity as HC in air = SUB (submaximal exercise). Arterialized blood was drawn from a superficial vein. Blood pH in HC was significantly lower than in MAX or SUB at rest, at the end of exercise and throughout recovery (P<0.05). Plasma lactate and ammonia concentration in HC was significantly lower than in MAX (P<0.05), and similar to that in SUB at the end of exercise and throughout recovery. Respiratory acidosis resulting from hypercapnia shifted the linear lactate to blood pH relationship during exhaustive exercise below that at normocapnia (P<0.001). The reduced slope of linear blood pH to ammonia relationship under hypercapnia (P<0.001) is attributed to lactic acidosis that is less, due to the lesser work intensity at the end of exhaustion, than that of normocapnia. From these results we conclude that (1) hypercapnia-induced respiratory acidosis promoted the decrease in blood pH due to lactate production throughout recovery; (2) plasma lactate concentration at maximal exercise was lowered under hypercapnia; (3) plasma ammonia concentration at maximal exercise was reduced, probably due to a less intense lactic acidosis.

Acid-Base Equilibrium↗
PubMed1992

Resuscitation from severe acute hypercapnia. Determinants of tolerance and survival.

A 46-year-old man underwent cosmetic facial surgery under general anesthesia. He was ventilated by mask with an oxygen-enriched gas mixture for 4 to 6 h and monitored by pulse oximetry. Despite adequate arterial saturation (SaO2 > 90 percent) throughout the procedure, he remained in a deep coma after termination of anesthesia. Initial arterial blood gas analysis revealed a pH of 6.60 and a PaCO2 of 375 mm Hg. The patient was intubated and placed on mechanical ventilation. As his respiratory acidosis resolved, he regained consciousness quickly and recovered without any neurologic deficits. This case of record extreme hypercapnia and review of the literature demonstrates that survival is possible in acute severe respiratory acidosis as long as tissue anoxia and ischemia are prevented. We discuss the tissue effects of acute hypercapnia and newer aspects of the nature of intracellular pH regulation in critical tissues that afford considerable tolerance to acidosis. The dependence of these mechanisms upon active ion transport underscores the importance of adequate tissue oxygenation and perfusion.

Acidosis↗
PubMed1982

[Changes in metabolic indicators in cattle by season of the year].

The study was aimed at informing about the results of metabolic trials in large cattle stocks for the period from 1977 to 1980, particularly in view of the dynamics of changes in different metabolic parameters in each year season. The histogram method of statistical evaluation was used. Attention is drawn to the prevailing risk factors in each season and it is possible to investigate the general trend of the rise of new metabolic disorders, or suppression of older ones, in large cattle stocks. The risk metabolic factors of each season can be derived from the results. The summer season is characterized by the tendency to metabolic and respiratory acidosis, by the highest elimination of calcium combined with potassium stress, and by a lack of sodium ions. In the autumn the animals show a more pronounced form of metabolic and respiratory acidosis, not always sufficiently compensated; the liver is overloaded, there is a tendency to hypocalcaemia, and ketosis occurs more frequently, often very pronounced. In winter the acid-base balance of blood improved, acidosis is compensated more intensively by the renal route, calcium is increasingly eliminated in the urine, the overload on liver function is at its maximum, and ketosis occurs most frequently. The spring findings included increased elimination of calcium with the urine, the lowest Ca X P product over the whole year (this is in a high correlation with the higher activities of the ALP enzyme). the highest load of nitrogen compounds and worsened haemogenesis. It can be stated that the mentioned results represent some improvement in the metabolic profile as compared with earlier studies. The situation in enzyme activities can be regarded as a factor of deterioration: high activities of alkaline phosphatase documenting a tension in the metabolism of calcium and phosphorus, and increasing occurrence of chronical overloading of liver function, particularly in winter.

Animals↗
PubMed1993

Effect of CO2/pH on the aldosterone response to hypoxia in bovine adrenal cells in vitro.

Acidosis increases and hypoxia decreases aldosterone production from the adrenal zona glomulerosa in vivo, in situ, and in vitro. These effects appear to be located at different steps in the steroidogenic process. Because respiratory acidosis and hypoxemia are common sequelae of chronic lung disease, the present experiments evaluated the interaction of hypoxia and CO2 (with uncompensated or compensated extracellular pH) on aldosteronogenesis in vitro. Bovine adrenal zona glomerulosa cells were stimulated with angiotensin II (ANG II) or adenosine 3',5'-cyclic monophosphate under room air control (21% O2-0% CO2), CO2 per se (21% O2-10% CO2), hypoxia per se (10% O2-0% CO2), and the combination of CO2 and hypoxia (10% O2-10% CO2). Furthermore, under CO2, pH was either allowed to decrease from 7.2 to 6.8 (uncompensated) or its decrease was minimized (> 7.05) with NaOH (compensated). CO2 without pH compensation led to a significant increase in ANG II-stimulated aldosterone release; when the decrease in pH was minimized, CO2 inhibited ANG II-stimulated aldosterone release. Hypoxia inhibited aldosterone release; the inhibitory effect of hypoxia predominated when combined with CO2. In the presence of cyanoketone, pregnenolone production from endogenous precursors (early pathway) was unaffected. However, the conversion of corticosterone to aldosterone (late pathway) was inhibited by low O2 but unaffected by CO2. It is concluded that the inhibitory effect of low O2 on the late pathway predominates over the effects of uncompensated or compensated simulated respiratory acidosis on aldosteronogenesis.

Adrenal Glands↗
PubMed1976

The acute effects of respiratory and metabolic acidosis on renal function in the dog.

1. Effective renal plasma flow, glomerular filtration rate and cardiac output were measured in osmotically loaded dogs before and during comparable acute respiratory and metabolic acidosis. 2. Urine output increased in control dogs and in animals with metabolic acidosis, but declined with respiratory acidosis. Effective renal plasma flow and glomerular filtration rate declined with respiratory and metabolic acidosis. 3. When respiratory acidosis was buffered with sodium bicarbonate, urine volume increased and glomerular filtration rate and effective renal plasma flow were unchanged; with trihydroxymethylaminomethane, urine volume increased but glomerular filtration rate and effective renal plasma flow fell. 4. When metabolic acidosis was buffered with sodium bicarbonate, urine volume increased; with trihydroxymethylaminomethane, urine volume increased but glomerular filtration rate fell. Cardiac output declined only during metabolic acidosis, both buffered and unbuffered. 5. These studies demonstrate that, even with osmotic loading: (1) respiratory acidosis caused a decrease in glomerular filtration rate, effective renal plasma flow and urine volume; (2) metabolic acidosis depresses glomerular filtration rate and effective renal plasma flow but does not change urine volume even though cardiac output falls; (3) sodium bicarbonate is mor effective than trihydroxymethylaminomethane in preserving renal function during respiratory and metabolic acidosis.

Acidosis↗
PubMed2001

Optimal positive end-expiratory pressure (PEEP) settings in differential lung ventilation during simultaneous unilateral pneumothorax and laparoscopy: an experimental study in pigs.

BACKGROUND: A combined thoraco-laparoscopic technique for esophageal resection is technically possible, but it requires special attention to ventilation. The positive insufflation pressure normally used in laparoscopy will, when communication between thorax and abdomen is established, create a pneumothorax. METHODS: We performed an experimental study of differential lung ventilation with different levels of positive end-expiratory pressure (PEEP) settings during thoraco-laparoscopy in anesthetized pigs. RESULTS: Positive pressure insufflation of carbon dioxide (CO2) resulted in elevated pulmonary capillary wedge pressure, hypercarbia, and respiratory acidosis. Hypoxemia, however, developed only at lower settings of PEEP. Heart rate, mean arterial pressure, and cardiac output remained relatively stable. CONCLUSION: Pneumopleuroperitoneum under positive CO2 insufflation pressure had adverse effects on blood gases. Hypercarbia, respiratory acidosis, and hypoxemia were early manifestations that occurred even in the presence of hemodynamic stability. The application of PEEP equal to or above CO2 insufflation pressure improved blood gases; in particular, the hypoxia could be avoided. No beneficial effects of differential lung ventilation were documented.

Animals↗
PubMed1984

Chronic hypercapnia stimulates proximal bicarbonate reabsorption in the rat.

The hyperbicarbonatemia of chronic respiratory acidosis might be maintained by a reduction in filtration rate or an enhancement of tubular bicarbonate reabsorption. To investigate this question, 12 Munich-Wistar rats were exposed to a 10% CO2 atmosphere for 6-8 d. Chronic respiratory acidosis developed, with arterial pH 7.30 +/- 0.01, partial pressure of CO2 (pCO2) 80 +/- 2 mmHg, and total CO2 concentration 45 +/- 1 mM. Single nephron glomerular filtration rate was normal (42 +/- 1 nl/min). Chronic hypercapnia caused absolute proximal reabsorption to be significantly stimulated (1,449 +/- 26 pmol/min) as compared with reabsorption previously observed in normal animals (1,075 +/- 74 pmol/min) or in animals subjected to acute hypercapnia (1,200 +/- 59 pmol/min). This is the first demonstration that proximal bicarbonate reabsorption can be stimulated above normal euvolemic values. When eight animals were subsequently allowed to return toward a normocapnic state (arterial pCO2 46 +/- 1 mmHg) over the course of 1-1.5 h, bicarbonate reabsorption was still significantly higher (1,211 +/- 34 pmol/min) than in similarly alkalotic, normocapnic control groups (994 +/- 45 pmol/min). In conclusion, chronic, but not acute, hypercapnia stimulates absolute proximal bicarbonate reabsorption to exceed the level found in normal euvolemic rats.

Absorption↗
PubMed1990

Intracellular pH during daily torpor in Peromyscus maniculatus.

Intracellular and extracellular acid-base parameters during normothermy and daily torpor were examined in deer mice (Peromyscus maniculatus). [14C]Dimethyloxazolidinedione and [3H]inulin were used to assess intracellular pH in liver, heart, skeletal muscle, and brain. Buffering capacities were determined using tissue homogenates. A significant increase in plasma PCO2 and CCO2 during daily torpor indicates a respiratory acidosis. All tissues experienced a reduction in the calculated dissociation ratio of histidine imidazole groups (alpha imid) during daily torpor (16.5% for brain, approximately 10% for other tissues). Based on comparisons with physicochemical tissue buffering capacities, metabolic compensation of the respiratory acidosis occurred in liver, heart, and plasma, while brain was more acidotic than predicted. The more extensive change in brain alpha imid might influence a regulated decrease in body temperature. Comparison of acid-base parameters during daily torpor and hibernation suggests that the magnitude of acid-base modifications in mammals may be associated with the level of dormancy.

Acid-Base Equilibrium↗
PubMed1998

Respiratory function and extraocular muscle paralysis following administration of pancuronium bromide in dogs.

Pancuronium bromide, a neuromuscular blocking agent, was evaluated in canine cataract surgical patients under general anesthesia to determine its effects on respiratory function and globe position. Two paralytic, anesthetic regimes were studied: one using a standard dosage of 0.066 mg kg-1 pancuronium bromide, given intravenously while providing the patient with ventilatory support, and one using a dosage of 0.022 mg kg-1 in which no ventilatory support was provided. Eye position and anterior vitreal position/displacement were recorded by a surgeon who was blinded as to treatment group. Physiological parameters indicative of respiratory function were monitored. Both dosages of pancuronium produced comparable, neutral globe position within 30 s following administration which lasted for 20-30 min. All patients in the standard dose group experienced uneventful anesthetic episodes with physiological parameters well within the normal ranges. Within 5 min after administration, all patients in the low-dose group developed a pronounced respiratory acidosis (mean arterial pH = 7.07 +/- 0.08; mean PaCO2 = 79.8 +/- 10.7 mmHg), which exceeded a set of predetermined safety limits, and subsequently these dogs received ventilatory support. We conclude that 0.022 mg kg-1 pancuronium rapidly produces an unacceptable level of respiratory acidosis and, as a result, patients receiving neuromuscular blocking agents should routinely receive ventilatory support.

Journal Article↗
PubMed1997

Splanchnic and renal deterioration during and after laparoscopic cholecystectomy: a comparison of the carbon dioxide pneumoperitoneum and the abdominal wall lift method.

UNLABELLED: Carbon dioxide (CO2) pneumoperitoneum together with an increased intraabdominal pressure (IAP) induces a hemodynamic stress response, diminishes urine output, and may compromise splanchnic perfusion. A new retractor method may be less traumatic. Accordingly, 30 ASA physical status I or II patients undergoing laparoscopic cholecystectomy were randomly allocated to a CO2 pneumoperitoneum (IAP 12-13 mm Hg) (control) or to a gasless abdominal wall lift method (retractor) group. Anesthesia and intravascular fluids were standardized. Direct mean arterial pressure (MAP), urine output, urine-N-acetyl-beta-D-glucosaminidase (U-NAG), arterial blood gases, gastric mucosal PCO2, and intramucosal pH (pHi) were measured. Normoventilation was instituted in all patients. MAP increased (P < 0.001) only with CO2 pneumoperitoneum. Minute volume of ventilation had to be increased by 35% with CO2 insufflation. PaCO2 was significantly higher (P < 0.05) for 3 h postoperatively in the control group. Diuresis was less (P < 0.01) and U-NAG levels (P < 0.01) higher in the control group. The pHi decreased after induction of pneumoperitoneum up to three hours postoperatively and remained intact in the retractor group. We conclude that the retractor method for laparoscopic cholecystectomy ensures stable hemodynamics, prevents respiratory acidosis, and provides protection against biochemical effects, which reveal the renal and splanchic ischemia caused by CO2 insufflation. IMPLICATIONS: A mechanical retractor method (gasless) was compared with conventional CO2 pneumoperitoneum for laparoscopic cholestectomy. The gasless method ensured stable hemodynamics, prevented respiratory acidosis, and provided protection against the renal and splanchnic ischemia seen with CO2 pneumoperitoneum.

Adult↗
PubMedDate not supplied

Cellular mechanisms of bone resorption induced by metabolic acidosis.

Metabolic acidosis increases urine calcium excretion without an increase in intestinal calcium absorption, resulting in a net loss of bone mineral. In vitro metabolic acidosis induces bone calcium efflux initially by physicochemical dissolution and subsequently by cell-mediated mechanisms involving inhibition of osteoblasts and stimulation of osteoclasts. In bone, prostaglandins (PGs) are important mediators of bone resorption and we have recently determined that acid-induced bone resorption is mediated by PGs. Utilizing neonatal mouse calvariae in culture, we found that decreasing pH by a reduction in bicarbonate concentration, a model of metabolic acidosis, induced an increase in net calcium efflux and in medium prostaglandin E2 (PGE2) levels, both of which were inhibited in the presence of indomethacin. There was a direct correlation between calcium flux and medium PGE2. If pH is lowered to a comparable degree by an increase in pCO2 to model respiratory acidosis, there was no significant stimulation of net calcium efflux from the calvariae and no stimulation of PGE2 production. We have also shown that metabolic acidosis alters osteoblastic expression of a specific osteoclastogenic factor, RANKL, and this response is also PG dependent. Incubation of calvariae in acid medium stimulated expression of RANKL RNA in parallel with the increased calcium flux. Both responses were inhibited in the presence of indomethacin. Thus metabolic, but not respiratory, acidosis induces production of bone PGE2, which mediates acid-induced bone resorption.

Acidosis↗
PubMed1995

[Controlled hypercapnia: a new strategy in the treatment of severe respiratory insufficiency].

Permissive hypercapnia (PHY) represents an interesting approach in critically ill ventilated patients, because it allows to ensure adequate gas exchange while avoiding the adverse effects related to excessive airway pressures. Its objective is to improve oxygenation while reducing the risk of barotrauma and circulatory impairment. This concept is all the more important when considering that in majority of lung diseases for which MV is applied, lung involvement is highly inhomogeneous, meaning that the functionally normal or near normal areas are the most exposed to the deleterious effects of overdistension. Undesired physiological effects of non massive respiratory acidosis (PaCO2 < or = 80 mmHg, arterial pH > or = 7.15) are reversible and mostly minor. This good tolerance legitimizes two strategies: firstly to accept hypercapnia in conditions such as acute severe asthma for which enforced normalization of PaCO2 would imply potentially lethal complications, and secondly to deliberately induce respiratory acidosis while using very low airway pressures and alveolar ventilation to limit or prevent overdistension lung damage in injured as well as in normal areas. When the cerebral vasodilation induced by CO2 might aggravate a preexisting intracranial disorder, PHY is obviously contraindicated.

Humans↗
PubMed1988

Evaluation of a combination of xylazine, ketamine, and halothane for anesthesia in llamas.

Anesthesia induced by use of a combination of xylazine, ketamine, and halothane, under conditions of spontaneous and mechanically controlled ventilation, was evaluated in 5 llamas positioned in dorsal recumbency. Using chronically implanted catheters, systemic arterial blood pressure, pulmonary arterial pressure, right atrial pressure, heart rate and rhythm, cardiac output, blood pH and gas tensions, body temperature, and respiratory rate were measured before anesthesia induction (baseline), throughout the anesthetic period, and for 1 hour into the recovery period. During anesthesia, llamas undergoing spontaneous ventilation developed hypercapnia and respiratory acidosis. Cardiovascular function was decreased during both types of ventilation. The combination of xylazine, ketamine, and halothane in various doses and 2 ventilation procedures (spontaneous and controlled) provided a reliable method for general anesthesia in llamas, but marked cardiovascular depression developed during anesthesia maintenance with halothane. Spontaneous ventilation resulted in potentially clinically important respiratory acidosis.

Anesthesia, General↗
PubMedDate not supplied

Evolving differences in the presentation of severe asthma requiring intensive care unit admission.

BACKGROUND: The prevalence of asthma in the community has been increasing. Asthma mortality has not followed the same pattern. Patients who present with a severe asthma exacerbation share many characteristics with patients who die from asthma. OBJECTIVE: We examined the differences in the presentation of severe asthma in adults admitted to a medical intensive care unit (MICU) over a 10-year interval. METHODS: We reviewed the records of the MICU at the Columbia Presbyterian Medical Center for all admissions with severe asthma for the period from January 2000 to December 2001. The data collected included the number of admissions per month, baseline characteristics, initial arterial pH and PCO(2), length of ICU stay, and complications. These data were compared with similar data obtained over the period 1990-1991. RESULTS: The number of MICU admissions per month for severe asthma decreased from 3.1 in 1990-1991 to 0.8 in 2000-2001. There was a trend toward a reduction in asthma severity as determined by a decrease in the initial arterial PCO(2) from 80 +/- 27 to 55 +/- 23 mm Hg and an increase in pH from 7.1 +/- 0.14 to 7.23 +/- 0.14 (0.10 > p > 0.05 for both). There was 1 death from severe hypoxemia and respiratory acidosis in the earlier series and no asthma deaths in the later series. CONCLUSION: In our institution, there has been a decline in the number of patients with status asthmaticus requiring ICU admission over the past 10 years and a trend towards less advanced presentations with reduced levels of respiratory acidosis and decreased ICU length of stay. These changes may be related to improved medications, education, or access to care in the community.

Adult↗
PubMed1993

Helium insufflation for laparoscopic operation.

Laparoscopic surgical procedures are becoming simultaneously more commonplace and complex. However, carbon dioxide (CO2) pneumoperitoneum required for these procedures causes a respiratory acidosis. We undertook this study to determine if an alternate insufflating gas, such as helium, prevents this sequelae. Twenty patients undergoing elective laparoscopic cholecystectomy were randomized to receive either CO2 or helium insufflation. Intraoperative parameters, including arterial CO2 (PaCO2), end-tidal CO2, pH, bicarbonate (HCO3-), cardiac output and blood pressure were obtained before, during and at the conclusion of pneumoperitoneum. Effects of the two gases on these variables were compared. The average CO2 rose significantly from 35.7 +/- 1.0 to 50.4 +/- 3.2 (p < 0.0001), while pH decreased from 7.434 +/- 0.014 to 7.286 +/- 0.018 (p < 0.0001) in those who received CO2. No change in PaCO2 was observed in those who received He, although a small decrease in pH from 7.428 +/- 0.011 to 7.392 +/- 0.012 (p < 0.05) was observed. HCO3- decreased slightly in both groups. Increases in blood pressure and pulse rate were independent of the gas received. The cardiac output did not change. Helium insufflation for laparoscopic cholecystectomy does not produce the respiratory acidosis caused by CO2 and, therefore, merits further investigation for use, particularly in patients with underlying respiratory disease.

Adult↗