Managing Hypothermia – The Darvall System

Only the highly efficient Darvall Cozy Warming Range provides environmentally sensitive solutions to peri-anaesthetic hypothermia in all veterinary patients.

Peri-anaesthetic hypothermia (body temperature below 36^oC or 97^oF) occurs in up to 80% of anaesthetised cats and dogs. This can be due to their small body size, altered peripheral perfusion from premedication & anaesthetic drugs, intubation by-passing the nose, inhaling cold gases, and heat loss from skin surface or open body cavities.

A dual approach to hypothermia management through warming blankets and Heated Breathing Circuits has tangible patient and environmental benefits.

Only the Darvall Cozy Warming Range fits all the requirements to address hypothermia through environmentally efficient patient warming. Darvall’s unique range of specialised patient warming products keeps your veterinary patients warmer at every stage from pre-surgery through to post-operative care supporting safety, speeding recovery and improving surgical outcomes. Shorter patient recovery times result in improved efficiency because patients are ready to be discharged sooner. During surgery, Darvall’s heated breathing circuits combine with our unique low flow anaesthesia capability to further reduce the risk of hypothermia.

Cozy Warming delivers 25% more heat to patients that other warming systems. Darvall’s product range integrates perfectly - Cozy Warming and Heated Breathing Circuits work together to protect patients against the risks associated with hypothermia, significantly reducing temperature loss and speeding return to normothermia.

The Darvall range is the most environmentally sensitive veterinary equipment for managing hypothermia. The greatest environmental impact of any warming device comes from the energy consumed. The Darvall Cozy Warm Air Heater and Cozy Blankets are highly efficient, ensuring minimal energy use but delivering maximum patient benefit. The environmental impact of using Cozy blankets dwarfs the costs of manufacture, cleaning and drying of re-usable but highly inefficient cloth blankets.

Addressing hypothermia is best achieved by a dual approach – a combination of warming blankets accompanied by heated breathing circuits has been shown to be almost twice as effective as blankets alone (Bowling 2021).

Hypothermia during anaesthesia

Peri-anaesthetic heat loss is exponential. Premedication causes vasodilation leading to mild hypothermia; dogs and cats typically lose up to 1^oC (2^oF) over 30 to 60 minutes before anaesthesia induction. This initial drop in core body temperature precedes the precipitous, critical heat loss that occurs in the first 15 to 30 minutes following induction, also caused by vasodilation then shunting of blood to the periphery causing up to 4^oC (7^oF) of heat loss during clip & prep time. Once animals are draped for surgery, heat loss slows.

Stages of Development of Hypothermia During Anaesthesia

Physiological Consequences of Hypothermia in Recovery

Small animal patients that experience peri-anaesthetic hypothermia suffer various physiological impairments:

Slow heart rate and respiratory depression.
Slow metabolism of drugs, which lengthens recovery.
Pain at surgical site due to shivering.
Systemic pain – vasoconstriction reduces the distribution of analgesic drugs.
Airway obstruction in semiconscious patients which can lead to mortality.
Risk of burns with many warming devices.
Slower recovery and time to extubation, which occupies valuable time of the veterinary team members with accompanying cost.

The risk of mortality in small animal anaesthesia, up to 1 in 500 animals, is far higher than in human anaesthetic practice with around 50% of deaths occurring during recovery, when many patients are hyperthermic. (Broadbelt 2008).

Management of peri-anaesthetic hypothermia

Various methods have been deployed in veterinary clinics to address this problem.

Warming intravenous fluids has long been used but is generally ineffective. The amount of fluid that can be administered during an anaesthetic and the calories that fluid can carry make this method inefficient.

The potential to burn patients with non-thermostatically controlled methods that have a surprisingly narrow margin of safety can lead to significant and catastrophic thermal injury. Such devices include electrical heating blankets, jugs of warm water or heated wheat bags. These devices are particularly hazardous in anaesthetised animals where patients cannot move away from the heat source.

Patient safety is paramount for Darvall – our equipment has never burned a patient.

Darvall’s Dual Approach Solution – a combination of warming blankets accompanied by heated breathing circuits – has been shown to be almost twice as effective as warming blankets alone (Bowling 2021).

Forced warm air blanket heating systems are used in human and veterinary medicine.

The Darvall Cozy system can be used in the three phases of anaesthesia:

Pre-warming after pre-medication has been administered, whilst the patient is in its kennel.
During induction, preparation and surgery itself.
During anaesthetic recovery.

Heated anaesthesia breathing circuits provide an additional method of warming patients with immediate warming once animals are intubated and can limit heat loss during clip and prep, prior to draping and the commencement of surgery. A recent study in 7 kg Rhesus macaques demonstrated that using heated breathing circuits alongside warm air blankets significantly enhanced recovery from hypothermia compared with heated blankets alone (Bowling 2021). Clinical experience in veterinary patients reflects this finding and is a valuable addition to any inhalation anaesthetic protocol.

Pre-warming small animals is highly beneficial and can easily be achieved by placing the pre-medicated patient in a warmed kennel. Darvall’s forced warm air blanket system is ideal for use in pre-warming because the Cozy heater delivers a large flow of warm air at constant, thermostatically controlled temperatures via the Cozy Cwik kennel door adapter. The Cozy blanket range designed to fit the entire kennel. Effective pre-warming can prevent the significant and rapid heat loss caused by vasodilation and shunting post-induction.

During induction, clip and prep there can be significant heat loss in part due to the vasodilation of the patient following pre-medication. Use of a warming blanket along with Darvall Heated Breathing Circuits as soon as the patient is intubated can limit heat loss prior to the commencement of surgery. Leaving the animal on a warming blanket once it is fully draped should ensure that further heat loss is minimised.

Once the animal is in recovery getting it extubated is a priority. The time to extubation can be extended by hypothermia. This period occupies valuable time of the veterinary team members with the accompanying cost. Making sure that the patient continues to be warmed using a heated over blanket should optimise recovery time.

Darvall Cozy Patient Warming Innovation

“By vets, for vets”

Darvall innovation delivers superior products for improved patient warming, cost-effective operations and optimum energy usage, ensuring the most environmentally efficient system available for veterinary patients.

Darvall has worked continuously to improve the Cozy warming range from its first iteration.

Compact Cozy warm air heater sits raised up on in-built wheels moulded to fit the heater base to reduce fur and dust inflow. The Cozy has a small footprint with no space occupying wheelbase.
Filter is replaceable by the end user – every 6 months or 500 hours use.
Filter and hose are economic to replace.
Cozy blankets deliver 25% more heat than Cocoon blankets.
Anatomical blanket design hugs the patient, allowing conductive as well as convective warming.
Darvall has the ONLY blanket designed for exotics.
Velcro closure for a secure and easy one-handed connection.
Cozy Cwik kennel door adapter provides easy patient access and protects the heater hose.

Darvall Cozy Warm Air Heater

Warms safely in kennels and surgery.

Takes only 40 minutes to pre-warm a patient, half the time of recovery re-warming.
Simple, low-cost routine maintenance.
Heater LCD Display gives warnings and run time for recording & costing.
Compact, quiet and easy to use.

The Cozy Warm Air Heater is compact and quiet with wheels integrated into the chassis. It has a built-in HEPA filter to ensure that the warm air is cleaner than the air in the kennels or operating theatre. The low-cost filter is replaced by the end user (minimum 500 hours or every 6 months) as is the heater hose.

Key Features of the Cozy Warm Air Heater.

Safe hose-end temperature sensor.
Protective hose cover.
Reliable nozzle-to-blanket connection.
Hose clamp secures to surgery table.
Retractable kennel door hangers built-in.
IV Pole clamp rear mounted.
Elevated above floor dust and hair.
Two fan speeds and four temperature options.

Start warming your patients with the Darvall Cozy Warming Starter Kit. Includes Cozy Warm Air Heater, Cozy Cwik Kennel Door Adapter and eight-blanket sample pack. (Part number 9084).

Darvall Cozy Cwik Kennel Door Adapter

Simplify kennel warming with the Cozy Kennel Door Adapter Kit with universal hose adapter, extension hose and 8-Blanket Sample Pack. (Part number 9842).

Darvall Cozy Warm Air Blankets

Darvall’s complete range of blankets warm in half the time so halving energy consumption, engineered for low resistance with laminar air flow with even surface warming to deliver 25% more heat to patients compared to Vet Cocoon blankets. Cozy’s innovative veterinary designs including our Exotics blanket, are sized to “hug” patients to give highly efficient conductive as well as convective warming. Cozy Kennel blankets are sized for single and double kennels with air inlets on the hinge side of kennel doors to permit patient access without “dragging” the blanket off the patient. Cozy’s unique Velcro secure blanket closure enables one-handed hose nozzle attachment and permits blankets to be easily moved from surgery to kennels.

Blanket Choices

Cloth and reusable warm air blankets are available, which must be washed & dried before reuse; this may appear to reduce the cost and environmental impact. These blankets lose most of their effectiveness once they have been washed and dried. Also, the environmental and monetary costs involved in washing these blankets effectively – electricity, hot water, detergent, drying, employee time etc. is significant and far outweighs the environmental impact of Cozy blankets.

Specially engineered blankets such as Darvall’s Cozy Warm Air Blankets are made of porous material on the contact surface providing optimal heat transfer. They can be reused in some circumstances such as anaesthetic pre-warming and recovery if they are unsoiled. A new blanket is recommended for use in the operating theatre.

Key Features of Cozy Warm Air Blankets.

Complete size range for all veterinary patients including exotics.
Blankets for pre-warming, surgery and recovery.
Close contact designs enable efficient conductive warming.
Securely connect to Darvall’s Kennel Door Adapter.
Velcro closure for simple 1-handed nozzle attachment and permits re-use.
Low surface air flow from Cozy’s unique “pin hole” blanket perforations.
Low air flow with antimicrobial-filtered air maintains sterile surgical environment.
Cost effective for client and clinic.
Environmentally efficient warming.

Upgrade your patient warming system with Darvall Cozy Blankets. Try the sample pack (Part 9775).

Part	Code	Application	Patient Size	Blanket Inflated Size
2979	VET UB CSD	Surgery Under Blanket	Cats & Small Dogs	0.9m (36″) L x 0.4m (16″) W Inflation tube 12cm (5″) diam.
2275	VET UB MLD	Surgery Under Blanket	Medium & Large Dogs	1.16m (46″) L x 0.5m (20″) W Inflation tube 14cm (5.5″) diam.
5310	VET OBDB MLD	Surgery Over Blanket Dentistry Under Blanket	Medium & Large Dogs	1.1m (43″) L x 0.65m (26″) W Inflation Tubes 9cm (3.5″) diam.
5360	VET RB CSD	Single Kennel Blanket Dentistry Under Blanket	Cats & Small Dogs	0.6m (24″) L x 0.65m (26″) W Inflation tubes 8cm (3″) diam.
5359	VET RB MLD	Double Kennel Blanket	Medium & Large Dogs	1.0m (39″) L x 0.65m (26″) W Inflation tubes 9cm (3.5″) diam.
2827	VET EB VSA	Surgery or Kennel Blanket	Exotics & Tiny Animals	0.6m (24″) L x 0.33m (13″) W Inflation tubes 8cm (3″) diam.
9775	Sample Pack	8 blankets – all types	All the above	3 x surgery blankets, 4 x kennel blankets, 1 x exotics blanket

Darvall Cozy Heated Breathing Systems

Cozy Heated Anaesthesia Circuits- Reduce Critical Heat Loss with Warm Air Inhalation from the First Breath.

Darvall’s heated breathing circuits are an innovative solution to the critical post-induction heat loss by safely delivering warmed inspired gases to the patient immediately from the first breath after intubation. In addition, re-warming of hypothermic patients is twice as fast by combining heated circuits with forced warm air blankets. All elements combine as an environmentally responsible, reusable warming system.

Cozy Heated Circuits are a valuable addition to any inhalation anaesthetic protocol.

Start warming your patients from the first breath with the Darvall Cozy Heated Anaesthesia Breathing Circuits Starter Kit that fits any anaesthesia circle breathing system (PN 9855).

Start warming Exotics from the first breath with Cozy Exotics Heated Anaesthesia Starter Kit (PN 10236).

Key Features of the Cozy Heated Breathing Circuit Controller

Reusable warming system for environmental efficiency.
Use with Heated Breathing Circuits, Heated Lack or Heated Qube for exotics.
Safe: temperature sensor at heated hose-end or in the Qube block.
Warming inspired gas to to 35-38^oC (95-100^oF) at the tip of the ET tube or Qube mask.
Two sizes of animal oesophageal/rectal temperature probe available – dog/cat or exotics.
Animal and heated circuit/Qube temperature displayed in ^oC or ^o.
Default setting is warming mode from power up.

Monitoring software – Windows based

USB port for Heat Controller communication.
Use to customise Heat Controller parameter high/low default settings.
Enables remote Heat Controller microprocessor upgrades.
Continuous patient data acquisition and display.
Can record animal, anaesthetic, procedure and temperature data.
Continuous temperature monitoring.

Darvall Cozy Heated Smooth Wall Breathing Circuits

Heating element embedded in the smooth-wall tubing ribbing.
Dual sensors in Y-piece and oesophagus monitor temperature to ensure patient safety.
Low resistance, low volume smooth wall tubing.
Deliver warm inspired gas from the moment of intubation.
For use in patients1kg-80kg (2-175lb). For <2kg (5lb), use with Darvall’s new low-flow heated Lack circuit.
- 2kg to 80kg (5-175lb) use with Darvall’s Stingray absorber.
- 5-2kg (1-5lb) early spey/neuters use with Darvall’s new low-flow Lack circuit.
- <0.5kg (1lb) use with Darvall’s Heated ZDS Qube.
Darvall’s Heated Breathing System provides immediate warm air to the anaesthetised patient from the first breath from intubation.
Darvall’s Heated Smooth-Wall Circuits can be used with all manufacturer’s circle systems down to 5kg (11lb).

Reduce critical heat loss from the first breath with the Darvall Heated Breathing Circuits starter kit. (Part 9855).

Part	Patient	Weight	Circuit Tube ID	Cuff Collar	Tube Length	Volume
8347	Cat/Small Dog	2-30kg (4-65lb)	12mm (1/2”)	Creme	1.6M (5’)	180 ml
8348	Medium/Large Dog	30-80kg (65-175lb)	16mm (5/8”)	Blue	1.6M (5’)	270 ml

The Darvall Heated Lack non-rebreathing circuit

Prevent hypothermia in your tiniest patients including early spey/neuters 0.5-2kg (1-5lb). The Darvall Lack circuit is the only non-rebreathing system that can be effectively warmed using heated smooth-wall circuits.

Key Features of Cozy Heated Lack circuit.

Use with Cozy Heated Smooth Wall circuits.
Low volume, low resistance smooth-wall tubing.
Fail-safe Adjustable Pressure-Limiting (APL) Valve.
Use efficient low gas flows on very small patients below 10kg (20lb).
Incorporating Darvall’s unique Minimum Dead Space (MDS) Y-piece.

Lack Adapter Kit (PN 10240) is included in the Darvall Heated Breathing Circuits starter kit. Also available as a non-heated Lack non-rebreathing circuit with 12mm non-heated smooth-wall tubes. (Part 8305).

Darvall Cozy Heated Qube

Darvall’s Heated ZDS Qube with thermostatic control, heating to 42°C (108^oF) delivering 38^oC (100^oF) inspired gas is a totally new solution to managing hypothermia in tiny patients.

Zero Dead Space or face mask Qube and circuit has unidirectional flow.
Use for exotics, rodents, birds, and neonatal pups and kittens.
Non-rebreathing Circuit – O₂ 200ml/kg/min.
Supplied with 20mm and 10mm diameter diaphragms.
Supplied with 3 interchangeable masks with diaphragms as shown.
ZDS facemask supplied with all Stinger machine models, includes 20mm & 10mm OD orifice diaphragm.
Heated Qube prevents heat loss from induction.

Deliver warm air and manage hypothermia in your smallest patients from the first breath with Cozy Exotics Heated Anaesthesia Starter Kit (PN 10236).

Part #	ZDS Qube Masks – Autoclavable	Specifications
8416	Mask 20mm (3/4”) orifice offset tapered Use: very small exotics e.g. mice	Diaphragm TPE 20mm (3/4″) OD 8mm (0.3″) ID
8415	Mask 20mm (3/4”) orifice straight Use: small exotics, birds, rodents & reptiles	Diaphragm TPE 20mm (3/4″) OD 8mm (0.3″) ID
8414	Mask 25mm (1”) orifice tapered Use: medium exotics, birds, rodents & reptiles	Diaphragm TPE 25mm (1″) OD 12mm (0.5″) ID
8413	Mask 40mm (1.5″) orifice offset tapered Use: medium exotics, birds, rodents & reptiles	Diaphragm Silicon 40mm (1.5″) OD 20mm (3/4″) ID
8420	Endotracheal Tube Adaptor 15mm ID opening Use: Intubated exotics, birds, rodents, reptiles, small rabbits, pups, kittens	Use with standard ET tube 15mm OD adapters (15mm (0.6″) ID) Use: Intubated animals, birds, reptiles
10028	ADDITIONAL ITEM: ZDS Qube Mask Extension	Use: Extends mask 100mm (4”) from Qube Use with all ZDS Masks above

our clients

"At the University Veterinary Teaching Hospital Sydney we use Darvall Warm Air Heating equipment on almost all of our anaesthetised patients and many of our critical care patients."

Louise McGregor - The University of Sydney Veterinary Teaching Hospital, Sydney, Australia.

“Our patients are coming out of anaesthesia 3.1oC higher now we are using Darvall’s Heated Anaesthesia Circuits. We got one for a 2-week trial and then bought 3 units.”

Southern Counties Veterinary Hospital UK

“Your heated breathing circuits are top notch”

Vicki Lipsey, Judson Road Animal Clinic, Longview, TX

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Bowling, PA et al (2021) Effects of a Heated Anesthesia Breathing Circuit on Body Temperature in Anesthetized Rhesus Macaques (Macaca mulatta) Journal of the American Association for Laboratory Animal Science. 2021; p1.

Brodbelt DC et al. (2008) Study of 98,036 dogs and 79,178 cats in 117 UK veterinary practices during a 2-year study period. Veterinary Anaesthesia and Analgesia; 35: 365-373.