Evaluation of the effects of helmet continuous positive airway pressure on laryngeal size in dogs anesthetized with propofol and fentanyl using computed tomography

Effect of continuous positive airway pressure helmet on respiratory function following surgical procedures in brachycephalic dogs: A randomized controlled trial

OBJECTIVE

To evaluate the effect of continuous positive airway pressure (CPAP) on respiratory function in the early postoperative period of brachycephalic dogs.

STUDY DESIGN

Prospective, randomized clinical trial.

ANIMALS

A total of 32 dogs.

METHODS

Dogs were assigned to recover with or without CPAP (control) and assessed at specific time points over 1 h. Treatment was discontinued for dogs with a CPAP tolerance score of 3 or more (from a range of 0-4). The primary outcome was pulse oximetry (SpO2). Secondary outcomes were arterial O2 pressure (PaO2)/FiO2 ratio (PaO2/FiO2), arterial CO2 pressure (PaCO2), and rectal temperature. For dogs that reached a CPAP tolerance score of 3 or more, only the data collected up to the time point before discontinuation were included in the analysis. The treatment effect (β) was analyzed using random effects models and the results were reported with 95% confidence intervals.

RESULTS

Dogs were assigned randomly to each protocol. Baseline characteristics in both groups were comparable. Arterial blood gases were obtained in seven control group dogs and nine CPAP group dogs. Treatment did not affect SpO2 (β = -0.1, -2.1 to 2.0) but affected the PaO2/FiO2 ratio (β = 58.1, 2.6 to 113.6), with no effects on PaCO2 (β = -4.3, -10.5 to 1.9) or temperature (β = 0.4, -0.8 to 1.6).

CONCLUSION

In postoperative brachycephalic dogs, CPAP had no effect on SpO2 but improved the PaO2/FiO2 ratio in brachycephalic dogs postoperatively.

CLINICAL SIGNIFICANCE

Continuous positive airway pressure offers a valuable solution to improve gas exchange efficiency, a prevalent concern in postoperative brachycephalic dogs, with the potential to enhance overall outcomes.

Respiratory Effects of Continuous Positive Airway Pressure Administered during Recovery from General Anesthesia in Brachycephalic Dogs

This study aimed to evaluate the benefits of applying 5 cmH2O of CPAP using a pediatric helmet during the recovery phase from general anesthesia in brachycephalic dogs. Brachycephalic dogs undergoing various surgical procedures were included in this study, and a total of 64 subjects were randomly assigned to receive either standard oxygen supplementation (NO-CPAP group) or oxygen supplementation combined with CPAP (CPAP group). This study evaluated arterial blood pH, blood gas partial pressures of O2 and CO2, arterial blood O2 saturation, and related parameters during recovery. The dogs were monitored, and helmet tolerance was assessed using predefined criteria. Of the initially assessed 69 dogs, 64 were enrolled: 32 in the CPAP group and 32 in the NO-CPAP group. Fifteen dogs in the NO-CPAP group were excluded based on predetermined criteria. The CPAP group showed significant improvements in PaO2, PaO2/FiO2, P(A-a)O2, F-Shunt, and respiratory rate compared with the NO-CPAP group (p < 0.001). The incidence of reintubation and helmet intolerance was higher in the NO-CPAP group (18% and 15.6%, respectively) than in the CPAP group (0%). This study highlights the potential benefits of incorporating CPAP, delivered through a pediatric helmet, in the perioperative management of brachycephalic dogs.

Effects of continuous positive airway pressure administered by a helmet in cats under general anaesthesia

OBJECTIVES

The aim of this study was to evaluate the respiratory effects of non-invasive continuous positive airway pressure (CPAP) administered by a helmet in healthy cats under anaesthesia.

METHODS

Fifteen healthy male cats scheduled for castration were anaesthetised with medetomidine (20 µg/kg), ketamine (10 mg/kg) and buprenorphine (20 µg/kg) intramuscularly. When an adequate level of anaesthesia was achieved, a paediatric helmet was placed on all subjects. The helmet was connected to a Venturi valve supplied with medical air and cats received the following phases of treatments: 0 cmH2O (pre-CPAP), 5 cmH2O (CPAP) and 0 cmH2O (post-CPAP). Each treatment lasted 10 mins. At the end of each phase an arterial blood sample was drawn. The following data were also collected: mean arterial pressure, respiratory rate, heart rate and the anaesthesia level score (0 = awake, 10 = deep anaesthesia). The alveolar to arterial oxygen gradient (P[A-a]O2) and the venous admixture (Fshunt) were also estimated. Data were analysed with two-way ANOVA (P <0.05).

RESULTS

The arterial partial pressure of oxygen was higher (P <0.001) at CPAP (103.2 ± 5.1 mmHg) vs pre-CPAP (77.5 ± 7.4 mmHg) and post-CPAP (84.6 ± 8.1 mmHg). The P(A-a)O2 and the Fshunt were lower (P <0.001) at CPAP (4.4 ± 2.3 mmHg; 7.4 ± 3.1%) vs pre-CPAP (18.9 ± 6.4 mmHg; 22.8 ± 4.6%) and post-CPAP (15.6 ± 7.3 mmHg; 20.9 ± 4.6 %). No other parameters differed between groups.

CONCLUSIONS AND RELEVANCE

Non-invasive CPAP applied by a helmet improves oxygenation in cats under injectable general anaesthesia.

Comparison of CPAP and oxygen therapy for treatment of postoperative hypoxaemia in dogs

OBJECTIVE

To compare 5 cmH₂ O of continuous positive airway pressure with oxygen therapy in dogs recovering from general anaesthesia with low SpO₂ values. continuous positive airway pressure is more effective than oxygen therapy in restoring normoxaemia (SpO₂ ≥95%).

MATERIALS AND METHODS

Prospectively, dogs recovering from anaesthesia, with SpO₂ <95% after extubation (T0), were randomised and treated with continuous positive airway pressure (FiO₂ 0.21) or oxygen (O₂ ; FiO₂ 0.35-0.40) therapy. Dogs were monitored with SpO₂ every 15 minutes for 1 hour (T15, T30, T45, T60). Data from normoxaemic dogs (SpO₂ >95%) were used as control (CTR).

RESULTS

Of the 42 dogs enrolled, 34 completed the study. Eleven dogs were treated with O₂ , 10 with continuous positive airway pressure and 13 were CTR. The SpO₂ values at T0 were similar in the continuous positive airway pressure and O₂ groups and were lower than in the CTR group. At T15, T30, T45 and T60, the SpO₂ values in the continuous positive airway pressure group were higher than at T0; these were similar to those of the CTR group at the same time-points. In the O₂ group, SpO₂ values were significantly higher at T45 and T60 than at T0; 45.5% of dogs became normoxaemic at T45 and the remaining dogs became normoxaemic at T60. The average time to reach normoxaemia in the O₂ group (53.1±7.3 minutes) was longer than in the continuous positive airway pressure group (15.0±0.0 minutes).

CLINICAL SIGNIFICANCE

In dogs recovering from general anaesthesia with pulmonary gas exchange impairment, normoxaemia is restored more effectively and rapidly by using continuous positive airway pressure than by oxygen therapy.